Biomedical subjects

S Rajaraman

Publications and source records attributed to S Rajaraman.

At least 109 records · Page 6Linked to original sources

PubMed1990

Protective action of luminal bile salts in necrotizing acute pancreatitis in mice.

Bile salts in the intestinal lumen act to inhibit the release of cholecystokinin (CCK). Recent studies have shown that CCK may play a permissive role in the development of acute pancreatitis. In this study, the amount of luminal bile salts in female Swiss Webster mice was either decreased by feeding 4% (wt/wt) cholestyramine or increased by feeding 0.5% sodium taurocholate for 1 wk. Plasma levels of CCK were stimulated by cholestyramine and inhibited by taurocholate. Then, acute pancreatitis was induced either by caerulein injections, or by feeding a choline-deficient, ethionine-supplemented (CDE) diet. Feeding of cholestyramine significantly decreased survival from 25% to 0% in the CDE pancreatitis, and increased the magnitude of elevation of serum amylase levels and the extent of pancreatic necrosis in both models of pancreatitis; CCK-receptor blockade with CR-1409 completely abolished the adverse effects of cholestyramine. In contrast, feeding of taurocholate significantly increased survival to 100% and decreased the elevation of serum amylase and pancreatic necrosis; CCK-8 antagonized these actions of taurocholate. Luminal bile salts appear to provide a physiologic protection against necrotizing pancreatitis, at least in part, both by inhibiting the release of CCK and by promoting resistance of the pancreas to CCK excessive stimulation in vivo.

Acute Disease↗

PubMed1989

Contractile response of canine gallbladder and sphincter of Oddi to substance P and related peptides in vitro.

Substance P (SP) is a neurotransmitter peptide that is widely distributed in the body. Since SP has been demonstrated in the gallbladder (GB) and bile ducts of dogs, it may have a role in biliary motility. The objective of this study was to examine the effect of SP on the GB and sphincter of Oddi (SOD) of dogs in vitro, to evaluate the structure-activity relationship of SP, and to compare the contractile effect of SP with that of cholecystokinin octapeptide (CCK-8) and acetylcholine (Ach). Isolated longitudinal strips of GB and SOD from dogs were suspended in oxygenated Krebs buffer and the isometric tension responses to various doses of CCK-8, Ach, SP, and SP homologs [SP-free acid (SPFA), Octa-SP (O-SP), physalaemin (PHY)] were measured. We found that all the SP homologs, other than SPFA, stimulated GB and SOD contractions in vitro in a dose-dependent manner. The potency of SP and its homologs on GB and SOD was SP greater than or equal to PHY greater than O-SP; SPFA was without effect. CCK-8 was significantly more effective than SP on GB contraction, but unlike SP, CCK had no effect on SOD. The maximum contraction achieved by Ach was 1.3 (SOD) to 2.3 (GB) times greater than that achieved by SP, but the ED50 of SP was approximately 100- to 200-fold lower than that of Ach. The contractile effect of SP was partially blocked by 10(-5) M atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMed1989

Endogenous cholecystokinin regulates growth of human cholangiocarcinoma.

Exogenous administration of cholecystokinin (CCK) or caerulein inhibits growth of SLU-132, a human cholangiocarcinoma that we have shown to possess receptors for CCK. Chronic administration of cholestyramine, a resin that binds bile salts, increases release of CCK and growth of the pancreas in guinea pigs. Feeding the bile salt, taurocholate, inhibits meal-stimulated release of CCK. The purpose of this study was to determine whether endogenous CCK affects growth of the human cholangiocarcinoma, SLU-132. We implanted SLU-132 subcutaneously into athymic nude mice. The bile salt pool was depleted by feeding 4% cholestyramine for 40 days, either alone or enriched with 0.5% taurocholate for 32 days. When the mice were killed, tumors and pancreas were removed. Cholestyramine significantly inhibited the growth of SLU-132 and stimulated growth of the normal pancreas. Feeding of taurocholate acted to stimulate tumor growth. These results demonstrate that endogenous levels of CCK regulate growth of this human cholangiocarcinoma. Our findings suggest that manipulation of levels of endogenous gut hormones may, in the future, play a role in management of patients with certain gastrointestinal cancers.

