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Biomedical subjects

S S David

Publications and source records attributed to S S David.

18 recordsLinked to original sources
PubMed1992

Relation between antisperm antibodies and the rate of fertilization of human oocytes in vitro.

To clarify further the role of antisperm antibodies in in vitro fertilization, the occurrence of antisperm antibodies on ejaculated sperm and in sera was determined by the immunobead binding assay in 67 couples after an unsuccessful in vitro fertilization cycle. Antisperm antibodies in maternal sera were associated with a failure of oocyte fertilization (P less than 0.02) or with fertilization of only 9-19% of the oocytes (P less than 0.01) in vitro. Antisperm antibodies were detected in sera from 13 of 24 women (54.2%) where no fertilization occurred, 9 of 14 women (64.3%) where less than 20% of the oocytes fertilized, and 3 of 19 women (15.8%) where greater than 40% of the oocytes fertilized. Antisperm antibodies in these sera were mostly IgG and directed against the sperm tail. Antibodies on the surface of ejaculated motile sperm were also associated with a low (9-19%) fertilization rate (P less than 0.01). Sperm-bound antibodies were detected in 2 of 24 men (8.3%) where no fertilization occurred, 5 of 14 men (35.7%) where less than 20% of the oocytes fertilized, and 0 of 19 men where fertilization was greater than 40%. Sperm-bound antibodies were mainly IgA and were tail-directed. Antisperm antibodies in sera of males were not related to the rate of fertilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

A case of primary mesenteric fibromatosis.

A case of primary mesenteric fibromatosis is reported and the current modalities of therapy are discussed. Surgery is the primary mode of treatment. Other modalities should be reserved for gross local residual disease and for unresectable recurrence.

Adult↗
PubMed1992

Acral lentiginous melanoma in situ.

Acral lentiginous melanoma in situ is a rare entity in the broad spectrum of melanoma. Although acral lentiginous melanoma is not uncommon, the in situ variant seems to have been reported only twice in the literature. An additional case is described.

Chronic Disease↗
PubMed1991

Electrochemical properties of the diiron core of uteroferrin and its anion complexes.

The reduction potentials (Em) of the purple acid phosphatase from porcine uterus, uteroferrin (Uf), and its phosphate, arsenate, and molybdate complexes were determined by coulometric methods at various pH values. The midpoint potential of Uf at the pH value for optimal enzyme activity (pH 5) was found to be +367 mV versus a normal hydrogen electrode (NHE), while at pH 6.01 Uf exhibits a reduction potential of +306 mV. At pH 6.01 molybdate was found to shift the potential of Uf more positive by 192 mV, while phosphate and arsenate shift the potential of Uf more negative by 193 and 89 mV, respectively. These shifts are consistent with the different susceptibilities of Uf to aerobic oxidation in the presence of these anions. Comparison of the reduction potential of Uf at pH 7.0 with those reported for other dinuclear non-heme iron enzymes and various (mu-oxo)diiron model complexes suggest that the potential of Uf is too positive to be consistent with a mu-oxo-bridge in Ufo. The pH dependence of the reduction potentials of Uf (60 mV/pH unit) and the fact that the electron transfer rate increases with decreasing pH indicate a concomitant participation of a proton during the oxidation-reduction process. This process was assigned to the protonation of a terminally bound hydroxide ligand at the Fe(II) center upon reduction of Ufo. Structural implications provided by the electrochemical data indicate that molybdate affects the dinuclear core in a manner that differs from that of phosphate and arsenate. This observation is consistent with previous spectroscopic and biochemical studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1988

Magnetization and electron paramagnetic resonance studies of reduced uteroferrin and its "EPR-silent" phosphate complex.

