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Abstract
As the number of products being sold online increases, it is becoming increasingly difficult for customers to make purchasing decisions based on only pictures and short product descriptions. Thus, customer reviews, particularly the text describing the features, comparisons and experiences of using a particular product provide a rich source of information to compare products and make purchasing decisions. Especially, all kinds of reviews from various people have different degree of impact on a buyer, that is, we tend to believe our friends who always make right decisions than others. In this paper, we present an individual feature-based product ranking technique that mines thousands of customer reviews. By grouping users into unfamiliar users and familiar users according to the fact whether the client has almost always right ideas as far as one has concerned we attach different weights to them based on the friend ranking list. Friends on the top of the list are expected to be more reliable than the rest. After founding the client's friend set{F_j, S_k}, we extract crucial information from users' reviews. By realizing key words in a sentence, we classify comments into 4 representative sentences-Active Direct sentence(AD), Inactive Direct sentence(ID), Active Indirect sentence(AI), and Inactive Indirect sentence(II). Afterwards, we construct a weighted graph considering the product weight itself and the edge between every 2 relevant products, using ratios AD/ID and ID/II. The last step is that the client ranks search result with the average reliabilities of himself with respect to reviews of specific feature. Through calculation, we have a weighted score list, helping the client make purchase intentions.
Customer reviews play a major role in online shopping, but there is hardly any support for aggregating the opinions of multiple reviewers, especially when the user is interested in certain aspects only. Current retrieval methods cannot handle the issues of limited credibility, contradictions and information omission when dealing with this type of documents. For addressing these problems, we investigate two multi-valued logic retrieval models. Subjective logic was specifically developed for considering uncertainty and subjective opinions. As an alternative, we regard a probabilistic version of a 4-valued logic addressing missing and inconsistent information. For an aspect-product pair, we get a probability distribution over the truth values and use them for ranking the search results. Our experimental results on a data set from the hotel domain show that our proposed approaches outperform the traditional keyword-based methods for the task of ranking items based on reviews. Moreover, the logic-based methods are more transparent than other approaches.
Over the past few years, more and more consumers have come to read online reviews when they shop online. To support consumers' purchase decisions, many scholars focus on ranking products based on online reviews and propose various methods and techniques. Generally, the process of information fusion for ranking products based on online reviews consists of three stages: product feature extraction, sentiment analysis, and ranking products. In this paper, we review the existing studies on processes and methods of information fusion for each stage. Furthermore, we briefly review the existing research on information fusion based on online reviews in other fields. Finally, we summarize the main conclusions of this paper and point out the future research direction.
Online customer reviews (OCRs) provide much information about products or service, but the mass of information increases the difficulty for customers to make decisions. Thus, we establish a multi-criteria decision making (MCDM) model to evaluate products or service. To analyze OCRs, the sentiment analysis (SA) is introduced to identify the sentiment orientation of reviews. Considering that the textual information in OCRs is linguistic information, probabilistic linguistic term sets (PLTSs) are applied to present the results of the SA. A process of extracting probabilistic linguistic information based on SA from OCRs is also presented. Then, for the MCDM problems with unknown criteria weights, we combine the PP (projection pursuit) method and the MULTIMOORA (multiplicative multi-objective optimization by ratio analysis) method, and develop an extended method (named as the PP-MULTIMOORA method). The projection pursuit (PP) method is developed to derive objective criteria weights and the MULTIMOORA method is to derive final rankings of products or service. Finally, we apply the proposed model to a case of evaluating doctors’ service quality and further conduct a comparative analysis to illustrate the effectiveness of our work.
The huge amount of information that is available in social media today has resulted in a pressing demand for information retrieval models to support users in different retrieval tasks in this area. Evaluation of products or services based on other consumers’ reviews are examples of retrieval tasks where users benefit from the information in social media. However, as information in online reviews is provided from different customers, the reviews differ in their degree of credibility. Furthermore, not every detail of a product is reviewed but needs to be taken care when validating a product. Finally, reviews contain contradictions. In this work, we propose a logic-based pipeline to develop a social media retrieval model in which issues of credibility, omissions and contradictions are considered. For modeling these criteria, our approach depends on a probabilistic four-valued logic combined with an open world assumption which employs the unknown knowledge in retrieval tasks.
Amaç: Yoğun tempolu çalışma koşulları, stres, şehir hayatının trafik, gürültü, hava kirliliği gibi olumsuz etkenleri nedeniyle tatil, insan hayatının vazgeçilmez bir parçası haline gelmiştir. İnsanlar yılda en az bir defa turistik faaliyetlere katılım için bir satın alma kararı vermek durumunda kalmaktadır. Tüketim ve tüketme düşüncesinin hakim olduğu bir dünyada tüketicileri anlama, tüketicileri anlamak için de satın almayla ilgili her şeyin öğrenilmesi gerekmektedir. İnternet ise artık insan hayatının anahtar bileşenlerinden biri olarak değerlendirilmektedir. Hal böyle olunca tüketici ve internet kavramları incelenmesi gereken temel konular olarak gündeme gelmektedir. Çalışmada otel müşterilerinin satın alma karar sürecinde internet kullanım alışkanlıklarına ilişkin bir durum analizi yapılması amaçlanmıştır. Yöntem: Veri toplama aracı olarak anket tercih edilmiş, 3 yıldız ve üzeri otel işletmelerinde konaklayan müşterilere uygulanmıştır. 682 anket değerlendirmeye alınmış, veriler SPSS aracılığıyla analiz edilmiştir.Bulgular: Katılımcıların %79.2’u için internet günlük hayatlarında zamanlarının büyük bir kısmını alan önemli bir bileşendir. Katılımcıların %40.6’sı otel tercihi için internette 1-2 saat arası zaman harcadığını belirtmektedir. Otel tercihi için internette geçirilen sürenin cinsiyetler açısından farklılık gösterdiği saptanmıştır. Erkeklerin daha çabuk karar verdikleri, kadın katılımcıların %37.4’ünün ise 3 saatten fazla internette kalarak otel tercihlerini şekillendirdikleri tespit edilmiştir. Sonuç: Teknoloji gelişimiyle beraber birçok satın alma kararında olduğu gibi konaklama işletmesi tercihlerinde de insanları internet üzerinde yoğun zaman harcamaya yöneldikleri dikkat çekmektedir. Cinsiyet bağlamında ise kadınların bu araştırmalara erkeklere oranla daha fazla zaman ayırdıkları saptanmıştır. Bunun temel nedenleri arasında kadınların daha detaycı olmaları ve birçok beklentinin bir arada karşılanması arzularının yüksekliği gösterilebilir. Ayrıca gerçekleştirilecek konaklama maliyetlerinin erkekler tarafından karşılanma olasılığının yüksek olmasının kadın katılımcıların bu konudaki hassasiyetlerini arttırmış olabileceği de unutulmamalıdır.
