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Biomedical subjects

D M Fraser

Publications and source records attributed to D M Fraser.

At least 19 recordsLinked to original sources
PubMed1992

Mediation of glycosylated and partially-deglycosylated glucose oxidase of Aspergillus niger by a ferrocene-derivatised detergent.

A ferrocene-derivatised detergent, (11-ferrocenylundecyl) trimethylammonium bromide (FTMAB), when oxidised to the corresponding ferricinium ion, was found by electrochemical studies to be an effective electron acceptor for reduced glucose oxidase of Aspergillus niger (EC 1.13.4) and thus acts as a electron-transfer mediator between glucose oxidase and a working electrode held at a potential sufficiently positive to reoxidise reduced FTMAB. An increase in mediating activity was produced when FTMAB was present in concentrations above its critical micelle concentration. An 'enzyme electrode' was formed by adsorption of glucose oxidase and FTMAB surfactant on a graphite rod. The electrode functioned as an amperometric biosensor for glucose in phosphate-buffered saline solution. A mixed micelle of glucose oxidase and FTMAB, probably adsorbed on the electrode surface, appears to be advantageous for the amperometric determination of glucose. Additionally, glucose oxidase was treated with alpha-mannosidase. When this partially-deglycosylated glucose oxidase was incorporated in an enzyme electrode, a 100-fold increase in the second-order rate constant (k) for electron transfer between the enzyme and FTMAB was observed, together with increased current densities, with respect to the equivalent values for FTMAB and commercial glucose oxidase. The use of deglycosylated enzymes in biosensors is suggested.

Aspergillus niger↗
PubMed1992

Dilated cardiomyopathy associated with chronic overuse of an adrenaline inhaler.

Endogenous catecholamines in excess are known to cause dilated cardiomyopathy. A patient presented with dilated cardiomyopathy after many years of overusing an adrenaline inhaler. Pathological features and a considerable improvement in myocardial function after withdrawal implicated the exogenous catecholamine excess in the pathogenesis of the cardiomyopathy.

Adult↗
PubMed1979

Glycosylated haemoglobin concentrations in newly diagnosed diabetics before and during treatment.

Concentrations of total glycosylated haemoglobins (Hb A1) were measured in 40 diabetics at diagnosis and at monthly intervals after treatment with chlorpropamide, insulin, or diet alone was begun. The mean Hb A1 concentration at presentation in 16 patients treated with chlorpropamide was significantly higher than that in 12 patients treated with insulin, and the duration of glycaemic symptoms was much longer in the chlorpropamide-treated group. In contrast, the mean plasma glucose concentration was similar in both groups. The mean concentrations of Hb A1 and plasma glucose at diagnosis in the 12 patients treated by diet alone were lower than those in the other two groups, and most of these patients were free of symptoms. Treatment quickly relieved symptoms and lowered plasma glucose in all patients. The Hb A1 concentration fell significantly with treatment such that after two months there was no significant difference between the three groups, although results remained above the normal range. These findings support the theory that the Hb A1 concentration reflects the blood glucose control over the previous one to two months and suggest that the duration of hyperglycaemia may be important in determining the Hb A1 concentration as well as the absolute blood glucose concentration.

Adult↗
PubMed1979

Mononeuropathy in diabetes mellitus.

Fifty-one diabetic patients with mononeuropathies wereoneuropathy were studied to examine possible etiological factors, to determine the relationship with other diabetic complications, and to correlate with the presence and severity of background peripheral and autonomic neuropathy. The median, ulnar, and lateral popliteal nerves were most commonly affected and cranial neuropathy was relatively uncommon. When bilateral involvement of the same nerve was excluded, multiple mononeuropathies were found in only five patients. Median and ulnar mononeuropathy were gradual in onset and affected the dominant limb whereas other types of mononeuropathies were acute in onset with no predilection for either side. No consistent relationship was shown between the onset of mononeuropathy and age, sex, diabetic treatment, duration of diabetes, diabetic control, or other diabetic complications. In particular, there was no significant background peripheral and autonomic neuropathy, as assessed clinically and by objective tests, in almost one-half of the patients studied. It is concluded that diabetic mononeuropathy may occur independently of peripheral and autonomic neuropathy. It is possible, however, that a minimal degree of background damage, known to be present in all diabetic patients, may render them more susceptible than the general population to the various factors causing mononeuropathy.

Abducens Nerve↗
PubMed1977

Plasma beta-thromboglobulin in diabetes mellitus.

The plasma beta-thromboglobulin (betaTG) content was measured in 56 diabetic patients with known complications of this disease, including neuropathy, retinopathy, and ischemic skin lesions. Although two patients were found to have elevated levels beyond the normal range, there was no significant difference between the diabetic group as a whole and the group of 35 controls. The significance of these findings with regard to the proposed contribution of small-vessel platelet sequestration in the pathogenesis of late complications of diabetes mellitus is discussed.

Beta-Globulins↗
PubMed1977

Peripheral and autonomic nerve function in newly diagnosed diabetes mellitus.

Peripheral and autonomic nerve function was assessed in 10 newly diagnosed male diabetics (six insulin-treated and four sulfonylurea-treated) with repeated observations over the subsequent six months. There was significant impairment of motor-conduction velocity in the common peroneal nerve at diagnosis in both treatment groups, with improvement following treatment in only the insulin-treated patients. In contrast, although the blood glucose level fell in both groups, the mean level was significantly lower in the sulfonylurea-treated patients at two months and at each subsequent visit. In the autonomic function tests significant abnormality was found in the electrocardiographic R-R-interval (beat-to-beat) variation in resting heart rate in two of the insulin-treated patients and all of the sulfonylurea-treated group, with improvement in only one of the latter. One patient in the sulfonylurea-treated group also showed an abnormal response to the Valsalva maneuver (expressed as the Valsalva ratio), and this remained abnormal throughout the period of study. All other patients had normal responses to the Valsalva maneuver and sustained handgrip test. None of the patients had postural hypotension. Abnormalities in autonomic nerve function in diabetics at diagnosis have not been previously reported.

Adolescent↗