The exchange coupling of reduced uteroferrin has been measured (19.8(5) cm-1 S1.S2) using recently developed techniques for studying metalloprotein magnetization. A spin Hamiltonian describing the coupled binuclear Fe(II).Fe(III) center has been used to fit the low and high field magnetization data, the EPR g values, and the highly anisotropic effective hyperfine tensor of the ferric site. The exchange coupling of the phosphate complex of reduced uteroferrin has also been measured (6.0(5) cm-1 S1.S2) using the same techniques. The smaller exchange coupling of the phosphate complex is comparable with the zero field splittings of the iron sites. This results in increased sensitivity of the system g values (found by calculation from the spin Hamiltonian) to variations of the zero field splitting parameters arising from heterogeneities in the protein microenvironment. Consequently, there is a very significant (9-fold) increase in the "effective g strain" of the system compared to the situation in the absence of phosphate. This, together with the larger g anisotropy (g = (1.06, 1.51, 2.27)), gives rise to an EPR signal for the phosphate complex of reduced uteroferrin which is extremely broad and difficult to detect but which has now been identified for the first time.

Acid Phosphatase↗
PubMed1988

Heterogeneity of antigenic determinants on human spermatozoa: relevance to antisperm antibody testing in infertile couples.

Sera from 1074 male and 947 female partners of infertile marriages were tested by enzyme-linked immunosorbent assay for antibodies to motile sperm purified from ejaculates of the male partners or a donor. In men, 9.2% of the sera were positive for immunoglobulin A, 7.9% for immunoglobulin G, and 5.1% for immunoglobulin M antibodies to their own sperm. In women, immunoglobulin M antibodies to the husband's sperm predominated (10.1%), with immunoglobulins G (8.3%) and A (5.9%) following. Differences between men and women in the incidence of immunoglobulin A (p less than 0.01) and M (p less than 0.005) antibodies were significant. In both sexes only about two thirds of the antibody-positive sera remained positive when donor sperm was substituted for partners' sperm in the assay. The decreased occurrences of antisperm immunoglobulins A (p less than 0.025) and G (p less than 0.01) in men and of immunoglobulins G (p less than 0.025) and M (p less than 0.01) in women were significant. Incubation of donor sperm in the husband's cell-free seminal fluid before analysis led to the acquisition of sperm reactivity with husband-specific antisperm antibodies in only one of eight women. Women with husband-specific antisperm antibodies also exhibited differences in their cell-mediated immune responses to sperm from various men. Thus sperm from different individuals vary in their ability to react with the immune system of sperm-sensitized men or women.

Antibodies↗
PubMed1988

Effect of sperm antibodies on pregnancy outcome in a subfertile population.

The relationship between sperm antibodies, conception, and miscarriage was examined in 109 infertile couples. Antibodies present on the surface of husbands' ejaculated sperm and antibodies in husbands' or wives' sera that reacted with a purified population of the husbands' motile spermatozoa were detected by an enzyme-linked immunosorbent assay. During an 18-month period, conception occurred in 33 (30.3%) of the couples; 16 (14.7%) women subsequently suffered a spontaneous miscarriage during the first trimester, whereas 17 (15.6%) women maintained their pregnancies past this time period. Antisperm antibodies were present in sera from only two of 17 (11.8%) women with successful pregnancies, whereas seven of 16 (43.8%) women who miscarried and 29 of 76 (38.2%) who did not conceive had these antibodies in their sera. IgG (22.4%) and IgM (21.1%) antisperm antibodies predominated in sera of women who did not conceive, whereas IgA (37.5%) and IgG (37.5%) antibodies were most prevalent in sera of women with miscarriages. In men, the presence of antisperm antibodies in sera was unrelated to fertility. However, there was a correlation between sperm surface antibodies and an inability to conceive. IgG was identified on ejaculated spermatozoa from eight of 76 (10.5%) men whose wives failed to conceive and in none of 33 men whose wives conceived. Similarly, IgA was present on spermatozoa from 16 (21.1%) infertile and two (6.1%) fertile men. Thus antisperm antibodies in female sera and on ejaculated spermatozoa were associated with a failure to conceive and first-trimester miscarriage.

Antibodies↗
PubMed1986

Peripheral vision and the aetiology of child pedestrian accidents.

Three experiments examined whether age and sex differences in pedestrian accidents might be partly attributable to differences in the visual perception of peripheral stimuli. Primary schoolchildren and adults responded individually to the presentation of lights at retinal eccentricities of 2 degrees, 20 degrees and 40 degrees. Experiments 1 and 2 measured reaction times and Expt 3 measured subjects' expectations of foveal and peripheral events. There were no age or sex differences in expectations. Lights were detected fastest in the 20-40 degrees range. Movement times were not variable across eccentricities. As expected, adults' and 11-year-olds' detections were faster than eight- and six-year-olds'. A case is made for more problem-analytic and multi-theoretical research in the area of the child pedestrian accidents.

