Norman arthur Ratcliffe

Norman arthur Ratcliffe
Swansea University | SWAN

BSc, PhD, DSc.

About

228
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Publications

Publications (228)
Article
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This overview initially describes insect immune reactions and then brings together present knowledge of the interactions of vector insects with their invading parasites and pathogens. It is a way of introducing this Special Issue with subsequent papers presenting the latest details of these interactions in each particular group of vectors. Hopefull...
Preprint
Full-text available
This overview initially describes insect immune reactions and then brings together present knowledge of the interactions of vector insects with their invading parasites and pathogens. It is a way of introducing this special issue with subsequent papers presenting the latest details of these interactions in each particular group of vectors. Hopefull...
Article
Full-text available
Introduction. There is an urgent need to source new compounds that can combat the current threat of serious infection caused by Candida spp. and contend with the problem of antimicrobial resistance. Gap. A synthesis of the evidence available from the current literature is needed to identify promising antifungal chemotherapeutics. Aim. To highlight...
Chapter
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Environmental changes can always influence the individual fitness and enhance the performance of any living organism. However, some environmental changes are more beneficial than others. In this chapter, we will address concepts of phenotypic plasticity through the point of view of plant physiology, especially in two species of the genus Plectranth...
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Despite intramuscular vaccines saving millions of lives, constant devastating waves of SARS-CoV-2 infections continue. The elimination of COVID-19 is challenging, but necessary in order to avoid millions more people who would suffer from long COVID if we fail. Our paper describes rapidly advancing and innovative therapeutic strategies for the early...
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Several scientific studies to evaluate the process of digestion and fractionation of immunoglobulins have been carried out in order to improve the production of hyperimmune sera. Today, quality, safety, and production efficiency, along with the development of optimized, robust, and cost-effective processes are priorities. Thus, this work analyzed p...
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Background Microbial resistance has become a worldwide public health problem, and may lead to morbidity and mortality in affected patients. Objective Therefore, this work aimed to evaluate the antibacterial activity of quinone-4-oxoquinoline derivatives. Method These derivatives were evaluated against Gram-positive and Gram-negative bacteria by t...
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This article presents an overview of paratransgenesis as a strategy to control pathogen transmission by insect vectors. It first briefly summarises some of the disease-causing pathogens vectored by insects and emphasises the need for innovative control methods to counter the threat of resistance by both the vector insect to pesticides and the patho...
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Introduction: The search for an animal model capable of reproducing the physiopathology of the COVID-19, and also suitable for evaluating the efficacy and safety of new drugs has become a challenge for many researchers. Areas covered: This work reviews the current animal models for in vivo tests with SARS-CoV-2 as well as the challenges involved...
Article
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Since the very beginning of the COVID-19 pandemic, different treatment strategies have been explored. These mainly involve the development of antimicrobial, antiviral, and/or anti-inflammatory agents as well as vaccine production. However, other potential options should be more avidly investigated since vaccine production on a worldwide level, and...
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The COVID-19 pandemic has had catastrophic Global effects on financial markets, jobs and peoples’ lives. Future prevention/therapy of COVID-19 will rely heavily on vaccine development and attempts to repurpose drugs previously used for other microbial diseases. Little attention, however, has been paid to possible difficulties and delays in producin...
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Agricultural crops need protection from a variety of different insects popularly known as pests. Some of these pests are becoming increasingly resistant to conventional pesticides, so new control alternatives are needed. In this work, the effects of the essential oil of the plant Zanthoxylum caribaeum on the development of cotton stink bug Dysdercu...
Article
Background Siderophores are small molecule iron-chelators produced by microorganisms and plants growing mostly under low iron conditions. Siderophores allow iron capture and transport through cell membranes into the cytoplasm, where iron is released for use in biological processes. These bacterial iron uptake systems can be used for antibiotic conj...
Article
Artículo Original | Original Article 555 Chemical composition and acaricidal activity of Ocotea notata (Lauraceae), an endemic species from Brazil, against the cattle tick Rhipicephalus microplus [Composición química y actividad acaricida de Ocotea notata (Lauraceae), una especie endémica de Brasil, contra la garrapata del ganado Rhipicephalus micr...
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Chikungunya virus (CHIKV) infection is one of the most challenging re-emergent diseases caused by a virus, and with no specific antiviral treatment it has now become a major public health concern. In this investigation, 25 blood samples were collected from patients with characteristic CHIKV symptoms and submitted to a virus isolation protocol, whic...
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Dengue, yellow fever, Zika, and chikungunya arboviruses are endemic in tropical countries and are transmitted by Aedes aegypti. Resistant populations of this mosquito against chemical insecticides are spreading worldwide. This study aimed to evaluate the biological effects of exposure of pesticide-sensitive Ae. aegypti larvae (Rockefeller) to conid...
