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Biomedical subjects

M Costa

Publications and source records attributed to M Costa.

At least 433 records · Page 24Linked to original sources
PubMed1986

Characterization of DNA lesions induced by CaCrO4 in synchronous and asynchronous cultured mammalian cells.

Alkaline elution studies demonstrated CaCrO4-induced DNA single strand breaks and DNA-protein crosslinks. DNA single strand breaks increased following treatment with 10-400 microM CaCrO4 in Chinese hamster ovary cells maintained with a minimal salts/glucose medium. DNA single strand breaks were rapidly repaired when extracellular CaCrO4 was removed even following exposure levels of CaCrO4 (200 microM for 2 hr) which reduced survival to 0.6%. Under these exposure conditions the trypan blue exclusion was greater than 80%, whereas cell growth was inhibited by 46% within 24 hr. The DNA-protein crosslinks induced by 10 microM CaCrO4 were repaired in the absence of metal within 24 hr. In contrast, the amount of DNA-protein crosslinks measured 24 hr after a 2-hr treatment with 50, 100, and 200 microM CaCrO4 remained unchanged at the 50 microM level or increased at the two higher concentrations. Thus, at concentrations of 50 microM or greater there was no repair of the DNA protein crosslinks, and this may have been due to cytotoxicity of the metal. CaCrO4 at 10 or 25 microM exposure for 6 hr also induced DNA-protein crosslinking in Chinese hamster ovary cells maintained in normal tissue culture growth media. The lack of repair of DNA-protein crosslinks at the 25 microM level, which did not substantially reduce cell survival, indicated the persistence of these lesions in a noncytotoxic form. Uptake of CaCrO4 was linear with all of the concentrations tested. Analysis of the cell cycle sensitivity to CaCrO4 revealed that cells in early S phase were the most sensitive to the cytotoxic and strand breaking activity of CaCrO4. Compared with other phases of the cell cycle, there was also an elevated level of DNA-protein crosslinks when cells were treated in early S phase and incubated 24 hr without CaCrO4. These results implicate the DNA-protein crosslink as an important lesion that may be responsible for the cytotoxic and carcinogenic properties of chromate.

Animals↗
PubMed1986

Comparison of DNA lesions and cytotoxicity induced by calcium chromate in human, mouse, and hamster cell lines.

DNA lesions, cytotoxicity, and cellular uptake of CaCrO4 were compared in Chinese hamster ovary, in mouse embryo fibroblast C3H10T1/2, and in human osteosarcoma cells. The concentration of CaCrO4 that reduced colony formation by 50% was 2- or 3-fold less in human osteosarcoma cells than in C3H10T1/2 or Chinese hamster ovary cells. Alkaline elution studies showed that CaCrO4 induced DNA single strand breaks in a concentration dependent manner in all three cell lines. However, the human cells exhibited four times more breaks than the hamster cells and two times more than C3H10T1/2 cells when the CaCrO4 exposure conditions were equivalent. Alkaline elution studies also demonstrated the formation of DNA-protein cross-links by CaCrO4 in all three cell lines. In hamster and mouse cells the induction of these DNA-protein cross-links was dependent on concentrations that ranged from 5 to 50 microM for 6 h; however, the cross-links were saturated at 25 microM in human cells and at 50 microM in mouse and hamster cells. The level of cross-links was four times greater in the human cells compared to the mouse cells and was a factor of 2 greater in the hamster cells compared to the mouse cells. The uptake of CaCrO4 was linear with respect to time and concentration. Uptake of CaCrO4 was equivalent in the human and mouse cells, but was a factor of 4 less in the hamster cells. The single strand breaks were almost entirely repaired after an 18-h incubation in metal free medium in all three cell lines, whereas DNA-protein cross-links persisted in these cell lines in proportion to their initial levels. These results demonstrate differences in the sensitivity of human, hamster, and mouse cells to CaCrO4 and suggest that the repair-resistant DNA-protein cross-link may be important in mediating the long term toxic and carcinogenic effects of CaCrO4.

Animals↗
PubMed1986

Differences in the effects of Hg(II) on DNA repair induced in Chinese hamster ovary cells by ultraviolet or X-rays.

