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Biomedical subjects

M Barber

Publications and source records attributed to M Barber.

At least 55 records · Page 3Linked to original sources
PubMed1988

Studies on sperm survival and motility in the presence of cytotoxic sperm antibodies.

The effect of cytotoxic sperm antibodies and native complement in the serum and secretions from 40 fertile and 93 infertile couples on in vitro sperm survival and motion characteristics was studied. Sperm survival in vitro was unaffected by sera from fertile and infertile subjects without cytotoxic sperm antibodies and from infertile men with antibodies to control but not to autologous sperm. Sperm survival was reduced (P less than .001) by sera from infertile men with antibodies to autologous sperm or to antologous and control sperm and from women with cytotoxic antibodies to sperm from both. Sera from fertile couples without sperm antibodies enhanced sperm swimming speed and motility index (P less than .0001). Sera from infertile women with or without cytotoxic sperm antibodies did not affect sperm motility. Sperm survival and motility were reduced by seminal plasma from infertile men with cytotoxic antibodies to autologous and/or control sperm. Seminal plasma from fertile men enhanced sperm survival. Cervical mucus from infertile women with antibodies to autoimmune husbands' sperm or to husbands' and control sperm inhibited sperm motion, whereas cervical mucus from infertile women without sperm antibodies and women with antibodies to control sperm failed to have any effect. It is concluded that cytotoxic sperm antibodies developed through exposure to sperm antigens in autoimmune infertile men decrease in vitro sperm survival and/or motility.

Antibodies↗
PubMed1986

Effect of exogenous histone H5 on integration of histone H1 in rat liver chromatin. Correlations with aberrant epsilon-N-methylation of histone H1.

Binding modes of histones H1 and H5, and their competition for chromatin-binding sites in rat liver nuclei, were correlated with aberrant N-methylation of H1 histone lysine residues, induced by chicken erythrocyte histone H5, in order to gain more insight into the integration of lysine-rich histones in chromatin. Addition of approx. 2.5 molecules of histone H5 per nucleosome to rat liver nuclei increases the ratio of total basic residues in histones to DNA nucleotides (BR/NT) in the nuclear chromatin from 1.0 to 1.5. At this concentration, approx. 0.7 molecule of histone H5 is bound per nucleosome, and there is no displacement of histone H1 from the nuclear chromatin. If S-adenosyl[Me-3H]methionine is present in the incubation mixture, the aberrant incorporation of labeled methyl groups into histone H1 reaches a maximum at this concentration of histone H5. The radioactivity present in histone H1 from nuclei incubated with labeled AdoMet at a total BR/NT ratio of 1.5: resides mainly in a histone H1 subfraction tentatively identified by Bio-Rex 70 chromatography and acrylamide gel electrophoresis as histone H1c; presents as a single spot upon peptide mapping of tryptic hydrolysates by means of two-dimensional thin-layer chromatography; and elutes in the position of mono-N-methyllysine upon ion-exchange chromatography of histone H1 hydrolysates. Upon further increase of the BR/NT ratio, the following changes are produced: a gradual decrease in radioactive methyl uptake into histone H1; a gradual displacement of histone H1 from the chromatin; increased binding of histone H5 in chromatin, up to a maximum of 3.4 residues per nucleosome; and a slowly increasing uptake of label into histone H5. The combined data from histone H1/H5 binding and histone H1 methylation studies suggest that upon addition of exogenous histone H5 to rat liver nuclei the binding of two lysine-rich histones per nucleosome plays a significant role in the induction of specific changes in chromatin structure, which in vivo may have important functional implications in terms of chromatin condensation and suppression of transcription.

Animals↗
PubMed1986

Motion characteristics of spermatozoa from men with cytotoxic sperm antibodies.

