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Biomedical subjects

D G Smith

Publications and source records attributed to D G Smith.

At least 289 records · Page 16Linked to original sources
PubMed1981

Birth timing and social rank of adult male rhesus monkeys (Macaca mulatta).

The distribution of birth dates of offspring of high-ranking adult males was compared with that of offspring of low-ranking adult males. A significantly greater number of the offspring of high-ranking males were born earlier during the birth season than were those of low-ranking males (chi 2(2) = 10.00, p less than 0.01). Higher reproductive success might be maintained by adult rhesus monkeys of high rank not only by the intensity but also by the timing of their mating activity.

Animals↗
PubMed1980

Paternity exclusion in six captive groups of Rhesus monkeys (Macaca mulatta).

Five genetic markers were employed to attempt to identify the fathers of 135 Macaca mulatta offspring living in large outdoor field cages. Family studies of two of these markers to confirm mode of inheritance of phenotypes had not heretofore been reported. Of the 284 exclusions required to identify the fathers of all 135 monkeys, 198 (or 70 percent) were possible using only these five genetic polymorphisms. For 58 (or 43 percent) of these 135 offspring the father was identified. These data were applied to estimate the association between dominance rank of fathers and reproductive success. Fertility of first- and second-ranking fathers was judged to be about twice as high as that of third- and fourth-ranking fathers.

Animals↗
PubMed1980

Petrous angle and trigeminal neuralgia.

The angle of the petrous portion of the temporal bone was measured at the site where it is crossed by the trigeminal nerve. Measurement was facilitated by using the impression techniques of dentistry to produce a plaster model of the bone, and the model was then sawn across to show the angle clearly. Considerable variation was found. Certain bone irregularities were observed and these could also conceivably be factors in the causation of trigeminal neuralgia. An attempt to reveal the angle of the petrous bone by radiology was successful in some cases but not in others. Further investigation along these lines might be of value in patients suffering from idiopathic trigeminal neuralgia.

Humans↗
PubMed1980

Proof for the biosynthetic conversion of L-[indole-15N]tryptophan to [10-15N]anthramycin using (13C, 15N) labelling in conjunction with 13C-NMR and mass spectral analysis.

Using 13C-NMR and mass spectral analysis we have demonstrated that the N-10 nitrogen of anthramycin is biosynthetically derived from the indole-nitrogen of tryptophan. Our experimental approach was to bring a 15N atom, which is derived from L-[indole-15N]tryptophan, and a 13C atom which is derived from DL-[1-13C]tyrosine, into adjacent positions of anthramycin. From resonance intensities and 13C-15N spin-spin coupling in the 13C-NMR spectrum of didehydroanhydroanthramycin, a derivative of anthramycin, we could then determine the 13C enrichment at C-11 and the proportion of 13C bonded to 15N at N-10. These results when combined with mass spectral analysis and isotopic dilution measurements proved that the indole nitrogen of tryptophan was completely retained at N-10 of anthramycin.

Amino Acids↗
PubMed1980

Effect of cryo-protective agents on the growth and ultrastructure of Saccharomyces cerevisiae.

When suspended in a glucose medium supplemented with varying amounts of DMSO, ethylene glycol, glycerol, lactose and sodium chloride at its optimum temperature of 30 degrees C, a diploid strain of Saccharomyces cerevisiae gave a mean generation time inversely proportional to the increased concentrations of these anti-freeze compounds. No growth was attained at 0 degrees C and -5 degrees C, and mixtures of the compounds did not support any growth even at 30 degrees C. At 0 degrees C and -5 degrees C with increasing percentages of the individual compounds, and at 30 degrees C, 0 degrees C and -5 degrees C, with mixtures of the compounds, a significant decrease in survival was obtained. As compared to cells grown in the absence of antifreeze compounds, electron microscopy of the cells which grew at 30 degrees C in the presence of antifreeze compounds showed thicker cell walls, highly convoluted plasmalemma, vacuoles filled with electron-dense fibrous material, spherosomes, poorly developed mitochondria and many vesicles.

Cell Membrane↗
PubMed1979

Effects of insulin on lipolysis and lipogenesis in adipocytes from genetically obese (ob/ob) mice.

A method for the preparation of isolated adipocytes from obese mice is described. Similar yields of adipocytes (50--60%), as judged by several criteria, are obtained from obese mice and lean controls. Few fat-globules and no free nuclei were observed in cell preparations, which are metabolically active, respond to hormonal control and appear to be representative of intact adipose tissue. Noradrenaline-stimulated lipolysis was inhibited by insulin, equally in adipocytes from lean and obese mice. Inhibition in obese cells required exogenous glucose, and the insulin dose--response curve was shifted to the right. Basal lipogenesis from glucose was higher in adipocytes from obese mice, and the stimulatory effect of insulin was greater in cells from obese mice compared with lean controls. A rightward shift in the insulin dose--response curve was again observed with cells from obese animals. This suggests that adipose tissue from obese mice is insulin-sensitive at the high blood insulin concentrations found in vivo. The resistance of obese mice to the hypoglycaemic effect of exogenous insulin and their impaired tolerance to glucose loading appear to be associated with an impaired insulin response by muscle rather than by adipose tissue.

