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Biomedical subjects

M Thaler

Publications and source records attributed to M Thaler.

46 records · Page 3Linked to original sources
PubMed1980

Perinatal developmental changes in hepatic UDP-glucuronyltransferase.

Postnatal developmental changes in hapatic microsomal UDP-glucuronyltransferase were studied in the rat. The previously reported postnatal decline in the capacity of microsomal fractions to glucuronidate p-nitrophenol was found to be observable in unperturbed preparations only at non-saturating concentrations of the substrate UDP-glucuronic acid. At saturating concentrations of UDP-glucuronic acid, activity is identical in newborns and adults. Kinetic analysis revealed that the enzyme from liver of newborns has a much higher affinity for UDP-glucuronic acid than does the enzyme in adults, but the same activity at Vmax. On the other hand, the enzyme from adult liver microsomal fractions can be activated by the physiological allosteric effector UDP-N-acetylglucosamine, whereas the enzyme from newborns is largely unaffected by it. Thus it appears that the number of enzyme active sites is not changing; rather, the enzyme is maturing to a more highly regulable form. There were also differences between the enzymes in newborns and adults in their response to perturbation of the membrane-lipid environment by detergent and phospholipase A. Possible interpretations of these differences are discussed.

Aging↗
PubMed1980

Parameters of unbalanced growth and reversible inhibition of deoxyribnucleic acid synthesis in Brevibacterium ammoniagenes ATCC 6872 induced by depletion of Mn2+. Inhibitor studies on the reversibility of deoxyribonucleic acid synthesis.

Unbalanced growth induced by depletion of manganese ions was a prerequisite for production of ribonucleotides in a high salt mineral medium with the wildtype strain Brevibacterium ammoniagenes ATCC 6872. The concentration of manganese strictly controlled the overall deoxyribonucleic acid (DNA) synthesis, whereas ribonucleic acid (RNA), protein and cell wall synthesis remained essentially unimpaired in the manganese-lacking cells. The reversibility of inhibition of overall DNA synthesis was shown by enhanced incorporation (up to threefold compared to the cultures supplied with sufficient manganese) of [8-14C] adenine into alkali-stable, trichloroacetic acid-insoluble material after subsequent addition of 10 microM MnCl2 to 15 h-old depleted cultures. The results of inhibitor studies on the restoration of overall DNA synthesis due to subsequent addition of manganese ions to depleted cultures suggest that ribonucleotide reduction is the primary target of the manganese starvation during nucleotide fermentation with Brevibacterium ammoniagenes ATCC 6872.

Bacterial Proteins↗
PubMed1980

Comparative studies of keratins isolated from psoriasis and atopic dermatitis.

Keratin proteins were extracted from scales of normal skin, clinically active psoriatic lesions, and atopic dermatitis. Filaments prepared by in vitro assembly upon dialysis of the proteins against a low ionic strength buffer were comparatively characterized by electron microscopy, SDS gel electrophoresis, and amino acid analysis. Filaments formed using keratin obtained from the skin of normal individuals were thin and wavy, whereas those formed using keratin isolated from the scales of psoriatic patients were straight and showed a tendency to assemble side by side. Filaments of atopic dermatitis were indistinguishable from those of normal individuals. Filaments of both normal and atopic dermatitis contained the protein band of 67,000 daltons, which was absent in filaments of psoriasis. In contrast, 2 protein bands of 54,000 and 57,000 daltons were only detectable in psoriasis. Amino acid analysis of these filaments further demonstrated that filaments of psoriasis differ from those of normal individuals in that they have a glycine content that is 60% of normal.

Amino Acids↗
PubMed1979

Bacterial aggregating activity in human saliva: simultaneous determination of free and bound cells.

Two new assays for saliva-mediated aggregation of oral bacteria have been developed, based on the use of [3H]thymidine-labeled cells. One assay separates free cells from aggregated cells by centrifugation through sucrose, whereas the other utilizes membrane filters (8 micrometers, Nuclepore) to effect the separation. Comparison of these assays with the turbidity method reveals that they are faster (X20 to 40) and require 10 times less saliva and bacteria. The aggregation of Streptococcus sanguis M5, as determined with these assays, is complete in 5 min and is dose dependent on added cells and saliva. The reaction exhibits a temperature optimum of 42 degrees C with no reaction at 0 degrees C. If the pH is reduced to below 5, saliva-dependent aggregation is inhibited. The salivary factor(s) are heat labile, losing 100% of their activity after 100 degrees C, 10 min or 70 degrees C, 30 min.

Bacterial Physiological Phenomena↗
PubMed1977

Segmental obstructing acute jejunitis in a child.

Acute localized enteritis is a disease of the terminal ileum in adults and children. We have observed acute enteritis confined to the jejunum in a 3 1/2 year-old girl presenting with partial upper intestinal obstruction. Surgical biopsy of the involved region of jejunum revealed acute inflammatory changes in the mucosa and severe edema of the submucosa. Resection of the edematous segment was followed by prompt and apparently permanent recovery.

Biopsy↗