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Biomedical subjects

V Williams

Publications and source records attributed to V Williams.

At least 37 records · Page 2Linked to original sources
PubMed1995

Accuracy of interpretation of cranial computed tomography scans in an emergency medicine residency program.

STUDY OBJECTIVES: To determine the concordance of emergency physicians and radiologists in interpreting cranial computed tomography (CT) scans. The study also sought to determine the clinical significance of misinterpretations of cranial CT scans by emergency physicians. DESIGN: Prospective cohort study. SETTING: A county hospital emergency medicine residency program. PARTICIPANTS: Five hundred fifty-five patients undergoing CT scanning during emergency department evaluation. RESULTS: Forty-nine percent (272) of the indications for CT scanning were for trauma, 14.2% (79) were for cerebrovascular accident, 25.1% (139) were for headache, 15.1% (84) were for seizure, and 13.7% (76) were for miscellaneous reasons. The radiologists interpreted 46.1% (256) of the CT scans as abnormal. The most frequent abnormalities were scalp hematoma, 15.2% (39); infarction, 14.1% (36); calcification, 6.3% (16); contusion, 6.3% (16); parenchymal hemorrhage, 5.1% (13); and mass, 5.1% (13). Nonconcordance between radiologists and emergency physicians was found in 38.7% (206) of the cases. Potentially clinically significant misinterpretations were found in 24.1% (131) of the total sample. These misinterpretations included 62 missed major findings (11.4% of total sample): 25 new infarcts, 10 mass lesions, 8 cases of cerebral edema, 8 parenchymal hemorrhages, 5 contusions, 4 subarachnoid hemorrhages, 1 epidural hematoma, and 1 subdural hematoma. However, on chart review, only three patients (0.6%) were found to have been managed inappropriately, and none had an adverse outcome. CONCLUSION: The misinterpretation rate of cranial CT scans by emergency physicians is of potential clinical concern. However, clinical mismanagement is rare. We recommend that more formal education in CT interpretation be included in residency training and continuing medical education programs for emergency physicians.

Brain Diseases↗
PubMed1995

Biochemical markers of cerebral injury in patients with minor head trauma and ethanol intoxication.

OBJECTIVE: To determine whether biochemical markers can selectively identify those intoxicated patients with presumed minor head injuries who are likely to have CT evidence of intracranial injury. METHODS: Patients presenting to the ED with simultaneous presumed minor head trauma and ethanol intoxication were prospectively entered into this cross-sectional study. Following phlebotomy, all patients received cranial CT. Associations between the presence of an abnormal CT scan for injury and serum levels of the following biochemical markers were sought: serum catecholamines, creatine kinase-brain band (CK-BB), and serum amylase. Serum levels are reported as mean +/- SEM. RESULTS: Nine of the 107 patients (8.4%; 95% CI 3.9-15.4%) had evidence of intracranial injury on CT. Mean serum CK-BB (16.1 +/- 3.7 vs 13.2 +/- 9.6 ng/mL), serum norepinephrine (913 +/- 117 vs 1,089 +/- 76 pg/mL), and serum amylase (64.9 +/- 14.8 vs 84 +/- 4.7 U/L) levels were not significantly different in patients with and without CT evidence of intracranial injury, respectively. Mean serum epinephrine (298 +/- 54 vs 167 +/- 18 pg/mL; p = 0.03) and serum dopamine (218 +/- 50 vs 130 +/- 9 pg/mL; p = 0.014) levels were significantly elevated in the group with intracranial injury on CT. A threshold level of serum dopamine > or = 140 pg/mL yields a sensitivity of 89% (95% CI 52-100%) and a specificity of 80% (95% CI 70-87%) for CT-evident injury. A threshold level of serum epinephrine > or = 218 pg/mL yields a sensitivity of 89% (95% CI 52-100%) and a specificity of 80% (95% CI 70-87%) for CT-evident injury. CONCLUSION: Elevated serum epinephrine and dopamine levels are associated with intracranial CT-evident injury for ethanol-intoxicated patients with presumed minor head injuries. The potential use of these biochemical markers to guide a more selective approach to cranial CT scanning warrants further evaluation.

Alcoholic Intoxication↗
PubMed1994

Comparative study on the procoagulant from the venom of Australian brown snakes (Elapidae; Pseudonaja spp.).

The procoagulant was isolated from the venom of four clinically significant species of brown snake; Pseudonaja affinis, P. inframacula, P. nuchalis, and P. textilis. HPLC elution profiles and PAGE showed a high degree of homology between the procoagulants from the four species. Antiserum from the CSL Ltd (Brown Snake Antivenom) produced a single band against all four procoagulants. The specific activity of the procoagulant varied between species, while inhibitory studies indicated that the procoagulants were serine proteases with a sialic acid component which also contributes to the coagulant action.

Animals↗
PubMed1993

Neurosurgical intensive care unit organization and function: an American experience.

This article describes the organization and function of a university-based neurosurgical intensive care unit. The unit's success has been based in part on its physical structure and in larger part on its organization. Patients are comanaged by a team of neurosurgeons and anesthesiologist intensive care specialists, who receive twice-weekly input from all other participating patient care specialists, including nurses, physical therapists, social workers, and others. This type of approach promotes teamwork and fosters mutual respect among the team. It also improves patient care and, frequently, outcome.

Critical Care↗
PubMed1993

Comparison of CNS adverse effects between astemizole and chlorpheniramine in children: a randomized, double-blind study.

OBJECTIVE: To assess the central nervous system side effects of chlorpheniramine and astemizole in children. DESIGN: Prospective, randomized, double-blind cross-over study. SETTING: Children were recruited from the out-patient allergy clinic and from respondents to an advertisement in a local newspaper. The study was conducted in the outpatient clinics of the ambulatory care services of the Children's Hospital of Eastern Ontario. PATIENTS, PARTICIPANTS: Children 8-16 years of age, with isolated allergic rhinitis or hay fever, were eligible for the study. We excluded children with: (1) chronic conditions (specifically asthma, atopic dermatitis, learning disabilities, or current treatment with oral corticosteroid medication); (2) known allergy to the study medications; (3) recent use of any antihistamine medication. One hundred and three children entered the study and 92 completed it. INTERVENTIONS: Children were stratified by age and randomly allocated to treatment with one of the two medication sequences. Over a period of 13 weeks both groups had 1 week of baseline studies, 3 weeks of one study medication, either chlorpheniramine or astemizole, a 6-week wash-out period and then 3 weeks of the other study medication for a second treatment period. MAIN OUTCOME MEASURES: Attention span (continuous performance test), short-term auditory and visual memory (visual aural digit span test), visual memory for geometric shapes (Benton visual retention test), motor coordination and visual-motor integration (grooved pegboard test), tapping speed and fine motor coordination (finger tapping test), physical side effects (such as sleepiness and dizziness), and compliance. RESULTS: One hundred and three patients were enrolled in the study, 92 (89%) completed the study. There were no significant drug effects on the visual retention test and the continuous performance test. On the visual aural digit span test, patients treated with astemizole scored higher than at baseline. There were no clinical or statistical differences in adverse effects between the two medications or between each medication and baseline. CONCLUSIONS: The two antihistamines studied had no adverse effects on the performance of children.

Adolescent↗
PubMed1993

Effectiveness of combined triazolam-behavioral therapy for primary insomnia.

The authors examined sleep improvement in subjects with primary insomnia who received triazolam plus behavioral therapy (N = 8) or triazolam plus sleep-related information (N = 7). At follow-up, total sleep and restedness in the morning showed greater improvement with combined triazolam-behavioral therapy and returned toward baseline in the control subjects.

Adult↗
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↗