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Biomedical subjects

B Williams

Publications and source records attributed to B Williams.

At least 307 records · Page 17Linked to original sources
PubMed1993

Nurse triage.

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Emergency Nursing↗
PubMed1993

Surgery for hindbrain related syringomyelia.

Syringomyelia is a condition with many possible causes, the commonest of which seems to be an abnormality at the foramen magnum. Such cases may be grouped under the heading of "Hindbrain related syringomyelia" and the principles of treatment for all such cases are largely similar. The commonest of these foramen magnum region abnormalities is hindbrain herniation which may be associated with a history of birth difficulties, a small posterior fossa, segmentation abnormalities of the cervical vertebrae or the base of the skull, arachnoiditis of the subarachnoid spaces, subarachnoid pouches, hydrocephalus and intracranial tumours or tumours partly blocking the foramen magnum. Other causes of syringomyelia include conditions which could be grouped under the heading of "non-hindbrain related syringomyelia", these mostly produce blockage of the spinal subarachnoid spaces, especially spinal "arachnoiditis" or meningeal fibrosis, including that secondary to traumatic paraplegia. Intraspinal tumours are sometimes cystic and some authors have included this association under the heading of syringomyelia. Syringomyelia of all kinds is almost always a surgical condition, the destructive forces are those of fluid distending the tissues. As a principle, treatment directed against the cause of the accumulation and the intracord propagation of the fluid by normalising the CSF pathways is more likely to be successful than drainage of the cavities. Drainage operations have an inevitable failure rate and a further incidence of complications attends myelotomy and the leaving of any drainage tube within the narrow confines of the spine. Correction of craniospinal pressure dissociation and re-establishment of a cisterna magna appears to be the most successful treatment strategy and is likely to be immediately and permanently successful in correcting not only the pressure problems such as long tract involvement and syringobulbia features but also in producing satisfactory clinical and radiological improvement in the syringomyelia. The recommended technique includes radical means to gain space at the foramen magnum by creating a large artificial cisterna magna, resecting part of the tonsils, preventing the descent of the cerebellum and avoiding the use of space occupying or fibrosis producing dural grafts. Because the pathogenesis of the cavities remains in doubt, the method by which this treatment stratagem is effective is unclear. It may be that change in the closure conditions of parts of the neuraxis, i.e., alteration in the capacitance and consequent change in pulsation characteristics afforded by the decompression may be the factor which predicates success. Surgical management of hindbrain related syringomyelia is not easy, there are hazards associated with operation, hydrocephalus demands priority in it's management.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain Neoplasms↗
PubMed1993

Polyarthropathy--a delayed reaction to low osmolality angiographic contrast medium in patients with end stage renal disease.

Since the introduction of low osmolality non-ionic media, acute reactions to radiographic contrast are uncommon and delayed reactions are especially rare, consisting mostly of mild flu-like symptoms. We report two patients suffering from end-stage renal failure and treated by continuous ambulatory peritoneal dialysis (CAPD) who developed a severe constitutional illness including acute polyarthropathy 6 and 16 h after injection of the low osmolality non-ionic contrast medium, iopamidol. Although the clinical presentation of the reactions was similar to a systemic lupus syndrome there was no immunological evidence to support this as an aetiological mechanism. Since CAPD is a relatively inefficient method of clearing contrast media prolonged high circulating levels of iopamidol may have been a contributory factor to these unusually severe delayed contrast reactions.

Acute Disease↗
PubMed1993

Effect of elevated extracellular glucose concentrations on transmembrane calcium ion fluxes in cultured rat VSMC.

Blood flow autoregulation is impaired in early diabetes mellitus, predisposing the renal microcirculation to injury. These hemodynamic changes have been strongly implicated in the development and progression of diabetic glomerulopathy. Blood flow autoregulation is predominantly a myogenic reflex which is strongly dependent on Ca2+ uptake by vascular smooth muscle cells (VSMC). Because impaired blood flow autoregulation may be responsive to glycemic control, the present study examined the effects of elevated extracellular glucose concentrations on basal, voltage sensitive and receptor operated Ca2+ uptake by VSMC. Confluent cultured rat VSMC were exposed to: (1) control medium (CM; 5 mM glucose); (2) high glucose medium (HGM; 10 to 30 mM glucose); or (3) osmotic control medium (OCM; glucose 5 mM + L-glucose 25 mM or mannitol 25 mM). A threshold glucose concentration of 15 mM markedly and maximally depressed basal Ca2+ uptake by VSMC (HGM 52% vs. CM). In addition, HGM significantly depressed voltage sensitive Ca2+ uptake by VSMC as determined by responses to BAY K 8644 (10(-7) M) or high extracellular [K+] (65 mM, HGM 50% vs. CM). HGM similarly depressed pressor hormone-stimulated Ca2+ uptake (AVP or Ang II 10(-7) M) by VSMC. The effects of HGM on Ca2+ uptake were time exposure dependent and reversible. Ca2+ uptake by VSMC in the presence of OCM did not differ from CM. Elevated extracellular glucose concentrations thus exert a direct and profound effect on basal, voltage sensitive and receptor operated Ca2+ uptake by VSMC. These observations may provide a biochemical basis for glucose-induced dysregulation of regional blood flow autoregulation in early diabetes mellitus.

