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Biomedical subjects

M Costa

Publications and source records attributed to M Costa.

At least 361 records · Page 20Linked to original sources
PubMed1989

The duration of pituitary suppression by means of intranasal gonadotropin hormone-releasing hormone analogue administration does not influence the ovarian response to gonadotropin stimulation and success rate in a gamete intrafallopian transfer (GIFT) program.

The aim of the study was to compare the ability to prevent endogenous luteinizing hormone interferences, ovarian response, and success rate between two groups of patients undergoing GIFT procedures and treated with the same stimulatory protocol but with a different timing in the administration of the gonadotropin hormone-releasing hormone analogue (GnRH-a). The former underwent a concomitant administration of gonadotropin and analogue; the latter started stimulation only after the achievement of complete hypogonadotropinism. The analogue was always given intranasally and stimulation was identical in the two groups. Our results showed that (1) prevention of premature luteinization is obtained with both approaches and (2) no significant difference in terms of length of stimulation, gonadotropin doses, ovarian response, and success rate was recorded between the two groups.

Administration, Intranasal↗
PubMed1989

Migration of the myoelectric complex after interruption of the myenteric plexus: intestinal transection and regeneration of enteric nerves in the guinea pig.

The effects of surgical interruption of the myenteric plexus (myectomy), extrinsic denervation of a length of small intestine, or transection and reanastomosis of the intestinal wall on migration of phase III of the migrating myoelectric complex was studied in guinea pigs. In addition, the recovery of phase III migration and the regrowth of intestinal nerves and muscle across the reanastomosis was studied at various times up to 60 days after surgery. At 6-9 days after surgery, phase III did not migrate past the myectomy during 50%-60% of recorded migrating myoelectric complexes and transection and reanastomosis of the intestinal wall blocked aboral progression of phase III in 90% of cases. Extrinsic denervation did not alter phase III migration through the denervated segment. Phase III migration past the reanastomosis recovered with time after surgery; 80% recovery occurred by 60 days after surgery. Immunoreactivities for vasoactive intestinal peptide, gastrin-releasing peptide, and somatostatin were used as markers for intestinal nerves that were cut by transaction. Immunoreactivities for vasoactive intestinal peptide and gastrin-releasing peptide are contained in myenteric neurons that project in an oral to anal direction to other myenteric ganglia and to the circular muscle. Immunoreactivity for somatostatin is contained in nerve fibers projecting aborally to other myenteric ganglia. At 7-15 days after surgery, there were accumulations of immunoreactivities for vasoactive intestinal peptide, gastrin-releasing peptide, and somatostatin in nerve fibers on the oral side of the reanastomosis, but nerve fibers containing these peptides were not observed in myenteric ganglia or circular muscle close to the anal edge. At 23-28 days, immunoreactivities for vasoactive intestinal peptide, gastrin-releasing peptide, and somatostatin nerve fibers were traced across the reanastomosis and nerve terminals were detected in ganglia and muscle close to the lesion on the anal side. Nerve fibers traversed the lesion in all cases at 57-60 days and vasoactive intestinal peptide-, gastrin-releasing peptide-, and somatostatin-immunoreactive nerve terminals were detected in the first two to three rows of myenteric ganglia on the anal side. Regrowth of intestinal muscle followed a similar time-course to that observed for nerves. These data suggest that interruption of the myenteric plexus alone does not completely block phase III migration. In addition, recovery of phase III migration past a reanastomosis is associated with a restoration of both nervous and mechanical connections.

Animals↗
PubMed1989

An electrophysiological comparison of substance P-immunoreactive neurons with other neurons in the guinea-pig submucous plexus.