Adenoma, Bile Duct↗

PubMed1989

A surgical treatment for vitiligo: autologous cultured-epithelial grafts.

Medical treatment of vitiligo has been disappointing; therefore surgical treatments using autologous grafts have been tried. We investigated a new technique in which normally pigmented epidermal cells from a vitiligo patient were cultured on a collagen-coated membrane in MCDB-153, a media that supports melanocytes and keratinocytes. The cell/collagen-coated membrane was used to cover a superficially dermabraded vitiliginous area. Clinical repigmentation, though incomplete, was evident in three of four patients in 4 weeks. Immunofluorescence and electron microscopy were performed on the grafted areas (involved and uninvolved controls). These studies demonstrate the reappearance of melanocytes and melanosomes within the grafted area. All three patients who were successfully repigmented retained their pigment at 1 year follow-up. Further investigation of this promising treatment for vitiligo is warranted.

Adult↗

PubMed1989

Cohesive properties of terminally differentiated keratinocytes.

The stratum corneum can be dissociated into single squames by several extraction methods: mechanically, with organic solvents, and with detergents. We have performed studied of reaggregation from single squames prepared by these methods. Mechanically dispersed corneocytes recombined into a lamellar-like structure closely resembling intact stratum corneum. Squames obtained by dissociation in ether formed a multilayered structure which differed from the intact tissue in the collapse of the bilayered lamellar structure into a single lucent band with osmiophilic deposits. Squames obtained after extraction with detergent failed to reaggregate.

Cell Adhesion↗

PubMed1989

Chemokinetic agents for monocytes in human milk: possible role of tumor necrosis factor-alpha.

Human milk was found to contain chemokinetic agents for human blood monocytes. The chemokinetic agents were whey proteins that were inactivated by heating at 56 degrees C for 20 min or treatment with trypsin. Three peaks of chemokinetic activity less than 60 kD in size were found by gel filtration chromatography. The chemokinetic activity of each peak obtained by gel filtration was partially blocked by polyclonal rabbit antibodies to recombinant human tumor necrosis factor-alpha (TNF-alpha). TNF-alpha, or a protein that immunologically cross-reacted with it, was also detected in human milk by blockage of the cytotoxicity of human milk by anti-TNF-alpha. Such proteins or others that elicit the release of TNF-alpha from the target cells may be responsible for the enhanced motility of human milk macrophages, and it is possible that they may alter the immunologic or metabolic activities of the alimentary tract of the recipient infant.

Female↗

PubMed1989

The effect of hyperbaric oxygen therapy of oral mucosal carcinoma.

Hyperbaric oxygen is sometimes used in the course of treatment in head and neck cancer patient. This study was undertaken to investigate the effect of hyperbaric oxygen on oral cavity carcinogenesis in an animal model. Dimethylbenzanthracene was applied three times weekly to induce oral squamous cell cancers. The group that received simultaneous hyperbaric oxygen had fewer tumors, but the tumors were larger than the dimethylbenzanthracene-only group. We concluded that hyperbaric oxygen has a tumor-suppressive effect during the induction phase of oral carcinoma and appears to have a stimulatory effect during the proliferative phase of carcinoma in this animal model.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1989

Involvement of cholecystokinin receptors in the adverse effect of glucocorticoids on diet-induced necrotizing pancreatitis.

The mechanism that explains the association between corticoids and acute pancreatitis is unknown. Our hypothesis was that chronic glucocorticoid treatment could adversely affect the course of hemorrhagic pancreatitis by acting through cholecystokinin (CCK) receptors. Acute necrotizing pancreatitis was induced by feeding young female mice a choline-deficient, ethionine-supplemented (CDE) diet for 60 hours. Treatment with hydrocortisone (10 mg/kg/day) was begun 1 week before pancreatitis. At the onset of the CDE diet, a group of hydrocortisone-treated mice were also given the CCK receptor antagonist CR-1409 (5 mg/kg three times a day). Control mice received injections of saline solution. A follow-up of 336 hours was conducted for survival analysis. Hydrocortisone given alone did not produce pancreatitis. Hydrocortisone, however, did increase the pancreatic necrosis caused by the CDE diet (from 40% to 70%) and significantly reduce survival (from 40% to 9%). CR-1409 completely abolished the adverse effects of hydrocortisone on pancreatitis. We measured amylase release by dispersed pancreatic acini from mice chronically treated with hydrocortisone in response to CCK-8. Treatment with hydrocortisone increased both the sensitivity and the responsiveness of the pancreas to CCK-8. We conclude that glucocorticoids alone may not induce acute pancreatitis, but they can increase the risk of a more severe form of pancreatitis developing. The glucocorticoid effect appears to be attributable to a CCK receptor-mediated sensitization of the pancreas to endogenous CCK. Thus, CCK-receptor blockade may improve survival in necrotizing pancreatitis associated with chronic glucocorticoid treatments.