Animals↗
PubMed1993

Reproductive success of cat fleas, Ctenocephalides felis, on calves as unusual hosts.

Cat fleas, Ctenocephalides felis, were released onto calves as unusual hosts, and sampled at intervals for histological examination. Egg output from fleas on age-matched male and female calves was monitored. Using indicators of reproductive maturation and regression together with egg output data, the reproductive success and fertility of cat fleas on male and female calves were estimated. Comparisons were made with fleas taken from cats. The mean egg output of fleas on the bull calf was highly significantly different from that on the age-matched female calf: 28.14 +/- 2.96 (SE) eggs/h compared with 16.21 +/- 1.96 (SE) eggs/h. A higher proportion of sampled fleas (83.0%) was reproductively mature on the feline hosts compared with the calves (45.4-62.5%). Blue bodies resulting from oocyte resorption were present in the ovarioles of 10.4-19.0% of fleas sampled from the calves. No blue bodies were present in fleas removed from cats. Eggs laid by fleas on calves were viable and larvae were reared to adulthood. The mean percentage hatching success on the age-matched male and female calves was 46.7% and 51.7%. This represents a reduction in viability of 28-33% compared with eggs laid by fleas on cats. Factors which may account for reduced reproductive maturation of fleas on calves, including protein content of the host's blood, are discussed.

Animals↗
PubMed1993

Nurse triage in theory and in practice.

'Nurse Triage' refers to the formal process of early assessment of patients attending an accident and emergency (A&E) department by a trained nurse, to ensure that they receive appropriate attention, in a suitable location, with the requisite degree of urgency. The benefits claimed for nurse triage include better patient outcomes, through clinical management reaching those in greatest need of it first. A recent study of nurse triage in a British A&E department failed to demonstrate the benefits claimed: patients undergoing triage were delayed, especially those in the most urgent groups. No differences were noted between the two study groups in levels of satisfaction with the A&E process. The results brought forth criticism from all quarters. In this paper the points made by the critics are considered, and an attempt to answer them is made.

Clinical Nursing Research↗
PubMed1993

Non-invasive diagnosis of arterial patency after thrombolytic treatment and its relation to prognosis.

OBJECTIVE: To validate a simple noninvasive method with serial creatine kinase measurements for diagnosis of early patency of the infarct related artery after thrombolytic treatment with streptokinase. To investigate the relation between early patency of the infarct related artery and prognosis. DESIGN: Patients under 76 years of age and seen within six hours of the start of prolonged chest pain and ST segment elevation were treated with streptokinase (1.5 x 10(6) U) intravenously over 30-60 minutes. Blood for measurement of total creatine kinase activity was taken at baseline and at 1, 2, 3, 4, 8, 12, 16, 20, and 24 hours after starting treatment. The rise in enzyme activity at each time from baseline was expressed as a proportion of the total rise from baseline to peak. PATIENTS: Patients studied were in the following groups: (a) Sixty patients took part in a validation study with angiographic determination of patency of the infarct related coronary artery at 2.6 (0.3) hours (mean (SD)) after starting streptokinase. (b) A further 258 patients did not have early arteriography, but data were added to those from the 60 validation patients to find the relation between enzymatically determined early patency of the infarct related artery and 30 day mortality. (c) A further subset of 232 patients with first infarctions (including patients from groups (a) and (b) had angiocardiography at three weeks after infarction, and data were used to investigate the relation between early patency of the infarct related artery and left ventricular function. MAIN OUTCOME MEASURES: Normalised rate of rise of creatine kinase activity at three hours after starting streptokinase in relation to angiographic patency of the infarct related coronary artery at 2.5 hours; 30 day cardiac mortality; and left ventricular function at three weeks in survivors of first infarction. RESULTS: In the validation study, a rise in three hour creatine kinase activity of > 20% of peak occurred in 34/37 patients with initially patent infarct related coronary arteries (sensitivity 92%), and a rise to < 20% of peak occurred in 21/23 patients with initially occluded arteries (specificity 91%). In the prognostic study, 30 day mortality was 2.1% in the 191 patients with three hour creatine kinase > 20% of peak and 8.7% in the 127 patients with three hour creatine kinase < 20% of peak (p < 0.01). Angiocardiography in three week survivors of anterior infarction (n = 95) showed better left ventricular function when three hour creatine kinase was > or = 20% than when it was < 20% of peak (mean (SEM) end systolic volume 71 (5) v 96 (9) ml, p < 0.02; ejection fraction 56% (2%) v 51% (2%), NS). CONCLUSION: Non-invasive determination of early patency of the infarct related artery by the normalised rate of rise of creatine kinase activity at three hours seems to be reliable, and may be prognostically important and of value for use in clinical trials.

