Increased lens dipeptidase activity in aging and cataract.
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Adult↗
Biomedical subjects
S Ramakrishnan
Publications and source records attributed to S Ramakrishnan.
Transforming growth factor-alpha levels in the serum and ascites of patients with advanced epithelial ovarian cancer.
A variety of cytokines have been identified to play a role in ovarian cancer. In this pilot study, we sought to determine whether transforming growth factor-alpha (TGF-alpha) was detectable in the serum and ascites of women with advanced stage epithelial ovarian cancer. TGF-alpha was measured using an enzyme-linked immunosorbent assay and was present in 18 of 25 control sera. Prior to treatment for stage III or IV epithelial ovarian cancer, 18 patients had undetectable serum levels of TGF-alpha, while 18 had values ranging from 10.6 to 531.7 pg/ml. The group with undetectable levels had a 6-month greater median survival; detectable TGF-alpha might be a negative prognostic indicator. In a separate group undergoing second-look laparotomy, differences in median TGF-alpha values versus controls and the primary study group approached significance. TGF-alpha was detected in significantly more control peritoneal fluid samples than in patient ascites. A larger study is warranted.
Ascites↗
Two new functions of inositol in the eye lens: antioxidation and antiglycation and possible mechanisms.
The extent of glycation of human eye lens proteins with glucose in presence of added inositol was examined in vitro using [U14C] glucose. Lens homogenate was reacted with varying concentrations of glucose and glucose + inositol. At the end of the reaction, the proteins were precipitated with TCA, centrifuged, dissolved in NaOH and the radioactivity was measured. Inositol decreased the glycation by 57-67%. Pure inositol and glucose suitably labelled with 3H or 14C when reacted and followed by paper chromatography and HPLC showed that glucosyl inositol was present along with unreacted free glucose. Preliminary studies made of the UV spectra of pure inositol (i) when reacted with H2O2 showed that inositol removed H2O2 from the reaction mixture (ii) when reacted with arachidonic acid showed that they formed a conjugate. The observations indicate that the antioxidant property of inositol could be the result of its' quenching action on reactive oxygen, intermediates and conjugate-formation with compounds like arachidonic acid and the antiglycating property due to scavenging of glucose. The antioxidant and the antiglycating properties of inositol may be beneficial in delaying or averting cataract.
Antioxidants↗
Effect of local anesthetics on red blood cell deformability.
The deformability of human red blood cells under the influence of local anesthetics is studied in vitro. Red blood cells obtained from blood samples of healthy adult volunteers are treated with two local anaesthetics, procain and tetracaine, at varied concentrations. Deformability of red blood cells, in terms of its elongation index, were then examined by laser light shear stress diffractometer both at low and high shear forces. Results show that the deformability of local anesthetic-treated red blood cells is decreased when compared to that of control samples. At low shear forces and at low concentrations of the anesthetic agent, the decrease in deformability is not significant, whereas it is significant for high shear forces and at high concentrations. These effects are similar for both anesthetic agents studied.
Adult↗
Evaluation of hemorheological risk factor profile in plasmacytoma patients.
The hemorheological parameters, plasma viscosity, hematocrit, erythrocyte aggregation and deformability of blood samples obtained from plasmacytoma patients are measured by capillary viscometer, microcentrifuge, Myrenne aggregometer, and filtrometer, respectively. These parameters are significantly altered in patients compared to those of normal subjects. The plasma viscosity and erythrocyte aggregation are increased, whereas erythrocyte deformability and hematocrit are decreased. Based on these parameters the hemorheological risk factor profiles are developed and by their overall risk factors, the patients with low and high risk factors are identified.
Blood Viscosity↗
Influence of local anaesthetics on the aggregation and deformability of erythrocytes.
