Search PubMed⌕ Search

Biomedical subjects

S Thornton

Publications and source records attributed to S Thornton.

At least 55 records · Page 3Linked to original sources
PubMed1998

Low plasma levels of hCG after 10,000-IU hCG injection do not reduce the number or maturation of oocytes recovered in patients undergoing assisted reproduction.

PURPOSE: Our purpose was to determine whether there is a correlation between human chorionic gonadotropin (hCG) blood levels and oocyte maturation. METHODS: Three samples of blood were obtained at different times from hCG administration as follows: 12 hr, 36 hr, during oocyte recovery, and at 84 hr, when the patient comes for embryo transfer. RESULTS: A total of 5036 oocytes was retrieved from 404 patients prospectively recruited between April 1996 and March 1997. The percentage of metaphase-II oocytes at different blood levels ranged from 84 to 88%. The general trend does not show any significant increase in percentage of metaphase-II oocytes in association with an increasing serum hCG concentration. CONCLUSIONS: The results of this study suggest that at 12, 36, and 84 hr after hCG administration, levels as low as 50, 45, and 9 IU/L of hCG, respectively, are equally potent as higher levels at initiating maximal oocyte maturity.

Adult↗
PubMed1998

Frozen-thawed epididymal sperm is effective for intracytoplasmic sperm injection: implications for the urologist.

OBJECTIVE: To evaluate the pregnancy potential of frozen-thawed surgically retrieved epididymal sperm when used with intracytoplasmic sperm injection (ICSI). PATIENTS AND METHODS: From August 1994 to January 1997, 20 thawed samples of sperm from 19 patients, surgically retrieved and frozen after percutaneous or open epididymal aspiration, were used for ICSI. The results were compared with those obtained using fresh sperm obtained at the same procedure. RESULTS: Of the specimens of surgically retrieved sperm which had been frozen, stored and thawed, 15 had sufficient motile sperm for use with ICSI. The fertilization, cleavage and pregnancy rates in those cycles were similar to the same couples' previous cycle using fresh sperm from the same collection and to the overall results in the NURTURE ICSI programme obtained with fresh epididymal sperm. CONCLUSION: Scrotal exploration for diagnostic testicular biopsy and/or reconstructive surgery without having access to sperm-freezing and storage facilities could represent a lost opportunity for the patient.

Adult↗
PubMed1998

The predictive value of the zona-free hamster egg penetration test in relation to in-vitro fertilization at various insemination concentrations.

The aim of the study was to evaluate the predictive value of the zona-free hamster egg penetration test (ZHEPT) for success in in-vitro fertilization (IVF) at various insemination concentrations ranging between 0.1 and >0.6 x 10(6)/ml. The ZHEPT was assessed using sperm samples from 87 couples undergoing IVF treatment. A similar test was simultaneously performed on the same semen sample following ionophore induction of the acrosome reaction (ZHEPTii test). Both the tests were poorly correlated with the fertilization rate of IVF at all the insemination concentrations except at >0.6 x 10(6)/ml, when there was good correlation between the ZHEPTii test and the fertilization rate. Following exclusion of two cases with an oocyte problem, further statistical analysis revealed that both the ZHEPT and ZHEPTii tests were poorly correlated with fertilization rate in IVF in this treatment group. This study suggests that the ZHEPT (with and without ionophore induction of the acrosome reaction) has a poor predictive value for the success of fertilization in IVF treatment at any insemination concentration.

Adult↗
PubMed1998

Correlation between intracellular cAMP content, kinematic parameters and hyperactivation of human spermatozoa after incubation with pentoxifylline.

