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Biomedical subjects

J M Land

Publications and source records attributed to J M Land.

17 recordsLinked to original sources
PubMed1992

Glutaric aciduria type 1 an atypical presentation together with some observations upon treatment and the possible cause of cerebral damage.

This report describes an infant diagnosed aged twenty-five months as having glutaric aciduria Type 1 (GA 1). Initial presentation was with isolated macrocephaly at four months of age. Severe hypertonia, and dystonia, within 24 hours of minor head injury occurred at nineteen months of age. Serial cranial imaging showed subdural fluid collections, and increasing underlying cerebral atrophy, mainly frontal and temporal. Confirmation of the clinical diagnosis required repeated blood and urine analysis by high performance liquid chromatography and gas chromatography/mass spectrometry; diagnosis was later confirmed enzymologically. Treatment with riboflavin, L-carnitine, vigabatrin and baclofen, produced some symptomatic relief; a low protein diet, nitrazepam and sodium valproate appeared of less obvious use. The rationale for these attempts at treatment is discussed. The possible role of quinolinic acid in the genesis of the fronto temporal and striatal atrophy is discussed and measurement of the quinolinate concentration in cerebrospinal fluid (CSF) of this case and age-related controls is presented.

Amino Acid Metabolism, Inborn Errors↗
PubMed1986

Prevention of cardiovascular disease in general practice: a proposed model.

A screening model based in general practice for the detection of subjects at risk of premature cardiovascular disease is described. Opportunistic screening is performed by a trained nurse who also gives initial advice on management. Immediate feedback to patients is possible since a rapid dry chemistry technique is used to measure blood cholesterol concentrations. The collation and analysis of data are achieved using a microcomputer. A central deidentified database is incorporated to allow epidemiological studies and intervention strategy evaluations to be made. Nineteen health centres have evaluated the model, and 40,000 subjects have been screened: 10% had diastolic blood pressures of over 95 mm Hg and 15% had a blood cholesterol concentration over 7 mmol/l (270 mg/100 ml) and 2% over 9 mmol/l (347 mg/100 ml). The initial data suggest that the model is acceptable to both health centre personnel and the general public and that the offer of screening is taken up by all elements of the target population.

Adult↗
PubMed1979

A mitochondrial myopathy with a deficiency of respiratory chain NADH-CoQ reductase activity.

This paper presents data on two sisters with a mitochondrial myopathy characterised by weakness, marked exercise intolerance and a fluctuating lactic acidaemia. Both patients also experienced episodes of increased weakness which could be brought on by unaccustomed activity, going without food or by taking small quantities of alcohol. Metabolic studies during exercise showed a marked and sudden rise in blood lactate and pyruvate levels. Biochemical studies in one case showed that mitochondrial respiratory rates were markedly decreased with all NAD-linked substrates tested but were normal with succinate and with TMPD + ascorbate. The mitochondrial cytochrome components were normal as determined by low temperature spectroscopy and the addition of uncoupler did not enhance state 3 respiratory rates utilising NAD-linked substrates. It was concluded, therefore, that the mitochondrial lesion was located at the level of the NADH-CoQ reductase complex.

Adult↗
PubMed1977

Development of mitochondrial energy metabolism in rat brain.

1. The development of pyruvate dehydrogenase and citrate synthase activity in rat brain mitochondria was studied. Whereas the citrate synthase activity starts to increase at about 8 days after birth, that of pyruvate dehydrogenase starts to increase at about 15 days. Measurements of the active proportion of pyruvate dehydrogenase during development were also made. 2. The ability of rat brain mitochondria to oxidize pyruvate follows a similar developmental pattern to that of the pyruvate dehydrogenase. However, the ability to oxidize 3-hydroxybutyrate shows a different developmental pattern (maximal at 20 days and declining by half in the adult), which is compatible with the developmental pattern of the ketone-body-utilizing enzymes. 3. The developmental pattern of both the soluble and the mitochondrially bound hexokinase of rat brain was studied. The total brain hexokinase activity increases markedly at about 15 days, which is mainly due to an increase in activity of the mitochondrially bound form, and reaches the adult situation (approx. 70% being mitochondrial) at about 30 days after birth. 4. The release of the mitochondrially bound hexokinase under different conditions by glucose 6-phosphate was studied. There was insignificant release of the bound hexokinase in media containing high KCl concentrations by glucose 6-phosphate, but in sucrose media half-maximal release of hexokinase was achieved by 70mum-glucose 6-phosphate 5. The production of glucose 6-phosphate by brain mitochondria in the presence of Mg(2+)+glucose was demonstrated, together with the inhibition of this by atractyloside. 6. The results are discussed with respect to the possible biological significance of the similar developmental patterns of pyruvate dehydrogenase and the mitochondrially bound kinases, particularly hexokinase, in the brain. It is suggested that this association may be a mechanism for maintaining an efficient and active aerobic glycolysis which is necessary for full neural expression.

