Biomedical subjects
Publications and source records attributed to A K Pal.
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Mining in India is still relatively unmechanized, and in the hot, humid, and noisy environment with uncomfortable postures, many work operations impose a considerable physiological strain. The physical characteristics, including aerobic capacities, of 54 workers in an Indian metalliferous mine have been studied, and their energy expenditures measured during long periods of work in different tasks. The mean VO2max was 2.32 +/- 0.6 l/min and the mean body mass was 60 +/- 4 kg. Averaged energy expenditures for different tasks ranged between 9.4 and 22.8 kJ/min and were usually more than 33% of the workers' maximal work capacity. Recommendations about reducing the stress of mining work are made.
The occurrence and accumulation of dicentric marker (dic) chromosomes with terminal centromeres have been documented in a murine ascites sarcoma cell line (S180) during in vivo progression of the tumour for many years. Initially, in 1975, the cell line had only one such "dic" but currently the predominant clone is represented by three such "dics". Moreover, the emergence of a new sub-clone with four dicentric markers has recently been recorded. The possible significance of the preferential accumulation of "dics" in the cell line is discussed.
Several nitrofurans were found to induce umu gene expression in Salmonella typhimurium TA1535/pSK1002 as defined on the basis of at least a 2-fold increase of beta-galactosidase activity over the background level. beta-Galactosidase activity increased with increasing concentrations of the chemical, attained a maximum at a concentration which was different for different nitrofurans used, and then gradually decreased with a further increase of the nitrofuran concentration. The umu gene expression test revealed that the genotoxic activity was highest for furazolidone and lowest for 5-nitro-2-furaldehyde.
Subcutaneous administration of RMI 12,936 at a dose level of 2 mg/rat on day 5 of unilaterally pregnant rat having trauma-induced decidual cell reaction (DCR) in the contralateral uterine horn, suppresses DCR, induces resorption of implanted embryos and leads to decrease in the plasma level of progesterone. Progesterone replacement (D 5-8) in this situation reverses DCR suppressive effect of RMI 12,936 but fails to prevent resorption of implanted embryos. It is concluded that possibly the drug simultaneously exerts embryotoxic as well as luteolytic effects, but these effects are independent.
One human cancer of the uterine cervix xenograft was established in tissue culture only after repeated passages in nude mice suggesting that with the repeated passages in nude mice, tumour cells acquire some properties which allow them to grow in vitro. Attempts to establish cell line tumours from earlier passages were not successful. The established cell line is tumourigenic. On inoculation of cultured cells in nude mice tumour take was found to be 100%. Karyotypic analysis revealed human origin.
Induction of differentially stained sister chromatids at G2/M and determination of baseline sister chromatid exchanges (SCEs) in ascites form of mouse sarcoma 180 cell line have been done by in vivo incorporation of 5-bromodeoxyuridine (BrdU) for two consecutive DNA replication cycles. The baseline SCE frequency is 6.24 at log phase of tumour growth.
The microstructure and growth of ZnTe films deposited onto glass and freshly cleaved NaCl substrates are carefully studied by a TEM. Effect of different stimulator on the grain growth is also described.
Repair-deficient and repair-proficient strains of E. coli K12 were sensitive to nitrofurantoin treatment to varying degrees with the double mutant strain (uvrA 6, recA 13) being most sensitive. Ultraviolet absorption data and thermal chromatography through a hydroxyapatite column revealed that nitrofurantoin treatment of V. cholerae strain OGAWA 154 produced a maximal amount of 55% reversibly bihelical DNA at a nitrofurantoin dose of 120 micrograms/ml/h, which indicated the formation of inter-strand cross-links in DNA. Nitrofurantoin also produced prophage-lambda induction in E. coli K12 strain GY 5027: envA, uvrB, ampA 1, strA (lambda), in a dose-dependent manner, the maximum induction being highly significant (P less than 0.001). Previously published mutation data coupled with the prophage induction data presented here suggest that the genotoxic properties of nitrofurantoin are mediated through the SOS pathway.
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5-Nitro-2-furylacrylic acid (5-NFA) caused dose dependent inhibition of growth of Escherichia coli K-12 strain AB 2480 (uvr-, rec-), the 37% (D37) and 10% (D10) survival doses being 1.0 microgram/ml.h and 1.75 micrograms/ml.h, respectively. Although much higher doses of drug were required to achieve comparable inhibition of growth of E. coli strain 1157 (repair proficient), significant filamentation of these cells was produced by treatment with 1.0 microgram/ml 5-NFA for 4 hr. Ultraviolet absorption data and thermal chromatography through hydroxyapatite (HAP) column revealed that 5-NFA treatment of E. coli strain AB 2480 produced more than 80% of DNA reversibly bihelical due to the formation of interstrand cross-links and the initial part of the reaction obeyed a first order relation. 5-NFA also produced dose-dependent increase of prophage induction in E. coli strain GY 5027: envA, uvrB, ampA1, strA (lambda). The implications of the action of 5-NFA on DNA in relation to the induction of 'SOS' functions and carcinogenesis were discussed.