Various compounds have been used in the attempt to improve sperm motility, including pentoxifylline (PF), a methylxanthine derivative. It has been postulated that PF, being a phosphodiesterase inhibitor, increases sperm kinematic parameters and the number of spermatozoa exhibiting hyperactivated motility by raising the intracellular content of cAMP, a molecule involved in the generation of sperm energy. However, it has not been clarified whether the biological effects of PF on sperm motility correlate with its ability to increase intracellular cAMP levels. To examine this relationship, the kinematic parameters, hyperactivation, and intracellular cAMP content were evaluated in motile spermatozoa, obtained by discontinuous Percoll gradient and swim-up from 21 normozoospermic semen samples, incubated without and with PF for 0, 1, 2, and 4 h. PF increased beat cross frequency after 1 and 2 h of incubation, curvilinear velocity and lateral head displacement (ALH) after 4 h, and hyperactivation after 1, 2, and 4 h, and decreased linearity (LIN) after 1 h of incubation. The intracellular cAMP content of spermatozoa incubated with PF increased at all time-points examined. Both intracellular cAMP content and increase in hyperactivation in response to PF decreased with the length of incubation. In the absence of PF, cAMP content was unchanged and was correlated significantly only with ALH and the percentage of spermatozoa with hyperactivated motility. Following incubation with PF, cAMP content correlated with hyperactivation and all sperm kinematic parameters, with the exception of LIN and straightness. These findings suggest that the beneficial effects of PF on sperm kinematic parameters and hyperactivation are related to its ability to increase intracellular cAMP content.

Cyclic AMP↗
PubMed1998

Recovery of positive future thinking within a high-risk parasuicide group: results from a pilot randomized controlled trial.

OBJECTIVES: The research examined: (i) whether high risk parasuicide patients showed a deficit in positive future thinking but no increase in negative future thinking; and (ii) whether such a deficit could be remedied by a brief, manual-assisted psychological intervention (manual assisted cognitive-behaviour therapy; MACT). DESIGN: A cross-sectional, mixed model design was used to assess differences between a sample of high risk parasuicide patients and matched controls on future thinking. A longitudinal mixed model design was used to assess changes in future thinking in the different groups over time. METHODS: Parasuicide patients with a history of previous suicidal behaviour and personality disturbance were compared with a matched group of community controls on an adapted fluency measure of future thinking, which measured both quantitative and qualitative aspects of anticipated experiences. Patients were then randomly allocated to either the specific intervention (MACT) or treatment as usual (TAU) and assessed again at 6 month follow-up. RESULTS: Parasuicide patients showed reduced positive future thinking but no increased negative future thinking. Patients who received MACT showed a significant improvement in positive future thinking over the follow-up period whereas the TAU group showed no such improvement. However, interpretation of this finding was made more difficult by the control group also showing a significant improvement in positive future thinking. CONCLUSION: The results confirm that parasuicide patients exhibit a relative deficit in positive future thinking and suggest that this lack of positive future thinking may be remedied, at least partly, by a brief intervention.

Adolescent↗
PubMed1998

Androgen responsiveness of mouse kidney beta-glucuronidase requires 5'-flanking and intragenic Gus-s sequences.

Genetics studies of natural variants of the androgen response of mouse beta-glucuronidase (GUS) reveal a cis-active element closely linked to the GUS structural gene (Gus-s) that is necessary for this kidney-specific response. Results of our previous studies suggested sequences within or near an androgen-inducible deoxyribonuclease I-hypersensitive site (DH site) located in the ninth intron of Gus-s are associated with the androgen response of GUS. Using transgenic mice, we now demonstrate that at least two regions of sequence within Gus-s are involved in regulating the androgen response of GUS. The first, located within 3.8 kb of Gus-s 5'-flanking sequence, directs the response and its tissue specificity, while the second, located within a 6.4-kb fragment of Gus-s extending from the third through the ninth intron of Gus-s, protects the androgen responsiveness of the transgene from repressive influences of the insertion site.

Androgens↗
PubMed1997

Severe ovarian hyperstimulation syndrome: is it really preventable by prophylactic intravenous albumin?

OBJECTIVE: To evaluate the effectiveness of i.v. albumin in preventing severe ovarian hyperstimulation syndrome (OHSS) in patients at risk. DESIGN: Retrospective review and data analysis. SETTING: University-based tertiary referral center for assisted reproductive technologies (ART). PATIENT(S): Sixty women at high risk of developing severe OHSS after superovulation for ART. INTERVENTION(S): One liter of albumin (4.5%) administered i.v. during oocyte retrieval and immediately afterward. RESULT(S): Of the 60 women who had prophylactic i.v. albumin, 5 (8%) developed severe OHSS, which led to hospitalization. Eight (13%) developed moderate OHSS. Forty-seven (78%) did not develop any symptoms. Four of the 5 women who developed severe OHSS had ET and 3 of them (75%) were pregnant (1 twin and 2 singletons). CONCLUSION(S): Intravenous albumin administered at oocyte retrieval does not prevent the occurrence of severe OHSS, especially in cases associated with pregnancy. It is important that clinicians are not lured into a false sense of security by the early report, full of promise, on the use of i.v. albumin to prevent severe OHSS.

