E A Lenton

The University of Sheffield, Sheffield, England, United Kingdom

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Publications (105)317.04 Total impact

    Annals of the New York Academy of Sciences 12/2006; 541(1):498 - 509. DOI:10.1111/j.1749-6632.1988.tb22286.x · 4.38 Impact Factor
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    ABSTRACT: The distribution of the length of the luteal phase was investigated in 187 women with regular, apparently ovulatory menstrual cycles of whom 95 had unexplained infertility and the other 92 comprised a group of healthy volunteer subjects. If the short luteal phase is associated with infertility it might be expected t o occur more frequently in women with unexplained infertility. A short luteal phase (defined as a luteal phase lasting ≤ 11 days) was found in 9% of the infertile group and in 8% of the normal group showing that these cycles do not occur more frequently in women with infertility.
    BJOG An International Journal of Obstetrics & Gynaecology 08/2005; 91(11):1120 - 1122. DOI:10.1111/j.1471-0528.1984.tb15087.x · 3.45 Impact Factor
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    S D Keay · E A Lenton · I D Cooke · M.G.R. Hull · J M Jenkins
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    ABSTRACT: Cancellation of assisted conception cycles because of poor ovarian response to gonadotrophins is a significant problem in assisted reproduction. Various adjuvant treatments have been suggested to improve responsiveness. This study reports on the potential benefits of low dose dexamethasone. Patients <40 years of age were invited to participate in a twin centre prospective double blind randomized placebo controlled study. A total of 290 patients were recruited and computer randomized using sealed envelopes to receive either 1 mg dexamethasone (n = 145) or placebo tablets (n = 145) in addition to a standard long protocol gonadotrophin-releasing hormone analogue with gonadotrophin stimulation regime. A significantly lower cancellation rate for poor ovarian response was observed in the dexamethasone group compared with controls (2.8 versus 12.4% respectively, P < 0.002). Further comparisons between the dexamethasone group and controls were made of median fertilization rates (60 versus 61% respectively, NS), implantation rates (16.3 versus 11.6% respectively, NS) and pregnancy rate per cycle started (26.9 versus 17.2%, NS). The benefit was apparent in patients both with polycystic and normal ovaries. Low dose dexamethasone co-treatment reduces the incidence of poor ovarian response. It may increase clinical pregnancy rates and should be considered for inclusion in stimulation regimes to optimize ovarian response.
    Human Reproduction 10/2001; 16(9):1861-5. · 4.57 Impact Factor
  • P Y Tay · EA Lenton
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    ABSTRACT: To assess a range of exogenous HCG regimes designed to simulate the endocrine environment occurring in biochemical, single and multiple pregnancies and to study the response of the corpus luteum to those regimes. Prospective clinical study. Twenty-five normally cycling women aged 24-35 years were given one of four regimes of HCG injections designed to mimic the HCG concentrations found following spontaneous implantation. Regimes A, B, C and D were designed with starting HCG doses of 60, 140, 250 and 1000 iu, respectively. The daily HCG injections were then increased to give a doubling concentration every 30 h for regime A, every 27 h for regime B, every 24 h for regimes C and D. HCG administration was started on either days 7 or 8 after the LH peak. Plasma HCG and progesterone concentrations. Subjects given regime A failed to demonstrate any rescue of the corpus luteum despite low-detectable amounts of HCG in the circulation equivalent to those seen in some biochemical pregnancies. In contrast, subjects given regimes B and C demonstrated prompt increases in progesterone secretion immediately after the first HCG injection achieving HCG and progesterone concentrations in plasma similar to those seen in normal singleton pregnancies. Subjects given regime D also showed rapid rescue of the corpus luteum but this time achieved plasma HCG concentrations in the range normally seen in multiple pregnancies. All subjects in regimes B, C and D secreted significantly higher amounts of progesterone than those in regime A (P<0.001). However, despite the greater amounts of HCG used in regime D, the amount of progesterone produced was not significantly different from regimes B or C. The exogenous HCG regimes used in this study successfully mimicked the hormonal environment found in biochemical, single and multiple pregnancies and elicited appropriate corpus luteum responses.