Purpose
Online product ratings play an important role in the decision-making process of consumers, which are not only sources of information used by consumers to understand the function and quality of a product or service but also sources of information used to find desirable products. The purpose of this paper is to develop a decision-based method for supporting the purchase decisions of consumers based on not only the online product ratings but also the actual product attributes.
Design/methodology/approach
First, two types of utility values are designed to measure the preference of the consumer based on either online ratings or actual product attributes. Then, the traditional TOPSIS method is adopted to achieve a comprehensive value by integrating the two types of utility values so that all of the alternative products can be ranked. Further, a product selection support system prototype is designed and developed to support the purchase decisions of consumers.
Findings
To help consumers select desirable products efficiently, it is necessary to develop a product selection method based on the online ratings of alternative products and consumer expectations.
Practical implications
The research shows that the proposed method can not only support consumers’ purchase decisions based on a large number of online product ratings but also help manufacturers to find out consumers’ demands or requirements on products so as to facilitate the design of new products or the improvement of products. On the basis of the proposed method, the developed system prototype is helpful for consumers to select desirable products.
Originality/value
To support the purchase decisions of consumers, a new decision-based method for selecting desirable online products is proposed.
The online review plays an important role as electronic word-of-mouth (eWOM) for potential consumers to make informed purchase decisions. However, the large number of reviews poses a considerable challenge because it is impossible for customers to read all of them for reference. Moreover, there are different types of online reviews with distinct features, such as numeric ratings, text descriptions, and comparative words, for example; such heterogeneous information leads to more complexity for customers. In this paper, we propose a method to integrate such rich and heterogeneous information. The integrated information can be classified into two categories: descriptive information and comparative information. The descriptive information consists of online opinions directly given by consumers using text sentiments and numeric ratings to describe one specific product. The comparative information comes from comparative sentences that are implicitly embedded in the reviews and online comparative votes that are explicitly provided by third-party websites to compare more than one product. Both descriptive information and comparative information are integrated into a digraph structure, from which an overall eWOM score for each product and a ranking of all products can be derived. We collect both descriptive and comparative information for three different categories of products (mobile phones, laptops, and digital cameras) during a period of 10 days. The results demonstrate that our method can provide improved performance compared with those of existing product ranking methods. A ranking system based on our method is also provided that can help consumers to compare multiple products and make appropriate purchase decisions effortlessly.
The US Environmental Protection Agency has used adenovirus, a microorganism on the Drinking Water Contaminant Candidate List, in setting ultraviolet (UV) dosage requirements under the Long Term 2 Enhanced Surface Water Treatment Rule. As a result, the UV dose required for 4-log virus removal has been increased from 40 to ∼200 mJ/cm2. Adenovirus is more resistant to UV than any other waterborne pathogen studied. Although setting the required dose on the basis of this microorganism is clearly protective of public health, concerns exist that it may be overly protective because there is little or no information on the occurrence of adenovirus in groundwater and its transmission through water. Furthermore, no standard method is available for its detection. This report summarizes the state of adenovirus science and proposes recommendations to ensure that regulatory decisions can be based on a sufficient body of scientific information.
Bench-scale experiments determined the germicidal effects of varying dosages of polychromatic ultraviolet (UV) radiation on oocysts of Cryptosporidium parvum. C. parvum oocysts suspended in treated surface water were irradiated with polychromatic light emitted by either a medium-pressure, continuous-wave UV lamp or a pulsed-UV lamp then assayed with human cell culture techniques. Experiments conducted using pulsed-UV doses of ≥ 16 mJ/cm 2 provided > 2-log inactivation of suspended oocysts of C. parvum. Experiments at lower UV dosages established a dose-response relationship with both the medium-pressure and pulsed-UV lamps. When disinfection results from both light sources were compared on an equivalent dosage basis, no statistical difference in disinfection power was found between the medium-pressure and pulsed-UV lamps. Results from both lamps showed that UV doses as low as 7.5 and 11 mJ/cm 2 provided inactivation of infectious oocysts of C. parvum at rates of 1 log (90%) and 2 log (99%), respectively. The authors also examined UV disinfection of heterotrophic bacteria and Escherichia coli. They found the response of heterotrophic bacteria to be statistically different from that of C. parvum, whereas E. coli's response to UV light did not statistically differ from that of C. parvum. This suggests that E. coli may be a surrogate organism for C. parvum disinfection provided by UV technologies.
A pilot-scale study investigating the use of low-pressure, high-intensity UV radiation for disinfection of urban wastewater was conducted. The inactivation of coliform bacteria, wastewater-indigenous enteric viruses, seeded poliovirus, and seeded F-specific coliphage was studied. During the course of the pilot study, infectious human adenoviruses were isolated from 15 of 16 large-volume samples of UV-disinfected secondary- and tertiary-treated wastewater. Half of the tertiary-treated, UV-disinfected effluent samples from which the adenoviruses were isolated had total coliform concentrations that complied with California's Water Recycling Criteria. To determine the relative UV resistance of the adenovirus isolates, purified viruses were seeded into tertiary-treated wastewater and exposed to low-pressure, high-intensity, collimated UV radiation. A dose of approximately 170 mW-s/cm2 was required to achieve 99.99% inactivation. These findings suggest that UV doses effective at meeting certain wastewater regulations for total coliform bacteria may not provide suitable inactivation of the UV-resistant human adenoviruses.
Textual information in the world can be broadly categorized into two main types: facts and opinions. Facts are objective expressions about entities, events and their properties. Opinions are usually subjective expressions that describe people's sentiments, appraisals or feelings toward entities, events and their properties. The concept of opinion is very broad. In this chapter, we only focus on opinion expressions that convey people's positive or negative sentiments. Much of the existing research on textual information processing has been focused on mining and retrieval of factual information, e.g., information retrieval, Web search, text classification, text clustering and many other text mining and natural language processing tasks. Little work had been done on the processing of opinions until only recently. Yet, opinions are so important that whenever we need to make a decision we want to hear others' opinions. This is not only true for individuals but also true for organizations. One of the main reasons for the lack of study on opinions is the fact that there was little opinionated text available before the World Wide Web. Before the Web, when an individual needed to make a decision, he/she typically asked for opinions from friends and families. When an organization wanted to find the opinions or sentiments of the general public about its products and services, it conducted opinion polls, surveys, and focus groups. However, with the Web, especially with the explosive growth of the user-generated content on the Web in the past few years, the world has been transformed. The Web has dramatically changed the way that people express their views and opinions. They can now post reviews of products at merchant sites and express their views on almost anything in Internet forums, discussion groups, and blogs, which are collectively called the user-generated content. This online word-of-mouth behavior represents new and measurable sources of information with many practical applications. Now if one wants to buy a product, he/she is no longer limited to asking his/her friends and families because there are many product reviews on the Web which give opinions of existing users of the product. For a company, it may no longer be necessary to conduct surveys, organize focus groups or employ external consultants in order to find consumer opinions about its products and those of its competitors because the user-generated content on the Web can already give them such information.
