PubMed Health⌕ Search

Biomedical subjects

V K Saxena

Publications and source records attributed to V K Saxena.

At least 37 records · Page 2Linked to original sources
PubMed1997

Genetic studies on primary antibody response to sheep erythrocytes in guinea fowl.

1. The primary antibody response to sheep erythrocytes was determined by haemagglutination test in guinea fowl. The effects of various genetic and non-genetic factors on immune response to sheep RBCs in guinea fowl were also estimated. 2. The immune response to sheep RBCs was normally distributed in guinea fowl with mean titre at 1.534 +/- 0.014. 3. In guinea fowl, effects on titre values of sire and variety (feather colour) were significant whereas sex and sex x variety interaction effects were non-significant. 4. The estimate of heritability for immune response to sheep RBCs in guinea fowl was 0.35 +/- 0.17.

Animals↗
PubMed1997

Ixodid ticks infesting rodents and sheep in diverse biotopes of southern India.

A total of 127 rodents were trapped in southern India. Examination of these rodents revealed the presence of 2 species of ticks, Haemaphysalis spinigera and Rhipicephalus ramachandrai. The former species is the principal vector of Kyasanur Forest Disease (KFD) in India, and the latter's role, if any, is unknown. Sheep grazing in 1 of the study area were infested with another ixodid tick. Haemaphysalis intermedia, which is a vector of Bhanja virus in India. The presence of H. spinigera on domestic rats is important from the standpoint of KFD enzootiology. This tick shows a narrow habitat preference but a wide host range. In peridomestic situations, the field rodent Bandicota bengalensis did not harbor any tick species. Contiguity of feral and domestic biotopes in some areas contributed to the transfer of R. ramachandrai from its preferred wild rodent host, Tatera indica, to domestic rats Rattus sp.

Animals↗
PubMed1996

Absence of wild poliovirus circulation among healthy children in a rural area with high oral poliovirus vaccination coverage.

Poliovirus circulation in a rural community was studied by a stool sample survey. No acute paralytic poliomyelitis case had been reported from the study area during the previous 5 months. Immunization coverage in age groups 7 to 12 months and 12 to 60 months was 95.8 and 94 per cent, respectively. Of the 257 children from whom stool samples were collected (about 6% of the child population), 161 (62.6%) were positive for virus isolation. Poliovirus was isolated from 60 (23.3%) children. All three poliovirus types were detected (41 type 1, 16 type 2 and 3 type 3). Intratypic differentiation tests classified these isolates as vaccine-like. Among the children excreting poliovirus, the proportion of those who did not receive polio vaccine within 30 days prior to the sample collection was 46.3, and 68.7 per cent for poliovirus type 1 and 2, respectively. It was concluded that these poliovirus excreting children were infected by the vaccine strains circulating in the environment. The survey showed that wild poliovirus was not detectable within five months after the last case of acute poliomyelitis. Displacement of the wild virus from the environment and circulation of vaccine virus was achieved by high vaccination coverage in this area.

Child Welfare↗
PubMed1994

Local modes in a DNA polymer with hydrogen bond defect.

Vibrations of a homopolymer DNA with localized hydrogen bond defects have been examined using the recently developed decaying mode theory for long-chain polymers with local structural defects. For a poly(dA)-poly(dT) homopolymer having perturbed hydrogen bonds in one base pair, a localized mode at 63.2 cm-1 has been found. This mode has a very nearly pure H-bond stretch or "breathing" character, although the backbones do not separate. This agrees in frequency with a similar result found by other authors using a different approach. We search the full microwave frequency range for other local modes for several models of weakened H bonds. Besides the local mode with breathing characteristics, local modes with other characteristic motions were found, but only for asymmetrically perturbed bonds. We find in general that local modes are not very robust, requiring quite specific, narrow ranges in parameter space. They are also not abundant, there being only three in our most prolific model.

Biophysical Phenomena↗
PubMed1994

Vibrational local modes in DNA polymer.

Where the translational symmetry of a long polymer chain is interrupted, characteristic vibrations of the molecule are possible in which only those atoms at or relatively near the defect site partake of the motion. This contrasts with the more common vibrational states in which the motion propagates along the chain as a sound wave. Examples of readily producible local defects include broken bonds, missing atoms or groups, and extra links as are found, e.g., in thymine dimers. For each different defect, the spectrum of local mode frequencies is characteristic of its structure. Hence the local modes give direct information about the nature of the defect and can serve as a diagnostic signature of the polymer chain lesion. We have developed and are using algorithms and fortran code to predict the existence and nature of local modes based on their atomic structures. We have studied examples of different defects and found their eigen-frequencies and eigenvectors. For the simplest case of a broken hydrogen bond in a single A-T unit in a long homopolymer dA.dT chain, we display stereo views of the vibrating unit side-by-side with the undisturbed molecule for the three local modes occurring below 300 cm-1 in frequency.