The effects of two local anaesthetics, procain and tetracaine, on erythrocyte aggregation and deformability under in vitro conditions are analysed. Fresh blood samples from healthy volunteers are obtained by venepuncture in test tubes containing heparin as anticoagulant. After centrifugation, plasma and cells are separated and buffy coat is discarded. The erythrocyte suspensions for aggregation and deformability measurement are prepared at hematocrit 34 and at 8% in buffered medium containing glucose and albumin, respectively. A part of the suspending medium in these samples is replaced by an equal volume of anaesthetic solution to obtain its final concentration ranging from 0.001 to 1 g/l. The results show that with the increase of anaesthetic concentration the deformability index and the aggregation index are reduced. The change in erythrocyte shape may contribute to the decrease in aggregation. The combined effect of these parameters may affect blood flow under varied experimental conditions.
Anesthetics, Local↗
Transthyretin (prealbumin) in eye structures and variation of vitreous-transthyretin in diseases.
PURPOSE: To evaluate the presence of transthyretin (TTR, prealbumin) a protein which binds retinol to retinol-binding protein in various ocular tissues and to study its quantitative changes in the vitreous humor in various diseases. METHOD: Estimation of TTR was done by electrophoresis of 10 mg protein in each sample of tears, aqueous humor, vitreous, retina, and lens by an Imaging Densitometer using prealbumin as the standard. RESULTS: TTR was present in all the eye structures except the lens and tear. The retina and the vitreous had relatively higher amounts of TTR compared with aqueous. The identity of TTR was confirmed by immuno-electrophoresis using anti-human TTR. Two bands in SDS electrophoresis revealed that this protein is a heterodimer. There was a significant decrease in vitreous TTR in diabetes with hypertension and increase in one case each of diabetes with hypertension associated with leukaemia or carcinoma with hepato-splenomegaly. CONCLUSION: Vitreous TTR is probably from retina and retinal pigment epithelium. The level of vitreous TTR is likely to have diagnostic significance in some retinal diseases.
Adult↗
Antitumor response elicited by a superantigen-transmembrane sequence fusion protein anchored onto tumor cells.
Superantigens stimulate T cells bearing certain TCR beta-chain variable regions when bound to MHC II molecules. We investigated whether the superantigen toxic shock syndrome toxin-1 (TSST1) could induce an antitumor immune response when anchored onto MHC II-negative tumor cells. Our approach was to facilitate association of TSST1 with cell membranes by fusing its coding region to the transmembrane region (TM) sequence of the proto-oncogene c-erb-B-2. TSST1-TM was expressed in bacteria with an N-terminal histidine tag and purified using nickel-agarose affinity chromatography. Purified TSST1-TM added to cultures of several different MHC II-negative tumor cells spontaneously associated with cell membranes, as detected by flow cytometry. Because superantigens can direct cell-mediated cytotoxicity against MHC II-positive cells, a TM fusion protein lacking the TSST1 MHC II binding domain (TSST(88-194)-TM) was also constructed. Tumor cells precoated with TSST1-TM or TSST(88-194)-TM stimulated proliferation of human peripheral blood lymphocytes in vitro whereas uncoated tumor cells did not. Mice preimmunized with TSST1-TM- or TSST(88-194)-TM-coated tumor cells mounted a systemic response that resulted in significant antitumor immunity as measured by regression of a parental tumor challenge. TSST1-TM and TSST(88-194)-TM fusion proteins represent a useful new strategy for attaching superantigens or potentially other proteins onto tumor cell surfaces without genetic manipulation.
Animals↗
Expression profile of the putative catalytic subunit of the telomerase gene.
Telomerase, a ribonucleoprotein complex, adds hexameric repeats called telomeres to the growing ends of chromosomal DNA. The enzyme telomerase activity is present in a vast majority of tumors but is repressed in most normal tissues. Recently, two groups have reported the molecular cloning of the putative catalytic subunit (hEST2/hTRT) of the telomerase gene. We investigated the expression of this gene in diverse tumor-derived cell lines and tumors as well as in various normal tissues. The expression of hEST2/hTRT was detectable in tumor-derived cell lines, primary breast tumors, pancreatic tumors, and kidney tumors. Furthermore, the expression of hEST2/hTRT was down-regulated in response to a differentiation inducer. However, several normal tissues also expressed varying levels of hEST2/hTRT. Early passage cultures of endothelial fibroblasts and some epithelial cells also expressed the telomerase gene, albeit at low levels. In contrast, the expression of TLP1/TP1, the human homologue of Tetrahymena p80 telomerase subunit, was similar in all of these samples. Our results indicate that the differences in expression of hEST2/hTRT in tumor versus normal cells are relative and are not absolute.
