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M Wilson

Publications and source records attributed to M Wilson.

At least 199 records · Page 11Linked to original sources
PubMed1999

Exploring drug-induced alterations in gene expression in Mycobacterium tuberculosis by microarray hybridization.

Tuberculosis is a chronic infectious disease that is transmitted by cough-propelled droplets that carry the etiologic bacterium, Mycobacterium tuberculosis. Although currently available drugs kill most isolates of M. tuberculosis, strains resistant to each of these have emerged, and multiply resistant strains are increasingly widespread. The growing problem of drug resistance combined with a global incidence of seven million new cases per year underscore the urgent need for new antituberculosis therapies. The recent publication of the complete sequence of the M. tuberculosis genome has made possible, for the first time, a comprehensive genomic approach to the biology of this organism and to the drug discovery process. We used a DNA microarray containing 97% of the ORFs predicted from this sequence to monitor changes in M. tuberculosis gene expression in response to the antituberculous drug isoniazid. Here we show that isoniazid induced several genes that encode proteins physiologically relevant to the drug's mode of action, including an operonic cluster of five genes encoding type II fatty acid synthase enzymes and fbpC, which encodes trehalose dimycolyl transferase. Other genes, not apparently within directly affected biosynthetic pathways, also were induced. These genes, efpA, fadE23, fadE24, and ahpC, likely mediate processes that are linked to the toxic consequences of the drug. Insights gained from this approach may define new drug targets and suggest new methods for identifying compounds that inhibit those targets.

Antitubercular Agents↗
PubMed1999

Patient with a 22q11.2 deletion with no overlap of the minimal DiGeorge syndrome critical region (MDGCR).

The apparent lack of genotype/phenotype correlation in patients with the DiGeorge anomaly and velocardiofacial syndrome (DGA/VCFS; the "22q11 deletion syndrome") indicates a complex genetic condition. Most cases, whatever the phenotype, have a 1.5-3 Mb chromosomal deletion that includes the minimal DiGeorge critical region (MDGCR). Another potential critical region on 22q11 has been suggested based on two patients with distal deletions outside the MDGCR. We report on a patient with a VCFS phenotype who has a deletion, mapped by short tandem repeat polymorphic loci and fluorescence in situ hybridization analysis, distal to and not overlapping the MDGCR. This patient is deleted for several genes, including the T-box 1 gene (TBX1; a transcription regulator expressed early in embryogenesis) and catechol-O-methyltransferase (COMT; involved in neurotransmitter metabolism). We discuss the role these two genes may play in the clinical phenotype of the patient.

Adult↗
PubMed1999

The use of chloromethyl-X-rosamine (Mitotracker red) to measure loss of mitochondrial membrane potential in apoptotic cells is incompatible with cell fixation.

BACKGROUND: A recent report by Macho et al. (Cytometry 25: 333-340, 1996) described the use of chloromethyl-X-rosamine (CMX-Ros) as a fixable probe for detection of loss of mitochondrial membrane potential (psi(mit)), an early event in many models of apoptosis. However, this previous report lacked a description of any direct comparisons between pre- and post-fixation analyses of normal and apoptotic cells stained with CMX-Ros. METHODS: Using a variety of cell types, we investigated the effect of paraformaldehyde fixation on cellular retention of CMX-Ros and the implications of this for the subsequent analysis of changes in psi(mit) in cells undergoing apoptosis. RESULTS: We found that following fixation, the resolution between normal cells with polarized mitochondria and apoptotic cells with depolarized mitochondria is reduced to the extent that accurate discrimination between the cell types is no longer possible. CONCLUSIONS: Overall, our results are consistent with CMX-Ros being a valid probe for psi(mit) in intact cells but only when the cells are stained and analyzed immediately. Thus, our results suggest that the proposed applications for CMX-Ros in multiple parameter analysis of fixed cells are inappropriate and will lead to spurious results.

Apoptosis↗
PubMed1999

Transfer of a conjugative transposon, Tn5397 in a model oral biofilm.

A tetracycline resistance profile was established from a microcosm dental plaque in a constant depth film fermenter. The fermenter was inoculated with a Bacillus subtilis strain which contained the conjugative transposon, Tn5397, which confers tetracycline resistance upon its host. After 6 hour and 24 hour the tetracycline resistance profile of the biofilm was redetermined and a tetracycline resistant Streptococcus species was isolated. A molecular analysis of this strain confirmed that Tn5397 was present in the genomic DNA of the isolate. These data represent the first report, to our knowledge, of intergeneric transfer of a conjugative transposon in a mixed species biofilm and demonstrates the ability of conjugative transposons to disseminate antibiotic resistance genes in a mixed species environment.

