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Biomedical subjects

D Scott

Publications and source records attributed to D Scott.

At least 307 records · Page 17Linked to original sources
PubMed1986

The unique sensitivity of Walker rat tumour cells to difunctional agents is associated with a failure to recover from inhibition of DNA synthesis and increased chromosome damage.

The rate and mode of DNA synthesis was examined by thymidine uptake and by flow cytometry in Walker tumour cells highly sensitive to difunctional agents (WS), and in a derived subline of resistant cells (WR) (Rawlings and Roberts, 1986), following their treatment with sulphur mustard. Both cell lines exhibited the same dose-dependent and progressive depression in rate of DNA synthesis for up to 4 h after treatment. Thereafter the depression in rate of synthesis was partially reversed in the WR cells but DNA synthesis continued to decrease in the WS cells resulting in their slower transit through the S phase and a persistent block in the G2/M phase of the cell cycle. Sensitive cells which finally escaped the block in G2 carried more chromosome aberrations than the corresponding resistant cells. Neither cell line was defective in daughter strand-gap repair. In their sensitivity to difunctional but not to monofunctional compounds, their failure to recover from the early depression of DNA synthesis, their apparent lack of a defect in excision repair and their sensitivity to chromosome aberration induction, the Walker cell phenotype closely resembles that of the human Fanconi's anaemia cell.

Animals↗
PubMed1986

Meconium periorchitis: a clinicopathologic study of four cases with a review of the literature.

Perforation of the bowel wall in utero, with meconium gaining access to the tunica vaginalis, results in meconium periorchitis. The clinical and pathologic features in four infants were studied; the findings were compared with those in the 20 cases reported in the literature. In the majority of cases, the intestinal perforation had apparently healed before birth, and the scrotal mass became increasingly obvious following birth. Cystic fibrosis was documented in only one case. A yellowish green paratesticular mass with multifocal dystrophic calcification was the principal gross finding. Lobules of fibromyxoid tissue containing the calcifications were separated by bands of connective tissue. A granulomatous reaction per se was not prominent in the four cases of the present study, although some authors have characterized the process as meconium granuloma. Before orchiectomy is performed in an infant with a scrotal mass, the possibility of meconium periorchitis should be considered.

Calcinosis↗
PubMed1986

Surgical repair of visceral artery occlusions in Takayasu's disease.

We describe the surgical management of six patients with occlusive disease of the visceral arteries caused by Takayasu's arteritis. All patients suffered from renovascular hypertension and, in addition, three of the patients also had symptoms of mesenteric angina. Surgical repair is recommended in the "burn-out" phase of the disease when further progression of the disease is unlikely. Revascularization of the kidneys was by autotransplantation to the iliac vessels. Mesenteric or celiac artery inflow was provided by an extra-anatomic vein bypass graft from the iliac artery. In all cases distal disease-free vessels were available for reconstructive surgery.

Adolescent↗
PubMed1986

Sexual mimicry regulates the attractiveness of mated Drosophila melanogaster females.

During mating, male Drosophila melanogaster transfer to the female's cuticle a compound (7-tricosene) that is almost absent from virgin females but is the major hydrocarbon component of the male's cuticle. During the first 3 hr after mating, the amount of 7-tricosene on a female decreases sharply but remains significantly above virgin levels. By 6 hr after mating, female synthesis of 7-tricosene has increased, and females release it when they are exposed to courting males. Transfer of 7-tricosene to immature virgin females by courting males significantly decreases their attractiveness, so 7-tricosene has demonstrable antiaphrodisiac properties. Thus, mated D. melanogaster females appear to mimic males by releasing, during courtship, an antiasphrodisiac pheromone that is almost absent from virgin females but is the most prominent hydrocarbon of the male cuticle.

Alkenes↗
PubMed1986

Chromosome aberration induction in human diploid fibroblast and epithelial cells.

The relative sensitivity of cultured human fibroblasts and epithelial cells to radiation-induced chromosomal aberrations was investigated. Lung fibroblast and kidney epithelial cells from the same fetus were compared, as were skin fibroblasts and epithelial keratinocytes from the same foreskin sample. After exposure of proliferating fetal cells to 1.5 Gy X-rays there was a very similar aberration yield in the fibroblasts and epithelial cells; the mean frequency between 1 and 72 h post-irradiation was 25 and 29% aberrant cells, respectively. After 1.5 Gy the corresponding values in skin fibroblasts and epithelial cells were 16.5 and 11.2%, respectively, and after 2.5 Gy, 31.3 and 30%. These observations of either little or no difference in chromosomal sensitivity between human fibroblasts and epithelial cells give added confidence that quantitative cytogenetic data obtained from cultured fibroblasts are relevant to the question of sensitivity of epithelial cells which are the predominant cell type in human cancers.

Cells, Cultured↗
PubMed1986

Spotting the spot.

Explore the source record for details and available documents.

Health Education↗
PubMed1986

Morphologic effects of bromocriptine on spontaneously occurring pituitary prolactin-cell hyperplasia in old Long-Evans rats.

