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Biomedical subjects

M Alikani

Publications and source records attributed to M Alikani.

At least 37 records · Page 2Linked to original sources
PubMed1995

Chromosomal status of uni-pronuclear human zygotes following in-vitro fertilization and intracytoplasmic sperm injection.

Uni-pronuclear embryos (n = 42) were analysed by fluorescence in-situ hybridization (FISH) with two to four chromosome pair-specific probes. Half of these embryos resulted from conventional insemination and half from intracytoplasmic sperm injection (ICSI). The majority of uni-pronuclear embryos from conventional insemination were normally diploid (61.9%) whereas only 9.5% of uni-pronuclear ICSI embryos (P < 0.001) were diploid. In addition, a significantly higher number of uni-pronuclear embryos from conventional insemination had a Y chromosome (10/21, 47.6%) when compared with ICSI embryos (2/21, 9.5%) (P = 0.015). It is concluded that the majority of uni-pronuclear embryos following regular in-vitro fertilization are fertilized, whereas those from ICSI are parthenogenetically activated. The latter embryos should not be considered for embryo replacement.

Adult↗
PubMed1995

Enhancement of fertilization by micromanipulation.

Micromanipulation techniques have been successfully applied to human gametes to assist fertilization when normal function is impaired. The past few years have witnessed the rapid evolution and clinical incorporation of this technology. The unprecedented efficiency of intracytoplasmic sperm injection far surpasses all previous methods. This method has thus become the best treatment option for many forms of male infertility.

Adult↗
PubMed1995

Embryo morphology, developmental rates, and maternal age are correlated with chromosome abnormalities.

OBJECTIVE: To determine some of the unresolved questions related to chromosome anomalies in early human embryos, such are the detection of any advanced maternal age effect; the complete assessment of mosaicism, which requires analysis of all cells; and the relationship with embryonic dysmorphism. Fluorescence in situ hybridization has been used in this study to answer these issues. DESIGN: Fluorescence in situ hybridization analysis of human embryos using simultaneously probes for three or five chromosomes. Five hundred twenty-four cleavage-stage human embryos obtained by IVF were analyzed by fluorescence in situ hybridization. Embryos were allocated into three groups according to morphological and developmental characteristics (arrested; slow and/or fragmented; morphologically and developmentally normal). The embryos also were analyzed according to maternal age. RESULTS: Dysmorphic embryos had higher rates of polyploidy and diploid mosaicism. Aneuploidy increased with maternal age in nonarrested embryos. Preimplantation genetic diagnosis successfully detected these abnormalities. CONCLUSION: This study demonstrates that, in morphologically and developmentally normal human embryos, cleavage-stage aneuploidy significantly increases with maternal age. The results suggest that implantation failure in older women largely could be due to aneuploidy.

Adult↗
PubMed1994

Epididymal micropuncture with in vitro fertilization and oocyte micromanipulation for the treatment of unreconstructable obstructive azoospermia.

OBJECTIVE: To provide fertility to couples in whom the man has surgically unreconstructable obstructive azoospermia. DESIGN: Prospective. SETTING: Hospital-based IVF unit, including associated division of urologic microsurgery. PATIENTS: Couples referred to our fertility unit for treatment of men with surgically unreconstructable reproductive tract obstruction, including congenital absence of the vas deferens. MAIN OUTCOME MEASURES: Fertilization, pregnancies, and live births. RESULTS: Of 51 cycles in which sperm and eggs were retrieved, 67% (34/51) resulted in fertilization and 27.5% (14/51) developed clinical pregnancy. Clinical pregnancy rate per couple was 33% (14/43). A total of 15 live births have been obtained in 11 couples with one ongoing pregnancy. Epididymal length was the best predictor of sperm quality and pregnancy results. For couples with at least the corpus epididymis present, 41% (9/22) of cycles resulted in clinical pregnancies. CONCLUSIONS: Pregnancy rates are optimized using sperm retrieved from the epididymis by micropuncture and when micromanipulation is available for use during IVF.

Cell Survival↗
PubMed1994

Rescue of human embryos by micromanipulation.

