James Versalovic

James Versalovic
Baylor College of Medicine | BCM · Department of Pathology & Immunology

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87
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Publications

Publications (87)
Article
Full-text available
Background Interleukin (IL)-8 is the key agent for initiating an inflammatory response to infection with Helicobacter pylori. Some strains of Lactobacillus spp. are known to colonize the stomach and suppress inflammation caused by H. pylori. In this study, we characterized two gastric-derived lactobacilli, Lactobacillus salivarius (LS) strains B37...
Article
Objective: There is a dearth of biospecimen repositories available to perinatal researchers. In order to address this need, here we describe the methodology used to establish such a resource. Study design: With the collaboration of MedSci.net, we generated an online perinatal database with 847 fields of clinical information. Simultaneously, we e...
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Background: Recurrent abdominal pain is a common and costly health-care problem attributed, in part, to visceral hypersensitivity. Increasing evidence suggests that gut bacteria contribute to abdominal pain perception by modulating the microbiome-gut-brain axis. However, specific microbial signals remain poorly defined. γ-aminobutyric acid (GABA)...
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The gut microbiome may modulate intestinal immunity by luminal conversion of dietary amino acids to biologically active signals. The model probiotic organism Lactobacillus reuteri ATCC PTA 6475 is indigenous to the human microbiome, and converts the amino acid L-histidine to the biogenic amine, histamine. Histamine suppresses tumor necrosis factor...
Article
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Human microbiome-derived strains of Lactobacillus reuteri potently suppress proinflammatory cytokines like human tumor necrosis factor (TNF) by converting the amino acid l-histidine to the biogenic amine histamine. Histamine suppresses mitogen-activated protein (MAP) kinase activation and cytokine production by signaling via histamine receptor type...
Article
Rothia mucilaginosa is a gram-positive coccus that poses a diagnostic challenge and often requires DNA pyrosequencing for diagnosis as it can be easily mistaken for coagulase-negative staphylococci on initial culture results. While it is often times normal human oral and upper respiratory tract microbiota, it can be a virulent pathogen in immunocom...
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Obesity, metabolic syndrome, and type 2 diabetes are major public health challenges. Recently, interest has surged regarding the possible role of the intestinal microbiota as potential novel contributors to the increased prevalence of these 3 disorders. Recent advances in microbial DNA sequencing technologies have resulted in the widespread applica...
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DECREASED CONSUMPTION OF DIETARY FIBERS, SUCH AS CELLULOSE, HAS BEEN PROPOSED TO PROMOTE THE EMERGENCE OF INFLAMMATORY BOWEL DISEASES (IBD: Crohn disease [CD] and ulcerative colitis [UC]) where intestinal microbes are recognized to play an etiologic role. However, it is not known if transient fiber consumption during critical developmental periods...
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The Human Microbiome Project used rigorous good clinical practice standards to complete comprehensive body site sampling in healthy 18- to 40-yr-old adults, creating an unparalleled reference set of microbiome specimens. To ensure that specimens represented minimally perturbed microbiomes, we first screened potential participants using exclusion cr...
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Study of ethical, legal, and social implications (ELSI) of human microbiome research has been integral to the Human Microbiome Project (HMP). This study explores core ELSI issues that arose during the first phase of the HMP from the perspective of individuals involved in the research. We conducted semi-structured in-depth interviews with investigat...
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Beneficial microbes and probiotics show promise for the treatment of pediatric gastrointestinal diseases. However, basic mechanisms of probiosis are not well understood, and most investigations have been performed in germ-free or microbiome-depleted animals. We sought to functionally characterize probiotichost interactions in the context of normal...
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The human body is home to more than 1 trillion microbes, with the gastrointestinal tract alone harboring a diverse array of commensal microbes that are believed to contribute to host nutrition, developmental regulation of intestinal angiogenesis, protection from pathogens, and development of the immune response. Recent advances in genome sequencing...
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The connection between intestinal microbiota and host physiology is increasingly becoming recognized. The details of this dynamic interaction, however, remain to be explored. Toll-like receptor 2 (Tlr2) is important for its role in bacterial recognition, intestinal inflammation, and obesity-related metabolic changes. Therefore, we sought to determi...
