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Biomedical subjects

M Macnamee

Publications and source records attributed to M Macnamee.

12 recordsLinked to original sources
PubMed1997

Field trial of a diluent for the transportation of human semen at ambient temperatures.

OBJECTIVE: To examine the ability of a citrate-yolk buffer extender to preserve human semen samples at ambient temperatures over a 25- to 30-hour period. DESIGN: Human semen samples were diluted 1:1 with citrate-yolk buffer or homologous seminal plasma and transported at ambient temperature between two distant locations (London to Edinburgh, United Kingdom). Various criteria of semen quality then were assessed before and after 25 to 30 hours storage and transportation in these diluents. SETTING: An institutional research laboratory and a private fertility clinic. PATIENT(S): Samples were provided by 21 donors of unknown fertility and 7 asthenozoospermic patients. INTERVENTION(S): The diluent used to preserve human semen comprised an egg yolk buffer supplemented with fructose and citrate. MAIN OUTCOME MEASURE(S): Aspects of semen quality assessed included movement, hyaluronate penetration, viability, acrosome reaction, and reactive oxygen species generation. RESULT(S): The deterioration of semen quality at ambient temperatures could be prevented by the presence of citrate-yolk buffer, permitting the accurate analysis of oxidative stress and human sperm function, 25 to 30 hours postejaculation. CONCLUSION(S): Citrate-yolk buffer offers considerable promise as a medium for the ambient temperature storage and transportation of human semen.

Acrosome↗
PubMed1996

Studies on the development of diluents for the transportation and storage of human semen at ambient temperature.

Storage of human semen samples at ambient temperature for 24 h resulted in a significant loss of sperm motility from a mean 45.1 +/- 1.8% to 13.8 +/- 1.1% (n = 148). This motility loss was associated with a significant increase in the osmolality of the seminal plasma and the induction of peroxidative damage to the spermatozoa. Both of these detrimental changes could be prevented by diluting the original semen sample 1:1 with a citrate-egg yolk, buffer (CYB). In the presence of this extender all aspects of semen quality were efficiently preserved for 24 h, including sperm movement, penetration of a cervical mucus substitute, the acrosome reaction and sperm-oocyte fusion. CYB extension also permitted the use of chemiluminescent tests of leukocyte contamination to be performed on semen samples stored for 24 h at ambient temperatures. As a preservation medium, CYB was found to be superior to alternative formulations lacking citrate and storage at ambient temperatures was preferable to 4 degrees C. Significant improvements in motility retention were also observed when CYB was supplemented with pentoxifylline, although this treatment significantly stimulated peroxidative damage in the spermatozoa. However, if the pentoxifylline was combined with antioxidants then this collateral peroxidative damage could be reduced and the performance of CYB significantly enhanced. These results have implications for the design of diluents permitting the long-term storage and transportation of human semen samples at ambient temperatures.

Animals↗
PubMed1995

An evaluation of the effect of pentoxifylline on sperm function and treatment outcome of male-factor infertility: a preliminary study.

OBJECTIVE: Our objective was to study the effect of pentoxifylline (PF) on fertilization rates in couples with previous failure of fertilization and male-factor infertility and to determine the predictive value of conventional semen analysis parameters in selecting the couples who would benefit from the elective use of PF in IVF. DESIGN: This prospective controlled study was conducted in an assisted conception METHODS: Sixty-nine couples with previous failed IVF cycle, who had a low fertilization rate and/or male-factor infertility, were recruited to the study. Multiple follicular development was induced using the same protocol of human menopausal gonadotropin and gonadotropin releasing hormone analogue in both cycles. The oocytes were inseminated with spermatozoa treated with PF. The fertilization rates in the PF cycle were compared to the reference cycle based on semen analysis parameters and previous fertilization rates. RESULTS: In couples with male infertility, the fertilization rate improved significantly, from 17 to 50% in PF cycles (P < 0.001). A significant improvement in fertilization rate was also demonstrated in couples with previous poor fertilization, < 30% (P < 0.01), particularly in those with a very low fertilization rate, < 20% (P < 0.001). Although there was an overall improvement in fertilization rates in couples with male-factor infertility, there was no cutoff value in sperm motility that would make a significant difference in the impact of PF on fertilization rates. CONCLUSION: Couples with poor fertilization rates in vitro benefit with a significant improvement in fertilization by the elective use of PF. The improvement is most significant in couples with previous complete failure of fertilization and poor fertilization rates, < 30%.