This chapter evaluates clinical micromanipulation techniques aimed at rescuing abnormally developing zygotes and cleaved embryos. First, the possibility of reversing dispermic zygotes to a normal biparental diploid state was evaluated by extracting the distal pronucleus (that furthest from the polar body). The ratio of X:Y was determined in both groups of embryos by assessing a minimum of two blastomeres using duplex PCR or multiple colour FISH. The ratio of embryos containing only an X chromosome and those with X as well as Y chromosomes in the intact dispermic zygotes was 1.0:2.6, which is similar to the theoretical ratio of 1:3. This ratio was 1.0:1.5 in dispermic zygotes from which the distal pronuclei were removed. Although the ratio of X:Y was altered following removal of distal pronuclei, suggesting frequent targeting of male pronuclei, accidental removal of the female pronucleus could not be excluded. In a second set of mouse experiments, it was shown that the hatching process of embryos that develop with excessive amounts of degenerate material is adversely affected. It was shown that removal of such extracellular material by micromanipulation potentially reverted the hatching process. It was also indicated that immediate removal of the degenerate tissue was more beneficial than that following prolonged co-culture. Assisted hatching is probably the most frequently applied clinical embryo micromanipulation procedure. The outcome of assisted hatching is dependent largely on the mode by which the zona pellucida is breached, the size of the artificial gap and the thickness of the zona pellucida. Embryos with zonae thicker than 17 microns rarely implant. Zona drilling could be detrimental in embryos with thin zonae (< 12 microns). Superficial zona thinning has not enhanced implantation. These observations led to a routine procedure called selective assisted hatching, which involves measuring the zonae before zona drilling and replacement on day 3 of development. This appears to be most successful in older women and those with elevated basal FSH levels. Selective assisted hatching is routinely applied in consenting patients whose embryos have thick zonae, slow development or excessive fragmentation (> 20%). Zona drilling of all embryos, regardless of zona thickness, is being performed in patients aged over 40 years and in those with repeated failures or elevated basal FSH levels. Results in the first group of more than 900 patients indicate that nearly one-quarter of human embryos have the ability to implant.

Animals↗
PubMed1994

Monospermic polyploidy and atypical embryo morphology.

Monospermic cleavage-arrested human embryos were analysed by fluorescence in-situ hybridization using specific DNA probes for chromosomes X, Y and 18 simultaneously. Two groups of monospermic polyploid embryos could be distinguished: (i) embryos (n = 13) with only one large cell surrounded by smaller blastomere-sized extracellular fragments. These embryos were polyploid and frequently polyploid mosaic. (ii) Embryos developing from larger than normal oocytes were triploid or triploid mosaics (n = 4). Atypical morphology was not seen in eight other polyploid monospermic embryos. The atypical morphologies described here are quite rare, but are genetically uniform. Polyspermic embryos are the only other known example of a dual genetic-morphological abnormality.

Blastomeres↗
PubMed1994

Healthy deliveries from biopsied human embryos.

Preimplantation genetic diagnosis was performed in 122 embryos obtained by IVF from 11 patients carriers of haemophilia, Duchenne's muscular dystrophy, Barth's syndrome, cystic fibrosis, Pelizaeus-Merzbacher syndrome or Rett's syndrome. After multiplex polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH) analysis with multiple probes, 28 embryos diagnosed as not affected were replaced. Of these, eight implanted (28%) and produced three ongoing pregnancies, three deliveries of four babies and a biochemical pregnancy. However, one case screened for cystic fibrosis was misdiagnosed and the pregnancy was terminated. In order to evaluate the efficiency of multiplex PCR, 55 non-replaced embryos were reassessed by PCR or by FISH. Identical results were obtained in all cases. However, one embryo which had only X-chromosome specific amplification by PCR was found to be XO in all its cells by FISH. Although multiplex PCR is demonstrated to be reliable for sexing of human embryos, FISH has the additional advantages of supplying ploidy assessment while not being affected by contamination.

Biopsy↗
PubMed1994

Monozygotic twinning in the human is associated with the zona pellucida architecture.

Six cases of identical twin pregnancies which occurred in 2163 cycles of in-vitro fertilization during a 3 year period are reported. Monozygosity was confirmed when the number of fetuses exceeded the number of embryos replaced (n = 4) or when two concepti were observed in a single amniotic sac (n = 2). Each of the reported pregnancies resulted from replacement of embryos either with naturally thin zonae pellucidae or embryos whose zonae had been breached during micromanipulation for assisted fertilization (subzonal sperm insertion) or assisted hatching. That such cases exclusively gave rise to monozygosity suggests a link between the physical state of the zona pellucida, hatching, and generation of identical twins.

Blastocyst↗
PubMed1993

Plasmanate as a medium supplement for in vitro fertilization.

