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Biomedical subjects

T D Hockaday

Publications and source records attributed to T D Hockaday.

At least 55 records · Page 3Linked to original sources
PubMed1987

Oral glucose tolerance and ambient temperature in non-diabetic subjects.

When either a 960-kcal, 140-g carbohydrate meal, or a 75-g glucose load was ingested by non-diabetic Caucasians, the 2-h venous plasma glucose concentration was higher by 0.82 and 1.25 mmol/l, respectively, if the ambient temperature was 33 degrees C rather than 23 degrees C. It is likely that this is a result of relative 'arterialisation' of the venous blood. Even at 23 degrees C room temperature, use of the 'hot hand' technique to obtain 'arterialized' venous blood increases post-load glucose levels in contralateral antecubital veins. If these observations apply to those acclimatised to the heat, they could affect the diagnosis of both diabetes and impaired glucose tolerance in the tropics.

Adult↗
PubMed1987

The effect of oral glucose on the leucocyte sodium pump in normal and obese subjects.

The effect of oral glucose (40 g/m2 body surface area) on the leucocyte 22Na efflux rate constants (ERC) was studied in 13 normal weight and 10 obese subjects. The ouabain-sensitive 22Na ERC was higher in leucocytes isolated from fasting obese subjects (median [range] for obese 2.77 [2.33-3.11] vs normals 1.91 [1.57-2.77] h-1, P less than 0.001). There was no difference in the ouabain-resistant 22Na ERC. Oral glucose raised the ouabain-sensitive 22Na ERC after 2 h in normal subjects (1.91 [1.57-2.77] to 2.41 [2.11-3.02] h-1, P less than 0.001). The ouabain-resistant 22Na ERC fell from 0.71 [0.32-1.10] to 0.46 [0.35-0.68] h-1, P less than 0.008. Conversely, in obese subjects, the ouabain-sensitive ERC fell (2.77 [2.33-3.11] to 2.59 [2.11-2.92] h-1, P less than 0.06). There was no significant change in ouabain-resistant 22Na ERC 2 h after oral glucose. The fasting leucocyte 22Na ouabain-sensitive ERC correlated with fasting plasma insulin levels and insulin resistance (rs = 0.48, P less than 0.01 for both). The change in this ERC with oral glucose correlated with the incremental insulin response over 2 h (rs = -0.53, P less than 0.006) and to the insulin resistance (rs = -0.56, P less than 0.003). The failure of oral glucose to stimulate the leucocyte sodium pump in obesity could partially account for the defect in dietary thermogenesis in obesity. This defect in stimulation of the sodium pump is related to insulin resistance.

Adult↗
PubMed1987

High-carbohydrate and fibre diets in the treatment of diabetes.

After Kinsell and collaborators (1970) demonstrated a smaller glycaemic rise in diabetic subjects given larger rather than smaller nutrient loads (because of the more complicated composition of the intakes) notions that one can usefully prescribe diabetic diets from crude chemical composition of foods 'on the shelf' have been abandoned, with greater consideration of the varied gastro-intestinal handling of foods, how they are changed by cooking, etc., the way different food interact within the gastro-intestinal tract, and the importance of specific chemical constitution, both of the classical nutrients as well as fibre contents. In practice, high-carbohydrate diets are usually entwined with high-fibre intake. Apart from the observations on the practicability of high-carbohydrate diets in obtaining successful glycaemic control of diabetics outside the 'First World', doubts were voiced in the late 1920s concerning the wisdom of the high-fat intake accompanying low-carbohydrate diets. In the next decade Himsworth showed in normal subjects that high-carbohydrate intake improved glucose tolerance, and this has been repeated in Seattle. Data concerning complete meals or, much better, dietary regimes persisted with over long periods of time are more relevant than those from single intakes of liquid homogenates. We present observations on 6-week intakes of particular dietary regimes (in free-living patients) from which the main conclusions would seem: a high-carbohydrate intake does no harm to glycaemic control in diabetics, providing it is predominantly of polysaccharides; a high-fibre intake has various beneficial effects, and in particular high viscous fibre intake reduces post-prandial glycaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1987

Serum insulin concentrations and anticipatory factors of cardiomyopathy in NIDDM.

To summarise from some preliminary analyses, a high early insulin: obesity (BMI) ratio remains an associate of later development of ECG change in this diabetic population, and there are reasons to suggest that this may be involved particularly through mechanisms of relative insensitivity to the hypoglycaemic effect of insulin.

