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Biomedical subjects

E Chantler

Publications and source records attributed to E Chantler.

At least 19 recordsLinked to original sources
PubMed2004

Significance of midpiece vesicles and functional integrity of the membranes of human spermatozoa after osmotic stress.

Some human spermatozoa respond to osmotic pressure changes in their surroundings by volume change of vesicles on the plasmalemma in the midpiece domain. We aim to determine how cyclic change in osmotic stress affects motility and permeability of the plasmalemma and whether the response is affected by the presence of a midpiece vesicle. Spermatozoa from normozoospermic men were examined in medium, whose osmolality was adjusted to 276 and 450 mmol kg(-1) with raffinose. Plasmalemma permeability was measured by propidium iodide (PI) uptake and motility assessed by computer-aided semen analysis. Spermatozoa were imaged with fluorescence light and X-ray microscopy. PI staining was significantly increased, and motility decreased only when spermatozoa were cycled from hyper- to hypo-osmotic conditions. A single change in osmotic pressure did not significantly affect PI uptake. As expected, midpiece vesicles swelled and became spherical in hypo-osmotic conditions. However, a significant association existed between osmotically induced plasmalemma damage and absence of a midpiece vesicle. We conclude that the midpiece vesicle is not a consequence of membrane leakage but a normal part of spermatozoon anatomy, conferring resistance to osmotic stress mediated damage. As osmotic stress affects both motility and plasmalemma permeability, the presence of a midpiece vesicle is significant in spermatozoal function and could have implications to understanding specific cases of undetermined male factor infertility.

Cell Membrane↗
PubMed2000

Significance of plasmalemma disruption in bovine and equine spermatozoa.

We have investigated fresh and cryopreserved bovine and equine spermatozoa using light and transmission soft X-ray microscopy. Spermatozoa were examined, in the presence or absence of semen, after using Percoll gradient centrifugation and re-suspending in medium. X-ray microscopy provided high resolution (30 nm) transmission images of whole cells in solution with high contrast, while retaining the simple preparation techniques used in light microscopy. We demonstrated translucent, membrane-bound vesicles in the acrosomal and midpiece regions that were similar in size and we noted their incidence in both fresh and frozen-thawed material from both animals. The vesicles were formed by the separation and expansion of the plasmalemma away from the underlying structure but were not caused by the freeze-thaw process. We suggest that these structures form part of the normal ultrastructure of spermatozoa and are damaged during preparation of the samples for transmission electron microscopy, resulting in a structure previously and incorrectly identified as damaged by the freezing and thawing process.

Acrosome↗
PubMed2000

Effect of cooling on the motility and function of human spermatozoa.

Human spermatozoa were cooled from 37 to 0 degrees C at 10 degrees C min(-1) in 5 degrees C steps with 1 min equilibration at each step, the temperature control was +/- 0.1 degrees C. Spermatozoa were held at 0 degrees C for 5 min and then rewarmed at the same rate. No significant effect of cooling on the straight-line velocity was found using computer-aided semen analysis. The physiological function of spermatozoa was also examined before and after cooling using hypoosmotic swelling, ionophore-provoked acrosome reaction, and binding to fragments of human zonae pellucidae. Spermatozoa were cooled either in seminal plasma or in conventional IVF medium with or without fractionation by centrifugation through a discontinuous Percoll gradient. When spermatozoa were cooled and rewarmed in seminal plasma there was no significant change in either the ionophore-induced acrosome reaction or the binding to zona pellucida fragments. When spermatozoa were fractionated by centrifugation through Percoll an increased response in both was seen. However, following cooling and rewarming, a significant decline in the response of both occurred. We suggest that motility alone is not a reliable predictor of changes in other physiological functions of spermatozoa following cooling. Furthermore, short-term cooling appears to have no significant detrimental effect on normozoospermic samples and cold shock may be avoided in the clinical context by controlled cooling and warming.

Acrosome↗
PubMed2000

Properties of sperm separated using Percoll and IxaPrep density gradients. A comparison made using CASA, longevity, morphology and the acrosome reaction.

