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Biomedical subjects

S Ramakrishnan

Publications and source records attributed to S Ramakrishnan.

At least 19 recordsLinked to original sources
PubMed1992

Human ovarian epithelial cancer cells cultures in vitro express both interleukin 1 alpha and beta genes.

Ascitic fluid from human ovarian cancer patients often contains a large number of leukocytes along with tumor cells. Some of the recent evidence suggests that the ascitic fluid contains factors capable of inducing the growth of ovarian cancer cells in vitro and in vivo. While these factors have not yet been completely characterized, growth factors secreted by the tumor cells could influence the tumor growth by paracrine and autocrine mechanisms. Earlier, we reported that ovarian epithelial cancer cells produce macrophage colony-stimulating factor. It appears that these tumor cells produce more than one cytokine. Identifying the various products secreted by the tumor cells would provide valuable information needed to understand the biology of ovarian cancer. In the present study, evidence is provided for the first time that five different human ovarian epithelial tumor cell lines and tumor cells isolated from the ascitic fluid of four cancer patients express interleukin (IL) 1 alpha and beta genes constitutively. Production of the lymphokine was determined by analyzing the cellular RNA for IL-1-related transcripts and by immunological assays. Ovarian cancer cells also secrete another pleiotropic cytokine, IL-6, constitutively. In many systems, IL-1 induces the expression of the IL-6 gene. To determine whether the basal levels of IL-6 production are dependent on the endogenous IL-1, neutralization studies were carried out. Addition of antibodies to IL-1 did not decrease the levels of IL-6 secreted by the cancer cell lines. These results suggest that multiple cytokines are produced by ovarian cancer cells and that the endogenous IL-1 may not be directly involved in the regulation of IL-6 gene expression in these cells.

Ascitic Fluid↗
PubMed1992

Serum levels of macrophage colony-stimulating factor in patients with ovarian cancer undergoing second-look laparotomy.

OBJECTIVE: The purpose of this study was to evaluate the prognostic significance of macrophage colony-stimulating factor serum levels in patients with ovarian cancer undergoing second-look laparotomy. STUDY DESIGN: The presurgical serum levels of macrophage colony-stimulating factor from 33 consecutive patients with ovarian cancer undergoing second-look laparotomy were determined and compared with those of 50 healthy control subjects. Mean differences in groups were evaluated with the Student t test. RESULTS: Sixteen of 33 patients had a positive result at second look and a mean serum macrophage colony-stimulating factor level of 2.31 +/- 1.45 ng/ml. Seventeen of 33 patients had a negative result at second look and a mean macrophage colony-stimulating factor level of 1.90 +/- 0.86 ng/ml (p greater than 0.05). The mean macrophage colony-stimulating factor level in the control group was 1.20 +/- 0.51 ng/ml. This was statistically lower than the mean level found in patients with a negative second-look result (p less than 0.05). CONCLUSION: Regardless of tumor status, serum macrophage colony-stimulating factor levels tend to be elevated at the time of second-look laparotomy.

Adult↗
PubMed1992

Stage I seminoma of the testis: is post-orchidectomy surveillance a safe alternative to routine postoperative radiotherapy?

Experience with the management of 128 patients with Stage I testicular seminoma over a 10-year period, 1980-1989, is presented. Fifty-six patients were treated with post-orchidectomy radiation therapy and 72 patients were put on surveillance. Patients thought to be at higher risk of relapse were generally treated with radiotherapy. There have been no tumour related deaths in this series; 5.4% of the irradiated group and 18% of patients on surveillance have relapsed to date. All relapses have been salvaged with further therapy and are currently in complete remission. In this interim analysis, surveillance appears to be a safe alternative to adjuvant radiation therapy provided regular, prolonged follow-up can be ensured. Surveillance is, however, time consuming and resource demanding, and should be undertaken only as part of a formal clinical study. Adjuvant post-orchidectomy radiotherapy should be considered the treatment of choice until further long-term data are available.

Adult↗
PubMed1992

High-level expression and simplified purification of recombinant ricin A chain.

