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Dive into the research topics where Amanda J. Tozer is active.

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Featured researches published by Amanda J. Tozer.


Reproductive Biology and Endocrinology | 2010

Estradiol, progesterone, testosterone profiles in human follicular fluid and cultured granulosa cells from luteinized pre-ovulatory follicles

Xuesong Wen; Dong Li; Amanda J. Tozer; Suzanne M. Docherty; Ray K. Iles

BackgroundThe production of sex steroids by follicular cells is proposed to be influenced by the maturity of the incumbent oocyte. Thus steroid levels may reflect suitability of an oocyte for IVF. We examined follicular fluids and granulosa cell production of steroid from IVF patients in order to test the relationship between steroid levels and fertilization.MethodsFollicular fluid and granulosa cells were extracted from 206 follicles of 35 women undergoing controlled ovarian stimulation. Follicular fluid was assayed for estradiol, progesterone and testosterone. Granulosa cells were cultured from individual follicles and their culture media assayed for production of these hormones after 24 hrs in vitro. Levels of steroids were correlated with follicular diameter, oocyte recovery and subsequent fertilization.ResultsFollicular fluid levels of progesterone were 6100 times higher than that of estradiol, and 16,900 times higher that of testosterone. Despite the size of follicle triggered after controlled luteinisation, the levels of progesterone and testosterone were maintained at relatively constant levels (median 98.1 micromoles/L for progesterone, and 5.8 nanomoles/L for testosterone). However, estradiol levels were slightly lower in the larger follicles (follicular diameter 10-15 mm, median 25.3 nanomoles/L; follicles > = 15 mm, median 15.1 nanomoles/L; linear correlation r = -0.47, p < 0.0001). With respect to oocyte recovery, no steroid showed a significant association in follicular fluid levels. Similarly no difference in follicular fluid steroid levels was found for those oocytes that did or did not fertilize. Significant quantities of progesterone were produced by the granulosa cells but production was constant regardless of the size of follicle from which the cells originated. Estradiol levels were only detectable in 10 of 121 cultures examined, and testosterone in none. Interestingly, when an oocyte was present follicular estradiol levels correlated with progesterone levels. However, when absent, follicular estradiol levels correlated with testosterone levels but not with progesterone.ConclusionsThe principle steroid product of luteinized pre-ovulatory granulosa is progesterone, a differentiation triggered by the gonadotropin surge. However, absolute steroid levels are associated with follicular size, not oocyte maturation/ability to fertilize.


Journal of Chromatography B | 2009

Capillary electrophoresis of human follicular fluid

Xuesong Wen; David Perrett; P. Patel; Naijun Li; Suzanne M. Docherty; Amanda J. Tozer; Ray K. Iles

Some of the major serum proteins that are also found in follicular fluid, including transferrin, alpha-macroglobulin and albumin, are thought to play a role in oocyte maturation. This study set out to identify proteins in human follicular fluid by capillary zone electrophoresis and to investigate their relationship to follicular/oocyte maturity and fertility outcome. 176 individual follicular fluid samples, from 30 women undertaking in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), were run using an optimized capillary zone electrophoresis method that gave a good separation of sixteen peaks in most samples. Nine of the peaks were identified and quantified but seven remain unknown and require further proteomic identification. Of the identified protein peaks, levels of each were corrected for follicular volume and total content calculated. No significant difference in protein levels was found with regard to oocyte recovery and fertilization. Protein concentrations tended to decrease as the follicular sphere increased whilst total content in follicular fluid increased in proportion to size. This is consistent with simple transudation across a sphere surface area which does not increase in proportion to the follicular fluid. This is not true of the concentration and content pattern of other proteins/biomolecules which are produced by follicular cells locally. In conclusion, neither concentration nor absolute levels of nine major proteins identified in follicular fluids correlated with oocyte presence and fertility outcome. Future work to remove more concentrated proteins (e.g. albumin) would enhance separation of smaller peaks and identification of the unknown molecules.


Reproductive Biology and Endocrinology | 2007

Does measuring early basal serum follicular lutinising hormone assist in predicting In vitro fertilization (IVF)/Intracytoplasmic sperm injection (ICSI) outcome?

