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Biomedical subjects

C M Asplin

Publications and source records attributed to C M Asplin.

At least 37 records · Page 2Linked to original sources
PubMed1982

Glucose modulation of insulin and glucagon secretion in nondiabetic and diabetic man.

To ascertain whether the ability of glucose to influence the pancreatic islets response to a nonglucose stimulus is normal in type II diabetics, we have evaluated the modulating effect (Md) of the plasma glucose level (PG) on the acute insulin response (IRI) and glucagon response (IRG) to intravenous arginine in noninsulin-dependent diabetics (NIDDM) and nondiabetics (ND). MdIRI or MdIRG is the change in the hormonal response to arginine resulting from changes in plasma glucose level divided by the change in plasma glucose. Md has been determined over two ranges of PG: between normal fasting PG (level I) and mild hyperglycemia (approximately 160 mg/dl, level II) and between mild hyperglycemia and marked hyperglycemia (approximately 350 mg/dl, level III). Increases in PG augmented the IRI response in both groups, but the degree of augmentation was impaired in the NIDDM group. MDIRI for ND and NIDDM between levels I and II were 20 +/- 3 and 1.9 +/- 0.6, respectively, and between levels II and III were 23 +/- 5 and 2.3 +/- 0.5, respectively (P less than 0.01). MdIRI correlated with fasting PG in ND and NIDDM. Changes in PG resulted in equivalent changes in the IRG response to arginine in both groups. MdIRG for level I to II was -6.2 +/- 1.0 and -6.0 +/- 1.2, and for level II and III was -0.9 +/- 0.4 and -1.2 +/- 0.5 in ND and NIDDM, respectively. The impairment of MDIRI and its relationship to fasting PG in NIDDM support the hypothesis that fasting hyperglycemia may be, in part, a compensatory mechanism for maintaining beta-cell response to nonglucose stimuli, thereby maintaining basal insulin levels. MdIRG was normal in NIDDM when evaluated at comparable glucose levels in the ND and NIDDM groups.

Adult↗
PubMed1981

In vivo inhibition of glucagon secretion by paracrine beta cell activity in man.

The close anatomical relationships betaeen pancreatic alpha and beta cells makes possible their interaction at a local (paracrine) level. To demonstrate this in vivo, we have compared the acute glucagon response to intravenous arginine in the basal state and after beta cell suppression by infusions of insulin. The plasma glucose concentration was maintained by the glucose clamp technique. In six normal weight nondiabetics, infusion of insulin at 0.2 mU/kg per min (rate 1) raised the mean +/- SEM plasma insulin levels from 10 +/- 3 to 32 +/- 4 mU/liter and at 1 mU/kg per min (rate 2) raised plasma insulin to 84 +/- 8 mU/liter. This resulted in beta cell suppression, as shown by a diminution in the acute insulin response (incremental area under the insulin response curve, 0-10 min): basal = 283 +/- 61, 199 +/- 66 (rate 1) and 143 +/- 48 mU/liter per 10 min (rate 2) and a fall in prestimulus C-peptide from 1.05 +/- 0.17 to 0.66 +/- 0.15 and to 0.44 +/- 0.15 mM/liter (all P less than 0.01). This beta cell suppression was associated with increased glucagon responses to arginine: 573 +/- 75 (basal), 829 +/- 114 (rate 1), and 994 +/- 136 ng/liter per 10 min (rate 2) and increased peak glucagon responses 181 +/- 11 (basal), 214 +/- 16 (rate 1), and 259 +/- 29 ng/liter (rate 2) (all P less than 0.01). In all subjects, there was a proportional change between the rise in he acute glucagon response to arginine and the fall in the prearginine C-peptide level. To demonstrate that augmented glucagon response was due to betw cell suppression, and not to the metabolic effect of infused insulin, similar studies were performed in C-peptide-negative-diabetics. Their acute glucagon response to arginine was inhibited by the insulin infusion: 701 +/- 112 (basal), 427 +/- 33 (rate 1), and 293 +/- 67 ng/liter per 10 min (rate 2) as was their peak glucagon response: 268 +/- 69, 170 +/- 36, and 115 +/- 33 ng/liter (all P less than 0.01). Thus, hyperinsulinemia, within the physiological range achieved by insulin infusion, inhibits beta cell secretion which, via a paracrine mechanism, potentiates glucagon secretion.

