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Biomedical subjects

S M Walker

Publications and source records attributed to S M Walker.

At least 91 records · Page 5Linked to original sources
PubMed1984

Antisperm antibodies and male infertility.

Two hundred males attending a fertility clinic and 65 men who had fathered one or more children were screened for sperm antibodies using sperm agglutination and immobilisation tests. The incidence of sperm antibodies was significantly higher in the former group. Agglutinin and immobilisin were not related to sperm concentration, morphology, ejaculate volume, seminal plasma zinc, magnesium, acid phosphatase and fructose. However, sperm motility and viability were significantly reduced in the presence of sperm antibodies. There appeared to be no relationship between the presence of antisperm antibodies and Mycoplasma, aerobic or anaerobic organisms. There was a positive correlation between agglutinating and immobilising antibodies in serum and seminal plasma. This study suggests that sperm antibodies at a significant titre may lower male fertility.

Agglutination Tests↗
PubMed1984

Longitudinal studies of luteal function by salivary progesterone determinations.

A 'normal range' for salivary progesterone concentrations has been established using data derived from women who were menstruating regularly and in whom dating of the cycle by accepted criteria was possible. Since these values are in agreement with those in the first 9 days of conception cycles and with those in cycles in which ovulation was confirmed by ultrasonography, they provide a reliable index of progesterone output compatible with fertility. Measurement of daily salivary progesterone values in subfertile women for time spans exceeding 3 months allowed accurate assessment of base-line ovarian activity and of the response to ovulation-induction therapy. Salivary sampling, by allowing collection of frequent samples with a minimum of time, stress and inconvenience, is ideally suited to longitudinal studies of ovarian activity. This sampling regimen is also applicable to the monitoring of progesterone output throughout pregnancy.

Adolescent↗
PubMed1983

The role of mycoplasmas in reproduction.

A study of the incidence of genital tract mycoplasmas in couples attending an infertility clinic and in a group of pregnant women showed that the frequency of isolation was significantly higher in the infertile group (P less than 0.001). In pregnancy, if mycoplasmas were isolated at the first prenatal visit, these organisms were harbored throughout pregnancy. Five percent of the women, however, developed the infection during pregnancy. No relationship was observed of female genital mycoplasmas with prematurity or babies small for gestational age. Treatment with doxycycline (Vibramycin, Pfizer Ltd., Sandwich, Kent, UK) was effective in eradicating mycoplasmas in 91% of couples, but the subsequent pregnancy rates in treated and untreated groups were similar. It appears that mycoplasmas are implicated neither in the etiology of reproductive failure nor in a poor pregnancy outcome.

Doxycycline↗
PubMed1983

Infertility.

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Female↗
PubMed1982

Enhanced resistance to Nocardia brasiliensis infection in mice depleted of antigen-specific B cells.

This study deals with the roles of T and B cells in Nocardia brasiliensis infection in mice. Nocardia injected into the animals' footpads caused inflammatory responses and mycetomas in situ, resulting in granulomatous lesions of subcutaneous tissues and eventual bone destruction. These clinical features resemble those of humans infected with Nocardia. The effect, if any, of antibody was studied by passively transferring anti-Nocardia serum into either immunologically normal or T-deficient infected mice. Such transfers had no protective function in either group. To the contrary, the antibody seemed to favor infection and worsen bone disease compared to that in mice not given antibody. Furthermore, passive transfer of the antibody along with injection of Nocardia coated with the antibody magnified the severity of subsequent symptoms. Although these experiments ruled out any role for antibody in protection from Nocardia, they did not directly prove T cell participation in such resistance. Therefore, the role of T cells during Nocardia infection was examined further by transferring spleen cells depleted of B lymphocytes bearing receptors for a Nocardia extract (NE). Lethally irradiated mice reconstituted with a population depleted of NE-specific B cells totally lacked the ability to form antibodies to NE; however, they mounted effective delayed-type hypersensitivity reactions and completely controlled their Nocardia infection, establishing the importance of cell-mediated immunity in halting this disease process.

