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Biomedical subjects

M G Hull

Publications and source records attributed to M G Hull.

At least 19 recordsLinked to original sources
PubMed1992

Smoking and decreased fertilisation rates in vitro.

To examine possible mechanisms for the association between cigarette smoking and reduced fertility, we have measured the concentration of the nicotine metabolite cotinine in ovarian follicular fluid collected at the time of oocyte recovery during treatment for in-vitro fertilisation. In a group of women in whom follicular fluid cotinine could not be detected (limit of accurate measurement 20 ng/ml) 116 oocytes were collected, of which 84 became fertilised (72%), whereas among women with cotinine concentration greater than 20 ng/ml 20/45 (44%) oocytes did so (p < 0.01). The median fertilisation rates for individuals (range 1-8 eggs each) in the high and low cotinine groups were 57% and 75%, respectively (p < 0.05). These findings suggest that infertile women should be advised to stop or reduce smoking generally, and especially before treatment by in-vitro fertilisation.

Adult↗
PubMed1992

Expectations of assisted conception for infertility.

OBJECTIVE: To provide reliable prognostic information for couples seeking assisted conception. DESIGN: Analysis of four years' practice (1988-91). SETTING: Private university service linked with NHS reproductive medicine services. PATIENTS: 804 couples with various causes of subfertility, median duration five years, median age of women 34 years. INTERVENTIONS: 1280 completed cycles: 950 in vitro fertilisation, 144 gamete intrafallopian transfer, and 186 intrauterine insemination and superovulation. MAIN OUTCOME MEASURES: Pregnancy and birth rates per cycle and cumulative pregnancy and take home baby rates per couple. RESULTS: In women under 40 years and men with normal sperm, whatever the cause of infertility, results with in vitro fertilisation improved steadily reaching a pregnancy rate per cycle of 30% (95% confidence interval 26% to 35%) during 1990-1 and birth rate per cycle of 29% (23% to 35%) in 1990. Pregnancy and birth rates for gamete intrafallopian transfer were 36% (28% to 44%) and 26% (17% to 37%) and for intrauterine insemination 18% (12% to 24%) and 16% (10% to 22%). After six cycles cumulative probability of pregnancy was 82% and cumulative take home baby rate 70%. Considering only in vitro fertilisation and gamete intrafallopian transfer after four cycles the pregnancy rate was 78% (66% to 91%). CONCLUSIONS: Conception is less likely in women over 40 and men with sperm dysfunction. For other couples the prognosis for a live birth is at least as good as for fertile couples if they persist with treatment.

Adult↗
PubMed1992

A prospective controlled study of in-vitro fertilization, gamete intra-fallopian transfer and intrauterine insemination combined with superovulation.

The relative effectiveness of in-vitro fertilization (IVF), gamete intra-Fallopian transfer (GIFT) and intrauterine insemination (IUI) combined with superovulation in the treatment of infertility were compared in 151 couples undergoing a single cycle of treatment. Treatment was selected as appropriate (IVF for tubal disease, GIFT or IUI/superovulation for nontubal infertility) but possible bias due to non-randomization was overcome by all couples having had favourable fertilization in a previous cycle of IVF. Furthermore, in a preliminary study of initial IVF treatment in 265 couples from whom the study patients were drawn, implantation and pregnancy rates in the diagnostic groups were similar. In the definitive study comparing IVF, GIFT and IUI/superovulation, the pregnancy rate observed with GIFT was highest (40%) but this was not significantly higher than with IVF (28%) or IUI/superovulation (20%). However, the implantation rate per egg transferred by GIFT (21%) was significantly higher than the implantation rate per embryo transferred by IVF (11%). Although the pregnancy rates with GIFT were not statistically greater than with IVF, a significant advantage is likely to be observed in larger groups in view of the better implantation rate. The lower pregnancy rates with IUI superovulation are to be expected because of limited ovarian stimulation, they are nevertheless of comparative interest.

Adult↗
PubMed1992

The yield, motility and performance in the hamster egg test of human spermatozoa prepared from cryopreserved semen by four different methods.

Different procedures were investigated for the dilution of human cryopreserved semen and the preparation of an enriched population of motile spermatozoa for assisted reproduction. The dilution of a 0.25 ml straw of cryopreserved human semen by addition of 2.0 ml Ham's F-10 buffer in one step caused a large decrease in the proportion of motile spermatozoa. This was due to osmotic stress because many of the diluted spermatozoa exhibited swollen tails. To a large extent the damage could be avoided by adding the buffer in 0.10-ml aliquots at 30-s intervals. Spermatozoa obtained after such dilution of cryopreserved human semen were subjected to the swim-up procedure, to centrifugation on two-step gradients of Nycodenz or Percoll, or to filtration through glass fibre paper and compared with respect to yield, motility parameters and penetrating ability in the hamster egg test. The swim-up procedure yielded spermatozoa with excellent motility but only 12% of the available motile spermatozoa were recovered. On both Nycodenz and Percoll gradients, greater than 40% of the available motile spermatozoa were recovered and the average velocity of the spermatozoa was not significantly less than for the swim-up technique. When A23187 was used to promote acrosome reactions in the hamster egg test, Percoll-prepared spermatozoa achieved an average of 8.6 decondensed sperm heads/egg compared to 1.9 for Nycodenz and 1.3 for the swim-up procedure. The yield from glass fibre paper filtration was only 12% and the velocity of the spermatozoa and their performance in the hamster egg test was significantly poorer than in all the other methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Infertility treatment: relative effectiveness of conventional and assisted conception methods.

