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Biomedical subjects

T J Lyons

Publications and source records attributed to T J Lyons.

104 records · Page 6Linked to original sources
PubMed1986

Familial hypocalciuric hypercalcaemia as a differential diagnosis of hyperparathyroidism: studies in a large kindred and a review of surgical experience in the condition.

We have studied 46 members of a large kindred with familial hypocalciuric hypercalcaemia (FHH) after a neck exploration failed to cure hypercalcaemia in an asymptomatic patient. Serum calcium, serum phosphate, plasma parathormone and vitamin D metabolites do not distinguish affected members from patients with hyperparathyroidism. Because of the continuing debate as to whether or not FHH is a variant of, or distinct from, hyperparathyroidism, we have carried out a review of surgical experience with subtotal parathyroidectomy in hyperparathyroidism secondary to parathyroid hyperplasia and in FHH. Whereas the procedure is successful in 90 per cent of the former cases only one case of FHH has been cured by it. This provides evidence for the two conditions being aetiologically distinct. Before patients with asymptomatic hypercalcaemia are referred for parathyroid surgery the calcium:creatinine clearance ratio should be measured using a 2 h urine sample collected after an overnight fast and a fasting blood sample. If this ratio is less than 0.01 then screening of first degree relations should be undertaken before any parathyroid surgery is performed. Unnecessary surgery can therefore be avoided.

Adult↗
PubMed1986

Glycosylation of low density lipoprotein in patients with type 1 (insulin-dependent) diabetes: correlations with other parameters of glycaemic control.

Glycosylation of low density lipoproteins obtained from 16 patients with Type 1 (insulin-dependent) diabetes and from 16 age-, sex-, and race-matched controls, was determined. The diabetic patients were normolipaemic and were in good or fair glycaemic control. Eleven patients performed home blood glucose monitoring. Glycosylation of low density lipoproteins in the diabetic patients was significantly higher (p less than 0.001) than in the control subjects, and was significantly correlated with haemoglobin A1c, (p less than 0.01), glycosylation of plasma proteins, (p less than 0.001), and mean home blood glucose, (p less than 0.01). This study confirms that, in diabetic patients, increased glycosylation of low density lipoprotein occurs to an extent which correlates closely with other commonly used indices of glycaemic control.

Adult↗
PubMed1986

Temporal relationship between the onset of daily gonadotrophin surges and of puberty in female golden hamsters.

Daily rhythms of LH and FSH release commence on day 16 or 17 of age in the prepubertal female golden hamster, 2-3 weeks before regular 4-day oestrous cycles begin. We tested the hypothesis that the daily surges of gonadotrophin regulate, at least in part, rate of sexual maturation and, hence, age at puberty. We predict that an advance or a delay in the initiation of the daily rhythm should result in a corresponding advance or delay in the day of puberty. In the first test, the onset of daily gonadotrophin surges was advanced by gonadotrophin-releasing hormone (GnRH) injections; in the second test, the onset was delayed by daily injection of phenobarbital sodium (PB). The day of the first of at least three consecutive post-ovulatory vaginal discharges was used as an index of the age at puberty. Gonadotrophin-releasing hormone (50 ng/0.1 ml saline per animal) was injected at 16.30 h on days 8-17 of age. These injections initiated a daily mid-afternoon surge of LH about 8 days before the onset of the daily rhythm of gonadotrophins in saline-injected controls and the day of first vaginal discharge was advanced by 4 days compared with saline-injected controls (32.0 +/- 1.8 days vs 36.3 +/- 1.0 days; P less than 0.001). Phenobarbital sodium (100 mg/kg body wt), injected at 13.30 h from 16 to 25 days of age, blocked daily surges of gonadotrophin observed in controls by day 18.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Non-enzymatic glycosylation of skin collagen in patients with type 1 (insulin-dependent) diabetes mellitus and limited joint mobility.

Forearm skin biopsies were obtained from diabetic subjects with and without limited joint mobility, and from non-diabetic control subjects. Collagen purified from these samples was assayed for non-enzymatic glycosylation. The level in all diabetic patients was significantly greater than that in control subjects (p less than 0.001), but those diabetic patients with limited joint mobility had a level of collagen glycosylation similar to that in those with normal joints (15.3 +/- 1.3 and 16.5 +/- 1.3 nmol fructose/10 mg protein, respectively; mean +/- SEM). Glycosylation of collagen in the diabetic patients correlated with glycosylated haemoglobin measured at the time of skin biopsy (r = 0.60). These results do not support the hypothesis that non-enzymatic glycosylation of collagen, as reflected by the ketoamine link, plays an important role in the development of limited joint mobility in diabetes.

Adult↗
PubMed1985

Effect of in vitro non-enzymatic glycosylation of human skin collagen on susceptibility to collagenase digestion.

The effect of glycosylation on susceptibility of skin collagen to collagenase digestion was studied in a skin sample obtained at autopsy from the interscapular region of a 24 year old white male who had died of an acute illness and who had no history of diabetes. Homogeneous suspensions of insoluble collagen were prepared, and were incubated in 50 mmol l-1 dextrose at pH 7.35 and 37 degrees C for 7 days. Non-enzymatic glycosylation measured by the weak acid hydrolysis/thiobarbituric acid method increased from 13.1 +/- 1.0 (n = 5) to 45.2 +/- 5.5 (n = 8) nmol fructose per 10 mg collagen (P less than 0.001). Digestion of collagen using clostridial collagenase was monitored by measuring (a) hydroxyproline content and (b) absorption at 206 nm of the supernatant after centrifugation to remove substrate. The rate of digestion was similar in glycosylated and control collagen. We conclude that the ketoamine link formed in non-enzymatic glycosylation does not increase the resistance of collagen to enzymatic digestion. The possibility remains that subsequent rearrangement of this link could be important in this respect.

Adult↗
PubMed1985

Effect of acarbose on biochemical responses and clinical symptoms in dumping syndrome.

A dose of 50 mg of acarbose was administered with a standard breakfast to 13 subjects with dumping syndrome. Significant attenuation of hyperglycaemia (p less than 0.01) was observed, and rises in plasma gastric inhibitory polypeptide, insulin and enteroglycagon were reduced (p less than 0.05). Plasma levels of neurotensin, vasoactive intestinal polypeptide and somatostatin were not affected. Dumping score was reduced, but this did not achieve statistical significance. In a longer-term study, 9 patients took acarbose, 50 mg t.i.d., for 1 month. No significant reduction in the number or severity of dumping attacks was observed, but a majority expressed a preference for the drug and some individuals experienced a marked improvement of symptoms.

Acarbose↗
PubMed1984

Predicting the need for insulin therapy in late onset (40-69 years) diabetes mellitus.

A six-year prospective study of 144 newly diagnosed, symptomatic diabetic patients aged 40-69 years showed that 21 (15%) required insulin therapy, commencing 1-61 months after diagnosis. The plasma insulin response to oral glucose was assessed at the time of diagnosis. All 12 patients with very low peak insulin response (less than or equal to 6 mU/l) required insulin therapy. Thirty-six patients had an intermediate insulin response (greater than 6 less than or equal to 18 mU/l); of these, 7 with a mean weight 88% (range 73-96%) of average body weight required insulin, while 29 with a mean weight 117% (range 98-158%) of average body weight, did not. Ninety-six patients had a peak insulin response (greater than 18 mU/l); 2 patients whose weights were 96% and 100% of average body weight, required insulin, while the remainder did not. Consideration of initial body weight and peak insulin response provides a useful prediction of the eventual need for insulin.

Adult↗
PubMed1982

Parotid tumours.

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Adenoma↗