Author
Lani J. Burkman
Other affiliations: Tygerberg Hospital, Life Technologies
Bio: Lani J. Burkman is an academic researcher from Eastern Virginia Medical School. The author has contributed to research in topics: Sperm & Zona pellucida. The author has an hindex of 15, co-authored 15 publications receiving 1348 citations. Previous affiliations of Lani J. Burkman include Tygerberg Hospital & Life Technologies.
Papers
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TL;DR: Sperm from fertile men exhibited significantly higher binding capacity to hemizonae compared with sperm from men who had fertilization failure during in vitro fertilization (IVF) treatment, demonstrating that the HZA may be a useful diagnostic tool in male infertility evaluations.
390 citations
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TL;DR: New criteria for automatic sorting of all HA patterns that are consistent with the classical descriptions are defined and the incidence of HA is significantly associated with multiple fertilization endpoints.
160 citations
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TL;DR: Assessment of the relationship between sperm binding to the hemizona and in vitro fertilization (IVF) success enhanced confidence that the HZA is diagnostic for identification of patients at high risk of failing to achieve fertilization in vitro.
Abstract: The hemizona assay (HZA) was developed to assess human sperm fertilizing potential. This blinded study investigated the relationship between sperm binding to the hemizona and in vitro fertilization (IVF) success (36 patients). Nonliving human oocytes were recovered from excised ovaries and stored. Each zona pellucida was cut into equal hemispheres by micromanipulation. For the HZA, one droplet exposed a hemizona to abnormal spermatozoa, while the control droplet contained the matching hemizona and spermatozoa from normal semen. After 4 hr, the number of tightly bound spermatozoa was counted. Binding to the hemizona was significantly higher for those having IVF success (mean of 36.1±7, versus 10.4±4 from the failure group;P<0.05). Fewer sperm from the failure group had a strictly normal morphology (3,2 versus 12.7%;P<0.05, Kruger method). Tight zona binding was significantly correlated with the percentage motile sperm, percentage normal morphology, and seminal sperm concentration. These results enhanced our confidence that the HZA is diagnostic for identification of patients at high risk of failing to achieve fertilization in vitro.
124 citations
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TL;DR: The authors conclude that the HZA is a valuable tool for evaluating dysfunctional sperm-zona pellucida binding, with good predictive value for fertilization in vitro.
117 citations
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TL;DR: Salt storage offers a simple and inexpensive means for accumulating and transporting human zonae pellucida; the resulting hemizonae function effectively in the new hemizona assay (HZA) for estimating sperm binding potential.
Abstract: Human oocytes were stored (25 degrees C) in 1.5 M MgCl2 for 6-30 days, then utilized in the new hemizona assay (HZA) for tight binding of human spermatozoa [Burkman et al.: Fertil Steril 49:688-697, 1988]. We have compared 1) the ability of matching salt-treated hemizonae or dimethylsulfoxide (DMSO)-treated hemizonae to distinguish between sperm from semen having normal versus subnormal characteristics and, 2) the kinetics of fertile sperm binding to salt-treated or DMSO-treated hemizonae. After sperm preparation one salt-treated hemizona was incubated with normal spermatozoa and the matching hemizona was placed with sperm from the subnormal group. As a control, DMSO-treated hemizonae were incubated in additional sperm droplets. After 4 hours, the number of sperm tightly bound to each hemizona was counted. Within the normal semen group, there was equivalent binding to salt- or DMSO-treated hemizonae (54.0 +/- 12 and 49 +/- 14, respectively, mean +/- SEM). Similarly, tight binding of sperm from the subnormal group was not affected by the zona storage method (21 +/- 8 and 17 +/- 5, respectively). For either storage approach, binding of subnormal sperm was significantly less (P less than 0.01) compared with the number of normal sperm attached to the matching hemizona. For the kinetics study, the hemizona binding of proven fertile spermatozoa was followed throughout 8.5 hours. The shape of the binding curve was the same for zonae stored by either method and was consistent with our published kinetics data. Salt storage offers a simple and inexpensive means for accumulating and transporting human zonae pellucida; the resulting hemizonae function effectively in the HZA for estimating sperm binding potential.
