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Biomedical subjects

B A Dale

Publications and source records attributed to B A Dale.

133 records · Page 8Linked to original sources
PubMed1975

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins of newbonr rat skin. II. Keratohyalin and stratum corneum proteins.

Keratohyalin extracts from newborn rat epidermis were prepared by potassium phosphate and citric acid-detergent extraction procedures. These preparations were compared by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and amino acid analysis. The major band of the potassium phosphate extract has a molecular weight of 48,000. The major bands of the citric acid-detergent preparation have molecular weights of 64,000, 61,500, 57,000 and 54,000. Electrophoresis of S-carboxylmethylated (SCM)-fibrous protein results in two major bands of approximately 57,000 and 64,000. SDS gels of the two preparations of keratohyalin and the SCM-fibrous protein were compared with gels of the insoluble proteins of granular and eluted cornified cells. All of the major bands in the preparations of keratohyalin can be seen in gels of the granular preparation. The two SCM-fibrous protein bands correspond with two prominent bands in gels of the cornified cell preparation. Two bands of the citric acid-extracted keratohyalin sample also have the same mobility. The major band of the potassium phosphate-extracted preparation of keratohyalin corresponds with a third prominent band of the cornified cell preparation. These results suggest that biochemical components of the preparations of keratohyalin are present in both the granular and the cornified layers of newborn rat epidermis.

Amino Acids↗
PubMed1972

Effect of the folic acid analogue, trimethoprim, on growth, macromolecular synthesis, and incorporation of exogenous thymine in Escherichia coli.

The effect of trimethoprim [2,4-diamino-5(2',4',5'trimethoxybenzyl)-pyrimidine] in the presence of thymine on Escherichia coli B temperature-sensitive and non-temperature-sensitive Thy(') strains and a phosphodeoxyribomutase-negative mutant was studied. The inhibitory effect of 5 mug of trimethoprim per ml on the growth of E. coli B was not overcome by thymine, thymidine, or thymidylate even in the presence of one-carbon metabolites and related metabolites. Deoxyribonucleic acid (DNA) and protein synthesis were more severely inhibited than ribonucleic acid (RNA) synthesis. The inhibition of DNA synthesis was partially reversed by addition of deoxyadenosine to increase the incorporation of exogenous thymine. By contrast, the inhibition of protein was not reversed even with one-carbon metabolites present, in keeping with the requirement for formylmethionyl-transfer RNA(F) for initiation. However, the inhibition of both DNA and protein synthesis in a phosphodeoxyribomutase-negative strain by 1 mug of trimethoprim per ml with thymine present was partially reversed by deoxyadenosine and one-carbon metabolites, and nearly normal growth occurred. 5-Fluorodeoxyuridine added at the time of addition of trimethoprim prevented the inhibition. Sulfadiazine in the presence of thymine inhibited both Thy(+) and Thy(-) strains whereas trimethoprim (with thymine) did not inhibit Thy(-) organisms. The effect of trimethoprim on the incorporation of labeled thymine into DNA was also studied. These experiments support the concept that trimethoprim in conjunction with the action of thymidylate synthetase inhibits the growth of Thy(+) cells because of a depletion of tetrahydrofolate. DNA synthesis is inhibited initially by a limitation of thymine nucleotide precursor, resulting from the indirect inhibition of thymidylate synthetase and the poor incorporation of exogenous thymine.

Anti-Bacterial Agents↗
PubMedDate not supplied

Biochemical examination of fetal skin biopsy specimens obtained by fetoscopy: use of the method for analysis of keratins and filaggrin.

This paper describes a method for biochemical analysis of proteins from fetal skin biopsy samples. The method has wide potential application for diagnosis of disorders with a known protein abnormality detectable by protein staining or a specific antibody. Analysis requires a single 1 mm biopsy, is rapid (2 days) and extremely sensitive. In the present study, fetal skin biopsies from normal fetuses and a fetus at risk for lamellar ichthyosis were obtained. The epidermis or hairs with attached follicular cells were dissected from the remaining skin. Proteins were extracted and separated by SDS-polyacrylamide gel electrophoresis. Proteins from duplicate gels were transferred to nitrocellulose and immunostained for the acidic and basic keratins and for the keratin filament associated protein, filaggrin, using monoclonal antibodies. All samples contained keratins typical of fetal epidermis at 20 weeks gestation. Presence of filaggrin is variable at this age and depends on the presence of keratinized cells of hair canals. No keratin abnormalities in the fetus at risk for lamellar ichthyosis were detected, however, in one presumably normal biopsy, an abnormally low proportion of the 67 kd keratin and the presence of follicular keratins were evident. These results demonstrate that biochemical analysis of fetal biopsies is possible, thus increasing the diagnostic potential of the fetal biopsy procedure for disorders in which a known protein or antigen is altered in utero.

Biopsy↗
PubMedDate not supplied

Altered retinoid distribution in the repeated epilation (Er) mutant mouse.

The repeated epilation (Er) mutation in mice causes successive loss and regrowth of hair in heterozygotes (Er/+), and blocks orofacial development and epidermal differentiation in lethal homozygotes (Er/Er). Because the mutation affects a systemic factor, because the Er phenotypes resemble exposure to excess retinoids and because retinoids are critical regulators of epithelial differentiation, we examined whether systemic retinoid levels are altered by the Er defect. Liver retinoic acid and retinol were elevated 1.5- and 3.5-fold, respectively, in adult heterozygotes (Er/+) compared to normal (+/+) animals. Retinyl palmitate was increased 2-fold in heterozygous skin and 3-fold in kidney, but the retinol level in plasma was only half that of normal animals. Newborn heterozygous liver also had nearly 2-fold increased retinoids compared to normal. In contrast, Er/Er newborns had reduced retinoid levels in liver, two-thirds the retinol and 15% the retinyl palmitate compared to normal, but greater than 4-fold elevated levels of retinyl palmitate in the extrahepatic body. Tissue contents of retinol binding protein (RBP), which transports vitamin A from the liver to the remainder of the body, were determined by immunoblotting with anti-mouse RBP. Newborn normal and mutant animals had similar liver microsomal RBP contents. RBP contents in plasma and in liver microsomes were also similar in normal and Er/+ adults despite different retinol contents in the Er/+ tissues. Hair follicles of the Er/+, but not the normal adult, were stained with this antiserum to RPB in the outer root sheath layer. These results strongly suggest that altered retinoid distribution is associated with, and may be responsible for, the altered epithelial differentiation in the Er mutant.

Animals↗
PubMedDate not supplied

Chromosomal localization of the retinol binding protein gene and its elimination as a candidate gene for the repeated epilation (Er) mutation in mice.

The repeated epilation (Er) mutation is an autosomal defect that blocks differentiation in stratified epithelia and appendages in mice. Plasma retinol binding protein (RBP) was tested as a possible candidate gene for the Er defect because of the importance of retinol as a modulator of epithelial morphogenesis and differentiation. Two approaches were used: (1) cloning and sequencing of the RBP cDNA from normal and mutant mice, and (2) the chromosomal localization of the mouse RBP gene. The mouse RBP sequence differs slightly from that of the rat RBP, but mutant and normal mouse RBP have identical sequences. The mouse RBP gene was localized by in situ hybridization to the distal portion of chromosome 19. This physical mapping confirms the recent assignment of the gene to chromosome 19 by linkage analysis. These results eliminate the RBP gene as a candidate gene for the defect in the Er mutation that maps to chromosome 4.

Amino Acid Sequence↗