Biomedical subjects

S Redmond

Publications and source records attributed to S Redmond.

33 records · Page 2Linked to original sources

PubMed1985

The glomerular hyperfiltration of diabetes is not associated with elevated plasma levels of glucagon and growth hormone.

Plasma concentrations of glucagon, growth hormone and glucose were measured hourly during an ordinary treatment day in 11 Type 1 (insulin-dependent) diabetic patients with high glomerular filtration rate, 11 Type 1 diabetic patients with normal glomerular filtration rate matched for age, diabetes duration and sex, and five healthy control subjects, simultaneously with the measurement of the glomerular filtration rate using 51Cr EDTA clearance. Plasma glucagon profiles were not statistically distinguishable (p = 0.49) from control values in either group, although they were somewhat lower in the hyperfiltering group. Plasma growth hormone values were higher than control (p = 0.07) in both diabetic groups, but were not different between these two groups (p = 0.94). All indices of glycaemic control (glycosylated haemoglobin, urinary glucose excretion, and plasma glucose concentration) were higher in the hyperfiltering group, although no single index reached statistical significance. No correlations between concentrations of these substances and glomerular filtration rate were found. Elevated plasma concentrations of glucagon and growth hormone do not characterise those diabetic patients with high glomerular filtration rate.

Adolescent↗

PubMed1985

A comparative study of the portable regional CBF monitor and the portable mean hemispheral CBF monitor: advantages and disadvantages in clinical practice.

CBF determination can provide additional valuable information which can be used in clinical practice to enhance our capabilities in patient evaluation. The initial techniques requiring intraarterial injections have been largely replaced by the noninvasive inhalation and intravenous methods. The recent refinement of microcomputers and the development of portable CBF monitors have made CBF determination a nontraumatic, dependable and easily repeatable examination at the patient's bedside. In this communication we compare a portable region CBF monitor and a portable mean hemispheral CBF monitor; we study their advantages and disadvantages in clinical practice. Emphasis is placed on the practical characteristics and the information provided by each monitor and its contribution to patient evaluation. Illustrative cases are presented.

Brain↗

PubMed1985

Mean hemispheral cerebral blood flow changes after craniotomy. Significance and prognostic value.

The effects of craniotomy on cerebral haemodynamics remains controversial from a study of the literature. This report represents our experience with respect to CBF changes within 10 days of surgery. Our objective was twofold, first to study the effect of craniotomy on the cerebral circulation and second to determine whether the CBF pattern at different post-operative intervals could provide useful prognostic information. A total of 135 CBF measurements were performed at the bedside of 36 patients; 19 patients with an assortment of intracranial tumours and 17 patients with intracranial aneurysm in different clinical grades. Our results indicate a significant rise in CBF in the immediate post-operative period averaging 18% of the pre-operative value. We believe this reflects a normal reaction of the cerebral vasculature to the inevitable disturbance of surgery. Furthermore, this hyperaemia may be of prognostic value as it was observed in 85% of the patients with tumour discharged without post-operative deficit and in 80% of the patients with aneurysms discharged in clinical grade 1 or 2. This is in sharp contrast with its development in only 16% of the patients with tumour discharged with post-operative deficit and 16% of the patients with aneurysm discharged in grade 3 or 4. The study adds to the direct clinical utility of CBF determination as a prognostic tool.

Adolescent↗

PubMed1984

Cloning and expression analysis of full length mouse cDNA sequences encoding the transformation associated protein p53.

We have cloned and sequenced overlapping cDNA fragments which together encode the entire mouse protein p53. Using these cDNA's we have reconstructed the full length coding region for the protein, and have analysed its coding potential by expression in vitro, both as a full length sequence and as a subfragment contained in a fusion protein. The predicted amino acid sequence contains no obvious homologies to any known oncogenes but includes a possible tyrosine kinase acceptor site.

Amino Acid Sequence↗

PubMed1984

Mouse mammary tumor virus can mediate cell fusion at reduced pH.

