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Biomedical subjects

V K Saxena

Publications and source records attributed to V K Saxena.

At least 55 records · Page 3Linked to original sources
PubMed1989

The effect of thalamic stimulation in processing of verbal stimuli in dichotic listening tasks: a case study.

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct anatomic connection with the left dominant hemisphere. The role played by extralinguistic factors, such as attention and functional tuning of the associated cortical structures, has not been carefully examined. This investigation was undertaken to evaluate the effects of the left thalamic electric stimulation on the processing (recognition and recall) of dichotically presented CVC verbal stimuli in a patient being treated for chronic pain. We report the positive effects of electric stimulation (confirmed by increased subcortical metabolic activity using SPECT, a brain imaging technique) on the processing of dichotically presented verbal stimuli.

Attention↗
PubMed1989

Calculation of water volume in step wells for cyclopicide application and its eco-epidemiological implication: mathematical validation of some theoretical considerations.

Chemical treatment of step wells to kill cyclopoid vectors of guinea worm by temephos (50 per cent E. C.) at the dose of 1 ppm is now an important activity of the guineaworm eradication programme in India. Calculation of correct volume of water in step wells, to determine the exact quantity of temephos to be applied, therefore, deserves adequate attention to prevent over and underdosing of stepwells by the chemical. The prescribed method of calculation of water volume includes two formulae; pi r2h and 1 x b x h (where h = mean depth for uneven bottoms and is a single depth measurement for almost even bottoms). Field observations revealed that in many stepwells there were marked variations in depth within the same well. These differences in depth ranged from small to very large in some wells. Since these depth variations would lead to miscalculation of water volume by existing method and the dose of temephos to be applied, with eco-epidemiological consequences, new formulae have therefore been deduced for conceivable patterns of depth variations by geometrical and algebric applications. The new formulae will permit calculation of, nearest to, exact quantity of temephos required for application. These formulae have been validated by an example.

Animals↗
PubMed1989

Chigger mite infestation of small mammals in a feral biotope of a public park area of south Delhi.

Examination of Bandicota bengalensis (8) and Suncus murinus (4) trapped in a feral biotope of a public park area of south Delhi revealed presence of the known scrub typhus vector Leptotrombidium (L.) deliense, the suspected vector Gahrliepia (S.) ligula and Gahrliepia (Walchia) sp. of chigger mites, on them. The epidemiologically important population indices (chigger infestation rate-CIR and incidence rate--1R) were estimated. The overall CIR of the three mite species on the hosts was 2.83 mite/host, and that of L. deliense on B. bengalensis and S. murinus was 1.62 and 0.25 respectively, whereas that of G. ligula was 0.50 on both the host species. The overall 1R was 66.66 per cent being 62.5 per cent for B. bengalensis and 75.0 per cent for S. murinus. Incidence of L. deliense on B. bengalensis was higher (62.5 per cent) than on S. murinus (25.0 per cent), whereas IR of G. ligula was higher (50.0 per cent) on S. murinus than on B. bengalensis (25.0 per cent). The Chi square test of independence has shown that these chigger species are not host specific, but are rather habitat specific. Chiggers were absent on Mus platythrix from a habitat about 40 meters away from the B. bengalensis and S. murinus collection sites. The high CIR value for scrub typhus vector L. deliense (1.62) warrant investigations on natural infection rates of R. tsutsugamushi in the chiggers and screening of local human population for the infection.

Animals↗
PubMed1988

Facilitation of the release of noradrenaline and neuropeptide Y by the alpha 2-adrenoceptor blocking agents idazoxan and hydergine in the dog spleen.

The release of noradrenaline (NA) together with its possible cotransmitter neuropeptide Y (NPY) was investigated in the perfused dog spleen. The splenic nerve was stimulated electrically at high frequency with bursts, which evoked a simultaneous release of both substances. Infusion of the alpha 2-adrenergic blocking agents idazoxan or hydergine enhanced the amount of NA and NPY in the venous effluent. The present results demonstrate the concomitant release of a classical neurotransmitter and a neuropeptide, and suggest that at high frequency stimulation, regulation of their release operates very similarly.

Adrenergic alpha-Antagonists↗
PubMed1987

Thalamic functional tuning of the cortex in dichotic listening tasks.

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct access to the linguistically dominant left hemisphere. The roles played by the extralinguistic factors, such as induced attentiveness and functional tuning of the auditory system, have not been carefully examined. The evidence for the facilitating effects of subcortical stimulation on processing dichotic stimuli is presented.

Dichotic Listening Tests↗
PubMed1986

Comparison of single-photon emission computed tomography with [123I]iodoamphetamine and xenon-enhanced computed tomography for assessing regional cerebral blood flow.

Regional CBF (rCBF) images obtained from xenon-enhanced computed tomography (XeCT) and single-photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP) done with a rotating gamma-camera were compared in nine patients. Both XeCT and SPECT/IMP demonstrated flow abnormalities at all sites of infarction identified by CT, while detecting reduced rCBF in areas normal by CT in eight of the nine patients. All areas that were abnormal on XeCT were abnormal on the comparable SPECT/IMP images. The major advantages of XeCT are its greater resolution and potential for noninvasive quantitation of rCBF, while the major advantage of SPECT/IMP is its visualization of the entire brain on transverse, coronal, and sagittal sections.

Amphetamines↗