Biomedical subjects
Publications and source records attributed to V N Gupta.
Canarium manii (Burseraceae) was chemically investigated and the presence of the biflavonoid agathisflavone is reported for the first time from this plant. Pharmacologically, this biflavonoid in doses 50.0 mg and 100.0 mg given orally exhibited dose-dependent hepatoprotective activity against experimentally-induced carbon tetrachloride-hepatotoxicity in rats and mice.
An alcoholic extract of Zizyphus sativa leaves was tested for hypoglycemic activity in normal and alloxan-diabetic rats. Single (100-400 mg/kg) oral doses of extract to normal animals showed a dose-dependent statistically significant lowering of blood glucose 2, 4 and 6 h later. The effect was most pronounced at 6 h with blood glucose returning to control values at 24 h. In alloxan-diabetic rats, no significant effect was observed with extract and tolbutamide. The minimum lethal dose was greater than 3000 mg/kg, orally in mice.
EEG, behavioral and autonomic effects of morphine and clonidine were compared in the unrestrained beagle dog placed in a dimly-lit, sound-attenuated chamber equipped with video monitors. Intravenous (i.v.) morphine (0.5, 1 and 2 mg/kg) and clonidine (11, 33 and 100 microgram/kg) caused parallel dose-related increases in NREM sleep with clonidine being 43 times more potent than morphine. Other similar effects were: an initial transient EEG-behavioral dissociation; increases in spectral power (8-16 Hz); decreases in temperature and heart and respiratory rates; emesis, miosis and salivation. Intraventricular (i.v.t.) morphine (33, 100 and 300 microgram) and clonidine (10 and 30 microgram) caused qualitatively similar EEG, sleep and behavioral effects. Naloxone (30 microgram/kg i.v.) prevented EEG synchrony and behavioral effects of i.v. morphine (1 mg/kg) but not those of i.v. clonidine (100 microgram/kg). Yohimbine pretreatment (0.1 mg/kg i.v.) was more effective in antagonizing clonidine than morphine. These results suggest that morphine and clonidine induce similar EEG, behavioral and autonomic effects through actions upon different receptors on the same or parallel neural pathways. The results further emphasize the importance of an alpha 2-adrenergic-opioid interaction to regulate sleep in the dog.
The attenuation coefficient, propagation velocity and backscattering coefficient were measured in vitro, on freshly excised and functionally impaired rabbit kidneys. subcutaneous glycerol treatment was used to introduce acute renal failure. Elevated plasma creatinine levels, measured prior to the excision of kidneys, were used as an index of the degree of renal functional impairment. Propagation velocity for the ten kidneys ranged between 1538-1575 m/s with that for the normals being 1540 +/- 4 m/s. Velocity was found to increase with increasing renal damage. The attenuation coefficient for all ten kidneys exhibited a linear frequency dependence over the range 3.5-6.5 MHz. The slope of the attenuation coefficient for the glycerol treated kidneys (0.723 dB/cm/MHz) was found to be higher than the slope for the normals (0.499 dB/cm/MHz). The frequency dependence of the backscattering coefficient was not altered by glycerol treatment leading to the postulate that modification of frequency dependent behavior of the attenuation coefficient in this experimental model is primarily due to absorption.
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A microprocessor-based ultrasonic data acquisiton and analysis system has been developed for measuring acoustic parameters of biologic media in a controlled environment. The system consists of commercially available pulse-echo electronics and both minicomputers and microcomputers. Measurements were made on various biologic tissues, both freshly excised and formalin fixed. Propagation velocity measurements were made using the substitution technique. Peak amplitude and log power spectra difference methods were used for attenuation measurements. Measured results indicate that propagation velocity in the soft tissues was in the range of 1530-1580 m/sec at 20 degrees C. Velocity variation among tissues at any given frequency was less than 2%; dispersion in the frequency range 1-10 MHz was approximately 1.5%. Attenuation coefficients showed a marked dependence on frequency increasing in a linear fashion. The slope of the attenuation frequency curve varied with tissue type and could be used for tissue characterization.