PubMed Health⌕ Search

Biomedical subjects

R J Aitken

Publications and source records attributed to R J Aitken.

At least 145 records · Page 8Linked to original sources
PubMed1989

Transmembrane migration technique: reexamination of its usefulness in sperm motility assessments.

A study was carried out using time-exposure photomicrography to investigate the potential usefulness of the transmembrane migration technique in the assessment of drug effects on human sperm motility. Significant but weak correlations were evident between the transmembrane migration ratio (TMMR%) and both % motility (r = 0.43; p less than 0.05) and the amplitude of lateral sperm head displacement (r = 0.40; p less than 0.05). However, no significant correlations were evident between TMMR% and the concentration of motile spermatozoa, mean path velocity, or frequency of sperm head rotation. Exposure to 2.5 mM 2-deoxyadenosine caused significant increases in % motility, mean path velocity, and frequency of sperm head rotation, with no concomitant rise in TMMR%, while 5.0 mM caffeine caused significant elevations in both TMMR% and in % motile cells. It is concluded that the transmembrane migration technique is a relatively insensitive method for detecting subtle but important changes in the movement characteristics of human spermatozoa.

Caffeine↗
PubMed1989

Inflammatory bowel disease and male infertility: effects of sulfasalazine and 5-aminosalicylic acid on sperm-fertilizing capacity and reactive oxygen species generation.

To investigate the mechanism of the antifertility action of sulfasalazine, we prospectively measured sperm density, motility, hamster oocyte penetration capacity, and reactive oxygen species production in six men with inflammatory bowel disease being treated with sulfasalazine and 8 and 16 weeks after changing to 5-aminosalicylic acid (5-ASA). An improvement was observed after changing to 5-ASA in those with poor (n = 3), but not in those with normal (n = 3), sperm function on sulfasalazine. There was no correlation between reactive oxygen species production or acetylator phenotype with egg penetration capacity, sperm motility, or sperm density. We conclude that the mechanism of impairment and recovery of sperm function on and off sulfasalazine treatment is not related to an excess in reactive oxygen species.

Adult↗
PubMed1989

Suppression of sperm function by depot medroxyprogesterone acetate and testosterone enanthate in steroid male contraception.

Ten normal men were given three monthly intramuscular injections of 200 mg of depot medroxyprogesterone acetate (MPA) and 250 mg of testosterone (T) enanthate. Six men became azoospermic, while four remained oligozoospermic, with a mean sperm density of 1.5 +/- 0.3 standard error of the mean million/ml. Zona-free hamster oocyte penetration was abolished in all oligozoospermic samples at the end of treatment. Twenty of the 21 oligozoospermic samples yielding at least 0.6 to 5.0 million motile spermatozoa showed a complete absence of oocyte penetration. Semen parameters returned to normal, although some took up to 12 months. These findings demonstrated an antifertility action of MPA and T enanthate on the functional capacity of residual spermatozoa and support the view that extreme oligozoospermia may be a tenable target for reversible steroid male contraception.

Adult↗
PubMed1989

Generation of reactive oxygen species, lipid peroxidation, and human sperm function.

Recent studies have demonstrated that human spermatozoa are capable of generating reactive oxygen species and that this activity is significantly accelerated in cases of defective sperm function. In view of the pivotal role played by lipid peroxidation in mediating free radical damage to cells, we have examined the relationships between reactive oxygen species production, lipid peroxidation, and the functional competence of human spermatozoa. Using malondialdehyde production in the presence of ferrous ion promoter as an index of lipid peroxidation, we have shown that lipid peroxidation is significantly accelerated in populations of defective spermatozoa exhibiting high levels of reactive oxygen species production or in normal cells stimulated to produce oxygen radicals by the ionophore, A23187. The functional consequences of lipid peroxidation included a dose-dependent reduction in the ability of human spermatozoa to exhibit sperm oocyte-fusion, which could be reversed by the inclusion of a chain-breaking antioxidant, alpha-tocopherol. Low levels of lipid peroxidation also had a slight enhancing effect on the generation of reactive oxygen species in response to ionophore, without influencing the steady-state activity. At higher levels of lipid peroxidation, both the basal level of reactive oxygen species production and the response to A23187 were significantly diminished. In contrast, lipid peroxidation had a highly significant, enhancing effect on the ability of human spermatozoa to bind to both homologous and heterologous zonae pellucidae via mechanisms that could again be reversed by alpha-tocopherol. These results are consistent with a causative role for lipid peroxidation in the etiology of defective sperm function and also suggest a possible physiological role for the reactive oxygen species generated by human spermatozoa in mediating sperm-zona interaction.

