Biomedical subjects

S Basak

Publications and source records attributed to S Basak.

At least 37 records · Page 2Linked to original sources

PubMed1998

Colorectal carcinoma invasion inhibition by CO17-1A/GA733 antigen and its murine homologue.

BACKGROUND: The gastrointestinal carcinoma antigen GA733 is a potential target for passive and active immunotherapy for patients with colorectal carcinoma. This antigen has been characterized previously as a homophilic adhesion (i.e., adhesion to self) protein, but the functional consequences of homophilic adhesion for tumor growth and invasion are unknown. The availability of a murine homologue of GA733, i.e., murine epithelial glycoprotein (mEGP), allows for functional analysis of cell adhesion as it relates to tumor growth and invasion, both in vitro and in vivo. METHODS: CT-26 murine colorectal carcinoma cells were transfected with complementary DNAs encoding either the human or the murine antigen. GA733- or mEGP-producing cells were evaluated for homophilic adhesion, growth on plastic surfaces, colony formation in soft agar, and invasion through a reconstructed basement membrane (Matrigel). mEGP-producing cells were also examined for their capacity to metastasize in mice. Reported P values are two-sided. RESULTS: Compared with control cells, mEGP-producing cells showed significantly lower growth rates, colony formation, and invasion through Matrigel in vitro (all P values <.05). Compared with vector-only transfected cells and parental cells, mEGP-producing cells showed a reduction in metastatic potential in syngeneic immunodeficient and immunocompetent mice (all P values <.05). In contrast to mEGP-transfected cells, GA733-transfected cells did not exhibit significantly reduced growth or colony formation in vitro (all P values >.05). However, GA733-transfected cells did show reduced invasion through Matrigel compared with vector-only transfected cells or parental cells (all P values <.05). CONCLUSION: The adhesion proteins GA733 and mEGP inhibit invasion of tumor cells.

Animals↗

PubMed1998

Construction and characterization of encapsidated poliovirus replicons that express biologically active murine interleukin-2.

Poliovirus genomes have been constructed in which the capsid genes have been substituted with the murine gene encoding interleukin-2 (IL-2) (referred to as replicons). One replicon contained the gene for IL-2 in place of the poliovirus capsid VP2 and VP3 genes, and a second replicon was constructed that contained the murine IL-2 substituted for the poliovirus VP3 and VP1 genes. The IL-2 genes were cloned into the replicon so as to maintain the translational reading frame with the remaining poliovirus proteins. Transfection of either replicon into cells resulted in the expression of replicon-encoded proteins and replication of replicon RNA. Using a procedure developed in this laboratory, we have encapsidated these replicons into authentic polio virions by passaging the replicons in the presence of a recombinant vaccinia virus, VVP1, which expresses the capsid precursor, P1, protein. Using a quantitative immunoassay, we determined that the majority of the IL-2 produced remained intracellular, with approximately 1%-2% released from the infected cells, and that the IL-2 was biologically active. The results of these studies demonstrate the utility of poliovirus replicons for expression of small bioactive molecules and are discussed with respect to future applications as immune adjuvants as well as potential new tumor therapies.

Animals↗

PubMed1998

Health profile of two social groups living in a squatter settlement in Calcutta.

Health and well-being of individuals largely depend on socioeconomic and environmental conditions. The low socioeconomic groups face the highest health burdens. In the present study an attempt has been made to compare and contrast the health related traits prevalent in two social groups (Hindu and Muslim), living in a squatter settlement in Calcutta, India. The study has been conducted on women between 20 to 40 years of age. The results show that the Muslims are more frequently affected with respect to most of the traits than the Hindus, but the difference is significant with respect to only a few traits. Thus, micro-cultural traits associated with religion do not seem to have much effect on the health related traits considered in this study.

Female↗

PubMed1998

Benign fibrous histiocytoma of the nasal septum.

Among the non-epithelial tumours of the nasal cavity, paranasal sinuses and nasopharynx, fibrous histiocytoma is rarely encountered. A 45 year-old male patient complaining about nasal obstruction and nasal swelling was seen in the hospital ENT department. On examination, there was a mass located on the right anterior part of the nasal septum, about 2 x 1 x 1 cm in size. The pathologic diagnosis was benign fibrous histiocytoma. In this article we discuss the clinical, radiological, histopathological characteristics of fibrous histiocytoma and its differential diagnosis.

Angiofibroma↗

PubMed1997

Human colorectal cancer (CRC) antigen CO17-1A/GA733 encoded by adenovirus inhibits growth of established CRC cells in mice.

