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Biomedical subjects

M Pinto

Publications and source records attributed to M Pinto.

At least 91 records · Page 5Linked to original sources
PubMed1985

Enterocytic differentiation and glucose utilization in the human colon tumor cell line Caco-2: modulation by forskolin.

The human colon cancer line Caco-2 exhibits after confluency a concomitant increase of glycogen accumulation and an enterocytic differentiation. The purpose of this work was to investigate whether forskolin (FK), an activator of adenylate cyclase, would induce a permanent glycogenolysis and, if so, whether it would result in modifications of the differentiation pattern of the cells. FK activates adenylate cyclase in Caco-2 cells with an ED50 of 7 X 10(-6)M. Three different treatment protocols with FK (10(-5)M) were applied: 1) the cells were treated during all the time in culture (20 days); 2) the treatment was started after confluency; 3) the treatment was interrupted after confluency. The presence of FK results in a permanent stimulation of cAMP accumulation (10 to 20 fold the basal values) and in a permanently reduced glycogen content (30 or 50% of the control values). The rates of glucose consumption are increased three and five fold in protocols 1 and 3 respectively. These metabolic changes are associated with morphological changes (tightening of the intercellular spaces and shortening of the brush border microvilli) and with a dual inhibition of the activities of brush border hydrolases: a) an inhibition of the post-confluent increase of activity of sucrase, aminopeptidase N and alkaline phosphatase in the brush border enriched fraction; b) an inhibition of the post-confluent increase of activity of sucrase in the cell homogenate. A comparison of the results obtained in each protocol shows that the morphological modifications and the decrease of the enzyme activities in the brush border fraction are regularly associated with an increased cAMP accumulation, whereas the inhibition of the differentiation of sucrase is a direct consequence of the increase in glucose consumption and decrease in glycogen stores.

Cell Line↗
PubMed1985

Short rib-polydactyly syndrome: a single or heterogeneous entity? A re-evaluation prompted by four new cases.

Four cases of lethal short rib-polydactyly syndrome (SRPS) from three non-consanguineous families are described. Radiological features were similar in all four cases and were most consistent with type III SRPS (Verma-Naumoff syndrome), but many differences in external and systemic abnormalities were noted. The considerable overlap of supposedly distinctive features displayed by the three main forms of SRPS is suggestive of a single locus mutation with variable expressivity, particularly for types I and III, possibly related to different mutant alleles and secondary intrauterine modification of the phenotype. All four cases showed anomalous sexual development. In spite of testicular differentiation in all four and a 46, XY karyotype in the two on whom chromosome studies were done, two infants were phenotypic females and two had ambiguous genitalia. A definitive diagnosis of SRPS was made at 26 weeks' gestation in a pregnancy at risk.

Chromosome Mapping↗
PubMed1985

Epithelial properties of human colonic carcinoma cell line Caco-2: effect of secretagogues.

Human colonic carcinoma Caco-2 cells grown in vitro form epithelial layers of highly polarized cells. Unlike colonic adsorptive cells they possess a mucosal membrane with very limited ionic conductance, even after exposure to aldosterone. When grown on filters, Caco-2 cells were sensitive to various secretagogues; these included 10(-5) M dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) and 10(-10) M vasoactive intestinal peptide, both of which, added serosally, enhanced the short-circuit current. The same applied to mucosal forskolin. Caco-2 cell sensitivity to serosal epinephrine was lower. Ion substitutions and 22Na-36Cl flux measurements indicated the possibility of secretagogue-dependent chloride secretion. Measurements on cells grown on Petri dishes and exposed to 1 mM DBcAMP for 1 h enabled detection of more profound modifications. Sustained 20-mV cell depolarization and a large reduction in the relative electrical resistance of the mucosal membrane were concomitant with a sizable decrease in 36Cl accumulation. These results suggest that Caco-2 cells, which to some extent resemble colonic crypt cells, possess the cAMP-dependent mucosal chloride conductance characteristic of secretory cells.

Bucladesine↗
PubMed1984

Aldosterone binding in the human colon carcinoma cell line HT29: correlation with cell differentiation.

The purpose of the present study is to investigate aldosterone binding to human colon carcinoma HT29 cells. These cells grow as undifferentiated epithelial cells when cultured under standard conditions (Dulbecco's MEM; 10% FCS). Modification of the culture medium induced two types of differentiation: (1) enterocytic differentiation when glucose (25 mM) is replaced by galactose (5 mM) (2) mucus secreting cells in FCS free medium. Aldosterone specific binding was detected in the cytosolic fraction of enterocyte-differentiated cells. This binding corresponded to a single class of sites with affinity, specificity and anion-exchange chromatographic behaviour similar to those observed in the epithelial crypts of human colon. These putative aldosterone receptors were also detected in mucus secreting cells that are derived from the enterocyte-differentiated cells. Enterocytic differentiation appears thus to be a necessary step for the "induction" of aldosterone receptors in HT29 cells.