The Web has become an excellent source for gathering consumer opinions.
There are now numerous Web sites containing such opinions, e.g.,
customer reviews of products, forums, discussion groups, and blogs.
This paper focuses on online customer reviews of products. It makes
two contributions. First, it proposes a novel framework for analyzing
and comparing consumer opinions of competing products. A prototype
system called Opinion Observer is also implemented. The system is
such that with a single glance of its visualization, the user is
able to clearly see the strengths and weaknesses of each product
in the minds of consumers in terms of various product features. This
comparison is useful to both potential customers and product manufacturers.
For a potential customer, he/she can see a visual side-by-side and
feature-by-feature comparison of consumer opinions on these products,
which helps him/her to decide which product to buy. For a product
manufacturer, the comparison enables it to easily gather marketing
intelligence and product benchmarking information. Second, a new
technique based on language pattern mining is proposed to extract
product features from Pros and Cons in a particular type of reviews.
Such features form the basis for the above comparison. Experimental
results show that the technique is highly effective and outperform
existing methods significantly.
It is a common practice that merchants selling products on the Web
ask their customers to review the products and associated services.
As e-commerce is becoming more and more popular, the number of customer
reviews that a product receives grows rapidly. For a popular product,
the number of reviews can be in hundreds. This makes it difficult
for a potential customer to read them in order to make a decision
on whether to buy the product. In this project, we aim to summarize
all the customer reviews of a product. This summarization task is
different from traditional text summarization because we are only
interested in the specific features of the product that customers
have opinions on and also whether the opinions are positive or negative.
We do not summarize the reviews by selecting or rewriting a subset
of the original sentences from the reviews to capture their main
points as in the classic text summarization. In this paper, we only
focus on mining opinion/product features that the reviewers have
commented on. A number of techniques are presented to mine such features.
Our experimental results show that these techniques are highly effective.
Adenoviruses are resistant to monochromatic, low-pressure (LP) UV disinfection—but have been shown to be susceptible to inactivation
by polychromatic, medium-pressure (MP) UV—when assayed using cell culture infectivity. One possible explanation for the difference
between UV lamp types is that the additional UV wavelengths emitted by MP UV enable it to cause greater damage to viral proteins
than LP UV. The objective of this study was to examine protein damage in adenoviruses treated with LP and MP UV. Results show
that MP UV is more effective at damaging viral proteins at high UV doses, though LP UV caused some damage as well. To our
knowledge, this study is the first to investigate protein damage in UV-treated adenovirus, and the overview presented here
is expected to provide a basis for further, more detailed work.
UV disinfection is highly effective against most pathogens, with the exception of the adenoviruses (AD). To date, many studies
have focused on low-pressure (LP) UV inactivation of AD, but little is known about the effect of medium-pressure (MP) UV inactivation
of AD. Despite numerous studies of LP UV inactivation of AD, extreme variabilities in the LP UV dose requirements of AD had
been observed because of differing experimental conditions used, such as the types of cell lines used for AD enumeration.
This study therefore investigates the effect of three different host cell lines (PLC/PRF/5, human embryonic kidney 293 [HEK293],
and XP17BE) on the LP and MP UV dose requirements of AD serotype 5 (AD5), AD40, and AD41 under similar experimental settings.
Results showed that for 4-log inactivation of AD, LP UV and MP UV doses needed to be in the ranges of 123 to 182 mJ/cm2 and 65 to 90 mJ/cm2, respectively, when HEK293 and PLC/PRF/5 cells were used for enumeration. The UV doses required for MP UV inactivation of
AD were significantly lower than those required for LP UV inactivation (P value < 0.05). When different cell lines were used for enumeration, UV dose requirements for AD differed. AD were portrayed
to be most susceptible to UV (LP UV doses of <57 mJ/cm2 and MP UV doses of <42 mJ/cm2 for 4-log AD inactivation) when the XP17BE cells were used as the host cell. The use of different cell lines for AD enumeration
affected LP UV dose results more significantly than MP UV dose results (P value < 0.05). Cell line variability factors for LP UV disinfection (CLLP) and MP UV disinfection (CLMP) for AD5, AD40, and AD41 enumerated with HEK293, PLC/PRF/5, and XP17BE cells were in the ranges of 1.0 to 3.2 and 1.0 to
2.5, respectively.
Adenovirus is a focus of the water treatment community because of its resistance to standard, monochromatic low-pressure (LP) UV irradiation. Recent research has shown that polychromatic, medium-pressure (MP) UV sources are more effective than LP UV for disinfection of adenovirus when viral inactivation is measured using cell culture infectivity assays; however, UV-induced DNA damage may be repaired during cell culture infectivity assays, and this confounds interpretation of these results. Objectives of this work were to study adenoviral response to both LP and MP UV using (i) standard cell culture infectivity assays and (ii) a PCR assay to directly assess damage to the adenoviral genome without introducing the virus into cell culture. LP and MP UV dose response curves were determined for (i) log inactivation of the virus in cell culture and (ii) UV-induced lesions per kilobase of viral DNA as measured by the PCR assay. Results show that LP and MP UV are equally effective at damaging the genome; MP UV is more effective at inactivating adenovirus in cell culture. This work suggests that the higher disinfection efficacy of MP UV cannot be attributed to a difference in DNA damage induction. These results enhance our understanding of the fundamental mechanisms of UV disinfection of viruses-especially double-stranded DNA viruses that infect humans--and improve the ability of the water treatment community to protect public health.
Survival was measured as a function of the dose of germicidal UV light for the bacteria Escherichia coli, Salmonella typhi, Shigella sonnei, Streptococcus faecalis, Staphylococcus aureus, and Bacillus subtilis spores, the enteric viruses poliovirus type 1 and simian rotavirus SA11, the cysts of the protozoan Acanthamoeba castellanii, as well as for total coliforms and standard plate count microorganisms from secondary effluent. The doses of UV light necessary for a 99.9% inactivation of the cultured vegetative bacteria, total coliforms, and standard plate count microorganisms were comparable. However, the viruses, the bacterial spores, and the amoebic cysts required about 3 to 4 times, 9 times, and 15 times, respectively, the dose required for E. coli. These ratios covered a narrower relative dose range than that previously reported for chlorine disinfection of E. coli, viruses, spores, and cysts.
Adenovirus vaccines have greatly reduced military respiratory disease morbidity since the 1970s. However, in 1995, for economic
reasons, the sole manufacturer of these vaccines ceased production. A population-based adenovirus surveillance was established
among trainees with acute respiratory illness at 4 US military training centers as the last stores of vaccines were depleted.
From October 1996 to June 1998, 1814 (53.1%) of 3413 throat cultures for symptomatic trainees (78% men) yielded adenovirus.