Intracellular microelectrodes containing the dye Lucifer yellow CH were used to record from nerve cells of ganglia in isolated preparations of submucosa from the guinea-pig small intestine. The electrophysiological properties of the neurons were investigated by passing intracellular current pulses and by stimulating nerve strands that connect with the ganglia. Following each electrophysiological investigation, the fluorescent dye was injected into the neuron by passing hyperpolarizing currents through the electrode. The preparations were fixed and processed for substance P (SP) immunohistochemistry. When impaled neurons were not immunoreactive for SP the preparations were processed first for vasoactive intestinal peptide immunoreactivity and then for neuropeptide Y immunoreactivity. Data from neurons reactive for either of these peptides were pooled for comparison with the data from SP-immunoreactive neurons. Nerve cells that were immunoreactive for SP were usually multipolar, had broad action potentials (half width 2.6 ms compared with 1.5 ms for other submucous neurons) and lower input resistances than other submucous neurons. Only a minority (6 of 18) had demonstrable fast excitatory synaptic inputs. When such excitatory synaptic inputs were observed, these did not initiate action potentials. Thus, the SP-immunoreactive neurons were readily distinguishable from other submucous neurons. It is concluded that these neurons are likely to be sensory.

Animals↗
PubMed1989

Screening in mice of some medicinal plants used for analgesic purposes in the state of São Paulo. Part II.

Seventeen medicinal plants used popularly in Brazil for their reputed analgesic properties were tested in mice by the writhing and tail flick methods. All extractions were made in 50% aqueous ethanol at low temperatures. The oral dose administered was always 1 g extract/kg. Significant effects in both tests were produced by Lippia alba, Piper abutiloides, Piper cincinnatoris, Piper lindbergii and Tillandsia usneoides.

Analgesics↗
PubMed1989

Immunological detection of DNA-protein complexes induced by chromate.

A select group of non-histone proteins becomes complexed to DNA after Chinese hamster ovary (CHO) cells are treated with potassium chromate. The most abundant complexed protein has a mol. wt of approximately 45 kd and is thought to be actin. An antiserum to the chromate-induced DNA-protein complexes (DPCs) was prepared to facilitate the study of these complexes. Rather than detecting the predominant silver-stained proteins of DPCs described in an earlier study, this antiserum reacts primarily with an acidic 95-kd protein (p95) that does not silver stain. The antiserum can be used routinely to assay for the induction of p95-DNA complexes produced by chromate and perhaps by other carcinogens. Immunofluorescent staining of CHO cells and immunoblotting of cell fractions show the reactive antigens are within the cell nucleus. Blotting experiments with the antiserum indicate the chromate-induced p95-DNA complex dissociates in the presence of 2-mercaptoethanol, suggesting similarity to the DPCs formed by carcinogenic platinum compounds. A reduced species of chromium (probably Cr3+) may form DPCs by binding to the nitrogen, oxygen or sulfur atoms of proteins and DNA. These results illustrate the usefulness of immunological detection methods to study specific DNA-protein interactions induced by carcinogens. The possible relevance of DPCs in the carcinogenic process is discussed.

Animals↗
PubMed1989

Perspectives on the mechanism of nickel carcinogenesis gained from models of in vitro carcinogenesis.

This article briefly reviews the approach taken to understand the mechanism of nickel-induced neoplastic transformation. The initial phases of the studies were focused on particulate nickel compounds and on the regulation of phagocytosis of nickel compounds by cells undergoing transformation. The particulate nickel compounds most potent in inducing cell transformation were selectively phagocytized by cells, whereas those that were not active were not phagocytized. The intracellular fate of phagocytized nickel sulfide particles is discussed as well as the interaction of nickel with chromatin. Phagocytized nickel sulfide particles were dissolved in the cytoplasm of cells by the acidification of vacuoles containing phagocytized particles. Nickel ions released from the phagocytized particles produced selective damage in heterochromatin. The selective effects of nickel on heterochromatin are also discussed and related to its mechanism of carcinogenesis.

Animals↗
PubMed1989

Toxicity and carcinogenicity of nickel compounds.