    Clinical Endocrinology 09/2000; 53(3):345-50. DOI:10.1046/j.1365-2265.2000.01075.x · 3.46 Impact Factor
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    P Y Tay · E A Lenton
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    ABSTRACT: Our purpose was to study the optimum time to administer exogenous human chorionic gonadotropin (hCG) to rescue the human corpus luteum during the luteal phase of normal menstrual cycles. Groups of normally cycling women were given 4-day regimes of exogenous hCG by daily injection beginning 4 (Group A), 8 (Group B), and 12 (Group C) days after the midcycle luteinizing hormone surge. The hCG regime used was designed to mimic hCG levels following a spontaneous implantation. All subjects acted as their own controls in a preceding normal menstrual cycle. Group A subjects exhibited patterns and levels of salivary progesterone concentration similar to those seen in the control cycles throughout the normal luteal phase. In contrast, subjects in both Group B and Group C demonstrated a rapid and sustained increase in progesterone production following the hCG injections. Furthermore, subjects in Group B achieved the highest mean peak progesterone concentrations and the total amount of salivary progesterone secreted was significantly higher than in the control cycles (P < 0.05). Although the mean luteal-phase length was greatest in Group C, the response of the corpus luteum was suboptimal, with a delayed rise in salivary progesterone. These data show that the qualitative and quantitative response of corpus luteum to an early pregnancy-type hCG signal is maximal around the midluteal phase, coincident with the time of implantation.
    Journal of Assisted Reproduction and Genetics 11/1999; 16(9):495-9. DOI:10.1023/A:1020507217897 · 1.72 Impact Factor
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    F Zayed · EA Lenton · I D Cooke
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    ABSTRACT: A prospective trial was undertaken to evaluate the efficacy of stimulated in-vitro fertilization (SIVF) and stimulated intrauterine insemination (SIUI) in couples with unexplained and mild male factor infertility. In all, 80 couples were allocated to treatment with SIVF or SIUI, both treatments following the same protocol [clomiphene citrate and follicle stimulating hormone (FSH) injection], except that higher doses of FSH were used in the SIVF treatment cycles. Initially, 41 couples were allocated to and started treatment with SIVF but eight cases were eventually converted to SIUI because of under-response. Similarly, although 39 couples were initially allocated to SIUI treatment, five of these converted to SIVF because of over-response. The treatment cycles that were converted either to SIUI or to SIVF were not considered as treatment failures but as treatment changes and so were included in the analyses. Of the final 38 SIVF cycles, four were cancelled (dysfunctional response), failed fertilization occurred in five cycles and 29 subjects reached embryo transfer. There were two biochemical pregnancies [positive human chorionic gonadotrophin (HCG) only], two clinical abortions and seven live births. Of the final 42 SIUI cycles, only two were cancelled, insemination being performed in the remaining 40 cases. The result was one clinical abortion, three ectopics and eight live births. The proportion of cycles with positive HCG was identical (28.9% per cycle treated for SIVF and 28.6% for SIUI) and the livebirth rates were also not different (18.4% per cycle treated for SIVF and 19.0% for SIUI). The cost per maternity of SIUI was approximately half that of SIVF (Pounds Sterling 1923 versus Pounds Sterling 4611) and so we conclude that, as SIUI had an efficacy that was not significantly different from SIVF (using similar protocols) but was more cost-effective, it must be considered the more appropriate form of management for the treatment of unexplained and mild male factor infertility. Indeed, it is hard to justify the routine use of IVF, as a first approach, in unexplained infertility.
    Human Reproduction 12/1997; 12(11):2408-13. DOI:10.1093/humrep/12.11.2408 · 4.57 Impact Factor
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    F Zayed · E.A. Lenton · I.D. Cooke
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    ABSTRACT: This study evaluated outcome in 117 couples with unexplained infertility who underwent 162 attempts at natural cycle in-vitro fertilization (NIVF) between 1991 and 1993. An egg was obtained in 138 cycles and a single embryo was transferred in 89 cycles. There were 16 implantations (four biochemical pregnancies, three clinical abortions and nine live births). The implantation rate per embryo was 16/89 (18.0%), which translated into a live birth rate per egg collection of 9/138 (6.5%). The impact factors that were assessed included oocyte quality, sperm quality, embryo quality and woman's age. The outcome measures used were fertilization/inseminated egg and implantation/replaced embryo. All embryo transfers were of single embryos. We conclude that, in couples with unexplained infertility, outcome following NIVF is affected by both egg and sperm quality and by the age of the woman. Embryo quality was independent of the above factors but was also critical for successful implantation.