Adenovirus types 4, 7, 3, and 21 accounted for 57%, 25%, 9%, and 7% of the isolates, respectively. Unvaccinated trainees were
much more likely than vaccinated trainees to be positive for types 4 or 7 (odds ratio [OR] = 28.1; 95% CI, 20.2–39.2). Two
training centers experienced epidemics of respiratory disease affecting thousands of trainees when vaccines were not available.
Until a new manufacturer is identified, the loss of orphaned adenovirus vaccines will result in thousands of additional preventable
adenovirus infections.
A novel nucleic acid stain, SYBR Gold, was used to stain marine viral particles in various types of samples. Viral particles stained with SYBR Gold yielded bright and stable fluorescent signals that could be detected by a cooled charge-coupled device camera or by flow cytometry. The fluorescent signal strength of SYBR Gold-stained viruses was about twice that of SYBR Green I-stained viruses. Digital images of SYBR Gold-stained viral particles were processed to enumerate the concentration of viral particles by using digital image analysis software. Estimates of viral concentration based on digitized images were 1.3 times higher than those based on direct counting by epifluorescence microscopy. Direct epifluorescence counts of SYBR Gold-stained viral particles were in turn about 1.34 times higher than those estimated by the transmission electron microscope method. Bacteriophage lysates stained with SYBR Gold formed a distinct population in flow cytometric signatures. Flow cytometric analysis revealed at least four viral subpopulations for a Lake Erie sample and two subpopulations for a Georgia coastal sample. Flow cytometry-based viral counts for various types of samples averaged 1.1 times higher than direct epifluorescence microscopic counts. The potential application of digital image analysis and flow cytometry for rapid and accurate measurement of viral abundance in aquatic environments is discussed.
Adenoviral evolution has generated strategies to resist host cell antiviral systems, but molecular mechanisms for evasion of interferon (IFN) effects by adenoviruses during late-phase infection are poorly defined. In this study, we examined adenovirus type 5 (AdV) effects on IFN-gamma-dependent gene expression and Janus family kinase-signal transducer and activator of transcription signaling components in human tracheobronchial epithelial cells. We found that AdV infection specifically inhibited IFN-gamma-dependent gene expression in airway epithelial cells without evidence of epithelial cell injury or generation of a soluble extracellular inhibitor. Furthermore, infection with AdV for 18-24 h blocked phosphorylation/activation of the Stat1 transcription factor that regulates IFN-gamma-dependent genes. Although AdV also inhibited IFN-alpha-dependent phosphorylation of Stat1 and Stat2, interleukin-4-dependent phosphorylation of the related transcription factor Stat6 was not affected, indicating that the virus selectively affected specific signaling pathways. Our results indicate that AdV inhibition of the IFN-gamma signal transduction cascade occurs through loss of ligand-induced receptor complex assembly and consequent component phosphorylation and suggest that lack of complex assembly is due to decreased expression of the IFN-gammaR2 chain of the IFN-gamma receptor. IFN-gammaR2 is required at an early step in Janus family kinase-signal transducer and activator of transcription pathway activation and is expressed at low levels in airway epithelial cells, supporting the concept that adenoviral down-regulation of the level of this IFN-gamma receptor component allows for persistent modulation of IFN-gamma-dependent gene expression.
Previous work has shown that the avian reovirus cell-attachment sigma C (sigmaC) protein is a multimer. In the first part of this study the oligomerization state of intracellularly synthesized sigmaC was analysed by different approaches, including SDS-PAGE, chemical cross-linking, sedimentation and gel filtration analysis. All these approaches indicated that protein sigmaC in its native state is a homotrimer. In the second part of the present work we investigated the effect of different factors and reagents on oligomer stability, in order to elucidate the nature of the forces that maintain the conformational stability of the homotrimer. Our results, based on the stabilizing effect conferred by reducing agents, demonstrate that the sigmaC subunits are not covalently bound via disulfide linkages. They further suggest that the formation of an intrachain disulfide bond between the two cysteine residues of the sigmaC polypeptide has a negative effect on oligomer stability. The susceptibility of the trimer to pH, temperature, ionic strength, chemical denaturants and detergents indicates that hydrophobic interactions contribute much more to oligomer stability than do ionic interactions and hydrogen bonding. Finally, our results also reveal that mammalian and avian reovirus cell attachment proteins follow different subunit dissociation pathways.
After 25 years of successful control through immunization, respiratory infections due to adenoviruses have reemerged to threaten
the health of young adults in the military. Shortly after the loss of adenovirus vaccine supplies, a large outbreak of respiratory
illness was observed at the United States Navy's sole basic training center. Laboratory testing confirmed 541 cases of adenovirus
infection, including 378 cases due to serotype 7 and 132 cases due to serotype 3. This outbreak was remarkable because of
its unique serotype distribution and the large amount of data available to describe demographic factors associated with infection.
This was the largest outbreak of respiratory illness due to adenovirus types 7 and 3 documented in recent history, and it
portends even greater challenges for young adults in the military in the postvaccine era.
The increased use of UV radiation as a drinking water treatment technology has instigated studies of the repair potential
of microorganisms following treatment. This study challenged the repair potential of an optimally grown nonpathogenic laboratory
strain of Escherichia coli after UV radiation from low- and medium-pressure lamps. Samples were irradiated with doses of 5, 8, and 10 mJ/cm2 from a low-pressure lamp and 3, 5, 8, and 10 mJ/cm2 from a medium-pressure UV lamp housed in a bench-scale collimated beam apparatus. Following irradiation, samples were incubated
at 37°C under photoreactivating light or in the dark. Sample aliquots were analyzed for up to 4 h following incubation using
a standard plate count. Results of this study showed that E. coli underwent photorepair following exposure to the low-pressure UV source, but no repair was detectable following exposure to
the medium-pressure UV source at the initial doses examined. Minimal repair was eventually observed upon medium-pressure UV
lamp exposure when doses were lowered to 3 mJ/cm2. This study clearly indicates differences in repair potential under laboratory conditions between irradiation from low-pressure
and medium-pressure UV sources of the type used in water treatment.
Increasingly large numbers of customers are choosing online shopping because of its convenience, reliability, and cost. As the number of products being sold online increases, it is becoming increasingly difficult for customers to make purchasing decisions based on only pictures and short product descriptions. On the other hand, customer reviews, particularly the text describing the features, comparisons and experiences of using a particular product provide a rich source of information to compare products and make purchasing decisions. Online retailers like Amazon.com1 allow customers to add reviews of products they have purchased. These reviews have become a diverse and reliable source to aid other customers. Traditionally, many customers have used expert rankings which rate limited a number of products. Existing automated ranking mechanisms typically rank products based on their overall quality. However, a product usually has multiple product features, each of which plays a different role. Different customers may be interested in different features of a product, and their preferences may vary accordingly. In this paper, we present a feature-based product ranking technique that mines thousands of customer reviews. We first identify product features within a product category and analyze their frequencies and relative usage. For each feature, we identify subjective and comparative sentences in reviews. We then assign sentiment orientations to these sentences. By using the information obtained from customer reviews, we model the relationships among products by constructing a weighted and directed graph. We then mine this graph to determine the relative quality of products. Experiments on Digital Camera and Television reviews from real-world data on Amazon.com are presented to demonstrate the results of the proposed techniques.
