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A N Chakrabarty

Publications and source records attributed to A N Chakrabarty.

106 records · Page 6Linked to original sources
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In vitro biological activity of prenylflavanones.

The biological activity of ten prenylflavanones purified from Sophora tomentosa L., and Sophora moorcroftiana Benth. ex Baker (Leguminosae) was investigated. The flavanones with prenyl-, lavandulyl- or geranyl groups on A ring, and two bioactive flavonostilbenes on ring B and stilbene (resveratrol) showed tumor-specific cytotoxic activity, antimicrobial activity, and anti-HIV activity, radical generation, and O2- scavenging activity. There was a positive relationship between radical generation and O2- scavenging activity in these prenylflavanones. These data suggest the medicinal significance of prenylflavanones.

Anti-HIV Agents↗
PubMedDate not supplied

Antimicrobial activity of prenylflavanones.

Among two flavanones [YS01, YS02] and eight prenylflavanones [YS03-YS10], preliminary screening with fifteen test bacterial strains showed that YS06 was the most active agent. YS06 exhibited highly significant antimicrobial action when tested against 228 bacterial strains comprising two Gram-positive and six Gram-negative genera. The in vitro susceptibility test was carried out by determining the minimum inhibitory concentration (MIC) of YS06 by agar dilution technique. Twenty-two out of fifty strains of Staphylococcus aureus were inhibited at 25 to 50 micrograms/mL of the agent. YS06 also inhibited strains of Salmonella, Shigella and a few strains of Escherichia coli strains were also highly sensitive to YS06, while Kleibsiella spp. and Pseudomonas aeruginosa were much less sensitive. In in vivo study, YS06 offered significant protection (p < 0.001 according to chi-square test) to Swiss albino mice (challenged with 50 minimum lethal dose (MLD, virulent bacterium) at concentrations of 160 and 80 micrograms/mouse.

Anti-Bacterial Agents↗
PubMedDate not supplied

Is soil an alternative source of leprosy infection?

Leprosy is believed to be transmitted only through human contacts. However, many anomalous observations had gradually accumulated which had weakened such beliefs. These are: only 1/3 rd cases of leprosy give a definite history of being transmitted from other known cases; life-long spouses, in whom only one has leprosy, seldom lead to leprosy to others; while MDT applied intensively in most leprosy endemic countries, could successfully reduce incidence of leprosy, however, simultaneously new cases arise unabated. Besides, a close look at animal leprosies also suggested a mode of transmission other than human-type contact. Thus, a search for alternative hypothesis led to the findings that leprosy bacillus (LB) could be a soil chemoautotroph and could facultatively live both in the human body and the soil which could serve as an alternative source of infection. Evaluation of accumulated evidences points to this possibility.

Adult↗
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Leprosy-derived chemoautotrophic nocardioform (CAN) bacteria closely resemble, or are identical with, Mycobacterium leprae on mycolate and other lipid profiles.

On the basis of thin layer chromatography and gas-chromatography-mass spectrometric studies, the lipid profiles of all the chemoautotrophic nocardioform (CAN) bacteria derived from human and animal leprosy tissues appear to be identical with each other, and closest to or identical with the most probable profile of M. leprae.

Actinomycetales↗
PubMedDate not supplied

In vitro and in vivo antimycobacterial activity of an antihypertensive agent methyl-L-DOPA.

Methyl-L-DOPA, an antihypertensive agent, has significant in vitro activity against a variety of atypical mycobacteria such as the Mycobacterium avium complex, M. scrofulaceum, M. xenopi and M. marinum, and rare pathogens like M. fortuitum. In the present investigation, the screening of the in vitro activity was further extended by testing the in vitro activity against a total of 53 different strains of mycobacteria, including 34 clinical isolates of both drug-sensitive and drug-resistant Mycobacterium tuberculosis. Most of the strains were inhibited at 10-25 microg/mL concentrations of the drug. When methyl-L-DOPA was injected into male mice at a concentration of 10 microg/g body weight (20 g each), methyl-L-DOPA significantly protected them when challenged with a 50 median lethal dose of M. tuberculosis H37Rv102. According to the chi2 test, the in vivo data were highly significant (p<0.01).

Animals↗
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Pronounced inhibitory effect of chlorcyclizine (CCZ) in experimental hepatocarcinoma.