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Zika virus (ZIKV) is a mosquito-borne pathogen which is a current global public health concern. There are currently no approved vaccines or antivirals against ZIKV infection. Taking into account that naphthoquinones have shown promising antiviral activity, the aim of this study was to describe the screening of two bis-naphthoquinones series against...
Article
The main strategy of interrupting Trypanossoma cruzi transmission is to control the vector populations. Studies of new agents with activity against these vectors have a priority interest. This study evaluated the insecticidal activity of the essential oil of Myrciaria floribunda against nymphs of R. prolixus. M. floribunda was collected in Jurubati...
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Rhodnius prolixus is an insect vector of Trypanosoma cruzi, the causative agent of Chagas disease in Latin America. Nuclear factor-κB (NF-κB) transcription factors (TF) are conserved components of the innate immune system in several multicellular organisms including insects. The drug IMD-0354 (N-(3,5-bis-trifluoromethyl-phenyl)-5-chloro-2-hydroxy-b...
Article
This review summarizes the reported molecular mechanisms underlying the antileukemic property of Sesquiterpene Lactones (SLs). This systematic review was registered in the PROSPERO database and conducted following the PRISMA Statements. The MeSH terms, Sesquiterpenes, Lactones and Leukemia were used in four databases (Pubmed, Web of Science, Scopus...
Article
The Aedes aegypti mosquito is one of the major vectors of arboviruses. These diseases have re-emerged and the insecticides used nowadays are toxic to mammals and environment and have only been effective in the short-term. In this context, natural products are an alternative. The genus Piper has many active compounds against arthropods, including ne...
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The effects of the hexanic extracts of the fruits and flowers of Clusia fluminensis Planch. & Triana, Clu-siaceae, as well as their main constituents, the triterpene lanosterol and the benzophenone clusianone, were evaluated on hemipterans Dysdercus peruvianus and Oncopeltus fasciatus. The topical treatments of insects with the hexanic extracts sig...
Article
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Evolution of the insect immune system led to the creation of a comprehensive cellular defense system, not only involving phagocytosis, but also encapsulation and nodulation (both often referred to as capsule formation) allowing the isolation and neutralization of invading pathogens and parasites. Such reactions are closely related to the anatomical...
Article
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Although many insects successfully live in dangerous environments exposed to diverse communities of microbes, they are often exploited and killed by specialist pathogens. Studies of host-pathogen interactions (HPI) provide valuable insights into the dynamics of the highly aggressive coevolutionary arms race between entomopathogenic fungi (EPF) and...
Article
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Studies evaluated the effects of hexanic extracts from the fruits and flowers of Clusia fluminensis and the main component of the flower extract, a purified benzophenone (clusianone), against Aedes aegypti. The treatment of larvae with the crude fruit or flower extracts from C. fluminensis did not affect the survival of Ae. aegypti (50 mg/L), howev...
Article
Leprosy is a chronic granulomatous disease caused by Mycobacterium leprae affecting the skin and peripheral nerves. Despite M. leprae invasion of the skin and keratinocytes importance in innate immunity, the interaction of these cells in vitro during M. leprae infection is poorly understood. Conventional and fuorescence optical microscopy, transmis...
Article
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Background The triatomine, Rhodnius prolixus, is a major vector of Trypanosoma cruzi, the causative agent of Chagas disease in Latin America. It has a strictly blood-sucking habit in all life stages, ingesting large amounts of blood from vertebrate hosts from which it can acquire pathogenic microorganisms. In this context, the production of antimic...
Article
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Except for honey as food, and silk for clothing and pollination of plants, people give little thought to the benefits of insects in their lives. This overview briefly describes significant recent advances in developing insect natural products as potential new medicinal drugs. This is an exciting and rapidly expanding new field since insects are hug...
Article
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Chagas disease kills 2.5 thousand people per year of 15 million persons infected in Latin America. The disease is caused by the protozoan, Trypanosome cruzi, and vectored by triatomine insects, including Panstrongylus megistus, an important vector in Brazil. Medicines treating Chagas disease have unpleasant side effects and may be ineffective, ther...
Article
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Candida albicans is a major human pathogen whose treatment is challenging due to antifungal drug toxicity, drug resistance and paucity of antifungal agents available. Myrocin (MYR) inhibits sphingosine synthesis, a precursor of sphingolipids, an important cell membrane and signaling molecule component. MYR also has dual immune suppressive and antif...
Article
Background: Studies were carried out to evaluate the effects of Manilkara subsericea extracts and triterpenes on the development of two species of agricultural pest insects, Oncopelus fasciatus and Dysdercus peruvianus. Results: All treatments of insects with M. subsericea extracts induced mortality, delayed development and inhibited moulting. S...