This article shows that multiple disinfectants can effectively protect public health and meet emerging US Environmental Protection Agency requirements. The authors demonstrate that adenovirus inactivation can be effectively achieved with the combination of ultraviolet (UV), free chlorine (Cl 2), and conversion to chloramines. Sequential addition of Cl 2 and conversion to chloramines are far more effective than the use of preformed chloramines at achieving adenovirus inactivation. This research was undertaken to show that UV disinfection at typical doses of 40 mJ/cm 2 followed by the sequential addition of chlorine to water containing ammonia ultimately resulting in chloramines could effectively achieve a 4-log adenovirus inactivation. This method will enable water utilities that have difficulty maintaining a free Cl 2 residual to meet the new Long Term 2 Enhanced Surface Water Treatment Rule requirements using UV-Cl 2 chloramines. - LH.
Recent studies have shown that Cryptosporidium parvum oocysts demonstrate high susceptibility to low dosages of medium-pressure ultraviolet (UV) light. These investigations have raised several questions, which include determination of minimum medium-pressure UV dosages necessary to inactivate C. parvum oocysts, elucidation of differences (if any) between medium-and low-pressure UV light for inactivating C parvum oocysts, and evaluation of medium-pressure UV effectiveness in inactivating oocysts suspended in poorer quality water. To compare low- and medium-pressure UV, the authors exposed oocysts suspended in deionized water to UV delivered by either medium- or low-pressure UV lamps at bench scale using a collimated beam apparatus. The applied UV dosages ranged from 3 to 33 mJ/cm², and oocyst inactivation was assessed using the neonatal mouse infectivity assay. At 3 mJ/cm², medium-pressure UV showed a 3.4-log inactivation of oocysts, and low-pressure UV showed a 3.0-log inactivation, demonstrating medium- and low-pressure UV did not differ significantly in inactivating C. parvum oocysts.
It seems to be almost something like a natural law, that all technical equipment used by human beings inevitably generates noise. On the traffic side we can observe that besides air pollution by vehicles the continuously growing traffic noise has become a severe problem. More and more citizens feel affected. Within the framework of the research programme "Mobility and Traffic" the German Federal Ministry of Education and Research supports a lot of work in the field of noise reduction. The activities are focussed on noise abatement at the source. They are set up in a network of cross-sectional research called "Quiet Traffic", which covers common methods and procedures, noise effects on humans, road and rail traffic noise as well as air traffic noise (takeoff and landing procedures). On a bilateral basis of cooperation with France (DEUFRAKO) we try to set a new focus on quiet traffic, which should create some added value of the research on both sides. At the European level, the CALM-Network, which is funded by the DG Research of the European Commission, has issued the strategy paper "Research for a Quieter Europe" in July 2002. This paper is intended as a contribution to the Sixth Framework. Programme for European Research launched late last year. So there are some good points from which to continue or to start with joint efforts, which are urgently needed to fight traffic noise in Europe.
u.v. dose/survival response curves were developed for E. coli, S. faecalis, poliovirus and reovirus. The influence of photoreactivation on the bacterial curves was examined. A maximum photoreactivation of 3.4 and 2.4 log of u.v. inactivated E. coli and S. faecalis populations, respectively, was observed. When allowing for photoreactivation, the dose required for 99.9% inactivation of the bacteria was approximately twice that required when photoreactivation was not considered. Reovirus, a double-standard RNA virus, was found to be significantly more resistant to u.v. radiation than poliovirus, a single-stranded RNA virus. The viruses in general, were found to be more resistant to u.v. radiation than the bacteria.
Ultraviolet light is an attractive alternative to chemical disinfection of water, but little is known about its ability to inactivate important waterborne pathogens such as hepatitis A virus. Therefore, the sensitivity of HAV strain HM-175, coxsackievirus type B-5, rotavirus strain SA-11, and bacteriophages MS2 and phiX174 to ultraviolet radiation of 254 nm wavelength in phosphate buffered water was determined. Purified stocks of the viruses were combined and exposed to collimated UV radiation in a stirred reactor for a total dose of up to 40 mW sec/cm 2 . Virus survival kinetics were determined from samples removed at dose intervals. The 4 log10 (99.99%) inactivation doses for HAV, CB5, SA-11 and phiX174 were 16, 29, 42 and 9 mW sec/cm2, respectively. MS2 exhibited the greatest resistance in buffered water with less than a 1 log10 reduction observed after exposure to 25 mW sec/CM2. A 15 mW sec/cm2 exposure induced a 7 log10 reduction of phiX174, while inactivation of HAV, CB5 and SA11 was intermediate, with at least 3 log10 reductions occurring after a 20 mW sec/cm2 exposure. The results of these experiments indicate that UV radiation can effectively inactivate viruses of public health concern in drinking water.
The enteric adenoviruses of subgroup F (Ad40 and Ad41) pose some special problems of cultivation, as they cannot be readily
passaged in many of the cell types used to propagate the more commonly used subgroup C serotypes (Ad2 and Ad5), and there
is no standard plaque assay: A full discussion of the observations from many laboratories is included in a recent review (1). For the purposes of this chapter, I will describe the methods developed in my laboratory to passage Ad40 in 293 and KB16
cells, to assay the virus by a variety of methods, to purify the virus by cesium chloride density gradient centrifugation,
and to obtain viral DNA. Most of the methods have been derived from those developed for Ad5, but with constraints imposed
by the more fastidious nature of the enteric adenoviruses.
Adenoviruses have been detected in raw sewage throughout the world and are associated with a number ofhuman illnesses but their occurrence and pathogenicity have not been well studied. A risk assessment approach was used to determine their significance as a waterborne pathogen. There arc 47 types of adenoviruses and the diseases resulting from infections include conjunctivitis, pharyngitis, pneumonia, acute and chronic appendicitis, cxanthematous disease, bronchiolitis, acute respiratory disease, and gastroenteritis (types 40 and 41). Adenovirus is considered to be only second to rolavirus in terms of its significance as a pathogen of childhood gastroenteritis. Adenovirus infections are usually acute and self-limiting with a greater severity of illness occurring in the immunocompromised (e.g. AIDS patients and transplant recipients). They are repofled to be more resistant to inactivation by UV than enteroviruses and are sometimes detected at higher levels in polluted waters. There are documented outbreaks of conjunctivitis due to adenovirus types 3 & 4 associated with swimming in contaminated recreational waters. Based on the data obtained from human dose-response studies, the exponential model [Pi = l -exp(-rN); r = 0.4172] was chosen for this risk assessment. Annual risks of infection in drinking water for adenovirus at average levels of 1/1,000L to 1/100L ranged from 8.3/10,000 to 8.3/1,000, respectively. Using monitoring data from a recreational water, risks were calculated to be as high as 1/1,000 for a single exposure.