Since the withdrawal of Percoll from use in human assisted reproduction techniques in 1996, alternative density gradients have been sought. IxaPrep is one candidate that has low toxicity and can separate spermatozoa. Fractions of spermatozoa from normozoospermic men, separated by Percoll and IxaPrep gradient centrifugation, were assessed for sperm recovery, motility, morphology and the ability to undergo the acrosome reaction. The Percoll fractions had a significantly higher sperm recovery, motile count, rapid motile count, VAP, VSL, and VCL than those obtained using IxaPrep, both immediately after separation and up to 24 h later. In contrast, ALH, level of abnormal sperm morphology and the ability to acrosome react were not statistically different in sperm fractions separated using either gradient forming material.

Acrosome Reaction↗
PubMed1999

Fecundity in the modern city: a comparison of couples attending antenatal clinics in Manchester (UK) and Melbourne (Australia).

To determine the characteristics of couples with resolved subfecundity and to compare these findings in two geographically distant centres, a self-reporting questionnaire was completed by a sample of women attending six antenatal clinics in Greater Manchester, UK and five antenatal clinics in Melbourne, Australia. A total of 2158 pregnant women, 1106 from Manchester and 1052 from Melbourne participated in the study. The prevalence of subfecundity (proportion of women who failed to conceive current pregnancy within 12 months of unprotected intercourse) and demographic and medical factors potentially related to subfecundity were measured. The samples from the two cities had similar medical characteristics, but several socioeconomic and cultural differences were detected. Characteristics which independently correlated with decreased fecundity were increasing parental age, previous pregnancy, previous miscarriage, maternal smoking before conception and low socioeconomic status. Increased body mass index was also a significant, independent predictor of decreased fecundity, but in the Melbourne sample only. Subfecundity was found to be influenced by a combination of parental and socioeconomic factors as well as previous pregnancy. The factors identified were similar in two modern industrial societies in very different geographical locations, only their relative importance differing between Australia and the UK.

Journal Article↗
PubMed1998

Diffusion of nonoxynol-9 into human semen in vitro.

The diffusion of [125I]-nonoxynol-9 into human semen was investigated in vitro before and after liquefaction. No significant difference was found in the distribution of [125I]-nonoxynol-9 within columns of preliquefied semen, liquefied semen, seminal plasma, or water after < or = 120 minutes of diffusion; however, significantly more nonoxynol-9 entered preliquefied semen. The concentration of nonoxynol-9 that entered semen in vitro was greater than its ED100 and the bioavailability was confirmed by demonstration of the retention of spermicidal action. These results indicate that the gel state of preliquefied semen does not inhibit the entry or action of nonoxynol-9 and, consequently, sperm would be exposed to it immediately when it is used in vivo as a vaginal spermicide.

Adult↗
PubMed1998

Human ovarian granulosa cells and follicular fluid indices: the relationship to oocyte maturity and fertilization in vitro.

The study investigates the correlation between oocyte maturity and fertilization and a variety of hormonal parameters in follicular fluid and ovarian granulosa cells. A methodology for purification of granulosa cells from contaminating blood cells is also established. A total of 63 follicular aspirates were collected at oocyte retrieval from 30 women superovulated using the long luteinizing hormone-releasing hormone (LHRH analogue)/human menopausal gonadotrophin regimen. Oestradiol, progesterone, testosterone and human chorionic gonadotrophin (HCG) were quantified in follicular fluid and granulosa cells were immunostained for human chorionic gonadotrophin. Immunopurification of granulosa cells from contaminating blood cells was performed. HCG in follicular fluid was significantly high in follicles yielding immature (grade 3) oocytes (P=0.002); there was no correlation with fertilization. Aspirates from follicles containing mature (grade 1) oocytes and oocytes that subsequently fertilized had significantly more granulosa cells immunobound to HCG (P < 0.001, P=0.02). Moreover, the immunomagnetic purification technique provided >98% pure population of granulosa cells. The data demonstrate that HCG in follicular fluid and on granulosa cells may help to predict oocyte maturity and fertilization. Furthermore, immunomagnetic beads provide a reliable procedure for the purification of ovarian granulosa cells.