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Mammals are complex assemblages of mammalian and bacterial cells organized into functional organs, tissues, and cellular communities. Human biology can no longer concern itself only with human cells: Microbiomes at different body sites and functional metagenomics must be considered part of systems biology. The emergence of metagenomics has resulted...
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Full-text available
The Human Microbiome and Recurrent Abdominal Pain in Children
Article
Helicobacter pylori infection is associated with a variety of diseases including gastric cancer. Flavodoxin is an electron transfer protein containing a flavin mononucleotide prosthetic group and substituted an iron-containing electron transfer protein under iron-limiting conditions. H. pylori flavodoxin has been reported but its pathogenic role is...
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The early days of the genomic revolution—from the Asilomar Conference on Recombinant DNA in 1975 to the founding of the Human Genome Project in 1990—were marked by awareness among researchers, government officials, and policy makers that emerging scientific knowledge raised a host of ethical, legal, and social challenges. Scientists now undertaking...
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Steady advances in our knowledge of the composition and function of the human microbiome at multiple body sites including the gut, skin and airways will likely contribute to our understanding of mechanisms of probiotic action by beneficial microbes. Microbe:microbe and microbe:human interactions are important considerations as we select probiotics...
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Molecular pathology is a rapidly growing area of laboratory medicine in which DNA and RNA are analyzed. The recent introduction of array technology has added another layer of complexity involving massive parallel analysis of multiple genes, transcripts, or proteins. As molecular technologies are increasingly implemented in clinical settings, it is...
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Context.—Molecular pathology is a rapidly growing area of laboratory medicine in which DNA and RNA are analyzed. The recent introduction of array technology has added another layer of complexity involving massive parallel analysis of multiple genes, transcripts, or proteins. Objective.—As molecular technologies are increasingly implemented in clini...
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After Hurricane Katrina, an estimated 200,000 persons were evacuated to the Houston metropolitan area, >27,000 of whom were housed in 1 large "megashelter," the Reliant Park Complex. We investigated an outbreak of gastroenteritis reported among the evacuees who resided in the Reliant Park Complex to assess the spread of the infectious agent, norovi...
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Probiotics, live microorganisms administered to improve health, interact in as yet poorly understood ways with the complex microbial communities that inhabit the human host.
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We sought to compare the impact of antimicrobial impregnation to that of tunneling of long-term central venous catheters on the rates of catheter colonization and catheter-related bloodstream infection. Tunneling of catheters constitutes a standard of care for preventing infections associated with long-term vascular access. Although antimicrobial c...
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Lactobacilli represent components of the commensal mammalian gastrointestinal microbiota and are useful as probiotics, functional foods, and dairy products. This study includes systematic polyphasic analyses of murine intestinal Lactobacillus isolates and correlation of taxonomic findings with data from cytokine production assays. Lactobacilli were...
Article
This review describes a case of an HIV‐infected individual that conveys important lessons for the use of molecular methods in medical microbiology. The practical roles of viral load testing and genotyping (resistance testing) are discussed in the context of patient diagnosis and management.
Article
Helicobacter pylori represents one of the most common and medically prominent infections worldwide. Infection with this microaerobic, gram-negative bacterium has been established as an etiologic factor in the development of peptic ulcer disease. In addition, H pylori infection has been associated firmly with the development of gastric neoplasia, in...
Article
HIV-1 infection continues to present diagnostic and management challenges on a global scale. Multiple testing strategies currently are used for evaluation of patients and infection status. Serologic testing represents the standard for diagnosis of HIV-1 infection. Molecular methods enable screening of the blood supply, detection of vertical transmi...
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One hundred twenty-six urease-negative gastric biopsy specimens were evaluated for the presence of Helicobacter genus-specific 16S ribosomal DNA (rDNA) and H. pylori-specific glmM DNA sequences by PCR. The species specificity of the glmM PCR assay was demonstrated, as H. pylori was the only Helicobacter species that yielded the expected glmM amplic...