Bacillus subtilis↗
PubMed1999

Structure-activity analysis of the effects of lysophosphatidic acid on platelet aggregation.

Lysophosphatidic acid (1-acyl-sn-glycero-3-phosphate or LPA) is a phospholipid mediator displaying numerous and widespread biological activities and thought to act via G-protein-coupled receptors. Here we have studied the effects on human platelets of a number of LPA analogues, including two enantiomers of both N-palmitoyl-(L)-serine-3-phosphate ((L) and (D)NAPS for N-acyl-phosphoserine) and 2-(R)-N-palmitoyl-norleucinol-1-phosphate ((R) and (S)PNPA), cyclic analogues of 1-acyl-sn-glycero-3-phosphate (cPA) and of 1-O-hexadecyl-sn-glycero-3-phosphate (cAGP), sphingosine-1-phosphate (SPP), as well as two palmitoyl derivatives of dioxazaphosphocanes bearing either a P-H or a P-OH bond (DOXP-H and DOXP-OH, respectively). Nine of these compounds induced platelet aggregation with the following order of potency: SPP < cAGP < DOXP-OH < (L)NAPS = (D)NAPS < (R)PNPA = (S)PNPA < LPA < AGP, EC50 varying between 9.8 nM and 8.3 microM. Two of these compounds (SPP and cAGP) appeared as weak agonists inducing platelet aggregation to only 33% and 41%, respectively, of the maximal response attained with LPA and other analogues. In cross-desensitization experiments, all of these compounds specifically inhibited LPA-induced aggregation, suggesting that they were all acting on the same receptor(s). In contrast, cPA and DOXP-H did not trigger platelet aggregation but instead specifically inhibited the effects of LPA in a concentration-dependent manner. The inhibitory action of cPA did not vary with the acyl chain length or the presence of a double bond and did not involve an increase in cAMP. These data thus confirm the lack of stereospecificity of platelet LPA receptor(s). In addition, since the order of potency of some analogues is different from that described in other cells, our results suggest that platelets contain (a) pharmacologically distinct receptor(s) whose molecular identity still remains to be established. Finally, this unique series of compounds might be used for further characterization of other endogenous or recombinant LPA receptors.

Humans↗
PubMed1999

Differences in uniquantal amplitude between sites reduce uniquantal variance when few release sites are active.

In many types of central neurons, the coefficient of variation (CV) of stimulus-evoked uniquantal events inferred from quantal analysis is small, frequently less than 20%. In contrast, spontaneous putative uniquantal events (minis) from the same neurons are much more variable in amplitude, having a CV of roughly 50% or more. One explanation for this discrepancy is that, if the variance in mini amplitude were generated by differences between release sites, the small number of sites activated during stimulation would sometimes fortuitously have similar quantal amplitudes. Only in these fortuitous cases where uniquantal variance is small could quantal peaks be resolved, and therefore the uniquantal CV seen in the subset of cells where quantal analysis can be performed would systematically be much smaller than predicted by the mini distribution. We have explored this possibility by Monte Carlo simulation assuming all variance in mini amplitude to be due to intersite differences in uniquantal amplitude. We find that when a small number of release sites are activated under these conditions, there is a reduction in the expected uniquantal variance. However, the expected uniquantal CV is highly variable from one experiment to the next, and low uniquantal CVs are not expected to be seen often enough to account for the high frequency with which quantal peaks with a uniquantal CV < 20% are observed experimentally. We conclude that variance in mini amplitude between release sites cannot account for the small uniquantal CV seen in quantal analysis of many central synapses.

Hippocampus↗
PubMed1999

The neuron-specific K-Cl cotransporter, KCC2. Antibody development and initial characterization of the protein.

The neuron-specific K-Cl cotransporter (KCC2) is hypothesized to function as an active Cl- extrusion pathway important in postsynaptic inhibition mediated by ligand-gated anion channels, like gamma-aminobutyric acid type A (GABAA) and glycine receptors. To understand better the functional role of KCC2 in the nervous system, we developed polyclonal antibodies to a KCC2 fusion protein and used these antibodies to characterize and localize KCC2 in the rat cerebellum. The antibodies specifically recognized the KCC2 protein which is an approximately 140-kDa glycoprotein detectable only within the central nervous system. The KCC2 protein displayed a robust and punctate distribution in primary cultured retinal amacrine cells known to form exclusively GABAAergic synapses in culture. In immunolocalization studies, KCC2 was absent from axons and glia but was highly expressed at neuronal somata and dendrites, indicating a specific postsynaptic distribution of the protein. In the granule cell layer, KCC2 exhibited a distinct colocalization with the beta2/beta3-subunits of the GABAA receptor at the plasma membrane of granule cell somata and at cerebellar glomeruli. KCC2 lightly labeled the plasma membrane of Purkinje cell somata. Within the molecular layer, KCC2 exhibited a distinctly punctate distribution along dendrites, indicating it may be highly localized at inhibitory synapses along these processes. The distinct postsynaptic localization of KCC2 and its colocalization with GABAA receptor in the cerebellum are consistent with the putative role of KCC2 in neuronal Cl- extrusion and postsynaptic inhibition.

