Biomedical subjects

S Fishel

Publications and source records attributed to S Fishel.

At least 19 recordsLinked to original sources

PubMed2002

Preimplantation human embryos and embryonic stem cells show comparable expression of stage-specific embryonic antigens.

Cell-surface antigens provide invaluable tools for the identification of cells and for the analysis of cell differentiation. In particular, stage-specific embryonic antigens that are developmentally regulated during early embryogenesis are widely used as markers to monitor the differentiation of both mouse and human embryonic stem (ES) cells and their malignant counterparts, embryonic carcinoma (EC) cells. However, there are notable differences in the expression patterns of some such markers between human and mouse ES/EC cells, and hitherto it has been unclear whether this indicates significant differences between human and mouse embryos, or whether ES/EC cells correspond to distinct cell types within the early embryos of each species. We now show that human ES cells are characterized by the expression of the cell-surface antigens, SSEA3, SSEA4, TRA-1-60, and TRA-1-81, and by the lack of SSEA1, and that inner cell mass cells of the human blastocyst express a similar antigen profile, in contrast to the corresponding cells of the mouse embryo.

Animals↗

PubMed2001

Use of recombinant FSH and recombinant LH in multiple follicular stimulation for IVF: a preliminary study.

Twelve patients (17 cycles) who needed >3000 IU of recombinant FSH (rFSH) on previous follicular stimulation attempts for IVF using rFSH (group A) underwent further attempts (a total of 12 cycles) using rFSH supplemented with rLH from day 7 of stimulation (group B). There was no significant difference in the total quantitative administration of rFSH (mean: 4759 versus 4800 IU rFSH), days of stimulation (14.0 versus 12.6), number of M2 oocytes per patient (3.76 versus 4.17) or embryo morphology between group A and group B respectively. However, there was a significant increase in the incidence of fertilization (60.9 versus 86.0%; P = 0.006) and clinical (ongoing) pregnancies (1 versus 6; P = 0.022). The higher incidence of fertilization increased the mean number of embryos transferred per patient, although in this small group the data was not significant (1.75 versus 2.71). This preliminary clinical trial suggests that in poor responders superimposing rLH upon a down-regulated cycle stimulated with rFSH improves relevant outcome data; and this preliminary trial has encouraged the need for a larger and more detailed study.

Journal Article↗

PubMed2000

Fertility preservation of boys undergoing anti-cancer therapy: a review of the existing situation and prospects for the future.

With the advancement of medical science, most cancers in children are now treatable, the cure rate being almost 85%. In boys, one side effect of treatment (chemotherapy and radiotherapy) is destruction of the sperm precursor cells in the testis, resulting in the failure of sperm formation after puberty, and consequent infertility. At the time of anti-cancer treatment, future fertility of the boy patient is at the very bottom of the relative quality of life (RQL) parameters list; however, in adults infertility is an important issue following cure from cancer. In this article we have first reviewed the existing situation with regard to the state of the art of fertility preservation in young boys with cancer, and have then raised clinical and ethical issues and suggested a way forward. The review concludes with the emphasis that certain important issues still need to be resolved and, until these are, then the different techniques available should be confined to approved, ethical clinical trials where efficacy and safety can be fully evaluated.

Adolescent↗

PubMed2000

Should ICSI be the treatment of choice for all cases of in-vitro conception?

The objective of this study was to examine different clinical scenarios of in-vitro conception, viz. fertilization with conventional IVF, IVF with high insemination concentration (HIC) and intracytoplasmic sperm injection (ICSI), and assess on a sibling oocyte comparison the hypothesis that ICSI should be performed in all cases requiring in-vitro conception. ICSI with husband's spermatozoa had a higher incidence of fertilization as compared with IVF or IVF with HIC with donor spermatozoa (if previous failure of fertilization had occurred) for unexplained infertility. Similarly, ICSI with husband's spermatozoa had as high an incidence of fertilization as IVF with donor spermatozoa for patients with severe oligozoospermia, asthenozoospermia and/or teratozoospermia, even when the spermatozoa were not selected for their morphology. Two studies were performed to assess ICSI in potential oocyte-related failure of IVF, viz. when fertilization occurred in >50% of oocytes for one group of patients, and in <50% of oocytes in a second group. In both of these studies a significant proportion of the oocytes that failed to fertilize with conventional IVF eventually fertilized after ICSI. The overall conclusion was that ICSI as a first option offers a higher incidence of fertilization, maximizes the number of embryos and minimizes the risk of complete failure of fertilization for all cases requiring in-vitro conception. However, among other concerns, current knowledge of ICSI as an outcome procedure does not provide the confidence to use this process in all cases of IVF for the time being.