Ricin toxin is a glycoprotein which catalytically inactivates eukaryotic ribosomes by depurination of a single adenosine residue from the 28S ribosomal RNA. The enzymatic activity is present in the A chain of the toxin molecule, whereas the B chain contains two binding sites for galactose. Since it is highly potent in inhibiting protein synthesis, the A chain is used to prepare cytotoxic conjugates effective against tumor cells. Such chimeric proteins are highly selective and have a wide range of clinical applications. Extensive preclinical studies on these conjugates require large amounts of purified A chain. Native ricin A chain is heterogeneous, since plants produce a number of isoforms of ricin toxin. Purified, native preparations often contain two types of ricin A chain which differ in the extent of glycosylation. By cloning and expressing the gene of A chain, one could obtain homogeneous toxin molecules devoid of carbohydrates. In addition, structural changes in the toxin polypeptide could be introduced by in vitro mutagenesis, which can improve the pharmacological properties and antitumor activity. Earlier methods of expression strategies using Escherichia coli have yielded only moderate levels of expression. In the present study, the coding region of ricin A chain was cloned into pET3b, a high-level expression vector under the control of the T7 promoter. Recombinant ricin A chain produced by this construct has an additional 14 amino acid residues at the NH2 terminus. Subsequently, a NdeI site was created at the 5' end of the gene by oligonucleotide-directed mutagenesis. The modified fragment was then introduced into pET3b vector to produce toxin polypeptide identical to the native sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Saccharomyces cerevisiae cells secreting an Aspergillus niger beta-galactosidase grow on whey permeate.

We describe the construction of a lactose-utilizing Saccharomyces cerevisiae that expresses the cDNA for a secreted, thermostable beta-galactosidase (lacA) from Aspergillus niger. Yeast cells expressing the lacA gene from the yeast ADH1 promotor on a multicopy plasmid secrete up to 40% of the total beta-galactosidase activity into the growth medium. The secreted product is extensively N-glycosylated, and cells expressing the lacA gene grow on whey permeate (4% w/v lactose) with a doubling time of 1.6 hours. Such strains may offer a solution to the increasing problem of waste whey disposal.

Alcohol Dehydrogenase↗
PubMed1992

Effect of antimicrobials on cholesterol synthesis and content in liver and small intestines.

The antimicrobials tetracycline, ampicillin and bactrim (cotrimoxazole) decreased HMG CoA reductase activity in liver and small intestines of albino rats. Diminished incorporation of 1, 2, 14C acetate into cholesterol of small intestines in bactrim group was noted. There was a significant fall in cholesterol content of liver, duodenum, jejunum and ileum of the bactrim group and jejunum only in tetracycline group.

Ampicillin↗
PubMed1991

[3H]morphine binding is enhanced by IL-1-stimulated thymocyte proliferation.

Mouse thymocytes incubated in vitro with increasing concentrations of interleukin-1 (IL-1) in the presence of phytohemagglutinin (PHA) exhibited a dose-dependent increase in cell proliferation, as measured by [3H]thymidine incorporation. Under these conditions, there was a parallel dose-dependent increase in specific [3H]morphine binding, with a maximum increase of approximately 5-fold over basal levels. The binding sites differ from classical opioid receptors in that they are not stereo-selective. Interleukin-2 was ineffective in promoting either cell proliferation or enhanced opioid binding, but the effects of IL-1 could be mimicked by phorbol myristate acetate (PMA), suggesting the involvement of tyrosine phosphorylation. These results indicate that morphine-binding sites on immune cells can be regulated by cytokine activation.

Animals↗
PubMed1991

Development of two new monoclonal antibodies reactive to a surface antigen present on human ovarian epithelial cancer cells.

Monoclonal antibodies which bind selectively to cancer cells are currently used for tumor localization and for targeting cytotoxic reagents. The success of these approaches depends on the specificity of the antibody and its reactivity to a majority of the tumor samples. Frequently, monoclonal antibodies are generated by immunizing mice with antigenic preparations from a single tumor cell line. Antibodies generated under these conditions often react to a narrow range of tumors. In the present study, mice were immunized with multiple ovarian cancer cell lines in a sequential manner to amplify the immune response against common antigenic determinants expressed in these cell lines. Spleen cells from the immunized mice were then fused with NS-1 myeloma cells to establish hybridomas. Two cell lines were selected on the basis of their selective reactivity to ovarian cancer cells after extensive screening. Monoclonal antibodies OVX1 and OVX2 bound to all 5 ovarian carcinoma cell lines tested and did not bind to normal fibroblast cells. These antibodies recognized a unique antigenic determinant present in ovarian and breast cancer cells. Cross-blocking studies showed that the binding of OVX1 and OVX2 is not displaceable by 10 other previously described anti-ovarian antibodies including OC125. In immunocytochemical studies, OVX1 reacted to a majority of ovarian cancer tissues (17 of 20) and did not bind to normal ovarian tissues. Preliminary results indicate that OVX1 and OVX2 antibodies are directed to a high molecular weight antigen. These antibodies could be used in the preparation of cytotoxic conjugates.