Adenoviruses encode proteins that block responses to interferons, intrinsic cellular apoptosis, killing by CD8+ cytotoxic T lymphocytes and killing by the death ligands TNF, Fas ligand and TRAIL. The viral proteins are believed to prolong acute and persistent adenovirus infections. The proteins may prove useful in protecting adenovirus gene therapy vectors and transplanted cells from the immune system.
Nucleic acid (NA) amplification techniques are useful to detect viruses in water and other environmental samples because they are highly sensitive, specific and can detect fastidious enteric viruses that do not grow well or not at all in cell cultures. However, RT-PCR was found to detect inactivated viruses. In terms of risks to public health this constitutes a false positive result, as inactivated viruses are no longer infectious. When poliovirus type 1 and coliphage MS2 were studied for (a) persistence in water and sewage and (b) inactivation in water by free chlorine, chlorine dioxide and UV radiation, RT-PCR assays underestimated virus inactivation. The use of multiple RT-PCR amplification sites, larger RT-PCR genomic targets and immunocapture RT-PCR sometimes reduced, but did not eliminate, the discrepancy between loss of infectivity and loss of RT-PCR titre. Virus presence based on RT-PCR detection must be interpreted with caution when predicting human health risks.
The inactivation of enteric adenoviruses 40 and 41 by ultraviolet (UV) radiation was investigated and compared with poliovirus type 1 (strain LSc-2ab) and coliphages MS-2 and PRD-1. Purified stocks of the viruses were exposed to collimated ultraviolet radiation in a stirred reactor for a total dose of up to 140 mW s/cm2. The doses of UV to achieve a 90% inactivation of adenovirus 40, adenovirus 41, coliphages MS-2 and PRD-1 and poliovirus type 1 were 30, 23.6, 14, 8.7 and 4.1 mW s/cm2, respectively. Adenovirus 40 was significantly more resistant than coliphage MS-2 to UV irradiation (P < 0.01). Adenovirus 41 appeared slightly more sensitive than adenovirus 40, but the difference was not significant (P>0.05). The resistance of PRD-1 was less than MS-2 (P < 0.01), but greater than poliovirus type 1 (P < 0.01). Adenoviruses 40 and 41 were more resistant than Bacillus subtilis spores, often suggested as an indicator of UV light performance. The double-stranded DNA adenoviruses appear to be the most resistant of all potentially water-borne enteric viruses to UV light disinfection.
Resisting spam in tagging system is very challenging. This paper presents DSpam, a novel spam-resistant tagging system which can significantly diminish spam in tag search results with users' reliabilities. DSpam client groups other users into unfamiliar users and interacted users according to the fact whether the client has interacted with such users. For an unfamiliar user, the client computes his reliability by tagging behavior-based mechanism which reflects correlation of annotations between them. For an interacted user, the reliability includes two parts: feedback-based reliability, which indicates direct interactions between that user and the client, and recommendation reliability, which indicates the evaluation about that user from the client's friends. The client ranks search result with the average reliabilities of himself with respect to annotators of each result. Experimental results show DSpam can effectively resist tag spam and work better than existing tag search schemes.
User-supplied reviews are widely and increasingly used to enhance e- commerce and other websites. Because reviews can be numerous and varying in quality, it is important to assess how helpful each review is. While review helpfulness is currently assessed manu- ally, in this paper we consider the task of automatically assessing it. Experi- ments using SVM regression on a vari- ety of features over Amazon.com product reviews show promising results, with rank correlations of up to 0.66. We found that the most useful features in- clude the length of the review, its uni- grams, and its product rating.
Consumers have to often wade through a large number of on-line reviews in order to make an informed product choice. We introduce OPINE, an unsupervised, high-precision information extraction system which mines product reviews in order to build a model of product features and their evaluation by reviewers.
Web 2.0 technologies have enabled more and more people to freely comment on different kinds of entities (e.g. sellers, products, services). The large scale of information poses the need and challenge of automatic summarization. In many cases, each of the user-generated short comments comes with an overall rating. In this paper, we study the problem of generating a "rated aspect summary" of short comments, which is a decomposed view of the overall ratings for the major aspects so that a user could gain different perspectives towards the target entity. We formally define the problem and decompose the solution into three steps. We demonstrate the effectiveness of our methods by using eBay sellers' feedback comments. We also quantitatively evaluate each step of our methods and study how well human agree on such a summarization task. The proposed methods are quite general and can be used to generate rated aspect summary automatically given any collection of short comments each associated with an overall rating.
There has been growing concern over human exposure to adenoviruses through drinking water due to their apparent high resistance to UV irradiation and the anticipated widespread use of ultraviolet (UV) disinfection in drinking water treatment processes. However, most inactivation studies on adenoviruses were performed using only one type of UV technology--low-pressure (LP) UV, and little is known about the effectiveness of different UV technologies such as medium- pressure (MP) UV or other polychromatic UV technologies. In this work, the kinetics and extent of inactivation of a human adenovirus (adenovirus 2 (Ad2)) by both monochromatic LP and polychromatic MP UV were evaluated to determine the effectiveness of these UV technologies on human adenoviruses. Inactivation of Ad2 by LP UV was very slow and only 0.87 and 2.17 log(10) inactivation was achieved with UV doses of 30 and 90 mJ/cm(2), respectively. However, inactivation of Ad2 by MP UV was much faster and 2.19 and 5.36 log(10) inactivation was observed with the same UV doses (30 and 90 mJ/cm(2), respectively). It appears that MP UV is more effective against Ad2 than LP UV and the enhanced effectiveness of MP UV on Ad2 is likely due to its ability to inhibit the repair process in UV-irradiated Ad2.
Ultraviolet light action spectra in the range 2250 to 3020 A have been determined for the plaque-forming ability of the following bacteriophage and animal viruses: T-2, varphix-174, R-17, fr, MS2, 7-S, fd, vesicular stomatitis, vaccinia, encephalomyocarditis, reovirus-3, and polyoma. Absolute quantum yields for the plaque-forming ability of MS2, fr, fd, varphix-174, and T-2 were determined over the range 2250 to 3020 A. Relative quantum yields for plaque-forming ability indicated that viruses with single-stranded nucleic acid were on the average ten times more sensitive to UV than double-stranded viruses. In addition for ten of the twelve viruses a relation existed between the shape of their action spectra and the stranded state of their nucleic acid. The ratio of the inactivation cross-section at 2650 A to that at 2250 A for these viruses was 1.0 for single-stranded viruses and 2.0 for viruses with double-stranded nucleic acid. The above relations were dependent on the stranded state of the nucleic acid not the ribose or deoxyribose form of the sugar present.