Aldosterone↗
PubMed1984

Epithelial properties of human colonic carcinoma cell line Caco-2: electrical parameters.

Human colonic carcinoma Caco-2 cells grown in vitro undergo epithelial differentiation. Electrical measurements showed that they form resistant monolayers of polarized cells. On millipore filters, transepithelial electrical resistance (154 +/- 6.5 omega X cm2) was accompanied by a small potential difference (0.29 +/- 0.02 mV, serosal side positive) and by short-circuit current (1.9 +/- 0.14 microA X cm-2), both of which were ouabain sensitive. Micropuncture of domes formed on plastic supports under standard culture conditions revealed electrical polarity similar to that of filter-grown cells (0.8 +/- 0.2 mV, serosal side positive) combined with a highly negative cytoplasm (-57 +/- 1 mV) and very marked cell asymmetry (76% of total electrical cell resistance was located in the mucosal membrane). These parameters were not affected by the diuretic amiloride nor the hormone aldosterone, suggesting that sodium conductance is very limited in the mucosal membrane. Addition to the mucosal side of the ionophore nystatin or amphotericin B unmasked the possibility of high electrical transport activity. Electrical measurements made it possible to define the epithelial properties of Caco-2 cells, which may resemble those of colonic crypt or fetal cells. These measurements also confirmed that functional differentiation is homogeneous in Caco-2 cells. It is suggested that dome cell micropuncture may be useful in investigating the functional properties of other dome-forming cell lines.

Adenocarcinoma↗
PubMed1984

Metergoline in the management of normoprolactinemic secondary amenorrhea. A multicentric controlled trial.

In a multicentric study, the effect of the antiserotoninergic agent metergoline was evaluated in the management of patients with idiopathic normoprolactinemic secondary amenorrhea (NSA). The awareness that psychological factors might lead to a spontaneous reappearance of menses was also taken into account, and all the patients, after physical, gynecological and laboratory examinations, and the performance of the progesterone withdrawal bleeding test (100 mg i.m.) and the clomiphene citrate test (100 mg p.o./day for 5 days), were treated for 60 days with placebo; only patients showing no menses during placebo administration were later treated with metergoline. 108 patients entered the trial: of these, 48 experienced menses on admission or during placebo administration, and were withdrawn. Of the 60 patients not responding to placebo, 50 were treated for 90 days with metergoline (4 mg t.i.d.), and 23 had menses, ovulatory in 68.4% of cases. A new placebo treatment was accompanied, in the majority of cases, by recurrence of amenorrhea. These results indicate that many patients with NSA may experience a spontaneous disappearance of the disease: in cases more seriously affected metergoline might be a useful therapeutic agent.

Amenorrhea↗
PubMed1983

Sucrase-isomaltase: a marker of foetal and malignant epithelial cells of the human colon.

The presence of sucrase-isomaltase (SI), a glycoprotein hydrolase normally restricted to the brush border membrane of the enterocytes of the small intestine, was investigated in tumours which developed in nude mice inoculated with six human colon carcinoma cell lines (HT-29, Caco-2, HRT-18, HCT-8R, SW-480, and CO-115). Foetal and normal adult human small intestines and colons were used as controls. SI was studied by (1) immunofluorescence with rabbit antibodies raised against purified human small intestine SI; (2) polyacrylamide gel electrophoresis and immunoblotting; and (3) determination of the enzyme activity. SI was antigenically present, and enzymatically active, in all the tumours derived from Caco-2 and HT-29 cells. The presence of the enzyme was associated with that of typical brush borders at transmission electron microscopy examination. SI was absent from the tumours developed with the other four cell lines, as well as from the normal adult colon mucosa. SI was also present and active in the colons of mid-gestation foetuses, ranging in ages between 20 and 28 weeks; it was absent from the colons of late-gestation foetuses. The presence of SI in tumours derived from two cell lines suggests that this enzyme is a marker, so far unsuspected, of certain human colon cancers, and that the differentiation pattern of these particular cancers closely resembles that of the foetal colon.

Animals↗
PubMed1983

Persistent plaque formation in experimental murine brucellosis.

