NISCAIR Online Periodicals Repository Collection: IJBB Vol.36(5) [October 1999]

Effect of amplitude modulated RF radiation on calcium ion efflux and ODC activity in chronically exposed rat brain

Tue, 28 Sep 1999 22:58:59 GMT

Title: Effect of amplitude modulated RF radiation on calcium ion efflux and ODC activity in chronically exposed rat brain

Authors: Paulraj, R; Behari, J; Rao, A R

Abstract: The effect of exposing rats to amplitude modulated radiofrequency radiation (112 MHz modulated to 16 Hz) during development and growth has been examined. Wistar rats ( 35 days old) when exposed at above frequency at the power level 1.0 mW/cm² (SAR, 0.75 W/kg) for 35 days showed enhanced ornithine decarboxylase activity and Ca²⁺ efflux in brain indicating potential health hazards due to exposure.

Page(s): 337-340

Monte Carlo simulation of photon scattering in biological tissue models

Tue, 28 Sep 1999 22:58:59 GMT

Title: Monte Carlo simulation of photon scattering in biological tissue models

Authors: Kumar, D; Chacko, Susamma; Singh, Megha

Abstract: Monte Carlo simulation of photon scattering, with and without abnormal tissue placed at various locations in the rectangular, semi-circular and semi-elliptical tissue models, has been carried out. The absorption coefficient of the tissue considered as abnormal is high and its scattering coefficient low compared to that of the control tissue. The placement of the abnormality at various locations within the models affects the transmission and surface emission of photons at various locations. The scattered photons originating from deeper layers make the maximum contribution at farther distances from the beam entry point. The contribution of various layers to photon scattering provides valuable data on variability of internal composition.

Page(s): 330-336

Pathways of glucose catabolism in procyclic Trypanosoma congolense

Tue, 28 Sep 1999 22:58:59 GMT

Title: Pathways of glucose catabolism in procyclic Trypanosoma congolense

Authors: Obungu, Victor H; Kiaira, Job K; Olembo, Norah K; Njogu, Muturi R

Abstract: Studies of respiration on glucose in procyclic Trypanosoma congolense in the presence of rotenone,antimycin, cyanide, salicylhydroxamic acid and malonate have indicated the presence of NADH dehydrogenase, cytochrome b-c₁, cytochrome aa_3, trypanosome alternate oxidase and NADH fumarate reductase/succinate dehydrogenase pathway that contributes electrons to coenzyme Q of the respiratory chain. The rotenone sensitive NADH dehydrogenase, the trypanosome alternate oxidase, and cytochrome aa₃, accounted for 24.5±6.5, 36.2±4.2 and 54.1±5.5% respectively of the total respiration. Activities of lactate dehydrogenase, NAD⁺- linked malic enzyme and pyruvate kinase were less than 6 nanomoles/min/mg protein suggesting that they play a minor role in energy metabolism of the parasite. Phosphoenolpyruvate carboxy kinase, pyruvate dehydrogenase, succinate dehydrogenase, NADP⁺-linked malic enzyme, ADH fumarate reductase, malate dehydrogenase, and α-ketoglutarate dehydrogenase and glycerol kinase on the other hand had specific activities greater than 60 nanomoles/min/mg protein. These enzyme activities could account for the production of pyruvate, acetate, succinate and glycerol. The results further show that the amount of glycerol produced was 35-48% of the combined total of pyruvate, acetate and succinate produced. It is apparent that some of the glycerol 3-phosphate produced in glycolysis in the presence of salicylhydroxamic acid is dephosphorylated to form glycerol while the rest is oxidised via cytochrome aa₃, to form acetate, succinate and pyruvate.

Page(s): 305-311

Microwave absorption in oligomers of ethylene glycol

Tue, 28 Sep 1999 22:58:59 GMT

Title: Microwave absorption in oligomers of ethylene glycol

Authors: Sengwa, R J; Kaur, Kulvinder

Abstract: The dielectric properties of biologically and pharmaceutically important low-molecular weight ethylene glycols H(-OCH₂CH₂-)_n -OH (n=1,2,4,6) were investigated to clarify the effect of chain length on the dielectric properties. The measurement of dielectric constant and dielectric loss was carried out over the frequency range 200 MHz to 20 GHz at temperatures of 25°C to 55°C. It is found that in these molecules microwave dielectric losses are significant. The dispersion behavior of these molecules can be represented by Cole-Cole equation. The dielectric properties of these homologous ethylene glycols are discussed in terms of the effects of chain length and intermolecular hydrogen bonds regarding the molecular conformations. These wide frequency range dielectric data have also been discussed in view of the suitable selection of the oligomer of ethylene glycol for cosmetic preparations and other pharmaceutical applications with the intention of protection of the skin from weak microwave radiations present in the surrounding environment. These systematic microwave dielectric data with frequency and temperature variation are not available and are provided in this paper.

Page(s): 325-329