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Biomedical subjects

J R Turtle

Publications and source records attributed to J R Turtle.

At least 145 records · Page 8Linked to original sources
PubMed1978

Stimulation of protein synthesis in isolated hepatocytes by somatomedin.

Insulin (1 mU/ml) stimulated the incorporation of 14C-leucine into trichloroacetic acid-precipitable material by isolated hepatocytes from normal and hypophysectomized adult rats and 12-day-old rabbits. Somatomedin (200 ng/ml) purified from human plasma had an insulinlike effect in hepatocytes from hypophysectomized rats and baby rabbits but not from normal rats. This study suggests that, as well as being a site of somatomedin synthesis, the liver may be a target organ for this hormone.

Animals↗
PubMed1978

C-peptide secretion and insulin antibodies as determinants of stability in diabetes mellitus.

The relative significance of residual beta-cell secretory activity and human insulin antibodies in determining diabetic stability has been examined in 35 diabetic subjects. The response of plasma C-peptide immunoreactivity following 50 g oral glucose has been used as an index of beta-cell function. Glucose-stimulated C-peptide secretion was observed in 58% of stable diabetics, but in no labile diabetics. When present, C-peptide secretion following a glucose load in diabetics was of smaller amplitude and slower in onset, but more prolonged than in normal subjects. In secretors, stability of diabetes was significantly correlated with the magnitude of the C-peptide response. As a group, labile diabetics had lower insulin antibody levels than stable patients, but stability and antibody levels were not correlated in individual patients. In non-secretors there was no difference in antibody levels between the stable and labile groups. Neither the equilibrium binding affinities nor the dissociation rate constants differed significantly for antibodies from stable and labile diabetics. Thus stability of diabetes depends upon residual beta-cell secretory activity, but not on the concentration or binding characteristics of insulin antibodies.

Adolescent↗
PubMed1978

Plasma gonadotrophins and LHRH infusions in anorexia nervosa.

Nine female patients with anorexia nervosa were studied, three of them at different stages of weight gain. Basal plasma LH (luteinising hormone) was depressed in emaciated patients, but basal plasma FSH (follicle stimulating hormone) was normal. LH was significantly lower in patients who had been amenorrhoeic for less than 24 months than in those whose amenorrhoea was of longer duration. LH and FSH levels were stimulated by LHRH (luteinizing hormone releasing hormone), infused at a rate of 0.5 microgram/min for four hours. One patient, tested at 60% of standard weight, had no LH response. In all other patients below 70% of standard, the maximal LH response occurred within the first hour of infusion. In patients at higher weights, the LH response was biphasic, and the maximal level was reached during the last hour of the infusion. The FSH response, similarly, approached maximal during the first hour in patients below 70% of standard, but continued to rise throughout the infusion in patients at higher weights. Body weight expressed as a percentage of standard correlated significantly with both phases of the LH response, but not with the FSH response. Most previous authors have found an association between low body weight and depressed pituitary gonadotrophins in anorexia nervosa. The present findings further elucidate this relationship.

Adolescent↗
PubMed1978

Colonic and oesophageal disturbance in a patient with multiple endocrine neoplasia, type 2b.

We report the illness of a 32-year-old male with the syndrome of multiple endocrine neoplasia, type 2b, which comprises medullary carcinoma of the thyroid, phaeochromocytoma, oral mucosal neuromas and skeletal deformity. The patient also had evidence of ganglioneuromatosis of the alimentary tract, a finding which is held to be responsible for constipation and a number of the other gastrointestinal manifestations of the MEN, 2b. Dysphagia, which has not been previously reported in the syndrome was also present. Investigations of the oesophagus which included endoscopy, radiology and a motility study support the diagnosis of achalasia as the cause of the dysphagia.

Adrenal Gland Neoplasms↗
PubMed1977

Insulin resistance and new insulins.

Insulin therapy is required in the treatment of diabetic patients manifesting persistent ketosis. Although most patients in this category are young, many elderly diabetics fall into this group. In patients without ketosis, the indications for insulin therapy are less easy to define. In general, insulin is required if blood glucose levels cannot be maintained below 200mg/100ml following adequate diet, attainment of ideal body weight, and oral hypoglycaemic therapy.

Diabetes Mellitus↗
PubMed1976

The dissociation of insulin from human insulin antibodies.

The dissociation of insulin from human insulin antibodies has been investigated using a technique that is rapid and does not require addition of excess unlabelled insulin. A slow (k1 = 2-10(-3) min-1) and a fast k2 = 4-10(-2) min-1) dissociating antibody component were identified in all studies. These have been shown to correspond, respectively, to the high and low affinity antibody components of equilibrium binding studies. The range of k1 and k2 values and their response to temperature change is small. Insulin resistance and stability of diabetes are not related to properties of antibody dissociation. Dissociation is faster in the presence of high (6-850 nM) insulin concentration due to increased binding to the fast dissociating component without change in the dissociation rate constants. When incubation time is increased beyond achievement of maximal binding there is a time-depent rise in binding to the slow dissociating component, with a concomitant fall in k1. The traditional concept that equilibrium is established at maximum binding requires further examination.

Antigen-Antibody Reactions↗
PubMed1976

Obesity.

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Adult↗
PubMed1976

Plasma lipoproteins in pregnancy.

