Biomedical subjects

A Romero

Publications and source records attributed to A Romero.

At least 109 records · Page 6Linked to original sources

PubMed1997

Effect of ebrotidine on ethanol-induced gastric mucosal damage in the rat. Comparative study with other H2-receptor antagonists.

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]ethyl ] amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) is a novel H2-receptor antagonist with additional gastroprotective effect. The gastroprotective effect of oral doses of ebrotidine against ethanol-induced mucosal damage in female rats was compared with the effect of cimetidine, ranitidine and famotidine. Macroscopically, ebrotidine showed dose-dependent inhibition of the lesion, with significant differences from that of controls at doses of > or = 12.50 mg/kg (ED50 was 26.54 mg/kg). None of the other drugs tested showed gastroprotective effect under the same conditions. The histopathological study revealed significant reduction in the number of deep and superficial ulcers in ebrotidine-treated animals. The gastroprotective effect of ebrotidine is patent even in the presence of indometacin suggesting that prostaglandins play a rather negligible role in gastroprotective action. These results suggest that ebrotidine may be more useful than the classically known H2-antagonists in the treatment of peptic ulcers.

Animals↗

PubMed1997

Study on the increment of the amount of gastric mucus in rats after repeated-dose administration of ebrotidine.

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]ethyl ] amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) is a novel H2-receptor antagonist that also exhibits a potent gastroprotective action against ethanol damage. This study was designed to ascertain under physiological conditions the effect of ebrotidine on the secretion of gastric mucus, probably the main component of the mucosal barrier. Two groups of 20 rats each were given a daily oral dose of 10 or 35 mg/kg ebrotidine, respectively, for 17 days. A third group of 20 rats was used as a control. Once the administration period had concluded, the animals were killed and their stomachs were removed and processed by the periodic acid-Schiff (PAS) histochemical method, selective for mucopolysaccharides. PAS-positive areas exhibited a characteristic carmine colour, allowing morphometric study by computerized image analysis. All the histological sections studied were from the same region of the stomach. A significant increase in the PAS-positive area corresponding to glandular mucus was found in all treated groups. This action is consistent with an increased secretion of mucopolysaccharides and represents one of the main mechanisms of the cytoprotective action of ebrotidine.

Animals↗

PubMed1997

Acute toxicity studies of ebrotidine.

The acute toxicity of two formulations of ebrotidine (N-[N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) was studied in rats and mice by different routes of dosing: oral and intraperitoneal routes in rats and mice (suspension), intravenous and oral routes in mice and intravenous route in rats (injectable solution). LD50 values for the oral route were indeterminable in all cases. For the intraperitoneal route. LD50 values were 316 mg/kg (rat) and 366 mg/kg (mouse), and for the intravenous route LD50 values were 100 mg/kg (rat) and 107 mg/kg (mouse).

Administration, Oral↗

PubMed1997

Subacute toxicity of ebrotidine in rats and dogs.

Subacute toxicity studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl] thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) were performed in Spragu-Dawley rats and Beagle dogs. Both animal species were administered with the same dose levels (50, 200 and 500 mg/kg) for 4 and 7 weeks, respectively. In a previous 4-week subacute toxicity study in the rat, ranitidine and cimetidine at 500 mg/kg were used as reference drugs. The results indicated that ebrotidine was well tolerated at 50 mg/kg, while there were dose-related effects at 200 and 500 mg/kg. Probably due to its pharmacokinetics, ebrotidine was more toxic in dogs than in rats, since the most severe effects were the death or sacrifice in extremis of two dogs from the high dose group which had undergone rectal prolapse, while no deaths occurred in the rats. The changes that were very likely related to treatment (500 mg/kg) were a lower weight in both species, a slight decrease of hematocrit and red blood cells in rats, single increments of transaminases, alkaline phosphatase and lactate dehydrogenase in dogs (some animals of the 200 mg/kg dose group were also affected) and a higher liver weight. These effects with a few exceptions were found to be common to cimetidine and ranitidine.

Animals↗

PubMed1997

Chronic toxicity of ebrotidine in rats and dogs.

