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Biomedical subjects

A Mittal

Publications and source records attributed to A Mittal.

At least 73 records · Page 4Linked to original sources
PubMed1989

Accessory cell heterogeneity in lepromatous leprosy; dendritic cells and not monocytes support T cell responses.

Dendritic cell (DC)-enriched cell populations from anergic lepromatous leprosy (LL) patients were found to be several-hundred-fold more efficient than monocytes (MO) in promoting antigen-induced T cell responses in autologous accessory + T cell cultures. Whereas, the use of autologous monocytes over a wide concentration range failed to stimulate Mycobacterium leprae-induced T cell proliferation, DC at concentrations as low as 0.1% induced significant proliferation in 9/15 and interferon gamma production in 14/15 LL patients. Four of the LL patients who failed to show proliferation were, however, able to secrete interferon gamma in the same T cell + DC co-cultures. DC were able to present particulate leprae antigens to autologous T cells. This preference for DC as an accessory cell was not shown when the cross-reacting antigen PPD was used in parallel co-cultures. Though tuberculoid leprosy patients showed some improvement in T cell proliferation with DC as compared to MO constituted co-cultures, this was not statistically significant. These results suggest that there is a heterogeneity in accessory cell requirement across the leprosy spectrum and that many lepromatous patients possess M. leprae-reactive functional T cells.

Antigens, Bacterial↗
PubMed1988

Fungal infections of ear with special reference to chronic suppurative otitis media.

Fungus were found to take important role in ear infections of the 344 patients (CSOM 286, Otomycosis 44, Otitis externa 14), significant fungal infections (with positive smear and culture) were detected on 49%, 79.5%, 66.6% patients respectively. 84.8% patients were detected both by smear and culture, 14.1% patients by culture and 0.1% patients in smear preparation only. In CSOM patients, age predominated in 20-27 yrs group, sex in male below 30 yrs, and Aspergillus flavus, A. niger, Penicillium, A. fumigatus in mycelial fungus, Candida albicans, C. parapsillosis in yeast. But in 18 post antibiotic fungus infected patients Penicillium and A. niger were the important isolates. In otomycosis and otitis externa patients A. niger took the main role.

Adult↗
PubMed1988

Involution of thymic epithelium and low serum thymulin bioactivity in weanling mice subjected to severe food intake restriction or severe protein deficiency.

The volume of epithelium in the cortex and in the medulla of the thymus was compared in four groups of weanling male and female CBA/J mice. Well-nourished controls (C), food intake restricted (R), and animals given a low-protein diet ad libitum (LP) were fed from 23 to 37 days of age. Baseline controls (B) were studied at 23 days of age. Epithelial volume fraction was estimated for each group by point-counting morphometry on electron micrographs. Other mice were used to obtain group mean estimates of thymic index (mg/g live weight) and volume fraction of cortex and medulla (light microscope-level point-counting morphometry). Cortical and medullary epithelial volumes were calculated for each animal examined by electron microscopy by obtaining the live weight and applying, in sequence, the group mean thymic index, an assumed thymic density of 1.0 mm3/mg, the group mean cortical or medullary volume fraction, and the measured cortical or medullary volume fraction for that animal. Serum thymulin bioactivity was also measured in C, R, and LP mice. The results reveal thymic epithelial involution in the two most common rodent models of malnutrition, and suggest that this may contribute to the low serum thymulin levels found in malnourished experimental animals and humans.

Animals↗
PubMed1987

Human T cell proliferative responses to particulate microbial antigens are supported by populations enriched in dendritic cells.

The efficacy of dendritic cells in antigen presentation was studied in eight healthy subjects using a lymphoproliferation assay. Both particulate (Mycobacterium leprae, H37Ra) and soluble (PPD, tetanus toxoid) bacterial antigens were used as stimulants over a concentration range of accessory cells (monocytes (MO) and dendritic cells (DC)) varying from 10 to 0.1% in co-cultures using T-enriched cells. In general, co-cultures with T + MO and T + DC at all concentrations of accessory cells showed significant improvement of antigen-induced lymphoproliferation over PBMC cultures. The improvement in delta ct/min of T + DC co-cultures as compared to T + MO with parallel concentrations of accessory cells (P less than 0.05 to less than 0.01) was significant. Of the bacterial antigens used to test the antigen-presenting ability of DC, the particulate antigen (H37Ra) showed the most impressive improvement (380%) of T cell proliferation in DC reconstituted cultures as compared to monocytes. PPD, soluble protein derived from a similar tuberculosis strain of mycobacteria, was not presented as effectively as the particulate equivalent even though the donors of the appropriate cell combinations showed skin test reactivity to this antigen.

Antigens, Bacterial↗
PubMed1985

Thymic epithelial cells of severely undernourished mice: accumulation of cholesteryl esters and absence of cytoplasmic vacuoles.