Animals↗
PubMed1982

The immune response to homologous lens crystallin. I. Antibody production after lens injury.

Using a sensitive radioimmunoassay to homologous mouse alpha-crystallin, it was established that autoantibodies are produced to this self constituent in mice after rupture of the lens capsule by needling. Antibody to lens crystallin was detected within 4 days of lens rupture and persisted for 24 days, suggesting that these mice are not tolerant to alpha-crystallin at the B cell level. However, T cells from mice immunized with homologous crystallin cannot be stimulated to proliferate by either homologous or heterologous crystallin. On the other hand, lymphocytes from mice immunized with bovine alpha-crystallin can be stimulated to proliferate to bovine crystallin, but not to either unfractionated mouse crystallin (MC) or purified mouse alpha-crystallin. At the level of detection, therefore, T cells appear to be tolerant to homologous alpha-crystallin, but not to heterologous alpha-crystallin. LPS resulting from bacterial contamination after needling was ruled out as a necessity for antibody production because antibody to mouse alpha-crystallin was produced after sterile lens rupture with a laser. However, LPS and poly A:U did enhance the antibody response to alpha-crystallin. These data suggest that T cells, but not B cells, are tolerant to homologous crystallin and that antibody results from circumvention of specific helper T cell requirements for antibody synthesis. The implications of these findings for tolerance and autoimmune uveitis are discussed.

Animals↗
PubMed1981

In vitro tolerance induction of primed, IgD-negative murine spleen cells.

The above observations demonstrated induction of immunological tolerance in vitro in primed IgD-, IgG+ B cells. In these studies, addition of trinitrophenylated (TNP) turkey gammaglobulin (TGG) or TNP ovalbumin conjugates suppressed the secondary in vitro response in mice primed with TNP keyhole limpet hemocyanin (TNP-KLH). Suppression was not a reflection of a shift in kinetics of the antibody response, was not dependent on suppressor T cells, and could only be eliciate when conjugate was added within 4 h of addition of TNP-KLH moreover, preincubation of the primed spleen cells with TNP-TGG for 20 h at 37 degrees C, followed by extensive washing, was as effective in inhibiting the response to TNP-KLH as when TNP-TGG was present throughout the 5 d of culture, reflecting induction of a tolerant state. Amounts of conjugate in the concentration range that have been shown by others to tolerize immature or neonatal B cells or mature B cells that have been stripped of surface IgD were sufficient to induce tolerance. The target cells being tolerized did not bear IgD, as determined by B cell depletion and blocking procedures with anti IgD. Whether the lack of surface IgD on the primed cells contributed to the relative ease of tolerance induction was not established by these studies, but the advantages of using primed B cells to examine further the role of surface IgD in tolerance susceptibility was discussed.

Animals↗
PubMed1981

A new assay for the assessment of staphylococcal killing by human leucocytes.

A new method is described for investigating the killing of Staphylococcus aureus by human phagocytic cells. The radioassay is based on the principle that only viable bacteria synthesize DNA and incorporate [3H]thymidine. Phagocytes are incubated with bacteria and then disrupted by a single freeze-thaw cycle. The uptake of tritiated thymidine by the remaining organisms is a measure of the killing ability of the phagocytes. The technique is simple, sensitive, rapid and requires small volumes of blood. It can be semiautomated and uses equipment readily available in an immunology laboratory and is therefore suitable for routine investigations of leucocyte function. It is likely that the technique could form the basis for measuring kill by phagocytes of any rapidly dividing organism. A time course and a normal range have been evaluated for the bactericidal capacity of 26 normal individuals.

Blood Bactericidal Activity↗
PubMed1981

Use of Sputolysin form liquefaction of viscid human semen.