Female↗

PubMed2000

Comparison of sex chromosome aneuploidy in spermatozoa of fertile men and those requiring ICSI treatment detected by fluorescence in situ hybridization.

OBJECTIVE: To compare the frequencies of aneuploidy for chromosomes X, Y and 18 in spermatozoa of infertile and fertile males, using 3-color fluorescence in situ hybridization. METHODS: Twelve infertile patients who underwent intracytoplasmic sperm injection treatment at Queen's Medical Centre, Nottingham were studied. Three fertile men served as controls. Aneuploidy frequencies in both groups were compared using 2-sample t-tests. RESULTS: A total of 26,615 ad 93,649 cells were scored in the control and infertile groups respectively. The frequencies of diploidy, sex chromosome disomy and chromosome 18 disomy in the fertile (0.11, 0.28 and 0.11%) compared to the infertile males (0.05, 0.18 and 0.06%) were not statistically significantly different. CONCLUSION: Our preliminary data do not indicate an increased risk from paternal origin sex chromosome aneuploidies in ICSI. However, we recommend further investigations of the cytogenetic constitution of spermatozoa from severe male factor patients.

Adult↗

PubMed1999

Gamma-aminobutyric acid (GABA) A and B receptors mediate the stimulatory effects of GABA on the human sperm acrosome reaction: interaction with progesterone.

OBJECTIVE: To evaluate which gamma-aminobutyric acid (GABA) receptor mediates the stimulatory effects of this neurotransmitter on the human sperm acrosome reaction, and to examine the interaction of progesterone, a physiologic inducer of the acrosome reaction, with the GABA(A) receptor. DESIGN: Prospective study. SETTING: A university clinic of andrology. PATIENT(S): Men with normal sperm analysis parameters. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The acrosome reaction of motile spermatozoa. RESULT(S): The acrosome reaction was stimulated by GABA in a dose-dependent manner. This effect was inhibited completely by bicuculline, a GABA(A) receptor antagonist, and only partially by saclofen, a GABA(B) receptor antagonist. Accordingly, muscimol, a GABA(A) receptor agonist, stimulated the acrosome reaction to the same extent as GABA, whereas baclofen, a GABA(B) receptor agonist, was less effective. Preincubation with progesterone followed by the addition of GABA resulted in a significant increase in the percentage of acrosome-reacted spermatozoa compared with progesterone alone. However, this increase was less than a simple addition of effects, suggesting that GABA and progesterone act through the same receptor and/or use the same mechanism of action. To test this hypothesis, the ability of progesterone to induce acrosome reaction was tested in the presence of bicuculline, which suppressed the stimulatory effects of progesterone. Given that the GABA(A) receptor is linked to the chloride channel, we tested whether picrotoxin, a blocker of this channel, could modulate the effects of progesterone or GABA. Picrotoxin completely suppressed the acrosome reaction induced by progesterone and only partially suppressed that caused by GABA. CONCLUSION(S): gamma-Aminobutyric acid stimulated the acrosome reaction in human spermatozoa, acting mainly through the GABA(A) receptor and to a lesser extent through the GABA(B) receptor. Progesterone interacted with the GABA(A) receptor to induce the acrosome reaction, and the functional integrity of the chloride channel was vital for this effect.

Acrosome↗

PubMed1999

Morphology comparison of individually selected hyperactivated and non-hyperactivated human spermatozoa.

The objective of this study was to compare the morphology of human spermatozoa undergoing hyperactivated motility in vitro with those that were non-hyperactivated (non-hyp). Hyperactivation criteria were established by the Hobson Sperm Tracker (HST), sampling at 25 Hz, as curvilinear velocity (VCL) > or = 70 microns/s, amplitude of lateral head displacement (ALH) > or = 7 microns, linearity (LIN) < or = 30% and straight-line velocity (VSL) < or = 30 microns/s. Specially developed software incorporated in the HST produced a white computer-generated overlay for spermatozoa satisfying hyperactivation criteria. These spermatozoa, visually identified on a tracking monitor, were individually removed with micromanipulation equipment using a 12 microns-diameter needle. Fifty-six patient ejaculates were examined comprising a total morphological analysis of 1886 non-hyp spermatozoa and 1051 hyperactivated spermatozoa. Hyperactivated spermatozoa had a significantly higher mean percentage of normal heads and small acrosomes (P < 0.0001 and < 0.0001 respectively) and a significantly lower percentage of large and round heads, midpieces and tail defects (P = 0.002, < 0.0001, 0.02 and < 0.0001 respectively) when compared with non-hyp spermatozoa. These data demonstrate, for the first time, that a homogeneous live population of human hyperactivated spermatozoa, selected in vitro from patients with highly variable degrees of teratozoospermia, is comprised predominantly of cells with normal morphology (P < 0.0001).