Amylases↗

PubMed1988

Inhibition of human gastric adenocarcinoma xenograft growth in nude mice by alpha-difluoromethylornithine.

We studied the effect of inhibition of polyamine biosynthesis by alpha-difluoromethylornithine on the growth of a human gastric adenocarcinoma (CLEES) xenotransplanted in nude mice. CLEES is a well-differentiated gastric adenocarcinoma of the intestinal type. The doubling time has ranged from 7 to 10 days through 11 passages. Electron microscopic and immunohistochemical studies comparing the original tumor and xenotransplants showed similar structure and similar amounts of carcinoembryonic antigen. Polyamine biosynthesis is required for cell division. alpha-Difluoromethylornithine inhibits ornithine decarboxylase, the rate-limiting enzyme in polyamine biosynthesis. In this study, 48 athymic mice were used in two experiments. In the first experiment, two groups of 12 mice each were inoculated with CLEES tumor cells and received either tap water or a 3% alpha-difluoromethylornithine solution as drinking water. Tumor size was measured twice weekly. Tumor size was significantly decreased from controls by the fourth week of treatment and at all points of analysis thereafter for 7 wk. In the second experiment, alpha-difluoromethylornithine significantly reduced tumor concentrations of the polyamines putrescine and spermidine. In addition, the tumor content of DNA was significantly reduced in treated mice (0.64 +/- 0.16 mg) compared to controls (4.76 +/- 0.92 mg). Our data suggest that inhibition of polyamine biosynthesis may be a useful component of multidrug chemotherapy for human gastric adenocarcinoma. Establishment of tumor lines such as this gastric adenocarcinoma will facilitate further studies on the biological behavior of human gastric cancer and its response to chemotherapeutic manipulation in vivo.

Adenocarcinoma↗

PubMed1988

A novel neuronal antigen identified by sera from patients with systemic lupus erythematosus.

Using human neuroblastoma cell lines (IMR-6, NMB-7, SK-N-Mc, SK-N-SH) as sources, we characterized surface neuronal antigens as an initial step in determining the pathogenic role and clinical significance of neuronal antibodies in systemic lupus erythematosus (SLE) patients. SLE sera were screened for the presence of surface neuronal antibodies using a mixed hemadsorption assay. Thirty SLE sera were further tested by Western blotting and immunoprecipitation of lysed IMR-6 cells. Western blotting revealed binding to predominantly intracellular antigens, none of which was restricted to neuroblastoma cells. In contrast, immunoprecipitation experiments demonstrated binding to a 97K antigen, which appeared to be of surface origin, by 3 SLE sera. This was not present on non-neuronal cells and was not precipitated by sera from healthy or disease controls. This 97K antigen was also precipitated from the neuroblastoma cell line NMB-7, but was not present on SK-N-Mc or SK-N-SH cells. Precipitation was depleted by preabsorption with viable IMR-6 and NMB-7 cells, but not with non-neuronal cells. Thus, some SLE sera recognize a 97K neuronal antigen on select neuroblastoma cells.

Antibodies↗

PubMed1988

Glycoproteins modulate adhesion in terminally differentiated keratinocytes.

The stratum corneum can be dissociated into single squames by homogenization in ether. We have reaggregated the free corneocytes into a multilayered lamellar structure resembling an intact stratum corneum. The reconstituted stratum corneum reacts with fluorescein-conjugated lectins, unlike the intact tissue. We infer that the lack of binding in the intact tissue is due to masking of saccharide sites by lipids (which are extracted by the ether). In an extension of the procedure, the ether is removed and replaced by acetone. This system permits us to modulate corneocyte reaggregation by the addition of appropriate agents. We have used this system to corroborate our hypothesis that a 40 kD cell-surface glycoprotein (an endogenous lectin specific for amino sugars), which we have isolated from the stratum corneum, is instrumental in adhesion of corneocytes by cross-linking with amino sugar sites on adjacent cells. The reaggregation is inhibited by the antibody to the 40 kD glycoprotein. It is also inhibited by either the addition of amino sugars which bind to the endogenous lectin, or the addition of exogenous lectins specific for amino sugars which bind to the ligand.