Host cell interactions of human adenovirus serotypes belonging to subgroups B (adenovirus type 3 [Ad3] and Ad7) and C (Ad2 and Ad5) were comparatively analyzed at three levels: (i) binding of virus particles with host cell receptors; (ii) cointernalization of macromolecules with adenovirions; and (iii) adenovirus-induced cytoskeletal alterations. The association constants with human cell receptors were found to be similar for Ad2 and Ad3 (8 x 10(9) to 9 x 10(9) M-1), and the number of receptor sites per cell ranged from 5,000 (Ad2) to 7,000 (Ad3). Affinity blottings, competition experiments, and immunofluorescence stainings suggested that the receptor sites for adenovirus were distinct for members of subgroups B and C. Adenovirions increased the permeability of cells to macromolecules. We showed that this global effect could be divided into two distinct events: (i) cointernalization of macromolecules and virions into endocytotic vesicles, a phenomenon that occurred in a serotype-independent way, and (ii) release of macromolecules into the cytoplasm upon adenovirus-induced lysis of endosomal membranes. The latter process was found to be type specific and to require unaltered and infectious virus particles of serotype 2 or 5. Perinuclear condensation of the vimentin filament network was observed at early stages of infection with Ad2 or Ad5 but not with Ad3, Ad7, and noninfectious particles of Ad2 or Ad5, obtained by heat inactivation of wild-type virions or with the H2 ts1 mutant. This phenomenon appeared to be a cytological marker for cytoplasmic transit of infectious virions within adenovirus-infected cells. It could be experimentally dissociated from vimentin proteolysis, which was found to be serotype dependent, occurring only with members of subgroup C, regardless of the infectivity of the input virus.
The DNA repair capacities of five human tumor cell lines, one SV40-transformed human cell line and one adenovirus-transformed
human cell line were compared with that of normal human fibroblasts using a sensitive host cell reactivation (HCR) technique.
Unirradiated and UV-irradiated suspensions of adenovirus type 2 (Ad 2) were assayed for their ability to form viral structural
antigens (Vag) in the various cell types using immunofluorescent staining. The survival of Vag formation for UV-irradiated
Ad 2 was significantly reduced in all the human tumor cell lines and the SV40-transformed human line compared to the normal
human fibroblasts, but was apparently normal in the adenovirus-transformed human cells. D0 values for the UV survival of Ad 2 Vag synthesis in the tumor and virally transformed lines expressed as a percentage of
that obtained on normal fibroblast strains were used as a measure of DNA repair capacity. Percent HCR values ranged from 26
to 53% in the tumor cells. These results indicate a deficiency in the repair of UV-induced DNA damage associated with human
tumorigenesis and the transformation of human cells by SV40 but not the transformation of human cells by adenovirus.
Action spectra for the inactivation of virus infectivity by u.v. irradiation have shown peaks predominantly at wavelengths from 260 to 265 nm. Such results have been obtained for viruses containing both RNA and DNA: plant viruses, e.g. tobacco mosaic virus (Hollaender & Duggar, 1936; Kleczkowski, 1963), tobacco necrosis virus (Kassanis & Kleczkowski, 1965) and potato virus X (Kleczkowski & Govier, 1969); bacteriophages, e.g. T 1 and T 2 (Zelle & Hollaender, 1954; Fluke, 1956), T4D (Winkler, Johns & Kellenberger, 1962) and M 5 (Franklin, Friedman & Setlow, 1953); and animal viruses, e.g. vaccinia (Rivers & Gates, 1928), Rous sarcoma virus (Sturm, Gates & Murphy, 1932) and influenza virus (Hollaender & Oliphant, 1944; Tamm & Fluke, 1950). Rauth (1965) also compared action spectra for several animal and bacterial viruses.
Human adenovirus type 2 was irradiated with U.V.-light, and the radiosensitivity of several viral functions was determined and correlated with the damage in the viral DNA. The D37 for plaque formation and clone inhibition was found to be 2·1 × 103 erg/mm3 and 6·4 × 103 erg/mm2, respectively. Thymine dimers, cross-links and single-strand breaks were detected in the viral DNA. The fraction of thymine present as dimer was 1·9 × 10−6/erg/mm2, and the number of U.V. induced single-strand breaks was 21/erg/mm2/1012 daltons. An average of 30 dimers and one single-strand break were induced per lethal hit as measured by plaque formation. The addition of caffeine to the plaquing medium was found to reduce the survival of U.V.-irradiated virus, suggesting the possibility of a host-mediated repair mechanism.
SUMMARY Cell strains established from fibroblasts of 10 normal persons, 12 persons afflicted with xeroderma pigmentosum (XP), and 4 XP hétérozygotes have been used as hosts in studies on the repair of ultraviolet-irradiated human adeno- virus 2. The virus appeared most ultraviolet light sensitive when strains belonging to XP complementation Groups A and D were used as hosts, less sensitive when strains belonging to Groups B and C were used, and least sensitive when normal or heterozygous strains were used. One-hit inactivation of adenovirus 2 required fluences of 7 to 15, 25 to 78, and 222 J/sq m, respectively, in each of these three categories of cell strains. One XP strain, judged by other methods to be capable of normal repair, was found to have a 30% repair defect by the adenovirus repair assay.
Xeroderma pigmentosum (XP) is one of a number of autosomal recessive syndromes in humans characterized by a marked predisposition to cancer. Fibroblasts from these patients show a defect in DNA repair. The XP heterozygotes also show elevated skin cancer incidence, but reports concerning their DNA repair capacity are conflicting. In this study, the DNA repair capacity of four XP heterozygotes was examined using a sensitive host cell reactivation technique. Unirradiated and irradiated suspensions of adenovirus type 2 (Ad 2) were assayed for their ability to form viral structural antigens in fibroblasts from XP heterozygotes, XP homozygotes, and normals. A reduced host cell reactivation (of viral structural antigen production) for both ultraviolet- and gamma-irradiated Ad 2 was detected in four XP heterozygotes representing three different complementation groups as well as their XP homozygous children. The doses necessary to reduce the survival of viral structural antigen production by irradiated AD 2 to 37% in the XP heterozygous strains were expressed as a percentage of that obtained in normal strains and ranged from 55 to 82% for ultraviolet-irradiated Ad 2 and 71 to 79% for gamma-irradiated Ad 2. These results add further support to a direct relationship between cancer proneness and DNA repair defects and show the merits of this host cell reactivation technique in identifying XP heterozygotes. Identification of XP heterozygotes is of considerable public health interest not only in genetic counseling but also in the prevention of cancer.
Adenoviruses enter their host cells by receptor-mediated endocytosis and acid-activated penetration from endosomes into the cytosol and deliver their DNA genome into the nucleus. Our results show that incoming adenovirus type 2 particles undergo a stepwise disassembly program necessary to allow progress of the virus in the entry pathway and release of the genome into the nucleus. The fibers are released, the penton base structures dissociated, the proteins connecting the DNA to the inside surface of the capsid degraded or shed, and the capsid-stabilizing minor proteins eliminated. The uncoating process starts immediately upon endocytic uptake with the loss of fibers and ends with the uptake of dissociated hexon proteins and DNA into the nucleus.