Breast Neoplasms↗
Separation of function between the domains of toxic shock syndrome toxin-1.
Toxic shock syndrome toxin-1 (TSST1) is a superantigenic exotoxin produced by certain strains of Staphylococcus aureus Structurally, TSST1 is composed of two domains: residues determined by crystallography to directly interact with MHC II molecules reside within the N-terminal domain, while TSST1 residues critical for superantigenicity are within the C-terminal domain. In this study, we expressed the individual N- and C-terminal domains of TSST1 in Escherichia coli and studied their biologic activities. The TSST1 N-terminal domain (TSST(1-87)) did not induce proliferation of human PBLs or release of TNF-beta, but did induce TNF-alpha release. However, TSST1-elicited proliferation and release of both TNF isoforms were inhibited by a molar excess of TSST(1-87). The TSST1 C-terminal domain (TSST(88-194)) did not bind MHC II molecules, yet it elicited production of TNF-alpha and TNF-beta, and induced TCR Vbeta-specific proliferation similarly to intact TSST1. When covalently cross-linked to tumor cells, TSST(88-194) elicited a local in vivo antitumor response indistinguishable from TSST1. Although intact TSST1 causes lethal shock in vivo, the individual domains of this molecule may have therapeutic potential: the N-terminal domain to antagonize lymphocyte activation and TNF release during acute TSST1-precipitated toxic shock syndrome, and the C-terminal domain to stimulate antitumor responses without MHC II binding.
Animals↗
Beneficial effect of lysine and amino acids on cataractogenesis in experimental diabetes through possible antiglycation of lens proteins.
Rats were given a single injection of streptozotocin. They became diabetic with a blood sugar of around 300 mg dL-1. They were divided into three groups of six rats each. Group II was the diabetic control. Each one of group III diabetic rats received daily 2 ml of 2% solution of lysine supplement orally. Group IV received daily 2 ml of a 2% solution of a mixture of amino acids supplement for 120 days. In addition there were 6 rats as normal control (Group I). Periodically ophthalmic examination was done by slit lamp. Blood glucose, proteins, hemoglobin, free amino acids, glycosylated hemoglobin and glycated lens proteins were also analysed. Body weight was recorded. The diabetic controls decreased in body weight. The blood sugar levels were lowered from about 295 mg dL-1 to 99 mg dL-1 in the lysine-fed group and from 268 mg dL-1 to 126 mg dL-1 in the amino acids mixture-fed group. The levels of glycosylated hemoglobin and glycated lens proteins increased in diabetic controls while they were normal in other groups. The free amino acid levels in blood were lower in groups receiving lysine or amino acids than in diabetic controls indicating their better utilization. In diabetic control, all the animals developed cataract in 70-90 days; five out of six did not develop cataract in the lysine supplemented group. Four of six did not develop cataract in the amino acid mixture-supplemented group. None developed cataract in normal controls. Lysine and amino acids have anticataractous and antidiabetic effects.
Amino Acids↗
Haemorheological behaviour of erythrocytes & risk factor profile in patients suffering from Waldenström's macroglobulinaemia.
The plasma viscosity, haematocrit, and erythrocyte aggregation and deformability of blood samples of patients of Waldenström's macroglobulinaemia were measured by capillary viscometer, microcentrifuge, Myrenne aggregometer and filtrometer respectively and correlated with the serum IgM concentrations. The observed increase in plasma viscosity and erythrocyte aggregation and decrease in their deformability were attributed to the increase in the concentration of IgM. Haematocrit was also decreased compared to normal subjects. Based on these parameters a haemorheological risk factor profile was developed and an overall risk factor calculated. An increase in the risk factor in these patients was observed. The haemorheological profile and the calculated risk factors not only help in establishing the inter-relationship of these parameters in the disease state but also to evaluate the severity of the disease.
