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Biomedical subjects

V Williams

Publications and source records attributed to V Williams.

At least 19 recordsLinked to original sources
PubMed1992

Variation in the composition of the venom from a single specimen of Pseudonaja textilis (common brown snake) over one year.

Venom was collected over a 12-month period from a single specimen of Pseudonaja textilis. No trends in the weight of venom extracted or protein content were noted. Amidolytic activity, coagulant and esterolytic activity showed a decrease over the summer months, while a rise in phosphodiesterase and 5' nucleotidase activity was noted at this time. Precipitin lines developed against the venoms by brown snake antivenom showed variability over the 12-month period. Gel filtration and SDS-polyacrylamide gel electrophoresis profiles showed quantitative and minor qualitative differences; however, the variation noted in the activities of these venoms was not predictable from these profiles.

Animals↗
PubMed1991

Snake venom variability: methods of study, results and interpretation.

The causes and implications of venom variability are discussed with a review of the literature. Venom variability may have an impact on both primary venom research and management of snakebite, including selection of antivenoms and selection of specimens for antivenom production. Choice of venom is reviewed, including venom collection, maintenance, and pooled venom versus venom milked from individual specimens, the latter being more reliable in many applications. Intraspecific variability resulting in clinical variability of envenomation occurs and is reviewed. Venom variability is considered at several levels; interfamily, intergenus, interspecies, intersubspecies and intraspecies, geographical variation, between individual specimens, and in individual specimens, due to seasonal variation, diet, habitat, age-dependent change, and sexual dimorphism. It is concluded that venom researchers must be aware of venom variability both in selecting their sources of venom and in interpretation of results. Producers of antivenom must utilize an understanding of such variability in selecting sources of venom for antivenom production to ensure representation of all venom types required within each antivenom. Furthermore, clinicians treating snakebite should understand the influence of venom variability on both the presentation of envenomation and the treatment implications.

Animals↗
PubMed1991

Efficacy of behavioral versus triazolam treatment in persistent sleep-onset insomnia.

OBJECTIVE: This study compared differential effects of behavioral therapy and triazolam in a clinical population with sleep-onset insomnia. Triazolam was hypothesized to decrease sleep latency and frequency and duration of awakening, with some effects during the first night's administration. But at follow-up, sleep measures were predicted to return to baseline levels. Behavioral treatment was hypothesized to effect sleep after 2 or more weeks of training which persisted at follow-up. METHOD: Thirty patients with average sleep latencies of 81.48 minutes, who reported chronic insomnia for an average of 2.6 years, were randomly assigned to one of two treatment groups: behavioral stimulus control/relaxation training and triazolam. RESULTS: Both treatments decreased sleep latency but differentially. Triazolam was effective immediately but maintained only some gains at follow-up. Behavioral treatment decreased sleep latency beginning the second week, when subjects expected no improvement, with gains maintained at follow-up. Comparisons showed that triazolam group latencies returned toward baseline, while behavioral group gains were maintained at follow-up. CONCLUSIONS: Triazolam treatment showed superior immediate treatment effects, while behavioral treatment showed superior treatment effects at follow-up, effects that accrued during the training period and differentially persisted at follow-up. One treatment strategy implied by these results would be to combine these two interventions concurrently. This would seem to use the immediate effects produced by the medication until the behavioral skills were learned, at which point medication would be terminated. This strategy could offer immediate relief and sustained effects at drug termination.

Adult↗
PubMed1990

Variation in venom composition and reactivity in two specimens of yellow-faced whip snake (Demansia psammophis) from the same geographical area.

Gel filtration chromatography and SDS-PAGE of venom from two specimens of Demansia psammophis showed little similarity. Amidolytic activity of the venoms, however, was in the same order of reactivity against various chromogenic substrates. The venom from both snakes produced precipitin lines with brown snake antivenom but the venom detection kit (Commonwealth Serum Laboratories) identified one venom as brown snake (Pseudonaja sp.) and the other as tiger snake (Notechis sp.). These results raise questions about the phylogeny of this species.

Animals↗
PubMed1989

Purification and properties of a procoagulant from peninsula tiger snake (Notechis ater niger) venom.

The procoagulant from Notechis ater niger was purified by gel filtration and anion exchange chromatography. It is a protein with an approximate mol.wt of 58,000 and in the presence of B mercaptoethanol is reduced to two chains with mol.wts of 37,000 and 23,000. The procoagulant has a pI of 7.3. The whole venom requires factor V to be present to bring about coagulation while Ca2+ and phospholipid are not essential, but when present stimulate this process. Normal prothrombin, but not decarboxyprothrombin, is converted by the venom. The activity of the procoagulant from Notechis species has been equated with factor Xa and in this study the similarity is noted, while ecarin-like characteristics in not requiring Ca2+ and phospholipid and an ability to clot heparinised plasma were also noted.

Anticoagulants↗
PubMed1989

Clinical evaluation of a benzofuroquinolizine alpha 2-adrenoceptor antagonist.

The pharmacodynamics of MK-912, a benzofuroquinolizine alpha-adrenoceptor antagonist, were evaluated in healthy male volunteers. Eight subjects were treated with single oral doses of 0.1, 1.0, and 2.0 mg MK-912 and with a placebo in a four-period, double-blind, balanced, crossover study. Hemodynamic effects were observed with the 2.0 mg dose of MK-912 (peak increase from baseline in systolic and diastolic blood pressure +/- SEM, 14.8/9.2 +/- 2.9/2.1 mm Hg; peak increase in heart rate, 6.3 +/- 2.1 beats/min; p less than 0.05 versus placebo). Plasma concentrations of 3-methoxy-4-hydroxyphenylglycol (MHPG, a catecholamine metabolite) were increased 29% +/- 7% and 40% +/- 10% above baseline 2 hours after administration of 1.0 and 2.0 mg MK-912, respectively (p less than 0.01 compared with placebo). A modest dose-dependent reduction (5% to 10%) in fasting plasma glucose concentration was observed 1/2 to 1 hour after administration of 1.0 and 2.0 mg MK-912 (p less than 0.05 compared with placebo), without significant change in plasma insulin values. MK-912 was well tolerated, although it did have a mild anxiogenic effect. MK-912 is a potent, orally active agent with a pharmacologic profile consistent with alpha 2-adrenoceptor antagonism.

