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Biomedical subjects

H Baker

Publications and source records attributed to H Baker.

At least 217 records · Page 12Linked to original sources
PubMed1982

A simple method for determination of plasma and urinary biotin.

Measurement of biotin in plasma and urine has been stimulated by recent descriptions of inborn errors of biotin metabolism and by newly recognized causes of biotin deficiency. Biotin determination in physiologic fluids to document these conditions has been hindered by lack of a widely useable assay. This paper presents a method which employs tritium-labelled biotin, avidin, and nitrocellulose filters to measure urinary and plasma biotin in a rapid and simple manner.

Autoanalysis↗
PubMed1982

The inheritance and genetic correlation of tyrosine hydroxylase activities in the substantia nigra and corpus striatum in the C x B recombinant inbred mouse strains.

In mouse, strain differences in the activity of tyrosine hydroxylase (TH) in ventral midbrain dopamine systems of substantia nigra-A10 (SN) region of mouse brain and in a terminal field, the striatum (CS), can be entirely attributed to variations in the number of dopaminergic neurons2. To obtain further information about the complexity of the genetic systems influencing phenotypes for regional TH activity, we examined TH activity in the SN and CS of 7 recombinant inbred (RI) mouse strains, their progenitor strains (BALB/cBy and C57BL/6By), their reciprocal F1 hybrids and a CB6F2 segregating generation. Genetic analysis indicated that TH activity in both brain regions seems unlikely to be controlled by single gene effects. However, the mode of inheritance is presumably not very complex. Estimates of the degree of genetic determination for TH activity in SN and CS were relatively high with significant and positive correlations with respect to either the RI lines (r = 0.82) or the CB6F2 generation (r = 0.53). These positive correlations suggest that some of the genes of two gene sets influencing TH activities in the SN and CS are the same. However, additional non-shared genes may also be present. Assuming that our two measures reflect the number of dopaminergic neurons in SN-A10 area and density of their processes in corpus striatum, our results lead us to the hypothesis that the number of dopaminergic neurons and the axonal arborization of these neurons in the nigrostriatal system are in part under a common genetic control but that other genes may contribute to branching of SN neurons.

Animals↗
PubMed1982

Biochemical evidence for diverse etiologies in biotin-responsive multiple carboxylase deficiency.

Biotin-responsive multiple carboxylase deficiency can be categorized by clinical criteria into a neonatal-onset disorder and distinct syndrome of infantile onset. Pedigrees in each instance are consistent with autosomal recessive inheritance. For a neonatal-onset proband, the sensitivity to relative biotin deprivation and the rapid clinical response to biotin supplementation are reflected by in vitro studies. Specific activities of biotin-dependent pyruvate carboxylase, propionyl CoA carboxylase, and 1-methylcrotonyl CoA carboxylase are 0.8 to 16% of mean control values after growth of fibroblasts in intermediate and very low biotin concentrations. Following relative biotin depletion, pyruvate carboxylase activity returns to normal after only 14 hr of growth in biotin-supplemented medium. In contrast, carboxylase activities in fibroblasts of an infantile-onset proband remain normal at very low biotin concentrations, even when avidin is added to the growth medium. The clinical heterogeneity, taken together with the distinct responses of cultured skin fibroblasts to biotin deprivation in vitro, probably reflect fundamentally different etiologies for the two categories of biotin-responsive multiple carboxylase deficiency.

Adult↗
PubMed1982

Epidermolysis bullosa simplex generalisata: importance of immunofluorescence studies in early diagnosis.

An unusual case of severe generalized epidermolysis bullosa (EB) simplex is described. Its severity, oral involvement and early milia formation suggested a dystrophic form of the disease, but early immunofluorescence studies on skin biopsy material using bullous pemphigoid (BP) serum clearly showed the level of cleavage to be superficial to the dermo-epidermal junction and microscopy confirmed this. The diagnosis of EB simplex was thus quickly established allowing conservative treatment to be pursued with confidence, and preventing unnecessary exposure of the child to systemic corticoid or phenytoin therapy.

Epidermolysis Bullosa↗
PubMed1982

Time of appearance during development of differences in nigrostriatal tyrosine hydroxylase activity in two inbred mouse strains.