Adult↗
PubMed1998

The effect of nonoxynol-9 and chlorhexidine on HIV and sperm in vitro.

The effect of chlorhexidine and nonoxynol-9, either singly or in combination, on the replication and infectivity of HIV and the survival of both lymphocytes (MT2 cells) and human spermatozoa, was studied in vitro. Exposure of MT2 cells to 200 microg/ml nonoxynol-9 or 1 mg/ml chlorhexidine for one minute destroyed their viability. A combination of 60 microg/ml of nonoxynol-9 and chlorhexidine, however, killed MT2 cells under the same conditions. Nonoxynol-9 and chlorhexidine were both spermicidal, 268 microg/ml nonoxynol-9, or 2.063 mg/ml chlorhexidine caused complete immobilization of sperm after one minute. The same effect was achieved by a combination of 200 microg/ml nonoxynol-9 and 1.0 mg/ml chlorhexidine. The effect of chlorhexidine and nonoxynol-9 on the replication of HIV was estimated by the output of p24 (the HIV core protein) and the concentration of virus was determined by titration with MT2 cells. Separately, 300 microg/ml nonoxynol-9 alone completely inactivated HIV, while 1 mg/ml chlorhexidine was 80%-100% effective. Certain combinations of nonoxynol-9 and chlorhexidine were antagonistic in their inactivation of HIV, up to 400 microg/ml chlorhexidine partly neutralized the action of 200-500 microg/ml nonoxynol-9.

Anti-HIV Agents↗
PubMed1995

Comparative analysis of motility characteristics of Percoll-selected spermatozoa populations from fresh and cryopreserved semen.

The proportion and quality of motility of spermatozoa in normozoospermic ejaculates were assessed using computer-assisted semen analysis. The ejaculate was split and the motility re-assessed following separation on a Percoll gradient with or without cryomedium and cryopreservation. Cryopreservation caused a significant decrease in the proportion of motile spermatozoa and in their velocity and amplitude of lateral head displacement. The initial decrease in the proportion of motile spermatozoa was found to be in part an effect of the cryomedium. The use of Percoll gradient separation did not initially change these effects but after 4 h incubation differences in velocity and amplitude of lateral head displacement between samples were no longer evident. Percoll-selected, cryopreserved spermatozoa had both a stable proportion of motile spermatozoa and a stable velocity for at least 48 h, whereas in fresh spermatozoa populations, similarly separated using Percoll, the proportion of motile spermatozoa had decreased by 24 h and the velocity was lower at 48 h. Percoll preparation is an effective method for the selection of motile spermatozoa from cryopreserved semen which, after a short incubation, have similar motility characteristics to fresh spermatozoa.

Cell Separation↗
PubMed1994

An analysis of the corrosion process of the Nova-T IUD.

OBJECTIVE: To measure the copper from Nova-T IUDs that have been used for up to 9 years. To examine the composition and extent of surface deposits on these used IUDs. DESIGN: Nova-T IUDs were randomly collected at normal replacement or removal. The copper, silver and calcium content was quantified by X-ray fluorescence; surface topography and analysis was by scanning electron microscopy and X-ray dispersive analysis. RESULTS: Copper loss slowly increased at an exponential rate over the study period but the copper was stabilized by the silver core and did not show increased fragmentation with extended use. No corrosion of the silver core was detected. Calcium- and sulfur-containing surface deposits built up on the copper but did not modify the rate of copper release. CONCLUSIONS: The mean rate of copper loss was 0.25 mumol/day during the first 40 months of use, which is not significantly different from that of similar IUDs without a silver core. The silver core of the copper coil on the Nova-T IUD prevented its fragmentation. Surface deposits containing calcium and sulfur that built up on the IUD did not affect the rate of copper loss.

Calcium↗
PubMed1994

Ovulation induction and endometrial steroid receptors.

