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R J Aitken

Publications and source records attributed to R J Aitken.

At least 19 recordsLinked to original sources
PubMed1992

Assessment of non-palpable mammographic abnormalities: comparison between screening and symptomatic clinics.

A retrospective study found that a breast screening clinic generated fewer localization biopsies for non-palpable mammographic abnormalities than a symptomatic clinic (3.36 versus 9.89 per 1000 mammograms, respectively) and that a greater proportion of such biopsies were malignant. This study determined the reason for this difference. There were 108 of 304 (35.5 per cent) and 17 of 130 (13.1 per cent) carcinomas in women attending the screening and breast clinics respectively (relative risk 2.72 (95 per cent confidence interval 1.70-4.34)). This difference was regardless of age. The characteristics of the mammographic abnormality, the Wolfe pattern, a family history of breast carcinoma, parity and age at first pregnancy were similar in both groups. Women attending the screening clinic were referred for localization biopsy after assessment by clinicians and radiologists at a joint clinic; there was no joint assessment for patients attending the breast clinic. The same staff attended both clinics, although the proportion of time spent at each varied. This study suggests that all women with a non-palpable mammographic abnormality should be reviewed at a joint assessment clinic before localization biopsy is recommended.

Biopsy↗
PubMed1992

Reactive oxygen species and human spermatozoa: analysis of the cellular mechanisms involved in luminol- and lucigenin-dependent chemiluminescence.

We have shown that human spermatozoa generate and release reactive oxygen species that can be detected by chemiluminescence techniques. Analysis of the cellular mechanisms responsible for this activity suggests that the probe, luminol, undergoes an intracellular dioxygenation reaction mediated by hydrogen peroxide and a sperm peroxidase located within the acrosome. Support for this model included the following observations: (1) the luminol-dependent signal could be suppressed with peroxidase inhibitors, phenylhydrazine and sodium azide; (2) this suppression could be reversed by the addition of an azide-insensitive peroxidase, horse radish peroxidase (HRP); (3) inhibition of intracellular superoxide dismutase (SOD) with potassium cyanide (KCN) suppressed the luminol signal; (4) peroxidase activity could be detected in purified populations of human spermatozoa with 3,3',5,5' tetramethylbenzidine (TMB); (5) this peroxidase was active at the pH prevailing within the acrosomal vesicle; and (6) peroxidase activity and luminol-dependent chemiluminescence were minimal in spermatozoa exhibiting a congenital absence of acrosomes. Human spermatozoa could also generate lucigenin-dependent chemiluminescent signals that could neither be suppressed with peroxidase inhibitors nor enhanced by the addition of peroxidase. However, these signals could be enhanced by suppression of intracellular SOD with KCN or inhibited by exogenous SOD, suggesting that lucigenin was responding to superoxide anion released into the extracellular space. The ability of chemiluminescent techniques to detect and discriminate the production of superoxide and hydrogen peroxide by spermatozoa should facilitate the further analysis of reactive oxygen species as mediators of normal and abnormal human sperm function.

Acridines↗
PubMed1992

Development of a technique for monitoring the contamination of human semen samples with leukocytes.

OBJECTIVE: To determine whether receptors for the N-formyl chemotactic peptide, FMLP, exist on the surface of human spermatozoa and regulate reactive oxygen species generation by these cells. DESIGN: Chemiluminescent analysis of reactive oxygen species generation by suspensions of human spermatozoa before and after removal of leukocytes using a magnetic cell separation technique. SETTING: Academic Research Institute. PATIENTS: Unselected male volunteers. RESULTS: Human sperm suspensions responded to FMLP and phorbol ester (PMA) with a burst of reactive oxygen species production. Autoradiographic analyses employing 3H FMLP and chemiluminescence studies involving the selective removal of leucocytes with anti-CD 45-coated magnetic beads demonstrated that the FMLP responses were because of leukocyte contamination. In contrast, reactive oxygen species production in response to PMA appeared to reflect the oxidant-generating capacity of both leukocytes and spermatozoa. CONCLUSION: The only cells present in the human ejaculate possessing detectable receptors for FMLP and capable of generating reactive oxygen species in response to this reagent come from the leukocyte population. Luminol-dependent, FMLP-induced, chemiluminescence provides a rational basis for monitoring the presence of leukocytes in suspensions of human spermatozoa.

Cell Fractionation↗
PubMed1992

Cloning and characterization of the human sperm receptor ligand ZP3: evidence for a second polymorphic allele with a different frequency in the Caucasian and Japanese populations.