The greater activity of tyrosine hydroxylase (TH) in substantia nigra and corpus striata of adult BALB/cJ than CBA/J mice, is attributable to differences in the number of dopamine neurons in the ventral midbrain tegmentum. To determine if strain differences in TH activity develop postnatally we have measured the development of TH in the midbrain (SN) and in the corpus striatum (CS). In the midbrain neonatal TH activity was 20% of adult levels. Thereafter, TH activity increased rapidly achieving adult levels by 11 days. A 25% "overshoot' above adult values at 15 days was followed by a gradual decrease to adult activity at 4 weeks. In the CS neonatal activity was about 10% of adult levels and increased slowly to reach adult values at 4 weeks. Striatal choline acetyltransferase (CAT) activity in the neonate was only 3.7% of adult values and at 21 days had only reached 70% of adult activity. Neonatal glutamic acid decarboxylase (GAD) activity was relatively high in both brain regions and increased gradually to adult activity by 4 weeks. Strain differences in TH activity were not present at birth but first appeared at 9 days in SN and 11 days in CS. Once established, the differences were maintained. These results suggest that strain differences in TH are most probably a consequence of differences in postnatal neuron survival, although the possibility that some neurons lose their phenotypic expression of TH cannot be excluded.

Animals↗
PubMed1982

Micro-nutrient deficiency in a case of jejunoileal bypass.

This report describes various clinical and micro-nutrient abnormalities that existed in a 47-year-old woman who underwent a jejunoileal bypass operation. She exhibited extensive electrolyte, mineral, amino acid, and vitamin deficiencies. Amino acid absorption tests indicated an inability to absorb essential amino acids, especially the branched-chain and aromatic varieties. Vitamin absorption tests indicated an inability to notably absorb folic acid, niacin, vitamins B6, A, and E; the fat-soluble beta-carotene (provitamin A) was not absorbed from the diet. A liver biopsy revealed that 80% of the tissue was filled with fatty cysts. The ensuing liver disease compounded with biochemical abnormalities due to the bypass, contributed to the patient's death.

Amino Acids↗
PubMed1981

Role of placenta in maternal-fetal vitamin transfer in humans.

Vitamins B12, B6, biotin, folate, thiamine, riboflavin, pantothenate, and nicotinate were determined in maternal and fetal blood and placental tissue of normovitaminemic and hypovitaminemic mothers who disclaimed supplemental vitamin intake during pregnancy. No biotin or pantothenate deficits were observed in the gravidas. Hypovitaminemic mothers transferred less B12, folate, and B6 to the fetus and placenta than normovitaminemic mothers. Vitamins given by mouth increased maternal fetal, and placental levels of folate, but B6 increased only in maternal blood and the placenta; biotin and pantothenate increased only in fetal blood. Except for riboflavin, nicotinate, and pantothenate, the intramuscular administration of vitamins increased the levels of other vitamins in maternal and fetal blood and placental tissue. Results suggest that the placenta stores vitamins and the tissue vitamin receptors must be saturated before adequate transfer of vitamins to the fetus occurs.

Adolescent↗
PubMed1981

Elevated vitamin levels in colon adenocarcinoma as compared with metastatic liver adenocarcinoma from colon primary and normal adjacent tissue.

Twenty-four samples of colon adenocarcinoma removed at surgery and autopsy together with adjacent uninvaded normal colon from the same subjects were analyzed for vitamin B12 and B6, biopterin, nicotinate, riboflavin, pantothenate, thiamin, biotin, and folates. Nine specimens of metastatic liver adenocarcinoma from colon primary together with adjacent uninvaded normal liver were also analyzed for these same vitamins. Primary colon adenocarcinoma contains significantly (P less than 0.001) more of the above vitamins than normal colon; 1.8- to 3.5-fold higher concentrations of vitamins were found in this tumor. In contrast, vitamin B12 levels were almost two-fold lower. Unlike colon tumor, metastatic liver adenocarcinoma from colon primary contained from 1.2- to 28-fold lower vitamin concentration than normal liver tissue. The present findings suggest that those types of primary tumors with conspicuously high vitamin content needed for the enhanced growth and catalysis of tumor metabolism may be arrested with antivitamins targeted at metabolic sites other than those involved with nucleic acid synthesis.

Adenocarcinoma↗
PubMed1981

Biotin-responsive in vivo carboxylase deficiency in two siblings with secretory diarrhea receiving total parenteral nutrition.

Two siblings with a congenital syndrome of secretory diarrhea and seizures developed progressive skin rash, alopecia, and mucocutaneous candidiasis while receiving biotin-free total parenteral nutrition. Abnormally low urinary biotin excretion was associated with these clinical findings, but the serum concentration of biotin was within the normal range. There was also increased urinary excretion of lactic acid, 3-hydroxyisovaleric acid, 3-hydroxypropionic acid, and 3-methylcrotonylglycine. The younger of the two children subsequently died with severe metabolic acidosis. In the oder sibling, intravenous treatment with biotin (200 micrograms/day) resulted in resolution of the organic aciduria. A larger dose (10 mg/day) appeared to be required for rapid improvement in the skin lesions. These cases suggest that clinically significant biotin deficiency can occur in patients with chronic diarrhea receiving biotin-free total parenteral nutrition.

Biotin↗