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Biomedical subjects

V Williams

Publications and source records attributed to V Williams.

At least 19 recordsLinked to original sources
PubMed2001

Preliminary characteristics of the prothrombin converting enzyme from venom of Stephen's banded snake (Hoplocephalus stephensii).

Stephen's banded snake (Hoplocephalus stephensii) is an infrequently encountered Australian elapid species. The crude venom contains coagulant activity and the component responsible is a prothrombin activator requiring factor V for activity. SDS-PAGE of the isolated native protein revealed two bands at 23 and 36 kDa. These findings indicate that the procoagulant is similar to that found in the Australian tiger snake (Notechis scutatus) and thus resembles factor Xa.

Animals↗
PubMed2001

Reliability and validity of a modified Colorado Symptom Index in a national homeless sample.

This study examined the reliability and construct validity of a modified version of the Colorado Symptom Index (MCSI), a brief, self-report measure of psychological symptomatology, in a study of interventions to prevent homelessness. Eight projects in a national, cooperative study collected new data at baseline, 6, and 12 months using a set of common measures as well as site-specific instruments. The pooled sample consisted of 1,381 persons in treatment for mental illness or substance abuse (or both), of which 84% had a history of homelessness. The analyses employed classical and Rasch methods to examine the MCSI's content validity, internal consistency and item quality, test/retest reliability, dimensionality, appropriateness for the sample, construct validity, and responsiveness to change. This 14-item scale was found to be a reliable and valid measure of psychological symptoms in this sample. Its content was consistent with other symptom measures, its high internal consistency and test-retest coefficients supported its reliability, its relationships to other measures indicated that it had good construct validity, and it was responsive to change. We conclude that the MC

Adolescent↗
PubMed2000

Central venous catheter placement in patients with disorders of hemostasis.

BACKGROUND: Patients requiring central venous access frequently have disorders of hemostasis. The aim of this study was to identify factors predictive of bleeding complications after central venous catheterization in this group of patients. METHODS: A retrospective analysis of all central venous catheters placed over a 2-year period (1997 to 1999) at our institution were performed. The age, sex, clinical diagnosis, most recent platelet count, prothrombin international normalized ratio (INR), activated partial thromboplastin time (aPTT), catheter type, the number of passes to complete the procedure, and bleeding complications were retrieved from the medical records. RESULTS: In a 2-year period, 2,010 central venous catheters were placed in 1,825 patients. Three hundred and thirty placements were in patients with disorders of hemostasis. In 88 of the 330 patients, the underlying coagulopathy was not corrected before catheter placement. In these patients, there were 3 bleeding complications requiring placement of a purse string suture at the catheter entry site. In the remaining 242 patients, there was 1 bleeding complication. Of the variables analyzed, only a low platelet count (<50 x 10(9)/L) was significantly associated with bleeding complications. CONCLUSION: Central venous access procedures can be safely performed in patients with underlying disorders of hemostasis. Even patients with low platelet counts have infrequent (3 of 88) bleeding complications, and these problems are easily managed.

Blood Coagulation Disorders↗
PubMed1999

Pregnancy and perinatal outcomes in migraineurs using sumatriptan: a prospective study.

BACKGROUND: Sumatriptan is an acute treatment for migraine which is often used by women in their child-bearing years, and who become unexpectedly pregnant. Within the context of the post-marketing use of sumatriptan injection for the acute treatment of migraine, and in compliance with approved labeling, we wished to compare perinatal pregnancy outcomes in women who did and did not use the drug after conception. METHODS: Open-label, prospective study conducted in 12,339 migraineurs (including 9,861 women) whose demography and consumption pattern of sumatriptan injections were typical, and were predicted to include 150 pregnancies. Outcome of pregnancy was the end-point. RESULTS: There were 168 of 173 pregnancies that were well-documented. Sumatriptan was only used prior to conception in 92 cases. There were 76 first trimester exposures to sumatriptan. There were no differences in pregnancy outcome between the two groups. CONCLUSIONS: Perinatal and pregnancy outcome did not differ between patients who had and had not used sumatriptan after conception, at the resolution of these sample sizes. This study design complements the ongoing pregnancy registry, which is now widened to patients exposed to all formulations of sumatriptan.

Abortion, Spontaneous↗
PubMed1999

Investigation of female survival benefit in metastatic melanoma.

