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Biomedical subjects

S Ramakrishnan

Publications and source records attributed to S Ramakrishnan.

At least 181 records · Page 10Linked to original sources
PubMed1991

Iniencephaly with cyclopis (a case report).

Iniencephaly is a rare neural tube defect. We report a rare association of iniencephaly with cyclopia, probably the third such report in the literature.

Abnormalities, Severe Teratoid↗
PubMed1990

Use of immunotoxins in combination to inhibit clonogenic growth of human breast carcinoma cells.

Substantial heterogeneity has been observed in the expression of individual antigens within tumor cell populations. Immunotoxins which bind to different cell surface antigens might exert additive or synergistic cytotoxicity when used in combination to eliminate all clonogenic cells within a tumor. Immunotoxins have been prepared by conjugating recombinantly derived toxin A chain to different monoclonal reagents which recognize cell surface determinants of Mr 42,000 (317G5), 55,000 (260F9), and 200,000 (741F8). Each immunotoxin was evaluated for binding, internalization, and cytotoxicity with four breast cancer cell lines. Each of the three immunotoxins bound to the SKBr3 cell line and exerted antitumor activity in a limiting dilution clonogenic assay. Simultaneous treatment with two immunotoxins produced additive antitumor activity with each of the possible combinations. Additive binding could be demonstrated by immunofluorescent techniques, however, with only one of three combinations. With two of the three combinations, subpopulations of tumor cells could be identified which lacked one or the other antigenic determinant but not both. Consequently, log-additive antitumor activity was produced by immunotoxins in combination, and heterogeneity of antigenic targets may have contributed to the combined cytotoxicity in some but not all cases.

Antibodies, Monoclonal↗
PubMed1990

Pattern of rheumatic diseases in south India. V. Ankylosing spondylitis. A clinical and radiological study.

One hundred and two patients from South India with primary ankylosing spondylitis (AS) were analysed clinically and radiologically. The mean age of onset was 26 years, with a male to female ratio of 16:1. Eleven patients presented as juvenile ankylosing spondylitis. The mode of presentation of AS included axial involvement in 59, peripheral arthritis in 38, heel pain in 18 and acute anterior uveitis (AAU) in 11. The overall incidence of extra axial features was high (90 patients). These included subjects with peripheral arthritis (49), heel pain (35), AAU (14), rib pain (11), aortic regurgitation (8), apical pulmonary fibrosis (5), mitral regurgitation (2) and conduction defects (2). Peripheral arthritis was characteristically asymmetrical and oligo articular, and involved lower limb joints. No renal involvement was noticed. Radiologically, bilateral sacroilitis was seen in 80% of cases.

Adolescent↗
PubMed1990

Cholesterol in serum, liver and small intestine under different dietary compositions.

Decrease in serum total cholesterol was noted in albino rats fed with low protein diet. Decrease was also noted in the tissues like liver, duodenum, jejunum and ileum in high protein diet, and jejunum and ileum in low protein diet. There was an increase of serum free cholesterol in low protein diet. All the tissues studied had less free cholesterol in high protein diet. Jejunum showed a decrease in low protein diet also. Serum total cholesterol increased in high fat diet. Free cholesterol increased in both the cases. Tissue total cholesterol was raised in low and high fat diets in liver, duodenum, jejunum and ileum. Free cholesterol was raised in duodenum and ileum in both high and low fat diets while that of liver and jejunum was increased only in low fat group.

Animals↗
PubMed1990

Elimination of malignant clonogenic T cells from human bone marrow using chemoimmunoseparation with 2'-deoxycoformycin, deoxyadenosine and an immunotoxin.

