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C Biswas

Publications and source records attributed to C Biswas.

51 records · Page 3Linked to original sources
PubMed1984

Collagenase stimulation in cocultures of human fibroblasts and human tumor cells.

Cocultures of human fibroblasts with 3 different human tumor cell lines exhibited high levels of collagenase activity against type I collagen compared to individual cultures of each cell type. For LX-1 lung carcinoma cells maximum stimulation occurred at a ratio of tumor cells to fibroblasts of 0.5:1. These cocultures contained 15-50 times more collagenase activity than the sum of the individual cultures. Conditioned medium from the LX-1 cells stimulated the fibroblasts to an extent similar to that obtained in the cocultures. Conditioned medium from the fibroblasts did not stimulate the tumor cells. Thus human tumor cells secrete a factor(s) which stimulates collagenase production by human fibroblasts.

Animals↗
PubMed1984

Interactions between human tumor cells and fibroblasts stimulate hyaluronate synthesis.

Several types of tumors contain high concentrations of hyaluronate, yet isolated tumor cells in culture often produce little glycosaminoglycan. To explore the possibility that interactions between tumor cells and host fibroblasts stimulate hyaluronate synthesis, human tumor cells were grown separately from and in coculture with normal human fibroblasts. Stimulation was observed with each of the three types of tumor cells used: LX-1 lung carcinoma, DAN pancreatic carcinoma, and TRIG melanoma. The interaction between LX-1 cells and fibroblasts was studied in detail. Under serum-free conditions, cocultures of LX-1 and fibroblasts synthesized 3-fold more hyaluronate than the sum of that produced by LX-1 and fibroblast cultures grown separately. This stimulation was linear over 72 hr and hyaluronate represented 80% of the glycosaminoglycan synthesized. Maximum stimulation occurred at a ratio of fibroblasts to LX-1 cells of 1-2:1. Quantitation of unlabeled glycosaminoglycans by HPLC analysis of disaccharides generated by digestion with chondroitin ABC and AC lyases (EC 4.2.2.4 and 4.2.2.5) demonstrated that net accumulation of hyaluronate increased 2-fold and that hyaluronate represented 80% of total chondroitinase-sensitive glycosaminoglycan produced by the cocultures. The disaccharide patterns obtained showed that accumulations of chondroitin-4- and chondroitin-6-sulfates were stimulated proportionately to that of hyaluronate in these cocultures. Similar levels of stimulation due to coculture were obtained in serum-containing and serum-free media. Stimulation was not effected by addition of LX-1-conditioned medium to fibroblast cultures or by culturing LX-1 and fibroblasts under conditions where they shared the same medium but were physically separated. Cell contact between LX-1 and fibroblasts thus appears to be necessary for the stimulation of hyaluronate synthesis.

Blood↗
PubMed1983

A facile synthesis of [3 alpha-3 H]beta -sitosterol.

Direct oxidation of the parent sterol using CrO3 provided (24R)-24-ethyl-5-cholesten-3-one which on treatment with NaBT4 gave [3 alpha-3 H] (24R)-24-ethyl-5-cholesten-3 beta-ol. Purification at each stage afforded samples which were compared spectrally with the corresponding cholesterol series compounds.

Chromatography, Gas↗
PubMed1982

Collagenolytic activity of rabbit V2 carcinoma implanted in the nude mouse.

The relative contribution of host cells and tumor cells to the production of collagenase and its regulation during tumorigenesis were studied with the use of a heterologous rabbit tumor-nude mouse host system. The V2 carcinoma, a malignant neoplasm of the New Zealand White rabbit, behaved as a nonmetastasizing, noninvasive tumor when implanted and grown in the inbred Swiss albino nude mouse. The extracts from both tumors contained similar levels of collagenase. Tumor explants also released enzyme into culture medium in both cases, but the rabbit tumor produced approximately 10 times more collagenase than the nude mouse. Freeze-thawing of the explants or treatment with cycloheximide markedly inhibited the appearance of enzyme in the medium from the rabbit tumor but not from the nude mouse tumor. The relative proportions of mouse- and rabbit-derived collagenase in the nude mouse tumor extracts and culture medium were determined with the use of antibodies specific for rabbit V2 tumor and mouse bone collagenases. Approximately 70% of the nude mouse tumor enzyme was derived from the rabbit tumor, and approximately 30% was derived from the mouse host. These findings indicate that the former might represent stored enzyme carried over during tumor transplantation into the nude mouse, whereas the latter might have originated from stimulation of host cells during tumorigenesis.

Animals↗
PubMed1981

Inhibition of tumor growth, vascularization, and collagenolysis in the rabbit cornea by medroxyprogesterone.

Medroxyprogesterone, dexamethasone, or cortisone, locally applied in sustained release polymer to rabbit V2 carcinoma implanted in the rabbit cornea, blocked neovascularization and three-dimensional growth of the tumor. These hormones similarly prevented the vascular proliferative response to implants in the rabbit cornea of mouse B-16 melanoma and also the response to implants of polymer containing tumor extract with angiogenesis activity. The inhibitory responses were accompanied by considerable reduction in collagenolytic activity released into culture medium by explants of the two tumors and of the corneal region containing angiogenic hepatoma extract. Morphologic studies revealed extensive three-dimensional disruption of the compact laminated collagenous structure of the cornea by untreated V2 carcinoma. In the presence of hormone the tumor grew slowly as a noninvasive two-dimensional plaque limited to the narrow region of the insertion pocket in the cornea, with no obvious disturbance of structure elsewhere. Cortisone was much les effective than medroxyprogesterone or dexamethasone. Testosterone and estradiol had no effect on the three measured properties. The data suggest that local hormonal interference with neovascularization, collagenase production, and tumor growth can prevent neoplastic invasion and destruction of a dense collagenous connective tissue.

