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Buphenine (nylidrin), a β-adrenergic agonist, is used therapeutically for its vasodilating effect on the peripheral circulation and possibly on the cerebral circulation as well. In spite of its ophthalmic usage in degenerative retinal disease and glaucoma, buphenine's ocular effects and their mechanisms are not sufficiently established. Consquently, we studied the action of 4.5-120 μM buphenine in isolated, arterially perfused cat eyes, and then used light-evoked electrical signals, perfusion flow rates and the diameters of the retinal vessels as parameters for the drug's effect. Our findings showed that buphenine induced a marked, dose-related, reversible increase in the amplitude of the electroretinogram (ERG) b-wave, a decrease in the c-wave, but no significant changes in the standing potential and light peak of the DC-ERG. The compound action potential of the optic nerve revealed dose-dependent and reversible changes in configuration. However, the flow of perfusate was not affected by the drug, and the diameter of retinal vessels did not change significantly. Our studies suggest that the interaction of buphenine with retinal adrenergic receptors is not related to the vasculature present but to elements involved in information processing. It is likely that these receptors are linked to neurons, since the β-agonist affected the ERG b-waves as well as the compound action potential of the optic nerve. [ABSTRACT FROM AUTHOR]

The relationship between the development of microvascular incompetence and the loss of potential for functional recovery following cardioplegia was investigated using St. Thomas' Hospital No. 2 solution (STH) in isolated working rat hearts. Cardiac function was measured prior to cardioplegia and again after 30 min of reperfusion at 37°C following 1, 2 or 4 h arrest at 30°C (n=5). The hearts were then fixed by perfusion with 2·5% glutaraldehyde and then nuclear track emulsion was perfused as an intravascular marker of competent capillaries. Following cardioplegia for 1 h hearts showed 95·4% recovery of aortic flow in the working mode, and a high proportion of the capillaries in the subendocardial (84·6 ± 2·3%), middle (94·6 ± 3·0%) and subepicardial (89·1 ± 4·9%) thirds of the left ventricular myocardium transmitted perfusate. Two hours arrest resulted in significantly diminished recover of left ventricular function (aortic flow: 56·6 ± 7·6% and aortic pressure: 64·4 ± 2·5% of pre-arrest values), but microvascular competence was not reduced Hearts arrested for 4 h did not recover useful levels of left ventricular function (aortic flow 0%, aortic pressure 6 ± 2·5% and heart rate 56·0 ± 23·1%). This loss of the remaining two thirds of the potential for functional recovery was associated with significant (<0·01) reductions in the proportions of competent capillaries (subendocardial, middle and subepicardial thirds to 10·9%, 19·2% and 14·2%, respectively). These non-functional capillaries had open lumina and showed no sign of structural alteration, obstruction or compression, although some focal collections of myocytes (<30%) showed evidence of reperfusion damage including contraction band necrosis. Despite reductions in microvascular competence overall, coronary flow rates (non-working) did not decline, suggesting shunting via large arterio-venous channels. It seems likely that the loss of the first third of the potential for rapid functional recovery following cardioplegia is due to loss of high energy phosphates, whereas the loss of the remaining two-thirds is associated with endothelial cell mediated constriction of small arterial vessels which produces the capillary incompetence demonstrated in this study. [ABSTRACT FROM PUBLISHER]

Immigrants from the Indian subcontinent (South Asians) in England and Wales have higher morbidity and mortality from coronary heart disease than the general population; this seems to apply to both Hindus and Muslims. Studies in north west London and Trinidad found that the increased risk of coronary heart disease in Indians was not explained by dietary fat intakes, smoking, blood pressure, or plasma lipids. In the present study the distribution of coronary risk factors was measured in an East London borough where the mortality and attack rate from coronary heart disease are higher in the Asian population, predominantly Muslims from Bangladesh, than in the rest of the population. In a sample of 253 men and women aged 35-69 from general practice, mean plasma cholesterol concentrations were lower in Bangladeshi than in European men and women. Mean systolic blood pressures were 10 mm Hg lower in Bangladeshis. Plasma fibrinogen concentrations were similar in Bangladeshis and Europeans and factor VII coagulant activity was lower in Bangladeshi than in European men. In contrast with the findings in Hindus in north west London, smoking rates were high in Bangladeshi men and the ratio of polyunsaturated fatty acids to saturated fatty acids in plasma lipids was lower in Bangladeshis than in Europeans. Diabetes was three times more common in Bangladeshis than in Europeans and serum insulin concentrations measured after a glucose load were twice as high in Bangladeshis. High insulin concentrations in Bangladeshis were associated with high plasma triglyceride and low high-density lipoprotein cholesterol concentrations. Insulin resistance, leading to diabetes, hyperinsulinaemia, and secondary lipoprotein disturbances, is a possible mechanism for the high rates of coronary heart disease in South Asians in Britain and overseas. [ABSTRACT FROM PUBLISHER]

This study compared colonoscopic findings in families meeting the Amsterdam criteria (A) for hereditary non-polyposis colorectal cancer (HNPCC) but stratified according to whether the familial cancers showed DNA microsatellite instability. DNA was extracted from paired samples of normal and cancer, and microsatellite instability was analysed at up to six loci. Families were termed replication error positive (RER) when at least 50% of tumours tested per family were positive. Of 26 families studied 17 were RER and 9 were RER. Cancers in the A/RER families showed no right-sided predilection ( P<0.001). Colonoscopies have been performed on 182 at-risk members of A/RER families and 60 members of A/RER families. More of the at-risk members of A/RER families were found to have adenomas at colonoscopy ( P=0.095), but these were smaller than those of A/RER families ( P=0.19). The adenoma:carcinoma ratio was twice as high in A/RER families (13∶1) as in A/RER families (7∶1). One of the A/RER families had hyperplastic polyposis. The others do not appear to have attenuated familial adenomatous polyposis and are similar to the adenoma families or late-onset colorectal cancer families described by others. This study illustrates the importance of molecular technology in separating HNPCC from syndromes with overlapping phenotypes. [ABSTRACT FROM AUTHOR]

Shows that crystal twinning can stabilize a crystal polymorph that is otherwise not the most stable form. Use of electron microscopy, X-ray diffraction and Raman spectroscopy; Stabilization of crystal phases with useful properties by controlling twinning.