Article
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Trypanosoma cruzi in order to complete its development in the digestive tract of Rhodnius prolixus needs to overcome the immune reactions and microbiota trypanolytic activity of the gut. We demonstrate that in R. prolixus following infection with epimastigotes of Trypanosoma cruzi clone Dm28c and, in comparison with uninfected control insects, the...
Article
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In this overview, some of the more significant recent developments in bioengineering natural products from insects with use or potential use in modern medicine are described, as well as in utilisation of insects as models for studying essential mammalian processes such as immune responses to pathogens. To date, insects have been relatively neglecte...
Article
Maggot therapy, utilizing the larvae of Lucilia sericata, has been reported to reduce the bacterial load within wounds and also to enhance wound healing. Maggot excretions/secretions (ES) have been shown to have a role in the success of maggot therapy. While the protein content of ES has been investigated, to date little research has focused on the...
Article
Chronic infections are commonly associated with biofilms formed by bacteria such as Staphylococcus epidermidis. With the increase in antibiotic resistant bacteria, maggot debridement therapy has been reintroduced for the treatment of chronic wounds. Studies have shown that the excretion/secretions (ES) of Lucilia sericata larvae (maggots) contain m...
Article
Associated with the female insect reproductive system are a number of glands. Those present in Nasonia vitripennis are described, their microanatomy examined and where possible this is linked with their function during the process of drilling into the host puparium, feeding on the host fluids and oviposition. The structures dealt with are the ovari...
Article
S ynopsis An account is given of the formation of the egg membranes of Apanteles glomeratus , and their structure is compared with that found in other insects.
Article
S ynopsis The structure of the acid and alkaline glands of Nasonia vitripennis is described, and the method by which the secretions of the acid gland are transferred to the ovipositor is discussed.
Article
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The 'Sea Empress' oil tanker grounded outside Milford Haven (Wales, UK) in February 1996, spilling ~70,000 tonnes of crude oil and contaminating over 100 km of coastline, causing mass mortalities and strandings of at least 11 mollusc species. Intensive field monitoring commenced after the spill, examining immunity and hydrocarbon levels in the muss...
Article
RNA interference is a post-transcriptional mode of gene silencing that works as acellular response to gene invasion resulting from transposons or viruses. Silencing occursby a double-stranded RNA (homologous to the silenced gene) targeting and degradingthe mRNA. To date, RNAi has been applied to a number of studies involved in insectimmunity, such...
Article
The present review considers the structure, site of formation and functions of protochordate blood cells/coelomocytes. Details of the circulatory and coelomic system are also given where appropriate. In the hemichordates, blood cells are absent but a single type of amoebocyte is present in the coelomic cavity. A similar situation exists in cephaloc...
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The spatial heterogeneity of questing Ixodes ricinus (L.) (Acari: Ixodidae) within endemic areas in Great Britain is well established. Their presence is acutely responsive to blood host availability and their ability to maintain water balance, which are in turn governed by a variety of ecological and environmental factors. This article details the...
Article
The application of Lucilia sericata larvae to chronic, infected wounds results in the rapid elimination of infecting microorganisms, including MRSA. Previously, we demonstrated in vitro antibacterial activity of native excretions/secretions (nES) from L. sericata and partially purified two low mass antibacterial compounds with masses of 0.5-10kDa a...
Article
Nitric oxide (NO) is a key immune effector and signaling molecule in many organisms. However, the contribution NO makes towards insect immunity has received little attention, particularly in non-dipteran species. In this study, tissue- and time-specific alterations in NO synthase (NOS) gene expression and NO production were documented in the hemipt...
Article
Members of the subfamily Triatominae, family Reduviidae, comprise a large number of insect species of which some are vectors of Trypanosoma cruzi, the causative agent of Chagas' disease. This article outlines research on the process of transformation and the dynamics of developmental stages of Trypanosoma cruzi in the triatomine insect hosts. Speci...
Article
Antiserum raised against Rhodnius prolixus perimicrovillar membranes (PMM) and midgut tissue interfered with the midgut structural organization and reduced the development of Trypanosoma cruzi in the R. prolixus insect vector. SDS-PAGE and Western blot analyses confirmed the specific recognition of midgut proteins by the antibody. Feeding, mortalit...
Article
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Maggot therapy employs the use of freshly emerged, sterile larvae of the common green-bottle fly, Phaenicia (Lucilia) sericata, and is a form of artificially induced myiasis in a controlled clinical situation. Maggot therapy has the following three core beneficial effects on a wound: debridement, disinfection and enhanced healing. In part II of thi...
