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Biomedical subjects

K S Lindsay

Publications and source records attributed to K S Lindsay.

5 recordsLinked to original sources
PubMed1989

Semen cryopreservation in men undergoing cancer chemotherapy--a UK survey.

A questionnaire was sent to all centres in the UK involved in cryopreservation of semen from men with malignant disease. Details were requested of samples stored from 1977 to 1987 and of successful use of this sperm in subsequently achieving pregnancy. Twenty-two centres are involved and have stored specimens from 2,219 men. There has been a three-fold increase in referrals in the past five years. Three regions in England have no service. Twenty-seven pregnancies (21 live births) have been achieved in 22 couples. Laboratories are poorly funded, making adequate record keeping and audit of the service difficult.

Cryopreservation↗
PubMed1989

Extended exposure to follicular fluid is required for significant stimulation of the acrosome reaction in human spermatozoa.

The effect of human follicular fluid (FF) on the incidence of spontaneous acrosome reactions (AR) in human spermatozoa was examined over a 24-25 h period using electron microscopy. Suspensions of motile spermatozoa were prepared by a swim-up method in Earle's medium, known to support in-vitro fertilization. After adjusting the concentration to 10 x 10(6) cells/ml, suspensions were diluted 1:1 with medium (control) or FF, the latter giving a final concentration of 50% FF. In addition, at 5 h and 24 h an aliquant of the control suspension was removed, diluted 1:1 with FF and incubated for 1 h; the three suspensions were examined at 6 h and 25 h. Continuous exposure to 50% FF stimulated the AR, the effect being significant (P less than 0.001) at 25 h. However, the 1-h short exposure of spermatozoa to FF did not produce an increase in AR, even after 24 h preincubation. In a separate series of experiments, the effect of continuous incubation for 24 h in increasing concentrations of FF was investigated. A significant linear dose-dependent effect on the AR was observed with all concentrations assessed (P less than 0.01 for 12.5% FF and P less than 0.001 for 25, 50, 75 and 100% FF, compared with FF-free control). Therefore, human FF can stimulate the AR, but only after a continuous exposure to FF. A short exposure to FF, even after 24 h preincubation, does not trigger an increased AR response.

Acrosome↗
PubMed1989

Human oocyte-cumulus complexes stimulate the human acrosome reaction.

Oocyte-cumulus complexes were obtained, after induced ovulation, from infertile patients participating in an in-vitro fertilization programme. About 6 h after retrieval and depending on the expansion of the cumulus, 100,000 motile spermatozoa, prepared by a migration-centrifugation method, were added. After 14-18 h incubation at 37 degrees C, oocytes were examined for signs of fertilization (pronuclei and polar body formation) and then removed; spermatozoa remaining in the incubation medium were fixed for transmission electron microscopy. To provide an adequate number of cells for observation, spermatozoa from a minimum of 3-5 oocytes from the same patient were pooled. When sufficient spermatozoa were available after insemination, the remainder of the suspension was incubated at 37 degrees C and fixed along with the corresponding oocyte-incubated sample. In all, 32 sperm samples were assessed and fertilized oocytes were obtained with 29 of these. In the 24 samples in which greater than 100 spermatozoa (mean of 192) could be assessed, 32% of spermatozoa had initiated or completed the acrosome reaction. In the 15 of these 24 samples for which oocyte-free controls were available, 31% of cells were reacting or reacted, compared with 15% of cells (P less than 0.001) in the controls. In the remaining 8 samples, incubated with oocyte-cumulus complexes, less than 100 but greater than or equal to 20 spermatozoa (mean of 42) were assessed and again 32% of spermatozoa were reacted.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1988

Programmed gamete intrafallopian transfer (GIFT).

Thirty-three patients with unexplained infertility underwent a total of 42 programmed superovulation cycles in a gamete intrafallopian transfer (GIFT) programme. The date of oocyte retrieval was decided in advance and the cycle preceding oocyte collection was modified with norethisterone from mid-cycle until 14 days before the scheduled laparoscopy. This was followed by a fixed schedule superovulation regimen. Serum oestradiol, progesterone and luteinizing hormone were monitored and the data analysed retrospectively. A single ultrasound scan was performed on the day of laparoscopy to exclude ovulation. Thirty-eight GIFT procedures were performed, resulting in 11 (29%) clinical pregnancies of which four twin and four singleton pregnancies are continuing. There was a significant correlation between the oestradiol response pattern and the maturity of oocytes retrieved, the fertilization rate of supernumerary oocytes and the pregnancy rate. Programmed cycles may be conveniently combined with GIFT, and basic endocrinological monitoring can be used to identify cycles with a poor prognosis before laparoscopy.

Adult↗