The results obtained in the chronic toxicity studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) by oral route in rats and in Beagle dogs are reported. Rats were administered for 6 months and dogs for 12 months. The doses were 50, 200 and 500 mg/kg in rats and 50, 200 and 400 mg/kg in dogs. The dose of 400 mg/kg was reduced to 350 mg/kg after 3 months of treatment, due to its toxicity. The effects probably related to the administration of ebrotidine were as follows: three dogs from the high dose group died after 3, 4.5 and 8 months of treatment (in rat there was no mortality); occult blood in faeces; lower weight gain in the high dose group (in rats only females were affected); lower food consumption in rats from the high dose group (and also females from the middle dose group); reduction of erythrocyte count and packed cell volume, only in rats and at the end of the study; alkaline phosphatases increment in rats and dogs; proteinemia decrease in rats; and a tendency to decrease in the testicular weight, which was not statistically significant (p > 0.05). The only histopathological changes observed were moderate erosions or ulcerations in the intestinal mucosa of some dogs from the high dose group. These effects coincide with those published for other competitive H2-receptor inhibitors. The maximum toxic effect-free level was 50 mg/kg for both rats and dogs, which provides a wide safety margin with respect to the therapeutic dose.

Animals↗

PubMed1997

Toxicity of ebrotidine on reproduction. Toxicity on fertility and general reproductive performance, embryo-fetal toxicity and peri- and postnatal toxicity.

Reproduction toxicity studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl] thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) are presented in this paper. Rats dosed with 50, 200 and 500 mg/kg p.o. of ebrotidine were used for the fertility and peri- and postnatal toxicity studies, and rabbits dosed with 25, 100 and 250 mg/kg and rats dosed with 50, 200 and 500 mg/kg of ebrotidine were used for the embryotoxicity study. The fertility study was designed in accordance with a 2-generation study protocol. The results showed that ebrotidine did not interfere with male and female gametogenesis, fertility, organogenesis, postnatal development and lactation in F0 or F1 animals. Only general or non-specific effects were attributed to treatment, such as a lower weight gain in parents or fetuses in rats, or a somewhat slower bone calcification in rats, which was shown to be recoverable and had no peri- or postnatal repercussions. Neither did the fertility study reveal a possible longer duration of gestation nor did the peri- and postnatal study show a lower weight of the F1 offspring. There was only an increase in rabbit embryonic mortality, probably related to some cases of abortion at the high dose. No potential antiandrogenic effect on the reproductive function has been found. Among the different doses used in both animal species, the maximum toxic effect-free dose was that of 25 mg/kg.

Abnormalities, Drug-Induced↗

PubMed1997

Genotoxicity studies on ebrotidine.

Five genotoxicity studies on ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio] ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542), including at least four of the battery of tests recommended by toxicological regulatory guidelines for new drugs, were conducted. These tests were the Ames test for determination of bacterial gene mutations, sex-linked recessive lethal mutation test in Drosophila for gene mutations in eukaryotic systems, in vitro chromosome aberration test and micronucleus test for evaluation of structural and numerical aberrations, and sister chromatid exchange frequency test for assessment of non-specific damage to chromatin. Negative and positive controls were used in all the experiments. The effects were investigated in the absence or presence of metabolic activation by S-9 microsomal fraction from rat liver homogenate. A dose range toxicity study was also performed to determine the dosage levels or concentrations to be tested for the assessment of genotoxic effects. None of the tests showed a significant increase in the genotoxic parameters, both in vitro and in vivo in somatic or germ cells. It is, therefore, concluded that ebrotidine has not caused mutagenic or clastogenic effects in any of the experimental systems tested.

Animals↗

PubMed1997

Carcinogenicity studies on ebrotidine.

The results from two carcinogenicity studies on ebrotidine (N-[2-(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) conducted in mice and rats are reported. Oral doses of 50, 200 and 500 mg/kg were administered to mice for 18 months and 50, 200 (150), 300 and 500 mg/kg were administered to rats for 24 months. The study design was prepared according to EEC guidelines, and the recommendations by the International Agency for Research on Cancer were used for the statistical analysis of data. Weekly palpations were made along the course of studies and general parameters were monitored. The only effects attributed to ebrotidine administration were a slight decrease in the survival rate of female mice given the 500 mg/kg dose and a lower weight gain in rats of both sexes. The histopathological data revealed that lipoid pneumonia and kidney calculi are more frequent in rats treated with doses of 500 and 300 mg/kg. No increment in the spontaneous occurrence of tumours or significant presence of tumours in treated animals differing from that in control animals was observed, and a decrease in the time required for their onset that could be related to ebrotidine was not observed either. There were no differences in hyperplastic and/or dysplastic changes between treated and control animals. Therefore, it is deduced that ebrotidine does not induce neoplastic or preneoplastic effects in rats or mice even at doses of 500 mg/kg, at which some general toxicity effects are seen.