The human ZP3 gene, encoding the glycoprotein responsible for sperm-egg recognition, has been cloned using mouse ZP3 DNA as a probe. Genomic and cDNA cloning revealed eight exons, spread over 18 kb, encoding a protein of 424 amino acids with a 67% homology to mouse and hamster ZP3. Southern blotting, gene cloning, and sequence analysis were used to show that ZP3 is not a single-copy gene and that the human genome contains a second polymorphic locus which, due to an extra G residue in exon 8, has the potential to encode a truncated protein of 372 amino acids. Direct sequence analysis of polymerase chain reaction-amplified exon 8 DNA of 56 individuals of various human populations revealed three different sequence patterns: one containing only ZP3-424-coding sequences and two containing ZP3-424- and ZP3-372-coding DNA. The distribution of these three sequence patterns is significantly different between the Caucasian and Japanese populations, as indicated by ZP3-372 allele frequencies of 69 and 21%, respectively. Isolation of ZP3-424 and ZP3-372 cDNAs suggests that both loci represent functional transcription units. Therefore, it is hypothesized that throughout the human population during oogenesis ZP3 is translated from mRNAs derived from two to four transcription units. Provided that ZP3-372 mRNA is translated in vivo, corresponding differences in ZP3-372 protein levels might have an impact on human zona pellucida composition.

Alleles↗
PubMed1992

Analysis of the contraceptive potential of antibodies against native and deglycosylated porcine ZP3 in vivo and in vitro.

We have undertaken a comparative analysis of the contraceptive activity of antibodies directed against the porcine sperm receptor zona pellucida antigen (ZP3) and its Mr = 32,000 polypeptide core (DGZP-32). The strategies employed for this analysis included the induction of active immunity in a primate, the common marmoset, and an in vitro fertilization protocol involving the use of viable human ova. In both experimental situations, antibodies against ZP3 were shown to exhibit contraceptive activity, leading respectively to the induction of long-term infertility in the primate model and to the complete inhibition of human fertilization in vitro. The in vivo studies also revealed that the induction of high titer antibodies against ZP3 was inevitably associated with the appearance of an ovarian pathology characterized by the progressive depletion of the primordial follicle pool within one to two years. This side effect could not be alleviated by the use of DGZP-32 as antigen since the induction of immunity against this polypeptide was also associated with the eventual appearance of an ovarian pathology identical to that observed with ZP3. Furthermore, the DGZP-32 peptide was less effective than ZP3 in inducing the formation of antibodies capable of inhibiting the fertilization of human ova in vitro. We conclude that significant problems remain with the use of deglycosylated zona peptides for the development of contraceptive vaccines and that their potential will not be realized until the epitopes responsible for the induction of infertility and the primordial follicle depletion have been identified and segregated.

Animals↗
PubMed1992

Enhanced detection of reactive oxygen species produced by human spermatozoa with 7-dimethyl amino-naphthalin-1, 2-dicarbonic acid hydrazide.

A new chemiluminescence technique has been assessed for the detection of reactive oxygen species generated by purified populations of human sperm. This revised protocol involves the use of horse-radish peroxidase (HRP) in combination with a luminol analogue, 7-dimethyl amino-naphthalin-1,2-dicarbonic acid hydrazide (DNDH), that exhibits two-three times the quantal efficiency of luminol itself. The chemiluminescent signal generated with these reagents was significantly (P less than 0.001) greater than that obtained with the conventional luminol-based methodology for both the steady-state situation and following stimulation of the sperm with PMA and A23187. Dose-response analyses indicated that the DNDH/HRP chemiluminescence system could give linear standard curves with hydrogen peroxide concentrations into the nmol l-1 range. In contrast, the exponential rise in chemiluminescence recorded with luminol was not observed until hydrogen peroxide concentrations exceeded 10 mumol l-1. It is concluded that the enhanced sensitivity of the DNDH/HRP system to low levels of hydrogen peroxide should facilitate the application of chemiluminescent techniques to the diagnosis of oxidative stress in cases of male infertility.

Fluorescent Dyes↗
PubMed1992

Residual sperm function in oligozoospermia induced by testosterone enanthate administered as a potential steroid male contraceptive.

To investigate the fertility of men who remain oligozoospermic despite sex steroid suppression, the in-vitro fertilizing capacity of residual spermatozoa was assessed in 30 men receiving intramuscular testosterone enanthate (TE). Spermatozoa were prepared by either Percoll or repetitive centrifugation/washing. Although the mean (+/- SEM) pretreatment zona-free hamster oocyte penetration (HOP) rates were similar (59.4 +/- 10.1 and 63.8 +/- 10.8%), following the induction of oligozoospermia the Percoll-prepared spermatozoa exhibited a penetration rate (26.9 +/- 10.2%) which was markedly greater than that obtained for sperm prepared by repetitive washing (0 +/- 0%). In addition, the partners of two men exhibiting a HOP test with Percoll-prepared spermatozoa, conceived despite a sperm concentration of 3 x 10(6) ml-1 and a negative HOP test with spermatozoa prepared by repetitive washing. These results suggest that Percoll preparation optimizes the assessment of in-vitro sperm function and that the fertility of men with TE-induced severe oligozoospermia is suppressed but not abolished.

Adult↗
PubMed1992

Differential contribution of leucocytes and spermatozoa to the generation of reactive oxygen species in the ejaculates of oligozoospermic patients and fertile donors.