The human colorectal carcinoma (CRC)-associated Ag CO17-1A/GA733, originally defined by mAbs CO17-1A and GA733, has been a useful target in passive immunotherapy of CRC patients with mAb and in active immunotherapy with anti-idiotypic Abs mimicking the CO17-1A or GA733 epitope. Both approaches have targeted single epitopes. We investigated the capacity of full-length CO17-1A/GA733 Ag expressing multiple potentially immunogenic epitopes and encoded by recombinant adenovirus 5 (Ad5 GA733-2) to induce humoral, cellular, and/or protective immunity in mice. Ad5 GA733-2 induced Ag-specific Abs that reacted predominantly to CO17-1A- and GA733-unrelated epitopes on the Ag and lysed Ag-positive CRC targets in conjunction with effector cells. Ad5 GA733-2-immune mice developed Ag-specific, proliferative lymphocytes of Th1 type and cytolytic lymphocytes. The use of Ad5 GA733-2 to immunize mice bearing established syngeneic CRC cells transfected with the human Ag induced significant and specific tumor regression. Cured mice resisted rechallenge with human CO17-1A/GA733 Ag-negative parental CRC cells, suggesting that targeting the human Ag on the murine transfectants induced protective immunity to other Ag expressed by the parental tumor. These results may explain the high potency of the recombinant vaccine. Thus, rAd5 GA733-2 may have potential as a vaccine for CRC patients.

Adenoviridae↗

PubMed1997

Cytotoxic T-cell clone against rectal carcinoma induced by stimulation of a patient's peripheral blood mononuclear cells with autologous cultured tumor cells.

In an effort to establish cytolytic T lymphocytes (CTLs) against colorectal carcinoma (CRC) by stimulating patients' lymphocytes with autologous tumor cells, we used peripheral blood mononuclear cells (PBMC) from a patient with minimal residual rectal carcinoma following removal of the primary lesion and involved regional lymph nodes as a source to generate CTLs in culture. A CTL line and clone were established from the patient's PBMC following stimulation of PBMC with autologous, cultured tumor cells and interleukin-2. The CTL line and the clone consisted predominantly of CD4+ lymphocytes. The CTL clone expressed two T-cell receptor variable alpha chains (V alpha11 and V alpha22) and one beta chain (Vbeta14). The cytokine secretion pattern of the CTL line was of the Th1-type. Both the CTL line and the clone lysed the autologous rectal carcinoma cells, but not the allogeneic, partially human lymphocyte antigen (HLA)-matched or nonmatched CRC cells, autologous Epstein-Barr virus-transformed B cells, K562 (natural killer target) cells or Daudi (lymphokine-activated killer target) cells. Lysis of autologous tumor cells most likely was HLA class I-restricted. Our unique success in generating CTLs against this tumor type may rest in the inclusion of a patient with minimal residual, rather than advanced, disease.

Amino Acid Sequence↗

PubMed1997

Expression of an antigen homologous to the human CO17-1A/GA733 colon cancer antigen in animal tissues.

The CO17-1A/GA733 antigen is associated with human carcinomas and some normal epithelial tissues. This antigen has shown promise as a target in approaches to passive and active immunotherapy of colorectal cancer. The relevance of animal models for studies of immunotherapy targeting this antigen in patients is dependent on the expression of the antigen on normal animal tissues. Immunohistoperoxidase staining with polyclonal rabbit antibodies to the human antigen revealed the human homologue on normal small intestine, colon and liver of mice, rats and non-human primates, whereas mouse monoclonal antibodies to the CO17-1A or GA733 epitopes on the human antigen did not detect the antigen. Polyclonal rabbit antibodies, elicited by the murine antigen homologue derived from recombinant baculovirus-infected insect cells, immunoprecipitated the antigen from mouse small intestine, colon, stomach, kidney and lung. The isolated recombinant murine protein bound polyclonal, but not monoclonal, antibodies to the human CO17-1A/GA733 antigen, and recombinant human antigen bound polyclonal antibodies elicited by the murine antigen homologue. Thus, the antigen homologue expressed by animal tissues is similar, but not identical, to the human antigen. These results have important implications for experimental active and passive immunotherapy targeting the CO17-1A/GA733 antigen.

Animals↗

PubMed1997

Overoxidized poly(pyrrole-co-[3-(pyrrol-1-yl)-propanesulfonate])-coated platinum electrodes for selective detection of catecholamine neurotransmitters.