Animals↗
PubMed1999

Germline mutations in the extracellular domains of the 55 kDa TNF receptor, TNFR1, define a family of dominantly inherited autoinflammatory syndromes.

Autosomal dominant periodic fever syndromes are characterized by unexplained episodes of fever and severe localized inflammation. In seven affected families, we found six different missense mutations of the 55 kDa tumor necrosis factor receptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds. Soluble plasma TNFR1 levels in patients were approximately half normal. Leukocytes bearing a C52F mutation showed increased membrane TNFR1 and reduced receptor cleavage following stimulation. We propose that the autoinflammatory phenotype results from impaired downregulation of membrane TNFR1 and diminished shedding of potentially antagonistic soluble receptor. TNFR1-associated periodic syndromes (TRAPS) establish an important class of mutations in TNF receptors. Detailed analysis of one such mutation suggests impaired cytokine receptor clearance as a novel mechanism of disease.

Amino Acid Sequence↗
PubMed1999

Discourse deficits following right hemisphere damage in deaf signers.

Previous findings have demonstrated that hemispheric organization in deaf users of American Sign Language (ASL) parallels that of the hearing population, with the left hemisphere showing dominance for grammatical linguistic functions and the right hemisphere showing specialization for non-linguistic spatial functions. The present study addresses two further questions: first, do extra-grammatical discourse functions in deaf signers show the same right-hemisphere dominance observed for discourse functions in hearing subjects; and second, do discourse functions in ASL that employ spatial relations depend upon more general intact spatial cognitive abilities? We report findings from two right-hemisphere damaged deaf signers, both of whom show disruption of discourse functions in absence of any disruption of grammatical functions. The exact nature of the disruption differs for the two subjects, however. Subject AR shows difficulty in maintaining topical coherence, while SJ shows difficulty in employing spatial discourse devices. Further, the two subjects are equally impaired on non-linguistic spatial tasks, indicating that spared spatial discourse functions can occur even when more general spatial cognition is disrupted. We conclude that, as in the hearing population, discourse functions involve the right hemisphere; that distinct discourse functions can be dissociated from one another in ASL; and that brain organization for linguistic spatial devices is driven by its functional role in language processing, rather than by its surface, spatial characteristics.

Aged↗
PubMed1999

A critical evaluation of enzyme immunoassays for detection of antinuclear autoantibodies of defined specificities. I. Precision, sensitivity, and specificity.

OBJECTIVE: To determine the performance characteristics of enzyme-based immunoassay (EIA) kits for the detection of antinuclear and other autoantibodies of defined specificities. METHODS: Nine manufacturers of EIA kits to detect antibodies of defined specificities participated in a study in which they received coded sera from the Centers for Disease Control and Prevention. These coded sera contained different dilutions of antibody of one specificity mixed with sera containing antibodies of other specificities. The manufacturers were asked to use their standard technology to determine antibody content and send the data to a committee of the International Union of Immunological Societies for analysis. The data were analyzed for sensitivity and specificity in the detection of anti-double-stranded DNA (anti-dsDNA), anti-single-stranded DNA, antihistone, anti-Sm, anti-U1 RNP, anti-SSA/Ro, anti-SSB/La, anti-Scl-70 (DNA topoisomerase I), anticentromere, and anti-Jo-1 antibodies. In addition, replicate samples were included in the coded sera to evaluate the precision of each EIA method. RESULTS: Lack of sensitivity and specificity was most evident in the anti-dsDNA and anti-Sm kits, although 2 kits for anti-dsDNA achieved acceptable sensitivity and specificity. Generally, anti-SSA/Ro, anti-SSB/La, anti-Scl-70, anticentromere, and anti-Jo-1 kits performed well. Many false-positive results were obtained with a multiple myeloma serum containing cryoprecipitates, but multiple myeloma sera without cryoprecipitates presented no problem in the EIA system. Precision, based on evaluation of replicate samples, varied from very good to poor. CONCLUSION: No single manufacturer was clearly superior to others in terms of their products' overall sensitivity, specificity, and precision. Areas that needed improvement were in kits for the detection of antibodies to dsDNA and to Sm antigen. Some EIA kits achieved good sensitivity and specificity. Individual manufacturers were informed of the performance of their respective kits so they could take measures to correct perceived deficiencies and thus improve the reliability of a group of important diagnostic assays used in the evaluation of systemic rheumatic diseases.