Cells isolated from the ejaculates of a high proportion of patients exhibiting oligozoospermia are characterized by generation rates of reactive oxygen species that considerably exceed those obtained for the normal fertile population. The purpose of this study was to resolve the cellular source of this enhanced activity. Semen samples from a cohort of oligozoospermic patients and a group of fertile controls were fractionated on discontinuous Percoll gradients to generate three cell populations (0, 50 and 100%) of differing density. For each fraction, both the steady-state and the phorbol-ester-induced chemiluminescent signals were significantly (P less than 0.001) greater for the oligozoospermic samples than for the fertile controls. In the fertile donors, leucocytes comprised the major source of reactive oxygen species, particularly in the low-density Percoll fractions; in oligozoospermic patients, however, spermatozoa were identified as a second major source of reactive oxygen species. Particularly striking was an intense phorbol-ester-induced chemiluminescent signal generated by oligozoospermic spermatozoa, purified by passage through isotonic Percoll and free of leucocyte contamination, which was 167 times greater than the median signal generated by the corresponding fraction from the fertile controls (P less than 0.001). These results emphasize the importance of spermatozoa as a major source of reactive oxygen species in oligozoospermia and have implications for the diagnosis and treatment of this condition, as well as for the design of appropriate diagnostic strategies.

Cell Separation↗
PubMed1978

The hormonal control of implantation.

The hormonal control of implantation in mammalian species with and without embryonic diapause is described. In a majority of species displaying the obligate form of diapause the corpora lutea appear to exhibit a low level of steroidogenic activity throughout diapause, full luteal activity being resumed just before the initiation of implantation. Fluctuations in the plasma levels of oestrogen and progesterone during diapause may serve to prime the uterus for implantation. In species exhibiting the facultative form of diapause, such as the rat and mouse, both progesterone and nidatory oestrogen are required for the induction of implantation. In species not displaying embryonic diapause implantation will take place in the presence of progesterone alone. In the light of these considerations the selection of animal models for drug-screening purposes and possible new approaches to contraception are discussed.

Animals↗
PubMed1978

Cyclic variation in concentrations of protein and hexose in human uterine flushings collected by an improved technique.

Uterine flushings were obtained from fertile women at various stages of the menstrual cycle. A technique was used which excluded contamination with cervical mucus and significantly lowered contamination with blood in comparison with an established technique. Contamination of the uterine flushings with seminal plasma and tubal fluid was also prevented. The concentrations of protein and hexose in the uterine flushings, corrected for contamination with plasma, were significantly lower in the secretory stages than in the proliferative stages of the cycle. It is concluded that proteins and carbohydrates are present within the uterine lumen not only after ovulation but also during the preovulatory period.

Adult↗
PubMed1978

Effect of human uterine flushings collected at various stages of the menstrual cycle on mouse blastocysts in vitro.

Mouse blastocysts were cultured in vitro in a defined medium supplemented with uterine flushings (containing 500 microgram protein/ml) obtained from normal women at various stages of the menstrual cycle. With one exception (uterine flushing collected on the last day of a menstrual period) blastocyst hatching and attachment were not impaired by flushings collected before or after ovulation.

Animals↗
PubMed1978

Protein patterns of human uterine flushings collected at various stages of the menstrual cycle.

Uterine flushings and plasma collected from normal, parous women at various stages of the menstrual cycle were subjected to gel electrophoresis. The protein profiles of the flushings differed in many instances from the plasma pattern by the presence of between one and eleven non-plasma proteins. The distribution of the major non-plasma proteins during the menstrual cycle was not statistically significant but that of a pretransferrin, observed in uterine flushings and in peritoneal fluid, was significant. However, the appearance of this protein band could not be related to a particular phase of the cycle, and hence to a specific hormonal condition.

Ascitic Fluid↗
PubMed1977

Changes in the protein content of mouse uterine flushings during normal pregnancy and delayed implantation, and after ovariectomy and oestradiol administration.

The protein content of the mouse uterine lumen increased significantly (P less than 0-001) on Day 4 of pregnancy, the day of implantation. This increase was associated with the presence of 14 serum and 22 non-serum proteins in the lumen; the major serum proteins were classed as high molecular weight slow alpha-globulins, while the dominant non-serum components consisted of slow and fast alpha-globulins, 6 prealbumins and a large quantity of proteinaceous material migrating near the origin of the gels. During experimental and lactational delayed implantation the protein levels were constantly low, transferrin, haemoglobin and albumin dominating the protein pattern. After administration of oestradiol-17beta, however, a biphasic uterine response was detected, significant increases in luminal protein concentration being observed within 12 h and again at 40-48 h after injection. The first phase of this response involved an influx of serum and non-serum proteins into the uterine lumen, most proteins migrating as high molecular weight slow alpha-globulins. The second phase involved an increase in the intensity of many non-serum components, the major proteins having Ra values of 0-06, 0-10 and 0-32. The qualitative, but not the quantitative, aspects of this response to oestradiol were identical in the absence of blastocysts.

Animals↗