The endometrial morphology, endometrial steroid receptors and serum steroid hormone concentrations have been studied in 22 infertile women participating in an in-vitro fertilization, gamete intra-Fallopian transfer programme, including nine cases following treatment with gonadotrophin-releasing hormone analogue/human menopausal gonadotrophin/human chorionic gonadotrophin. All patients had normal ovulatory function before treatment and satisfactory response to ovulation induction. Endometrial biopsies were taken in spontaneous and treatment cycles on the fourth day after ovulation had been detected by ultrasound scanning, when endometrial receptors were measured using immunohistochemistry. Histological examination of biopsies in spontaneous cycles showed the majority (20/22) to be 'in-phase', while in two cases luteal phase defect was diagnosed. After ovulation induction, all the biopsies were still morphologically 'in-phase', although a significant reduction had occurred in the nuclear receptor level in both the glands and stroma for both progesterone receptors (gland P = 0.030, stroma P = 0.012 using microscopic analysis; gland P = 0.020, stroma P < 0.001 using a cell analysis system) and oestrogen receptors (gland P = 0.017, stroma P = 0.002 using direct microscopic analysis). This suggests that a reduction in steroid receptors in the endometrium occurs after ovulation induction in the presence of supraphysiological amounts of steroids, which is not associated with detectable morphological changes.

Adult↗
PubMed1993

Contraception and the prevention of sexually transmitted diseases.

Sexually transmitted diseases (STDs) are a major cause of ill health in women and their sexual partners and children. Contraceptive methods alter in various ways the risk of acquiring STD but assessment of the odds ratio is difficult due to the many confounding factors. Spermicides have been reported to kill a wide range of bacteria and viruses including HIV in vitro and to protect in vivo from infection by gonorrhoea, chlamydia and pelvic inflammatory disease (organisms unspecified). Spermicides will not cure pre-existing infections. Condoms and diaphragms will give some protection from bacterial and viral infections in all parts of the genital tract. Hormonal contraception and tubal ligation give protection to the upper genital tract but not the cervix. Carcinoma of the cervix follows the same pattern as STDs. The risk of pelvic infection in intrauterine device users is discussed in the chapter by Bromham (pp 100-123, this issue).

Adult↗
PubMed1992

Compatibility between the spermicide nonoxynol 9 and mid-cycle human cervical mucus.

The rate of diffusion of [125I]-nonoxynol 9 into mid-cycle human cervical mucus was measured and found to be negligible compared with D-glucose (used as an uncharged small molecule for comparison with nonoxynol 9). These data were confirmed by observation of the lack of inhibition of the movement of spermatozoa in mucus that had been in surface contact, for 3 hours, with a concentration 30 times greater than the ED100 of nonoxynol 9. These results show that the entry of nonoxynol 9 into mucus could be minimal under conditions that would exist in vivo and highlights a limitation of this compound as a vaginal contraceptive.

Cervix Mucus↗
PubMed1992

Quantification of the in vitro activity of some compounds with spermicidal activity.

The in vitro spermicidal activity of the commonly used surfactant spermicides and the antiseptic chlorhexidine, were quantified in a statistically reproducible manner, using donor semen and image capture analysis. The spermicidal activity was expressed as the ED50 under defined assay conditions. Using these parameters, the order of spermicidal activity was: Menfegol > nonoxynol-9 approximately benzalkonium chloride > sodium docusate > chlorhexidine. These differences were statistically significant.

Benzalkonium Compounds↗
PubMed1991

Evidence for shared epitopes within the 'naked' protein domains of human mucus glycoproteins. A study performed by using polyclonal antibodies and electron microscopy.