Accidents, Traffic↗
PubMed1986

Peripheral vision and child pedestrian accidents.

In both adults and children, peripheral vision is poorer than foveal vision, but there is evidence that detection in peripheral vision is relatively poorer in children than it is in adults. That may contribute to the particularly high pedestrian accident rates of children. Two laboratory experiments investigated peripheral vision in men and women and in boys and girls aged 7, 9 and 11. Using an array of stationary lights, Expt 1 examined reactions to apparent movement (the phi phenomenon) in mid and extreme periphery; and, using film sequences of a moving car, Expt 2 included a comparison of foveal and peripheral fields. Overall there was little evidence to support the hypothesis that children have poorer peripheral vision than adults relative to their foveal vision. Nonetheless there were some experimental differences: in Expt 1, 7-year-olds made fewer detections, particularly in the extreme periphery; and, in both experiments, detections tended to be slower. The relatively complex car movements in Expt 2 were detected faster in foveal than peripheral vision. There were no sex differences. Children detected more movements on the left. In Expt 2 these detections were faster, and children made relatively more simulated road crossings when the car approached from the left (all adults 'crossed' in all trials).

Accidents, Traffic↗
PubMed1979

A synthetic steroid (R2323) as a once-a-week oral contraceptive.

Five milligrams of the steroid R2323 (13 beta-ethyl-17 alpha-ethynyl-17-hydroxygona-4,9,11-trien-3-one (R2323) were administered orally once weekly to 28 subjects for a total of 138 treatment cycles. No pregnancies occurred. The predominant side effects were irregular vaginal bleeding, headache, weight gain, and acne. Administration of the drug was stopped by the investigator in four patients (14%) because of the onset of headaches. Four patients discontinued the drug for other reasons. In 8 of 26 subjects (31%), endometrial biopsy in the third treatment cycle showed secretory endometrium. This suggests a variable central suppression with the 5-mg dose schedule. Patients were enthusiastic about the once-weekly oral administration. This contraceptive may be useful in a select group of women.

Adolescent↗
PubMed1977

Pelvic endometriosis: infertility and pelvic pain.

A multifactorial approach was used by the authors to analyze data from 119 women with endometriosis and infertility. Conservative surgical procedures afforded a mean pregnancy rate of 37.7 per cent for those women with significant disease. Only 6.7 per cent became pregnant when the proposed surgery was declined. There was an inverse relationship in severity of endometriotic involvement and pregnancy rate. The mean pregnancy rate among 17 patients with minimal disease for whom surgery was discouraged was 64.7 per cent; all pregnancies occurred within the first 2 years of follow-up. Relief of pelvic pain was dramatic, especially following presacral neurectomy. Laparoscopic selection of cases further reinforces the importance of grading severity of endometriosis prior to embarking on restorative surgery. Presacral neurectomy, despite reinforcement of pain relief, did not appear to contribute significantly to the occurrence of pregnancy.

Adult↗
PubMedDate not supplied

Concomitants of atherosclerotic carotid artery stenosis.

To identify metabolic and other concomitants of a single important type of atherosclerotic cerebrovascular disease, 75 patients with angiographically and surgically proven internal carotid stenosis were compared with age and sex matched control subjects with respect to plasma cholesterol, triglycerides and glucose. They were also compared for blood pressure, cigarette smoking, evidence of ischemic heart disease, peripheral vascular disease and for a family history of these diseases. Patients with carotid stenosis had higher systolic and diastolic blood pressures and higher plasma cholesterol and triglyceride concentrations than the control groups. They had, as well, a far greater likelihood of being cigarette smokers and a greater likelihood of having diabetes mellitus and previous evidence of coronary and peripheral vascular disease. Patients with carotid stenosis were far more likely to have 2 or more of these common concomitants of atherosclerosis than were the control subjects. The data suggest that the precursors of carotid stenosis are similar to those of coronary atherosclerosis and raise the hope that modification of these factors may decrease the incidence of this highly prevalent form of cerebrovascular disease.

Adult↗