The toxicity and carcinogenicity of nickel compounds are considered in three broad categories: (1) systemic toxicology, (2) molecular toxicology, and (3) carcinogenicity. The systemic toxicity of nickel compounds is examined based upon human and animal studies. The major organs affected are discussed in three categories: (1) kidney, (2) immune system, and (3) other organs. The second area of concentration is molecular toxicology, which will include a discussion of the chemistry of nickel, its binding to small and large molecular weight ligands, and, finally, its cellular effects. The third major area involves a discussion of the carcinogenicity and genotoxicity of nickel compounds. This section focuses on mechanisms, using studies conducted in vivo and in vitro. It also includes a discussion of the assessment of the carcinogenicity of nickel compounds.

Animals↗
PubMed1989

Alteration of nickel-binding proteins in nickel-resistant cells.

Proteins from wild-type and nickel-resistant cells (Balb/c-3T3 and B200, respectively) were studied by one- or two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and detected either by standard protein staining or by fluorographic analysis of [63Ni] binding. Wild-type cells contained three major nickel-binding proteins with molecular masses of 68 kDa (p68), 55 kDa (p55), and 48 kDa (p48). The p55 was present in high concentrations in the microsomal fraction, whereas the p68 nickel-binding protein predominated in the cytosolic fraction. We were unable to demonstrate that p48 was localized in any subcellular fraction. Both the p55 and p48 proteins appeared to be present in similar amounts in wild-type and nickel-resistant cell lines, based upon silver staining of two-dimensional gels, yet in the nickel-resistant B200 cells, these proteins could not be visualized by [63Ni] binding. This suggested that if nickel binding to these proteins were important for nickel toxicity, then nickel resistance in the B200 cells would be associated with the observed loss of metal binding to these proteins. In addition to the changes in [63Ni]-binding proteins, the total concentration of a 44 kDa protein was increased in B200 cells, but its ability to bind nickel could not be established due to its rapid degradation. Among the nickel-binding proteins studied, the p55 contained nickel-binding sites that were the most resistant to exchange by excess nickel ions. The microsomal fraction that contained the highest concentration of p55 also had the highest nickel-binding activity when standardized for protein concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Ultrastructural analysis of substance P-immunoreactive nerve fibers in myenteric ganglia of guinea pig small intestine.

Electron microscopic immunocytochemistry has been used to study the distribution and synaptic relationships of substance P (SP)-immunoreactive nerve fibers in ultrathin sections from whole-mount preparations of myenteric ganglia from guinea pig small intestine. At the light microscopic level, myenteric ganglia stained for ultrastructural study contained dense arrays of SP-immunoreactive nerve fibers around and between the neuronal and glial cell bodies. At the electron microscopic level, SP-containing nerve fiber profiles occurred throughout the neuropil of the myenteric ganglia. Both vesicle-containing and nonvesiculated nerve fiber profiles were immunoreactive. The positive vesiculated profiles contained variable proportions of small clear and large granular vesicles. Two-thirds of the vesicle-containing nerve fiber profiles in myenteric ganglia were immunoreactive for SP. Many vesiculated SP-immunoreactive nerve fiber profiles were directly apposed to each myenteric neuron. However, only about 0.6% of these vesiculated profiles formed synapses that showed the ultrastructural specializations of vesicle clustering presynaptically and fuzzy electron-dense material on the postsynaptic membrane. On the other hand, morphologically identifiable synapses with SP-immunoreactivity comprised about half the total number of synapses in the ganglia. SP-immunoreactive synapses were observed on nonvesiculated nerve processes in the periphery of the ganglia and on nerve cell bodies. Most of the axosomatic SP synapses occurred on small neurons that lay either on the surfaces of the ganglia or near the fibers of the internodal strands where they traveled through the ganglia. Both SP-positive and SP-negative nerve cell bodies received SP synapses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Paroxysmal nocturnal hemoglobinuria presenting as acute renal failure].

We report a patient who developed acute renal failure at the first severe hemolytic crisis associated to paroxysmal nocturnal hemoglobinuria. The associated histologic findings on electron microscopy and immunofluorescence are discussed as an insight to possible pathogenic mechanisms.