Adult↗
PubMed1987

Erythrocyte aldehyde dehydrogenase, plasma chlorpropamide concentrations and the chlorpropamide alcohol flush.

Erythrocyte aldehyde dehydrogenase activity (EALDH) was measured in 21 diabetics on long-term chlorpropamide therapy. Median EALDH was 0.362 units, range 0.108 to 0.750 units and correlated neither with previously assessed chlorpropamide alcohol flushing nor with coincident plasma or erythrocyte chlorpropamide concentration. The hypothesis that genetic or permanently acquired reduction in EALDH correlates with CPAF status was not supported. There was no concentration-related inhibition of the enzyme by prevailing plasma or erythrocyte chlorpropamide.

Alcohol Drinking↗
PubMed1986

Diabetic retinopathy: different risk factors for exudates and haemorrhages.

The retinae of 137 patients were examined ophthalmologically and for visual acuity at diagnosis of non-insulin dependent diabetes and again in 1982 and 1983, approximately 7 and 8 years later, when colour photographs were also taken. In 1983, 46% were without detectable retinopathy, 32% had haemorrhages (including microaneurysms) only, 4% exudates alone and 18% both lesions. Those with haemorrhages were more hyperglycaemic than those without retinopathy and those with exudates only. Indeed, those with exudates alone had lower mean glucose levels than those without retinopathy (p less than 0.05). Patients with exudates (+/- haemorrhages) had a lower percentage of the fatty acids of plasma cholesterol esters as linoleate than those without (p less than 0.05) but this did not hold for those developing haemorrhages. Different risk factors appear to operate in different features of diabetic retinopathy. In some respects exudate formation may be more akin to macro than to micro angiopathy.

Aged↗
PubMed1986

Non-esterified fatty acids may regulate human leucocyte sodium pump activity.

Human leucocyte sodium pump activity was studied in normal fasting subjects by measuring the ouabain-sensitive 22Na+ efflux rate constants. This 22Na+ efflux rate constant was inversely related to the fasting plasma non-esterified fatty acid level (rs = -0.73, P less than 0.0001). An oral glucose load (40 g/m2 surface area) led to an increase in the leucocyte ouabain-sensitive 22Na+ efflux rate constant after 2 h (1.97 +/- 0.25 to 2.44 +/- 0.19 h-1, P less than 0.0001, n = 11). There was a concomitant fall in the plasma non-esterified fatty acid level. Incubation of leucocytes in vitro with 100 mumol/l linoleic acid inhibited the leucocyte ouabain-sensitive 22Na+ efflux rate constant (1.52 +/- 0.27 vs 0.84 +/- 0.24 h-1, P less than 0.001, n = 8). The leucocyte Na+,K+-dependent adenosine triphosphatase (Na+,K+-ATPase) activity was inhibited in vitro by long chain non-esterified fatty acids, especially when unsaturated. Non-esterified fatty acids may account for some of the Na+,K+-ATPase inhibitory activity of plasma.

Biological Transport, Active↗
PubMed1986

The leucocyte sodium pump in healthy and obese subjects: the association of insulin with its activity.

Leucocyte ouabain-sensitive 22Na+ efflux was studied in 35 normal and 12 obese subjects. This efflux rate constant was raised in the obese (2.72 +/- SEM 0.13 vs 2.31 +/- 0.08 h-1, P less than 0.006), indicating a higher activity of the sodium pump in vivo, There was a significant correlation between this efflux rate constant and fasting insulin level in both the whole population and in the normals alone (rs = 0.36, P less than 0.007, and rs = 0.40, P less than 0.009 respectively). A hyperinsulinaemic-euglycaemic clamp was performed on seven normal volunteers. After 2 h, there was a significant stimulation of the leucocyte efflux rate constant (from 2.86 +/- 0.17 to 3.33 +/- 0.18 h-1, P less than 0.01). In-vitro incubation of leucocytes with insulin produced a maximal stimulation of the Na+-K+-ATPase activity of about 35% at 2 h with half-maximal stimulation achieved at 46 mU/l. Insulin (100 mU/l) also stimulated the leucocyte ouabain-sensitive 22Na+ efflux rate constant in vitro by about 11% with or without 1 h of preincubation with the insulin. These findings may explain the hypokalaemic and sodium retaining effects of insulin in man; they may also partially explain the raised Na+ efflux rate constants in obesity.

