Biomedical subjects
Publications and source records attributed to A K Hati.
An in vivo chloroquine resistant P. falciparum malaria case is reported from Calcutta. The resistance level being R-1. The patient responded well to pyrimethamine and sulfadoxine combination, which appears to be the drug of choice in Calcutta for choloroquine resistant P. falciparum malaria as quinine is not available.
Russell's viper venom detoxified by gamma (gamma)-radiation (100 kR or 200 kR) was used as a toxoid for active immunization of rabbits following a short or long schedule of immunization without any adjuvant. Effective neutralization of venom toxin by immune sera of rabbits was observed with both schedules. Sera of rabbits immunized with 100 kR irradiated venom toxoid (100 kR toxoid antisera) were more potent than 200 kR toxoid antisera. The presence of antibody in the immune sera was detected by immunoelectrophoresis. The effect of gamma-radiation on some enzymes and venom protein profiles was studied. Phosphodiesterase, protease and hyaluronidase were inhibited by radiation though phospholipase A activity remained unaffected. Radiation did not produce any gross change in the protein profile of crude viper venom. Phosphodiesterase and protease activities of viper venom were neutralized more effectively by 100 kR toxoid antisera in the short schedule than in the long schedule of immunization.
Batches of hungry Aedes aegypti mosquitoes which partially sucked blood from the skin lesions of proved untreated lepromatous leprosy (LL) patients were allowed immediately to feed on a portion of the skin of a cleanly shaved swiss mouse. The portion of the skin was cut, homogenized on the same day and extracted with chloroform. Out of 10 extracts, stained for acid fast bacilli (AFB), Mycobacterium leprae were demonstrated in eight, indicating transfer of bacilli mechanically to the biting spot through intermittent feeding. Out of 50 probosces dissected and stained for AFB, M. leprae were demonstrated in 45.
Prick skin tests on 200 patients with a history of sensitivity to dust were done against house dust, cockroach, D. pteronyssinus, and D. farinae antigenic extracts. The frequency of positive reaction was 35% to cockroach, 59% to house dust, 84.7% to D. farinae, and 54% to D. pteronyssinus. Distinctively different prevalence of the three antigens, cockroach, house dust, and mites suggest that cockroach antigen is a specific antigen independent from house dust and mite antigens.
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The annual transmission potential of Wuchereria bancrofti was calculated from the number of infective larvae found in the number of Culex quinquefasciatus expected to bite an individual exposed 24 hr a day for a year in Calcutta and in a rural (Memari) area. In Calcutta, an average of 151 mosquitoes/night/person were collected; it was calculated that 55,028 mosquitoes could bite a person per year, including an average of 177 infective mosquitoes containing 319 infective larvae of W. bancrofti. At Memari, an average of 284 mosquitoes/night/person were collected; here with the resulting calculation was that 103,718 mosquitoes could bite a person per year, including an average of 137 infective mosquitoes containing 223 infective larvae. The annual transmission potential was higher in the urban area than that in the rural area. Annual transmission potential is useful knowledge in the epidemiological assessment of transmission dynamics for the formulation of control strategies.
In Calcutta adult Anopheles stephensi mosquitoes were captured in significantly greater numbers from temporary human shelters than from their conventional resting places, such as brick built indoor rooms and cattlesheds, pointing out a change of behaviour in seeking their resting places which may have occurred due to excitorepelletory action of insecticides used indoors in bygone days.
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In the District of Burdwan, a rural area of West Bengal State, India, Japanese encephalitis (JE) virus is endemic. In one village a longitudinal survey was conducted in order to find out whether associations could be established between the density of the vector mosquito Culex vishnui in two types of resting places, the incidence of infections in sentinel chicks exposed at monthly intervals, the prevalence of antibodies in wild birds and the occurrence of clinical infections in the human population. The experiment lasted from August 1981 till August 1982. Meteorologically a summer season (March-June), a rainy season (July-October) and a winter season (November-February) are distinguished. In the sentinel chicks infections were observed in all three seasons; in wild birds antibodies were prevalent throughout the year; these observations suggest perennial transmission of the virus in its maintenance cycle. Human infections were observed periodically with, in August 1982, a pronounced peak; this may point to fluctuations in the level of circulation of the virus in its maintenance cycle and spillover to the human population at times of peak circulation. The peaks may be related to the influx of young non-immune birds and newborn mammals into the animal population in summer. Further studies, including virus isolation attempts from mosquitoes and nestling birds, are required to prove this hypothesis.
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A study on host preference of P. argentipes in two different biotopes was conducted by capturing the flies from cowsheds and human dwellings. The human blood index of P. argentipes collected from cowsheds was 21.5% and 69.6% when collected from human dwellings; this indicates that host preference of P. argentipes varies widely in different biotopes.