Micro-Raman and Spreading Resistance Analysis on Beveled Implanted Germanium for Layer Transfer Applications

Raman and spreading resistance profiling have been used to analyze defects in germanium caused by hydrogen and helium implants, of typical fluences used in layer transfer applications. Beveling has been used to facilitate probing beyond the laser penetration depth. Results of Raman mapping along the projection area reveal that after post-implant annealing at 400°C, some crystal damage remains, while at 600°C, the crystal damage has been repaired. Helium implants create acceptor states beyond the projected range, and for both hydrogen and helium, 1×1016 acceptors/cm2 remain after 600°C. These are thought to be vacancy-related point defect clusters.

Effect of phytoestrogen and antioxidant supplementation on oxidative DNA damage assessed using the comet assay

Antioxidant species may act in vivo to decrease oxidative damage to DNA, protein and lipids thus reducing the risk of coronary heart disease and cancer. Phytoestrogens are plant compounds which are a major component of traditional Asian diets and which may be protective against certain hormone-dependent cancers (breast and prostate) and against coronary heart disease. They may also be able to function as antioxidants, scavenging potentially harmful free radicals. In this study, the effects of the isoflavonoids (a class of phytoestrogen) genistein and equol on hydrogen peroxide-mediated DNA damage in human lymphocytes were determined using alkaline single-cell gel electrophoresis (the comet assay). Treatment with hydrogen peroxide significantly increased the levels of DNA strand breaks. Pre-treatment of the cells with both genistein and equol offered protection against this damage at concentrations within the physiological range. This protection was greater than that offered by addition of the known antioxidant vitamins ascorbic acid and alpha -tocopherol, or the compounds 17 beta -oestradiol and Tamoxifen which have similar structures to isoflavonoids and are known to have weak antioxidant properties. These findings are consistent with the hypothesis that phytoestrogens can, under certain conditions, function as antioxidants and protect against oxidatively-induced DNA damage. (C) 2001 Elsevier Science B.V. All rights reserved.

In vitro isoflavone supplementation reduces hydrogen peroxide-induced DNA damage in sperm

Isoflavones are plant compounds, proposed to have health benefits in a variety of human diseases, including coronary heart disease and endocrine-responsive cancers. Their physiological effects include possible antioxidant activity, therefore suggesting a role for isoflavones in the prevention of male infertility. The aim of this study was to test the antioxidant effects of the isoflavones genistein and equol on sperm DNA integrity, assessed in vitro after hydrogen peroxide-mediated damage, using the cornet assay. Pre-treatment with genistein or equol at doses of 0.01-100 mumol/l significantly protected sperm DNA against oxidative damage. Both ascorbic acid (10-600 mumol/l) and alpha-tocopherol (1-100 mumol/l) also protected. Compared with ascorbic acid and alpha-tocopherol, added at physiological concentrations, genistein was the most potent antioxidant, followed by equol, ascorbic acid, and alpha-tocopherol. Genistein and equol added in combination were more protective than when added singly. Based on these preliminary data, which are similar to those observed previously in lymphocytes, these compounds may have a role to play in antioxidant protection against male infertility.

Sperm DNA damage measured by the alkaline Comet assay as an independent predictor of male infertility and in vitro fertilization success

Objective: To evaluate sperm DNA fragmentation and semen parameters to diagnose male factor infertility and predict pregnancy after IVF.
Design: Prospective study.
Setting: Academic research laboratory.
Patient(s): Seventy-five couples undergoing IVF and 28 fertile donors.
Intervention(s): Sperm DNA fragmentation was measured by the alkaline Comet assay in semen and sperm after density gradient centrifugation (DGC). Binary logistic regression was used to analyze odds ratios (OR) and relative risks (RR) for IVF outcomes.
Main Outcome Measure(s): Semen parameters and sperm DNA fragmentation in semen and DGC sperm compared with fertilization rates, embryo quality, and pregnancy.
Result(s): Men with sperm DNA fragmentation at more than a diagnostic threshold of 25% had a high risk of infertility (OR: 117.33, 95% confidence interval [CI]: 12.72–2,731.84, RR: 8.75). Fertilization rates and embryo quality decreased as sperm DNA fragmentation increased in semen and DGC sperm. The risk of failure to achieve a pregnancy increased when sperm DNA fragmentation exceeded a prognostic threshold value of 52% for semen (OR: 76.00, CI: 8.69–1,714.44, RR: 4.75) and 42% for DGC sperm (OR: 24.18, CI: 2.89–522.34, RR: 2.16).
Conclusion(s): Sperm DNA testing by the alkaline Comet assay is useful for both diagnosis of male factor infertility and prediction of IVF outcome.