Plasma cholesterol, triglyceride and apolipoprotein B were measured in healthy women during pregnancy. Hyperlipidaemia was most marked in the third trimester of pregnancy, but the increases in cholesterol, triglyceride and apolipoprotein-B were not identical (14, 74 and 36%, respectively). The increase in plasma cholesterol was due to a progressive rise in very low density (VLDL) and low density (LDL) lipoproteins. There was a change in composition and size of both VLDL and LDL, demonstrated by a reduction in the ratio of cholesterol to apolipoprotein-B and altered properties of both lipoproteins on polyacrylamide gradient gel electrophoresis. It is difficult to explain these changes but they did not appear to be related to growth hormone, oestrogens or progestogens.

Acromegaly↗
PubMed1976

The thyrotrophin receptor in human thyroid plasma membranes: effect of serum immunoglobulins.

A homologous receptor assay system using human thyroid membranes and 125I-labelled human TSH (hTSH) was used to study the effect of serum and serum fractions on the binding of [125I]hTSH to the membranes. Scatchard analysis showed a single population of binding sites for TSH. Gamma globulin fractions prepared from sera of patients with Graves' disease were able to displace [125I]hTSH from the membrane to a greater extent than normal gamma globulin in 21 out of 45 cases. Increased displacement activity was seen in patients with thyroiditis, hot nodules and euthyroid eye disease but not in patients with toxic multinodular goitres. Further fractionation of the gamma globulin fraction showed that the stimulatory activity was not confined to the IgG fraction. Scatchard plots showed gamma globulin fractions decreased the number of receptor sites available for TSH binding but did not alter the affinity of the receptor for TSH. IgG fractions showed different slopes and intercepts and appeared to decrease the affinity of the receptor for TSH. LATS activity in human serum may be explained on the basis of these observations on the properties of the TSH receptor.

Binding, Competitive↗
PubMed1976

Equilibrium binding studies of insulin antibodies in diabetic subjects.

Equilibrium binding of insulin to human insulin antibodies from diabetic subjects has been studied by two methods. Results obtained by using a nondissociating gel filtration assay differed from those obtained by a conventional competitive binding method. Both methods yield data consistent with two classes of insulin binding site, having association constants of approximately 10(9) and 10(7) liter/mol. The principal differences are the higher association constant and lower number of binding sites for the high-affinity binding component, observed with the gel filtration method. In the conventional competitive binding assay, damaged radioligand, dissociation of the binding complex, or limitations of ligand availability may be responsible for the erroneous results. Data from nine diabetic patients indicate that insulin resistance and stability of diabetes cannot be explained by the binding properties of insulin antibodies alone.

Binding Sites↗
PubMed1975

Type V hyperlipoproteinaemia re-visted: findings in a sydney population.

The clinical and biochemical features of eleven patients with Type V hyperlipoproteinaemia have been reviewed. All patients were male, and there was a high incidence in the group of obesity, vascular disease, acute abdominal pain, gout, diabetes mellitus and alcoholism. Plasma cholesterol concentrations ranged from 212 to 1512 mg/100ml and triglycerides from 708 to 7670 mg/100 ml. Lipaemia was associated with significant hyponatraemia, and also interfered with the determination of plasma glucose and serum amylase. Chylomicronaemia and hyperprebetalipoproteinaemia were accompanied by reduction in the pools of beta and alpha lipoproteins. All lipoprotein classes were relatively depleted of cholesterol compared to triglyceride. There was a variable pattern of treatment response. In some patients alcohol withdrawal produced a rapid improvement in plasma lipids. In diabetes mellitus there were two types of response: a rapid one in chronic insulin deficiency, and secondly, a more gradual one in mild diabetes associated with hyperinsulinaemia. In other patients there was a rapid response to carbohydrate-calorie restriction but the respective contributions of each of the steps remained unclear.

Adult↗
PubMed1975

Antigenicity of "monocomponent" pork insulin in diabetic subjects.

"Single-peak," "single-component," and "monocomponent" insulins have been produced in an attempt to eliminate insulin antigenicity. Recently "single-peak insulin" has been shown to be antigenic. From animal experiments and preliminary human studies it has been claimed that monocomponent (MC) insulin is nonantigenic or only negligibly so. In this study the antigenicity of MC insulin was determined in two groups of diabetic patients. In group 1, seven patients treated with insulin for the first time were given MC insulin for seven to fifteen months. Four of the seven patients developed significant IgG insulin antibodies after four to ten months. In one patient the IgG insulin antibody concentration was high (8.51 mU./ml.). In two patients, IgG proinsulin-specific antibodies were detected. In group 2, fourteen patients with unstable diabetes, insulin allergy, or resistance were changed from conventional to MC insulin. Treatment with MC insulin did not decrease insulin requirement or improve diabetic control when assayed by the M factor. After seven to eleven months of therapy there was no significant fall in insulin antibodies except in two patients in whom corticosteroids had been administered simultaneously. These results differ significantly from those previously reported and could be interpreted as suggesting that insulin itself is antigenic. When the purity of the MC insulin was determined, significant contaminants could be demonstrated in all of ten separate batches of MC insulin. Gel chromatography, polyacrylamide gel electrophoresis, and proinsulin radioimmunoassay were used to identify the presence of nonconvertible insulin dimer, proinsulin, and monodesamido insulin in antigenically significant concentrations. The generation of IgG insulin antibodies in MC-insulin-treated patients cannot be interpreted as a true indication that insulin itself is antigenic. The problem of insulin antigenicity has not been resolved and will not be until a highly purified insulin is available. Unfortunately, the MC insulins do not meet these requirements.

Adolescent↗