Albumins↗
PubMed1997

Q fever in pregnancy.

We describe a case of acute symptomatic infection with Coxiella burnetii acquired between the 16th and 28th week of pregnancy. Oral ciprofloxacin therapy was started on diagnosis, at the 28th week of pregnancy, but symptoms were unabated after 3 weeks treatment, suggesting persisting infection of the products of conception. Caesarean section was therefore performed at 32 weeks gestation when a healthy infant was delivered, and subsequent investigations showed no evidence of transplacental spread of infection. Infection control measures were applied at the time of delivery to minimize the risk of infection to obstetricians and midwives from potentially infectious products of conception.

Adult↗
PubMed1997

Sexual Risk Cognitions Questionnaire: a reliability and validity study.

The Sexual Risk Cognitions Questionnaire was designed to assess the type and frequency of cognitions associated with unsafe sex. It consists of 22 core items (SRCQ-22) with six subsections. Each subsection consists of 8-12 items designed for specific subgroups defined by gender, sexual orientation and HIV serostatus. Data on reliability and validity are presented based on a sample of 344 respondents in London. Reliability for all sections of the questionnaire was high but sample numbers were relatively small for some subsections. Validity for the SRCQ-22 was assessed in terms of its relationship with self-reported sexual behaviour among men who have sex with men who made up the largest proportion (70%) of the sample. The results indicate that the SRCQ-22 is a reliable measure for assessing cognitions related to HIV risk sexual behaviour in this population and supports the view that they are important determinants of safe and unsafe behaviour.

Adolescent↗
PubMed1997

Reasons given by patients for "non-progression' in HIV infection.

Identification of the reasons for long-term survival in HIV infection is an area of current intense research. The objective of this study was to determine the perceptions among patients with different rates of disease progression as to the reasons for a good outcome with HIV. In a case-control study of 134 long-term (> or = 8 years) HIV-infected participants, 62 were defined as non-progressors; current CD4 cell count > or = 500 x 10(6)/L and asymptomatic or only mildly symptomatic. Two groups of control patients were identified: intermediate progressors who also had been HIV-infected for > or = 8 years, but whose current CD4 cell count was < 500 x 10(6)/L (n = 61), and a group of rapid progressors who had developed AIDS within 5 years of HIV infection (n = 11). Non-progressors were asked 'what do you feel are the reasons for your good outcome with HIV-infection?' and intermediate and rapid progressors were asked 'what do you feel are the reasons for a good outcome with HIV infection?'. Mental attitude, and in particular a positive outlook was the reason most frequently given for a good outcome among both non-progressors (NP) 42%, and progressors (P) 40%, followed by lifestyle measures and personal action (NP 31%, P 35%). Medical treatments such as anti-retroviral drugs were rarely suggested (< 3%). No significant differences were observed in the frequency of the different reasons given by non-progressors and progressors. The belief among our long-term HIV-infected individuals, that a positive outlook, lifestyle and personal action are important determinants of a good prognosis, is in sharp contrast to the biomedical model of disease progression that prevails among the medical and scientific research community.

Acquired Immunodeficiency Syndrome↗
PubMed1997

'Curing' empty follicle syndrome.

