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Biomedical subjects

William H Wilson

Publications and source records attributed to William H Wilson.

At least 19 recordsLinked to original sources
PubMed2006

Molecular dynamics of Emiliania huxleyi and cooccurring viruses during two separate mesocosm studies.

In this study we used denaturing gradient gel electrophoresis, sequencing analysis, and analytical flow cytometry to monitor the dynamics and genetic richness of Emiliania huxleyi isolates and cooccurring viruses during two mesocosm experiments in a Norwegian fjord in 2000 and 2003. We exploited variations in a gene encoding a protein with calcium-binding motifs (GPA) and in the major capsid protein (MCP) gene to assess allelic and genotypic richness within E. huxleyi and E. huxleyi-specific viruses (EhVs), respectively. To our knowledge, this is the first report that shows the effectiveness of the GPA gene for analysis of natural communities of E. huxleyi. Our results revealed the existence of a genetically rich, yet stable E. huxleyi and EhV community in the fjordic environment. Incredibly, the same virus and host genotypes dominated in separate studies conducted 3 years apart. Both E. huxleyi-dominated blooms contained the same six E. huxleyi alleles. In addition, despite the presence of at least six and four EhV genotypes at the start of the blooms in 2000 and 2003, respectively, the same two virus genotypes dominated the naturally occurring infections during the exponential and termination phases of the blooms in both years.

Base Sequence↗
PubMed2006

Expression of a novel marine viral single-chain serine palmitoyltransferase and construction of yeast and mammalian single-chain chimera.

The genus Coccolithovirus is a recently discovered group of viruses that infect the globally important marine calcifying microalga Emiliania huxleyi. Surprisingly, the viral genome contains a cluster of putative sphingolipid biosynthetic genes not found in other viral genus. To address the role of these genes in viral pathogenesis, the ehv050 gene predicted to encode a serine palmitoyltransferase (SPT), the first and rate-limiting enzyme of sphingolipid biosynthesis, was expressed and characterized in Saccharomyces cerevisiae. We show that the encoded protein is indeed a fully functional, endoplasmic reticulum-localized, single-chain SPT. In eukaryotes SPT is a heterodimer comprised of long chain base 1 (LCB1) and LCB2 subunits. Sequence alignment and mutational analysis showed that the N-terminal domain of the viral protein most closely resembled the LCB2 subunit and the C-terminal domain most closely resembled the LCB1 subunit. Regardless of whether the viral protein was expressed as a single polypeptide or as two independent domains, it exhibited an unusual preference for myristoyl-CoA rather than palmitoyl-CoA. This preference was reflected by the increased presence of C16-sphingoid bases in yeast cells expressing the viral protein. The occurrence of a single-chain SPT suggested to us that it might be possible to create other fusion SPTs with unique properties. Remarkably, when the two subunits of the yeast SPT were thus expressed, the single-chain chimera was functional and displayed a novel substrate preference. This suggests that expression of other multisubunit membrane proteins as single-chain chimera could provide a powerful approach to the characterization of integral membrane proteins.

Amino Acid Sequence↗
PubMed2006

The coccolithovirus microarray: an array of uses.

The Coccolithoviridae is a recently discovered family of giant algal viruses. Here, we review the genomic and transcriptomic characterization of this family based on the results generated from a coccolithovirus microarray. The microarray has been used to aid the annotation of the genome, to investigate the infection process at the transcriptional level and to assess the diversity in genomic content within the family.

Genes, Viral↗
PubMed2006

Genome comparison of two Coccolithoviruses.

BACKGROUND: The Coccolithoviridae is a recently discovered family of viruses that infect the marine coccolithophorid Emiliania huxleyi. Following on from the sequencing of the type strain EhV-86, we have sequenced a second strain, EhV-163. RESULTS: We have sequenced approximately 80% of the EhV-163 genome, equating to more than 200 full length CDSs. Conserved and variable CDSs and a gene replacement have been identified in the EhV-86 and EhV-163 genomes. CONCLUSION: The sequencing of EhV-163 has provided a wealth of information which will aid the re-annotating of the EhV-86 genome and identified a gene insertion in EhV-163.

Base Sequence↗
PubMed2006

Annotation of environmental OMICS data: application to the transcriptomics domain.