Cofilin immunolabelling correlates with depth of invasion in gastrointestinal endocrine cell tumors

Gastrointestinal endocrine cell tumors are a heterogeneous population of lesions believed to arise from neuroendocrine cells of the gastrointestinal mucosa. The current classification of these tumors is based on tumor size, microscopic features and clinical evidence of metastasis. Although diagnostic categories generally correlate with prognosis, molecular prognostic markers will be clinically useful adjuncts. Cofilin has been implicated in tumor invasion, and its immunolocalisation was studied in gastrointestinal endocrine cell tumors. The immunolocalisation of cofilin was studied by immunohistochemistry in 34 formalin-fixed, paraffin wax-embedded gastrointestinal endocrine cell tumors using a tissue microarray platform. A significant correlation was found between high cofilin immunolabelling and the depth of invasion (p

Relationships between human sperm protamines, DNA damage and assisted reproduction outcomes

The exchange of histones with protamines in sperm DNA results in sperm chromatin compaction and protection. Variations in sperm protamine expression are associated with male infertility. The aim of this study was to investigate relationships between DNA fragmentation, sperm protamines and assisted reproduction treatment. Semen and spermatozoa prepared by density-gradient centrifugation (DGC) from 73 men undergoing IVF and 24 men undergoing intracytoplasmic sperm injection (ICSI) were included in the study. Nuclear DNA fragmentation was assessed using the alkaline Comet assay and protamines were separated by acid-urea polyacrylamide gels. Sperm DNA fragmentation and protamine content (P1-DNA, P2-DNA, P1 + P2-DNA) decreased in spermatozoa after DGC. Abnormally high and low P1/P2 ratios were associated with increased sperm DNA fragmentation. Couples with idiopathic infertility had abnormally high P1/P2 ratios. Fertilization rates and embryo quality decreased as sperm DNA fragmentation or protamines increased. Sperm DNA fragmentation was lower in couples achieving pregnancies after IVF, but not after ICSI. There was no correlation between protamine content (P1-DNA, P2-DNA, P1 + P2-DNA) or P1/P2 ratios and IVF or ICSI pregnancies. Increased sperm DNA fragmentation was associated with abnormal protamination and resulted in lower fertilization rates, poorer embryo quality and reduced pregnancy rates. During late spermatogenesis, around 85% of the histones in the sperm nucleus are replaced with protamines. This process results in sperm chromatin compaction and also transcription silencing. In the human, protamines are comprised of two types: protamine-1 (P1) and protamine-2 (P2). Variations in sperm protamine expression are associated with male infertility. Similarly, sperm DNA integrity is important for male fertility. The aim of this study was to investigate relationships between DNA fragmentation, sperm protamines and assisted reproduction treatment. Semen and spermatozoa prepared by density-gradient centrifugation (DGC) from 73 men undergoing IVF and 24 men undergoing intracytoplasmic sperm injection (ICSI) were included in the study. Nuclear DNA fragmentation was assessed using the alkaline Comet assay and protamines were separated by acid-urea polyacrylamide gels. Sperm DNA fragmentation and protamine content decreased in spermatozoa after DGC. Abnormally high and low P1/P2 ratios were associated with increased sperm DNA fragmentation. Couples with idiopathic infertility had abnormally high P1/P2 ratios. Fertilization rates and embryo quality decreased as sperm DNA fragmentation or protamines increased. Sperm DNA fragmentation was lower in couples achieving pregnancies after IVF, but not after ICSI. There was no correlation between protamine content or P1/P2 ratios and IVF or ICSI pregnancies. Increased sperm DNA fragmentation was associated with abnormal protamination and resulted in lower fertilization rates, poorer embryo quality and reduced pregnancy rates.