The effectiveness of infertility treatments is still questioned, particularly the assisted conception methods because of their complexity and cost. Furthermore, pregnancies often occur independent of treatment but many treatments have not been properly evaluated. The most basic audit of outcome with or without treatment requires pregnancy and preferably birth rates to be calculated in a cycle-specific and/or time-specific way; cumulative rates are the preferable method of calculation, in order to account for the usual tendency for fecundity to fall progressively. The choice of treatment usually depends on a balance of the chances of conceiving with or without treatment, and with more or less complicated treatments, and on other factors such as duration of infertility and the woman's age. This review aims to address those choices by assessing the actual and comparative effectiveness of treatments insofar as there are well defined and strictly comparable time-specific or cycle-specific published data available. Cumulative rates are described wherever possible and presented graphically for easy reference.

Female↗
PubMed1992

Controlling the swimming speed of human sperm by varying the incubation temperature and its effect on cervical mucus penetration.

The objective of the present experiments was to study the effect of sperm velocity as a single variable on the ability of sperm to penetrate cervical mucus in a modified Kremer test. Sperm incubated at 13, 22 and 37 degrees C exhibited progressive velocities of 25 +/- 1.7, 40 +/- 2.1 and 56 +/- 2.1 microns sec-1 (mean +/- SEM, n = 6) respectively, but the percentage of progressively motile sperm, their lateral head displacement and the viscoelastic properties of cervical mucus remained comparatively unchanged over this temperature range. The number of sperm which penetrated the mucus and the percentage of successful collisions were correlated strongly with the average velocity of the sperm population (r = 0.82 and r = 0.72 respectively). It is concluded that sperm velocity has an important influence on the penetration of cervical mucus because it governs the frequency of collisions with the mucus interface and is determined by the thrust generated by the flagellum which also determines the ability of the sperm to traverse the mucus interface.

Cervix Uteri↗
PubMed1992

Motility characteristics and membrane integrity of cryopreserved human spermatozoa.

The motility characteristics of washed spermatozoa from 50 normal ejaculates were measured by time-lapse photography, before and after cryopreservation. Plasma membrane integrity was assessed by the hypo-osmotic swelling test and with the supravital fluorescent dye bisbenzimide (H33258). There was a marked decline in the percentage of progressively motile spermatozoa after cryopreservation, the extent varying widely among donors. Results were, however, consistent between different ejaculates from the same individual. The ability of spermatozoa to survive cryopreservation could not be predicted from the properties of the semen beforehand. The mean velocity of the spermatozoa was significantly reduced after freezing, but the lateral head displacement was unaltered. There was a significant reduction in the proportion of spermatozoa with intact plasma membranes after cryopreservation and the results of the hypo-osmotic swelling test and H33258 tests correlated closely. There was no correlation between the declines in the percentage of motile spermatozoa, or intact spermatozoa and the sperm velocity. We conclude that membrane rupture is not the sole cause of loss of motile spermatozoa during freezing and that the decrease in the proportion of motile spermatozoa is caused, at least in part, by a separate process from that responsible for the decrease in the average swimming speed of spermatozoa.

Analysis of Variance↗
PubMed1992

The contribution of the toxicity of a glycerol-egg yolk-citrate cryopreservative to the decline in human sperm motility during cryopreservation.

The contribution of the toxicity of glycerol-egg yolk-citrate (GEYC) cryopreservative medium to the loss of function of human spermatozoa during cryopreservation was determined by investigating the effect of mixing semen with the medium on sperm motility. The percentage of progressively motile spermatozoa, velocity (micron s-1) and lateral head displacement (micron) (mean +/- SEM, n = 28) were 55 +/- 4.1, 47 +/- 2.7, 4.4 +/- 0.2 and 32 +/- 3.8, 40 +/- 2.5, 3.6 +/- 0.25 and 15 +/- 2.5, 28 +/- 1.1, 2.8 +/- 0.15 in suspensions of washed spermatozoa prepared from fresh, GEYC-treated and frozen-thawed semen, respectively. The variables changed only slightly after incubation for 3 h. The toxicity of GEYC did not vary significantly between samples which survived the complete freeze-thaw cycle well or very poorly. The toxicity of GEYC is responsible for about 50% of the loss of progressively motile spermatozoa during the complete cryopreservation process, but has little effect on the quality of motility. Susceptibility to GEYC does not explain observed differences in the ability of semen samples to survive freezing.