Adrenergic alpha-Antagonists↗
PubMed1989

Severe envenomation with convulsion following multiple bites by a common brown snake, Pseudonaja textilis.

A case report of envenomation by a common brown snake, Pseudonaja textilis, in a 3.3 year old boy is presented. He suffered a brief grand mal convulsion 10 min after the bite which was shortly after removal of a compression bandage. A severe coagulopathy of the defibrination type required administration of five ampoules of brown snake monovalent antivenom (CSL). The association of envenomation by snakes and convulsions is discussed, as is the management of severe defibrination due to envenomation.

Animals↗
PubMed1989

Development and characterization of a monoclonal antibody against the tube precipitin antigen of Coccidioides immitis.

Primary infection with Coccidioides immitis is commonly accompanied by the production of an immunoglobulin M precipitin antibody which is detected by the tube precipitin (TP) assay or by the immunodiffusion assay for TP antibody (IDTP assay). In the present investigation, spleen cells from spherulin-immunized BALB/c mice were fused with SP2/O Ag14 myeloma cells, and the resulting hybridomas were screened for antibody to the IDTP antigen by using an enzyme-linked immunosorbent assay. Positive hybridomas were cloned by limiting dilution and injected into pristane-primed mice for ascites production. Characterization of antibody reactivity was accomplished with the IDTP assay, two-dimensional immunoelectrophoresis, and immunoblotting. An immunoglobulin G1 monoclonal antibody which reacts with the IDTP antigen of C. immitis is described. The epitope that is recognized by the monoclonal antibody is also present, but to a lesser extent, on a second coccidioidal antigen which has been designated antigen 2. The monoclonal antibody was not reactive in immunoblots of histoplasmin or blastomycin, indicating that the epitope recognized by this antibody may be specific for C. immitis.

Animals↗
PubMed1988

Variation in venom proteins from isolated populations of tiger snakes (Notechis ater niger, N. scutatus) in South Australia.

Pooled venom of peninsula tiger snakes (Notechis ater niger) from 11 insular populations and one mainland area, and from a single population of the mainland tiger snake (N. scutatus) were subjected to SDS-PAGE and gel filtration chromatography. At least 20 proteins were resolved in the SDS-PAGE, some of which were common to all populations, but many others were highly variable. Elution profiles produced through gel filtration showed a clustering of some populations with like profiles, while others had distinctive patterns. Similarities and dissimilarities between each population venom profile were appraised. Variation in the venom patterns was independent of prey type or local ecology. Statistical analysis of the SDS-PAGE banding patterns suggests that grouping of populations was dependent on their relative geographic position and the time of isolation of each population from one another and the mainland population.

Animals↗
PubMed1987

Variation in venom constituents within a single isolated population of peninsula tiger snake (Notechis ater niger).

Venom from seven individuals in a homogeneous isolated population of Notechis ater niger on Roxby Island, off the South Australia coast, was subjected to gel filtration liquid chromatography and polyacrylamide gel electrophoresis to determine the extent of homogeneity of the venom constituent profile. The gel filtration chromatograms from six of the specimens were easily equated, while the seventh showed a slight variation. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of the venoms in a native and reduced state showed no detectable difference between six of the seven individuals, the remaining individual showing minor changes only in the native venom.

Chromatography, Gel↗
PubMed1987

Swivel walkers in Duchenne muscular dystrophy.

Swivel walkers were used to provide low energy ambulation in 11 boys with Duchenne muscular dystrophy in schools for the physically handicapped in South Glamorgan. Our preliminary experience suggests that these walkers improve the quality of life and provide a useful part of the physical treatment of the condition.

Adolescent↗
PubMed1987

The effect of halothane general anaesthesia on platelet function.

Major craniofacial surgery has the potential for very large blood loss, frequently greater than one blood volume. In order that an assessment could be made of any deficiencies of platelet function or coagulation, tests were performed at intervals during the operation. None of the coagulation parameters showed variation below normal limits during the operation, but in vitro platelet aggregation showed significant decreases to several agonists.

Adolescent↗
PubMed1987

Localization of chlorotetracycline fluorescence in human polymorphonuclear neutrophils.

Chlorotetracycline (CTC) has been used in many cells as a probe for membranous calcium. In polymorphonuclear neutrophils (PMN), the changes in CTC fluorescence upon stimulation are considered to monitor an early event in the activation process. Using quantitative video-enhanced microscopy, we report that in resting cells about 80% of the CTC signal emanates from the perinuclear region of the cell, indicating that internal structures are labeled with CTC. Approximately 20% of the total CTC fluorescence is taken up in a compartment sensitive to mitochondrial inhibitors, which is not present in neutrophils depleted of nucleus and granules or cytoplasts. Upon stimulation PMN loaded with CTC exhibit a rapid, biphasic decrease in fluorescence that is dose dependent. The second phase of the response is not seen in neutrophil cytoplasts. These results suggest that internal stores of CTC are responsive upon stimulation and could account for the later decrease in CTC fluorescence, whereas the early phase of CTC changes represents the plasma membrane response.

Calcium↗