We report a novel method of rescuing empty follicle syndrome (EFS) and provide evidence that it is a drug-related problem rather than a clinical dysfunction. In a preliminary study we established that in EFS the serum beta-human chorionic gonadotrophin (beta-HCG) concentrations 36 h after HCG administration never exceeded 10 mIU/ ml. beta-HCG concentrations were thus used to confirm EFS when oocytes were not retrieved from one ovary after controlled ovarian hyperstimulation. The procedure was suspended leaving intact all follicles in the second, ovary. After confirmation of EFS, a second HCG from a different batch was administered and 36 h later mature oocytes were retrieved from the intact ovary, suggesting a fault with the HCG previously administered. Three patients have been treated in this way. In the first case, four out of five mature eggs were fertilized after intracytoplasmic sperm injection (ICSI) resulting in the transfer of three top grade (grade 1) embryos. In the second case all seven mature oocytes fertilized after in-vitro fertilization (IVF) and three grade 1 embryos were transferred resulting in a twin pregnancy, now delivered. In the third case, five out of nine oocytes were fertilized after ICSI and one out of the three treated with high insemination concentration IVF fertilized, resulting in the transfer of three ICSI embryos.

Chorionic Gonadotropin↗
PubMed1997

The effect of the anaesthetic, Propofol, on in-vitro oocyte maturation, fertilization and cleavage in mice.

Propofol is a common anaesthetic agent used for oocyte retrieval procedures during in-vitro fertilization (IVF). The effect of Propofol in vitro on mouse oocyte maturation, fertilization and embryo cleavage was studied. In this study, 551 cumulus-free and 222 cumulus-enclosed oocytes from mice stimulated with pregnant mare's serum gonadotrophin (PMSG) were incubated for 30 min in medium containing 0, 100, 1000 or 10,000 ng/ml of Propofol prior to in-vitro maturation. Also, 325 cumulus-enclosed oocytes from mice stimulated to ovulate with PMSG/human chorionic gonadotrophin (HCG) were incubated for 30 min in similar concentrations of Propofol prior to IVF. Maturation, fertilization and cleavage rates were compared. A significant decrease in the in-vitro maturation rate was observed only when the cumulus-free and cumulus-enclosed oocytes were exposed to 10,000 ng/ml Propofol (P < 0.0074 and P < 0.0001 respectively). Fertilization and embryo cleavage rates were not significantly different compared with the controls. These findings give some reassurance with respect to human IVF. However, further studies on the potential effects of Propofol on implantation and pregnancy outcome following IVF are needed.

Anesthetics, Intravenous↗
PubMed1997

The prevalence and consequences of missed abortion in twin pregnancies at 10 to 14 weeks of gestation.

In singleton pregnancies at 10 to 14 weeks of gestation the prevalence of missed abortion is about 2%. In an ultrasound screening study at 10 to 14 weeks of gestation involving 492 twin pregnancies the prevalence of missed abortion was about twice as high as in singletons. The risk of subsequent miscarriage in twin pregnancies with one missed abortion was about ten times higher than in normal twin pregnancies. These findings may have important implications both in terms of counselling and for future research into the causes of miscarriage.

Abortion, Missed↗
PubMed1996

Predicting empty follicle syndrome.

OBJECTIVE: To determine a simple predictive test for empty follicle syndrome before oocyte retrieval. DESIGN: Retrospective correlation analysis. SETTING: Patients attending Nottingham University Research and Treatment Unit, a tertiary, university-based assisted reproductive technologies (ART) program between April 1, 1994 and March 31, 1995. PATIENT(S): Six women in whom no oocytes were retrieved after superovulation for ART (empty follicle syndrome) were compared with 11 women with successful oocyte retrieval. INTERVENTION(S): Subcutaneous buserelin acetate plus IM hMG and hCG were used for superovulation. Oocyte retrieval was transvaginal and ultrasound guided. MAIN OUTCOME MEASURE(S): Ultrasound measurement of follicular growth and serum E2 levels during superovulation. Serum beta-hCG levels before and 36 hours after hCG administration IM. Number of oocytes retrieved. RESULT(S): Before hCG administration, beta-hCG was not detectable in the serum. The serum beta-hCG 36 hours after hCG was 209 +/- 16.7 mIU/mL (conversion factor to SI units, 1.0; mean +/- SEM, range 106 to 290 mIU/mL) in women with successful oocyte retrieval and 4 +/- 1.8 mIU/mL (range 0 to 9 mIU/mL) in empty follicle syndrome. This difference was significant. CONCLUSION(S): Empty follicle syndrome is associated with very low bioavailability of beta-hCG and can be predicted by measuring serum beta-hCG level 36 hours after IM hCG administration.

Adult↗