The effect of bromocriptine (BEC), a dopaminergic agonist, on nontumorous pituitary prolactin (PRL) cells of aging female Long-Evans rats, was studied histologically, immunocytologically, electron-microscopically, and morphometrically. Rats were arbitrarily divided into two control groups, one with normal (less than 20 ng/ml) and one with elevated serum PRL concentrations, and into four BEC-treated groups, all of which had increased serum PRL levels prior to commencement of BEC administration. In hyperprolactinemic control rats, compared with normoprolactinemic control rats, pituitary weight and percentage of pituitary PRL cells were increased. The morphologic features of PRL cells in these two groups did not differ markedly, which suggested that hyperprolactinemia was due to increased PRL-cell number and not increased PRL-cell function. Compared with age-matched hyperprolactinemic control rats, hyperprolactinemic rats treated with BEC showed a reversible decrease in serum PRL levels, pituitary weight as well as percentage of pituitary PRL cells, and by ultrastructural morphometry an increase in the volume density of lysosomes. BEC caused no striking changes in nuclear and cytoplasmic areas, volume densities of RER, Golgi regions, mitochondria, lipid droplets, and size and volume densities of forming and storage granules. Since spontaneously hyperplastic PRL cells show less conspicuous morphologic changes following BEC treatment than PRL cells rendered hyperplastic by estrogen administration or pituitary transplantation, it is suggested that PRL cells with no increased endocrine function respond less markedly to dopaminergic suppression than endocrinologically hyperactive PRL cells. It can be concluded that BEC suppresses spontaneous proliferation of PRL cells which occurs with aging.

Aging↗
PubMed1985

Characterization of mammalian neurofilament triplet proteins. Subunit stoichiometry and morphology of native and reconstituted filaments.

The three major proteins of mammalian neurofilaments of molecular weights 179,000 (NF1), 129,000 (NF2), and 66,500 (NF3) have been purified to homogeneity by multiple anion-exchange and hydroxylapatite absorption chromatography in 8 M urea. Silver staining of polyacrylamide gels of the purified proteins show single bands. In order to gain further insight into the molecular organization of the neurofilament triplet proteins, the molar stoichiometries and morphologies of native and reconstituted filaments and those isolated from developing brain were studied. Denaturing polyacrylamide gel electrophoresis followed by quantitative dye-binding analysis shows that the molar ratio of the three components in neurofilaments isolated from bovine spinal cord myelinated nerve is 4:2:1 (NF3:NF2:NF1). Comparison of the molar ratios of each component in neurofilaments isolated from rat, bovine, and human brain shows a variation in the ratio of each of these polypeptides and raises questions about the physiological uniqueness of the molar composition of the neurofilament triplet. Reconstitution of the three bovine polypeptides into 10-nm filaments was accomplished under conditions in which the NF3 protein was limiting. Reassembly of 10-nm filaments with varying amounts of NF2 and NF1 indicate that the NF3 homopolymer has a limiting capacity to bind NF2 and NF1 and is saturated at a molar ratio of 2:2:1 (NF3:NF2:NF1). Isolation of the neurofilament complex at various stages of rat brain maturation indicates that NF3 and NF2 are integrated into the neurofilament complex as early as embryonic day 17, while NF1 copurifies with these proteins at postnatal day 16, eventually reaching a molar stoichiometry of 2:2:1 in the adult rat. The molecular stoichiometry of the neurofilament proteins, the differential integration of these proteins during brain development, and the variation of the molar composition between mammalian species suggest accessory roles for the NF2 and NF1 proteins in the neurofilament complex.

Amino Acids↗
PubMed1985

Crystals of crotoxin suitable for high resolution x-ray diffraction analysis.

The phospholipasic presynaptic neurotoxin, crotoxin, has been crystallized in a morphology suitable for single crystal x-ray diffraction analysis. The conditions for growth and the unit cell parameters (P4(1)22 or P4(3)22, a = b = 38.5 A, c = 256.9 A, 1 molecule/asymmetric unit) are similar to the very thin plate-like crystals which have been studied with electron diffraction and electron microscopy by Chiu and his colleagues (Jeng, T.-W., Chiu, W., Zemlin, F., and Zeitler, E. (1984) J. Mol. Biol. 175, 93 - 97). These two macroscopic crystal morphologies of what is likely to be a very similar, if not identical, lattice structure will permit the complementary application of electron diffraction/microscopy and x-ray diffraction to understanding the structural basis of the interactions between a phospholipasic neurotoxin and its membrane target.

Animals↗
PubMed1985

Molecular forms of acetylcholinesterase in Hirschsprung's disease.

We describe changes in the levels of different molecular forms of acetylcholinesterase in four cases of Hirschsprung's disease linked to the transition from aganglionic to normal bowel. In addition changes in a control case with histologically normal bowel is reported. In all patients with Hirschsprung's disease there is a marked increase in the level of the tetrameric form of the enzyme in the aganglionic region. The changing level of this form of the enzyme correlates well with the histochemical appearance suggesting that quantitative measurement of this molecular species might form the basis of an improved diagnostic test for the disease.

Acetylcholinesterase↗
PubMed1985

Acute water intoxication following pelvic ultrasound examination.

Ultrasonography is a widely used imaging technique whose popularity is based, in part, on its reputation for being relatively without risk to the patient. Like most procedures, however, ultrasound studies may be associated with complications, as the case presented here illustrates. A 79-year-old woman was given a large oral water load before a pelvic ultrasound examination and experienced symptoms of acute water intoxication afterward. When hyponatremia was corrected, the patient's condition returned to normal.

Acute Disease↗