PURPOSE: The purpose of this study was to evaluate the use of Plasmanate, a protein preparation containing human serum albumin and mixed globulins to autologous preovulatory maternal serum, as an in vitro fertilization (IVF) medium supplement. Plasmanate was used most often in cases involving unexplained infertility, sperm antibodies, and endometriosis or when serum was unavailable. RESULTS: In a retrospective analysis of 1019 consecutive IVF cycles, Plasmanate was used as the protein supplement to the fertilization medium in 28.6% and maternal serum was used in 71.4% of the attempts. Attempting to eliminate the effects of different medium lots and laboratory conditions, 450 matched patient cycles were compared using the two protein supplements. Finally, the effects of Plasmanate versus maternal serum were compared in prospective randomized trial on patients diagnosed with tubal infertility who were attempting IVF for the first time. The clinical pregnancy rate was 34% for the Plasmanate group versus 24% for those using maternal serum in the retrospective investigation. However, this trend was reversed in the prospective trial. CONCLUSION: Although further investigation is necessary, it appears that Plasmanate is an appropriate protein substitute in patient cases where serum is absent or unsuitable.

Adult↗
PubMed1993

Microsurgical correction of partially degenerate mouse embryos promotes hatching and restores their viability.

We have evaluated the effects of degeneration of blastomeres on the developmental fate of mouse embryos. Micromanipulation techniques were used first to destroy one or two blastomeres of a 4-cell embryo (thereby creating three-quarter and half embryos), and later to repair the anomaly by removing the degenerate material. The embryos were either cultured in protein-free or protein-supplemented medium. When cultured in protein-supplemented medium, three-quarter embryos hatched at the same rate as intact embryos (84 and 91%, respectively), but this rate was reduced (54%; 67/125) when the embryos were cultured in a protein-free environment. Destruction of two blastomeres of a 4-cell embryo and culture in protein-free medium was detrimental, as only 3.2% (4/124) hatched. By supplementing the culture medium with protein, some of these half embryos were rescued, as shown by a 34% (32/95) hatching rate. A more dramatic increase in hatching was achieved, however, after repair of the half embryos by microsurgical removal of the degenerate material. In this case, 72% (78/109) of the repaired embryos were able to hatch. These findings may have implications for human in-vitro fertilization where partial embryonic degeneration or fragmentation often leads to embryonic demise and reduced implantation. Moreover, these observations may provide important clues to mechanisms of mammalian embryonic hatching.

Animals↗
PubMed1993

Opening of the mouse zona pellucida by laser without a micromanipulator.

A contact-free laser system is described for ablation of the embryonic mouse zona pellucida using a pulsed excimer 308 nm laser. Effects on further embryonic development were evaluated. Zonae of 8- to 16-cell mouse embryos were either lased (n = 189), zona-drilled with acidified Tyrode's solution (n = 183) or left zona-intact (n = 188). Blastocyst formation (99-100%) was similar in the three groups. Hatching occurred earlier in lased embryos compared to those of the control group. These blastocysts hatched through the laser ablated area. Significantly more embryos were hatching on day 4 in the conventionally drilled group when compared to the laser treated group (50% versus 24% respectively). On day 7 of development, significantly (P < 0.05) more embryos conventionally zona-drilled (37%) were intact than those which were previously laser treated (10%). Abnormal development was also noted in a small group of embryos which were lased just on the outside of the zona in comparison to 1/3 of an embryonic width away from the zona. The current results suggest that apparently precise zona laser ablation with an excimer laser at 308 nm may have potential adverse effects which may only be manifested after a prolonged period of culture past the cavitation stage. However, implantation rates of morphologically normal laser abalated embryos were not impaired when compared to control embryos.

Animals↗
PubMed1993

Assisted hatching facilitates earlier implantation.

OBJECTIVE: To examine whether opening of the zona pellucida (i.e., assisted hatching) accelerates implantation. DESIGN: In a controlled, randomized trial, patients were assigned to control and assisted hatching groups. SETTING: All patients studied were of the Center for Reproductive Medicine at Cornell University Medical College. INTERVENTION: All patients underwent stimulation with gonadotropins after luteal phase GnRH down regulation. Assisted hatching with zona drilling using acidic Tyrode's solution was performed on the assigned embryos. MAIN OUTCOME MEASURES: Luteal E2, P, and hCG on days +5, +6, +7, +8, +9, +11, +13, and +15 were measured. The implantation time, peak midluteal E2 and intervals between these two values were studied. RESULTS: Implantation occurred significantly earlier in the assisted hatching group. The interval between implantation and peak midluteal E2 was also significantly shorter in the assisted hatching group than in the controls. However, there was no significant difference in the day of the peak midluteal E2 between the assisted hatching and control groups. CONCLUSION: Assisted hatching may enhance embryo implantation not only by mechanically facilitating the hatching process but also by allowing earlier embryo-endometrium contact. Such early contact may enhance embryonic development potential and may optimize synchronization between embryo and endometrium, resulting in improved implantation efficiency.

