New perspectives on the role of hyperglycemia, free fatty acid and oxidative stress in beta-cell apoptosis

Apoptosis is a complex network of biochemical and molecular pathway with fine regulatory mechanisms that control the death event .during several pathological situations in multi cellular organisms. It is the part of normal development that occurs in a variety of diseases and is known as aberrant apoptosis. Pancreatic cell apoptosis is also a pathological feature which is common in both type 1 and type 2diabetes. There are several reasons through which apoptosis can be induced in p-cell. Metabolic abnormalities such as hyperlipidemia and hyperglycemia have been cited as critical mediator of cell death and may either trigger p-cell apoptosis. Persistent hyperglycemia causes increased production of free radicals that can damage initial P-cell in type I diabetes, impaired insulin production, release or function in type II diabetes. Also apoptosis plays an important role in several diabetic complications. The role of metabolic factors and their mechanism in P-cell apoptosis have been surveyed in this paper

Tyrosine phosphorylation pattern in sperm proteins isolated from normospermic and teratospermic men

In mammalian system, spermatozoa are not able to fertilize the oocyte immediately upon ejaculation, thus they undergo a series of biochemical and molecular changes which is termed capacitation. During sperm capacitation, signal transduction pathways are activated which lead to protein tyrosine phosphorylation. Tyrosine phosphorylated proteins have an important role in sperm capacitation such as hyperactive motility, interaction with zona pellucida and acrosome reaction. Evaluation of tyrosine phosphorylation pattern is important for further understanding of molecular mechanisms of fertilization and the etiology of sperm dysfunctions and abnormalities such as teratospermia. The goal of this study is to characterize tyrosine phosphorylation pattern in sperm proteins isolated from normospermic and teratospermic infertile men attending Avicenna Infertility Clinic in Tehran. Semen samples were collected and the spermatozoa were isolated using Percoll gradient centrifugation. Then the C with 5% CO[2] in 3% Bovine Serum spermatozoa were incubated up to 6h at 37 Albumin-supplemented Ham's F-10 for capacitation to take place. The total proteins from spermatozoa were extracted and were subjected to SDS-PAGE before and after capacitation. To evaluate protein tyrosine phosphorylation pattern, western blotting with specific antibody against phosphorylated tyrosines was performed. The results upon western blotting showed: 1] at least six protein bands were detected before capacitation in the spermatozoa from normospermic samples. However, comparable levels of tyrosine phosphorylation was not observed in the spermatozoa from teratospermic samples. 2] The intensity of protein tyrosine phosphorylation appears to have been increased during capacitation in the normospermic relative to the teratospermic group. For the first time, these findings demonstrate and suggest that the differences in the types of proteins and diminished tyrosine phosphorylation efficiency in sperm from teratospermic men may be responsible for their compromised capacitation and low fertilization success rates

Nutrigenomics and Cancer

Cancer incidence is projected to increase in the future and an effectual preventive strategy is required to face this challenge. Alteration of dietary habits is potentially an effective approach for reducing cancer risk. Assessment of biological effects of a specific food or bioactive component that is linked to cancer and prediction of individual susceptibility as a function of nutrient-nutrient interactions and genetics is an essential element to evaluate the beneficiaries of dietary interventions. In general the use of biomarkers to evaluate individuals susceptibilities to cancer must be easily accessible and reliable. However, the response of individuals to bioactive food components depends not only on the effective concentration of the bioactive food components, but also on the target tissues. This fact makes the response of individuals to food components vary from one individual to another. Nutrigenomics focuses on the understanding of interactions between genes and diet in an individual and how the response to bioactive food components is influenced by an individual's genes. Nutrients have shown to affect gene expression and to induce changes in DNA and protein molecules. Nutrigenomic approaches provide an opportunity to study how gene expression is regulated by nutrients and how nutrition affects gene variations and epigenetic events. Finding the components involved in interactions between genes and diet in an individual can potentially help identify target molecules important in preventing and/or reducing the symptoms of cancer