A complementary DNA clone has been isolated that encodes a coxsackievirus and adenovirus receptor (CAR). When transfected
with CAR complementary DNA, nonpermissive hamster cells became susceptible to coxsackie B virus attachment and infection.
Furthermore, consistent with previous studies demonstrating that adenovirus infection depends on attachment of a viral fiber
to the target cell, CAR-transfected hamster cells bound adenovirus in a fiber-dependent fashion and showed a 100-fold increase
in susceptibility to virus-mediated gene transfer. Identification of CAR as a receptor for these two unrelated and structurally
distinct viral pathogens is important for understanding viral pathogenesis and has implications for therapeutic gene delivery
with adenovirus vectors.
A variety of biophysical techniques have been employed to examine the size and conformational integrity of highly purified hepatitis A virus (HAV) in solution (purified HAV particles are subsequently formalin-inactivated and adsorbed to aluminum salts for use as the vaccine VAQTA). The size of HAV particles was assessed by a combination of electron microscopy, sedimentation velocity, and dynamic light scattering. The effect of ionic strength and temperature on the overall conformational stability of HAV was determined by a combination of intrinsic HAV protein fluorescence, fluorescent probes of both RNA and protein, and UV-visible spectroscopy. A major structural change in HAV occurs near 60 degrees C with the addition of 0.2 M magnesium chloride enhancing the thermal stability of HAV by approximately 10 degrees C. Salt concentrations above 0.2 M, however, decrease the solubility of HAV. The effect of pH on the physical properties of HAV particles was monitored by dynamic light scattering, analytical size exclusion HPLC, and interaction with fluorescent dyes. HAV particles undergo a substantially reversible association/aggregation at pH values below 6 with the concomitant exposure of previously buried hydrophobic surfaces below pH 4. These results are in good agreement with previous studies of HAV thermal stability under extreme conditions in which the irreversible inactivation of the viral particles was measured primarily by the loss of viral infectivity. The wide variety of biophysical measurements described in this work, however, directly monitor structural changes as they occur, thus providing a molecular basis with which to monitor HAV stability during purification and storage.
Bacteriophage T4 DNA metabolism is largely insulated from that of its host, although some host functions assist in the repair of T4 DNA damage. Environmental factors sometimes affect survival and mutagenesis after ultraviolet (UV) irradiation of T4, and can affect mutagenesis in many organisms. We therefore tested the effect of certain environmental factors and host genetic defects upon spontaneous and UV-induced mutagenesis and survival in T4 and some related T-even phages. Plating at pH 9 enhances UV resistance in T4 by about 14% compared to pH 7. The host cAMP regulatory system affects host survival after UV irradiation but does not affect T4 survival. Thermal rescue, the increasing survival of irradiated T4 with increasing plating temperature, occurs also in phage T6, but only weakly in phages T2 and RB69; this temperature effect is not altered by supplementing infected cells with additional Holliday resolvase (gp49) early in infection. Phage RB69 turns out to have almost 50% greater UV resistance than T4, but has a genome of about the same size; RB69 is UV-mutable but does not produce r mutants, which are easily seen in T2, T4, and T6. Spontaneous mutagenesis in T4 shows no dependence on medium and little dependence on temperature overall, but mutation rates can increase and probably decrease with temperature at specific sites. UV mutagenesis is not affected by incubating irradiated particles under various conditions before plating, in contrast to phage S13.
The action of adenoviral E1A oncoprotein on host immune-response genes has been attributed to interaction with p300/CBP-type transcriptional coactivators in competition with endogenous transcription factors such as signal transducer and activator of transcription (STAT) proteins. However, we show that mutant forms of E1A that no longer bind p300/CBP can still interact directly with Stat1 (via E1A N-terminal and Stat1 C-terminal residues) and block IFNgamma-driven, Stat1-dependent gene activation and consequent function during early-phase infection in the natural host cell. The results provide a distinct and more specific mechanism for E1A-mediated immune suppression and an alternative model of IFNgamma-driven enhanceosome formation that may allow for other adaptors (in addition to p300/CBP) to link Stat1 to the basal transcription complex.
We have been developing a rapid and convenient assay for the measurement of DNA damage and repair in specific genes using quantitative polymerase chain reaction (QPCR) methodology. Since the sensitivity of this assay is limited to the size of the DNA amplification fragment, conditions have been found for the quantitative generation of PCR fragments from human genomic DNA in the range of 6-24 kb in length. These fragments include: (1) a 16.2 kb product from the mitochondrial genome; (2) 6.2, 10.4 kb, and 15.4 kb products from the hprt gene, and (3) 13.5, 17.7, 24.2 kb products from the human beta-globin gene cluster. Exposure of SV40 transformed human fibroblasts to increasing fluences of ultraviolet light (UV) resulted in the linear production of photoproducts with 10 J/m(2) of UVC producing 0.085 and 0.079 lesions/kb in the hprt gene and the beta-globin gene cluster, respectively. Kinetic analysis of repair following 10 J/m(2) of UVC exposure indicated that the time necessary for the removal of 50% of the photoproducts, in the hprt gene and beta-globin gene cluster was 7.8 and 24.2 h, respectively. Studies using lymphoblastoid cell lines show very little repair in XPA cells in both the hprt gene and beta-globin locus. Preferential repair in the hprt gene was detected in XPC cells. Cisplatin lesions were also detected using this method and showed slower rates of repair than UV-induced photoproducts. These data indicate that the use of long targets in the gene-specific QPCR assay allows the measurement of biologically relevant lesion frequencies in 5-30 ng of genomic DNA. This assay will be useful for the measurement of human exposure to genotoxic agents and the determination of human repair capacity.
The effect of ultraviolet radiation from low- and medium-pressure mercury arc lamps on Cryptosporidium parvum oocysts was studied using a collimated beam apparatus. Experiments were conducted using parasites suspended in both filtered surface water and phosphate buffered laboratory water. Inactivation of oocysts was measured as reduction in infectivity using a CD-1 neonatal mouse model and was found to be a non-linear function of UV dose over the range of germicidal doses tested (0.8-119 mJ/cm2). Oocyst inactivation increased rapidly with UV dose at doses less than 25 mJ/cm2 with two and three log-units inactivation at approximately 10 and 25 mJ/cm2, respectively. The cause of significant leveling-off and tailing in the UV inactivation curve at higher doses was not determined. Maximum measured oocyst inactivation ranged from 3.4 to greater than 4.9 log-units and was dependent on different batches of parasites. Water type and temperature, the concentration of oocysts in the suspension, and the UV irradiance did not have significant impacts on oocyst inactivation. When compared on the basis of germicidal UV dose, the oocysts were equally sensitive to low- and medium-pressure UV radiation. With respect to Cryptosporidium, both low- and medium-pressure ultraviolet radiation are attractive alternatives to conventional chemical disinfection methods in drinking water treatment.