Ahmed S. Kassab; Luca Sabatini; Gidon Lieberman; Amanda J. Tozer; Ariel Zosmer; Colin Davis; Talha Al-Shawaf

BackgroundThe aim was to examine the correlation of early follicular serum lutinising hormone (LH) and the clinical outcome of assisted reproduction technique (ART).MethodsAn observational study included 1333 consecutive women undergoing invitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). 964 women were having their first cycle of ART. Data were entered prospectively. All women had serum LH measured in the 6 months before the index cycle studied. No repeat cycles were included. The main outcomes measured were clinical pregnancy (CP) and live birth (LB) correlation to serum LH. Forward multivariate stepwise regression analysis was applied, and other statistical tests were used as appropriate.ResultsThere was non significant correlation between basal serum LH and CP and LB in the polycystic ovary syndrome group (R2 = 0.02, F = 1.7 and P = 0.76) (R2 = 0.01, F = 2.6 and P = 0.77) respectively after adjusting for age, BMI, day of oocyte retrieval, starting dose, total dose of stimulation, type of gonadotrophin used, number of oocytes retrieved, fertilization rate and number of embryos transferred. Other aetiological causes group there was similarly non significant correlation between basal serum LH and CP (R2 = 0.05, F = 13.1 and P = 0.66), nor for LB (R2 = 0.007, F = 4.5 and P = 0.9).ConclusionEarly follicular serum LH measurements in the 6 months before IVF/ICSI treatment cycle did not correlate with the clinical pregnancy or the live birth rate.


International Journal of Endocrinology | 2012

Serum FSH Levels in Coasting Programmes on the hCG Day and Their Clinical Outcomes in IVF ± ICSI Cycles

Srisailesh Vitthala; Jerome Bouaziz; Amanda J. Tozer; Ariel Zosmer; Talha Al-Shawaf

Introduction. Coasting is the most commonly used strategy in prevention of severe OHSS. Serum FSH levels measurements during coasting may aid in optimizing the duration of coasting. Objective(s). To study live birth rates (LBRs), clinical pregnancy rates (CPRs), and optimal duration of coasting based on serum FSH levels on the hCG day. Materials and Methods. It is a retrospective study performed between 2005 and 2008 at Barts and The London Centre for Reproductive Medicine, NHS Trust, London, UK, on 349-coasted women undergoing controlled ovarian stimulation (COS) for IVF ± ICSI. The serum FSH level measurements on the hCG day during coasting programme were analysed to predict the LBR and CPR. Result(s). LBR and CPR were significantly higher when the FSH levels on the hCG day were >2.5 IU/L (LBR: 32.5%, P = 0.045 and CPR: 36.9%, P = 0.027) compared to FSH <2.5 IU/L. The optimal FSH cut-off level for LBR and CPR is 5.6 IU/L on the hCG day. The optimal cutoff for coasting is 4 days. Conclusion(s). Coasting may be continued as long as either serum FSH level is > 2.5 IU/L on the hCG day without compromising the LBR and CPR or to maximum of 4 days.


Human Reproduction | 2001

Prevention of severe ovarian hyperstimulation syndrome in IVF with or without ICSI and embryo transfer: a modified `coasting' strategy based on ultrasound for identification of high-risk patients

T. Al-Shawaf; A. Zosmer; S. Hussain; Amanda J. Tozer; N. Panay; C. Wilson; A.M. Lower; J.G. Grudzinskas


Human Reproduction | 2004

The effects of ‘coasting’ on follicular fluid concentrations of vascular endothelial growth factor in women at risk of developing ovarian hyperstimulation syndrome

Amanda J. Tozer; Ray K. Iles; E. Iammarrone; C.M.Y. Gillott; T. Al-Shawaf; J.G. Grudzinskas


Fertility and Sterility | 2006

Follicular fluid levels of inhibin A, inhibin B, and activin A levels reflect changes in follicle size but are not independent markers of the oocyte’s ability to fertilize

Xuesong Wen; Amanda J. Tozer; Stephen A. Butler; Celia M. Bell; Suzanne M. Docherty; Ray K. Iles


Human Reproduction | 2001

Does laparoscopic ovarian diathermy affect the outcome of IVF-embryo transfer in women with polycystic ovarian syndrome? A retrospective comparative study.

Amanda J. Tozer; T. Al-Shawaf; A. Zosmer; S. Hussain; C. Wilson; A.M. Lower; J.G. Grudzinskas


Human Reproduction | 2002

Value of measuring serum FSH in addition to serum estradiol in a coasting programme to prevent severe OHSS

T. Al-Shawaf; Ariel Zosmer; Amanda J. Tozer; C. Gillott; A.M. Lower; J.G. Grudzinskas


Metabolism-clinical and Experimental | 2010

High follicular fluid adenosine levels may be pivotal in the metabolism and recycling of adenosine nucleotides in the human follicle

Xuesong Wen; David Perrett; Nicola Jones; Amanda J. Tozer; Suzanne M. Docherty; Ray K. Iles

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T. Al-Shawaf

St Bartholomew's Hospital

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A.M. Lower

St Bartholomew's Hospital

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Ariel Zosmer

Queen Mary University of London

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C. Wilson

Royal London Hospital

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Ahmed S. Kassab

Queen Mary University of London

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David Perrett

Queen Mary University of London

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