Animals↗

PubMed1997

Study of the population of antral G-cells and enterochromaffin-like cells in the rat and mouse gastric mucosa after long-term treatment with ebrotidine.

The potential effect of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene]amino]-4-thiazolyl]methyl]thio]ethyl ] amino)methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) on two types of enteroendocrine cell populations in the gastric mucosa, antral G-cells and enterochromaffin-like cells, was investigated. The study of the population of antral G-cells was performed in a group of male rats treated with ebrotidine 500 mg/kg p.o. for 60 days; a control group receiving 10 ml/kg of an aqueous agar solution was used. A PAP (peroxidase-antiperoxidase) system-associated antigastrin immunohistochemical method was used for cell identification. The population of enterochromaffin-like cells was assessed by quantifying the density of argyrophilic cells in mouse gastric mucosa after an 18-month treatment with ebrotidine 500 mg/kg. Grimelius silver staining method was used for cell identification. In both studies, cell count was performed using a light microscope at 400 x magnification and cell density was calculated by computer-assisted image analysis. Compared to control, ebrotidine did not cause any significant differences in the cell density of the populations studied.

Animals↗

PubMed1997

Comparative study of plasma gastrin levels in rats after two months of ebrotidine administration.

Four groups of male rats were orally administered for 60 days with daily doses of ebrotidine (N-[(E)-[[2-[[[2-[(diaminoethylene) amino]-4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo- benzenesulfonamide, CAS 100981-43-9, FI-3542) (500 mg/kg), ranitidine (500 mg/kg), cimetidine (500 mg/kg) and omeprazole (43.5 mg/kg). A fifth group received no treatment and was used as control. The curve of gastrinemia was obtained on days 1, 15 and 60 of administration. On each of these days gastrinemia was assessed at 0, 1, 5, 8, and 24 h on day 1, and 1, 5, 8, 10 and 24 h on days 15 and 60. The purpose of this study was to compare the plasma gastrin level profile in association with the administration of test drugs on days 1, 15 and 60 of treatment. The results showed a significant difference in the duration of hypergastrinemia of H2-receptor antagonists as compared to proton pump blockers. Although peak plasma gastrin levels were attained for all products between 5 and 8 h after day 1 of administration, H2-receptor antagonists, unlike omeprazole, achieved recovery of gastrin baseline levels within 24 h. On days 15 and 60 of ebrotidine, treatment, plasma gastrin levels returned to normal range at 5 and 8 h after administration, respectively. After ranitidine and cimetidine, hypergastrinemia was still present at this time, but normal levels were attained before 24 h. With omeprazole plasma gastrin levels did not return to normal range within 24 h after each administration, and a cumulative effect occurred during treatment. The omeprazole treated group showed the highest and more sustained plasma gastrin levels. It was concluded that ebrotidine was the antisecretory agent with the lowest hypergastrinemic effect during long-term treatment. With ebrotidine daily baseline gastrin levels were more rapidly recovered after each administration.

Animals↗

PubMed1997

Calcitonin gene-related peptide immunoreactivity in adult mouse lung.

Calcitonin gene-related peptide (CGRP) is a 37 amino acid peptide coded by the calcitonin gene that is produced by thyroid C cells and medullary carcinoma. It is also widely distributed in neurons and endocrine cells throughout the body. The presence of CGRP in the lungs suggests that this peptide exerts important regulatory actions at this level, and it can act like a neuroregulator released both from nerve terminals and neuroendocrine (NE) cells. To understand the role of CGRP in the lung, it is important to explore its localization in different species. In this paper, we analyse the presence and localization of CGRP in the adult mouse lung using an immunocytochemical staining method. Our results show a widespread distribution of this peptide in isolated neuroendocrine cells and neuroepithelial bodies (NEBs), as well as in nerve fibres distributed in many areas of the lung, including bronchi and bronchioli. These fibres are in close contact with epithelium, neuroendocrine cells and smooth muscle. In addition, some immunostained nerve cell bodies and immunoreactive intrinsic ganglion cells can be shown. CGRP has been previously demonstrated in the mammalian lung using immunocytochemistry. To the best of our knowledge, this is the first time that CGRP has been immunocytochemically demonstrated in the mouse lung both in NE cells, NEBS, ganglion cells and in nerve fibres which are related to neuroendocrine cells.