Animals↗
PubMed1991

Peritoneal fluid and plasma levels of human macrophage colony-stimulating factor in relation to peritoneal fluid macrophage content.

The peritoneal fluid (PF) of women with infertility (especially in the presence of endometriosis) contains increased numbers of leukocytes, 90% to 95% of which are macrophages. The high numbers of peritoneal macrophages presumably result from an influx of blood monocytes into the peritoneum, and/or from local proliferation of peritoneal macrophages. Once in the peritoneal cavity, monocytes differentiate into tissue macrophages. Mononuclear phagocyte proliferation and differentiation are influenced by different cytokines, including macrophage colony-stimulating factor (M-CSF). The purpose of this study was to determine the relationship of M-CSF levels in human PF and plasma to the macrophage content, and to the patient diagnoses. Mean concentrations of PF M-CSF were higher than plasma levels (2.44 +/- 0.13 v 0.95 +/- 0.06 ng/mL, respectively). The mean concentrations of plasma M-CSF did not differ in samples from women of different diagnostic groups (normal, peritoneal adhesions, endometriosis, inactive pelvic inflammatory disease, uterine fibroids, and idiopathic infertility), but the PF concentration was slightly higher in normal women. The absolute (total) amount of PF M-CSF in normal women was lower than in those of the other diagnostic groups. The total amount of PF M-CSF in all women correlated closely with the total number of peritoneal macrophages. The tubal patency status (open versus closed) did not influence the plasma and PF concentrations of M-CSF, nor the PF absolute amount of M-CSF. The PF M-CSF may have come from peritoneal macrophages, fibroblasts, mesothelial cells, or endothelial cells. PF M-CSF may play important roles in the proliferation and/or the differentiation of peritoneal mononuclear phagocytes.

Ascitic Fluid↗
PubMed1991

Chronic morphine treatment selectively suppresses macrophage colony formation in bone marrow.

Opioids have been shown to have diverse effects on the immune system, both in vivo and in vitro, but their interactions on immature progenitor cells have been little studied. We have examined the effects of chronic morphine treatment of mice on colony formation by bone marrow cells in vitro. Bone marrow cells from mice implanted with morphine pellets for 72 h showed a 65% decrease in their response to macrophage colony stimulating factor (M-CSF). In contrast, chronic morphine treatment had no effect on the response of bone marrow cells to granulocyte/macrophage colony stimulating factor (GM-CSF). Removal of the morphine pellets from the mice resulted in a time-dependent reversal of the inhibition of macrophage colony formation, and the inhibition was completely blocked by simultaneous administration of naloxone and morphine pellets to the mice. No inhibition of colony formation was observed in bone marrow cells from mice treated with a single acute dose of morphine. Incubation of bone marrow cells from untreated mice for 7 days with in vitro morphine concentrations as low as 25 microM also reduced macrophage colony formation, and the opioid peptide beta-endorphin was even more potent, significantly reducing macrophage colony formation at concentrations as low as 0.25 microM. In agreement with the in vivo effects, neither opioid in vitro had a significant effect on granulocyte/macrophage colony formation. These results suggest that opioids may significantly alter the maturation of immune cells, which could result in potent effects on overall immune competence.

Animals↗
PubMed1991

Increased serum levels of macrophage colony-stimulating factor in ovarian cancer.