The thymic epithelium was compared in weanling male and female CBA/J mice when fed ad libitum and when subjected to severe food intake restriction for 14 days. The restriction protocol elicited predominantly a metabolic response to caloric deficit rather than to protein deficiency. Electron microscopy revealed intracytoplasmic accumulations of large, circular, homogeneously electron-dense profiles (with no limiting membrane) in a high proportion of cortical and medullary epithelial cells of thymuses from restricted mice, but not from controls. The electron-dense material was not preserved in the absence of osmium. Thin-layer chromatography (TLC) indicated elevated levels of free and esterified cholesterol, particularly the latter, in whole thymus extracts of restricted mice. Measurements of total cholesterol levels in the thymic extracts were consistent with the results obtained by TLC. In addition, cryostat sections of thymuses from restricted mice, but not from controls, exhibited numerous stained foci throughout the cortex and medulla when treated with oil red O (a general neutral lipid stain) or by the Schultz procedure which is specific for cholesterol. Collectively the results suggest accumulations of cholesteryl esters, together with some free cholesterol, as non-membrane-bound droplets in the cytoplasm of thymic epithelial cells of undernourished mice. It is also of interest that the lipid-laden epithelial cells exhibited none of the cytoplasmic vacuoles observed in controls and believed to be important in thymic hormone secretion. This work provides the first direct evidence of thymus epithelial abnormalities in severe protein-energy malnutrition.

Animals↗
PubMed1983

Radiometric macrophage culture assay for rapid evaluation of antileprosy activity of rifampin.

The antileprosy effect of rifampin was evaluated by a newly developed rapid in vitro assay wherein 31 human-derived strains and 1 armadillo-derived strain of Mycobacterium leprae were maintained for 2 and 3 weeks, respectively, in murine and human macrophages in the presence of [3H]thymidine. Of these strains, 27 showed significant incorporation of the radiolabel in cultures of live bacilli as compared with control cultures of heat-killed bacilli of the same strain. Consistent and significant inhibition of [3H]thymidine uptake was observed in M. leprae resident cultures with 3 to 200 ng of rifampin per ml as compared with similar cultures without the drug. In general, an increase in percent inhibition was seen from 3 to 20 ng/ml, with marginal increases at 40, 50, and 100 ng/ml. M. leprae strains appear to be remarkably susceptible to this drug in the in vitro assay.

Animals↗
PubMed1983

Rapid, radiolabeled-microculture method that uses macrophages for in vitro evaluation of Mycobacterium leprae viability and drug susceptibility.

This paper describes a microculture rapid assay using radiolabeling and mouse macrophages to determine the viability and the drug susceptibility or resistance of Mycobacterium leprae. Comparison of M. leprae resident macrophage cultures maintained in 96-well flat-bottomed plates showed results for viability and susceptibility or resistance to dapsone that were similar to results for concurrent cultures in Leighton tubes with greater numbers of bacilli and macrophages.

Adult↗
PubMed1982

Lack of correlation between morphological index and viability as assessed by the uptake of 3H-thymidine by macrophage resident M. leprae.

Thirty strains of M. leprae derived from skin biopsies of lepromatous leprosy patients were scored for Morphological Index (MI) and concurrently maintained for 2 weeks in macrophage cultures containing 3H thymidine. Selective and significant incorporation of the radioactive label was observed in cultures containing freshly extracted M. leprae as compared to control cultures with autoclaved bacilli from the same biopsy. The percentage incorporation of 3H thymidine ranged from 103 to 1140%. Morphological Index of the bacilli from these individuals varied from zero to 8. Six cultures containing bacilli with MI of less than or equal to 1 and 3 containing bacilli with MI of zero showed significant incropration of 3H thymidine. There was no correlation between the percent of solid or beaded bacilli in the inoculum and the ability of M. leprae to incorporate 3H thymidine in the macrophage cultures.

Animals↗
PubMed1979

Studies on allergenic algae of Delhi area: botanical aspects.

To study distribution of algae in and around Delhi aerobiological surveys were undertaken for two consecutive years (September, 1972, to August, 1974). The surveys were accomplished by (a) slide exposure method and (b) culture plate exposure method. A total of 850 slides were exposed using Durham's gravity sampling device. Of these, 560 slides were exposed during 1973 (272 slides at two meter and 288 at ten meter height) and the rest (290 slides) were exposed during 1974 at ten meter height. A total of 858 culture plates were exposed (276 for one hour and 282 for two hours) during 1973 and the rest (300 culture plates) were exposed during 1974 at ten meter height for two hours duration only. Air was found to be rich in algae flora during the months of September to November. The dominant forms of algae present were all blue greens. This might be due to the relative greater resistance of blue green algae to unfavorable conditions.

Air Microbiology↗
PubMed1979

Respiratory allergy to algae: clinical aspects.

A comprehensive investigation was done to evaluate the allergenic algae in the Delhi area. Results of 4,000 skin tests performed on 400 patients suffering from naso-bronchial allergy and 300 skin tests on 30 healthy persons with 10 common algae isolated from the Dehli atmosphere are presented and compared. Positive skin reactions (1+ to 3+) to algae extracts ranged from 25.7% with Lyngbya major extract to 1.7% with Oscillatoria simplicissima extract; in healthy non-allergic volunteers there were no positive skin reactions. The Prausnitz-Küstner (PK), bronchial provocation and conjunctival tests were negative in patients with negative skin reactions; in patients with positive skin reactions PK was positive in 70.9%, bronchial provocation in 50% and conjunctival in 48.5%. Levels of total IgE in patients with naso-bronchial allergy were higher, ranging from 1,225 international units per ml to 1,550 international units per ml, while in healthy volunteers the values were less than 885 international units per ml.

Allergens↗