Biomedical subjects
J Behari
Publications and source records attributed to J Behari.
Electrostimulation and bone fracture healing.
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Physiological changes in rats after exposure to low levels of microwaves.
The effects of exposure to sublethal levels of microwaves were studied. Young albino rats of both sexes were exposed for 60 days to 7.5-GHz microwaves (1.0-KHz square wave modulation, average power 0.6 mW/cm2) for 3 h daily. During and after microwave exposure several physiological parameters were measured in both control and exposed animals. It was found that the animals exposed to microwaves tended to eat and drink less and thus showed a smaller gain in body weight. Some of the hematological parameters and organ weights were also significantly different. It is proposed that a nonspecific stress response due to microwave exposure and mediated through the central nervous system is responsible for the observed physiological changes.
Electrical parameters of bone substrate in microstrip line configuration.
Techniques of microstrip line are extended to study the dielectric properties of bone at 4.5 GHz. The method is based on time domain technique and is applicable to higher frequency ranges where other conventional methods of dielectric measurements are not suitable. It is found that this method serves well for the determination of dielectric constants of bone in two orthogonal directions.
Biophysical characterization of osteoporotic bone.
A number of biophysical and biochemical parameters have been measured in normal and osteoporotic animals and their bones. Rats have been fed normal and calcium- and phosphorus-deficient diets (through mineral content) from the weaning period to maturity (greater than 125 days). The experiments were performed after attaining this age. Biochemical parameters considered for comparison included: red blood cells (RBC), white blood cells (WBC), Hb, serum calcium and phosphorus, blood pH, PCO2, and PO2. Bones obtained after sacrificing mature animals were used for obtaining data regarding infrared, fluorescence, and X-ray spectra, and transmission electron micrographs, and were also subjected to spectrochemical analysis. It was found that the two sets of results show differences in most of the above-mentioned parameters, which correlates well with the loss of calcium and phosphorus metabolism and the corresponding increase in the amorphous-to-crystalline ratio. It is hoped that these data will be useful in characterizing the osteoporotic bone and will suggest the mechanism for reversal by external stimulations.
On the solid state of bone.
Photovoltaic effect (infrared and visible light) is observed in bone and its two major components, collagen and apatite, at room temperature. A dimunition in the magnitude of photovoltage is observed after exposure to ultraviolet light in all the cases. The drift mobility of the charge carriers is obtained by measuring I versus V relationships in sandwich samples and relating them to the permittivity of the medium. Lifetime of the injected carriers is measured in the usual way. The data are consistent with the hypothesis that the effects are due to protonic conduction phenomena.
Generation of Hall voltage in bone.
Hall type voltage has been observed in bone and its two major components (collagen and apatite) in the region of moderately high electric and magnetic fields. The configuration of the sample placement and the experimental set up was the same as that adopted in standard Hall measurements. The resistivity of the sample has been related to the Hall Coefficients through the standard relationship and an estimate of Hall mobility was made. The Hall Coefficients were found to be of the order of 10(6) cm3 col-1 while the Hall mobility generally was in the region of less than 1 cm2/volt sec. A comparison with drift mobility suggests that the latter is at least two to three orders of magnitude less than the former. A possible mechanism underlying the said transport phenomena is discussed.
Comparative toxicity of trivalent and hexavalent chromium to rabbits. III. Biochemical and histological changes in testicular tissue.
The administration of trivalent and hexavalent chromium compounds produced inhibition of the activity of succinic dehydrogenase, adenosine triphosphatase and acid phosphattase accompanied by cellular degeneration with complete absence of spermatocytes in the testis of rabbits. The biochemical and histological changes were more marked in the animals treated with the trivalent chromium than those exposed to hexavalent chromium and were progressive with the duration of exposure.
Absorption spectra of bone.
Absorption spectra of human bone and its two major constituents (collagen and apatite) were obtained in the wavelength region extending from 2000 to 12,000 A. In the last two cases a minimum transmission (maximum absorption) was uniformly observed in the ultraviolet region. The two samples after exposure to ultraviolet radiations show a shift in the peak positions. Absorption peaks in the total bone spectra are not reproducible in its two constituents. After exposure to UV radiations the position of maximum absorption is displaced. A possible interpretation of the observed results is presented.
Biochemical and morphological changes in some organs of rats in nickel intoxication.
Biochemical and histological alterations in liver, kidney, testis and myocardium of albino rats were investigated at various intervals after daily administration of nickel sulphate. No significant changes were observed during the initial periods of the treatment, but longer exposures produced marked enzymatic and histopathological alterations in all the four organs examined. The severity of the histological lesions was found to be directly related to the duration of the treatment.
Effect of monazite on body organs of rats.
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The effect of ultraviolet radiation on the electrical conductivity of human bone.
The electrical conductivity of intact bone, collagen and apatite mineral was determined in the region of moderately high fields. After exposure to ultraviolet (UV) radiation the conductivity of the specimens was redetermined. Following exposure marked decreases in electrical conductivity occurred in all specimens. The possible modes of interaction of UV radiation with bone are discussed. It is suggested that protonic conduction may be an important mode of charge transport in bone.