Macrophage colony-stimulating factor is a cytokine that stimulates proliferation and differentiation of phagocytic cells. Macrophage colony-stimulating factor is produced by ovarian epithelial cancer cell lines and might provide a useful serum marker for the disease. Among sera from 69 patients with clinically apparent epithelial ovarian cancer, 47 (68%) had at least 2.5 ng/ml macrophage colony-stimulating factor, whereas only two of 80 apparently healthy donors (2.5%) had a comparable elevation of macrophage colony-stimulating factor. Circulating levels of macrophage colony-stimulating factor did not correlate with serum levels of CA 125. Moreover, 14 of 25 ovarian cancer patients (56%) with clinically evident disease and normal levels of CA 125 (less than 35 U/ml) had elevated levels of macrophage colony-stimulating factor. Among 29 patients with serum CA 125 levels less than 35 U/ml before positive surgical surveillance procedures, 9 (31%) had at least 2.5 ng/ml macrophage colony-stimulating factor. Elevated levels of macrophage colony-stimulating factor were also found in patients with carcinomas from other primary sites and in 31% of 134 patients with benign diseases. If intercurrent benign disease can be taken into account, macrophage colony-stimulating factor deserves further evaluation in combination with CA 125 in monitoring ovarian cancer.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1991

Ribosomal inhibitory proteins from plants inhibit HIV-1 replication in acutely infected peripheral blood mononuclear cells.

Peripheral blood mononuclear cells from seronegative donors were stimulated with phytohemagglutinin and then infected with human immunodeficiency virus (HIV-1). Using this experimental system, the antiviral activity of two translation inhibitory proteins (pokeweed antiviral protein, PAP-S, and Luffa ribosomal inhibitory protein, LRIP-I) isolated from plants and a recombinant form of ricin A chain were studied. Previously, it had been shown that toxin polypeptides linked to monoclonal antibodies could inhibit HIV-infected cells. In the present study, the free, unconjugated, proteins were found to inhibit HIV replication at doses in which they were nontoxic to uninfected peripheral blood mononuclear cells. Among the inhibitory proteins, PAP-S and recombinant ricin A chain markedly reduced the reverse transcriptase activity and the expression of p24 core protein in infected cultures. Dose response studies indicate that the anti-HIV activity of PAP-S was comparable to AZT. The other ribosome inhibitory proteins (RIPs) showed moderate but significant antiviral activity.

Cell Survival↗
PubMed1991

Blood cholesterol and HDL cholesterol in cigarette smokers.

24 cigarette smokers were investigated for their blood cholesterol and HDL cholesterol. They had elevated total cholesterol compared to age and sex matched controls. 21 smokers out of 24 had significant decrease of HDL cholesterol. It is suggested that smoking, which is a major risk factor for coronary heart disease, might act through its effect on total cholesterol and HDL cholesterol.

Adolescent↗
PubMed1991

Double blind, placebo controlled trial on the cytoprotective effect of misoprostol in subjects with rheumatoid arthritis, osteoarthritis and seronegative spondarthropathy on NSAIDs.

Ninety arthritic patients were randomly allotted to receive misoprostol 200 micrograms thrice daily or placebo, for 4 weeks, while they were started on various NSAIDs. While upper gastrointestinal symptoms occurred equally in both groups, patients on placebo had significantly more post-therapy abnormal endoscopy findings. Misoprostol was well tolerated without any adverse side effects; it did not interfere with the therapeutic efficacy of the NSAIDs. Arthritic patients requiring long term NSAID therapy appear to benefit from misoprostol because of its cytoprotective effect on the gastrointestinal mucosa.

Adult↗
PubMed1991

Progressive systemic sclerosis in south India.

Seventy eight patients with progressive systemic sclerosis (PSS) were seen over a period of 14 years. They were analysed after clinical, haematological, biochemical, immunological and radiological investigations for comparison with other Indian and Western studies. Nine of the 78 were cases of childhood PSS. There was a female preponderance (3.9:1) and the peak age of occurrence was the 4th decade (32.1%). Arthralgia (53.8%) and skin thickening (70.5%) were the common presenting symptoms. Raynaud's phenomenon (28.2%) was less common. Involvement of the skin was present in all the patients and skin biopsy was positive in 96% of the cases. Joints were affected in 66.7%; internal organs were involved in 52.6%. Antinuclear antibody was positive in 56.8%. Abnormal echocardiography (37.6%) and barium studies (20.4%) were seen. Restrictive airway pattern by pulmonary function test was present in 55%. Death occurred in 5 patients, of whom 3 died of severe pulmonary hypertension.

Adolescent↗
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↗