Animals↗
PubMed1989

Influence of epididymal maturation on cyclic AMP levels in hamster spermatozoa.

Whilst in their native epididymal fluid, sperm from the caput epididymis of the rat and hamster contain significantly (P less than 0.01) greater amounts of cAMP than do sperm from the cauda epididymis. The cAMP levels in both cell types from these species underwent a rapid increase concomitant with dilution to a density of 20 x 10(6)/ml. Further analyses in the hamster indicated that this increase was calcium-dependent, and could be enhanced by treatment with the calmodulin antagonist, calmidazolium. Dilution of hamster sperm to a concentration of 1 x 10(6)/ml was not associated with a rapid rise in cAMP levels. This effect was shown to be due to the dilution of a component in epididymal plasma. When incubated at this lower density, the cAMP content of hamster caput sperm remained low over a 3 h period, whilst similarly treated caudal sperm exhibited a progressive rise in cAMP levels. Thus, in contrast to other species, cAMP does not appear to play a pivotal role in acquisition of the capacity for movement during epididymal maturation in the rat and hamster. However, this nucleotide may be involved in the post-ejaculatory modifications of motility which accompany the terminal stages of capacitation.

Animals↗
PubMed1989

Subcuticular skin closure following minor breast biopsy: Prolene is superior to polydioxanone (PDS)

The aim of this study was to determine whether a subcuticular absorbable suture (polydioxanone acid, PDS, Ethicon, UK) was superior to a subcuticular non-absorbable suture (Prolene, Ethicon, UK) for day-case breast biopsy performed under local anaesthesia. After breast biopsy, the type of subcuticular suture to be used was randomized in 100 patients. In all other respects the surgery and written postoperative instructions were similar for the group. Patients were reviewed over two visits by one independent observer who was unaware of the suture utilized (median 10 days and 52 days after surgery). Three patients had incomplete documentation and four patients failed to attend for either visit: thus 47 and 46 patients in the Prolene and PDS groups, respectively, were assessed. There was no difference between the Prolene and PDS groups, respectively, in the median interval to either the first shower or removal of the original plaster. There were three wound infections (one with Prolene, two with PDS). At the first visit three patients in the Prolene group had their incision uncovered, compared to 20 patients in the PDS group. In the PDS group a buried knot eroded through the incision in eight patients (17%). In this study the expected advantages of an absorbable suture were not confirmed.

Adult↗
PubMed1988

Analysis of calmodulin acceptor proteins and the influence of calmodulin antagonists on human spermatozoa.

The possible role of calmodulin in regulating a number of calcium-dependent functions exhibited by human spermatozoa was investigated by using the antagonists trifluoperazine and calmidazolium. At high doses both antagonists inhibited the motility of human spermatozoa and induced a concomitant rise in [Ca2+]i and a decline in cAMP. Lower doses of these antagonists, particularly calmidazolium, suppressed the ability of human spermatozoa to generate reactive oxygen species and exhibit sperm-oocyte fusion, without influencing [Ca2+]i, cAMP, or motility. This inhibition of sperm-oocyte fusion was effective even if the spermatozoa were subsequently exposed to A23187, suggesting that calmodulin may regulate this aspect of human sperm function at a point downstream from calcium influx. Both radiolabelling and affinity chromatography techniques were used to detect a number of calcium-dependent and calcium-independent calmodulin acceptor proteins in the human spermatozoon. The major calcium-dependent acceptor proteins exhibited Mr values of 32,000 and 22,000-27,000, respectively, and did not appear to be associated with the sperm plasma membrane.

Calcium↗
PubMed1988

Assessment of sperm function for IVF.

Recent advances in our ability to understand and manipulate the fundamental mechanisms regulating human sperm function have led to the development of a new generation of diagnostic techniques, designed to give objective data on the functional competence of human spermatozoa. These techniques have proved to be of value in predicting the ability of patients' spermatozoa to fertilize the human ovum in vitro and in the evaluation of techniques and reagents of relevance to the therapeutic application of IVF, including sperm preparation protocols and reagents for the artificial enhancement of sperm function. Moreover the use of sperm function tests has shed light on the biochemical nature of the lesions present in the spermatozoa of subfertile males, with particular emphasis on the role played by reactive oxygen species. As a result of such studies we are now in a position to adopt a more rational approach to the development of modified IVF protocols for the treatment of male infertility.

Acrosome↗
PubMed1988

Influence of antisperm antibodies on human sperm function.

