PubMed Health⌕ Search

Biomedical subjects

J F Nicholson

Publications and source records attributed to J F Nicholson.

At least 19 recordsLinked to original sources
PubMed1983

Benign infantile mitochondrial myopathy due to reversible cytochrome c oxidase deficiency.

A 2-week-old boy had profound generalized weakness, hypotonia, hyporeflexia, macroglossia, and severe lactic acidosis. The infant improved spontaneously: he held his head at 4 1/2 months, rolled over at 7 months, and walked by 16 months. At 33 months of age, he had mild proximal weakness. Macroglossia disappeared by age 4 months. Blood lactic acid declined steadily and was normal by 14 months of age. Histochemical and ultrastructural studies of muscle biopsy specimens obtained at 1 and 7 months of age showed excessive mitochondria, lipid, and glycogen; a third biopsy at age 36 months showed only atrophy of scattered fibers. Cytochrome c oxidase stain was positive in fewer than 5% of fibers in the first biopsy, in approximately 60% of fibers in the second biopsy, and in all fibers in the third biopsy. Biochemical analysis showed an isolated defect of cytochrome c oxidase activity, which was only 8% of the lowest control level in the first biopsy; the activity increased to 47% in the second biopsy and was higher than normal in the third. In contrast to that in the fatal infantile form of cytochrome c oxidase deficiency, the enzyme defect in this condition is reversible. The biochemical basis for this difference remains to be explained.

Acidosis↗
PubMed1982

A new microfluorometric method for the measurement of galactose-1-phosphate in erythrocytes.

A new and sensitive assay for measuring galactose-1-phosphate in erythrocytes is described. Galactose-1-phosphate is determined by mixing an aliquot of deproteinized hemolysate with a reagent containing uridine diphosphoglucose, NADP+, hexose-1-phosphate uridylyltransferase, phosphoglucomutase, glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase and measuring the NADPH formed fluorometrically. Under the conditions of this assay 2 mol of NADPH are formed per mol of galactose-1-phosphate. The assay is linear from 0 to 1160 micrograms of galactose-1-phosphate per gram of hemoglobin. Recovery of galactose-1-phosphate added to four hemolysates averaged 99%. Galactose-1-phosphate concentrations were measured in erythrocytes from five heterozygous subjects not under dietary control and seven transferase-deficient galactosemic individuals who were receiving galactose restricted diets. In all samples from the heterozygous individuals, the galactose-1-phosphate concentrations were normal. Of the samples from galactosemic subjects, two showed extreme elevations of galactose-1-phosphate, four showed moderate elevations, and one was normal. Galactose-1-phosphate levels are used to monitor the degree of dietary control in the transferase-deficient galactosemic individual.

Adolescent↗
PubMed1979

Effects of essential fatty acid deficiency on various functions of the rat erythrocyte membrane.

Various membrane transport functions have been studied in erythrocytes from essential fatty acid (EFA) deficient rats in order to determine whether or not functional abnormalities induced by documented EFA-deficiency of the membrane could be demonstrated. No differences were found between EFA deficient and control cells with respect to mean values for osmotic resistance or intracellular sodium and potassium concentrations. However, uptake of leucine by EFA deficient erythrocytes was significantly greater than that of control erythrocytes. Kinetic studies suggest that EFA deficiency enhances the passive diffusion component of this transport.

Animals↗
PubMed1979

A controlled trial of glucose versus glucose and amino acids in premature infants.

A controlled study comparing two intravenous fluid regimens was performed in sick, premature infants. The regimens were isocaloric at 60 calories/kg/day, one providing glucose alone, the other glucose plus 2.5 gm/kg of amino acids. There was no difference in changes in body weight between the two groups; infants receiving glucose alone were in negative nitrogen balance; those receiving glucose plus amino acids were in positive nitrogen balance. Plasma amino acid values were compared to published, postprandial normal values. The TEAA and TAA of infants receiving amino acids were not different from normal. Values of TEAA and TAA of infants receiving glucose alone were significantly lower. Essential fatty acid deficiency developed in infants receiving amino acids but not in those receiving glucose alone. It is concluded that the glucose plus amino acid regimen results in anabolism without undue metabolic costs.

Amino Acids↗
PubMed1979

Adenine nucleotide translocation in liver mitochondria isolated from rats deficient in essential fatty acids.

Adenine nucleotide content and adenine nucleotide transport were evaluated in rats deficient in essential fatty acids (EFA) and in control rats. ADP uptake by EFA-deficient mitochondria was altered in a manner similar to the alteration produced by treatment of normal mitochondria with uncoupler. The uptake of ATP by EFA-deficient mitochondria was more rapid than that of normal mitochondria, but similar to that of normal mitochondria treated with uncoupler (DNP). Both uptake of ADP and uptake of ATP by EFA-deficient mitochondria were atractyloside sensitive. Total adenine nucleotide content of liver mitochondria from EFA-deficient rats was similar to that of liver mitochondria from control animals, but the content of ATP in EFA-deficient mitochondria was significantly higher than that of normal mitochondria. There was a negative correlation between the concentration of linoleic acid in total mitochondria lipids and ATP content of mitochondria.