Algorithms↗
PubMed1993

An unusual morphological type of Trypanosoma (Herpetosoma) lewisi (Kent, 1880) detected in the blood of Rattus norvegicus in India.

An unusual morphological type of Trypanosoma (Herpetosoma) lewisi (Kent, 1880) which was detected in Rattus norvegicus in India is reported in the present study. This type is different from known types of T. lewisi in that the kinetoplast is at a greater distance from the posterior end (P-K) than the usual type. The total length, including the free flagellum, is 35.3-39.3 microns and P-K is 11.9-15.0 as against total length of 21 to 36.5 microns in the normal form.

Animals↗
PubMed1993

Multiple cerebral infarctions in a young patient with secondary thrombocythemia due to iron deficiency anemia.

A 30-year-old woman developed multiple cerebral infarctions. In the absence of other risk factors, thrombocythemia secondary to iron deficiency anemia due to polymenorrhoea was considered to underlie the cerebral infarctions. Platelet count was normalized after iron therapy. The importance of vigorous treatment of iron deficiency anemia in preventing complications of secondary thrombocythemia is emphasized.

Adult↗
PubMed1992

Inhibition of evoked neurotransmitter release from rat hippocampus by a polypeptide toxin isolated from the marine snail Conus distans.

The active fraction, isolated and partially purified from the crude venom of the marine snail Conus distans, with a molecular mass of about 25 kDa, inhibits neurotransmitter release in rat hippocampus. This toxin (distans Toxin) inhibits the electrically evoked tritium labelled noradrenaline release from rat hippocampal slices in a dose and time dependent manner. The neurotransmitter release is mainly regulated by N-type of voltage sensitive Ca(2+)-channels. The distans toxin behaves as a partial antagonist of calcium in the buffer, possibly by competing with calcium for this type of voltage sensitive Ca(2+)-channels.

Animals↗
PubMed1992

Plasmon interpretation of 25 cm-1 mode in DNA.

An extension of the effective field approach for the normal mode dynamics of dissolved DNA polymers has been applied to study the vibrational modes of DNA-hydration sheath-counterion system, to include the effect of site bound counterions on the system dynamics. An alternative interpretation has been suggested for a 25 cm-1 mode recently observed in DNA samples and interpreted earlier as an interhelical mode. Analysing the eigenvectors this mode is found to possess a large electric dipole moment with longitudinal collective oscillations of the system. These characteristics identify this mode as a collective plasmon mode. Possible physical reasons for the existence of this character have been presented.

Computer Simulation↗
PubMed1992

Ergotamine: its use in the treatment of migraine and its complications.

This paper gives a review of the use of ergotamine in the treatment of migraine and discusses its side effects and the treatment of possible complications. It is concluded that ergotamine is an effective and valuable substance in the treatment of acute attacks of migraine. However, ergotamine remains a potentially dangerous substance, its possible side effects being multiple and in some cases very serious. In view of the important adverse effects, the further study of other molecules effective in the treatment of acute migraine attacks is warranted.

Autonomic Nervous System Diseases↗
PubMed1992

Clinical and pathophysiological aspects of neurological complications in renal failure.

A review of the neurological complications presenting in uremia and an account of their presumed pathophysiology is given. With the introduction of different dialytic procedures during the last twenty years, the incidence and severity of neurological complications have declined. Nevertheless, some disturbances related to the uremic syndrome fail to respond to dialytic therapy and these therapeutic measures may even be responsible for the appearance of some new abnormalities. The clinical manifestations of uremic encephalopathy and polyneuropathy are presented. The review of the presumed pathophysiology of these syndromes illustrates the still existing controversies. Nevertheless, some promising new lines of research are reviewed. In addition, some complications of uremic treatment, including dialysis disequilibrium syndrome and dialysis encephalopathy are presented.

Brain Diseases, Metabolic↗
PubMed1992

Critical appraisal of entomological data of Madhya Pradesh for 1991 and its relevance to the National Malaria Eradication Programme.

Entomological data generated in five entomological zones, of Madhya Pradesh State during 1991 including, Bhopal, Bilaspur, Gwalior, Indore and Raipur were analyzed. The entomological parameters that were studied included per man hour (pmh) density, abdominal physiology and parity status. The inferences were related to i) resting behaviour (exophily/endophily) ii) duration of indoor resting period of mosquitoes iii) man-vector contact iv) efficacy of residual insecticide and v) vulnerability of the area to focal malaria outbreaks. The data chiefly pertains to the putative malaria vector Anopheles culicifacies in all the five zones under study. The studies have brought out that A. culicifacies, traditionally endophilic and endophagic, has demonstrated radical departure in its resting and feeding behaviour. In Gwalior zone the species shows high preference for exophily. In Bhopal and Indore zones there is differential resting behaviour with respect to season. The species shows, for most part of the year exophily but is also endophilic during post monsoon period. In Bilaspur zone the species shows marked exophily and endophagy. Irrigation practices seem to have affected the mosquito population density patterns in these regions as brought out in Indore and Bilaspur zone, where high density pattern is observed between November and February. These findings have obvious implications in selecting the appropriate intervention methods and the period of spray in areas where residual spray is the method of choice for interruption of transmission.