Citrates↗
PubMed1992

The effect of combined estrogen/progestogen treatment in women with hyperprolactinemic amenorrhea.

Eleven women with hyperprolactinemic amenorrhea were treated with a combined estrogen/progestogen preparation (Loestrin 30) for 3 months as hormone replacement therapy because of estrogen deficiency, with a view to protection against osteoporosis. Serum prolactin levels rose during the 1st month of treatment (p < 0.05) but did not rise significantly further during the 2nd and 3rd months. The levels rose in proportion to pretreatment levels by 28% (median), and fell significantly but not completely during the 1-week treatment-free intervals. After the study period, prolactin values appeared to remain stable in those women who continued longer on treatment, and returned to around pretreatment values in those who stopped. In one woman there was radiological evidence of pituitary tumor growth during treatment. This study shows that estrogen/progestogen treatment in standard contraceptive dosage usually leads to only moderate and non-progressive stimulation of pituitary activity in women with hyperprolactinemic amenorrhea, but occasional excessive growth of a prolactinoma can occur and treatment needs to be monitored. Women with relatively high prolactin levels seem to be at particular risk. Safer variations of estrogen therapy such as lower dosage or combination with a protective low dose of a dopamine agonist should also be considered.

Adolescent↗
PubMed1991

The diagnosis of polycystic ovaries in women with oligo-amenorrhoea: predictive power of endocrine tests.

The ability of several endocrine tests to distinguish between women with and without polycystic ovaries (PCO) has been studied prospectively in a series of 65 patients with functional oligo-amenorrhoea using ultrasonography as a reference test. In terms of overall diagnostic accuracy, the free androgen index (FAI) (94%) and the progestogen challenge (89%) gave similar results (Cl = -5 to 15%) but both were significantly better than all the other tests including measurement of serum LH (69%), total testosterone (71%) and androstenedione (74%) (minimum Cl = 6 to 23%). The FAI together with LH measurement was the most accurate of the combinations (97%) but this was not significantly better than the best of the combinations incorporating the progestogen challenge (92%; Cl = -3% to 13%). Given the limited availability of the assay for SHBG, these results show that assessment of oestrogen state is a useful method for categorizing patients with functional oligo-amenorrhoea.

Amenorrhea↗
PubMed1991

The effect of A23187 concentration and exposure time on the outcome of the hamster egg penetration test.

We investigated the conditions required to enhance the performance of human sperm in the hamster egg penetration test with the free acid form of A23187. The best performance was observed after stimulation with 2 microM A23187 for 1 h when the median penetration rate with sperm from fertile donors was 100% of eggs with 5.8 decondensed sperm heads/egg. Extending the stimulation period with 2 microM A23187 to 2 or 3 h, resulted in a progressive decrease in the penetration rate. In the absence of A23187, the penetration rate was lower (0.7 decondensed sperm heads/egg after 1 h) but increased with stimulation time. A similar picture was observed with sperm from patients taken for an IVF programme. For a pool of cryopreserved semen, the coefficient of variation of the penetration rate after stimulation with 2 microM A23187 for 1 h, expressed as decondensed sperm heads/egg, was 11% within and 20% between assays. There was no correlation between the outcome of the hamster egg penetration test and the percentage motility, velocity or lateral head displacement of the sperm measured after the same stimulation regime. However, in IVF patients the initial velocity and lateral head displacement of the sperm (zero time) were correlated with the best result from the hamster egg penetration test (r = 0.62 and 0.57 respectively). No motility changes characteristic of capacitation were detected. We conclude that stimulation with 2 microM A23187 (free acid) for 1 h prior to the addition of the zona free hamster eggs can produce a high penetration rate with fertile samples and provides a convenient and robust protocol for the assay. However, when carried out in this way the test does not assess the ability of the sperm to capacitate.

Acrosome↗
PubMed1991

Oestrogen and androgen states in oligo-amenorrhoeic women with polycystic ovaries.

Oestrogen and androgen states have been studied in relation to ovarian morphology defined by ultrasonography in 65 women with oligo-amenorrhoea. Of the 48 women with polycystic ovaries (PCO), 44 (92%) had a withdrawal bleed following progestogen challenge (indicating oestrogenization) compared with just three (18%) of the 17 with non-PCO (P less than 0.001). Median serum concentrations of oestradiol and oestrone were statistically significantly higher in the PCO group but the ranges overlapped widely. Of the four women with PCO but oestrogen deficiency, two were hirsute and had evidence of a severe form of the disorder. The other two were not hirsute and appeared to have hypothalamic dysfunction associated with weight loss overriding the disorder due to pre-existing PCO. Compared with the non-PCO group, the PCO subgroup without hirsutism (n = 31) had statistically significantly higher median values of LH, testosterone, androstenedione, and dehydroepiandrosterone sulphate concentrations, and free androgen index. Concentrations of androgen, but not LH, were significantly higher still in the PCO subgroup with hirsutism (n = 17).

Amenorrhea↗