The effect of relatively nontoxic levels of HgCl2 on semiconservative DNA synthesis and on DNA repair induced following treatment of intact cells with X-ray or ultraviolet (UV) light has been studied in cultured Chinese hamster ovary cells. In the presence of 1 microM HgCl2 the repair of DNA strand breaks induced by 450 rads of X-rays was reduced by 37%. If a treatment of 2.5 microM HgCl2 was given to cells for only 15 min prior to a 450-rad irradiation, the rate of repair was reduced even further with only 25% of the breaks being repaired in the first hour following irradiation. When comparable treatments of HgCl2 were given to Chinese hamster ovary cells in conjunction with UV irradiation there was no significant effect on either the number of initial strand scission events or the return to high molecular weight DNA following completion of repair. Only after exposure of cells to toxic levels of Hg(II) (higher concentrations or longer treatments) was there measurable inhibition of UV-induced repair as evidenced by a reduced rate of ligation of DNA to a high molecular weight form. Inhibition of the endonuclease step of UV repair was not observed since Hg(II)-treated cells exhibited the same level of strand scission immediately following UV as cells not treated with Hg(II). The observed differences in the effects of Hg(II) on two pathways for DNA repair indicate that the potential for synergistic action between Hg(II) and other DNA damaging agents will be determined in part by the repair pathways induced by each agent. Additionally, it was found that inhibition of semiconservative synthesis also occurs at low concentrations of HgCl2 similar to those affecting X-ray-induced repair. The presence of Hg-DNA adducts in the DNA at these concentrations may cause a reduction in normal replication to facilitate DNA repair.

Animals↗
PubMed1985

Co-localization of neuropeptide Y, vasoactive intestinal polypeptide and dynorphin in non-noradrenergic axons of the guinea pig uterine artery.

Two major populations of perivascular axons containing immunoreactivity to neuropeptide Y (NPY) have been revealed in the main uterine artery of the guinea pig by immunohistochemical procedures which allow the simultaneous visualization of two antigens. One population contained immunoreactivity to dopamine-beta-hydroxylase (D beta H) and was presumably noradrenergic. The other main population of axons with NPY-like immunoreactivity (NPY-LI) did not have D beta H-like immunoreactivity (D beta H-LI) and was presumably non-noradrenergic. These non-noradrenergic axons also contained immunoreactivity to vasoactive intestinal polypeptide (VIP) and dynorphin (DYN). Indeed, nearly all axons with VIP-LI also contained NPY-LI and DYN-like immunoreactivity (DYN-LI). NPY constricted the uterine artery perfused in vitro, whilst VIP dilated uterine arteries preconstricted with noradrenaline or NPY. Thus, we have evidence for the coexistence of a vasoconstrictor peptide and a vasodilator peptide in the same non-noradrenergic perivascular axons, which also contain an opioid peptide, dynorphin.

Animals↗
PubMed1985

Peptide neurons in the canine small intestine.

The distributions of peptide-containing nerve fibers and cell bodies in the canine small intestine were determined with antibodies raised against seven peptides: enkephalin, gastrin-releasing peptide (GRP), neuropeptide Y, neurotensin, somatostatin, substance P, and vasoactive intestinal peptide (VIP). Immunoreactive nerve cell bodies and fibers were found for each peptide except neurotensin. In the muscle layers there were numerous substance P, VIP, and enkephalin fibers, fewer neuropeptide Y fibers, and very few GRP or somatostatin fibers. The mucosa contained many VIP and substance P fibers, moderate numbers of neuropeptide Y, somatostatin, and GRP fibers and rare enkephalin fibers. Nerve cell bodies reactive for each of the six neural peptides were located in both the myenteric and submucous plexuses. The distributions of nerve cell bodies and processes in the canine small intestine show many similarities with other mammals, for example, in the distributions of VIP, substance P, neuropeptide Y, and somatostatin nerves. There are some major differences, such as the presence in dogs of numerous submucosal nerve cell bodies with enkephalinlike immunoreactivity and of GRP-like immunoreactivity in submucous nerve cell bodies and mucosal fibers.

Animals↗
PubMed1985

Distribution of certain peptide-containing nerve fibres and endocrine cells in the gastrointestinal mucosa in five mammalian species.

The distribution of mucosal nerve fibres containing vasoactive intestinal peptide (VIP), substance P, somatostatin, neuropeptide Y (NPY), and enkephalinlike immunoreactivity was mapped by conventional immunohistochemical techniques throughout the mucosa of the esophagus, stomach, small and large intestines, and gall bladder. In addition, the distributions of endocrine cells immunoreactive for three peptides localized by these antisera (namely somatostatin, pancreatic polypeptide, and substance P) were recorded. Tissues from guinea pigs, rats, dogs, marmosets, and humans were studied. It was hoped that this information would enable possible target tissues and functional roles for the peptides to be identified. In the mucosa, peptide nerve fibres were found throughout the lamina propria, including some which were close to the epithelium and others associated with small blood vessels. Although there was a general similarity of peptide nerve distribution between regions and species, many small variations were observed. VIP and substance P fibres were the most prevalent nerve type; NPY fibres were also usually quite common. The distribution of somatostatin fibres was extremely variable between regions and species, and enkephalin fibres were usually rare. Endocrine cells of open (flask- or pyramid-shaped) and closed (rounded) types were seen; basal cytoplasmic processes (of variable length) were seen on many cells immunoreactive for somatostatin or pancreatic polypeptide. Epithelial cells immunoreactive for substance P were seen in the dog, marmoset, and human. The distributions and shapes of endocrine cells varied widely between areas and species. These studies provide a basis for the correlation of nerve distribution with pharmacological and physiological studies.