Adult↗
PubMed1995

Successful use of pentoxifylline in male-factor infertility and previous failure of in vitro fertilization: a prospective randomized study.

OBJECTIVE: Our objective was to determine whether the use of pentoxifylline (PF) would improve the in vitro fertilization (IVF) rate and outcome in couples with male factor infertility and previous failure of fertilization in vitro. DESIGN: This prospective randomized controlled study was conducted in an assisted conception unit. MATERIALS AND METHODS: Forty-nine couples with previous failed fertilization in vitro attributable to male factor or male-factor infertility without previous IVF were recruited for the study. Controlled ovarian hyperstimulation was performed using a combination of gonadotropin releasing hormone agonist and human menopausal gonadotropin. Oocytes of the same grade and maturity were inseminated with spermatozoa treated with PF or control spermatozoa. A maximum of three embryos was replaced after 48 hr and all other embryos were cryopreserved. Pregnancy outcome was followed up and evidence of fetal or neonatal anomalies reported. RESULTS: A significantly higher fertilization rate occurred in the group where oocytes were inseminated with spermatozoa treated with PF compared with controls (56.3 versus 30.7%; P < 0.05). Fertilization occurred in 45 of the 49 cycles (92%). In seven cycles, only the oocytes that were inseminated with spermatozoa treated with PF fertilized, in contrast to only one cycle where the oocytes inseminated with control sperm fertilized (P < 0.05). Fifty-seven PF and 31 control embryos were replaced and 11 clinical pregnancies occurred. Three of the pregnancies occurred in the seven cycles in which only PF embryos were replaced, one in the single cycle where control embryos were replaced and seven from the 37 cycles in which both PF and control embryos were replaced. There was no evidence of congenital malformations in any of the offsprings resulting from this study. CONCLUSION: This study suggests that PF improves the fertilization rate and outcome in couples with male factor infertility and poor fertilization rates. This study does not suggest any increase in teratogenicity or evidence of congenital malformations in pregnancies following IVF cycles where PF was used.

Adult↗
PubMed1995

Heterotopic pregnancies after in-vitro fertilization and embryo transfer.

A total of 20 cases of heterotopic pregnancy were encountered among 2650 clinical pregnancies (0.75%) resulting from in-vitro fertilization/embryo transfer at Bourn Hall Clinic (Cambridge, UK) during the period July 1984-July 1993. The aetiology of heterotopic pregnancy in the series is multifactorial, with tubal damage as the main factor. Transvaginal ultrasonography showed a high sensitivity for making correct diagnoses of heterotopic pregnancies compared with transabdominal ultrasonography (93.3 versus 50.0%). The mean plasma human chorionic gonadotrophin (HCG) concentration on day 13 after embryo transfer was similar to those of uncomplicated intrauterine pregnancies and hence was of no diagnostic value. The serial plasma HCG concentrations of patients who delivered were significantly higher than for those who aborted their intrauterine pregnancies (P < 0.01), although the sample of data available was too small to make firm inferences. It does appear that serial HCG concentrations may have a predictive value of fair accuracy regarding the outcome of the intrauterine pregnancy in heterotopic pregnancies. The clinical presentations of the 20 cases at first examination were quite variable, with 45% (9/20) of patients asymptomatic. Tubal pregnancy in one patient resolved spontaneously, two cases were treated by an injection of potassium chloride into the gestational sac and the remaining 17 cases were treated by salpingectomy. In 10 patients the intrauterine pregnancy resulted in live birth and the remaining 10 patients aborted spontaneously.

Adult↗
PubMed1995

The prediction of ectopic pregnancy after in-vitro fertilization and embryo transfer.