Researchers working on environmentally relevant organisms, populations, and communities are increasingly turning to the application of OMICS technologies to answer fundamental questions about the natural world, how it changes over time, and how it is influenced by anthropogenic factors. In doing so, the need to capture meta-data that accurately describes the biological "source" material used in such experiments is growing in importance. Here, we provide an overview of the formation of the "Env" community of environmental OMICS researchers and its efforts at considering the meta-data capture needs of those working in environmental OMICS. Specifically, we discuss the development to date of the Env specification, an informal specification including descriptors related to geographic location, environment, organism relationship, and phenotype. We then describe its application to the description of environmental transcriptomic experiments and how we have used it to extend the Minimum Information About a Microarray Experiment (MIAME) data standard to create a domain-specific extension that we have termed MIAME/Env. Finally, we make an open call to the community for participation in the Env Community and its future activities.

Ecology↗
PubMed2006

Identification of a diagnostic marker to detect freshwater cyanophages of filamentous cyanobacteria.

Cyanophages are viruses that infect the cyanobacteria, globally important photosynthetic microorganisms. Cyanophages are considered significant components of microbial communities, playing major roles in influencing host community diversity and primary productivity, terminating cyanobacterial water blooms, and influencing biogeochemical cycles. Cyanophages are ubiquitous in both marine and freshwater systems; however, the majority of molecular research has been biased toward the study of marine cyanophages. In this study, a diagnostic probe was developed to detect freshwater cyanophages in natural waters. Oligonucleotide PCR-based primers were designed to specifically amplify the major capsid protein gene from previously characterized freshwater cyanomyoviruses that are infectious to the filamentous, nitrogen-fixing cyanobacterial genera Anabaena and Nostoc. The primers were also successful in yielding PCR products from mixed virus communities concentrated from water samples collected from freshwater lakes in the United Kingdom. The probes are thought to provide a useful tool for the investigation of cyanophage diversity in freshwater environments.

Anabaena↗
PubMed2006

Locus-specific gene expression pattern suggests a unique propagation strategy for a giant algal virus.

Emiliania huxleyi virus strain 86 is the largest algal virus sequenced to date and is unique among the Phycodnaviridae since its genome is predicted to contain six RNA polymerase subunit genes. We have used a virus microarray to profile the temporal transcription strategy of this unusual virus during infection. There are two distinct transcription phases to the infection process. The primary phase is dominated by a group of coding sequences (CDSs) expressed by 1 h postinfection that are localized to a subregion of the genome. The CDS of the primary group have no database homologues, and each is associated with a unique promoter element. The remainder of the CDSs are expressed in a secondary phase between 2 and 4 hours postinfection. Compartmentalized transcription of the two distinctive phases is discussed. We hypothesize that immediately after infection the nucleic acid of the virus targets the host nucleus, where primary-phase genes are transcribed by host RNA polymerase which recognizes the viral promoter. Secondary-phase transcription may then be conducted in the cytoplasm.

Cell Nucleus↗
PubMed2005

Evolutionary history of the Coccolithoviridae.

We recently determined the genome sequence of the Coccolithoviridae strain Emiliania huxleyi virus 86 (EhV-86), a giant double-stranded DNA (dsDNA) algal virus from the family Phycodnaviridae that infects the marine coccolithophorid E. huxleyi. Here, we determine the phylogenetic relationship between EhV-86 and other large dsDNA viruses. Twenty-five core genes common to nuclear-cytoplasmic large dsDNA virus genomes were identified in the EhV-86 genome; sequence from eight of these genes were used to create a phylogenetic tree in which EhV-86 was placed firmly with the two other members of the Phycodnaviridae. We have also identified a 100-kb region of the EhV-86 genome which appears to have transferred into this genome from an unknown source. Furthermore, the presence of six RNA polymerase subunits (unique among the Phycodnaviridae) suggests both a unique evolutionary history and a unique lifestyle for this intriguing virus.

Cluster Analysis↗
PubMed2005

Complete genome sequence and lytic phase transcription profile of a Coccolithovirus.

The genus Coccolithovirus is a recently discovered group of viruses that infect the globally important marine calcifying microalga Emiliania huxleyi. Among the 472 predicted genes of the 407,339-base pair genome are a variety of unexpected genes, most notably those involved in biosynthesis of ceramide, a sphingolipid known to induce apoptosis. Uniquely for algal viruses, it also contains six RNA polymerase subunits and a novel promoter, suggesting this virus encodes its own transcription machinery. Microarray transcriptomic analysis reveals that 65% of the predicted virus-encoded genes are expressed during lytic infection of E. huxleyi.