Animals↗
PubMed1985

Co-localization of calcitonin gene-related peptide-like immunoreactivity with substance P in cutaneous, vascular and visceral sensory neurons of guinea pigs.

Calcitonin gene-related peptide (CGRP) has been immunohistochemically co-localized with substance P (SP) in capsaicin-sensitive, varicose axons supplying the skin, viscera and cardiovascular system of the guinea pig. After treatment with colchicine in vitro, 82% of SP neurons in the dorsal root ganglia contained CGRP-like immunoreactivity while 96% of CGRP neurons were immunoreactive for SP. Both CGRP- and SP-like immunoreactive material are transported peripherally and centrally from dorsal root ganglia. Thus, in tissues such as the gut where there are intrinsic nerves containing SP but lacking CGRP, CGRP-like immunoreactivity is a useful means of specifically labelling axons of most sensory neurons containing SP.

Animals↗
PubMed1985

Determination of 3-mercaptolactic acid by amino acid analyzer after aminoethylation.

A quantitative determination of 3-mercaptolactic acid was performed after its conversion into S-aminoethylmercaptolactic acid by reacting with excess of 2-bromoethylamine. S-aminoethylmercaptolactic acid was quantitated by an amino acid analyzer. Other thiols were shown not to interfere with the determination of 3-mercaptolactic acid. The sensitivity of the method was at the nanomoles level. The application of the method to the determination of 3-mercaptolactic acid in human urine is also reported.

Amino Acids, Sulfur↗
PubMed1985

Management of retroperitoneal haematoma following penetrating trauma.

Experience with the management of 106 consecutive patients found to have a retroperitoneal haematoma (RH) at laparotomy for penetrating trauma over a 2-year period is reviewed. Three types of retroperitoneal haematoma are recognized: Type I (central), Type II (flank) and Type III (pelvic). Type I RH was present in 22 patients as a result of injuries to the inferior vena cava (9), the aorta (5), the pancreas and duodenum (5), the portal vein (2), and to both aorta and inferior vena cava (1). Fourteen patients died (63.8 per cent) representing 70 per cent of all deaths in the series. Type II RH was seen in 73 patients. Thirty-two were stable and the perinephric fascia was not opened with no morbidity or mortality. Forty-one were explored: 15 on pre-operative evidence of renal injury which was confirmed at laparotomy. In the remaining 26 a stable haematoma was explored and no significant lesion found. It is considered that in 45 of 73 Type II RH (61.0 per cent) exploration was unnecessary. Five patients died (6.8 per cent). Type III RH was found in 11 patients and was due to iliac vessel injuries. Two patients died. In conclusion Type I and III RH should be routinely explored. Stable Type II RH discovered at laparotomy should be explored selectively based on pre-operative clinical and radiological assessment of renal injury.

Abdominal Injuries↗
PubMed1985

Neurochemically similar myenteric and submucous neurons directly traced to the mucosa of the small intestine.

Antisera to neuropeptide Y (NPY) gave an intense immunohistochemical reaction of certain nerve cells in the myenteric and submucous plexuses of the guinea-pig small intestine. Each nerve cell had up to 20 branching, tapering processes that were less than approximately 50 micron long and a long process that could be followed for a considerable distance. This morphology corresponds to that of the type-III cells of Dogiel. The long process of each myenteric cell ran through the circular muscle to the submucosa, and in most cases the process could be traced to the mucosa. The submucous nerve cell bodies also had processes that extended to the mucosa. These cell bodies, in both plexuses, also stained with antisera raised against calcitonin gene-related peptide (CGRP), cholecystokinin (CCK), choline acetyltransferase (ChAT) and somatostatin (SOM), but did not stain with antibodies against enkephalin, substance P or vasoactive intestinal peptide. Thus, it has been possible for the first time to trace the processes of chemically specified neurons through the layers of the intestinal wall and to show by a direct method that CGRP/CCK/ChAT/NPY/SOM myenteric and submucous nerves cells provide terminals in the mucosa.