Antisperm antibodies have been found in about 8% of men with infertility and in 60 to 80% of patients following vasectomy. In order to investigate the way antibodies influence sperm function we studied serum and seminal plasma from patients with infertility (n = 61) or undergoing vasovasostomy (n = 25). These antisera were characterised to determine their TAT titre, the nature of the target antigens and their capacity to interfere directly with fertilisation. The results indicate that antibodies from both groups of patients exhibit a capacity to stimulate or suppress sperm/oocyte fusion. The proportion of samples showing stimulatory activity was higher (50%) in the vasovasostomised population than in patients with infertility (21%). The remainder of the antisera suppressed sperm/oocyte fusion. There was no correlation between the titre of antisperm antibodies and their capacity to influence sperm function, indicating that it is the nature of the target antigens which is of significance rather than the antibody concentration. Western blot analysis indicated that these antisera targeted a group of sperm surface antigens with molecular weights of 30kD (35,45,66,90 and 115kD). Monoclonal antibodies are now being prepared in order to determine which of these specific components are involved in the suppression of sperm function.

Antibodies↗
PubMed1988

Prognostic significance of the zona-free hamster egg test.

Hamster tests were performed on sperm samples submitted by 111 men attending a fertility clinic. The method used involved exposure of the sperm to an ionophore to stimulate capacitation as this has been shown to give better egg penetration rates. The men were followed up for a total of 166 couple years and note was made of any pregnancies. At the time of their initial assessment most of the men had poor sperm measurements using conventional methods of semen analysis. The hamster test results gave no additional prognostic information to that already known from the duration of involuntary infertility reported by the couple at their first clinic visit and sperm motility and concentration determined by conventional semen analysis. It was concluded that the hamster test was not useful in this situation.

Animals↗
PubMed1988

Contraceptive potential of antibodies to the zona pellucida.

The notion of a contraceptive vaccine based on gamete-specific surface antigens was first proposed over a decade ago, as the result of in-vitro and in-vivo studies, and in recent years has been the subject of intensive research. In particular, the zona pellucida has attracted much attention as a potential target for immunological intervention in the fertilization process. Such is the rapidly-expanding nature of research into the biochemical and biological characterization of this structure, that a review of the implications for the development of a contraceptive vaccine seems timely.

Antigens, Surface↗
PubMed1987

Analysis of the biological properties of antibodies raised against intact and deglycosylated porcine zonae pellucidae.

Zonae pellucidae (ZP) were isolated from 1,500 porcine ovaries and heat solubilized to generate approximately 15 mg ZP glycoprotein. Analysis of this material by isoelectric focusing, one-dimensional electrophoresis, and gas chromatography indicated the presence of a major glycoprotein species that exhibited considerable microheterogeneity with respect to its charge (pI 7.5-3.5) and molecular mass (45-85 kDa) and that contained 39.6% carbohydrate, predominantly N-acetylglucosamine. Chemical deglycosylation of porcine ZP using trifluoromethanesulphonic acid (TFMS) resulted in the production of five discrete protein bands on one-dimensional sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE) with molecular masses of 66, 52, 36, 32, and 16 kDa. Antisera raised in rabbits and marmosets to ZP and/or deglycosylated ZP (DGZP) were used in immunoblotting experiments to demonstrate the retention of immunogenicity by DGZP and the cross-reactivity of the antisera with their heterologous antigen. These studies indicated that antisera that were capable of inhibiting the fertility of primates in vivo and the penetration of the human ZP in vitro reacted preferentially with 3 of the 5 products of deglycosylation, with molecular masses of 66, 52, and 36 kDa. Anti-DGZP antibodies were also shown to interact with intact porcine and human ZP and, with the latter, to block the ability of human spermatozoa to both bind to and penetrate this structure.

Animals↗
PubMed1987

Polyclonal antibodies to a 32-kDa deglycosylated polypeptide from porcine zonae pellucidae will prevent human gamete interaction in vitro.

The major deglycosylated polypeptides of the porcine zona pellucida (ZP), with molecular masses of 66, 52, 36, and 32 kDa, were purified to homogeneity with one-dimensional sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE). Immunofluorescence studies demonstrated that antibodies to the DGZP fraction, and the 66- and 32-kDa polypeptides, bound predominantly to the outer ZP; however, only the first two of these antisera formed an immunoprecipitate around the outer human ZP. In immunoblotting experiments using polyclonal antisera raised to these molecules all four polypeptides exhibited cross-reactivity with each other and their parental glycoprotein families (ZP 1-4). In addition, the antisera were tested in an in vitro human gamete bioassay to determine their contraceptive potential; antibodies to the 32-kDa deglycosylated polypeptide inhibited human gamete interaction to the greatest extent, 5.3% (+/- 1.2%), relative to a control value of 100%.

Animals↗