Article
Borreliosis, ehrlichiosis, and babesiosis are three tick-borne diseases found in the northeastern United States. This article reviews the causative agents, clinical symptoms, and transmission of these entities, as well as how they are diagnosed in the clinical laboratory. These diseases can have similar and overlapping symptoms, and cases of coinfe...
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The logistical details for organizing effective interpretive rounds in a laboratory medicine subspecialty must be carefully established so that expert opinions are provided in a timely fashion in a patient-specific report, rather than as a collection of fixed comments associated with a particular laboratory result generated by a computer This repor...
Article
This article has no abstract; the first 100 words appear below. Presentation of Case A 64-year-old man was admitted to the hospital because of fever and bacteremia. The patient had had hypertension for 20 years, type 2 diabetes mellitus for 16 years, and coronary disease for 7 years, with a history of myocardial infarction and congestive heart fail...
Article
To evaluate simultaneous diagnosis of infection and molecular resistance testing of Helicobacter pylori. Gastric biopsies were obtained from 26 rapid urease-positive and 51 rapid urease-negative test kits used to diagnose H pylori infection. Following glass bead-assisted DNA isolation, amplification of H pylori 16S ribosomal DNA (rDNA), glmM, and 2...
Article
In Helicobacter pylori, the oxygen-insensitive nitroreductase RdxA is likely to activate metronidazole (Mtz) by reduction and formation of cytotoxic intermediates. Mutations in rdxA have been associated with Mtz resistance in H. pylori. In vitro Mtz susceptibilities of 17 randomly selected H. pylori isolates were determined by the agar dilution met...
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A novel helicobacter with the proposed name Helicobacter aurati (type strain MIT 97-5075c) has been isolated from the inflamed stomachs and ceca of adult Syrian hamsters. The new species is fusiform with multiple bipolar sheathed flagella and periplasmic fibers; it contains urease and gamma-glutamyl transpeptidase. By 16S rRNA sequencing and repeti...
Article
This article has no abstract; the first 100 words appear below. Presentation of Case A 42-year-old asplenic man was admitted to the hospital because of gram-negative sepsis. The patient had been well until one week earlier, when his left upper teeth began to ache. Four days before admission, he had abdominal cramps and two loose stools. The next mo...
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Fifty-four of 59 (91.5%) clarithromycin-resistant isolates of Helicobacter pylori from different patients possessed either the A2143G (formerly A2058G) or the A2144G (formerly A2059G) mutation in the gene encoding 23S rRNA. The A2143G mutation was significantly more likely to occur in isolates with MICs exceeding 64 mg/L (65% versus 30% with the A2...
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We have developed a rapid PCR-oligonucleotide ligation assay that can discriminate single base substitu- tions that are associated with clarithromycin resistance in Helicobacter pylori. Susceptible isolates were wild type at positions 2143 and 2144 (cognate to 2058 and 2059 in Escherichia coli), while 93% of the resistant isolates contained A-to-G...
Article
Isogenic dnaG strains of Escherichia coli with the parB and dnaG2903 alleles in the MG1655 chromosomal background displayed the classic par phenotype at the nonpermissive temperature of 42 degrees C. These strains synthesized DNA at 42 degrees C, but remained chromosome segregation defective as determined by cytology. A strain with the dnaG2903 all...
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The molecular typing of 81 pretreatment Helicobacter pylori isolates and the comparison of 18 pretreatment-posttreatment pairs is described by restriction fragment length polymorphism (RFLP) of the ureC gene. The results of our study show the extreme genomic diversity of H. pylori and indicate that infection by H. pylori in the United States does n...
Article
Transition mutations (A-G) at residue 2143, cognate to position 2058 in the Escherichia coli 23S rRNA gene, have been shown to confer resistance to macrolides in Helicobacter pylori. This study reports the finding that transversion mutations (A-C) can occur at 2143 as well. Three clarithromycin-resistant H. pylori isolated from three different pati...
Article
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Twelve clarithromycin-resistant Helicobacter pylori isolates (100% of resistant isolates examined) from seven different patients each contained an A-->G transition mutation within a conserved loop of 23S rRNA. A-->G transition mutations at positions cognate with Escherichia coli 23S rRNA positions 2058 and 2059 were identified. Clarithromycin-susce...
