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Biomedical subjects

J S Corcoran

Publications and source records attributed to J S Corcoran.

7 recordsLinked to original sources
PubMed1987

Measurement of fingertip blood flow using thermal clearance reflects anastomotic rather than nutrient blood flow.

A thermal clearance probe was used to measure fingertip blood flow. When flow was occluded the baseline value was reproducible (coefficient of variation 2% between subjects), whereas basal and maximum flow were poorly reproducible even within subjects. Synchronous changes in thermal clearance were seen when two probes were used on fingers and toes of different limbs (r = 0.77 - 0.97), in keeping with a central control mechanism. Fingertip blood flow, as measured by thermal clearance, correlated with Po2 of venous blood draining from the dorsum of the hand (r = 0.72 - 0.92). Contralateral hand cooling caused a sharp reduction of fingertip thermal clearance by 44.2 +/- 3.7%. Thermal clearance traces were damped in fingers with heavy keratinization, and improved when keratin was removed. Comparisons with venous occlusion plethysmography (VOP) and photoelectric plethysmography (PPG) showed that thermal clearance correlates with both methods (r = 0.60 - 0.92 for VOP and 0.64 - 0.93 for PPG) but with much integration of the signal and a 10 s lag. It is concluded that the probes used measure predominantly anastomotic flow and not nutrient skin blood flow alone.

Arteriovenous Anastomosis↗
PubMed1987

Loss of spontaneous variability of fingertip anastomotic blood flow in diabetic autonomic neuropathy.

We have employed a thermal clearance probe to study fingertip blood flow, which comprises predominantly arteriovenous anastomotic flow. In non-diabetic subjects there was a marked variability in resting fingertip blood flow which was of similar magnitude to that in diabetic subjects without autonomic neuropathy. In 20 diabetic subjects with increasing severity of autonomic neuropathy there was a reduction of spontaneous variability in flow (r = 0.59, P less than 0.001), which was not related to differences in basal flow, in skin thickness or in age. There was no relationship between maximal flow and severity of autonomic neuropathy (r = 0.08), although basal flow was decreased in subjects with moderate, but not those with severe, autonomic neuropathy (P less than 0.01 and P less than .04 compared with controls). Our failure to find an increase in basal fingertip flow in autonomic neuropathy could imply that spontaneous variability of anastomic flow is lost before increased arteriovenous shunting becomes apparent, but it could result from the indirect heating employed in the study causing vasodilatation in subjects without neuropathy.

Adult↗
PubMed1986

A comparison of premixed with patient-mixed insulins.

Blood glucose control in 12 C-peptide negative patients has been compared in a crossover trial of four insulin treatment regimens: porcine soluble and isophane, premixed porcine soluble/isophane, porcine soluble and lente, all taken twice daily, and once daily bovine ultralente with three porcine soluble injections before meals. Each regimen lasted 8 weeks and included home blood glucose monitoring, telephoned advice on dose adjustment during the first 2 weeks, and home collection of seven-point capillary blood profiles for laboratory analysis. No significant differences between the regimens could be demonstrated when HbA1c, 24 h mean blood glucose, and M-values were evaluated. The average range of blood glucose values for four capillary samples taken at the same time point on different days was 8.0 mmol/l, compared with a maximum difference between regimens of 3.6 mmol/l at any time point, suggesting that blood glucose control is more heavily influenced by erratic insulin absorption than by the insulin regimen chosen. Premixed insulins offer convenience of use without significant deterioration of blood glucose control.

Animals↗
PubMed1985

How inaccurate is insulin mixing? Patient variability and syringe dead space effect.

One hundred diabetics were investigated for the accuracy and reproducibility with which they delivered a mixture of insulins. In contrast with previous reports, 80 patients delivered their total dose with a bias less than 5% from the prescribed dose and 87 with a CV less than 5%. There was little deterioration with age. The proportions of short- and intermediate-acting insulin prescribed were also delivered with commendable skill. In a separate study, syringe dead space was shown to incur a potential financial loss through insulin wastage, as well as affecting the proportions of short- and intermediate-acting insulins delivered.

Adult↗
PubMedDate not supplied

The extent of coronary artery disease in diabetic patients with myocardial infarction: an ECG study.

In 91 non-diabetics (age 63 +/- 12, mean +/- SD, years range 31-94 years) and 85 patients with known diabetes or clearly abnormal levels of HbA1c (age 66 +/- 10 years, range 36-87 years) electrocardiograms were analysed sequentially after acute myocardial infarction (AMI). There was no significant difference in infarct site between the two groups. Generalized ischaemic change without ST elevation was seen in 33% of diabetics and 22% of non-diabetics (p greater than 0.1). In patients with transmural AMI, cardiogenic shock (CGS) was significantly commoner in diabetics (relative risk 3.1, CL 1.2-8.1) but there was no difference in the frequency of reciprocal change between the two groups. In both diabetic and non-diabetic patients the development of cardiogenic shock was more frequently associated with the presence of reciprocal change, the difference reaching significance in the diabetic group (chi 2 = 4.4, p less than 0.05). Thus cardiogenic shock in both diabetic and non-diabetic patients with AMI may be associated with the presence of extensive coronary artery disease, but differences in the prevalence of extensive disease do not explain the predisposition of diabetic patients to CGS.

Adult↗
PubMedDate not supplied

Treating hypertension in non-insulin-dependent diabetes: a comparison of atenolol, nifedipine, and captopril combined with bendrofluazide.

Twenty-five of thirty NIDDS who remained hypertensive (diastolic greater than 95 mmHg supine) after 4 weeks on bendrofluazide 2.5 mg daily (B), completed a single-blind, observer-blind randomized crossover study, in which the additional use of atenolol (50 mg daily) (A), slow-release nifedipine (20 mg twice daily) (N), and captopril (25 mg twice daily) (C) was compared. Patients took each drug for 8 weeks with dose doubling at 4 weeks if supine diastolic remained greater than 90 mmHg. All three combinations were more effective than bendrofluazide alone (p less than 0.01). In nine patients studied 2 h after tablets at the end of each treatment period nifedipine was more effective than the other two drugs (B:174/104 mmHg, A:162/95 mmHg, -8%, N:141/88 mmHg, -17%, C:157/94 mmHg, -10%, supine), whereas in 16 patients studied 15 h after their evening dose there was no significant difference. Fasting insulin and HbA1 levels were not significantly different between groups. No drug had a significant adverse effect on creatinine, glomerular filtration rate, overnight urinary albumin excretion or foot transcutaneous oxygen levels (43 degrees C). All three drugs studied were effective without deleterious effects on renal function or peripheral blood flow.

Antihypertensive Agents↗