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Biomedical subjects

S Das

Publications and source records attributed to S Das.

At least 559 records · Page 31Linked to original sources
PubMed1988

A study on the effect of vitamin A deficiency and supplementation on tumorigenesis in mice.

The effect of vitamin A deficiency and supplementation on the incidence of tumors, tumor growth and life expectancy was assessed in a murine model. Although the nature of response varied with respect to the tumor types studied, in general an increase in incidence of tumor take and further growth was noted with a concomitant fall in the survival rates in the group maintained on a vitamin A deficient diet. Supplemental vitamin A produced a prolongation of the latent period and delayed appearance of the tumor, reduced incidence and growth and improved life expectancy. Such effects seem to be mediated by a direct action of the vitamin on tumor cells, as well as through the host immune system, as revealed by nucleic acid synthetic patterns and nature of changes in the lymphocyte/neutrophil ratio, thymus weight and PHA-induced blastogenesis of peripheral lymphocytes.

Animals↗
PubMed1987

Encystation and expression of cyst antigens by Giardia lamblia in vitro.

The cyst form of Giardia lamblia is responsible for transmission of giardiasis, a common waterborne intestinal disease. In these studies, encystation of Giardia lamblia in vitro was demonstrated by morphologic, immunologic, and biochemical criteria. In the suckling mouse model, the jejunum was shown to be a major site of encystation of the parasite. Small intestinal factors were therefore tested as stimuli of encystation. An antiserum that reacted with cysts, but not with cultured trophozoites was raised in rabbits and used as a sensitive probe for differentiation in vitro. Cultured trophozoites that were exposed to bile salts showed a more than 20-fold increase in the number of oval, refractile cells that reacted strongly with anticyst antibodies, and in the expression of major cyst antigens. Exposure to primary bile salts resulted in higher levels of encystation than exposure to secondary bile salts. These studies will aid in understanding the differentiation of an important protozoan pathogen.

Animals↗
PubMed1987

Inhibition of [3H][3-MeHis2]thyrotropin releasing hormone recognition sites in the rat brain by tifluadom, a kappa opiate receptor agonist.

The effect of tifluadom (TIF), a postulated kappa-opiate agonist with a benzodiazepine (Bz) structure, on the binding of [3H][3-MeHis2]thyrotropin releasing hormone [( 3H]MeTRH) to receptors for thyrotropin releasing hormone (TRH) in membranes from rat brain was determined. Tifluadom inhibited the binding of [3H]MeTRH with an IC50 value of 1.88 microM. When the binding was carried out in the presence of an IC20 concentration of tifluadom, the Bmax value of [3H]MeTRH was decreased by 20% but no change in the Kd value was noted, indicating that the inhibition was apparently noncompetitive. Ro 15-1788 a benzodiazepine antagonist, as well as bicuculline, a gamma-aminobutyric acid (GABA) antagonist did not antagonize the effect of tifluadom on the binding of [3H]MeTRH suggesting that the benzodiazepine receptors are not involved in the action of tifluadom. Since tifluadom is suggested to be a kappa-opioid agonist, the effect of other kappa-opiate ligands were also tested for their ability to affect TRH receptors. The drugs used were ethylketocyclazocine, dynorphin(1-13) and 5-bromo-6-(2-imidazoline-2-ylamino)quinoxaline (U-50,488H). The order of potency of these compounds to inhibit the binding of [3H]MeTRH to membrane from the rat brain was in the following order: tifluadom greater than U-50,488H greater than dynorphin-(1-13) greater than ethylketocyclazocine. It is concluded that tifluadom inhibits the binding of [3H]MeTRH to receptors in brain in a noncompetitive manner. The effect does not appear to be mediated through benzodiazepine receptors but possibly through kappa-opiate receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1987

Activation of lymphocytes of normal and tumor bearing mice by mangiferin, a naturally occurring glucosylxanthone.