Animals↗
PubMed1985

Different substance P receptors are found on mucosal epithelial cells and submucous neurons of the guinea-pig small intestine.

The action of substance P (SP) on mucosal ion transport has been investigated in the guinea-pig small intestine. Segments of intestine were dissected free of external muscle and myenteric plexus and mounted in Ussing chambers. Short-circuit current (Isc) was measured as an indication of net ion transport across the tissue. SP (greater than 10(-10) M) added to the submucosal side of the tissue caused a transient increase in Isc. Tetrodotoxin (TTX, 10(-7) M) decreased the maximum SP response to 11% of the control value. TTX completely inhibited the response to electrical field stimulation but had no effect on Isc increases due to carbachol or theophylline. In the presence of hyoscine (10(-7) M) the SP response was reduced to 42% of the control value, but hyoscine had no effect on the TTX-resistant SP response. Mepyramine (10(-6)M) had no significant effect on the SP response. These results suggest that SP alters mucosal ion transport by stimulation of cholinergic and non-cholinergic nerves in the mucosa-submucosa. A small part of the SP response appears to be due to a direct action on epithelial cells. The SP antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11)-SP decreased the magnitude of the TTX-resistant SP response, and caused a decrease of similar magnitude in the total SP response. These results imply that the major component of the SP response, which is due to an action on neurons, is unaffected by this antagonist. It is concluded that the SP receptors on epithelial cells are blocked by the antagonist and are different to the SP receptors on submucous neurons, which are not blocked by the antagonist.

Animals↗
PubMed1985

Investigations of nerve populations influencing ion transport that can be stimulated electrically, by serotonin and by a nicotinic agonist.

It is known that the majority of the mucosal nerve fibres in the guinea-pig small intestine arise from submucous ganglia. There are a number of neurochemically distinct populations of nerve cells in these ganglia, approximately half of them being cholinergic. In these studies we have stimulated isolated preparations of mucosa and submucosa with electrical field stimulation (EFS), 5-hydroxytryptamine (5-HT) and the nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium (DMPP) and monitored changes in ion transport. Segments of intestine were dissected free of external muscle and myenteric plexus and mounted in Ussing chambers. Short-circuit current (Isc) was measured as an indication of net ion transport across the tissue. EFS consisted of passing bipolar rectangular stimulus pulses through two platinum wires, one placed on each of the mucosal and submucosal sides of the tissue. EFS, 5-HT and DMPP each caused a transient increase in Isc. Tetrodotoxin (TTX) abolished all of the EFS response and the majority of the response observed with 5-HT or DMPP, suggesting that the action of these stimuli on the mucosa is primarily nerve-mediated. The TTX-sensitive responses to 5-HT (greater than 5 X 10(-7) M) and DMPP consisted of two components, appearing with different latencies. The response to EFS also consisted of two components. Hyoscine abolished the first component of each of these responses and significantly reduced the amplitude of the second, by 40% (for EFS and 5-HT) and 84% (for DMPP). At lower 5-HT concentrations, only the later component was seen, and this was unaffected by hyoscine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Substance P enteric neurons mediate non-cholinergic transmission to the circular muscle of the guinea-pig intestine.

The sites of action and possible roles of substance P in contracting the circular muscle of the guinea-pig ileum were studied using two analogues of substance P that act as antagonists of some of its actions. These are D-Arg1, D-Pro2, D-Trp7,9, Leu11-substance P and D-Pro2, D-Trp7,9-substance P, referred to by the single letter amino acid codes for the substituting amino acids as (RPWWL)-SP and (PWW)-SP, respectively. Records of circular muscle activity were taken from strips of intestine free of mucosa and submucosa and from rings with all layers of intestine intact. Substance P was equally effective in contracting the circular muscle strips as it was in contracting the longitudinal muscle. The contractions of strips were not blocked by hyoscine (2 X 10(-6) M) or tetrodotoxin (6 X 10(-7) M), but were substantially reduced by (RPWWL)-SP (6.7 X 10(-6) M) or (PWW)-SP (2 X 10(-5) M). In contrast, contractions of the circular muscle of whole rings of intestine elicited by low concentrations of substance P (4 X 10(-7) M) were blocked by hyoscine or tetrodotoxin but not reduced by the substance P antagonists in the concentrations referred to above. These observations indicate that the antagonists are effective at receptors for substance P on the muscle, but not at substance P receptors on enteric cholinergic nerves. Transmural stimulation of strips of circular muscle or of intestinal rings in the presence of hyoscine evoked contractions that were blocked by tetrodotoxin. These hyoscine-resistant, nerve-mediated contractions could be elicited by single pulses in the strips.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Separate populations of opioid containing neurons in the guinea-pig intestine.