A comparative study evaluating the effect of different mucolytic agents on viscid semen and on sperm motility at successive time intervals was carried out. Sputolysin (dithiothreitol, Calbiochem Behring, 1978) was found to be most efficient in liquefying viscid semen and also in preserving sperm motility. The mean liquefaction times for Sputolysin, Alevaire (a mucolytic detergent), and alpha-amylase were found to be 10 minutes, 39 minutes, and 20 minutes, respectively. The rate of decline in sperm motility over an interval of 24 hours was found to be least with Sputolysin, followed in order by phosphate-buffered saline, alpha-amylase, control, and Alevaire. The adverse effect of Alevaire on sperm motility over successive time intervals was quite marked. A serial dilution study with Sputolysin showed that, at higher dilution (1:80), liquefaction time was prolonged (24 minutes), but it was still shorter than with Alevaire (39 minutes) and nearly the same as with alpha-amylase (20 minutes).

Dithiothreitol↗
PubMed1981

Prevalence and persistence of C1q binding activity in healthy subjects.

Samples of serum from 885 normal healthy blood donors were tested for the presence of soluble immune complex-like material by a solid-phase C1q binding assay. The majority of donors (93%) had low or undetectable levels of C1q binding activity in their sera, but 6% had levels that were clearly outside the normal distribution. When these individuals were retested after several weeks half of them still had elevated levels of C1q binding activity.

Antigen-Antibody Complex↗
PubMed1981

Bacterial lipopolysaccharide (endotoxin) interferes with the induction of tolerance and primes thymus-derived lymphocytes.

The injection of deaggregated human gamma-globulin (DHGG) into mice results in the establishment of specific immunologic unresponsiveness in T and B lymphocytes. However, the additional injection of bacterial lipopolysaccharide (LPS) 3 hr later converts the tolerogenic DHGG into an immunogen for both helper T and B cells. This generation of immunocompetence to HGG during interference with tolerance induction by LPS is demonstrated by both a primary plaque-forming cell response to DHGG + LPS and a secondary antibody response to a subsequent antigenic challenge. The secondary response to antigen stimulation in the B cells is, however, T cell dependent. Interference with tolerance induction in antigen-specific helper T cells can be demonstrated by challenge with the DNP-HGG hapten-carrier conjugate or by adoptive cell transfer with primed B cells and subsequent challenge with immunogenic HGG. Furthermore, helper T cells in the spleen and thymus become primed by DHGG + LPS as evidenced by their cooperation with primed B cells in the adoptive transfer assay. In addition to its interference with tolerance induction, LPS injected with either tolerogenic or immunogenic HGG also facilitates priming of helper T cells for the response to DNP-HGG. These data indicate that exposure of antigen-specific helper T and B cells to antigen alone results in the induction of tolerance, whereas induction of immunocompetence in these cells requires at least 2 signals, 1 provided by interaction with antigen and a 2nd delivered by a nonspecific stimulus similar to that provided by LPS in the present experiments.

Adjuvants, Immunologic↗
PubMed1981

Serum-mediated suppression of nonspecific B cell activation. I. Description of an inhibitory capacity in normal mouse serum and characterization of the inhibitory component.

Normal mouse serum (NMS) in relatively small amounts was demonstrated to inhibit in vitro splenic B cell activation by several B cell mitogens, polyclonal activators, and T-independent antigens. Proliferative and polyclonal responses elicited by bacterial endotoxin (ET), PPD, or Fc fragment of Ig were suppressed routinely 90% or greater when 0.5% homologous NMS was present in the culture medium. Similar suppression of T-independent antibody responses to TNP-ET and TNP-Ficoll was also observed. In contrast, activation by the T cell mitogen, Con A, and a T-dependent antigen response to SRBC was not inhibited by NMS. Suppression of B cell responses by NMS was not dependent on T cells. Preliminary characterization of NMS-In revealed a m.w. of approximately 200,000, an isoelectric point of 5, and solubility in 40% saturated ammonium sulfate. Both functionally and physically, NMS-In appears to be different from other currently relatively well characterized regulatory substances in serum. NMS-In was found in plasma as well as in serum, suggesting that NMS-In may function naturally in vivo to minimize nonspecific activation of B cells.

Animals↗