Mangiferin, a naturally occurring glucosylxanthone, was assessed for its immunomodulatory potential. The phytochemical induced extensive in vitro proliferation of murine splenocytes and thymocytes at the doses of 5-40 micrograms ml-1. Suppression of the proliferative response of the cells was observed with higher doses of mangiferin. Mangiferin also activated the splenocytes of tumor hosts at early and late stages of tumor growth. The Phytohemagglutinin (PHA) and Con A unresponsive splenocytes of advanced tumor bearer proliferated extensively in response to mangiferin. Mangiferin when used with Con A produced additive stimulatory effect and induced heightened DNA synthesis of normal and advanced tumor bearers' splenocytes.

Adjuvants, Immunologic↗
PubMed1987

Multiple opiate receptors and pharmacological response to morphine in rats maintained on diets differing in protein concentration.

1. The influence of diets differing in protein concentration on the characteristics of mu, delta, and kappa-opiate receptors and on the analgesic and hyperthermic responses to morphine was examined in rats. Three groups of male Sprague-Dawley rats were maintained for four weeks on isocaloric diet containing either 4, 20 or 50% protein. 2. The animals maintained on 4% protein diet weighed 92 +/- 2% of the initial weight at the end of the fourth week, whereas animals maintained on 20% and 50% protein diet weighed 222 +/- 2% and 221 +/- 2%, respectively. The average food intake per 100 g body weight on day 1 of the study in 4, 20 and 50% protein diet group was 5.0 +/- 2.2 g, 10.4 +/- 1.4 g, and 10.0 +/- 1.2 g, respectively. This difference in food intake was not observed during rest of the period of the study. 3. Water intake was higher for the animals maintained on diet containing 50% protein as compared to the other two groups. 4. The analgesic and the hyperthermic response to morphine varied in direct relation to the concentration of protein in the diet. The concentration of morphine in the brain and plasma of animals maintained on the three diets following challenge dose of morphine did not differ. Similarly the Bmax and Kd values for the binding of [3H]naltrexone, [3H]D-Ser2-Thr6-leucine enkephalin and [3H]ethylketocyclazocine to brain membranes prepared from rats kept on 4, 20 and 50% protein concentration did not differ. 5. It is concluded that the diet differing in protein concentration can alter the responses to morphine, and that such altered effects can not be accounted for by the changes in the distribution of morphine in brain and plasma or to the changes in the characteristics of the mu, delta and kappa opiate receptors in the brain.

Analgesics↗
PubMed1987

Unidirectional interaction between thyrotropin releasing hormone and opiates at the level of their brain receptors.

The effect of TRH and its analogs, MK771 and RX-77368 on the binding of [3H]D-serine-6-threonine-leucine enkephalin (delta opiate receptors), [3H]ethylketocyclazocine (kappa receptors) and [3H]naltrexone (mu receptors) to the rat brain membranes was determined. Neither TRH nor its analogs affected the binding of ligands for mu, delta, and kappa opiate receptors at either 35 or 0 degrees C. Since previous studies from this laboratory indicate that the drugs acting at the kappa, and delta opiate receptors inhibit the binding of [3H](3-MeHis2) TRH to brain TRH receptors, the present studies suggest a unidirectional interaction between opiates and TRH in the brain at the level of their receptors.

Animals↗
PubMed1987

Dorsal lumbotomy for surgery of the upper urinary tract.

Between July 1978 and December 1985, 100 patients underwent an operation on the kidneys and ureter through the dorsal lumbotomy approach. A total of 12 patients underwent dismembered pyeloplasty for ureteropelvic junction obstruction. Compared to patients who underwent an operation via the standard flank incision, these 12 patients had significantly shorter hospitalization and fewer doses of analgesics. The treatment demonstrated improved cost-effectiveness. Similar advantages were noted in the remaining patients in whom removal of calculi (78), open renal biopsy (5), simple nephrectomy (4) and removal of a foreign body in the ureter (1) were done through the dorsal lumbotomy approach. We appeal for a renaissance of the dorsal lumbotomy approach in urological teaching and practice.