Antibodies, Antinuclear↗
PubMed1999

Organization of the genes encoding the human proteasome activators PA28alpha and beta.

Two proteasome activators PA28alpha and beta, which have been implicated in antigen processing for loading class I MHC molecules, are synthesized in response to Ifn-gamma. The human genes encoding these activators (PSME1 and PSME2, respectively) were analyzed by sequencing. Each gene comprised 11 exons, consistent with gene duplication during vertebrate evolution. The intron/exon organization of both genes was highly conserved, the major difference being the absence of the exon encoding the lysine and glutamic acid-rich 'KEKE' motif in PA28beta. Two other genes of relevance to the immune system were located close to those for PA28 at 14q11.2 including ISGF3G, a protein involved in transcription after IFNalpha signalling. These sequences were also characterized.

Amino Acid Sequence↗
PubMed1999

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Journal Article↗
PubMed1999

Exposure to violence and posttraumatic stress symptomatology among abortion clinic workers.

The intent of this study was to examine the relationship between exposure to abortion clinic violence, either as a victim or witness, and the reporting of posttraumatic stress disorder (PTSD) symptoms among clinic employees. Semi-structured interviews with 71 clinic workers from eight abortion clinics in a Southeastern state were used for analyses. Findings showed that as victims, clinic workers experienced moderate forms of violence and witnessed greater variety and numbers of violent acts. Twenty-one percent of the sampled workers reported symptoms similar to the syndrome described in the DSM-IIIR/DSM-IV classification for PTSD. A multivariate analysis showed that even when controlling for significant life circumstances and stressors outside the clinic setting, witnessing violence was a significant predictor of PTSD symptomatology.

Abortion, Induced↗
PubMed1999

Relationship of amniotic fluid markers of intra-amniotic infection with histopathology in cases of preterm labor with intact membranes.

OBJECTIVE: To evaluate the correlation of amniotic fluid (AF) markers (AFMs) of intra-amniotic infection with histopathologic findings in cases of preterm labor with intact membranes, between 22 and 36 weeks' gestation. STUDY DESIGN: We reviewed the charts of patients admitted in preterm labor with intact membranes between January 1993 and December 1996. Those having amniocentesis were identified, and AFMs were compared with histopathology in patients who delivered within 48 hours of the amniocentesis. The AFMs evaluated were glucose, polymorphonuclear leukocytes, Gram stain, and culture. All placentae were reviewed by a single pathologist blinded to the AF findings. Histologic evidence of acute inflammation was defined by findings of both subchorial intervillositis and marginating choriodeciduitis. The sensitivities, specificities, and positive and negative predictive values of the various AFMs were calculated. RESULTS: Of 556 women with intact membranes presenting in preterm labor, 181 (32.6%) had amniocentesis and 88 delivered within 48 hours of the amniocentesis. Histopathologic chorioamnionitis was seen in 53 patients (60.2%). The findings (with their sensitivity, specificity, and positive and negative predictive values) were: polymorphonuclear leukocytes at > 10/high-power field (22.6%, 97.2%, 92.3%, and 46.1%), positive Gram stain (26.4%, 94.6%, 87.5%, and 47.3%), culture (28.3%, 92.1%, 83.3%, and 47.9%), and glucose of < 15 mg/dl (28.3%, 94.6%, 88.2%, and 47.9%), respectively. Using a receiver-operator characteristic curve for different level of AF glucose, a glucose level of < 20 mg/dl was the most sensitive AF predictor of histologic chorioamnionitis. CONCLUSION: Histopathologic evidence of chorioamnionitis was present in 60.2% of cases of preterm births due to preterm labor in women who at our institution were offered and accepted amniocentesis and subsequently delivered within 48 hours. AFMs may be useful predictors of histologic chorioamnionitis. The most efficient AFM for chorioamnionitis in this group of patients was glucose at < 20 mg/dl.

Adult↗
PubMed1999

Registered nurses' descriptions of their health assessment practices.

The delivery of health-care services in Australia is undergoing many changes. The move towards home-based acute care has precipitated a review of many nursing care practices. An important consequence of these changes is the need for registered nurses to be adequately equipped to conduct systematic health assessments. This descriptive study used a questionnaire designed to elicit short-answer responses in order to investigate how registered nurses described their health assessment practices and what type of data they collected. The findings indicate that respondents possess divergent conceptualizations of health assessment, and that they predominately use health assessment data to support medical therapies. Discussion focuses on the implications of these findings for nursing practice.

Attitude of Health Personnel↗