Animals↗

PubMed1997

Presence and distribution of 5HT-, VIP-, NPY-, and SP-immunoreactive structures in adult mouse lung.

A large number of biologically active substances have been identified and characterised in the respiratory tract of several mammals. These substances (amines and peptides) exert important regulatory influences on respiratory functions, and they act as neurotransmitters/neuromodulators, both being released from nerve terminals as neuroendocrine cells. However, these substances can also have other effects which suggest a paracrine action. Thus, to understand the role of amines and peptides in the lung, it is important to explore their localisation in different species. By using immunocytochemical staining methods we have studied the morphology and distribution of serotonin-, Substance P-, neuropeptide Y- and VIP-like immunoreactivity in the adult mouse lung. Moreover a pretreatment with colchicine, pargyline and 5-hydroxytryptophan as staining enlargement method was made. A widespread distribution of isolated endocrine cells and neuro-epithelial bodies containing 5HT-like immunoreactivity was recorded within the lung. NPY-like immunoreactive nerve fibres were localised in the airway smooth muscle and surrounding the blood vessels. VIP-like immunoreactivity was revealed in single cells as well as in some nerve fibres and ganglia around the blood vessels and in the bronchial smooth muscle. SP-like IR was observed in nerve fibres located in the smooth muscle of the airways, surrounding bronchi and bronchioli but not next to the intrapulmonary blood vessels. Their localisation both in cells and nerve fibres of the respiratory system suggests that they play a role in the regulatory function of the mouse respiratory tract, exerting their influence by endocrine, paracrine, neurosecretory pathways or a combination of all of these.

Animals↗

PubMed1996

p53 and PCNA expression in advanced colorectal cancer: response to chemotherapy and long-term prognosis.

In a series of 71 patients with advanced colorectal cancer treated with biochemically modulated 5-fluorouracil (5-FU) and methotrexate (MTX), we investigated the relationship between the proliferating-cell nuclear antigen (PCNA) (PC10) and p53 (Pab1801) primary-tumor immunohistochemical expression with respect to clinical response and long-term prognosis. Nuclear p53 expression was demonstrated in 44% of samples (any number of positive tumor cells) while all tumors showed a certain degree of PCNA immunostaining. PCNA immunostaining was correlated with histopathologic grade and p53 expression, while p53 was not correlated with any of the parameters considered. The probability of clinical response to biochemically modulated 5-FU was independent of p53 and PCNA expression. p53 expression (all cut-off values) was not associated with short- or long-term clinical prognosis, whereas patients with higher PCNA primary-tumor expression showed longer survival from treatment and survival from diagnosis, according to univariate and multivariate analysis, particularly in the sub-set of colon-cancer patients. We conclude that the clinical response of advanced-colorectal-cancer patients to biochemically modulated 5-FU and MTX cannot be predicted by PCNA and p53 primary-tumor expression, but high PCNA expression appears to be independently related to long-term prognosis.

Adult↗

PubMed1996

X-ray structure of native full-length human fibroblast-growth factor at 0.25-nm resolution.

Acidic fibroblast-growth factor (aFGF) is one of the typical members of a group of nine polypeptides of relatively similar amino acid sequence known as the fibroblast-growth-factor family of proteins. Widely distributed throughout the organism, fibroblast-growth factors seem to be involved in numerous physiological processes ranging from control of cell proliferation and differentiation to modulation of animal behaviour and arterial blood pressure. This wide assortment of biological activities explains their involvement in numerous pathologies. Instability and low yields of the purified protein have precluded high-resolution structural studies of the physiological form of aFGF. Nevertheless, modifications introduced recently into the synthesis and purification procedures of this protein have allowed preparations of samples that, as shown here, are reliable substrates to obtain crystals suitable for X-ray-diffraction studies. These analyses have allowed us to elucidate the three-dimensional structure of the physiological form of human aFGF by molecular-replacement methods, from the previously reported structure of a shortened form of bovine aFGF that was stabilized by point-directed mutagenesis. The structure was refined at a resolution of 0.25 nm to an R factor of 20.4% for 13,109 reflections between 0.6 nm and 0.25 nm, with rmsd of 1.1 pm and 1.9 degrees from ideal bond lengths and bond angles, respectively. Human aFGF folds according to a beta-trefoil topology. This fold consist of six beta-strand pairs. Three of them form a six-stranded beta-barrel structure that is capped at one end by the other three pairs arranged in a triangular array. The N-terminus of aFGF up to residue Pro19 appears flexible in the structure and does not specifically interact with the rest of the molecule.