Adult↗
PubMed1987

Partial purification and characterization of Naegleria fowleri beta-glucosidase.

Naegleria fowleri cells, grown axenically, contain high levels of beta-D-glucosidase which catalyzes the hydrolysis of 4-methylumbelliferyl-beta-D-glucopyranoside (4MUGlc) (Km, 0.9 mM), octyl-beta-D-glucoside (Km, 0.17 mM), and p-nitrophenyl-beta-D-glucopyranoside at relative rates of 1.00, 2.88, and 1.16, respectively (substrate concentration, 3.0 mM). When the amebae are subjected to freeze-thawing, sonication, and centrifugation (100,000 g, 1 h), 85% of the beta-glucosidase activity appears in the supernatant fraction. The beta-glucosidase was purified 40-fold (34% yield) using a combination of chromatographic steps involving DE-52 cellulose, concanavalin A-Sepharose, and hydroxylapatite followed by isoelectric focusing. The predominant soluble beta-D-galactosidase activity in the Naegleria extract copurifies with the beta-D-glucosidase; the two activities have the same isoelectric point (pI, 6.9), similar heat stabilities, are both inhibited by lactobionic acid (Ki, 0.40 mM), and exhibit optima at pH 4.5, indicating that they are probably the same enzyme. The Naegleria beta-D-glucosidase has an apparent molecular weight of 66,000, a Stokes radius of 25 A, and a sedimentation coefficient of 4.2S. The beta-glucosidase is not inhibited by conduritol beta-epoxide or galactosylsphingosine but is completely inhibited by 1.25 mM bromo conduritol beta-epoxide. The latter compound, when present in the growth medium, inhibits the growth of the organism and profoundly alters its ultrastructure, the main effect being the apparent inhibition of cytokinesis and the generation of multinucleate cells. The issue of the role of the beta-glucosidase in the metabolism of the ameba and its possible role in pathogenic mechanisms are discussed.

Amoeba↗
PubMed1987

Role of vitamin A in prevention and treatment of sarcoma 180 in mice.

The effect of deficiency of vitamin A and its supplementation on growth of murine sarcoma 180 was evaluated. The efficacy of cyclophosphamide under depleted and supplemented condition of the vitamin was also scrutinized. Supplemental vitamin A helped to check progression of tumour growth and also increased the effectiveness of chemotherapy. The action is possibly mediated through the host immune system.

Animals↗
PubMed1987

Sturge-Weber-Dimitri disease without facial nevus.

A patient with Sturge-Weber-Dimitri disease presented with intractable seizures and progressive intellectual deterioration. There was no facial nevus or focal neurologic abnormality. CT disclosed bilateral calcification in a parieto-occipital gyral pattern. Histopathology of the brain revealed extensive calcification of vessel wall in parieto-occipital cortices.

Angiomatosis↗
PubMed1987

Preoperative radiation therapy in the treatment of bladder cancer.

The authors review the role of preoperative radiation therapy in the management of patients undergoing cystectomy and the early results of a prospective randomized clinical trial comparing preoperative radiation and radical cystectomy to radical cystectomy alone. It is concluded that the coupling of preoperative radiation therapy with cystectomy has added little to our treatment of bladder cancer.

Carcinoma, Transitional Cell↗
PubMed1987

Quantification of polyethylene glycol precipitable circulating immune complex from carcinoma of cervix patients.

Changes in the level of circulating immune complexes (CIC) among Indian patients with untreated and treated squamous cell carcinoma of cervix and its correlation with the progression of the disease were studied. The quantitative determination of CIC was performed by precipitating the complex with 3% polyethylene glycol (PEG) and assaying the total protein content in the precipitate. The CIC level in serum was observed to increase gradually with the progression of the disease in CaCx and in stage III of the disease the CIC content was found to be more than double of the level obtained in normal healthy individual. The augmented CIC level in patients was found to reduce to normal levels after an interval of 104 weeks of surgery and 16 weeks of radiotherapy.

Adult↗