Antibodies↗

PubMed1988

Purification of proteins from polyacrylamide gels, free of detergent or dye.

A two step procedure recovers proteins from sodium dodecyl sulfate polyacrylamide gels. The proteins are eluted by electrophoretic dialysis. The eluent is then passed through an Amberlite CG-400 anion-exchange resin. The recovery of protein is nearly total. The recovered proteins have no detectable sodium dodecyl sulfate contamination. With gels that have been stained with Coomassie Brilliant Blue R, the procedure recovers the proteins free of the dye. We have used this procedure successfully during the purification of epidermal glycoproteins.

Chromatography, Ion Exchange↗

PubMed1988

The motility of human milk macrophages in collagen gels.

The hypothesis that the diminished motility of human milk leukocytes is due to a decrease in adherence was tested by using a collagen gel system in which leukocyte movement is less dependent on adherence. Unfractionated human milk leukocytes (HML) or fractionated peripheral blood leukocytes were placed on collagen gels in microwells and the leading edge of migration was determined by inverted phase microscopy. The mean rates of invasion of HML, blood neutrophils, and mononuclear blood leukocytes were 14, 240, and less than 1 mu/h, respectively (p less than 0.01). We then examined the identity of motile HML by immunoperoxidase techniques using antibodies to selected cell markers. Motile HML were positive for a specific macrophage marker (cathepsin B) and a neutrophil and monocyte marker (Mac-1) but were negative for specific neutrophil (cathepsin G) or lymphocyte markers (CD3 and CD5). The directed motility of these cells was not enhanced by exposure to the chemoattractant, N-formyl-L-methionyl-L-phenylalanine, but was inhibited by a T cell lectin, phytohemagglutinin. The movement was actin dependent but was not dependent on calcium or Mac-1 surface glycoproteins. Thus, the diminished motility of milk neutrophils does not appear to be due to decreased adherence per se, and those HML that are motile are macrophages. This suggests a dichotomy for the function of HML. Neutrophils may be relegated to the lumen of th alimentary tract, whereas macrophages may penetrate into mucosal sites for host defense.

Cell Migration Inhibition↗

PubMed1988

Establishment of a human gastrinoma in nude mice.

We report the first establishment and characterization of functioning gastrinoma from a human being transplanted into nude mice. Tissue was obtained at operation from a gastrinoma liver metastasis from a patient with the Zollinger-Ellison syndrome. The tumor was implanted subcutaneously in five athymic nude mice. Serum gastrin was measured by means of radioimmunoassay in specimens of mouse blood taken before and 5 minutes after intraperitoneal injection of secretin (100 micrograms/kg). In a second experiment serum gastrin was measured 30 minutes after injection of somatostatin analogue, SMS 201-995 (300 micrograms/kg). Studies were also done in 10 control mice. At passage, the fundus of each tumor-bearing mouse was weighed and examined microscopically. The gastrinoma (tumor line, PT) has been maintained for 34 months through four passages with a tumor doubling time of 37 to 45 days. The histology is similar to the original tumor. Immunocytochemistry showed that PT contained gastrin. In two mice metastasis developed 9 months after implantation. Gastrin levels in mice bearing PT have ranged from 216 to 12,000 pg/ml. Gastrin levels of control mice ranged from 0 to 63 pg/ml. Secretin increased gastrin levels in three of five mice tested and decreased gastrin levels in two mice. Repeat secretin tests showed identical results. SMS 201-995 decreased gastrin levels from basal values. Fundic weight of mice bearing PT (397 +/- 93 mg) was significantly greater than control fundic weight (180 +/- 26 mg). Gastrinomas growing in nude mice produce physiologically active gastrin as shown by elevated serum gastrin levels and by hyperplasia of the stomach. Two distinct subpopulations of gastrinoma cells respond differently to secretin. This model should provide important information on mechanisms of growth control and on gastrin release by gastrinomas in human beings.