Semen samples from 55 fertile nonautoimmune and 44 infertile sperm autoimmune men were evaluated by computerized sperm cell motion analysis. Sperm counts (mean +/- SEM, 59.6 +/- 10.3 X 10(6) per ml), motility (39.0 +/- 4.6%), mean swimming speed (micron/sec, 26.5 +/- 0.9), mean linearity (straight line distance of the cell track divided by the actual track length and multiplied by 10, 6.5 +/- 0.2), and motility index (% motility X mean speed, 10.7 +/- 1.4) in 23 men with significant titers of cytotoxic sperm antibodies in their serum and seminal plasma were less (p less than 0.0001) than those in the fertile controls. However, these parameters were comparable in 18 men with sperm antibodies in their seminal plasma but not in their serum, and the control group. Infertile men with serum cytotoxic sperm antibodies had more sperm cells swimming at 11-30 micron/sec, and fewer moving at 31 micron or higher; this was in contrast to results obtained from fertile men (p less than 0.05). The percentages of sperm cells moving at 21-30 micron/sec were increased, while those moving at 51-60 microns/sec were decreased in men with seminal plasma sperm antibodies, versus controls. Spermatozoa with low linearities (less than or equal to 6) were higher (p less than 0.05) in men with serum and seminal plasma cytotoxic sperm antibodies than in the fertile group.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies↗
PubMed1985

Demographic analysis of childhood pedestrian injuries.

Factors in a child's living environment and socioeconomic background that contribute to the risk of pedestrian injury were studied. In 1982, in the city of Memphis, there were 210 pedestrian injuries among children aged 0 to 14 years, a rate of 138/100,000 children. The injured child was most often male, with mean age of 7.3 years; the child was usually struck while crossing the street between intersections, most commonly during the hours from 2 to 7 PM. Pedestrian injuries occurred in 81 of the 142 census tracts in the city. Compared with census tracts without reported injuries, these tracts had twice the percentage of nonwhite population, lower household incomes, more children living in female-headed households, more families living below the poverty level, and greater household crowding (all differences significant at P less than .01). The single variable of crowded housing per acre best predicted the number of injuries per acre in multiple regression analysis. A group of children who are at high risk of pedestrian injury through increased exposure in the environment was identified. As with many other types of injuries, modification of external factors--in this case, traffic engineering modifications--seems to be the most practical solution.

Accident Prevention↗
PubMed1984

Effects of exercise using industrial respirators.

Respirators (respiratory personal protective devices), used for protection against occupational toxic exposures, may impose flow resistance and dead space respiratory loading. Effects of exercise level, a 300 mL deadspace and single respirator cartridge inspiratory load were determined in ten healthy volunteers. Subjects tended to limit peak work rate (pressure generated and pressure X flow) and to prolong the inspiratory portion of the respiratory cycle due to respirator use. O2 consumption and heart rate were not significantly affected. The qualitative response was not affected by exercise level. During submaximal exercise, normal subjects did not reach their compensation limits for the variables studied.

Heart Rate↗
PubMed1982

Physiologic effects of respirator dead space and resistance loading.

Air-purifying respirators impose several loads on breathing. The effects of inspiratory flow resistance, respiratory dead space such as that of a full-face mask, and moderate exercise and maximal exercise were assessed alone and in combination in nine normal volunteers. There were significant effects on respiratory timing variables (e.g., inspiratory time, inspiratory: expiratory time ratio), peak mouth pressure and peak inspiratory flow rate. Only minimal effects on heart rate were noted. These results suggest that prospective workers who must utilize respirators should be observed during exercise as well as at rest and that a respirator dead space and inspiratory resistance should not produce a significant heart rate change but should lead to adaptation of the inspiratory: expiratory time ratio. Workers who show atypical responses should be assessed particularly carefully.

Adult↗
PubMed1981

Fast-atom-bombardment mass spectra of enkephalins.

The positive- and negative-ion mass spectra of [methionine]enkephalin and [leucine]enkephalin have been obtained by using a fast-atom-bombardment source described previously by Barber, Bordoli, Sedgwick & Tyler [(1981) J. Chem. Soc. Chem. Commun., in the press]. This technique has allowed the spectra to be obtained without conversion of the enkephalins into volatile derivatives. The fast-atom-bombardment spectra show good pseudo-molecular-ion sensitivity and fragmentation that can be interpreted on the basis of the known molecular structure.

Anions↗