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Biomedical subjects

M J Scott

Publications and source records attributed to M J Scott.

At least 73 records · Page 4Linked to original sources
PubMed1993

Isolation of cDNAs encoding 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase from the mediterranean fruit fly Ceratitis capitata: correlating genetic and physical maps of chromosome 5.

We have isolated and determined the nucleotide sequences for cDNA clones encoding glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) from the medfly Ceratitis capitata. The derived amino acid sequences for G6PD and 6PGD are presented and compared with G6PDs and 6PGDs from other species. The codon usage of the cDNA clones has little bias with the notable exceptions of arginine, glycine and leucine. The chromosomal location of the genes for 6PGD and G6PD were determined by in situ hybridization to salivary gland polytene chromosomes. This localization orients a genetic map of enzymatic loci and illustrates a remarkable similarity in the intra chromosomal order of homologous genes between Drosophila melanogaster and medfly.

Amino Acid Sequence↗
PubMed1993

Type IV collagen production by rat pulmonary alveolar epithelial cells.

Maintenance and repair of the pulmonary alveolar basement membrane are critical processes for preserving normal alveolar structure and function. To elucidate the mechanisms that control type IV collagen production by pulmonary alveolar epithelial cells, type II pneumocytes from rat lungs were isolated and maintained in tissue culture as monolayers. Using Northern blot analysis and metabolic labeling, we found that the cultured epithelial cells express type IV collagen mRNA and incorporate [3H]proline into type IV collagen. To determine the effects of phenotype on control of type IV collagen synthesis, we took advantage of the well-described observation that isolated type II cells lose their distinctive type II features when cultured on plastic in serum-containing medium for 7 days and assume an appearance more like that of type I epithelial cells. We found that [3H]proline incorporation into type IV collagen increased from day 1 to day 2 and thereafter decreased gradually up to day 7. Despite this decrease in [3H]proline incorporation, type IV collagen mRNA increased over the same period. If the loss of type II cell characteristics was prevented by culturing the cells in EHS matrix, a basement membrane-like extracellular matrix, there was little increase in relative abundance of type IV collagen mRNA as compared with cells cultured on plastic. We therefore conclude that type IV collagen production by isolated pulmonary alveolar epithelial cells is controlled, at least in part, by translational or post-translational mechanisms. Furthermore, the full type II cell phenotype is not required for expression of type IV collagen genes.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1992

On the structure of the nickel/iron/sulfur center of the carbon monoxide dehydrogenase from Rhodospirillum rubrum: an x-ray absorption spectroscopy study.

The nickel/iron/sulfur center of the carbon monoxide dehydrogenase (carbon monoxide:(acceptor)oxidoreductase; EC 1.2.99.2) enzyme from Rhodospirillum rubrum (Rr-CODH) was studied by x-ray absorption spectroscopy at the Ni K edge. Extended x-ray absorption fine structure data show that the first Ni coordination shell consists of 2 S atoms at 2.23 A and 2-3 N/O atoms at 1.87 A. The edge structure indicates a distorted tetrahedral or five-coordinate Ni environment in both oxidized and reduced Rr-CODH. By comparing second-shell extended x-ray absorption fine structure data of Rr-CODH to that of (Et4N)3[NiFe3S4(SEt)4], a cubane-type cluster, it was clearly established that Ni in the Rr-CODH center is not involved in the core of a NiFe3S4 cubane cluster. One model consistent with the results is a mononuclear Ni2+ site, bridged by S-Cys or sulfide to one or both of the Fe4S4 clusters of the enzyme, with the remaining coordination sites occupied by additional S-Cys or N/O-liganding amino acid residues.

Absorptiometry, Photon↗
PubMed1992

Cytogenetic analysis of pulmonary lavage and bone marrow cells of rats after repeated formaldehyde inhalation.

Cytogenetic analyses were conducted on bone marrow and pulmonary lavage cells from rats that received repeated inhalation exposures to formaldehyde. Male Sprague-Dawley rats were exposed to 0, 0.5, 3, or 15 ppm formaldehyde for 6 h per day, 5 days per week, for 1 and 8 weeks. There was no significant increase in chromosomal abnormalities in the bone marrow cells of formaldehyde-exposed rats relative to controls. There was a statistically significant increase in chromosomal aberrations in the pulmonary lavage cells from rats that inhaled 15 ppm. There were 7.6 and 9.2% of the scored pulmonary lavage cells that had aberrations following 1 and 8 weeks, respectively, of 15 ppm formaldehyde exposure (with control levels of 3.5 and 4.8%, respectively). The predominant damage seen was chromatid breaks. These findings indicate that marginal but statistically significant genotoxic effects could be detected locally in lung alveolar macrophages, but not distally in bone marrow, following repeated formaldehyde exposures only at a high concentration that is carcinogenic to rats. The biological significance of this effect is uncertain since formaldehyde is not considered to be a lung carcinogen in rats.