    Human Reproduction 12/1997; 12(11):2402-7. DOI:10.1093/humrep/12.11.2402 · 4.57 Impact Factor
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    A Kumar · P Benny · E A Lenton · I D Cooke
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    ABSTRACT: Two modes of embryo transfer, uterine and tubal, were compared following natural cycle in-vitro fertilization (IVF). Only patients with patent Fallopian tubes were included in the study. Tubal embryo transfer was performed by retrograde tubal cannulation without analgesia on an outpatient basis. Tubal transfer conferred no benefit compared with uterine transfer in male factor infertility with positive fertilization (pregnancy rates of 15.8% in both groups). Although tubal embryo transfer in the patients with unexplained infertility improved the pregnancy rates from 7.8% in uterine transfer (5/64) to 17.6% in the tubal transfer group (13/74), this improvement was not statistically significant.
    Human Reproduction 04/1997; 12(3):484-6. DOI:10.1093/humrep/12.3.484 · 4.57 Impact Factor
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    ABSTRACT: Young women with unexplained infertility who exhibit elevated basal serum follicle stimulating hormone (FSH) concentrations (>10 IU/l) have poor outcomes in in-vitro fertilization. A subgroup of these women has regular menses, representing 'subclinical' ovarian failure, which may have an autoimmune basis and could potentially be treated by immunosuppression. To investigate this further, a range of immunological markers was used to assess autoimmune activity in 14 women aged <40 years with elevated FSH compared with 15 infertile women with normal FSH and 10 pre-menopausal, healthy controls. All samples were taken during natural menstrual cycles. Organ-specific antibodies against ovary, endometrium and thyroid, and non-organ-specific antibodies against histones and cardiolipin, were not significantly increased in elevated FSH patients compared with other control groups. Soluble CD23 and soluble intercellular adhesion molecule concentrations were not elevated in the sera of the women tested, and circulating T cell subsets remained unaltered. Significantly, increased concentrations of the complement breakdown product C3a and terminal complement complexes were detected in the elevated FSH group compared with the normal FSH group, although the latter also had significant complement activation compared with laboratory controls. Autoimmunity appears as an infrequent cause of 'subclinical' ovarian failure, but there is evidence of activation of complement in the sera of infertile women.
    Human Reproduction 03/1997; 12(2):244-9. DOI:10.1093/humrep/12.2.244 · 4.57 Impact Factor
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    K Turner · EA Lenton
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    ABSTRACT: Co-culture of human embryos with cell layers has generally shown that blastocyst formation rates are improved compared to routine culture in medium alone. In order to assess this further, we have additionally classified resulting blastocysts according to their morphology and secretion of human chorionic gonadotrophin (HCG). A total of 70 supernumerary human embryos from 15 patients were divided equally and randomly between two culture conditions: (i) co-culture with Vero cells; and (ii) culture in our routine medium. Embryo development and morphology were recorded for up to 14 days in culture. The results showed that embryos on Vero cells had a significantly higher blastocyst formation rate (P < 0.02) by or on day 6 of development than those in routine culture medium alone (77 and 46% respectively). For HCG analysis, the culture medium was changed in both culture systems on days 5, 7, 9, 12 and 14 of embryo development and analysed. Most embryos began to produce HCG between days 7 and 9, with HCG secretion being significantly higher from embryos on Vero cells between days 9 and 12 than from embryos in routine culture (P < 0.03). The morphology of the blastocysts obtained was related to their ability to hatch and produce HCG but was not significantly better for one type of culture system than for the other.
    Human Reproduction 09/1996; 11(9):1966-74. · 4.57 Impact Factor
  • K. Turner · E.A. Lenton
    Human Reproduction 09/1996; 11(9):1966-1974. DOI:10.1093/oxfordjournals.humrep.a019526 · 4.57 Impact Factor
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    A Dhar · P Dockery · W S O · K Turner · EA Lenton · I D Cooke
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    ABSTRACT: The human ovarian granulosa cell is perhaps the most widely studied endocrine cell, but little quantitative structural information exists for this cell. In the present study new and traditional stereological probes have been employed to provide quantitative structural information on these functionally important cells. Granulosa cells were obtained from follicular aspirations from 10 women during in vitro fertilisation procedures. Initially 2 methods were used to estimate the mean nuclear volume of these cells: the mean number weighted nuclear volume was estimated by the Selector and the mean volume weighted nuclear volume by the point sampled intercept method. It was found that the difference between the 2 volume estimates was only 8.5%. The volume weighted mean nuclear volume was used as an estimate of nuclear volume. This was subsequently corrected (taking the percentage difference as the empirical bias) and combined with fractional cell volumes (Vv) to produce estimates of cell, mitochondrial, lipid and nucleolar volume. The proportion of the cell occupied by the nucleus had a remarkably low interindividual variation (CV = 7.6%). The proportion of the nucleus occupied by euchromatin also had a striking low variation (CV < 6%). All other cellular parameters had CVs of less than 35%. The lipid composition of these cells showed the greatest interindividual variability, with a CV of 42% for relative and 54% for absolute volume. The present study outlines a simple protocol for the quantitation of granulosa cell structure using new unbiased stereological probes and providing baseline structural information.