Fertilization↗

PubMed1999

Evaluation of the fertilization potential of freshly isolated, in-vitro cultured and cryopreserved human spermatids by injection into hamster oocytes.

The clinical potential for fertilization was examined by using the human sperm-hamster oocyte assay system after microinjection of round (RS), elongating (ES) or elongated (EtedS) spermatids retrieved from obstructive and non-obstructive azoospermic patients. Freshly isolated, in-vitro cultured and cryopreserved spermatids were utilized. For each category of microinjected spermatids, we demonstrated that the more mature the injected spermatid, the higher the incidence of fertilization (for freshly isolated spermatids, P < 0.006 and P < 0.008, for in-vitro cultured spermatids, P < 0.007 and P < 0.007 and for cryopreserved spermatids, P < 0.006 and P < 0.007 for obstructive and non-obstructive azoospermic patients respectively). Short term in-vitro culture of the spermatogenic cells did not improve the incidence of fertilization. However, cryopreservation significantly decreased (P < 0.001) the incidence of fertilization when each corresponding spermatogenic cell stage was compared. The incidence of fertilization was not statistically different when corresponding stages of spermatogenic cells were compared from obstructive and non-obstructive patients.

Animals↗

PubMed1999

The incidence of spontaneous acrosome reaction in homogeneous populations of hyperactivated human spermatozoa.

The incidence of spontaneous acrosome reaction occurring in 1314 individually selected hyperactivated (HA) human spermatozoa was compared to that occurring in 8226 individually selected non-hyperactivated spermatozoa (non-HA) sampled over an incubation time course to allow for capacitation. Two-way analysis of variance showed a significant difference between HA and non-HA spermatozoa for the mean percent acrosome reacted (R), partially acrosome reacted (PR) and combined total (R+PR) (P < 0.001). One-way analysis showed that among the HA spermatozoa there were marked differences among the proportion showing R+PR at the various time points (P = 0.005). Using the same end point, there was no significant evidence of change with time for the non-HA spermatozoa. The overall data indicated that HA human spermatozoa have a greater propensity for spontaneous acrosomal loss than non-HA spermatozoa during incubation in synthetic culture media.

Acrosome Reaction↗

PubMed1999

Successful metaphase chromosome analysis of human elongated spermatids using mouse oocytes.

Human elongated spermatids from azoospermic patients were inserted into mouse oocytes by intracytoplasmic sperm injection (ICSI). The injection resulted in survival rates of 46.5% (180 out of 387) and activation rates of 36.1% (65 out of 180). The rate of two pronuclear (2PN) formation was 35.4% (23 out of 65). Only 34.8% (eight out of 23) metaphase chromosome spreads from 2PN zygotes could be analysed; however, all were of normal karyotype. Cytogenetic analysis at the first metaphase revealed that human elongated spermatid chromosomes were able to undergo replication in a heterogeneous environment.

Animals↗

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

Quantification of insulin-like growth factor I receptors on granulosa cells with flow cytometry after follicular stimulation.

The presence of insulin-like growth factor I (IGF-I) receptors on granulosa cells was investigated by flow cytometric analysis. Granulosa cells were retrieved from follicular fluid after oocyte retrieval during assisted reproduction technology procedures. Whole samples of follicular fluid were pooled and the cellular fraction analysed. In order to analyse granulosa cells only we developed a dual labelling technique whereby granulosa cells were identified as CD45 negative cells, distinguishing them from leukocytes which are CD45 positive. Analysis of the IGF-I receptor was done by staining the sample with a monoclonal anti-IGF-I receptor antibody (alphaIR3 clone) and goat anti-mouse phycoerythrin labelled antibody. After identification of the presence of IGF-I receptors, receptor expression was quantified by calibration of the fluorescence signals. We analysed 10 patients' samples and showed 559-1774 binding sites per granulosa cell with a mean value of 1125 +/- 382 (SD).