The cation-exchange and anion-exclusion properties of the poly¿pyrrole-co-[3-(pyrrol-1-yl)propanesulfonate]¿-(PPy-PS) copolymer are exploited for imparting higher selectivity to measurements of primary neurotransmitters in the presence of ascorbic acid. Such incorporation of ionizable sulfonated groups in the pyrrole ring prior to its electropolymerization leads to effective rejection of the anionic ascorbate species and preferential collection of the cationic dopamine and norepinephrine. Overoxidized PPy-PS films thus offer better discrimination against ascorbic acid than Nafion or overoxidized polypyrrole coatings. Experimental variables influencing the permselective behavior of the PPy-PS layer, including the electropolymerization time and solution pH, were explored. The selectivity and sensitivity improvements associated with the increased electrostatic character of overoxidized polypyrrole films hold promise for neurochemical electrochemical studies.

Animals↗

PubMed1997

Immunodiagnosis of human hydatid disease.

A study was undertaken to evaluate the efficacy of Enzyme Linked Immunosorbent Assay using locally prepared antigens for immunodiagnosis of human hydatid disease. A total of 90 cases clinically suspected to be suffering from hydatid disease and 100 controls matched for age and sex were included in the study. Two types of ELISA were performed on detected specific antihydatid antibodies belonging to IgG/IgM/IgA classes and other type detected IgE class of antibodies. Antigen prepared from the human hydatid fluid was found to be unsuitable for diagnosis as it contained host proteins i.e. IgG. Sheep hydatid fluid obtained from the fertile hydatid cyst was used to prepare and standardize the antigen. ELISA test to detect anti hydatid antibodies belonging to either IgG, IgM and or IgA was found to be highly specific (98 per cent) in surgically confirmed hydatid disease and was negative in all the controls. The results of the study indicate that ELISA along with casoni test may provide the best results in diagnosis of hydatid disease.

Adolescent↗

PubMed1996

Structural alterations of horseradish peroxidase in the presence of low concentrations of guanidinium chloride.

The presence of very low concentrations of guanidinium chloride (GdmCl) alters the tertiary structure of the monomeric heme-containing enzyme, horseradish peroxidase (HRP). The change in tertiary structure of the protein was reflected in the mean fluorescence lifetime of its single tryptophan residue, which increased from 2.3 +/- 0.1 ns in the native enzyme to 2.7 +/- 0.2 ns in the presence of 100 mM GdmCl. More convincing evidence in support of such alterations came from quenching study of tryptophan fluorescence using the most widely used quencher, acrylamide. It revealed significant differences between the Stern-Volmer quenching constants observed in the absence and in the presence of GdmCl concentrations below 100 mM. The fluorescence emission maximum of 6-propionyl-2-(dimethylamino)naphthalene (PRODAN), used as an extrinsic fluorophore to probe any changes in the tertiary structure of the enzyme, was blue-shifted from 522 nm in aqueous buffer to 509 nm in the presence of 27 microM native HRP. However, this emission maximum appeared at 519 nm when the PRODAN was incorporated in HRP previously incubated with 100 mM GdmCl. The fluorescence lifetime of PRODAN incorporated in HRP was also different from that of PRODAN in buffer, but much more so in absence of GdmCl than in its presence. Taken together, these results indicate partial unfolding of HRP leading to a conformation with native-like secondary structure and unaltered enzymatic activity, in presence of millimolar concentrations of GdmCl.

Circular Dichroism↗

PubMed1996

Inhibition of rat C6 glioblastoma tumor growth by expression of insulin-like growth factor I receptor antisense mRNA.

The expression of insulin-like growth factor I receptor (IGF-IR) antisense mRNA inhibits the growth of C6 rat glioblastoma cells both in vitro and in vivo [Cancer Res (1994) 54:2218]. Moreover, the injection of C6 cells expressing an antisense mRNA to the IGF-IR into syngeneic rats prevents subsequent wild-type tumorigenesis and induces regression of established tumors. For the study of immune function in syngeneic rats, C6 cells expressing either IGF-IR sense or IGF-IR antisense mRNA were injected and splenic lymphocyte function analyzed in vitro after 2 weeks. Cytotoxic, CD8+ lymphocytes from animals injected with IGF-IR antisense cells, but not from those treated with IGF-IR sense cells, proliferated in vitro in response to wild-type C6 cells. Wild-type C6 cells or IGF-IR-sense-RNA-expressing cells rapidly formed tumors upon subcutaneous injection into athymic nude mice. IGF-IR antisense cells were weakly tumorigenic, exhibiting a six- to tenfold increase in tumor latency. Injection of IGF-IR antisense C6 cells mildly delayed the development of wild-type tumors, and did not induce the regression of established wild-type C6 tumors in athymic nude mice. Thus, these findings demonstrate the stimulation of a cellular immune response in rats following the injection of IGF-IR antisense cells. However, studies of athymic nude mice indicate that expression of IGF-IR antisense mRNA also inhibits C6 cells tumorigenicity by additional mechanisms.