Mouse mammary tumor virus, a type-B retrovirus, was shown to mediate fusion of cultured cells following low-pH treatment. Fusion could be demonstrated both with virus-infected cells or with uninfected cells carrying freshly absorbed virus. Although the fusion response was variable between different cell lines, one line of MMTV-infected mink lung cells, designated MGR4, was particularly susceptible to fusion at reduced pH. Since expression of MMTV in these cells is strongly regulated by glucocorticoids, it was possible to demonstrate that cell fusion was dependent on MMTV-encoded functions. With MGR4 cells, a pH threshold for membrane fusion was observed, centered on pH 5.5, at which 50% of the cells were fused. At lower pHs virtually all of the cells in the monolayer fused. These results are similar to those described for other virus groups and are consistent with the idea that most enveloped animal viruses infect cells by a common mechanism involving membrane fusion triggered by low pH.

Animals↗

PubMed1984

Effect of indomethacin on cerebral blood flow, carbon dioxide reactivity and the response to epoprostenol (prostacyclin) infusion in man.

Cerebral blood flow (CBF) has been measured using a non-invasive Xenon133 clearance technique in six normal subjects after 2 days pretreatment with oral indomethacin at a dose of 100 mg/day. The results were compared with placebo given in a double blind balanced cross-over design. Indomethacin was found to result in a reduction in resting CBF of about 25% but the reactivity of the cerebrovascular circulation to carbon dioxide was preserved at normal levels. Infusions of epoprostenol (prostacyclin, PGI2) at a dose of 5 ng/kg/min resulted in a reduction of CBF of about 10% after placebo but no significant change in CBF after indomethacin. The results suggest that prostaglandins are involved in the maintenance of cerebrovascular tone but not in the mechanism of cerebral vasodilation accompanying hypercapnia. The combination of indomethacin and PGI2 has been proposed as a treatment of cerebral artery spasm and the findings suggest that the combination therapy would not be accompanied by undesirable intracerebral steal.

Adult↗

PubMed1984

Clinical use of a portable bedside cerebral blood flow machine in the management of aneurysmal subarachnoid hemorrhage.

Recent advances in electronics and microprocessors have enabled the development of a compact portable cerebral blood flow (CBF) machine capable of being transported to the patient's bedside. We have used such a device, the Novo Cerebrograph 2a, during the past 7 months on a regular basis in the day to day management of our patients with intracranial aneurysms. One hundred three studies were performed in 23 cases of suspected intracranial aneurysm. Twenty-two cases presented with acute subarachnoid hemorrhage. Patients were studied on admission, preoperatively, in the recovery room, on postoperative Days 1, 5, and 14, and whenever the clinical condition of the patient warranted. The preoperative admission grade was found to correlate well with the mean CBFisi (ISI: initial slope index). Grade III and IV patients had flows significantly lower than those of Grade I and II patients. Serial CBF measurements proved useful in the management of 18 of 22 cases admitted with acute subarachnoid hemorrhage. Delayed ischemic deficits secondary to vasospasm occurred in 6 cases, with a concomitant average fail in mean flow in the symptomatic hemispheres of 27.9%. After volume expansion, an average increase in flow of 29.7% was noted. Low preoperative flows influenced management decision-making in 8 cases. In a further 4 cases, serial CBF measurements were helpful in the differential diagnosis of new neurological signs.

Adult↗

PubMed1979

An intravenous 133xenon clearance technique for measuring cerebral blood flow.

An intravenous 133Xe clearance technique for measuring cerebral blood flow (CBF) is described. Results obtained compared well with those using the intracarotid 133Xe technique. The reproducibility of the method was checked by repeating measurements within a few hours in 14 patients, when no significant overall change occurred, and after some days in 23 patients when a mean fall in flow of 8% was observed. CBF was measured in 52 control subjects. The mean fast component flow (Ff) was 68.6 ml/100 g/min (SD 11.3). No difference between the two hemispheres was found. Flow was confirmed to be higher anteriorly in the cerebral hemispheres. A significant inverse correlation was found between CBF and age.

Age Factors↗

PubMed1979