Animals↗
PubMed1976

Glutamate metabolism and transport in rat brain mitochondria.

1. The metabolism and transport of glutamate and glutamine in rat brain mitochondria of non-synaptic origin has been studied in various states. 2. These mitochondria exhibited glutamate uptake and swelling in iso-osmotic ammonium glutamate, both of which were inhibited by N-ethylmaleimide. 3. The oxidation of glutamate was inhibited by 20% by avenaciolide, but glutamine oxidation was not affected. 4. These mitochondria, when metabolizing glutamine, allowed glutamate, but very little aspartate, to efflux at considerable rates. 5. These results suggests that brain mitochondria of non-synaptic origin possess in addition to a relatively rapid glutamate-aspartate translocase, a relatively slow aspartate-independent glutamate-OH-translocase (cf. liver mitochondria).

Aminooxyacetic Acid↗
PubMed1974

Differential effects of 2-oxo acids on pyruvate utilization and fatty acid synthesis in rat brain.

1. The effects of 2-oxo-4-methylpentanoate, 2-oxo-3-methylbutanoate and 2-oxo-3-methylpentanoate on the activity of pyruvate dehydrogenase (EC 1.2.4.1), citrate synthase (EC 4.1.3.7), acetyl-CoA carboxylase, (EC 6.4.1.2) and fatty acid synthetase derived from the brains of 14-day-old rats were investigated. 2. The pyruvate dehydrogenase enzyme activity was competitively inhibited by 2-oxo-3-methylbutanoate with respect to pyruvate with a K(i) of 2.04mm but was unaffected by 2-oxo-4-methylpentanoate or 2-oxo-3-methylpentanoate. 3. The citrate synthase activity was inhibited competitively (with respect to acetyl-CoA) by 2-oxo-4-methylpentanoate (K(i)~7.2mm) and 2-oxo-3-methylbutanoate (K(i)~14.9mm) but not by 2-oxo-3-methylpentanoate. 4. The acetyl-CoA carboxylase activity was not inhibited significantly by any of the 2-oxo acids investigated. 5. The fatty acid synthetase activity was competitively inhibited (with respect to acetyl-CoA) by 2-oxo-4-methylpentanoate (K(i)~930mum) and 2-oxo-3-methylpentanoate (K(i)~3.45mm) but not by 2-oxo-3-methylbutanoate. 6. Preliminary experiments indicate that 2-oxo-4-methylpentanoate and 2-oxo-3-phenylpropionate (phenylpyruvate) significantly inhibit the ability of intact brain mitochondria from 14-day-old rats to oxidize pyruvate. 7. The results are discussed with reference to phenylketonuria and maple-syrup-urine disease. A biochemical mechanism is proposed to explain the characteristics of these diseases.

Acetyl-CoA Carboxylase↗
PubMedDate not supplied

PHA dose dependent defect in lymphocyte stimulation and E-rosette-forming cells in untreated Hodgkin's disease.

14 untreated patients with Hodgkin's disease were tested for lymphocte reactivity in vitro to optimal and suboptimal doses of PHA. A PHA dose-dependent defect in lymphocyte stimulation was demonstrated in patients when compared with a group of normal individuals. No correlation between the in vitro defect and decreased absolute number of E-rosette-forming cells (T-lymphocytes) in peripheral blood was found.

Adolescent↗