Article
Evolutionary conservation of an interspersed repetitive DNA sequence, BOX, from Streptococcus pneumoniae was investigated to explore the mosaic nature of these elements. BOX elements consist of various combinations of three subunits, boxA, boxB, and boxC. Eight oligonucleotide probes were designed based on consensus DNA sequences of boxA, boxB, and...
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To confirm the vertical transmission of Citrobacter diversus from a mother to her infant and to evaluate the epidemiologic usefulness of a new automated procedure for analysis of polymerase chain reaction (PCR)-generated DNA fingerprints. Repetitive element-based PCR (rep-PCR) analysis of C diversus isolates from the blood and amniotic fluid of a m...
Article
Helicobacter pylori infection is now accepted as the most common cause of chronic active gastritis and peptic ulcer disease. The etiologies of many infectious diseases have been attributed to specific or clonal strains of bacterial pathogens. Polymerase chain reaction (PCR) amplification of DNA between repetitive DNA sequences, REP elements (REP-PC...
Article
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Fluorophore-labeled oligonucleotide primers complementary to defined interspersed repetitive sequences conserved in diverse bacteria were used in the polymerase chain reaction to generate DNA fingerprint patterns from selected pathogenic bacteria. Fluorophore-enhanced, repetitive sequence-based polymerase chain reaction allowed discrimination betwe...
Article
Molecular techniques were used to study the epidemiology of infections due to Enterobacter aerogenes in a tertiary-care hospital. Sixty-two clinical isolates were collected from 43 patients over 3 months. Restriction endonuclease analysis (REA) of chromosomal DNA and repetitive-element polymerase chain reaction (rep-PCR) with primers based on repet...
Article
The macromolecular synthesis (MMS) operon consists of three genes: rpsU, which encodes the S21 ribosomal protein in Bacillus subtilis (Bs), rpsU is replaced by orfP23 which encodes a protein of unknown function), dnaG, encoding the DNA primase involved in the initiation of chromosome replication, and rpoD, which encodes the principal sigma subunit...
Article
Interspersed repetitive sequences in prokaryotic genomes can be used as oligonucleotide primer binding sites for polymerase chain reaction (PCR)-mediated genomic fingerprinting (rep-PCR). rep-PCR is based on the observation that outwardly facing oligonucleotide primers, complementary to interspersed repeated sequences, enable the amplification of d...
Article
Genotypic, or DNA-based, methods have become increasingly applicable for infectious disease diagnosis and epidemiologic analysis. The ability to assess the pathogen's genotype directly bypasses requirements for cultivation and may diminish diagnostic delays with fastidious organisms. Genotypic typing methods have enhanced epidemiologic studies by p...
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Repetitive element sequence-based polymerase chain reaction (rep-PCR) enables the generation of DNA fingerprints which discriminate bacterial species and strains. We describe the application of whole-cell methods which allow specimens from broth cultures or colonies from agar plates to be utilized directly in the PCR mixture. The rep-PCR-generated...
Article
A sample of 48 penicillin-resistant Streptococcus pneumoniae (PRSP) strains recovered between January 1989 and May 1991, primarily from infected children in Houston, was characterized by multilocus enzyme electrophoresis and repetitive extragenic palindromic-polymerase chain reaction genomic profiling. A heterogeneous array of 22 clonal genotypes w...
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Oligonucleotide probes which match consensus sequences of the repetitive extragenic palindromic (REP) element hybridize to genomic DNA of diverse bacterial species. Primers based on the REP sequence generate complex band patterns with genomic DNA in the polymerase chain reaction (PCR), a technique named REP-PCR. We used REP-PCR with genomic DNA to...
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We describe a novel method to map chromosomal Escherichia coli::Tn5 insertion mutations rapidly. This method utilizes the ends of Tn5 and the E. coli REP sequence as primer binding sites for the polymerase chain reaction (PCR). The unique E. coli chromosomal sequence located between these primer binding sites is amplified by PCR and used as a probe...