Adult↗
PubMed1980

Detection of unrecognised nocturnal hypoglycaemia in insulin-treated diabetics.

Cortisol to creatinine ratios in overnight urine samples, urinary glucose excretion, and plasma glucose concentrations were determined in 43 diabetic inpatients. All initially had normal cortisol to creatinine ratios (less than 55 x 10(-6)) and were initially treated by increasing their long-acting insulin component. Nine patients in whom this ratio became raised then had their long-acting insulin component reduced until their fasting plasma glucose concentration was 4-7 mol/l (72-126 mg/100 ml). The 34 patients who had never had a raised ratio were treated by increasing their long-acting insulin component until their fasting plasma glucose concentration was in the range 4-7 mmol/l. All the raised cortisol to creatinine ratios were clearly separate from the other values. A mean reduction in total insulin dose of 23% and in long-acting insulin dose of 53% was achieved, abolishing presumptive nocturnal hypoglycaemia by reducing the ratio to normal and dramatically improving diabetic control. Although there was no definite evidence that the patients who had raised cortisol to creatinine ratios had suffered from nocturnal hypoglycemia, these results strongly support the view that a raised ratio indicates an otherwise unrecognised episode of this condition.

Adolescent↗
PubMed1980

Comparison of glucagon responses to 2-deoxy-D-glucose and hypoglycemia in man.

2-Deoxy-D-glucose (2DG), by competitive inhibition of glucose utilization, produces a state of intracellular glucopenia with resultant activation of both the sympathetic and parasympathetic branches of the autonomic nervous system. We have investigated the relationship between the activation of the autonomic nervous system caused by this drug and glucagon secretion. Subjects experienced symptoms identical to those observed during true hypoglycemia and demonstrated a marked rise in both gastric acid secretion and urinary epinephrine excretion. Mean immunoreactive glucagon (IRG) levels rose only slightly post-2DG (maximal mean increment, 18 pg/ml). Insulin-induced hypoglycemia, although eliciting a similar increase in urinary epinephrine excretion, was followed by a severalfold increase in IRG. Thus, although hypoglycemia and 2DG induced similar discharge of the autonomic nervous system, the glucagon response to hypoglycemia was much greater. These observations provide strong evidence that marked increases in sympathetic and parasympathetic discharge in man are weak alpha-cell stimuli and further support the hypothesis that the rise in IRG that occurs during hypoglycemia is not mediated primarily via the autonomic nervous system.

Adult↗
PubMed1980

The role of insulin absorption and sensitivity in determining a diabetic's daily insulin dosage.

The change of serum free and total insulin, and of blood intermediary metabolites, growth hormone and cortisol have been determined after separate tests using 0.3 units/kg 'Actrapid MC' given by sc injection and 0.04 units/kg/h by iv infusion in 16 fasted chronic-bovine-insulin-treated diabetics. Eight of these diabetics normally received 32 units or less of conventional, mainly bovine insulin a day and the other eight 128 units or more. Paradoxically the high dose group had a greater fall (5.6 V 3.1 mmol/l; P less than 0.05) in blood glucose four h after the sc insulin injection despite similar pre-insulin values (8.2 and 6.9 mmol/l respectively). Otherwise the responses were markedly similar in the two groups to both sc and iv insulin. Thus the gross differences in daily insulin dosage could not be explained in terms of insulin absorption or sensitivity as assessed by several metabolic parameters.

Adult↗
PubMed1979

Diurnal profiles of serum insulin, C-peptide and blood intermediary metabolites in insulin treated diabetics, their relationship to the control of diabetes and the role of endogenous insulin secretion.

The 24-hour profiles of blood metabolites, serum free and total insulin, and C-peptide were measured in 16 insulin dependent diabetics, and then analysed in order to compare the effects of the presence or absence of residual endogenous insulin secretion and the presence of good or bad diabetic control as judged by the levels of blood glucose or total ketone bodies. Retention of endogenous insulin secretion, responsive to meals, and changes in the level of blood glucose and serum free insulin, were detected in nine patients, its presence having important effects in maintaining metabolic regulation closer towards normal. Despite the fact that apparently well controlled diabetics were selected for the study, the diurnal changes of the levels of blood metabolites, serum free and total insulin and their interrelationships were all grossly abnormal. The levels of both the blood total ketone bodies and the blood glucose were found to be a poor guide to the presence or absence of other metabolic abnormalities of diabetes. High levels of blood total ketone bodies appeared to have a protein sparing effect.

