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Biomedical subjects

A J Hudson

Publications and source records attributed to A J Hudson.

At least 73 records · Page 4Linked to original sources
PubMed1982

Monocyte IgG-Fc receptors in myotonic dystrophy.

Myotonic dystrophy (MyD), an autosomal dominant neuromuscular disease with multisystem abnormalities, is associated with hypercatabolism of IgG. The hypercatabolism is not related to structural abnormalities of the IgG molecule in MyD but appears to be due to a derangement of the serum IgG concentration-fractional catabolic rate relationship. Since the catabolic pattern of IgG is governed by the Fc portion of the molecule, the possibility of Fc receptor dysfunction in MyD has been explored. We have observed that although MyD patients have normal numbers of Fc receptor bearing leucocytes in their peripheral blood, MyD monocytes express significantly (P less than 0.02) greater numbers of Fc receptors (47.9 +/- 21.2 X 10(3) receptors/monocyte) than do monocytes of healthy subjects (29.1 +/- 9.6 X 10(3) receptors/monocyte). The mean affinity constants of the Fc receptors was lower in the MyD group (1.5 +/- 0.7 X 10(8)/M) than the normal control group (2.4 +/- 0.9 X 10(8)/M) but this difference was not statistically significant. MyD monocytes showed a propensity to shed Fc receptors in culture at 37 degrees C whereas no significant shedding was observed with control monocytes. Thus MyD monocytes may shed Fc receptors at physiological temperatures but at the same time express more receptors per cell than normal monocytes. This suggests that MyD monocytes may have an abnormally high turn-over of Fc receptors.

Cells, Cultured↗
PubMed1981

Glucose transport and oxidation in adipose tissue of patients with myotonic dystrophy.

The effect of insulin on the transport of 2-deoxyglucose and the oxidation of glucose in chopped adipose tissue was investigated in 14 myotonic dystrophy (MyD) patients and 28 age and size-matched control subjects. The transport of 0.55 mM 2-deoxyglucose was measured over 3 min at 37 degrees C both with and without 32 ng/ml of insulin. Oxidation was determined at 37 degrees C for 90 min by the measurement of 14CO2 released from a system containing 0.55 mM glucose with and without 50 ng/ml of insulin. Basal 2-deoxyglucose transport was not reduced in MyD subjects but insulin-stimulated 2-deoxyglucose transport in MyD was significantly less at 0.512 +/- 0.220 nmole compared to control subjects with 0.906 +/- 0.160 nmole/100 mg tissue/3 min (P less than 0.02). Both the basal and insulin-stimulated glucose oxidation were significantly less in the MyD group. Insulin-stimulated oxidation was 2.92 +/- 0.21 nmole in the control subjects compared to 2.20 +/- 0.27 nmole/100 mg tissue/90 min in the MyD cases (P less than 0.02). Similar findings were obtained when calculations were based on nmoles of 2-deoxyglucose transport and glucose oxidation/100 mg lipid. The findings indicate that both glucose transport and oxidation are impaired in MyD.

Adipose Tissue↗
PubMed1978

The muscular pain-fasciculation syndrome.

Five cases of a chronic neuromuscular syndrome consisted of muscular aching and sometimes burning pain, fasciculations, cramps, fatigue, and occasional paresthesia. The disorder affected the legs and, less commonly, the girdle, trunk, and arm muscles. The symptoms were enhanced by physical activity and were usually improved by rest. Neither muscular wasting nor weakness was found, although the condition was present for an average of 4.7 years and, in one patient, as long as 10 years. Electrophysiologic studies showed motor abnormalities indicative of axonal degeneration and muscle fiber denervation, most marked in the legs. Light microscopy of skeletal muscle and spinal cord in one case disclosed evidence of mild denervation atrophy in muscle, but no loss of anterior horn cells. The findings are compatible with a benign polyneuropathy.

Adult↗
PubMed1977

Carbohydrate metabolism and insulin resistance in myotonia dystrophica.

Carbohydrate metabolism was studied in fourteen patients with myotonia dystrophica (MD) using oral glucose, fructose and galactose tolerance tests. Insulin responses to tolbutamide, glucagon, arginine and leucine were determined and insulin resistance was measured with exogenous iv insulin. Glucose tolerance was impaired in twelve of the four teen subjects while hyperinsulinism was found in all patients studied. Insulin response to the various substances was excessive. The insulin tolerance test revealed insulin resistance in all patients and this generally correlated well with the degree of hyperinsulinism to provocative tests. Serum galactose levels after an oral load were much lower in MD compared to normal subjects and were associated with a correspondingly greater rise in glucose, indicating an increased conversion of galactose to glucose. A similar response to oral galactose was found in diabetics. The hyperinsulinism seen with the fructose and galactose tests corresponded well to the rise in glucose during the test. Urinary sorbitol excretion was normal. It is concluded that the impaired carbohydrate metabolism seen in MD is due to peripheral insulin resistance affecting various organs including the liver and it is suggested that the excessive beta-cell response is secondayr to the peripheral resistance.

Adult↗
PubMed1976

Adenyl cyclase and cyclic nucleotide phosphodiesterase activities in murine muscular dystrophy.

Adenyl cyclase and cyclic nucleotide phosphodiesterase activities were assayed in homogenates of hind leg skeletal muscle from dystrophic and normal mice. Adenyl cyclase activity was stimulated 2.5 times by epinephrine and 6 times by fluoride over the basal activity in both dystrophic and normal mice. The activity of adenyl cyclase from dystrophic muscle of mice was significantly higher than that of normal mice under all the conditions tested (i.e. basal, epinephrine and fluoride). Cyclic nucleotide phosphodiesterase from skeletal muscle of mice has two Km's (2.1 and 11 mumol/l) which suggests the existence of either two forms of enzyme or a single enzyme with negative cooperativity. The activity of this enzyme was significantly elevated in the skeletal muscle of dystrophic mice compared to the normal controls. The available evidence suggests that the same cyclic nucleotide phosphodiesterase is responsible for the hydrolysis of both cyclic AMP and cyclic GMP.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1975

Comparison of the intermediary metabolism of fatty acids in denervated and dystrophic murine skeletal muscle.

Certain aspects of lipid metabolism have been examined in denervated muscle from normal mice and in dystrophic muscle from mice of the Bar Harbor strain 129. A number of parameters show no change or similar changes. For example, the utilization of palmitate-[1-14C] and palmitylcarnitine by mitochondria from denervated and dystrophic hind leg skeletal muscle showed parallel decreased in the oxidation of palmitate (30-42%) and palmitylcarnite (37-66%). A comparable study with acetylcarnitine showed a striking difference with no change evident in mitochondria from denervated muscle and 80-85% decrease in dystrophic muscle. The study of succinate dehydrogenase and the enzymes of beta-oxidation in the above mitochondrial preparation showed similar findings except for acyl CoA dehydrogenase activity (an enzyme with a regulatory role in beta-oxidation) which was significantly diminished (29%) in denervated muscle, whereas no change was observed in dystrophic muscle. The findings show a close parallel in a number of parameters but distinct differences were observed in denervated as compared with dystrophic muscle. It is unlikely that the muscular disorder in murine muscular dystrophy can be explained solely on the basis of denervation or the loss of a neural trophic factor.

Acyl-CoA Dehydrogenases↗