    Journal of Anatomy 06/1996; 188 ( Pt 3)(3):671-6. · 2.10 Impact Factor
  • Ahmed N. A. Ebbiary · I D Cooke · E A Lenton
    Menopause 01/1996; 3(4):251-252. DOI:10.1097/00042192-199603040-00101 · 3.36 Impact Factor
  • Ahmed N. A. Ebbiary · E A Lenton · I D Cooke
    Menopause 01/1996; 3(4):252. DOI:10.1097/00042192-199603040-00102 · 3.36 Impact Factor
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    ABSTRACT: During development of the dominant follicle, the avascular granulosa cells and oocyte are exposed to the follicular fluid endocrine microenvironment. An alteration in the endocrine characteristics of follicular fluid affects follicular steroidogenesis, oocyte maturation, ovulation and subsequent corpus luteum function. In-vitro studies on pooled follicular fluid from ovarian specimens lacked temporal precision between menstrual and follicular endocrine events. We have established a new technique, termed folliculocentesis (FC), to sample follicular fluid from the dominant ovarian follicle without compromising its growth or function during the mid- to late follicular phase. A total of 38 subjects with regular ovulatory cycles each underwent two identical cycles of hormone and follicle growth monitoring: one cycle served as the control, and FC was performed during the second cycle. During all cycles, plasma luteinizing hormone (LH), oestradiol and ultrasound monitoring of follicle growth were commenced on day 7 and continued until after ovulation. During FC cycles, 200 microliters of follicular fluid were aspirated from the dominant follicle using transvaginal ultrasound guidance when the follicle diameter reached > or = 10 mm. Six subjects were excluded from the study because of incomplete or invalid endocrine data. In all, 32 subjects completed both the FC and control cycles. The follicle growth pattern, maximum follicle diameter, plasma oestradiol, oestradiol peak, plasma LH, LH surge and follicular phase length were similar during FC and control cycles. A total of 50 valid follicular fluid samples were obtained when the dominant follicle was sampled once, twice or three times during the same cycle and from the same follicle in 15, 16 and one subjects respectively. The follicular fluid samples contained steroid concentrations consistent with those of the mid- to late follicular phase. We conclude that the FC procedure is safe, easy to perform and does not affect follicle growth or hormone dynamics. Analysis of the follicular fluid samples is expected to provide us with valuable in-vivo information about ovarian endocrinology.
    Human Reproduction 09/1995; 10(9):2325-33. · 4.57 Impact Factor
  • Human Reproduction 09/1995; 10(9):2325-2333. DOI:10.1093/oxfordjournals.humrep.a136294 · 4.57 Impact Factor
  • K Turner · K L Martin · B J Woodward · E A Lenton · H J Leese
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    ABSTRACT: The uptake of pyruvate by human embryos derived from natural cycles in the first 24 h following fertilization was examined. Since only one egg was obtained and therefore only one embryo transferred to the woman, it was possible to relate pyruvate consumption by a particular embryo to the outcome of that cycle (pregnancy or no pregnancy). The results showed that embryos have a wide range of pyruvate uptake values (2-53 pmol/embryo/h) but that this variation was reduced significantly to an intermediate range of values in those embryos that were able to implant (10-30 pmol/embryo/h). An association was found between embryo morphology and pyruvate consumption. Morphologically good embryos were more likely to implant if they demonstrated an intermediate pyruvate uptake. However, poor embryos did not implant even if they had a pyruvate uptake of 10-30 pmol/embryo/h. No relationship was found between the type of infertility and pyruvate consumption of individual embryos. It is suggested that the ability of an embryo to implant is multifactorial and that both morphology and pyruvate uptake may be factors.