Epidemiological studies show female survival benefit in advanced metastatic melanoma. In investigating a possible mechanism for this female survival benefit, we have previously reported that the female steroid 17beta-oestradiol significantly reduces invasion of a human melanoma cell line (A375-SM cells) and ocular melanoma cells through fibronectin. Neither cell type was found to possess oestrogen receptor-alpha. The aim of the current study was to obtain further information on the extent to which progression of cutaneous melanoma might be sex steroid sensitive by (a) examining the relationship between circulating sex steroids, sex hormone binding globulin and disease progression; (b) examining the relationship between sex steroid structure and the ability of steroids to reduce invasion of a melanoma cell line in vitro; and (c) examining the effects of sex steroids on proliferation of these cells in vitro. We report a significant reduction in circulating oestrone with disease progression in male but not female patients. Examining steroids for their ability to inhibit invasion of A375-SM cells through fibronectin in vitro, oestrogenic compounds (17beta-oestradiol and oestrone) were found to inhibit invasion; in this respect, oestrone was approximately 50 times more potent than 17beta-oestradiol; steroids lacking the benzene ring structure did not inhibit invasion, indeed dehydroepiandrosterone (DHEA) which acts as a precursor to androgenic steroids significantly enhanced invasion. Proliferation of A375-SM cells was unaffected by 17beta-oestradiol, oestrone or dihydrotestosterone when cells were cultured on plastic; in contrast, all three steroids induced modest proliferation of cells when grown on fibronectin with dihydrotestosterone the most mitogenic of the three steroids. These data are consistent with sex steroids playing a role in melanoma progression.

Adolescent↗
PubMed1999

AHCPR-funded rural managed care centers: report from the field.

In 1994, the Agency for Health Care Policy and Research awarded cooperative agreements to five University-based groups to promote the establishment of managed care institutions and development of rural health networks. This paper summarizes the experiences of these rural managed care centers in the first three years of this initiative. Key ingredients for achieving the project's goals that are identified by the project directors are reported as "foundations" that must be in place from the outset, or "building blocks" that can be developed along the way. The development of information systems and efforts to foster leadership in the medical community are areas in which grant funding of this type can be most effective.

Community Networks↗
PubMed1999

Snakebite?

Explore the source record for details and available documents.

Adult↗
PubMed1998

Rural attachments for students in the health professions: are they worthwhile?

In the period 1991-96, 156 undergraduates from 14 health disciplines at the University of Sydney completed rural attachments in rural and remote areas of Australia as part of the Rural Careers Project. On return from their attachment, students were encouraged to write a brief report of their experiences. Ninety-two available reports were analysed as one means of assessing the success of the attachments with respect to informing students about rural health issues and stimulating their interest in rural careers after graduation. A content analysis of the students' written comments about their perceptions and experiences was completed. Students were extremely positive about the value of the attachments and expressed more positive than negative comments regarding their perceptions of rural life and work. The results show that rural attachments are indeed worthwhile learning opportunities.

Allied Health Personnel↗
PubMed1997

Abbreviated educational session improves cranial computed tomography scan interpretations by emergency physicians.

STUDY OBJECTIVE: Previously published research (phase I) demonstrated a concerning misinterpretation rate of cranial computed tomography (CT) scans by emergency physicians. This study (phase II) determined whether an abbreviated educational session would improve emergency physician interpretation skills of cranial CT scans. METHODS: Participants in this prospective, interventional study in a county hospital ED were patients undergoing cranial CT scanning during ED evaluations and attending level emergency physicians. An abbreviated educational session on cranial CT interpretation skills was given to the same attending emergency physicians who participated in phase I. The educational session included basic CT interpretation skills and misinterpreted CT scans from phase I. We determined the postsession accuracy rate of the emergency physicians on 324 ED patient CT scans. The CT interpretation accuracy rates were then compared between phase I and phase II to determine the effectiveness of the educational session. RESULTS: The radiology/ED CT scan concordance rate improved from 61.3% (kappa = .22) to 88.6% (kappa = .70; P < .0001). Potentially clinically significant CT scan misinterpretations decreased from 24.1% to 4.0% (P < .0001). Most importantly, major missed findings on CT scans decreased from 11.4% to 2.8% (P < .0001). Continuous quality improvement monitoring found no instance of clinically significant patient mismanagement. CONCLUSION: Within the limits of this study, we conclude that emergency physicians' interpretation skills of cranial CT scans may be improved using a 1-hour educational session.

Brain Diseases↗
PubMed1996

Comparison of measures of exposure to asbestos in former crocidolite workers from Wittenoom Gorge, W. Australia.