Animals↗

PubMed1996

High-dose administration of nonionic contrast media: a retrospective review.

PURPOSE: To assess the safety of high-dose nonionic contrast media (CM) during a single radiologic procedure. MATERIALS AND METHODS: From November 1991 to August 1995, 255 high-dose angiographic procedures were performed in 228 patients with normal serum creatinine (SCr) levels (< or = 1.6 mg/dL [141 mumol/L]). All patients received 250-800 mL low-osmolarity CM (300 mg iodine per milliliter). Pre- and postprocedure SCr levels were assessed. Urine output was measured daily in the 75 patients who received more than 400 mL CM. With linear regression analysis, a dose-related elevation in SCr levels was calculated. RESULTS: No patient developed abnormal SCr levels (> 1.6 mg/dL [141 mumol/L]) as a result of the CM. Among the patients who received more than 400 mL, none developed oliguria over the first 36 hours. With follow-up up to 3 years, no patient experienced delayed clinical renal failure. In 11 (4.3%) patients, the SCr levels increased more than 25%, but all increases were within expected limits (chi 2 analysis). Linear regression analysis revealed a 0.015 mg/dL (1 mumol/L) increase in SCr levels per 100 mL CM. CONCLUSION: Intravenous administration of high-dose low-osmolarity iodinated CM appears safe in patients without renal dysfunction or other underlying risk factors, in doses as large as 800 mL (300 mg iodine per milliliter).

Adolescent↗

PubMed1995

Somatostatin in a water-restricted environment: fluorescence and circular dichroism study in AOT reverse micelles.

Steady-state and time-resolved fluorescence emission from the single tryptophan residue of somatostatin, and the kinetics of quenching of this emission, were studied in aqueous solution and in reverse micelles of sodium bis (2-ethylhexyl) sulfosuccinate (AOT)/water/isooctane, a system that mimics the water-membrane interface well. Incorporation into micelles caused blue shifts and reduced band-widths of the emission peaks and altered the quantum yields with respect to emission from bulk water. Steady-state anisotropy values also increased considerably on micellization. These observations point to reduced polarity of the environment around the Trp residue of the peptide, as well as restricted freedom of its rotational motions, due to transfer from the aqueous to the micellar phase. Fluorescence emission kinetics of the Trp moiety followed biexponential decay laws in both aqueous and micellar media. Static and dynamic quenching constants were measured for acrylamide and CCI4 quenchers localized in the micellar and organic pseudophases, respectively, using both steady-state and time-resolved experiments. The efficiency of dynamic quenching by acrylamide became vanishingly small in going from water to reverse micelles, in sharp contrast to the comparable quenching efficiencies exhibited by CCI4 in micelles and acrylamide in water. The circular dichroic (CD) spectrum of the native peptide in water indicated the possibility of some amount of beta-type secondary structure being present. Conformational analysis of CD spectra in micelles showed that the relative amount of this structural feature was enhanced for the micellized peptide but was insensitive to the water content of micelles.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1995

A study of immune profile in human hydatid diseases.

A clinico haematological and immunological study was undertaken in 90 patients clinically suspected to be suffering from hydatid disease over a period of 1 year. The parameters studied included age of presentation, site of cyst localisation, haematological profile, total immunoglobins of different classes (IgG, IgM, IgA & IgE) and complement component C3, rosette forming lymphocytes, blast cell formation in response to phytohaemagglutinin (PHA-P) and concanavalin A (Con-A) and casoni test using standard methods. Twenty two out of 90 (22.44%) clinically suspected patients were surgically confirmed as hydatid disease cases. Hydatid disease occured in all age groups. Youngest case was 8 years and oldest 70 years. In 17/22 cases the cyst localised in the liver followed by lungs (3) neck (1) and kidney (1). Majority of patients (63.65%) belonged to blood group B. The mean total leucocyte and eosinophill counts were raised significantly (p < 0.001 and p < 0.05, respectively) in confirmed patients. The mean ESR value was raised in hydatid patients though, not significantly (P > 0.08). All the four classes of immunoglobulins viz. IgG, IgA, IgM, IgE and complement C3 were significantly raised in patients of hydatid disease compared to controls (P < 0.001, P < 0.002, p < 0.01 and p < 0.01, P < 0.02 respectively). The percentage of lymphocytes in peripheral blood in hydatid patients was reduced though, not significantly (P > 0.2). The absolute lymphocyte count was raised and mean percentage of T cells was reduced in patients with hydatid disease (P < 0.001 and P < 0.001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Transferable drug resistance in Salmonella typhi strains isolated from an outbreak at Calcutta in the recent past.