Apoptosis↗
PubMed2005

Validity and reliability of self-reported arthritis: Georgia senior centers, 2000-2001.

BACKGROUND: Arthritis and other rheumatic conditions are a common cause of disability among adults in the United States. Telephone interviews of the state-based Behavioral Risk Factor Surveillance System (BRFSS) are used by states and territories to estimate the prevalence of arthritis. The purpose of this study was to assess the validity and reliability of the 1996-2001 BRFSS arthritis case definition in a senior center population. METHODS: A total of 487 respondents at selected senior centers in Georgia were surveyed by telephone, evaluated 3 to 4 weeks later by board-certified rheumatologists, and completed a written survey in 2000 to 2001. Using the rheumatologists' summary assessment "Does this person have arthritis or a related condition" as the standard, the sensitivity and specificity of the BRFSS arthritis case definitions were calculated. Reliability for the BRFSS arthritis case definition was also calculated by comparing responses to the telephone survey with responses to a written survey. RESULTS: Sensitivity was 70.8% (95% confidence interval [CI]=65.9-75.6), and the specificity was 70.3% (95% CI=62.9-77.8). The agreement between the telephone and written responses indicating self-reported arthritis was high (kappa=0.68). Analyses were conducted in 2002 to 2004. CONCLUSIONS: Self-reported arthritis in the 1996-2001 BRFSS was highly reliable, and moderately sensitive and specific among these senior center participants.

Aged↗
PubMed2005

Maintenance therapy with fluoxetine in posttraumatic stress disorder: a placebo-controlled discontinuation study.

The effect of fluoxetine (FLU) in posttraumatic stress disorder was studied in a one-year trial. Subjects received open-label treatment for 6 months, followed by double-blind randomized treatment with FLU or placebo (PBO) for 6 months. Rates of relapse were compared using the Clinical Global Impressions of Improvement. One hundred twenty-three subjects entered open-label treatment, of whom 114 returned at least once. Sixty-two subjects were randomized to receive FLU or PBO, of whom 57 returned at least once and were analyzed. The dose of FLU ranged from 10 to 60 mg/d; at randomization, mean doses were 48.6 and 42.1 mg for FLU and PBO groups. Rates of relapse were 22% for FLU versus 50% for PBO (P = 0.02), and time to relapse on FLU was longer than for PBO (P = 0.02, log-rank statistic). The odds ratio for relapse on PBO relative to FLU was 3.50. No significant differences were found on other measures. Fluoxetine was well tolerated during double-blind treatment.

Adult↗
PubMed2005

Genetic diversity of marine Synechococcus and co-occurring cyanophage communities: evidence for viral control of phytoplankton.

Unicellular cyanobacteria of the genus Synechococcus are a major component of the picophytoplankton and make a substantial contribution to primary productivity in the oceans. Here we provide evidence that supports the hypothesis that virus infection can play an important role in determining the success of different Synechococcus genotypes and hence of seasonal succession. In a study of the oligotrophic Gulf of Aqaba, Red Sea, we show a succession of Synechococcus genotypes over an annual cycle. There were large changes in the genetic diversity of Synechococcus, as determined by restriction fragment length polymorphism analysis of a 403- bp rpoC1 gene fragment, which was reduced to one dominant genotype in July. The abundance of co-occurring cyanophage capable of infecting marine Synechococcus was determined by plaque assays and their genetic diversity was determined by denaturing gradient gel electrophoresis analysis of a 118-bp g20 gene fragment. The results indicate that both abundance and genetic diversity of cyanophage covaried with that of Synechococcus. Multivariate statistical analyses show a significant relationship between cyanophage assemblage structure and that of Synechococcus. These observations are consistent with cyanophage infection being a major controlling factor in picophytoplankton succession.

Bacteriophages↗
PubMed2005

The genome of S-PM2, a "photosynthetic" T4-type bacteriophage that infects marine Synechococcus strains.