Thepiperazine chlorcyclizine HCl (CCZ), possessing significant antimetabolic as well as virucidal and virustatic activities against the human immunodeficiency virus (HIV) and other retroviruses, was selected to determine its anticarcinogenic potential The anticancer activity of CCZ was evaluated against procarcinogen n-diethylnitrosamine (NDA)-initiated hepatocarcinogenesis, which was subsequently promoted by phenobarbital (PB) in male Sprague-Dawley rats. The anticancer efficacy of CCZ was monitored by estimating some potential markers of neoplastic and preneoplastic hepatic conditions, e.g., glutathione (GSH), glutathione-S-transferase (GST) and gamma-glutamyl transpeptidase (gammaGTP). CCZ exhibited antineoplastic activity on a long-term therapeutic basis. Furthermore, this drug restricted the exponential increase of the antioxidant markers in the hyperplastic nodule and the surrounding liver tissues in comparison with the carcinogen-controlled rats during the entire period of treatment. A decrease in the number of nodules was observed in the CCZ-treated group.

Animals↗
PubMedDate not supplied

Mouse footpad pathogenicity of leprosy derived nocardioform bacteria cultivated in vitro.

In vitro cultures of the nocardioform bacteria from leprosy-infected tissues consisted of granules and bacilli. Inoculation of these granules into mouse footpads (MFP) produced a mild, localised, inflammation for 4-6 weeks. The granules evoked typical granulomatous response in the subcutaneous tissue and showed gradual disintegration. Infiltration of muscles, connective tissue and epithelial cells by bacillary/mycelial masses was seen very frequently, and that of nerve bundles occasionally. Plenty of mycelial tufts emanated from many 'macrophage globi'. By 6-8 months, the granules disintegrated nearly completely releasing a large number of acid-fast bacilli (AFB), single layered rings of AFB, small globi and some residual mycelia. These AFB, harvested from the MFP, were similar to or indistinguishable from the bacillary preparations from the in vitro cultures and from the leprosy bacillus obtained directly from humans or as passaged into the MFP, on the basis of many criteria studied, including the 36k gene positivity.

Actinomycetales↗
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Cultivation in vitro of acid-fast nocardioform chemoautotrophic bacteria from mouse foot-pads infected with human strains of leprosy bacillus.

Four acid-fast nocardioform bacteria could be isolated and cultivated as pure cultures in vitro from mouse foot-pads (MFP), which were infected with serially passaged strains of human leprosy bacillus; the liquid mineral medium, such as paraffin urea minimal (PUM), paraffin gelatin minimal (PGM), gelatin minimal (GM), and GM agar (GMA) slants containing only simple sources of C and N were used, just like the human and the armadillo isolates of these organisms reported earlier. Morphologically, metabolically and enzymologically, these were closely related to the previous ones and were also chemoautotrophic in nature. Serologically there appears to be a heterogenicity in these isolates, i.e., some of them showing higher affinity to nocardioforms while others showing significant binding to several mycobacteria. Normal (uninfected) mouse foot-pad harvests were not found to harbour such organisms.

Animals↗
PubMedDate not supplied

Is leprosy bacillus a chemo-autotrophic nocardioform organism?

Numerous attempts at in vitro cultivation of the leprosy bacillus have all proved to be unsuccessful. Recently, we have repeatedly isolated chemo-autotrophic nocardioform (CAN) organisms in pure culture from multibacillary cases of leprosy. We find that these resemble the leprosy bacillus in many respects and suggest that the leprosy bacillus may be closer to the genus Nocardia than to Mycobacterium, and that it may be a chemo-autotroph, requiring only simple sources of carbon and nitrogen for its growth. This is in contrast to most other human pathogens, which are heterotrophs requiring complex sources of carbon and nitrogen for their growth. This could offer a possible explanation for the repeated failure at in vitro cultivation of the leprosy bacillus.

Humans↗
PubMedDate not supplied

Repeated isolation of nocardia like organisms from multibacillary cases of leprosy.

Nocardia like organisms were isolated from all the 22 multibacillary cases of leprosy, on minimal media consisting of only mineral salts and supplemented with simple C-sources (e.g., liquid paraffin, tetradecane etc.) and N-sources (e.g. ammonium salts, urea, asparagine, gelatin etc.). Complex organic substances, e.g., xanthine, tyrosine, casein, peptone, meat extract, egg proteins, serum, blood, yeast extract as well as medium 199, did not support the growth of these organisms at all. Paraffin-urea minimal (PUM), paraffin gelatin minimal (PGM) and gelatin minimal medium, as well as the agar slants of these media, selectively allowed good growth of these organisms on which these could be serially propagated continuously, and isolated as pure cultures; these were acid-fast long slender rods which were seen to arise directly from fragmented or unfragmented long, slender hyphae, forming at places mycelial tufts many of which, on ageing, sporulated abundantly. Their acid-fastness was pyridine susceptible and these were DOPA-Oxidase positive; these grew best under reduced 02 tension, at pH 7.0-8.0 and temperature about 28 degrees C. Serologically, these appeared to be sufficiently related to, each other, 2 nocardiae (N. brasiliensis and N. caviae) and some mycobacteria.

Culture Media↗