Autologous bone marrow transplantation may contribute to the treatment of several types of lymphoreticular malignancies. Recent studies have suggested that a combination of chemoseparation and immunoseparation may be more effective than either modality alone in eliminating malignant cells from human bone marrow. In this report an immunotoxin has been prepared by conjugating pokeweed antiviral protein (PAP) to the 3A1 murine monoclonal antibody that recognizes a 40 kD (CD7) determinant expressed by most T cell acute lymphoblastic leukemias and a majority of normal mature peripheral T cells. When HSB-2 T lymphoma cells were mixed with normal human bone marrow and incubated with 3A1-PAP and 100 microM chloroquine, approximately 3 logs of clonogenic T cells could be eliminated from a 20-fold excess of bone marrow. Treatment of cell mixtures with 2'deoxycoformycin (2'-dCF) and deoxyadenosine (dAdo) eliminated 2 logs of clonogenic tumor cells. The use of 3A1-PAP and chloroquine with dCF/dAdo was more effective than either single modality, eliminating up to 6 logs of HSB-2 tumor cells in optimal experiments. Anti-tumor activity of the combined treatment extended to T leukemia cells taken directly from patients. Although 3A1-PAP reduced CFU-GM by only 13% and BFU-E by 36%, the addition of 2'-dCF and dAdo was more toxic for normal marrow precursors, further reducing CFU-GM, GEMM and BFU-E as well as preventing recovery of CFU-GM in long-term bone marrow culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Antiviral Agents↗
PubMed1989

Characterization of a translation inhibitory protein from Luffa aegyptiaca.

A protein with a molecular weight of about 30,000 was purified from the seeds of Luffa aegyptiaca. This protein inhibited cell free translation at pM concentrations. In spite of functional similarity to other ribosomal inhibitory proteins, the NH2-terminal analysis did not show any significant homology. Competitive inhibition studies indicate no immunological crossreactivity between the inhibitory protein from Luffa aegyptiaca, pokeweed antiviral protein (PAP) and recombinant ricin A chain. Chemical linkage of the protein to a monoclonal antibody reactive to transferrin receptor resulted in a highly cytotoxic conjugate.

Amino Acid Sequence↗
PubMed1989

Recombinant ricin A chain conjugated to monoclonal antibodies: improved tumor cell inhibition in the presence of lysosomotropic compounds.

Recombinant ricin A chain was chemically linked to monoclonal antibodies directed toward human breast cancer cells, a human T-cell differentiation antigen, and mouse transferrin receptor. Three types of immunotoxins were prepared; in two of them the antibody was linked to recombinant ricin A chain by a disulfide bond and in the third, a nonreducible thioether bond was used. Immunotoxins containing a nonreducible linkage may have some advantage over conjugates containing a reducible linkage because of improved stability in vivo. Conjugation of recombinant ricin A chain through either the endogenous thiol group or through a derivatized amino group produced immunotoxins with comparable cytotoxicity. The thioether conjugate was 1000-fold less cytotoxic to target tumor cells than the respective disulfide-linked immunotoxin. However, addition of monensin, a monocarboxylic ionophore, greatly enhanced the cytotoxicity of the thioether-linked immunotoxin. Monensin increased the immunotoxin activity better than other lysosomotropic reagents that were tested. The increase in activity of recombinant ricin A chain-containing immunotoxins mediated by monensin argues against a role for contaminating ricin B chain in potentiation.

Antibodies, Monoclonal↗
PubMed1989

Constitutive production of macrophage colony-stimulating factor by human ovarian and breast cancer cell lines.

Many nonhematologic tumors produce growth factors that may influence cellular proliferation either by autocrine or by paracrine mechanisms. In the current study, human tumor cell lines were investigated for the constitutive production of macrophage colony-stimulating factor (M-CSF). Culture supernatants obtained from cell lines were analyzed using a radioimmunoassay and a radioreceptor assay specific for M-CSF. Among the various cell types analyzed, all the ovarian cell lines and a majority of the breast cancer cell lines secreted significant amount of an M-CSF-like factor. Treatment of mouse bone marrow cultures with culture supernatants from ovarian cancer cells stimulated the production of macrophage colonies. Analysis of total cellular RNA obtained from the ovarian cell lines by Northern blot showed multiple sizes of M-CSF transcripts with an abundance of a 4.2-kb message. The relative amount of M-CSF transcripts correlated with the level of immunoreactive material seen in the culture supernatants.

Animals↗
PubMed1989

Fibrocalculous pancreatic diabetes in the elderly.

Fibrocalculous pancreatic diabetes (FCPD) is a form of diabetes seen in tropical countries. It is secondary to chronic, calcific, non-alcoholic pancreatitis. FCPD is usually a disease of youth. This paper reports on two elderly onset cases of FCPD. Macrovascular complications are usually rare in FCPD patients. These two patients had evidence of macrovascular diseases probably due to the older age group of the patients.

Calcinosis↗