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Biomedical subjects

A B Chowdhury

Publications and source records attributed to A B Chowdhury.

At least 19 recordsLinked to original sources
PubMed2001

Leaf surfaces and the bioavailability of pesticide residues.

Laboratory bioassays were carried out to determine the toxicity to Folsomia candida Willem (Collembola: Isotomidae) of residues of a pyrethroid insecticide, deltamethrin, and an organophosphorus insecticide, dimethoate, on different leaf surfaces. The test leaves included a range of species and leaves of different ages. Dose-response relationships were estimated for F candida walking over the various treated leaf substrates. Probit analysis was used to estimate the means and standard deviations of the associated tolerance distributions expressed as gAIha-1. Parallelism tests were undertaken to compare the susceptibilities of F candida to the two compounds applied to the different leaf surfaces. On deltamethrin-treated leaf surfaces, the LD50 values for F candida varied from 6.36 to 77.14 gAIha-1. F candida was least susceptible to deltamethrin residues when applied to leaves of dwarf bean (Phaseolus vulgarus L) and the highest susceptibility was observed following application to leaves of seedlings of barley (Hordeum vulgare L). In contrast, the LD50 values observed for dimethoate treatments did not differ significantly between leaf types, ranging from 1.35 to 8.69 gAIha-1. The laboratory data on susceptibility of F candida on different leaf types for different pesticides can be used to investigate the role of leaf surface properties in modifying the toxicity of applied pesticides to exposed invertebrates.

Animals↗
PubMed1991

Leishmanial blepharo-conjunctivitis.

We describe a case of blepharo-conjunctivitis due to Leishmania donovani in association with nodules of post kala azar dermal leishmaniasis (PKDL) on the chin. The diagnosis was confirmed by isolation of the parasite in culture. Direct implantation of the parasite by contaminated fingers from the chin nodules to the eye is suggested as the mode of spread. The role of cell-mediated immunity, (CMI) in restricting the skin lesions on the chin for 37 years at the same site, was suspected. This is only the second report of ocular involvement in L. donovani infection from India.

Agglutination Tests↗
PubMed1988

Modulation of the cell-mediated immune response in kala-azar and post-kala-azar dermal leishmaniasis in relation to chemotherapy.

Cell-mediated immune (CMI) response and the concurrent clinical events were studied longitudinally before, during and after treatment in 24 kala-azar (KA) and ten post-kala-azar dermal leishmaniasis (PKADL) patients for a period of six months. The status of specific CMI response was estimated by in vitro tests, viz. lymphocyte transformation and leucocyte migration inhibition in response to L. donovani antigen. The generalized CMI response was assessed by lymphocyte transformation in the presence of mitogen (phytohaemagglutinin) and quantitation of the circulatory T-lymphocyte population. To measure the drug response, the extent of clinical improvement following treatment was used as a yardstick. The results showed that suppression of the CMI response was both specific and generalized in nature during the active stage of KA; but in PKADL, unlike in KA, suppression of the CMI response was found to be associated only at the specific level. With administration of the drug (sodium antimony gluconate), the immunosuppression was gradually eliminated with concomitant clinical improvement in both KA and PKADL patients, although the latter took a longer period of time and a larger amount of drugs compared to the former.

Adolescent↗
PubMed1987

Leishmanin test survey in an endemic village of Indian kala-azar near Calcutta.

A leishmanin test survey was carried out in a village during the declining phase of an outbreak of Indian kala-azar. One hundred and fifty of the total population of 220, including 25 clinically cured cases of kala-azar, were available for this study. Nineteen per cent (24 of 125) of the otherwise normal subjects showed delayed hypersensitivity to leishmanin antigen. The majority of these were household contacts of kala-azar patients, and the remainder came from the close neighbourhood. This may support the view that microfoci are of importance in the spread of the disease. The age-specific profile of leishmanin positivity was found to increase steadily, attaining a high level in older age groups.

Adolescent↗
PubMed1986

B lymphocyte population and immunoglobulins in Indian kala-azar in response to chemotherapy.