Acute Kidney Injury↗
PubMed1989

[Antibodies against Hantaan virus and Leptospira in subjects at risk in Rome].

A survey on the prevalence of Hantaan and leptospiral antibodies on mammalogists and rodent control personnel was performed. None of the 66 trappers studied (using IFI ) had detectable Hantaan antibody, while only 2 out of 20 mammalogists presented antibody at low titer (1:32). For leptospiral antibody the microagglutination test (MAT) using live leptospires as antigen was performed. 14 out of 66 trappers, or 21.2 per cent, had antibodies, at titer of 1:50 or more, to various leptospiral serovars: L.icterohaemorrhagiae in 12 cases, L.hardjo in 1 case, L.bratislava in 1 case. On the contrary, none of the mammalogists showed positivity for any of 16 serovars used. The environmental risk factors could justify the high prevalence of leptospiral antibodies in the field workers (trappers), while continuous laboratory contacts with rodents explain the presence of Hantaan virus antibodies in mammalogists .

Agglutination Tests↗
PubMed1989

Analysis of proteins cross-linked to DNA after treatment of cells with formaldehyde, chromate, and cis-diamminedichloroplatinum(II).

The proteins cross-linked to the DNA of cultured Chinese hamster ovary cells after exposure to cis-diamminedichloroplatinum(II) (cis-Pt), chromate, and formaldehyde were compared by two-dimensional (2D) gel electrophoresis, immunoblotting, and centrifugal assays that measured cross-link stability. Chromate and cis-Pt cross-linked seven of the same nonhistone proteins, such as actin, to DNA. In contrast, formaldehyde selectively formed histone-DNA cross-links. Immunoblotting experiments showed that all three chemicals cross-linked a 97-kDa nuclear protein to the DNA despite their different chemical reactivity with DNA and proteins. The chromate- and cis-Pt-induced cross-links were disrupted by thiourea, 2-mercaptoethanol, and EDTA, indicating that the metal could be chemically displaced from the cross-links. The formaldehyde-induced complexes required degradation with DNase 1 for the resolution of histones on 2D gels and were not chemically labile like the metal-induced cross-links. The agents and methodology used here could be applied to the study of additional nuclear proteins that bind or reside near the DNA.

Animals↗
PubMed1989

[Pseudohyponatremia and anion gap changes in multiple myeloma].

Pseudo-hyponatremia is a rare condition characterized by a decrease in plasma sodium concentration associated with a normal or increased effective plasma osmolarity. We present the case of a 62 year old woman with multiple myeloma (IgG) who had a plasma sodium of 84.5 mEq/l (as measured with flame photometry) and an anion gap of -8.8 mEq/l. However, when determined with an ion-selective electrode, plasma sodium was 135 mEq/l. The patient was treated with chemotherapy and did not receive sodium. One week later, plasma sodium--again measured by flame photometry--was 134 mEq/l and the anion gap 4.0 mEq/l. The pathophysiological and clinical aspects of pseudo-hyponatremia and the anion gap are discussed.

Acid-Base Equilibrium↗
PubMed1988

Posterior pattern formation in C. elegans involves position-specific expression of a gene containing a homeobox.

During postembryonic development in C. elegans, posterior-specific pattern formation requires the gene mab-5. Within the posterior body region, mab-5 activity controls epidermal, neuronal, and mesodermal cell differentiation, and also the direction of cell migration. Here, we show that mab-5 RNA is localized in the posterior body region, indicating that mab-5 activity is targeted to posterior cells, at least in part, by a mechanism that operates at the level of mab-5 RNA synthesis or stabilization. We also show that mab-5 contains a homeobox similar to that of the Drosophila Antennapedia gene. This suggests that mab-5 influences cell differentiation and cell migration by regulating gene expression, and clearly demonstrates that genes containing homeoboxes influence global aspects of pattern formation in organisms other than Drosophila.

Amino Acid Sequence↗
PubMed1988

Characterization of mouse cell lines resistant to nickel(II) ions.