Adolescent↗
PubMed1986

Acceptability of high-fibre diets in diabetic patients.

Twenty-five diabetic patients were selected from Oxford Diabetic Clinics to assess their dietary compliance (Group A). All had been taught to follow diets rich in dietary fibre in which carbohydrate provided 50% of total energy. The results were compared with those obtained previously from a similar group of patients (Group B) all of whom had been instructed to follow a diet in which carbohydrate provided 40% of total energy. The patients of Group A had a significantly greater intake of carbohydrate (45.1% vs 34.7% of total energy) and dietary fibre (33.1 g vs 18.7 g) and a lower intake of fat (33.5% vs 42.1% of total energy) than the patients of Group B. The results of dietary assessment obtained from a third group of patients (Group C), who had been advised to follow a high-fibre diet before the widespread availability of dietary teaching aids and recipe books, showed that carbohydrate and fat provided 37.5% and 41.0% of total energy, with a dietary fibre intake of 25.6 g. The results suggest that patients are willing and able to change their dietary habits towards a distribution of food constituents likely to improve diabetic control and reduce the risk of coronary heart disease when given enthusiastic instruction and support in diabetic clinics.

Adult↗
PubMed1986

High levels of growth hormone and human placental lactogen in pregnancy complicated by diabetes.

The possible involvement of growth hormone (GH) and human placental lactogen (HPL) in the development of diabetic tissue damage during pregnancy was studied in 16 insulin-dependent diabetic patients (IDDM), 8 gestational diabetic patients (GD) and 14 normal pregnant women. GH and HPL were elevated in pregnancies complicated by diabetes but, in contrast to the rise of HPL, GH declined throughout pregnancy in all the groups studied. The concentrations of neither correlated with plasma glucose, insulin requirement or duration of diabetes. HPL was positively correlated with urinary albumin excretion (UAE) in all 3 groups, but with blood pressure only in the IDDM group. There was also a significant and positive correlation in all patients between HPL at the end of pregnancy and placental weight. No evidence of serious tissue damage was found in either diabetic group. The vibration sensory threshold was unaffected by pregnancy and was similar to that of normal women. However, in the IDDM group UAE increased significantly postpartum when compared with second trimester values; they also had higher UAE than the other 2 groups post-delivery. A small but significant rise in diastolic blood pressure (DBP) was found in the 3 groups studied between the second and third trimester and pre-delivery. The same trend in systolic blood pressure (SBP) was seen in the diabetic groups. The IDDM had higher systolic and diastolic blood pressures than the normal women at all stages of gestation.

Adult↗
PubMed1985

Delayed diagnosis of non-insulin-dependent diabetes is associated with greater metabolic and clinical abnormality.

Seventy-seven per cent of 235 newly diagnosed and untreated patients with diabetes mellitus were polysymptomatic at their first visit to hospital. The larger the number of typical symptoms, the greater was the duration of the longest lasting one (p less than 0.001). Symptom duration was positively correlated with pre-treatment fasting plasma glucose (p less than 0.05), but this was more strongly linked to the number of symptoms (p less than 0.001). In those patients diagnosed because of symptoms typical of diabetes mellitus, mean fasting glucose was higher than when symptoms were elicited retrospectively in patients in whom glycosuria had been found unexpectedly. Weight loss at diagnosis (from 'highest remembered') was positively correlated with fasting plasma glucose (p less than 0.001). One hundred and thirty-two patients had fundal colour photography 7 or 8 years after diagnosis. The mean pre-diagnosis duration of symptoms was 2 +/- S.D.17 months in 80 without retinopathy compared to 8 +/- 6 months for 52 with retinopathy (p less than 0.001). The severity of retinopathy was also positively associated with symptom duration, as was failure to attend for these ocular reviews. Prolonged symptoms pre-diagnosis were associated with increased risk of death during the first 5 years post-diagnosis among those with a normal electrocardiogram (ECG) initially (p less than 0.003), but was unrelated to ECG abnormality then or during the next 5 years. These findings accord with (but offer no proof of) the inherently plausible expectation that both morbidity and mortality would be lessened by earlier diagnosis of non-insulin-dependent diabetes mellitus.

Adult↗