Animals↗
PubMed1979

Stimulation of collagenase production by collagen in mammalian cell cultures.

In this study, we investigated the possible regulatory role of collagen in collagenase production by cultured human skin fibroblasts and human and rabbit synovial cells. Addition of types I, II or III collagen in solution to the culture media markedly stimulated trypsin-activable collagenase activity in these cultures. In the human cell cultures the stimulatory effect of collagen was further enhanced by a soluble factor isolated from human monocyte culture media (Dayer, Russell and Krane, 1977). Both native and denatured forms of collagen stimulated enzyme production; their relative efficacy varied among the different types. The native form of both types I and II collagen showed a greater effect on collagenase production than the corresponding denatured form, whereas with type III collagen the denatured form was more effective.

Animals↗
PubMed1979

Hyaluronate and invasiveness of the rabbit V2 carcinoma.

We propose that hyaluronate, a major component of extracellular matrices through which cells migrate during embryonic tissue development and in regenerative processes, is also concentrated in the environment through which neoplastic cells invade local host tissues and may facilitate this process. The hyaluronate content of invasive V2 carcinoma grown in rabbit was found to be 3-4 times greater than that of the same tumor grown in the nude mouse, in which it is noninvasive. Moreover, hyaluronate concentrations were most elevated in the connective tissue interface between the tumor mass and the neighboring host tissue in the invasive rabbit tumors. The particular site of tumor implantation in the rabbit or nude mouse did not affect the concentrations of hyaluronate in either the parenchyma or the surrounding connective tissue. Similar values were obtained for neoplasms grown in muscle, which normally contains little hyaluronate, and in subcutaneous tissue, which is relatively rich in this glycosaminoglycan.

Animals↗
PubMedDate not supplied

Investigation on interaction of Achatinin, a 9-O-acetyl sialic acid-binding lectin, with lipopolysaccharide in the innate immunity of Achatina fulica snails.

Achatinin, a 9-O-acetyl sialic acid (9-O-AcSA) binding lectin, has been demonstrated to be synthesized in amoebocytes of Achatina fulica snails. This lectin was affinity-purified from Achatina amoebocytes lysate (AAL); it appeared as a single band on native polyacrylamide gel electrophoresis (PAGE) and showed 16 identical subunits of M.W. 15 kDa on sodium dodecyl sulphate (SDS)-PAGE. It was found to be homologous with an earlier reported lectin, Achatinin-H, derived from hemolymph of A. fulica snails (Sen, G., Mandal, C., 1995. The specificity of the binding site of Achatinin-H, a sialic-acid binding lectin from Achantia fulica. Carbohydr. Res., 268, 115-125). Homology between both lectins was confirmed by their similar electrophoretic mobilities, carbohydrate specificity and cross reactivity on immunodiffusion. Achatinin showed in vitro calcium dependent binding to two 9-O-acetylated sialoglyoconjugates (9-O-AcSG) on lipopolysaccharide (LPS) (Escherichia coli 055: B5) of M.W. 40 kDa and 27.5 kDa, which was abolished following de-O-acetylation. Based on the previously defined narrow sugar specificity of Achatinin towards 9-O-AcSAalpha2-->6GalNAc [Sen, G., Mandal, C., 1995. The specificity of the binding site of Achatinin-H, a sialic-acid binding lectin from Achatina fulica. Carbohydr. Res., 268, 115-125], we conclude that LPS contains this lectinogenic epitope at the terminal sugar moiety. The Achatinin-mediated hemagglutination inhibition of rabbit erythrocytes by LPS further confirmed it. The lectin exhibited bacteriostatic effect on Gram-negative bacteria E. coli, DH5alpha and C600. AAL was earlier reported to undergo coagulation in presence of pg level of LPS (Biswas, C., Mandal, C., 1999. The role of amoebocytes in the endotoxin-mediated coagulation in the innate immunity of Achatina fulica snail, Scand. J. Immunol. 49, 131-138). We now demonstrate that Achatinin participates in LPS-mediated coagulation of AAL as indicated by enhanced release of Achatinin from the LPS stimulated amoebocytes and most importantly, by exhibiting a 77% decline in the coagulation of AAL when depleted of Achatinin. Level of Achatinin sharply declined (17-fold) following injection of LPS (20 microg per snail) to the snails, which was reversible by simultaneous injection of LPS and leupeptin implying the presence of LPS-mediated serine protease activity in Achatinin. This was substantiated when purified Achatinin in vitro showed serine protease activity in the presence of LPS followed by its complete blockage in the presence of leupeptin and phenyl methyl sulphonyl fluoride. Therefore, Achatinin, an abundantly available lectin at multiple sites of A. fulica, by virtue of its interaction with LPS, essentially plays a crucial role in the innate immune protection of A. fulica snails.

Animals↗