Article
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It is now a universally acknowledged fact that maggot therapy can be used successfully to treat chronic, long-standing, infected wounds, which have previously failed to respond to conventional treatment. Such wounds are typically characterized by the presence of necrotic tissue, underlying infection and poor healing. Maggot therapy employs the use...
Article
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In invertebrates, encapsulation is the common immune defence reaction towards foreign bodies, including multicellular parasites, which enter the haemocoel and are too large to be phagocytosed. This immune response has been most extensively studied in insects, in which it is highly complex, involving a diversity of cellular and molecular processes,...
Article
In the gut of some insect vectors, parasites ingested with the bloodmeal decrease in number before coming into contact with host tissues. Many factors could be responsible for this reduction in parasite number but the potentially important role of the large communities of naturally occurring microorganisms that exist alongside the newly ingested pa...
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This review outlines aspects on the developmental stages of Trypanosoma cruzi and Trypanosoma rangeli in the invertebrate host, Rhodnius prolixus. Special attention is given to the interactions of these parasites with gut and hemolymph molecules and the effects of the organization of midgut epithelial cells on the parasite development. The vector i...
Article
Maggot therapy is a simple and highly successful method for cleansing infected and necrotic wounds. The use of maggots has become increasingly important in the treatment of non-healing wounds, particularly those infected with the multidrug-resistant pathogen, methicillin-resistant Staphylococcus aureus (MRSA). The increasing challenge concerning th...
Article
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Lipoproteins and molecules for pattern recognition are centrally important in the innate immune response of both vertebrates and invertebrates. Mammalian apolipoproteins such as apolipoprotein E (apoE) are involved in LPS detoxification, phagocytosis, and possibly pattern recognition. The multifunctional insect protein, apolipophorin III (apoLp-III...
Article
There is growing evidence that contaminants may be partly responsible for the observed increase in disease in marine organisms by adversely affecting their immunity. Bivalve molluscs are common sentinels used in invertebrate immunotoxicology, however, to date, studies have been restricted to a few resilient species. This present study is a comparat...
Article
Much of the current knowledge concerning bivalve immunology and immunotoxicology has come from studies on the mussel genus, Mytilus, or from the American oyster, Crassostrea virginica. Following a major oil spill, it was observed that the marine mussel, Mytilus edulis, underwent significant immunosuppression but no oil-induced mortalities, while in...
Article
To investigate the molecular mechanism of the early-stage encapsulation reaction in insects, we purified a 47kDa protein from injected beads into Galleria mellonella larvae. When a cDNA clone was isolated, the 47kDa protein showed high homology with Drosophila and human calreticulin. Western blotting analysis showed that the 47kDa protein was prese...
Article
In the present study, FITC-labelled lectins (WGA, Con A, PNA, HPA, and TPA) were utilized to investigate carbohydrate residues on the surface of Rhodnius prolixus salivary glands. The results revealed that the salivary glands are rich in carbohydrate moieties and the diversity in binding pattern of particular lectins showed the presence of specific...
Article
This study compares aspects of the superoxide, nitric oxide and prophenoloxidase pathways in Rhodnius prolixus hemolymph, measured in parallel, in response to Trypanosoma rangeli inoculation. Responses to two strains of T. rangeli, and two developmental forms, were studied, and the results obtained were correlated with the ability of the parasites...
Article
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In February 1996, the oil tanker ‘Sea Empress’ spilt over 70 000 t of crude oil which contaminated ca 200 km of coastline (Milford Haven, Wales, UK). The effects of the oil on immunity in mussels Mytilus edulis were investigated in parallel with the measurement of hydrocarbon contamination in the tissues. Initially, severe immunosuppression occurre...
Article
Lysozyme-like activity has been demonstrated in both cell-free haemolymph and, more abundantly, in haemocyte-lysate supernatants of Blaberus discoidalis. This activity was non-inducible, but heat-stable, with a maximum activity at pH 6.2. When B. cereus was pre-incubated in a concentration of chicken egg-white lysozyme equivalent to the concentrati...
Article
The respiratory burst is an NADPH oxidase-driven reduction of molecular oxygen to superoxide, which can occur in phagocytic cells as part of an antimicrobial defence, and is well documented among the vertebrates. This paper describes a process resembling the respiratory burst, which occurs in the haemolymph and haemocytes of the cockroach, Blaberus...
Article
We demonstrated that in Rhodnius prolixus haemocyte monolayers, both Trypanosoma cruzi and Trypanosoma rangeli are capable of inducing haemocyte/parasite clump formation. We also purified, by one-step affinity chromatography, a haemolymph galactoside-binding lectin from R. prolixus which we believe could play an important role in the development of...