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Biomedical subjects

C Clyne

Publications and source records attributed to C Clyne.

7 recordsLinked to original sources
PubMed1991

Adrenergic and cholinergic regulation of cortisol secretion from the zona fasciculata/reticularis of bovine adrenal cortex.

Inner zone cells, isolated from bovine adrenal cortex, secrete cortisol in response to both adrenergic and cholinergic agonists. The response to adrenaline (and other catecholamines) appears during culture, is evident by 24 h and reaches a maximum by 48-72 h, but is absent in freshly isolated cells. Pre-incubation of cultured cells with adrenaline leads to homologous desensitisation; the possibility that this may explain the absent response in freshly isolated cells is discussed. Cells show a dose-dependent cyclic AMP response but no increased membrane phosphoinositide turnover. In agreement, cortisol secretion is blocked by beta-receptor, but not alpha-receptor, antagonists. Schild analysis established that the response occurs through binding to a beta 1-receptor subtype, consistent with adrenergic innervation as opposed to an effect of circulating catecholamines. In contrast, cortisol secretion to AcCh was present in both freshly isolated cells and those in culture, reaching a maximum by 48-72 h in culture. The response was specifically blocked by muscarinic, but not nicotinic, antagonists. No effect on cyclic AMP formation was observed, but dose-dependent stimulation of phosphoinositide turnover occurred. HPLC analysis of the time-course of appearance of 3H-inositol labelled head groups (from cells pre-labelled with 3H-inositol) confirmed that AcCh activates a phosphoinositidase C. Intracellular Ca2+ oscillations were also measured from fura-2 loaded single cells in response to AcCh. Together with other pharmacological studies, these observations establish that AcCh acts through a M3 muscarinic receptor subtype in these cells. The possible significance of these findings in vivo is discussed.

Acetylcholine↗
PubMed1991

Accuracy of rhythm classification using a data log system in implantable cardioverter defibrillators.

Because the presence or absence of symptoms alone may be insufficient to correctly diagnose the rhythm for which implantable cardioverter defibrillator therapy is delivered, we hypothesized that the addition of data log information available in Telectronics ATP 4210 may improve the accuracy of rhythm classification. With this system the recorded ventricular electrogram cycle length is reported on a beat-to-beat basis immediately before, during, and after the tachyarrhythmia is detected. Using this information recorded from the data log in 32 separate tachyarrhythmia episodes in 20 patients, we compared the sensitivity, specificity, and predictive accuracy of rhythm classification on the basis of symptoms alone, data log alone, and data log combined with symptoms. While classification based on symptoms alone is highly specific (10/10 episodes), it is insensitive and has an overall predictive accuracy of 53%. By contrast, data log is sensitive (90%) and specific (91%) with better predictive accuracy (94%) than symptoms alone (P = 0.002). The addition of symptoms to information on beat-to-beat cycle length from data log resulted in a slight increase in predictive accuracy.

Data Collection↗
PubMed1991

Heparin pharmacokinetics and in vitro anticoagulant activity in patients receiving nonionic radiographic contrast media.

Nonionic radiographic contrast media are used frequently in diagnostic and interventional angiography. However, there is concern that they may possess thrombogenic properties, and some studies have suggested that patients receiving nonionic contrast media are difficult to systemically anticoagulate with intravenous heparin. To investigate the potential effects of nonionic contrast media on systemic anticoagulation during diagnostic cardiac catheterization, pharmacokinetics and in vitro anticoagulant activity following a 3,000 U intravenous heparin bolus were assessed in 12 patients assigned randomly to either an ionic or a nonionic contrast agent. Independent of contrast agent, all patients exhibited biphasic (nonlinear) heparin pharmacokinetics characterized by an initial rapid disappearance phase, followed by a second slower phase. Each patient achieved a therapeutic plasma heparin concentration (greater than or equal to 0.2 U/ml) within 10 min of receiving the bolus, and maintained this level throughout the procedure. Heparin anticoagulant activity, as estimated by a standard activated partial thromboplastin time (APTT) was not affected differently by nonionic as compared with ionic contrast media (p greater than 0.05). Each patient rapidly achieved a level of systemic anticoagulation commonly considered therapeutic (APTT greater than or equal to 1.5 times the control), and maintained this level throughout the procedure. In both groups, APTT correlated directly with plasma heparin concentration (r = 0.95; p less than 0.0001), and inversely with the total amount of contrast media used during the procedure (r = -0.25; p = 0.01). Plasma heparin concentration did not correlate with total contrast media (r = -0.16; p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation↗
PubMed1989

Femoro-popliteal versus femoro-distal bypass grafting for limb salvage in patients with an "isolated" popliteal segment.

In a prospective, multicentre trial, 59 patients with an ischaemic limb and an "isolated" popliteal segment on angiography were randomised to undergo infrainguinal bypass grafting to either the popliteal segment or to a reconstituted distal vessel lower in the calf. Limb salvage was attained with 88% of the femoro-popliteal grafts and 80% of the femoro-distal grafts. There was no difference in the one year graft patency rate between the femoro-popliteal group (79%) and the femoro-distal group (70%). Mean postoperative increase in ankle/brachial pressure index was similar in the two groups despite the presence of occluded or significantly diseased vessels distal to the popliteal anastomoses. Technical difficulties were encountered in 8% of the popliteal group and 24% of the distal group. Femoro-distal bypass grafting confers no apparent benefit over femoral bypass grafting into a patent popliteal segment, even though the popliteal run-off is impaired or occluded.

Aged↗
PubMed1979

Day-bed units.

Explore the source record for details and available documents.

Ambulatory Surgical Procedures↗
PubMed1979

Reduction of blood viscosity following plasma exchange.

The effect of plasma exchange with plasma protein fraction on blood viscosity was determined in seven hyperlipoproteinaemic patients with coronary or peripheral vascular disease. This resulted in decreases in whole blood viscosity of 83% and 30% respectively at the lowest and highest shear rates studied, and decreases of 21% and 59% in plasma viscosity and fibrinogen. Serum cholesterol and triglyceride were reduced by 66% and 48% respectively. Sequential studies in two patients showed that blood viscosity returned to near-basal values by the 6th day. These findings suggest that plasma exchange may result in short-term enhancement of blood flow in vessels where low shear rates predominate.

Adolescent↗