Adipose Tissue↗
PubMed1979

Alterations in the cell envelope composition of Proteus mirabilis during the development of swarmer cells.

Long, swarming cells of Proteus mirabilis had different proportions of some lipopolysaccharide components when compared to short cells, either agar grown or broth grown. Fluorescence spectrophotometry of antibody binding, and sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicated that the change was in the proportion of lipopolysaccharide with long O-antigenic sidechains, swarmer lipopolysaccharide relative to short sidechain lipopolysaccharide than the non-swarming cells. The proteins and phospholipids of the envelop remained the same during swarmer development. The results are discussed in relation to the increase in flagella synthesis and permeability to some antibacterial agents during swarmer development.

Binding Sites, Antibody↗
PubMed1979

The genetic hypothesis for susceptibility to lepromatous leprosy.

Evidence for genetic influence of the host response to infection with Mycobacterium leprae is reviewed. A complex segregation analysis is performed on data for 91 families from Mactan, Philippines, in each of which at least one offspring developed lepromatous leprosy. The data are not found to be inconsistent with an autosomal recessive hypothesis for susceptibility to lepromatous leprosy. Heritability estimates in the range of 80% were calculated for sib-sib pairs under the multifactorial hypothesis for susceptibility. It is argued that the multifactorial hypothesis is more in keeping with available immunologic, epidemiologic, and demographic data than is the single gene hypothesis.

Female↗
PubMed1979

Inheritance of Indian childhood cirrhosis.

Detailed pedigree charts were prepared from 120 index patients suffering from Indian childhood cirrhosis (ICC). Of the 120 families, 84 were informative for segregation analysis. Since families were ascertained through patients who came to hospital for treatment, the data were analyzed according to a single-selection model. The observed segregation ratio for the entire data was significantly lower than the one expected under the hypothesis of autosomal recessive inheritance (p = smaller than 0.005). On the other hand, the segregation data for families with at least two affected children (multiplex families) were compatible with autosomal recessive inheritance. On this basis, however, at least 50% of all the cases of ICC would have to be of nongenetic origin. Alternatively, analysis of the data by the Falconer method indicated that ICC could be of multifactorial origin with very strong genetic determination (over 85%).

Age Factors↗
PubMed1979

Growth and survival studies of psychrophilic and mesophilic yeasts.

The effect of temperature on the growth of members of five genera of yeasts was studied in one glucose-containing and two glucose-free media. The maximum growth rate was seen in the glucose-containing medium, and the minimum growth was in either of the two glucose-free media depending upon the organism. Data obtained by optical density measurements was supported by total cell counts. The highest survival at the restrictive temperatures was within 5 degrees C of the optimum temperature for a particular organism. Among the temperatures other than the optimum, the highest growth rate and cell yield was obtained at a temperature 5 degrees C below or above the optimum.

Candida↗
PubMed1979

The fine structure of psychrophilic and mesophilic Rhodotorula rubra.

Transmission electron microscopy of thin sections of two mesophilic and a psychrophilic Rhodotorula rubra revealed structures normally associated with yeast. The capsule of all three strains was thicker in the cells grown in glucose than those grown in glucose-free media. The cell wall of all three strains showed more lamellae in the cells grown in a medium containing glycerol. Budding was of the Rhodoturula type. Endoplasmic reticula running parallel to the nucleus were commonly observed in the psychrophiles but not in the mesophiles. In the psychrophile, in association with the plasmalemma, lomasomes and plasmalemmasomes were observed. Giant mitochondria were commonly seen in the cells grown in a fermentable carbohydrate-free medium. Vacuoles were mostly empty.

Cell Membrane↗
PubMed1978

The genetic hypothesis for the transmission of Australia antigen (HBsAg).

Exceptions have been cited which rule against the simple autosomal recessive hypothesis for the transmission of susceptibility to infection with Australia antigen (HBsAg). An attempt is made here to present a genetic model for a complex segregation analysis of a new and unique set of data to test this hypothesis. Regression techniques were used to estimate in four populations, age and sex-specific penetrance levels and the frequency of the gene whose product is hypothesized to be HBsAg. While the genetic hypothesis was not in general supported, observed deviations and their possible causes are discussed.

Adolescent↗