The preparation, purification, biodistribution, blood disappearance kinetics and imaging characteristics of 99mTc-2,3-diamino propionic acid (99m-Tc-DAPA) is studied. The latter three studies were conducted on rabbits as the experimental animal and the data thus obtained were compared with 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) and 131I-orthoiodohippurate (131I-OIH) with a view to find a possible replacement of the latter radiopharmaceutical with a more convenient 99mTc based compound. Preliminary data indicates favourable results for 99mTc-2,3-diamino propionic acid which warrants further investigation.
In mouse, oral administration of the benzene extract of Hibiscus rosa-sinensis flowers at a dose level of 1 gm/kg body weight/day from day 5-8 of gestation led to termination of pregnancy in about 92% of the animals. The effect was associated with a significant fall in peripheral level of progesterone and increase in uterine acid phosphatase activity, as measured on day 10. The ovary exhibited signs of luteolysis, and the corpus luteal delta 5-3 beta -hydroxysteroid dehydrogenase activity decreased markedly. The interceptive effect of the extract was prevented completely by exogenous progesterone (1 mg/mouse/day) or chorionic gonadotropin (1 I.U./mouse/day) and partially (62.5%) by exogenous prolactin (500 micrograms/mouse/day). In unilaterally pregnant mouse having trauma-induced deciduomata in the sterile horn, the extract caused resorption of the fetuses, and regression of the deciduomata accompanied by reduction in weight of the ovaries. Luteolysis, may be due to interference with the luteotropic influence, and a consequent fall in plasma level of progesterone have been suggested as the plausible cause of termination of pregnancy.
Aristolic acid (AA), obtained from Aristolochia indica Linn, disrupted nidation in mice when administered on Day 1 of pregnancy. The implantation inhibiting effect of the compound was assessed with respect to certain parameters which are characteristics of early pregnancy, such as tubal transport of ova into the uterus, hyperpermeability of the endometrial capillaries, increase in uterine weight and total protein content, endometrial bed preparation and changes in uterine phosphatase enzymes during Days 4-6 of pregnancy. The compound did not affect tubal transport of eggs, but the uterine blue reaction, caused by extravasation of the dye, pontamine blue, at future implantation sites was inhibited significantly in treated mice. Histological picture of the uterus revealed AA-induced impairment of development (i.e. decidualization) and reconciled with decreases found in uterine weight and its total protein contents in treated animals. In control untreated mice, specific uterine alkaline phosphatase (ALP) activity increased significantly from Days 4 through 6 of pregnancy, but this was prevented in treated mice. On the other hand, specific uterine acid phosphatase (AP) activity was high on Day 5, while in treated mice uterine AP activity remained low during Days 4 and 5 and increased significantly thereafter. It was inferred that AA interferes with steroidal conditioning of the uterus and renders it hostile to ovum implantation.
Benzene extractives of Hibiscus rosa-sinensis flowers, administered during day 1-4 of gestation, exerted anti-implantation effect without affecting the tubal transport of zygote. On day 4, normal number of blastocyst was present in the uterus but they did not implant. However, as studied by pontamine blue reaction, it was evident that hyper-permeability of the endometrial capillaries which is the earliest known response of a receptive endometrium to any kind of deciduogenic stimulus was inhibited by the extract. The magnitude of decidualization, as assessed by weight of the traumatized uterine horn and supported by the histological pictures of the uteri was significantly lower in comparison to that of the controls. Ovarian structure exhibited signs of luteolysis. Inadequate progestational development of the endometrium due to interference with the conditioning of the uterus with progesterone during prenidatory phase of pregnancy has been suggested as the plausible cause of the extract-induced implantation failure.
In mouse, the benzene extract of Hibiscus rosa-senensis flowers was administered at four different dose levels (250-1000 mg/kg body weight/day) from day 1-4 postcoitus. Anti-implantation response and associated changes in the uterine chemical composition were studied. With an increase in the dosage of the extract, the percentage of implantation failure increased. At the dose level of 1 gm/kg body weight, the extract led to failure of implantation in 93% of the mice. The effect was accompanied by adversely altered uterine weight, its protein content and alkaline and acid phosphatase activity. In another experiment, influence of the extract on uterine uptake of progesterone was studied in bilaterally ovariectomized mice treated with or without estrogen. It exerted neither inhibitory nor stimulatory influence on uterine progesterone uptake in untreated castrated mice but the estrogen-induced increase in the uptake level was significantly inhibited by the extract. Failure of uterine bed preparation due to antiestrogenic potentiality of the extract has been discussed as the plausible cause of implantation failure.
Chromosome studies of Dalton's lymphoma, which was originally developed in the DBA/2 mouse and later adapted to a close inbred strain of the Swiss albino mouse, revealed only one rb-marker in all cells bearing a modal number (71). After several successive in vivo passages of the tumor, a new cell clone appeared with a different modal number (70) and two rb-markers. This new cell clone gradually outnumbered the stem cells and an apparent enhancement in tumorigenicity was noted. C-banding of the new cell clone revealed that one of the two telomeric heterochromatin-bearing chromosomes, originally present in the stem cells, had been involved in a Robertsonian fusion to form the additional marker chromosome. G-banded analysis indicated the noninvolvement of chromosome #15 in the fusion.