Biomedical subjects
Publications and source records attributed to Suresh Sikka.
We analyzed the testicular spermatozoa of 23 infertile men after cryopreservation to evaluate their cryosurvival and to scrutinize the effectiveness of freezing protocol used in our institution. An excellent postthaw motility was observed indicating an effective cryosurvival protocol.
PURPOSE OF REVIEW: This review summarizes the role of free radicals and oxidative stress in the pathophysiology of human reproduction. RECENT FINDINGS: An extensive review of the literature on the role of oxidative stress in influencing assisted reproduction and its outcome is described in this article. Free radicals or reactive oxygen species mediate their action through many of the proinflammatory cytokines and this mechanism has been proposed as a common underlying factor for endometriosis, ovarian cancer, polycystic ovary disease, and various other pathologies affecting the female reproductive process, as highlighted in this review. Oxidative stress, sperm DNA damage, and apoptosis have been implicated in male infertility. Elevated reactive oxygen species levels correlate with the poor fertility outcomes seen in the assisted reproductive technology setting. SUMMARY: Oxidative stress has been implicated in male and female infertility, including fetal dysmorphogenesis, abortions, and intrauterine growth restriction. Accurate evaluation of seminal oxidative stress by standardized assays may help in the diagnosis and management of male infertility. There is evidence in the literature on the beneficial effects of oral antioxidant supplementation in male infertility. Current ongoing trials will provide answers on the safety and effectiveness of antioxidants in improving maternal and fetal outcomes. Further studies need to be conducted to determine if antioxidant supplementation will prevent fetal developmental defects in high-risk pregnancy with diabetes.
Hypermethylation at certain CpG-rich promoters and hypomethylation at repeated DNA sequences are very frequently found in cancers. We provide the first report that a DNA sequence (NBL2) can be either extensively hypermethylated or hypomethylated in cancer. Previously, it was shown that NBL2, a complex tandem DNA repeat in the acrocentric chromosomes, is hypomethylated at NotI sites in >70% of neuroblastomas and hepatocellular carcinomas and in cells from ICF syndrome (DNMT3B-deficiency) patients. Unexpectedly, by Southern blot analysis of 18 ovarian carcinomas, 51 Wilms tumors, and various somatic control tissues, we found that >70% of the cancers exhibited large increases in methylation at HhaI sites in NBL2 compared with all the controls. In contrast, 17% of the carcinomas showed major decreases in methylation at HhaI and NotI sites. The intermediate levels of methylation at HhaI sites in somatic controls enabled this discovery of cancer-linked hypermethylation and hypomethylation in NBL2. In a comparison of ovarian epithelial carcinomas, low malignant potential tumors, and cystadenomas, NBL2 hypermethylation at HhaI sites was significantly related to the degree of malignancy, and hypomethylation was seen only in the carcinomas. By RT-PCR, we found NBL2 transcripts at low levels in a few cancers and undetectable in various normal tissues. In the tumors there was no association of NBL2 hypomethylation and transcription, but this may reflect NBL2's lack of identifiable promoter elements and our evidence for run-through transcription from adjacent sequences into NBL2. The propensity of NBL2 sequences to become either hypermethylated or hypomethylated in cancer suggests that these opposite epigenetic changes share an early step during carcinogenesis and that cancer-linked hypermethylation might be spontaneously reversible.
BACKGROUND AND PURPOSE: As laparoscopic surgery has evolved, it has become part of the urologic surgical armamentarium and is now used to perform more complex procedures. Carbon dioxide, used to create pneumoperitoneum, produces physiologic changes in various organs, including the kidneys. Such changes are associated with altered redox status because of the release of free radicals and changes in oxidative stress signals. It is unknown whether prolonged pneumoperitoneum is associated with an increase in oxidative stress compared with open surgery. The objective of this study was to compare oxidative stress in patients undergoing urologic laparoscopic and open operations. PATIENTS AND METHODS: Urine samples were obtained immediately preoperatively, immediately postoperatively, and at 6 and 18 hours after surgery from 10 patients who underwent urologic laparoscopic surgery and 10 patients who underwent open surgery. Concentrations of the oxidative stress marker isoprostane (8- iso-prostaglandin F2a) were measured, and the results were analyzed with respect to clinical factors associated with the type of surgery. RESULTS: Urinary isoprostane concentrations (mean +/- SEM) in the laparoscopic and open groups showed an increase immediately after surgery to 189.0 +/- 64.2% and 141.1 +/- 45.8% of the preoperative values, respectively. A decrease in isoprostane was subsequently observed in both groups at 6 hours postoperatively, with preoperative values restored at 18 hours postoperatively (126.3 +/- 19.7% and 89.5 +/- 55.9% at 6 and 18 hours, respectively, in the laparoscopic group and 130.7 +/- 41.6% and 88.7 +/- 20.4% at 6 and 18 hours, respectively, in the open-surgery group). Although in both groups the peak PGF 2a concentration was observed immediately (0 hours) postoperatively, no significant differences were observed between the groups at 0, 6, and 18 hours. In the laparoscopic-surgery group, the mean increase tended to be higher and the decrease to be less prolonged than in the open-surgery group. CONCLUSION: Oxidative stress, as measured by urinary 8-iso-prostaglandin F2a, is produced by both laparoscopic and open urologic surgery. The findings of our nonrandomized study suggest a pattern of increased oxidative stress postoperatively with either type of surgery, with subsequent return almost to preoperative levels. Prolonged laparoscopic operative time did not affect oxidative stress levels.