83 citations
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01 Jan 2010
2,199 citations
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TL;DR: Although some interesting results, mainly in humans, have already been obtained, many questions remain, which have to be answered to allow for further development of this technology in veterinary medicine, clinical fertility settings, physiological and toxicology research activities.
655 citations
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TL;DR: Computer-assisted semen analysis systems can be used to identify hyperactivated sperm by setting minimum thresholds for curvilinear velocity and lateral head movement and a maximum threshold for path linearity, which could enable clinicians to develop reliable fertility assays to assess normal hyperactivation in human sperm samples.
Abstract: BACKGROUND: Sperm hyperactivation is critical to fertilization, because it is required for penetration of the zona pellucida. Hyperactivation may also facilitate release of sperm from the oviductal storage reservoir and may propel sperm through mucus in the oviductal lumen and the matrix of the cumulus oophorus. Hyperactivation is characterized by high amplitude, asymmetrical flagellar bending. METHODS: This is a review of the original literature on the mechanisms that regulate hyperactivation, including physiological factors and signaling pathways. RESULTS: Computer-assisted semen analysis systems can be used to identify hyperactivated sperm by setting minimum thresholds for curvilinear velocity (VSL) and lateral head movement and a maximum threshold for path linearity. Hyperactivation is triggered by a rise in flagellar Ca(2+) resulting from influx primarily through plasma membrane CatSper channels and possibly also by release of Ca(2+) from a store in the redundant nuclear envelope. It requires increased pH and ATP production. The physiological signals that trigger the rise in Ca(2+) remain elusive, but there is evidence that the increased Ca(2+) acts through a calmodulin/calmodulin kinase pathway. Hyperactivation is considered part of the capacitation process; however, the regulatory pathway that triggers hyperactivation can operate independently from that which prepares sperm to undergo the acrosome reaction. Hyperactivation may be modulated by chemotactic signals to turn sperm toward the oocyte. CONCLUSIONS: Little is known about exactly what triggers hyperactivation in human sperm. This information could enable clinicians to develop reliable fertility assays to assess normal hyperactivation in human sperm samples.
505 citations
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TL;DR: Spermatozoa from infertile men display translocation of membrane phosphatidylserine as diagnosed by annexin V positive staining, and there is a relationship between DNA damage and oxidative stress.
Abstract: UNLABELLED The objectives of this cross-sectional observational study were: (i) to detect DNA damage and plasma membrane translocation of phosphatidylserine in purified sperm populations of high and low motility, and (ii) to analyse their relationship with the endogenous generation of reactive oxygen species. Ejaculates from infertile men were examined following gradient centrifugation. The main outcome measures were: sperm motion parameters (assessed with a computer analyser), generation of reactive oxygen species (measured by chemiluminescence), DNA damage (detected by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling and monoclonal antibody labelling of single-stranded DNA) and translocation of membrane phosphatidylserine (examined with annexin V staining). DNA fragmentation and membrane translocation of phosphatidyl-serine were observed in the fractions with low and high sperm motility in all patients. The fractions with low sperm motility had significantly higher proportion of cells with DNA damage and production of reactive oxygen species than the fractions with high sperm motility (P < 0.005). DNA fragmentation was significantly and positively correlated with the generation of reactive oxygen species (r = 0.42; P = 0.02). IN CONCLUSION (i) spermatozoa from infertile men display translocation of membrane phosphatidylserine as diagnosed by annexin V positive staining; (ii) DNA damage (fragmentation and presence of single-stranded DNA) can be detected in ejaculated spermatozoa from infertile men in fractions with low and high sperm motility, and (iii) there is a relationship between DNA damage and oxidative stress.
475 citations
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TL;DR: The data clearly demonstrate that DNA fragmentation, as determined by the TUNEL assay, is predictive for pregnancy in IVF, which implies that spermatozoa with DNA fragmentation can still fertilize an oocyte but that when paternal genes are "switched on," further embryonic development stops, resulting in failed pregnancy.
380 citations