Paraoxonases (PONs) i.e. PON1, PON2, PON3 are basically lactonases. Of these, PON1 in addition has an efficient esterase activity and can hydrolyze organophosphates. The PONs prevent low density lipoprotein cholesterol (LDL-C) from peroxidation, thereby preventing atherosclerosis. The PON1 is exclusively associated with high density lipoprotein cholesterol (HDL-C) and its antioxidant activity is largely attributed to PON1 located on it. At present, PON1 status i.e. its activity and concentration, is considered to be more important than polymorphism alone, in prevention of coronary artery disease (CAD). Its activity has been found to be affected by a number of pharmacological agents, diet and other factors, thereby becoming a promising target for pharmacological intervention. The PON2 prevents cell mediated lipid peroxidation. However, little is known about the role of PON3. This review describes the structure, gene polymorphism, and factors affecting the activity of PONs, and their role in prevention of CAD.

Non syndromic hearing impairment is a common sensory disorder, which affects one in 600 newborns. Though more than 50 nuclear genes are involved in causing non syndromic hearing impairment, mutations in the connexin 26 (GJB2) gene explain a high proportion of congenital deafness in several populations worldwide. The diversity of genes and genetic loci implicated in hearing loss defines the complexity of the genetic basis of hearing. This review focuses on the role of connexin 26 and mitochondrial 12S rRNA genes in hearing which will be helpful for better understanding of genes in sporadic and aminoglycoside-induced non syndromic hearing impairment.

Stem cells play important role in the development and in the maintenance of specific tissues. They have been identified in majority of the organs like liver, blood, skin and intestine. Role of stem cells in regenerative medicine have been implicated in many chronic diseases. Stem cell research is a new opportunity to those patients whose organs are damaged or diseased. The discovery of stem cells in central and peripheral nervous system is relatively recent. Spinal cord injury is one of the major neurological disaster affecting mostly young lives. Stem cell transplantation in spinal cord injury patients have shown encouraging results. Different sources of stem cells are being exploited for spinal cord injury as well as other neurological disorders.