BACKGROUND: Intralesional therapies provide an alternative to surgical treatment of Peyronie's disease (PD). This study examines the efficacy of intraplaque injections of interferon-alpha-2B (IFN-alpha-2B) in the treatment of PD. METHODS: Twenty-five patients were enrolled in the study with 21 completing the study. The average age of the study participants was 55.8 years, with 10 of the 21 having diabetes, hypertension, or both. Seven patients received placebo injections using 10 ml saline biweekly for 6 weeks before interferon therapy, and all 21 patients received biweekly injections of 2 x 10(6) U IFN-alpha-2B for 6 weeks before reevaluation. Patients were evaluated with duplex Doppler ultrasonography to assess penile curvature and blood flow. RESULTS: The International Index of Erectile Function questionnaire was completed by 14 of 21 men to assess severity of erectile dysfunction (ED) before and after treatment. Improvements of 20% or more in penile curvature occurred in 14 (67%) of 21 men. Penile pain decreased in eight (80%) of 10, and plaque size decreased subjectively in 15 (71%) of 21 participants. The International Index of Erectile Function questionnaire showed significant improvement of ED in five (71%) of seven men with baseline moderate to severe ED. Peak systolic blood flow improved in three (43%) of seven men with baseline hemodynamic impairment, and veno-occlusive disease resolved in three (18%) of 17 individuals. IFN-alpha-2B injections led to significant improvements in penile pain and curvature caused by PD. CONCLUSION: Results of intralesional IFN-alpha-2B injections in improving ED are encouraging. The study findings warrant further investigation of the effectiveness of IFN-alpha-2B injections for treatment of PD.
Acquirement of multi-drug resistance by tumor cells represents a major obstacle in the management of prostate cancer. Such resistance was demonstrated in the androgen-independent DU-145 cells in response to paclitaxel and the mechanisms by which these cell develops resistance was not understood. The objective of this study was to examine whether abrogation of the constitutively active NF-kappaB in the chemoresistant, androgen independent DU-145 prostate cancer cells will enhance their sensitivity to cytototoxic agents. Inhibition of NF-kappaB by a dominant negative super-repressor IkappaB mutant adenoviral construct enhanced the apoptotic potentials of paclitaxel and rhTNF-alpha in these cells. Using reporter assays and RT-PCR analysis, we demonstrate that paclitaxel-induced cell death was associated with an increase in NF-kappaB activation and MDR-1 gene expression. Abrogation of these effects by the dominant negative IkappaB adenoviral construct suggests that induction and/or constitutive activation of NF-kappaB can block the paclitaxel-induced apoptotic signaling pathways in this cell line, possibly by increasing the expression of anti-apoptotic and MDR-1 gene products, leading to development of chemoresistance in these cells. We conclude that inhibition of NF-kappaB activation may have therapeutic implications for prostate cancer.
The mechanism of reactive oxygen species (ROS) generation in human sperm has recently been found to depend upon a novel NADPH-oxidase (NOX5) resembling the multicomponent NADPH-oxidase of white blood cells (WBCs). The purpose of our study was to compare the ROS producing activity of NOX5 in sperm and NADPH-oxidase of WBCs, and to investigate the role of protein kinase C (PKC) in NOX5 activation. A combination of electron paramagnetic resonance (EPR), chemiluminescence (CL), and nitroblue tetrazolium (NBT) dye reduction were used to monitor ROS production by sperm. The involvement of PKC in NOX5 activation was investigated using myristate acetate (PMA), and the PKC inhibitor GF-109203X. The presence of b cytochrome in NOX5 was investigated by spectrophotometry. PMA-stimulated WBCs produced superoxide dismutase -- inhibitable EPR signals for both superoxide and hydroxyl radicals. Sperm did not produce these spectra with or without PMA stimulation. WBCs generated significantly increased levels of CL and reduced NBT after PMA stimulation; whereas sperm did not increase the CL response or reduce NBT. Adenosine triphosphate (ATP) levels in WBCs were significantly reduced after PMA stimulation, whereas sperm ATP levels did not change. The characteristic spectra of b cytochrome observed after dithionite reduction of WBCs was not observed with sperm under similar conditions. These results indicate that the ROS producing activity of NOX5 is significantly lower than the WBC NADPH-oxidase, and suggest that the activation mechanism of NOX5 in sperm is independent of PKC.