Double staining immunofluorescence techniques were applied to investigate the co-existence of enkephalin, dynorphin and vasoactive intestinal peptide immunoreactivity in the guinea-pig enteric nervous system. Segments of guinea-pig small intestine were incubated for 24h in a culture medium with colchicine. Several subpopulations with overlapping immunoreactivities were found, i.e. neurons with enkephalin and vasoactive intestinal peptide, with enkephalin and dynorphin and with all three neuropeptides. It is probable that subpopulations with dynorphin and vasoactive intestinal peptide and with each neuropeptide only are also present. These subpopulations of enteric neurons with multiple neurochemical subcoding are likely to have different connections and functions.

Animals↗
PubMed1985

DNA-protein cross-links induced by nickel compounds in intact cultured mammalian cells.

The carcinogenic activity of crystalline NiS has been attributed to phagocytosis and intracellular dissolution of the particles to yield Ni2+ which is thought to enter the nucleus and damage DNA. In this study the extent and type of DNA damage in Chinese hamster ovary CHO cells treated with various nickel compounds was assessed by alkaline elution. Both insoluble (crystalline NiS) and soluble (NiCl2) nickel compounds induced single strand breaks and DNA protein cross-links. The single strand breaks were repaired relatively quickly but the DNA-protein cross-links were present and still accumulating 24 h after exposure to nickel. Single strand breakage occurred at both non-cytotoxic and cytotoxic concentrations of nickel, however, DNA-protein cross-linking was absent when cells were exposed to toxic nickel levels. The concentration of nickel that induced DNA-protein cross-linking correlated with those metal concentrations that reversibly inhibited cellular replication.

Animals↗
PubMed1985

Immunological monitoring of plasma exchange in primary IgA nephropathy.

Plasma exchange (PE) has recently been proposed for primary immunoglobulin (Ig)-A nephropathy (PIgAGN) with progressive course. To develop suitable guidelines for PE in these cases, the authors evaluated the clinical usefulness of some immunological parameters in five patients with PIgAGN treated with PE combined with immunosuppressive drugs and small doses of corticosteroids. These parameters included the levels of IgA-containing immune complexes (IgAIC) by a specific conglutinin assay, the function of the mononuclear phagocyte system (MPS) by the in vivo clearance of IgG-sensitized erythrocytes, and complement activation as determined by C3d measurement. HLA types were also determined. Three patients had an acute nephritic syndrome with a rapidly progressive course, one of them showing sclerotic histologic changes. The two other cases had a relentless progression toward renal failure. In the patient with sclerotic PIgAGN, the MPS function was normal and the IgAIC and C3d levels were low throughout the treatment. In the other four cases, the high IgAIC and C3d levels and the MPS dysfunction found before treatment markedly improved after several PEs. The immunological parameters remained normal during the post-PE follow-up in two cases with acute nephritic syndrome and rapidly progressive course, but worsened again in two cases with a relentless course, particularly in one who possessed the B8/DR3 HLA type. Immunological monitoring including IgAIC, C3d, and MPS function is proposed, in addition to histological and clinical evaluation, as a guideline for PE in PIgAGN with evolving course.

Adolescent↗
PubMed1985

Gastrointestinal myoelectric activity in conscious guinea pigs.

Myoelectric activity was recorded from the gastric antrum and small intestine of conscious, unrestrained guinea pigs using bipolar Ag-Ag chloride electrodes that had been previously implanted under pentobarbital sodium/Innovar anesthesia. In fasted guinea pigs, the migrating myoelectric complex (MMC) was recorded from the small intestine and was observed to propagate aborally at a speed that declined with distance from the pylorus (range of speeds of the front of phase 3: 17.5 cm/min in the duodenum to 4.1 cm/min in the ileum). The complex was not disrupted by feeding but occurred less frequently in the freely fed state (82-min cycle period in the fasted state versus 139 min in the fed state). The complex started in the duodenum and was accompanied by a brief (6.3 +/- 0.9 min) period of inhibition of antral myoelectric activity. Slow waves were also recorded from the gastric antrum (10.3 +/- 1.3/min) and the small intestine. The frequency of intestinal slow waves was uniform along the length of the bowel (26.2 +/- 1.3/min in the duodenum to 24.7 +/- 1.3/min in the ileum). It is concluded that the guinea pig is similar to other mammalian species, so far examined, in its pattern of gastrointestinal myoelectric activity.

Action Potentials↗