Female↗

PubMed1998

Short-term in-vitro culture and cryopreservation of spermatogenic cells used for human in-vitro conception.

Testicular cell suspensions were prepared from obstructive and non-obstructive azoospermic men and were cultured in vitro for 96 h as (i) mixed cell populations and (ii) isolated homogeneous populations of primary spermatocytes, round spermatids and elongating spermatids. The cells lost their viability gradually during the first 24 h period. By 72 h almost 90% of the cells were non-viable. Isolated pure fractions showed better viability at each time interval (P < 0.0005). Throughout the culture period primary spermatocytes, elongating spermatids and other non-spermatogenic cells showed no change in their morphology, but almost 22% of round spermatids showed growth of flagella. Most of the round spermatids developed their flagella during the first 4-8 h period of culture. Isolated pure round spermatids showed better flagellar growth compared with mixed cell suspensions (P < 0.0005). The spermatogenic cells were successfully cryopreserved. However, when mixed spermatogenic cell suspensions were cryopreserved, more cells lost their viability compared with when isolated pure fractions were cryopreserved (P < 0.0005).

Cell Survival↗

PubMed1998

Isolation, purification and assessment of viability of spermatogenic cells from testicular biopsies of azoospermic men.

The success of spermatid microinjection has generated many concerns. In particular, there is a lack of appropriate methodology for the isolation of large homogeneous populations of spermatids, with minimum loss of viability, from the testicular tissue of azoospermic men. Here we have compared two different isolation methods -- velocity sedimentation under unit gravity (VSUG) combined with discontinuous Percoll centrifugation (DPC), and separation with fluorescent-activated cell sorter (FACS) using light in the visible range -- to determine the most suitable method for the isolation of spermatids. Total mixed cell count/gram of testicular parenchyma was significantly higher in obstructive azoospermic men compared with non-obstructive azoospermic men (P < 0.001). The results of the comparison showed that in obstructive azoospermic patients the difference in the yields of primary spermatocytes produced by the two techniques was not significant, but for round and elongating spermatids the FACS separation proved to be the better method (P < 0.001). Similarly, in non-obstructive azoospermic patients, FACS separation proved to be superior, giving increased yields of primary spermatocytes and round and elongating spermatids compared with VSUG combined with DPC method (P < 0.001). More than 99 % of the separated cells retained their viability after FACS separation. As large homogeneous populations of viable spermatids can be separated with FACS in a relatively short period of time, FACS separation is the most suitable method for the isolation of spermatids from testicular biopsy tissue.

Cell Separation↗

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↗

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

In vitro fertilization for male infertility: when and how?

The first observation that in vitro fertilization (IVF) was useful for treating oligozoospermia and oligoasthenozoospermia was reported by Fishel and Edwards in 1982. This was followed by a series of cases indicating the value of IVF in such cases. Conventional IVF has been modified and refined to achieve increased rates of conception in cases of male factor infertility. Methods such as high insemination concentration IVF for the treatment of teratozoospermia and microscopic IVF for the treatment of oligozoospermia have had some impact on fertilization and pregnancy rates; however, reports of success are varied. The recent advent of micromanipulation and, in particular, intracytoplasmic sperm injection (ICSI) has overshadowed the use of these modified IVF procedures. Because of the high fertilization and pregnancy rates achieved with ICSI, other micromanipulation techniques (subzonal insemination and partial zona dissection) have been abandoned; there have also been suggestions that other more conventional techniques, i.e. IVF, should also be abandoned and that ICSI become the sole technique for the treatment of infertility. The rapid increase in the number of centres using ICSI has led to extreme pressure for individual units to achieve high fertilization and pregnancy rates and there is a temptation to assign all patients to ICSI treatment. It is important that, in this highly competitive environment, new techniques are not applied haphazardly and reduced to the mere injection of gametes and achievement of pregnancy regardless of the cause of infertility. In his 1986 IVF--Historical Perspective, Fishel quoted Auguste Comte: 'to understand science it is necessary to know its history'. IVF has much recent history in animal and also human work. Although ICSI is the most significant therapeutic advance in male infertility treatment, its application to human IVF is only 4 years old, with a paucity of animal studies on which to rely. For this reason IVF still plays a very important role in the treatment of male factor infertility and should only be ruled out when it has failed previously or the number of available sperm is limited.

Decision Making, Computer-Assisted↗

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↗