Aged↗
The integration of a novice user interface into a professional modeling tool.
This paper describes a software tool, the Oncology Thinking Cap (OncoTCAP) and reports on our efforts to develop a novice user interface to simplify the task of describing biological models of cancer and its treatment. Oncology Thinking Cap includes a modeling tool for making relationships explicit and provide dynamic feedback about the interaction between cancer cell kinetics, treatments, and patient outcomes. OncoTCAP supports student learning by making normally invisible processes visible and providing a representational tool that can be used to conduct thought experiments. We also describe our novice interface and report the results of initial usability testing.
Cell Cycle↗
Vascular endothelial growth factor (VEGF) expression and survival in human epithelial ovarian carcinomas.
Vascular endothelial growth factor (VEGF) expression and microvessel density were studied in cases of advanced epithelial ovarian carcinoma to evaluate their usefulness as prognostic variables. Tumor samples from 18 patients with advanced stage serous epithelial ovarian cancer were evaluated for VEGF expression by reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. Immunohistochemical study of corresponding archival tissues with an antibody to von Willebrand factor (vWF; FVIII-RA) was used for tumor microvessel count determinations. The correlation of VEGF expression and mean microvessel counts was determined by an unpaired t-test. Survival analysis for known prognostic factors and VEGF expression was performed. Survival distributions were calculated by the product limit of Kaplan and Meier and significant differences between distributions were analyzed with a log rank test. From the RT-PCR analysis of tumor VEGF expression, 12 samples were found to be strongly positive, whereas six samples had low/negative VEGF expression. The median survival was 60 months for the VEGF-low/negative group and 28 months for the VEGF-positive group (P = 0.058). Other prognostic variables had minimal impact on survival, i.e. age < 65 years (P = 0.873), FIGO stage (P = 0.06), grade (P = 0.236) and debulking status (P = 0.842). Fourteen of 18 tumor specimens were suitable for microvessel counting. The mean microvessel counts of the VEGF-positive group and the VEGF-negative group were 27/hpf and 35/hpf, respectively (P = 0.16). In this preliminary analysis, high VEGF expression in epithelial ovarian carcinomas was associated with poor overall survival. Further study will be necessary to elucidate the lack of association of VEGF expression and tumor microvessel counts.
Adult↗
Targeting the tumor vasculature: inhibition of tumor growth by a vascular endothelial growth factor-toxin conjugate.
Tumor-derived vascular endothelial growth factor (VEGF)/ vascular permeability factor (VPF) plays an important role in neovascularization and the development of tumor stroma. Furthermore, VEGF receptors are over-expressed in the endothelial cells of tumor vasculature and almost non-detectable in the vascular endothelium of adjoining normal tissues. The differential expression of receptor offers a selective advantage for targeting cytotoxic toxin polypeptides. We have prepared a vascular targeting reagent by chemically linking recombinant VEGF to a truncated form of diphtheria toxin. The VEGF-toxin conjugate was selectively toxic to endothelial cell lines and inhibited experimental neovascularization of the chick chorioallantoic membrane. In the present study, we examined the effects of VEGF-toxin conjugate on solid tumor growth. Athymic nude mice with established subcutaneous tumors were treated with daily intraperitoneal injections of the VEGF-toxin conjugate or free toxin. When compared with control animals treated with the toxin polypeptide alone, the conjugate-treated animals displayed a significant inhibition of tumor growth. Histological analysis of tumors from conjugate-treated animals revealed hemorrhagic necrosis consistent with a vascular-mediated injury. In contrast, highly vascularized normal tissues from conjugate-treated animals demonstrated no evidence of hemorrhage or tissue injury. The conjugate was well tolerated without apparent toxicities. Our results illustrate the anti-tumor activity of a VEGF-toxin conjugate selectively targeting the tumor neovasculature.
Animals↗
Alpha-1 acid glycoprotein is an immunosuppressive factor found in ascites from ovaria carcinoma.
