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Biomedical subjects

R G Petty

Publications and source records attributed to R G Petty.

11 recordsLinked to original sources
PubMed1991

Diabetes is associated with a high incidence of endothelial-binding antibodies which do not correlate with retinopathy, von Willebrand factor, angiotensin-converting enzyme or C-reactive protein.

Increasing evidence implicates endothelial cell dysfunction in the development of diabetic microvascular disease, but its precise nature is elusive. This study sought to extend previous observations on the association between diabetes and the endothelial cell-derived glycoprotein von Willebrand factor (vWF), in a study of 777 diabetic patients. Compared with a mean of 1.07 +/- 0.18 iu/ml in a non-diabetic population, vWF was found to be elevated to 1.59 +/- 0.14 iu/ml in the whole sample, but particularly in those with retinopathy or microalbuminuria. It was studied whether such an elevation is part of an acute phase response, or is accompanied by other indicators of endothelial cell dysfunction. Plasma samples were examined for vWF, and serum for angiotensin converting enzyme (ACE), C-Reactive protein (CRP), IgG and IgM endothelial cell-binding antibodies (anti-EC Ig). A strong positive association was found (p less than 0.005) between the extent of elevation of vWF and the presence of diabetic retinopathy. ACE and CRP were rarely raised, and their levels did not correlate with either diabetic retinopathy or vWF levels. However, 52% of the patients had circulating anti-EC IgG or IgM, although their presence did not correlate with retinopathy, or with vWF, ACE or CRP. Thus diabetic retinopathy and probably nephropathy is associated with a specific but generalised disturbance of vascular endothelial cell function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Cutaneous blood flow responses in the forearms of Raynaud's patients induced by local cooling and intradermal injections of CGRP and histamine.

1. The cutaneous responses of the forearm to local cold exposure and intradermal injection of CGRP and other vasoactive mediators were compared in primary Raynaud's sufferers and normal volunteers. 2. Skin responses in the forearm were measured in terms of erythema reddening and skin blood flow. Visual responses were recorded by tracing and then area calculated by computerised planimetry. Skin blood flow was measured using a laser Doppler blood flow meter. 3. Cooling (5-6 degrees C for 2 min) of a 1 cm2 area of the forearm caused a localised reactive hyperaemia response in normal volunteers, measured using the last Doppler blood flow meter. The peak response in Raynaud's patients was significantly smaller than that of normal volunteers. 4. The cutaneous responses of Raynaud's patients and normal volunteers to intradermal injections of CGRP, histamine and PGE2 were not significantly different. 5. The results suggest that Raynaud's sufferers do not exhibit a diminished response to CGRP in the cutaneous microvasculature and can respond normally to histamine with an axon reflex mediated flare.

Adult↗
PubMed1989

Long term effectiveness of photocoagulation for diabetic maculopathy.

The long term visual results of photocoagulation for diabetic maculopathy were determined in 128 eyes of 95 patients followed over ten years. The mean age of patients was 55.5 years and mean follow up time was 7 years. Ten year data were available on forty patients (62 eyes) and of the remainder the majority had died. Of those eyes initially with good vision (defined as 6/12 or better), 60% maintained this level of acuity at ten years and of those which deteriorated 50% became blind (defined as 6/60 or worse). A significantly greater proportion of eyes with exudative maculopathy (48%) had good final vision compared to eyes with oedematous and ischaemic maculopathy (26%).

Adult↗
PubMed1988

Stimulation of endothelial cell growth by sera from diabetic patients with retinopathy.

An in-vitro proliferation assay has shown that sera from patients with diabetic retinopathy, particularly those with the proliferative form, are two to four times more effective than sera from non-diabetics at stimulating 3H-thymidine incorporation into both human umbilical vein and human omental microvascular endothelial cells, but not at stimulating incorporation into human dermal fibroblasts or 3T3 cells. The factor(s) is heat stable and of molecular weight greater than 15,000, and its presence is unrelated to metabolic control. It is not present in patients with other forms of diabetic vascular disease, which suggests that it is not related to carbohydrate or lipid metabolism. These results provide evidence against the hypothesis that metabolic disturbances are central to the development of diabetic microvascular disease, and raise possibilities of novel forms of therapeutic intervention.

Cell Division↗
PubMed1983

Double blind comparison of mefenamic acid and acetaminophen (paracetamol) in migraine.

We have assessed the role of mefenamic acid, a non-steroidal anti-inflammatory drug known to inhibit both the synthesis and actions of prostaglandins, as an analgesic in migraine by comparing it with the established analgesic paracetamol (acetaminophen) in a double-blind cross-over trial. Forty ambulant migraine patients were supplied with oral medication for six consecutive attacks; metoclopramide 10 mg was administered in all attacks, and paracetamol 500 mg and mefenamic acid 500 mg for three attacks each. The patients recorded the intensity of the headache at the time the medication was taken, and again after 3 hours, on a linear analogue scale. Twenty-two patients completed the trial satisfactorily. Seven had insufficient attacks and the remainder were lost to follow-up. The mean reduction in headache intensity was 36 +/- 11% on mefenamic acid and 27 +/- 10% (both mean +/- SEM) on paracetamol. While this difference is not quite statistically significant (0.1 greater than P greater than 0.05) there still remains a 28% probability that mefenamic acid is twice as potent as an analgesic. The responses in each individual patient to the two drugs were very closely correlated (P much less than 0.001). Our failure to demonstrate a convincing difference between the two analgesics leads us to speculate that peripheral prostaglandin mediated pain pathways, in which paracetamol is inactive, may be less important than central pathways, which are inhibited by both drugs.

Acetaminophen↗
PubMedDate not supplied

The influence of hypoglycaemic agents on the growth and metabolism of human endothelial cells.

Using human umbilical vein endothelial cells, and human microvascular endothelial cells from omental and subcutaneous fat obtained at laparotomy, we studied the effects of sulphonylureas and the biguanide metformin on endothelial cell proliferation, prostacyclin production, ecto-5'-nucleotidase activity, and von Willebrand factor release. Each drug produced a concentration-dependent proliferation of umbilical vein but not of microvascular endothelial cells. The stimulation of umbilical vein endothelial cell proliferation by sulphonylureas, but not by metformin, was serum- and insulin-dependent. Sulphonylureas and metformin had no effect on the proliferation of human dermal fibroblasts, smooth muscle cells derived from the umbilical artery, or 3T3 cells, until concentrations greater than 100 fold those found in vivo were reached, when there was inhibition of proliferation. These agents had no effect on prostacyclin or von Willebrand factor production, or on ecto-5'-nucleotidase activity, until high concentrations were used, at levels which also inhibited proliferation. The results suggest that the sulphonylureas and metformin, may, at concentrations found in vivo, induce changes in the turnover of endothelial cells from large vessels, but not of microvascular endothelial cells.

3T3 Cells↗