Transferable drug resistance, phage type, biotype and minimum inhibitory concentration to different drugs were studied in 50 Salmonella typhi strains isolated during recent outbreak of enteric fever at Calcutta. The antibiotic sensitivity test showed that 44% strains were sensitive to multiple drugs including chloramphenicol. The minimum inhibitory concentrations of the drugs tested were well above the normal level. The transferable drug resistance test suggested that all the resistant strains were carrying transferable multidrug resistant gene containing ampicillin, chloramphenicol, streptomycin, tetracycline resistance factor. From phage typing it was observed that 30% strains belonging to phage type 51, and among them 80% strains were carrying transferable drug resistant factor containing ampicillin, chloramphenicol, streptomycin and tetracycline.

Disease Outbreaks↗

PubMed1994

Identification of a 40- to 42-kDa attachment polypeptide for canine parvovirus in A72 cells.

The attachment of canine parvovirus (CPV) to different cell lines was quantitated by a fluorescence-activated cell sorter assay. The viral attachment was observed to both permissive A72 and nonpermissive ST cells but not to nonpermissive MDBK cells. The binding of and infectivity for CPV to A72 cells was reduced upon prior treatment of cells with Vibrio cholerae neuraminidase or lectins, specific for sialic acid. Similarly, treatment of cells with any of several proteases reduced virus binding; however, phospholipase treatment had no effect indicating that one or more membrane glycoproteins were involved in virus binding. These proteins were characterized with a virus overlay protein blot assay. Virus bound to a protein with a molecular mass of 40 to 42 kDa in membranes prepared from A72 and ST cells and not from MDBK cells. The binding to this polypeptide was specific since increasing amounts of unlabeled virions competitively inhibited binding of radiolabeled virions in a dose-dependent manner. A polypeptide of similar molecular mass was immunoprecipitated from radiolabeled octyl glucoside (OG) extract of A72 cells using purified virions, virion-specific antiserum, and protein A. The binding to this polypeptide was decreased but not abolished upon prior treatment of the membrane with V. cholerae neuraminidase. CPV preferentially recognized a polypeptide of similar molecular size in the OG extract prepared from the biotinylated basolateral surface of polarized MDCK monolayer. Hence, we propose that the 40- to 42-kDa glycoprotein represents a specific attachment molecule for CPV in A72 cells.

Animals↗

PubMed1993

Fluorescence study of melanocyte stimulating hormones in AOT reverse micelles.

Fluorescence emission from the single tryptophan residues of two melanocyte stimulating hormones, alpha-MSH and delta-MSH, and their quenching kinetics were studied in aqueous solution and in reverse micelles of AOT/water/isooctane. Incorporation into micelles caused blue shifted and narrower emission peaks, altered quantum yields and considerably enhanced anisotropies for both peptides when compared to emission from bulk water. The variation of emission parameters with micellar water content was interpreted to suggest that while the tryptophan in alpha-MSH lies in close vicinity of the water-AOT molecular interface, that in delta-MSH is solubilized in the central water pool. Total emission intensity decays followed complex (biexponential) kinetics in both aqueous and micellar media. Although the mean lifetimes for both peptides were always nearly the same, the average rotational correlation times in micelles for alpha-MSH were three times as much as those for delta-MSH. Stern-Volmer plots obtained using acrylamide and CCl4 as quenchers localized in the micellar and organic pseudophases, respectively, were non-linear and dependent on emission wavelength. Quenching by acrylamide was more efficient for delta-MSH than for alpha-MSH, while the opposite was true for quenching by CCl4. The implication of this result for localization of the peptides in micelles was consistent with the earlier one emerging from these studies.

Acrylamides↗

PubMed1993

Leukaemoid reaction in diarrhoeal diseases.

There was an outbreak of diarrhoea/dysentery in Naxalbari, North Bengal in August-September of 1992. Ninety-seven cases were investigated. Bacterial pathogens were isolated from stools of 17 cases and the organisms were Salmonella typhimurium (76%), Salmonella enteritidis (12%) and Shigella dysenteriae type 1(12%). A leukaemoid reaction was observed in 4 cases (24%) amongst all 17 patients and they were all children.

Adolescent↗