Primary plaque forming cells (PFC) are present in spleens of mice 150 days or more following an infection with Brucella abortus. The development of primary plaques in mice long after antigenic challenge is an uncommon phenomenon, unlike the plaque formation (PF) induced by a non-living antigen. The mechanism of this persistent PF has been now investigated in light of a prolonged persistence of the corresponding antigen in tissues. Living E. coli, inoculated in massive dose into mice, survived in their organs for a brief time, while concomitantly PFC disappeared by day sixteen. Infection with B. abortus, in contrast, induced persistent presence of bacteria in the organs of inoculated mice and stimulated long lasting plaque formation. Only direct plaques were found during all stages of infection. Repeated inoculations of dead B. abortus also induced continuous production of primary plaques, whereas an interval in supply of the antigen resulted in disappearance of PFC. Rifampin (40 mg/kg) eliminated bacteria from the treated mice, which resulted in the disappearance of primary PFC. It seems likely that long lasting PF in B. abortus infected mice is connected with a constant antigenic stimulus operating in the carrier state.

Animals↗
PubMed1983

The pathogenesis of synergistic lung damage in mice by an environmental irritant (H2SO4) and particulate antigen.

Daily inhalation by mice of an environmental irritant (H2SO4) followed by consequent respiratory immunization with a particulate antigen (sheep red blood cells, SRBC) induced severe interstitial pneumonitis. Inhalation of H2SO4 per se resulted in accumulation of i.v. injected globulin in the lungs of mice, without significant change in lung weight. In addition, when marker colloidal carbon particles were injected i.v. following H2SO4 inhalation, the carbon was rapidly trapped in the capillary wall in the lungs. Homologous anti-SRBC serum instilled into the respiratory tract followed by subsequent SRBC inhalation produced inflammation and injury similar to that generated by H2SO4 in combination with particulate antigen. It is postulated that following irritant inhalation, the permeability of alveolocapillary membranes increases, so that immune complexes formed by pre-existing circulating antibodies and inhaled antigen can initiate subsequent lung injury.

Animals↗
PubMed1983

The relative roles of MHC and non-MHC antigens in bone marrow transplantation in rats. Graft acceptance and antigenic expression on donor red blood cells.

In order to investigate the influence of MHC and non-MHC genes in bone marrow transplantation, various combinations of congenic and inbred strains of rats were used as donors and recipients. A standard regimen of busulfan and cyclophosphamide treatment was used to condition the recipients. The resultant survival patterns of the animals indicated that: (1) a difference across the entire RT1 (MHC) complex is sufficient for the induction of fatal graft-versus-host disease (GVHD) in 100% of the engrafted animals; and (2) the blood group antigens RT2 and RT3, which are controlled by non-MHC genes, do not cause bone marrow graft rejection or GVHD. There were sequential changes of expression in surface alloantigens on the red cells in different donor-recipient combinations without other hematologic changes in the busulfan-cyclophosphamide conditioned bone marrow chimeras.

Acute Disease↗
PubMed1983

Prolongation of skin graft survival across different genetic barriers in rats with cyclosporine--and its potentiation by Bordetella pertussis vaccine.

Skin allografting was performed in rats treated with cyclosporine using strain combinations that differed across the RT1.A (class I) or RT1.B (class II) loci of the major histocompatibility complex (MHC) or across non-MHC loci. Injection of cyclosporine (20 mg/kg) for 14 consecutive days was followed by prolonged acceptance (MST = 67 days) of the skin allografts. Bordetella pertussis vaccine potentiated the effect of cyclosporine, and the synergistic effect of the vaccine occurred only when it was given before grafting. The cyclosporine given for 14 days with or without B pertussis failed to prolong second-set skin grafts. Production of hemagglutinating antibodies in cyclosporine-treated animals was completely suppressed when the skin grafts were in place, and it occurred to a much lesser extent following rejection, as compared with untreated animals. The cyclosporine did not, however, influence the antibody response following second set skin graft rejection. A system in which rats were treated for only 6 days with cyclosporine was developed in order to test the effects of disparities at different histocompatibility loci on the response to cyclosporine, because this regimen gave a marginal, but significant, prolongation of skin grafts across a full RT1 (MHC) difference. There was a differential effect of cyclosporine treatment depending upon the genetic differences involved: a skin graft across an RT1.A (class I) difference was indefinitely prolonged, one across an RT1.B (class II) or RT1.AB difference was slightly prolonged (9 to 12 days and 12.5 to 16.5 days, respectively) and a graft across non-MHC differences was not affected. Hence, the immunosuppressive effects of cyclosporine on skin graft rejection appear to depend upon the genetic disparities between donor and recipient. Exploitation of this finding may lead to the design of more effective, multidrug protocols for the treatment of rejection that would have fewer deleterious side-effects.