Polyclonal antibodies were raised in rabbits towards reduced subunits of human cervical mucus glycoproteins. The reduced subunits almost completely inhibited the antiserum, whereas the intact mucins and the heavily glycosylated fragments obtained after digestion of reduced subunits with trypsin (T-domains) caused only partial inhibition. Periodate oxidation of intact mucins, reduced subunits and T-domains caused no effect on the antibody response, and fragments obtained by more extensive proteolysis of the reduced subunits (P-domains) showed no inhibitory activity. By using electron microscopy, antibodies from T-domain-adsorbed antisera were revealed as bound to cervical mucin reduced subunits, either directly or with colloidal gold-Protein A. Binding sites (100-150 nm apart) were observed at the ends and at internal positions of the reduced subunits. We conclude that the antibodies do not recognize carbohydrate structures but are directed to two kinds of protein epitopes, one shared by whole mucins, reduced subunits and T-domains, and the other specific to the reduced subunit fragment. The latter epitopes are 'cryptic' and are probably shielded within folded protein domains stabilized by disulphide bonds. Human bronchial, cervical, gastric and salivary mucus glycoproteins share some of these cryptic epitopes.

Antibodies↗
PubMed1989

Changes in cervical mucus that prevent penetration by spermatozoa.

Two situations that result in the conversion of human mid-cycle cervical mucus from a sperm-receptive to a sperm-hostile form are described here: firstly, the addition of mucospissic agents, and secondly, the presence of antisperm antibodies. Two mucospissic biguanides were studied, chlorhexidine and Vantocil; both were totally spermicidal in the range 1-10 mg ml-1. Treatment of mucus with 1.5 microM to 1.65 mM Vantocil caused a dose-dependent increase in the dynamic storage modulus. The compatibility of the two biguanides with mucus was examined by measuring the rate of entry of diffusion of the [14C]biguanides into mucus. Chlorhexidine entered the mucus up to 0.53 mM, i.e. the highest concentration used, whilst Vantocil only entered at concentrations below 0.53 mM. This limited entry may be caused by the precipitation of mucus at the interface, producing a barrier of reduced permeability. The behaviour of purified mucin on ultracentrifugation was also altered after treatment with chlorhexidine. The s20 (at 2 mg ml-1 purified mucin) increased from 11.2 S to 19.3 S upon addition of 200 microM chlorhexidine. Further indication of structural alteration of biguanide-treated mucin was given by its loss of solubility in 0.22 M-sodium thiocyanate. The application of these biguanides to vaginal contraception is suggested. When antisperm antibodies are present in either the semen or cervical mucus, we suggest that an interaction can occur between galactose residues on the spermatozoa and galactose recognition sites on the antisperm antibody; in addition, binding can also occur between the Fc region of the antibody and cervical mucus. This process could therefore contribute to the binding of spermatozoa to the antibody and the immobilisation of this complex by the cervical mucus that is seen in immunological infertility. It was shown, by Immunobead binding, that immediate exposure of spermatozoa to D-galactose in the presence of chymotrypsin resulted in a considerable decrease or total loss of bound antisperm antibodies in males who had previously had a high titre of antibody. This reduction in the antibody level on the spermatozoa was accompanied by the appearance of the antibody level on the spermatozoa was accompanied by the appearance of the ability of the spermatozoa to penetrate cervical mucus in those couples examined. This pretreatment regimen for the ejaculate is suggested as a form of therapy for infertility related to the presence of antisperm antibodies.

Antibodies↗
PubMed1986

Comparison of the action of nonoxynol-9 and chlorhexidine on sperm.

The effect on sperm motility of nonoxynol-9 chlorhexidine diacetate was compared in semen and cervical mucus. Both compounds had similar spermicidal potency in semen, abolishing sperm motility within 3 minutes at 0.5 mg/ml. When these compounds were allowed to diffuse into mucus, the subsequent survival of sperm in the mucus was different. Restricted penetration and loss of motility occurred rapidly after treatment with 0.1 mg/ml chlorhexidine, whereas sperm survived normally in mucus after prolonged contact with 200 mg/ml chlorhexidine. When the compounds were mixed directly with the mucus before sperm penetration was attempted, chlorhexidine still immobilized sperm, but concentrations of nonoxynol-9 that would be spermicidal in semen had no effect in mucus.

Animals↗