Administration, Inhalation↗
PubMed1992

Characterization of osteoblast-like cells from normal adult rat femoral trabecular bone.

Osteoblast-like cell cultures have been established from the trabecular surfaces of normal adult rat femoral trabecular bone. The cultured cells responded to stimulation by parathyroid hormone (rPTH), with a rise in intracellular cAMP in excess of 25-fold while failing to respond to incubation with sCT. Furthermore, the osteoblast-like cells exhibited a high level of alkaline phosphatase expression, both histochemically and biochemically. Incubations with 1,25(OH)2 vitamin D3 increased the alkaline phosphatase activity by 50% and stimulated bone Gla-protein (BGP) synthesis. When the cell layers were supplemented with both 50 micrograms/ml ascorbic acid and 10 mM beta-glycerophosphate and allowed to grow past confluency for 3 weeks, they formed calcified ridges and multilayered nodules. Confirmation of the mineralization of an extracellular matrix was made by von Kossa staining. This simple isolation technique now facilitates the availability of normal adult rat osteoblastic cells for investigation of bone and mineral metabolism.

Alkaline Phosphatase↗
PubMed1992

Squamous cell carcinoma in a tube pedicle forty years after jaw reconstruction.

Forty years following extensive jaw resection for adenocarcinoma in a young man, and innovative mandibular reconstruction, a squamous cell carcinoma developed in the tubed pedicle flap used to provide lining for the floor of the mouth. The case is described and a brief history of the early methods of mandibular reconstruction is presented.

Adenocarcinoma↗
PubMed1992

The effect of inoculation of Pasteurella haemolytica into the lactating mammary gland of mice, rats, rabbits, sows and cows.

An isolate of Pasteurella haemolytica (A9), which consistently produced severe mastitis in ewes, was inoculated into the lactating mammary glands of a variety of species. Mastitis did not develop after the inoculation of log-phase bacteria into the mammary gland of lactating mice, rats, rabbits or sows but did so in the mammary gland of two cows. Another A9 isolate from a ewe with mastitis and an A1 isolate from a bovine pneumonic lung also induced mastitis in cows. Thus, in this study, P. haemolytica produced mastitis only in ruminant animals.

Animals↗
PubMed1992

Effects of anabolic-androgenic steroids on the pilosebaceous unit.

Examination of skin biopsy specimens from persons using anabolic-androgenic steroids demonstrates dramatic hypertrophy of the sebaceous glands. High dosages of testosterone and anabolic-androgenic steroids, often self-administered by athletes, increase skin surface lipids, the cutaneous population of Propionibacteria acnes and the cholesterol and free fatty acids of the skin surface lipids. Acne, oily hair and skin, sebaceous cysts, hirsutism, androgenic alopecia, striae atrophicae, seborrheic dermatitis, and secondary infections including furunculosis may occur in persons using these drugs.

Acne Vulgaris↗
PubMed1992

Trapshooter's stigma.

We report an unusual episode of friction dermatitis combined with residual scarring in a member of the United States trapshooting team.

Adult↗
PubMed1991

Structure and expression of the Drosophila melanogaster gene encoding 6-phosphogluconate dehydrogenase.

We have determined the nucleotide sequence and structure of Pgd+, the Drosophila melanogaster gene that encodes the enzyme, 6-phosphogluconate dehydrogenase (6PGD). The derived 481-amino acid sequence for D. melanogaster 6PGD is presented and compared with 6PGD sequences from other species. To characterize the cis-acting sequences necessary for expression of Pgd+, fragments containing this gene as well as Pgd+ promoter-lacZ fusions were introduced into the D. melanogaster germ line by P-element-mediated transformation. Our results indicate that the large second intron is critical for Pgd+ expression in adults. Only 421 bp of Pgd+ 5'-flanking DNA are necessary to direct expression in imaginal discs, gonads and gut of third-instar larvae. Sequences downstream from the transcription start point are necessary for expression in the larval fat body.

Amino Acid Sequence↗
PubMed1991

The experimental production of mastitis in sheep by intramammary inoculation of Pasteurella haemolytica.

Acute mastitis was consistently produced in primiparous ewes by inoculation of the mammary gland, via the teat canal, with an isolate of Pasteurella haemolytica, serotype A9, originating from a field case of ovine mastitis. Mastitis developed following the inoculation of as few as 10 colony forming units of this isolate, suggesting that only a small number of organisms would be required to initiate the disease under natural conditions provided they were already beyond the teat canal. Clinical signs and macroscopic lesions were well developed within 24 h of inoculation and were similar to those found in the naturally-occurring disease. The ability to reproduce mastitis consistently will facilitate studies of the pathogenesis of the disease and the comparison of different isolates of P. haemolytica with respect to virulence determinants.

Acute Disease↗