Determinations of exposure-response relationships between crocidolite and the major asbestos-related diseases in the Wittenoom cohort have previously depended on the validity of estimates of airborne exposure to asbestos. This work aims to validate the airborne exposure measurements by obtaining measurements of the concentrations of uncoated crocidolite fibers and asbestos bodies retained in the lungs of individual workers, and to estimate the half-life of crocidolite fibers in the lungs. Samples of lung tissue, excluding tumor, of all former Wittenoom workers known to have died in Western Australia (WA) were sought from teaching hospitals, pathology departments, and the Coroner's pathologist. The lung specimens were processed using Pooley's method with TEM for counts of fibers of all types and using Smith and Naylor's method with conventional light microscopy for asbestos bodies (AB). Multiple linear regression was utilized to examine the associations between crocidolite concentrations in the lung and duration of employment at Wittenoom, time since last employed at Wittenoom, nature of job, estimated average fiber concentration at the worksite, and estimated cumulative crocidolite exposure (CCE) in fiber-years/ml for each subject. Lung tissue from 90 cases was processed and there was good agreement between counts of crocidolite fibers, asbestos bodies, and CCE. Correlations were 0.77 for AB and fibers, 0.54 for AB and CCE, and 0.58 for CCE and fibers, after log transformation. The half-life of crocidolite fibers in the lung was estimated at 92 months (95% CI 55-277 months). Previous estimates of airborne exposure to Wittenoom crocidolite have been reasonably reliable. The relatively simple technique of light microscopy for counting ABs in lung tissue also provides a useful and reliable indication of the level of past occupational exposure to crocidolite in subjects whose exposure has been only to crocidolite. The half-life of crocidolite fibers in the lungs of former Wittenoom workers is about 7-8 years.

Adult↗
PubMed1996

Pseudomonas fluorescens adhesion and transport through porous media are affected by lipopolysaccharide composition.

The objectives of this work were (i) to use transposon mutagenesis to produce mutants of Pseudomonas fluorescens that were altered in adhesion ability and transport through porous media and (ii) to identify the alterations in surface characteristics that were responsible for the changes in attachment. Mutants of P. fluorescens were generated with TnphoA, which enabled identification of mutants that were altered in surface proteins. Transposon mutants were screened for alterations in adhesion ability by attachment assays on hydrophobic polystyrene and water-wettable polystyrene. Four TnphoA mutants with increased adhesion to the hydrophobic surface and decreased adhesion to the water-wettable surface were obtained. Transport of the strains through porous media was evaluated by passing suspensions of each mutant and the parent through columns containing quartz sand and determining the number of cells retained in the columns. The mutants all demonstrated increased adhesion and retention in the columns. Southern analysis demonstrated two types of mutants with separate transposon insertion sites. Polyacrylamide gel electrophoresis of the strains demonstrated that the O antigen on the lipopolysaccharide was either attenuated or absent. Lack of this polysaccharide, and the consequent increased exposure of the lipid moiety of the lipopolysaccharide, is probably responsible for the increase in adhesion to the hydrophobic substrata and retention in the sand column. This work combined with previous studies of attachment of P. fluorescens demonstrates that more than one type of polymer can mediate the adhesion of this organism to nonbiological surfaces.

Bacterial Adhesion↗
PubMed1996

Cocaine-associated intracranial hemorrhage: absence of vasculitis in 14 cases.

Complications associated with the use of cocaine are varied, and include cerebral hemorrhage and ischemia, with vasculitis and vasospasm as possible etiologies. We reviewed selected brain samples from 14 autopsy cases of cocaine-related cerebrovascular disease. Intracerebral or subarachnoid hemorrhage was present in 12 cases. Intracranial arterioles were either normal or showed nonspecific changes. From these observations, we suggest that intracranial hemorrhages occur in the absence of readily detectable vascular abnormalities.

Adult↗
PubMed1995

Asbestos bodies in lung tissue following exposure to crocidolite.

A series of 206 necropsies in Western Australia (WA) have had routine counts made of asbestos bodies in samples of lung tissue using conventional light microscopy. Thirty-two cases had worked in the asbestos industry at Wittenoom, WA and (log) counts of asbestos bodies in their lung tissue correlated well with estimates of their (log) cumulative airborne exposure to crocidolite fibers (r = 0.60). There was no association between the number of asbestos bodies and time since exposure to asbestos ceased. In subjects without known exposure to asbestos, there was a weak but nonsignificant increase in number of asbestos bodies with increasing age, with 26% of cases having no asbestos bodies present. It is concluded that the relatively simple technique of light microscopy for counting of asbestos bodies in lung tissue provides a reliable indication of the level of past occupational exposure to crocidolite in subjects whose exposure has been only to crocidolite. This could be extremely useful in follow-up studies of cohorts that lack reliable measures of airborne exposure to crocidolite asbestos.

Adult↗
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↗