ESTIMATION OF TIME SINCE DEATH FROM THE CHANGES IN VITREOUS HUMOUR SODIUM (Na+) AND POTASSIUM (K+) LEVEL

Background: For investigation of crime, it is very important to determine ‘time since death’ i.e. the interval between death and the time of postmortem examination also called as ‘postmortem interval. This is very important in criminal cases as it shows the track to the investigators to reach the suspected person and to obligate the innocent ones. Methods: The present study was conducted in Forensic Medicine Department on cases died in Dr. S.N. Medical College & associated Group of Hospitals, Jodhpur in association with Department of Biochemistry. Results: The linear correlation of the vitreous sodium (Na+) ion concentration was found statistically insignificant (r=0.045) therefore the coefficient of correlation could not be derived. Conclusion: We have observed linear rise of potassium (K+) ion concentration in the vitreous humour. The linear relationship of the increase in vitreous potassium (K+) ion concentration with increasing postmortem interval is both arithmatic as well as logarithmatic (statistically significant). Keywords: Na, K, Postmortem.

Synthesis and Characterization of Polydimethylsiloxane (PDMS) with Medium Viscosity via Ring-Opening Polymerization

Duration of use and injectability are external factors for Polydimethylsiloxane (PDMS) that needs to be considered when PDMS utilized as a vitreous substituted liquid in vitreoretinal surgery. In general, PDMS which has been used as a substitute for vitreous humour is PDMS with a low viscosity in the value about 1000 cSt and a high viscosity at a value of about 5000 cSt. Various deficiencies have been encountered from low and high viscosity of PDMS, causing research to be continued to obtain PDMS which has suitable properties as a substitute for vitreous humour. One of them is research to obtain medium viscosity of PDMS with a viscosity value of about 2000 cSt. Here, we reported synthesis and characterization of PDMS with medium viscosity in ranges from 1800 to 2600 mPas. PDMS was synthesized through Ring-Opening Polymerization (ROP) pathway using the monomer of Octamethylcyclotetrasiloxane (D4) and the chain terminator of Hexamethyldisiloxane (MM). Various concentrations of potassium hydroxide (KOH) of 3, 4, 6 and 8 %(w/v) were applied as initiator to form gel of PDMS. All synthesized PDMS samples were identified to have viscosity values of 1800-2600 mPas, refractive index values of 1.4042-1.4044 and surface tension values of 22-23 mN/m. Meanwhile, the results of Fourier-Transform Infrared (FTIR) measurement showed that the absorption peaks were similar to that of our previous report.

The Vitreous Body and Its Role in the Diagnosis of Eye Pathologies

Vitreous humour is a biologically weak immune cavity of the eye, and is in some way isolated from pathogens of the rest of the organism due to a series of special immunological privileges. However, it is a place where processes of varied ethiology (immune, infectious or neoplastic) can develop indirectly due to leakage or release of molecules or even cells into the vitreous chamber, or may be the receptacle of molecules derived from processes developed in other organs in close contact with the vitreous (such as the retina or other underlying layers such as the choroid), which makes the vitreous body an accessible place for diagnosis and with less potential for side effects for analysis than other adjacent eye structures. This article reviews the most frequent pathologies that requires vitreous diagnosis, the most commonly used approaches for sampling and the diagnostic tests that can be performed on vitreous samples.