Adult↗
PubMed1978

Change of insulin dosage, circulating free and bound insulin and insulin antibodies on transferring diabetics from conventional to highly purified porcine insulin.

Fifty-eight patients on long term conventional mainly bovine insulins have been transferred to highly purified porcine insulin preparations. There was an overall reduction of 22% in daily insulin dosage and improved diabetic control as shown by decreased blood glucose concentration. Increased concentrations of serum free insulin and falls in serum bound insulin levels were also found. There were reductions in the serum binding capacities and affinity constants on changeover from conventional to highly purified insulin due to a combination of the effects of differential conventional/purified porcine binding and the substitution of a low antigenicity insulin. However, 12 of the patients receiving higher doses of insulin experienced marked hypoglycaemic reactions immediately on insulin changeover despite initial dosage reductions of 30% and prior to any changes in antibody characteristics.

Adolescent↗
PubMed1978

A comparison between diabetics receiving a high or low daily insulin dosage.

Two groups of 8 diabetics, similar in many aspects, who required high (greater than or equal to 128 units) or low (less than or equal to 32 units) total daily insulin dosage were compared during a 24 hour period. C-peptide secretion was detected in all but one of the low dose group, but only in two of the high dose group. No significant differences in serum free and total insulin concentrations were detected and the patterns of blood metabolites were also similar, apart from higher blood glycerol concentrations in the low dose group. No significant differences in the binding characteristics of the antiinsulin antibodies were detected.

C-Peptide↗
PubMed1978

The relationship between circulating free and bound insulin, insulin antibodies, insulin dosage and diabetic control in insulin treated diabetics.

Free and bound insulin concentrations, blood glucose and anti-insulin antibody binding characteristics have been determined in 100 insulin treated diabetics; medium serum free insulin was 11 mU/l when fasting and rose to 30 mU/l after the mid-day meal. Significant correlation between blood glucose and serum free (but not bound) insulin was found. No relationship between insulin antibodies and daily insulin dose or diabetic control were found, nor a relationship between free insulin and antibody characteristics.

Adolescent↗
PubMed1977

The measurement of serum free insulin by steady-state gel filtration.

A method for the separation of bound and free insulin in the serum of insulin treated diabetics by steady state gel filtration is described. The method meets the criteria which have been suggested for the validation of a method of separating bound from free ligand. The precision of the method is satisfactory, and the results compare well with those obtained by the methods of ethanol precipitation and polyethylene glycol precipitation.

Chromatography, Gel↗
PubMed1977

Serum free insulin concentrations during the treatment of diabetic coma and precoma with low dose intramuscular insulin.

Fifty patients in diabetic coma or precoma, 33 of whom had previously received insulin and had circulating insulin antibodies, were studied during treatment with a low-dose intramuscular insulin regime. In the presence of insulin antibodies, serum free insulin was separated from bound insulin by steady-state gel filtration. The initial mean serum free insulin concentration in the group of patients without insulin antibodies was 9 mU/1, 1 to 2 hours after intramuscular therapy it had risen to 22 mU/1, and after 7 to 8 hours to 73 mU/1. The corresponding concentrations for the group with insulin antibodies were 13, 23 and 74 mU/1. No relationship was found between the concentrations of serum free insulin attained and the age of the patients, their initial degree of acidosis, dehydration, and systolic blood pressure, the insulin antibody characteristics of their sera, nor the rate of decline of the blood glucose.

Adolescent↗
PubMed1976

Plasmapheresis in the management of acute systemic lupus erythematosus?

Eight patients with systemic lupus erythematosus (S.L.E.) have been treated with plasmapheresis. In four patients in whom immunochemical studies indicated high levels of circulating immune complexes, the removal of 5-8 litres of plasma weekly produced a striking clinical and immunochemical improvement. The four other patients, with only minor complement disturbances and no direct evidence of circulating immune complexes, could not be shown to benefit from plasmapheresis and one patient in this group died of cerebral lupus despite intensive treatment with cytotoxic drugs. It is concluded that plasmapheresis may be of value as an adjuvant to the treatment of acute S.L.E.

Acute Disease↗