Adult↗

PubMed1987

Primary transfection as a mechanism for transformation of host cells by human tumor cells implanted in nude mice.

Establishment of cell lines in vitro from a human lung cancer xenograft in nude mice resulted in transformed mouse cell lines. The transformed mouse cell lines expressed both mouse-specific and human-specific histocompatibility antigens. Of 3 cell lines, 2 were tumorigenic in BALB/c nude mice but not in normal mice. Tumors formed by the transformed mouse cell lines were fibroblastoid and epithelioid by histology. In addition, tumors exhibited neuroepithelial differentiation by ultrastructural and immunohistochemical analysis. Phenotypically they were similar to the original patient and human xenograft tumor. These data suggest that previous reports of host cell transformation and induction of fibrosarcomas may not be true fibrosarcomas. Human DNA sequences were present in the tumorigenic cell lines, indicating that spontaneous transfection of human tumor DNA into host cells had occurred. The implication of these findings is that human genetic information has been transferred to primary mouse host fibroblasts, which resulted in a transformed as well as a differentiated phenotype.

Animals↗

PubMed1987

Fetal intestinal transplants in syngeneic rats: a developmental model of intestinal immunity.

We conducted a longitudinal study of the development of lymphoid tissue in fetal small intestine transplanted to a subcutaneous site in adult syngeneic Fischer strain rats. Fetal jejunoileal segments obtained between 18 and 21 days of gestation were transplanted to a dorsal subcutaneous site on syngeneic adult rats. Three weeks later, intestinal segments greater than 2.5 cm in length were found in 70% of recipients. Each week for 6 wk post-transplantation, a full-thickness biopsy was obtained for histologic and immunohistologic examination. At the time of transplantation, fetal rat intestine did not display Peyer's patches, intraepithelial lymphocytes, lymphoid follicles, or IgA-containing plasma cells. These lymphoid structures reached adult levels by 4 wk after transplantation, and the sequence of development of the lymphoid structures in the transplants appeared to match the postnatal development of normal small intestine. After immunizing the in situ intestine or the transplanted fetal intestine with cholera toxin, the number of cells producing specific antibodies to the immunogen increased significantly in intestinal transplants and in situ intestine. In contrast, few if any cells synthesizing antibodies to cholera toxin developed in the transplants after i.p. immunization. This study suggests that fetal intestinal transplants behave as part of the mucosal immune system. This model may provide useful approaches to studying the development of mucosal immunity.

Animals↗

PubMed1987

Ultrastructural and immunohistochemical evidence for release of eosinophilic granules in vivo: cytotoxic potential in chronic eosinophilic pneumonia.

We studied a patient with relapsing idiopathic chronic eosinophilic pneumonia. Each one of four attacks observed during a 4-year period was characterized by dyspnea, wheezing, peripheral blood eosinophilia, elevated serum IgE levels, and pulmonary infiltrates. Glucocorticoid therapy caused prompt resolution of symptoms and disappearance of blood eosinophilia and pulmonary shadowing. Electron microscopy and tissue immunofluorescence studies for major basic protein documented extensive eosinophil degranulation and the presence of free granules within the pulmonary microvasculature. In addition, exfoliation of the alveolar lining cell was observed in association with a clustering of free intact and disintegrating extracellular eosinophil granules against a denuded basement membrane. These findings suggest a cytotoxic potential of the eosinophil at the level of the pulmonary parenchyma in a case of idiopathic chronic eosinophilic pneumonia.

Cytoplasmic Granules↗

PubMed1987

Somatostatin secretion in cultured human islet cells from patients with nesidioblastosis: a compensatory mechanism?

Two patients with nesidioblastosis, one with persistent hypoglycemia and another who was asymptomatic, underwent pancreatic resection. Dispersed pancreatic islets were prepared from each patient. Insulin secretion from cultured islet cells was increased and somatostatin decreased in the symptomatic patient compared with the asymptomatic patient. Immunocytochemistry showed increased somatostatin-containing cells in the asymptomatic patient. We hypothesize that this may be the mechanism by which some patients with nesidioblastosis maintain normal serum glucose levels.

Cell Separation↗