BACKGROUND: Although the ascites of patients with ovarian carcinoma has been reported to contain immunosuppressive factors, the identity and source of this activity has not been fully elucidated. The objective of this study was to describe the purification of a single immunosuppressive protein, alpha-1 acid glycoprotein, from ovarian carcinoma ascites, identify its site of production, and describe a possible mechanism by which it inhibits lymphocytes. METHODS: Ascites from proteins from five patients with epithelial ovarian carcinoma first were differentially precipitated by size with different concentrations of polyethylene glycol and then separated on the basis of isoelectric focusing. The protein factions then were placed in a lymphocyte proliferation assay to determine immunosuppressive activity. Western blot analysis was used to identify alpha-1 acid glycoprotein as an immunosuppressive protein in ascites. Total RNA was extracted from ovarian and hepatic cell lines as well as primary and recurrent ovarian tumor samples. Reverse-transcriptase polymerase chain reaction then was utilized to identify the site of production of this protein. Purified alpha-1 acid glycoprotein was placed in lymphocyte culture and its effects on lymphocyte interleukin-2 (IL-2) production were measured by enzyme-linked immunoadsorbent assay. RESULTS: Addition of purified alpha-1 acid glycoprotein to the lymphocyte assay resulted in a 60% decrease in lymphocyte proliferation (P < 0.05). Alpha-1 acid glycoprotein transcript was not identified in ovarian tumor cells. The addition of purified alpha-1 acid glycoprotein to the lymphocyte culture resulted in a 65% decrease in IL-2 secretion into the media (P < 0.05). CONCLUSIONS: Alpha-1 acid glycoprotein is an immunosuppressive protein purified from ovarian carcinoma ascites. It is not expressed primarily by ovarian carcinoma cells. It appears to inhibit IL-2 secretion by lymphocytes.
Ascites↗
Characterization of human telomerase complex.
Telomerase, a ribonucleoprotein complex, adds hexameric repeats called "telomeres" to the growing ends of chromosomal DNA. Characterization of mammalian telomerase has been elusive because of its low level of expression. We describe a bioinformatics approach to enrich and characterize the human telomerase complex. Using local sequence homology search methods, we detected similarity of the Tetrahymena p80 subunit of telomerase with the autoantigen Ro60. Antibodies to Ro60 immunoprecipitated the telomerase activity. Ro60 and p80 proteins were cross-recognizable by antibodies to either protein. Telomerase activity and the RNA component of telomerase complex were localized to a doublet in a native gel from the Ro60 antibody-precipitated material. The enriched material showed specific binding to a TTA GGG probe in vitro in an RNA template-dependent manner. Polyclonal antibodies to the doublet also immunoprecipitated the telomerase activity. These results suggest an evolutionary conservation of the telomerase proteins.
Amino Acid Sequence↗
Morphine inhibits transcriptional activation of IL-2 in mouse thymocytes.
Chronic treatment of mice with morphine affects the proliferation, differentiation, and function of immune cells. In the present study, we investigated the mechanism by which morphine inhibits phytohemagglutinin (PHA)/interleukin-1 (IL-1)-induced thymocyte proliferation. When compared to control cultures, morphine-treated thymocytes showed decreased steady-state levels of bioactive IL-2 and IL-2 mRNA. The reduced IL-2 concentration and reduced transcript levels correlated well with a decreased rate of synthesis of IL-2 mRNA as determined by nuclear runoff assays. Subsequent studies showed that morphine treatment affected transcriptional control elements of the IL-2 promoter by inhibiting the synthesis of a specific trans-activating nuclear factor, c-Fos. c-Fos mRNA levels measured by semiquantitative RT-PCR were significantly decreased in thymocytes following treatment with morphine and activation with PHA and IL-1. Under identical conditions, c-Jun mRNA levels were not altered. Electrophoretic mobility shift studies with the AP-1 consensus oligonucleotide showed significantly decreased levels of AP-1-protein complex formation in nuclear extracts prepared from morphine-treated cells. These studies demonstrate for the first time that opioid alkaloids such as morphine can impair mitogen-lymphokine-activated thymocyte proliferation by interfering with transcriptional activation of the IL-2 gene.
Animals↗