BALB/c-3T3 cells have been isolated that are resistant to NiCl2. The degree of resistance is directly dependent upon the NiCl2 exposure concentration and ranges from 6- to 11-fold. Resistance to NiCl2 does not appear to be due to alterations in cellular uptake, since the entry of Ni(II) into wild-type or resistant cells was similar. Resistance does not appear to be due to alterations in metallothionein expression. Resistant cells have a high incidence of heterochromatic abnormalities involving fusions at the centromeres as determined by C-banding and in situ hybridization utilizing a cloned mouse satellite DNA probe. Cells retain nickel resistance for many generations in the absence or presence of NiCl2 selection; however, with time in the absence of NiCl2, the level of resistance decreases. This loss of resistance is associated with a decreased number of centromeric fusions. These results indicate that nickel resistance is involved with changes in heterochromatin and suggest that this effect of nickel on heterochromatin may be important as an early step in nickel carcinogenesis.

Animals↗
PubMed1988

Localized isolated angiitis of the central nervous system associated with primary intracerebral lymphoma.

Isolated angiitis of the central nervous system (IACNS) is a form of granulomatous vasculitis that is confined to the nervous system. A patient with localized IACNS affecting the left internal carotid and posterior cerebral artery adjacent to a primary intracerebral lymphoma of the midbrain along with associated granulomatous inflammation of the dura, leptomeninges, and ependyma of the aqueduct of Sylvius is described. His course was complicated by many neurologic complications before his death. Prednisone and cyclophosphamide were unable to control his disease. More aggressive therapy may be indicated for patients with lymphoproliferative lesions and associated central nervous system (CNS) vasculitis who fail to respond to conventional therapy.

Brain Neoplasms↗
PubMed1988

Quantitative ultrastructural analysis of enkephalin-, substance P-, and VIP-immunoreactive nerve fibers in the circular muscle of the guinea pig small intestine.

The present work was undertaken to determine what proportion of all nerve fibers in the circular muscle of the guinea pig small intestine contain the neuropeptides enkephalin, substance P, and vasoactive intestinal peptide and in which combinations these peptides occur in the fibers. It was envisaged that such an analysis would provide insights into the chemical identity of excitatory and inhibitory nerve fibers that innervate the muscle. Whole-mount preparations from normal and extrinsically denervated gut were labelled with antiserum to the individual peptides or with combinations of antipeptide antisera and processed for electron microscopy. Reactive and nonreactive vesicle-containing nerve fiber profiles were examined and counted in ultrathin sections. Vesicle-containing nerve fiber profiles immunoreactive for enkephalin, substance P, or vasoactive intestinal peptide had similar morphologies in that they all contained variable proportions of small clear and large granular vesicles. In all samples stained for single peptides or combinations of peptides, a small proportion of immunoreactive profiles approached smooth muscle cells to within 15-20 nm with no intervening basal lamina. A total of 14,694 vesiculated nerve fiber profiles from three control and three extrinsically denervated animals were scored for the presence of immunoreactivity to enkephalin, substance P, vasoactive intestinal peptide, or combinations of these peptides. Analysis of variance showed that the number of profiles labelled for substance P was not different from the number of profiles labelled for vasoactive intestinal peptide and that the number labelled with the substance P and vasoactive intestinal peptide antisera simultaneously were not different from the sum of the numbers obtained with each alone. The number of profiles labelled for substance P plus enkephalin was greater than the number labelled for substance P alone and the number labelled with vasoactive intestinal peptide plus enkephalin was greater than that with vasoactive intestinal peptide alone. Simultaneous labelling for substance P and vasoactive intestinal peptide resulted in immunoreactivity in the same number of profiles as did reaction for all three peptides at the same time. In both cases, about 95% of the profiles were labelled. The results from extrinsically denervated muscle were not different from control circular muscle. These results indicate that nearly all the intrinsic nerve fibers supplying the circular muscle of the guinea pig small intestine contain either substance P or vasoactive intestinal peptide but not both.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