The levels of immunoglobulin classes (IgG, IgM and IgA) along with B lymphocyte population size were estimated in 24 kala-azar (KA) patients and results were compared with those obtained from 30 controls. A marked increase in the level of IgG and to a lesser extent in that of IgM was noted in the sera of KA patients. But, no such difference could be noted in serum IgA level. Along with the increased levels of immunoglobulins the elevation of B lymphocyte population size was also observed. Follow-up studies during and after chemotherapy for the period of 8 months showed that clinical improvement in KA patients resulting from treatment had a positive correlation with the progressive decline in the B lymphocyte population and in the level of immunoglobulin though the latter, particularly IgG, took a longer time to return to normal.

Adolescent↗
PubMed1978

Population biology of hookworms in children in rural West Bengal. I. General parasitological observations.

Hookworm infection was studied over a 22-month period in 31-49% of a population of 1,803 1- to 10-year-old children in a rural area near Calcutta where both Necator americanus and Ancylostoma duodenale were prevalent. Half of the children were infected before age 5 and 90% were infected by age 9, when the mean egg count reached 2,000 eggs/g of feces. Infection was significantly heavier and more prevalent among males than among females, and greater among Muslims than among Hindus. These differences were apparent in children less than 2 years of age. Numerical factors were devised to adjust fecal egg counts for both the smaller fecal output of children and the increased dilution of eggs in watery feces as compared to formed feces. It is proposed that egg counts from 1- to 3-year-olds be multiplied by 0.3, those from 4- to 6-year-olds by 0.5, those from 7- to 9-year-olds by 0.6, and those from 10 to 12-year-olds by 0.7; differences in mean egg density among various fecal consistencies produced factors of 1, 1.5, 2, 3, and 3.5 by which the egg counts in formed, mushy-formed, mushy, mushy-diarrheic, and diarrheic feces should be increased.

Age Factors↗
PubMed1978

Population biology of hookworms in children in rural West Bengal. II. Acquisition and loss of hookworms.

From changes in hookworm egg counts in feces of children in Gangetic West Bengal we estimate that, on the average, each child lost about 11.1 female hookworms during the 1969 post-monsoon dry period and gained about 10.3 females during the subsequent premonsoon and monsoon seasons, resulting in a net loss of worms over the 22-month study period. However, the mean fecal egg count for each 1-year age group of children from 3-11 years suggests an average net gain of 2.7 female worms/year. From seasonal changes in the relative abundance of larvae recovered from fecal cultures, it is estimated that at least 82% of the yearly gain in Ancylostoma duodenale females is a result of the maturation of hypobiotic (latent) larvae acquired during the previous wet season. A duodenale was present about equally with Necator americanus but it was significantly more common among males than among females, and more common among Muslims than among Hindus. Using damp gauze pads, we sampled the soil surface around freshly-passed feces for infective hookworm larvae and estimated that 252 larvae were contacted by each child durint the transmission season. Efficiency of penetration and maturation of each hookworm species was calculated from estimated larval densities on the soil surface, from seasonal changes in fecal egg counts, and from variations in the number of larvae recovered from fecal cultures by season and age of the host; it is estimated that N. americanus is 17.5% efficient and A. duodenale 5.3%. Children negative for hookworm became positive at all times of the year and at a significantly higher rate in 1970 than in 1969; incidence averaged 4.2% per 2-month period and mean initial fecal egg count suggested infection with about 2.0 female worms. The average life span for N. americanus is calculated to be 3-4 years and that of A. duodenale about 1 year under the conditions of reinfection found in the study area.

Ancylostoma↗
PubMed1976

Clinical manifestations of Bancroftian filariasis in a suburb of Calcutta, India.

Interviews and physical examinations for filarial disease were conducted in Howrah near Calcutta, West Bengal, India, in a study area where long term quantitative entomological studies have disclosed high intensity, year round exposure to Wuchereria bancrofti. Little elephantiasis or other serious filariasis-related disease was noted, but half the males over 20 years of age had genital lesions of various types. Ninety-two percent of households had at least one resident with microfilaremia or presumptive clinical evidence of filarial disease.

Adolescent↗