Adult↗
PubMed1993

Aspirin does not improve early arterial patency after streptokinase treatment for acute myocardial infarction.

OBJECTIVE: To investigate the hypothesis that the magnitude of the life saving effect of aspirin in the second international study of infarct survival (ISIS-2) trial cannot be explained solely by prevention of late reocclusion of the infarct related artery. The aim of this study was to discover whether or not aspirin in combination with streptokinase had an adjuvant thrombolytic effect. DESIGN: Aspirin (150 mg) or placebo was given at the start of streptokinase infusion to 200 patients seen within six hours of the start of prolonged ischaemic cardiac pain and ST segment elevation. All patients received active aspirin at three hours. Patency of the infarct related artery was assessed non-invasively by the normalised rise of creatine kinase activity at three hours after starting streptokinase in these 200 patients and in a further 52 patients who had already taken aspirin within one week of the start of infarction. MAIN OUTCOME MEASURE: Rise in creatine kinase activity from baseline to > or = 20% or < 20% of the peak rise of activity in blood taken at three hours after starting infusion of streptokinase. This correlates with patency or occlusion of the infarct related coronary artery at about 2.5 hours after starting streptokinase. RESULTS: Assessed in this way, patency of the infarct related artery was 60% in patients given aspirin, 63% in those given placebo, and 62% in patients who had already taken aspirin within one week of infarction. CONCLUSION: The magnitude of the life saving effect of aspirin remains unexplained. Further investigation is needed into the mechanism of action of antiplatelet treatment in relation to thrombolytic treatment.

Aged↗
PubMed1993

Differences in priorities assigned to patients by triage nurses and by consultant physicians in accident and emergency departments.

STUDY OBJECTIVES: To investigate whether the greater urgency assigned to accident and emergency patients by triage nurses than by accident and emergency doctors was uniform across all patient groups. DESIGN: Patients attending an accident and emergency department between 8.00 am and 9.00 pm over a six week period were assessed prospectively for degree of urgency by triage nurses, and retrospectively for urgency by one of two consultant accident and emergency doctors. Patients were grouped according to their clinical mode of presentation. SETTING: An accident and emergency department of a district general hospital in the Midlands, UK, in 1990. PATIENTS: 1213 patients who presented over six weeks. MEASUREMENTS AND MAIN RESULTS: As might be expected, patients' conditions were assessed as being more urgent prospectively than retrospectively. This finding, however, was not uniform across all patient groups. Nurses' assessments of urgency tended to favour children and patients who presented with eye complaints and gave less priority to medical cases, particularly those with cardiorespiratory symptoms. CONCLUSIONS: These findings have implications for all those involved in the organisation of triage systems and in the training of nurses in accident and emergency departments. It is essential that judgements on how urgently patients need to be seen are made in a completely objective manner.

Age Factors↗
PubMed1993

Glucose-induced protein kinase C activity regulates arachidonic acid release and eicosanoid production by cultured glomerular mesangial cells.

Changes in glomerular eicosanoid production have been implicated in the development of diabetes-induced glomerular hyperfiltration and glomerular mesangial cells (GMC) are major eicosanoid-producing cells within the glomerulus. However, the mechanism for the effect of diabetes mellitus on glomerular mesangial eicosanoid production is unknown. The present study therefore examined whether elevated glucose concentrations activate protein kinase C (PKC) in GMC and whether this PKC activation mediates an effect of elevated glucose concentrations to increase the release of arachidonic acid and eicosanoid production by GMC. The percentage of [3H]arachidonic acid release per 30 min by preloaded GMC monolayers was significantly increased after 3-h exposure to high glucose (20 mM) medium (177% vs control medium) and this increase was sustained after 24-h exposure to high glucose concentrations. 3-h and 24-h exposure to high glucose medium also increased PGE2, 6-keto-PGF1 alpha, and thromboxane (TXB2) production by GMC. High glucose medium (20 mM) increased PKC activity in GMC at 3 and 24 h (168% vs control). In contrast, osmotic control media containing either L-glucose or mannitol did not increase arachidonic acid release, eicosanoid production, or PKC activity in GMC. Inhibiting glucose-induced PKC activation with either H-7 (50 microM) or staurosporine (1 microM) prevented glucose-induced increases in arachidonic acid release and eicosanoid production by GMC. These data demonstrate that elevated extracellular glucose concentrations directly increase the release of endogenous arachidonic acid and eicosanoids by GMC via mechanisms dependent on glucose-induced PKC activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