Bacteriophage S-PM2 infects several strains of the abundant and ecologically important marine cyanobacterium Synechococcus. A large lytic phage with an isometric icosahedral head, S-PM2 has a contractile tail and by this criterion is classified as a myovirus (1). The linear, circularly permuted, 196,280-bp double-stranded DNA genome of S-PM2 contains 37.8% G+C residues. It encodes 239 open reading frames (ORFs) and 25 tRNAs. Of these ORFs, 19 appear to encode proteins associated with the cell envelope, including a putative S-layer-associated protein. Twenty additional S-PM2 ORFs have homologues in the genomes of their cyanobacterial hosts. There is a group I self-splicing intron within the gene encoding the D1 protein. A total of 40 ORFs, organized into discrete clusters, encode homologues of T4 proteins involved in virion morphogenesis, nucleotide metabolism, gene regulation, and DNA replication and repair. The S-PM2 genome encodes a few surprisingly large (e.g., 3,779 amino acids) ORFs of unknown function. Our analysis of the S-PM2 genome suggests that many of the unknown S-PM2 functions may be involved in the adaptation of the metabolism of the host cell to the requirements of phage infection. This hypothesis originates from the identification of multiple phage-mediated modifications of the host's photosynthetic apparatus that appear to be essential for maintaining energy production during the lytic cycle.

Bacteriophages↗
PubMed2004

A visual guide to expected blood levels of long-acting injectable risperidone in clinical practice.

OBJECTIVE: Risperidone is the only second-generation (atypical) antipsychotic medication available in a long-acting injectable formulation. The mechanism of drug delivery and the pharmacokinetics of this medication are distinctively different from the first-generation injectable depot medications. Antipsychotic blood levels have been reported in carefully managed single-dose and multiple-dose studies of long-acting risperidone. However, there have been no studies of blood levels produced by the variability in doses and schedules that may occur in clinical practice. Mathematical modeling allows for estimation of blood levels in a variety of clinical scenarios that have yet to be studied empirically. This paper presents mathematically modeled representations of antipsychotic blood levels in clinical situations with long-acting risperidone, with the goal of helping professionals, patients, and family members make informed decisions regarding treatment. METHODS: A model of single-dose pharmacokinetics was derived from a published, empirical single-dose study. The model was used to prepare graphs of expected multiple-dose schedules consistent with clinical situations, using empirically validated assumptions. RESULTS: The model was validated by comparison of the results of multiple-dose modeling with published empirical multi-dose data. Graphs of expected blood levels in several clinical situations are presented. Future empirical studies are required to fully validate these results. CONCLUSIONS: Mathematical models of antipsychotic blood levels in various common situations allow a better appreciation of the novel pharmacokinetics of long-acting injectable risperidone, which may lead to more informed decision-making.

Adolescent↗
PubMed2003

Reliabilities and intercorrelations of reported and objective measures of smoking in patients with schizophrenia.

We examined the test-retest reliabilities of reported and objective measures of smoking, and the intercorrelations among these measures, in acutely psychotic patients with schizophrenia to determine whether severe psychiatric illness affects the utility of these variables. All measures demonstrated good test-retest reliability. Objective measures of smoking were consistently intercorrelated and should be the preferred outcome measures in studies testing strategies to reduce smoking.

Adult↗
PubMed2003

Postural syncope after marijuana: a transcranial Doppler study of the hemodynamics.

Twenty-nine volunteers participated in a randomized, double-blind, placebo-controlled study. Cerebral blood velocity (CBV), pulse rate, blood pressure (BP), skin perfusion (SP) on forehead and plasma delta9 tetrahydrocannabinol (THC) levels were quantified during reclining and standing for 10 min before and after THC infusions and marijuana smoking. Both THC and marijuana induced postural dizziness, with 28% reporting severe symptoms. Intoxication and dizziness peaked immediately after drug. The severe dizziness group showed the most marked postural drop in CBV and BP and showed a drop in pulse rate after an initial increase during standing. Postural dizziness was unrelated to plasma levels of THC and other indices.

Adult↗
PubMed2003

Virus succession observed during an Emiliania huxleyi bloom.

Denaturing gradient gel electrophoresis was used as a molecular tool to determine the diversity and to monitor population dynamics of viruses that infect the globally important coccolithophorid Emiliania huxleyi. We exploited variations in the major capsid protein gene from E. huxleyi-specific viruses to monitor their genetic diversity during an E. huxleyi bloom in a mesocosm experiment off western Norway. We reveal that, despite the presence of several virus genotypes at the start of an E. huxleyi bloom, only a few virus genotypes eventually go on to kill the bloom.

Base Sequence↗