Data from 135 patients who suffered ectopic pregnancies and from 135 patients who progressed to singleton deliveries after in-vitro fertilization and embryo transfer have been analysed retrospectively. The ectopic pregnancies represent all such cases observed at Bourn Hall Clinic between 1983 and 1993. The delivered group was randomly selected from the same time period. The ectopic pregnancies included 20 heterotopic, eight ovarian and six bilateral tubal pregnancies; the remainder were singleton tubal pregnancies. The aim of this study was to identify the variables which differed systematically for the two groups of patients and to explore whether such variables could be used to predict ectopic pregnancy at an early stage. The mean plasma concentration of human chorionic gonadotrophin and progesterone for the ectopic pregnancy group was significantly lower than that for the singleton delivery group (P < 0.001). However, there was such a degree of overlap that it was impossible to devise a cut-off concentration for either hormone which would offer a clinically useful predictor of ectopic pregnancy. Nevertheless, using the discriminant function analysis of these data, together with the history of pelvic inflammatory disease, we could predict up to 90% of cases of ectopic pregnancy by day 23 after embryo transfer, long before ultrasound imaging would be useful.

Chorionic Gonadotropin↗
PubMed1995

Stage-specific expression of cytokine and receptor messenger ribonucleic acids in human preimplantation embryos.

There is considerable evidence to suggest that polypeptide growth factors from either the oviduct or the endometrium can control preimplantation development of the mammalian embryo. These act directly through receptors expressed on the embryo. In addition, embryos also produce growth factors. The reverse transcriptase-polymerase chain reaction (RT-PCR) was used to determine the pattern of expression of mRNAs encoding several growth factor ligand and receptor genes throughout preimplantation development of cryopreserved human embryos. Transcripts encoding the receptor for c-fms, the receptor for colony-stimulating factor-1 (CSF-1), and c-kit (the receptor for stem cell factor [SCF]) were expressed throughout preimplantation development. Other growth factor ligand and receptor transcripts were expressed in a stage-specific manner: these included receptors for interleukin (IL)-6 (IL-6R), leukemia inhibitory factor (LIFR), tumor necrosis factor alpha (TNF alpha) (TNFRp80 and TNFRp60), and gp130. The transcripts for gp130 and the ligand SCF showed stage-specific splice variants. Blastocysts expressed a novel cDNA encoding gp130, which predicts a truncated form lacking the intracellular signaling domain. No expression of mRNAs encoding LIF, CSF-1, or the cloned receptor for platelet-activating factor was seen in any embryonic stage studied. We have shown that RT-PCR provides a sensitive and powerful method for identifying transcripts encoding growth factors and their receptors in single human embryos. The method is economical, allowing the expression pattern of many genes to be determined from a single embryo. These data are important in defining which cytokines may be involved in regulating human preimplantation development and when they may act.

Amino Acid Sequence↗
PubMed1993

Comparative trial between an ultra-short and long protocol of luteinizing hormone-releasing hormone agonist for ovarian stimulation in in-vitro fertilization.

A total of 312 patients with tubal infertility participated in a prospective randomized study comparing two regimens of ovarian stimulation with a luteinizing hormone-releasing hormone agonist (buserelin) and human menopausal gonadotrophin (HMG). Half of the patients were given an ultra-short treatment protocol when the agonist was administered on days 2, 3 and 4 of the stimulated cycles; the other half were given a long protocol when the agonist was administered from the mid-luteal phase of the cycle preceding the treatment cycle. The mean number of HMG ampoules used per patient was significantly higher in the long protocol. No significant differences were found between the two groups in the incidence of cancelled cycles, failed oocyte recovery, mean number of oocytes recovered per patient, complete failure of fertilization and the fertilization and embryo cleavage rate. More patients undergoing the long protocol had supernumerary embryos cryopreserved and successful deliveries.

Adult↗
PubMed1991

High fecundity of amenorrhoeic women in embryo-transfer programmes.

There is uncertainty over whether the steady decline in human fertility with increasing maternal age is due to quality of the oocyte or of the endometrium. To clarify the issue age-related implantation and pregnancy rates in two embryo-transfer programmes were examined in relation to embryo quality and type of menstrual cycle. In both the UK and the US programmes rates were higher in previously amenorrhoeic (acyclic) women than in eugonadal women, irrespective of age and number of embryos replaced. Oocyte quality, as determined by age of oocyte donor, in-vitro growth of embryo, and proportion of defective embryos in culture, did not contribute to the difference, nor did type of cycle during therapy. If a uterus that has not been subjected to regular menstrual cycles is a favourable factor, a period of induced amenorrhoea might be beneficial for infertile women.

Amenorrhea↗