    Human Reproduction 01/1995; 9(12):2362-6. · 4.57 Impact Factor
  • B J Woodward · E A Lenton · K Turner · W F Grace
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    ABSTRACT: Of 593 bipronucleate eggs allowed to develop in vitro, 275 (46%) achieved the blastocyst stage and beyond, 124 (21%) initiated hatching, but only 49 (8%) fully hatched. About half of the pre-embryos (48%) which developed to these more advanced stages were incapable of secreting significant amounts (> 200 microIU) of cumulative human chorionic gonadotropin (HCG) up to day 14. HCG production does not appear to begin until the expanded stage and is independent of hatching. Assessing cleavage rate through successive stages and morphological grades up to the 8-cell stage had little bearing on the ability of a pre-embryo to hatch or secrete HCG. Progression through the stages of preimplantation development in vitro does not always appear to be accompanied by the necessary biochemical stages. If only 46% of pre-embryos with two pronuclei are capable of achieving the blastocyst stage, and of these only 52% are capable of secreting HCG, then it follows that only 24% of the original bipronucleate pre-embryos in vitro can be considered anatomically and biochemically competent. However, this is only applicable for pre-embryos not transferred or frozen, and is thus subject to a selection bias. Inability to detect HCG in vitro is not conclusive proof that a pre-embryo is developmentally incompetent. Similarly failure to hatch in vitro may not be taken as definitive evidence that hatching would have failed had fertilization and development been completed in vivo. Nevertheless, if pre-embryonic development in vitro is similar to that in vivo, this may be a contributory factor in the low pregnancy rates following in-vitro fertilization treatment.
    Human Reproduction 11/1994; 9(10):1909-14. · 4.57 Impact Factor
  • N. A. Ahmed Ebbiary · EA Lenton · I D Cooke
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    ABSTRACT: Reproductive ageing is associated with reduced fertility and endocrine changes that become more pronounced during the perimenopausal period. We aimed to assess changes in gonadotrophin concentrations and the onset of these changes during the reproductive life prior to the perimenopause. Ovarian and pituitary hormones were measured and follicle growth monitored in 500 regularly cycling infertile women aged 20-44 years. Serum levels of FSH and LH were determined during the follicular phase and ultrasonography was used to monitor follicle growth and ovulation. The luteal phase was assessed by salivary progesterone measurements. Changes in basal FSH and LH with age during ovulatory cycles were assessed. There was a significant progressive increase in FSH levels as early as age 29-30 years which was continued throughout the 30s and became more marked in the early 40s. LH levels showed significant increase at the age of 35-36 years which was maintained till the age of 40 years and followed by a further increase in women aged > 40 years. An increase in FSH and LH concentrations can be detected in women with regular ovulatory cycles quite early during the reproductive life. The increase in basal FSH (and later LH) may represent the earliest endocrine marker of reproductive ageing. These age-related increases in FSH and LH can be used as hormonal markers to counsel patients as to the likelihood of their reproductive potential.
    Clinical Endocrinology 09/1994; 41(2):199-206. DOI:10.1111/j.1365-2265.1994.tb02530.x · 3.46 Impact Factor
  • I D Cooke · E A Lenton
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    ABSTRACT: Natural cycle IVF (NIVF) arose from a wish to understand intrafollicular events in couples with unexplained infertility. Single follicle aspiration required unusual technical skill and a precise understanding of the endocrinology in the ostensibly normal cycle. The application of NIVF to all candidates for assisted conception resulted in a low delivery rate. However once data had accumulated it became apparent that age, follicular phase FSH concentrations and other endocrine abnormalities were associated with high failure rates. The concept of using NIVF as a preliminary screening cycle arose. By early elimination of some candidates and selective inclusion of others a highly cost effective regime can be developed. Taking delivery rates into account the cost per maternity is only half that of stimulated IVF. Using clear cut algorithms for the investigation of different categories of infertility the place of NIVF can be defined. Current UK discussions relate to exclusions from access to IVF. Biological exclusions such as age could further enhance the cost effectiveness of NIVF. When NIVF can contribute to at least 50% of cycles in an assisted conception programme it has the potential to have a major economic impact.
    Australian and New Zealand Journal of Obstetrics and Gynaecology 07/1994; 34(3):268-71. DOI:10.1111/j.1479-828X.1994.tb01071.x · 1.51 Impact Factor

Publication Stats

2k Citations
317.04 Total Impact Points


  • 1977–2001
    • The University of Sheffield
      • Department of Biomedical Science
      Sheffield, England, United Kingdom
  • 1994
    • BMI The Priory Hospital in Birmingham
      Birmingham, England, United Kingdom