Amino Acid Sequence↗

PubMed1996

Crystal structure of flavodoxin from Desulfovibrio desulfuricans ATCC 27774 in two oxidation states.

The crystal structures of the flavodoxin from Desulfovibrio desulfuricans ATCC 27774 have been determined and refined for both oxidized and semi-reduced forms to final crystallographic R-factors of 17.9% (0.8-0.205-nm resolution) and 19.4% (0.8-0.215-nm resolution) respectively. Native flavodoxin crystals were grown from ammonium sulfate with cell constants a = b = 9.59 nm, c=3.37nm (oxidized crystals) and they belong to space group P3(2)21. Semireduced crystals showed some changes in cell dimensions: a = b = 9.51 nm, c=3.35 nm. The three-dimensional structures are similar to other known flavodoxins and deviations are found essentially in the isoalloxazine ring environment. Conformational changes are observed between both redox states and a flip of the Gly61-Met62 peptide bond occurs upon one-electron reduction of the FMN group. These changes influence the redox potential of the oxidized/semiquinone couple. Modulation of the redox potentials is known to be related to the association constant of the FMN group to the protein. The flavodoxin from D. desulfuricans now studied has a large span between E2 (oxidized --> semiquinone) and E1 (semiquinone --> hydroquinone) redox potentials, both these values being substantially more positive within known flavodoxins. A comparison of their FMN environment was made in both oxidation states in order to correlate functional and structural differences.

Amino Acid Sequence↗

PubMed1996

Different architecture of the combining site of the two chicken galectins revealed by chemical mapping studies with synthetic ligand derivatives.

The detailed comparison of the carbohydrate-binding properties of related galectins from one organism can be facilitated by the application of an array of deliberately tailored methyl beta-lactoside derivatives. Focusing on chicken due to its expression of two galectins as a model for this approach, the combining-site architecture of the lectin from adult liver (CL-16) is apparently homologous to that previously observed for bovine galectin-1 (Solís, D., Jiménez-Barbero, J., Martín-Lomas, M., and Díaz-Mauriño, T. (1994) Eur. J. Biochem. 223, 107-114). Besides preservation of the key interactions and minor differences, the lectin from adult intestine (CL-14) is able to accommodate an axial HO-3 at the glucose moiety. Homology-based modeling enabled us to tentatively attribute the observed differences to a slightly different orientation of pivotal side chains in the binding pocket due to distinct substitutions of amino acid residues in the variable region within the carbohydrate-recognition domain. Thus, the results suggest overlapping but distinct ranges of potential ligands for the two chicken lectins and provide new information on their relationship to mammalian galectins. The described approach is suggested to be of relevance to design pharmaceuticals with enhanced selectivity to a certain member within a family of related lectins.

Amino Acid Sequence↗

PubMed1996

Crystallization and preliminary X-ray diffraction analysis of boar seminal plasma spermadhesin PSP-I/PSP-II, a heterodimer of two CUB domains.

Boar spermadhesin PSP-I/PSP-II (M(r) 29 000-30 000), a non-covalent heterodimer of two CUB domains, was crystallized in two crystal forms. Complete diffraction data sets for hexagonal (space group P6(1,5)22) and trigonal (space group P3(1,2)21) crystals have been collected up to 2.9 and 2.5 angstrom resolution, respectively. Cell constants of the hexagonal and trigonal crystal forms are a=b=87.2 angstrom, c=152.4 angstrom, and a=b=96.2 angstrom, c=70.8 angstrom, respectively. The calculated packing parameters (Vm) are 2.8 and 3.2 angstrom(3)/DA for the hexagonal and trigonal crystal forms, respectively, indicating that, in both cases, the asymmetric unit is constituted by one PSP-I/PSP-II heterodimer. This paper reports the first crystals of a protein built up by a CUB domain architecture.

Amino Acid Sequence↗

PubMed1996

A procedure for the large-scale isolation of major bovine seminal plasma proteins.

A method for the stepwise purification of bovine seminal plasma proteins aSFP, PDC-109, TIMP-2, RNAse, and BSP-30K/PDC-109 complex is presented. It is based on the use of nondenaturing, classical chromatographic procedures. The isolation protocol is reproducible, inexpensive, easy to carry out in a common laboratory, and yields large amounts of pure proteins for biochemical and structural studies.

Amino Acid Sequence↗