Animals↗
PubMed1982

Mitochondrial and nuclear mutagenicity of ellipticine and derivatives in the yeast Saccharomyces cerevisiae.

Haploid strains of the yeast Saccharomyces cerevisiae were tested for their sensitivity to ellipticine and nine derivatives; some of them exhibiting antitumor properties. Different mutagenic properties of ellipticines are described. Charged ellipticines, which were ineffective in Ames' bacterial assay, were found to be potent inducers of the mitochondrial p- mutation: induction proceeded even in the absence of growth. Uncharged ellipticines increased mitochondrial antibiotic resistance mutations, whereas charged derivatives decreased them. Ellipticine derivatives enhanced, reduced, or did not change the reversion frequencies of nuclear auxotrophic markers. The result depended on the strain being tested: no structure-effect relationship existed. As some ellipticine derivatives were mutagenic in Saccharomyces cerevisiae despite being ineffective in Ames' assay, multiple tests should be used to check that chemotherapeutic drugs are devoid of mutagenic properties.

Alkaloids↗
PubMed1982

Effects of gamma aminobutyric acid (GABA) and muscimol on endocrine pancreatic function in man.

The high concentrations of gamma aminobutyric acid (GABA) in the pancreatic islets and the neurotransmitter role played by this amino acid in the central nervous system, make it plausible that GABA also intervenes in the control of endocrine pancreatic function. In 12 normal subjects, a single oral dose of 5 or 10 g GABA, as compared to placebo, caused a significant (p less than 0.01) and dose-dependent (p less than 0.01) increase of plasma levels of immunoreactive insulin, C peptide and glucagon, without affecting plasma glucose concentration. By contrast, in 15 additional subjects, a single oral dose of 5 mg muscimol, a specific GABA receptor agonist, did not consistently influence the above parameters. Although the lack of effects of muscimol might indicate that the action of GABA is not mediated through specific receptors, the results with GABA suggest that this amino acid plays a specific role in the regulation of endocrine pancreatic function.

Adolescent↗
PubMed1981

Ataxia telangiectasia with evolution of monosomy 14 and emergence of Hodgkin's disease.

A young woman, with ataxia telangiectasia (AT) had a chromosomally abnormal T-lymphocyte clone detected at 23 years of age. This clone showed nonrandom loss of chromosome # 14, a karyotypic abnormality not previously described in AT. Eighteen months later, evolution of the monosomic clone was noted; the karyotype of this latter clone was 45,XX,-14,del(6) (q21). The patient died of Hodgkin's disease of mixed cellularity type, Stage IIIB, a few months later. A striking histological features of a lymph node biopsy was the presence of numerous epithelioid histiocytes. The patient's paternal first cousin also suffers from AT.

Adult↗
PubMed1981

Differentiation and myelination of transplanted mouse dorsal root ganglia.

Dorsal root ganglia from newborn mice develop and myelinate following transplantation under the kidney capsule of adult syngeneic mice. The transplanted dorsal root ganglia in the subcapsular environment developed more rapidly and formed more abundant myelin than comparable ganglia in an in vitro culture.

Aging↗
PubMed1981

Ellipticine, 9-hydroxyellipticine, and 9-hydroxyellipiticinum: some biochemical properties of possible pharmacologic significance.

Ellipticine, 5,11-dimethyl-(6H)-pyrido-(4,3,b)-carbazole (NSC 71795) is a potent cytotoxic and antitumor agent. Several of its derivatives share these properties and nine hydroxylated compounds are even more potent. 2-Methyl-9-hydorxyellipticinium (NSC 264-137) has thus recently been shown to display some therapeutic effectiveness in human breast cancers. The biochemical mechanism of this action is discussed in this paper. DNA has been implied as the target of ellipticine and some derivatives; however, these drugs do not break DNA in cultured L1210 cells. Moreover, several other biochemical constituents are able to bind these compounds in vitro as efficiently as DNA. In this paper the interactions between ellipticine and some of those derivatives and (a) ascitic phospholipids monolayers and (b) cytochrome P450 microsomal proteins are studied and discussed. Finally, the hypothesis that the nonhydroxylated ellipticine derivatives might be better cytotoxic agents because they can be oxidized and generate free radical species through a monovalent electron transfer process is presented. This hypothesis is supported by experiments carried out on the oxidation of 9-hydroxyellipticine and 2-methyl-9-hydroxyellipticine by peroxidases.

Alkaloids↗