Chorionic Gonadotropin↗
PubMed1993

Micromanipulation of human gametes for assisted fertilization.

The techniques of partial zona dissection, subzonal sperm insertion, and intracytoplasmic sperm injection have been clinically employed to alleviate aberrations of human gamete interaction. This article reviews the current status of assisted fertilization technology and its relevance in treating male infertility. Indications for the application of each technique and factors affecting outcome are discussed.

Dissection↗
PubMed1992

Micromanipulation of cleaved embryos cultured in protein-free medium: a mouse model for assisted hatching.

A mouse model for studying anomalies of human embryonic hatching following micromanipulation is proposed. Initiation and completion of mouse blastocyst hatching was severely impaired (34/292; 12% and 28/292; 10%, respectively) with protein deprivation, resembling the situation in human in vitro fertilization. Hatching ability was restored when an artificial gap was introduced in the zona pellucida by micromanipulation at the cleaved embryo stage. This enabled 77% (285/371) and 36% (134/371) of the embryos to initiate and complete hatching in protein-free medium. No differences were found in overall cell counts between the two groups of embryos. Transfer of micromanipulated blastocysts to pseudopregnant females resulted in development of healthy fetuses.

Animals↗
PubMed1992

Subzonal sperm insertion and the frequency of gamete fusion.

The subzonal sperm insertion technique was applied to assess the potential of motile human spermatozoa to form pronuclei. In 184 mature human oocytes, subzonal sperm insertion was used as the primary mode of insemination in cases with abnormal semen analyses. Oocytes (n = 131) that failed to fertilize in vitro in cases with normal semen profiles were also micromanipulated for secondary insemination. The frequency of sperm fusion, expressed as a percentage, was defined as the total number of male pronuclei formed divided by the total number of spermatozoa inserted subzonally. Our results indicate that 37% of spermatozoa from men with normal semen are able to fuse with the oolemma and decondense within the ooplasm, when placed in the perivitelline space of the oocyte. Excluding the oocytes that appeared morphologically abnormal (presence of cytoplasmic inclusions such as refractile bodies within the ooplasm), the frequency of sperm fusion increased to nearly 60%. Moreover, 14% of subzonally inserted spermatozoa from men with abnormal semen analyses demonstrated an ability to form a pronucleus. The incidence of polyspermy was high, ranging from 30 to 80% in the different groups studied. It is therefore concluded that the human oolemma provides little protection against multiple sperm fusion and that the frequency of gamete fusion is unexpectedly high, even when the spermatozoa are derived from infertile men.

Evaluation Studies as Topic↗
PubMed1992

Microsurgical fertilization procedures: the absence of stringent criteria for patient selection.

Subzonal sperm insertion and partial zona dissection were applied in 250 in vitro fertilization cycles in couples (n = 200) with abnormal semen analyses; 61 clinical pregnancies were established (24% per egg retrieval). Patients were selected without using minimal cutoff criteria. The study included patients with 0% normal sperm forms (strict criteria), no motile sperm (but some live cells), and sperm counts which could be assessed only after centrifugation. Patients were categorized into three subsets. Group A (n = 116 cycles) failed to fertilize in a previous cycle. Group B (n = 40) was excluded from IVF due to the severity of sperm profiles, such as a maximum of 2% normal forms. Group C (n = 94) constitutes those patients for whom a standard cycle could possibly result in failure. Monospermic fertilization rates were 18% (A), 19% (B), and 24% (C). The incidences of embryo replacement were 63% (A), 53% (B), and 69% (C). Rates of clinical pregnancy were 22% (A), 23% (B), and 28% (C). The presence of one, two, or three semen abnormalities did not correlate with the outcome of microsurgical fertilization. Twenty-two percent of patients with combined oligoasthenoteratozoospermia became pregnant. Moreover, ongoing pregnancies were established in instances with 0% normal sperm forms and no progressively motile spermatozoa. It is concluded that stringent cutoff criteria may not be necessary when both partial zona dissection and subzonal sperm insertion are performed efficiently.

Culture Techniques↗