Animals↗
PubMed1991

Low-frequency parameterization of hydrogen bonding.

We review the model of the hydrogen bond developed by Lippincott and Schroeder and discuss the frequency range in which it is valid, specifically in the optical and near infrared range. We then show why and how to modify the Lippincott and Schroeder formulate to apply to the far infrared and lower ranges. The contrasts between the old and modified systems, particularly with respect to the effective force constants are worked out and plotted for an example.

DNA↗
PubMed1990

Monitoring of temephos (abate) application as a cyclopicide under the guineaworm eradication programme in India.

Temephos application in unsafe water sources at a dose of 1ppm, which started in 1986, is an important activity of the guineaworm eradication programme in India. During March 1989, monitoring of temephos application was carried out in six villages in each of the five guineaworm endemic districts: Kurnool (Andhra Pradesh), Gulbarga (Karnataka), Dhar (Madhya Pradesh), Thane (Maharashtra) and Jhalawar (Rajasthan), selected for the study. Out of 62 unsafe water sources targeted in the sampled villages for temephos treatment, 43 were treated during 1989 in the five districts (coverage 69.35 per cent). Out of these 43 treated sources 79.1 per cent were free of cyclops and the rest 20.93 per cent showed a variable cyclops count. 117 adult cyclops identified from these sources included Mesocyclops byalinus (82) and M. leuckarti (35). People's perception of utility of chemical treatment of water sources varied from negligibly low to moderate levels. Those areas which received timely application of temephos during the preceding year, al sharp decline in the number of cases in 1989 was observed. However, in those villages where no temephos was applied or where application was started as late as April or May, there was no impact on prevalence of the disease.

Animals↗
PubMed1990

Biometrical variations in haematophagous arthropods. II. DV/D ratio of male terminalia of wild Culex quinquefasciatus SAY (Diptera: Culicidae) in India.

The DV/D ratio of male terminalia is considered as most reliable morphometric feature to distinguish Culex pipiens from Cx. quinquefasciatus. In India although only Cx. quinquefasciatus is known both in the filariasis (Bancroftian) endemic and non-endemic areas, there has been no study on the amounts of morphometric variation among wild strains of this species. This paper reports variation in the DV/D ratio of Cx. quinquefasciatus collected from 7 localities of Delhi (D), Lucknow (L), Patna (P), Varanasi (V), Rajahmundry (R), Jabua (J) and Alleppey (A) between June and October 1986. The mean value of DV/D ratio in all the strains varied from 0.78 to 0.99 with overall mean of 0.89. The range of the ratios was 0.30 to 1.88. There were 1.28 per cent specimens (9 out of 700) with ratio below 0.50 and the rest 98.72 per cent with ratio 0.50 and above. The DV/D ratio of 0.50 should therefore be accepted as lower limit for Cx. quinquefasciatus instead of the earlier established value of 0.40. The coefficient of variation (CV) among the 7 strains indicates the following progression of variability in the DV/D ratio from most stable to most variable strain: L greater than V greater than R greater than A greater than J greater than P greater than D. The range of mean CV values in different strains was very close with most stable L strain 19.19 and most variable D strain 25.92. The amounts of variation, as estimated by coefficient of variation, were found to be significantly different between the following strains: Delhi and Lucknow (P less than 0.01 at 198 df), Lucknow and Patna (P less than 0.05 at 198 df), and Delhi and Varanasi (P less than 0.05 at 198 df).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Relationship between external calcium concentration and noradrenaline- and neuropeptide Y-evoked release from perfused dog spleen.

Several neuropeptides have been demonstrated to coexist with classical neurotransmitters in the central and peripheral nervous systems and have been proposed as neurotransmitter or neuromodulator candidates. In this report, we investigated the relationship between the external calcium concentration and the electrically induced overflow of noradrenaline (NA) and neuropeptide Y (NPY) in dog perfused spleen. Perfusion solutions with calcium concentrations ranging from 0 to 10 mM were applied. The splenic nerves were electrically stimulated at 16 Hz. For NA analysis high-pressure liquid chromatography with electrochemical detection was used. NPY was determined by radioimmunoassay. The perfusion pressure and the overflow of NA and NPY increased in a calcium concentration dependent manner. The calcium concentration dependency of the overflow of NA and NPY was comparable, indicating a co-release of the two substances. The molar ratio of NA/NPY remained unchanged over the calcium concentration range applied and the half maximal saturation values for release of NA (5.55 mM) and NPY (6.66 mM) were similar. These results indicate that the preferential release of NPY at high frequency stimulation as previously shown in the pig spleen, if present in the dog, is not the result of a difference in calcium dependency of the evoked release of NA and NPY.

Animals↗