Adenine Nucleotides↗
PubMed1977

Genetics of juvenile diabetes mellitus. A recessive gene closely linked to HLA D and with 50 per cent penetrance.

We investigated the genetic predisposition to juvenile diabetes in the families of 31 index cases in relation to the inheritance of the HLA system. The diabetes-predisposing gene was found to be recessive because the diabetic sibs in index cases shared both their HLA genes with a significantly increased frequency. Penetrance was estimated at 50 per cent because half the HLA-identical sibs in index cases were diabetic. These conclusions fit with published observations that the risk to sibs of patients is about 100 per cent, when both parents are normal. In three informative cases of recombination within HLA the predisposing gene traveled with the HLA D segment of the recombinant haplotype. We prepared tables for the computation of risks to relatives, based on the hypothesis of recessivity, HLA linkage and 50 per cent penetrance.

Adolescent↗
PubMed1977

The HLA system and the genetics of juvenile diabetes mellitus.

Eighteen families with a total of 68 children were completely typed for HLA-A, B, C, D and Bf. With only one exception, all affected children within each family with 2 or more diabetic siblings, shared both HLA-D alleles indicating that J.D.M. is a recessive trait. Since half of the siblings who are HLA-D identical to the first affected child developed J.D.M. (as is the case of monozygotic twins), the gene(s) in question is most likely the sole genetic requirement for this disease and has a penetrance of 50%. No evidence of association between J.D.M. and B8, Dw3 or Bw15 was observed by analyzing the segregation of J.D.M. and of each of the above HLA antigens in informative families. A total of 9 out of 68 children bore a recombinant HLA haplotype. This increased rate of crossing-over in J.D.M. seems to require a single J.D.M. gene since the parents (9) in whom recombinations occurred were non-diabetic. No association was seen between the presence of the disease and the existence of a recombinant hoplotype.

Adult↗
PubMed1977

Intra-HLA recombinations in juvenile diabetes mellitus.

Complete HLA and Bf typing of 18 families with juvenile diabetes mellitus (J.D.M.) showed that of 68 children, 9 bore recombinant haplotypes (13%). This frequency is significantly higher than the currently accepted 1.6% for intra-HLA recombinations with a p of 1.3 X 10(6) (binomial expansion) and may be related to the J.D.M. gene itself. Five of the nine crossovers were between HLA-A and B, and four between HLA-B and D. In one informative A/B recombination, Bf segregated with the HLA-B-D segment while in another two, it segregated in cis with HLA-A. This suggests the existence of two genetic sequences within the HLA region, one with Bf on the A site and a second one with Bf on the D site.

Adult↗
PubMed1976

The HLA system in the families of patients with juvenile diabetes mellitus.

The HLA and Bf genotypes were determined in 10 families with one or more children with JDM. A statistically significant association was found between HLA-D-identity and the chance to present JDM within a sibship. No such association was detectable with the SD antigens. A highly significant increase in the frequency of intra-HLA recombination was also found in these families.

Diabetes Mellitus, Type 1↗
PubMed1976

The prevention of postprandial seizures in children.

Three boys are reported who showed typical autonomic manifestations of hypoglycemia in association with stupor or convulsive seizures two to four hours after eating a meal. During glucose tolerance tests all three children had high peaks in plasma glucose within the first hour and subsequently developed symptoms typical of their clinical disorders on at least one occasion. Two of the boys showed appropriate responses of plasma insulin to oral glucose loading; the third showed a delay in peak plasma insulin. All three children responded promptly and completely to simple dietary management.

Blood Glucose↗
PubMed1975

Rapid kinetic measurement of lactate in plasma with a centrifugal analyzer.

In this method, blood is collected in ammonium heparinized microhematocrit tubes and lactate is directly determined in the plasma, separated within 15 min from the erythrocytes. Lactate is assayed by mixing 10 mul of sample with NAD+ and lactate dehydrogenase in tris(hydroxymethyl)aminomethane hydrazine buffer. The rate of increase in absorbance of the NADH formed, measured at 340 nm, is proportional to lactate concentration. The assay is complete in 4 min and absorbance is linearly related to concentration from 0.625 to 15 mmol/liter. Analytical recoveries of lactate added to plasma averaged 104% (range, 91-116%). Results compared well for plasma samples analyzed by this method with the CentrifiChem and the Du Pont aca.

Centrifugation↗