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Biomedical subjects

M Costa

Publications and source records attributed to M Costa.

At least 505 records · Page 28Linked to original sources
PubMed1982

The induction of DNA strand breakage by nickel compounds in cultured Chinese hamster ovary cells.

Both NiCl2 and crystalline alphaNiS induced DNA strand breaks in cultured Chinese hamster ovary (CHO) cells. Alkaline sucrose gradient analysis of [3H]thymidine radiolabelled DNA isolated from cells exposed to NiCl2 at 1 microgram/ml for only 2 h indicated a high degree of DNA strand breakage. Similarly crystalline alphaNiS caused substantial strand breakage at 1 microgram/ml following a 24-h treatment interval. These nickel compounds caused DNA strand breaks at concentrations which did not significantly impair normal cellular division. A concentration-dependent effect upon the number and average size of DNA fragments was obtained with both NiCl2 and crystalline alphaNiS. Since DNA strand breakage occurred at such low concentrations, these results suggest that nickel compounds which cause cellular transformation have highly selective and specific effects upon DNA structure.

Animals↗
PubMed1982

Somatostatin is contained in and released from cholinergic nerves in the heart of the toad Bufo marinus.

The heart of the toad Bufo marinus contained a substance with somatostatin-like immunoreactivity which eluted with somatostatin on reverse phase high pressure liquid chromatography. Immunoreactivity to somatostatin was localised histochemically to nerve fibers in muscle bundles of the sinus venosus, atria and ventricles and to nerve cell bodies in the sinus venosus and inter-atrial septum. Nerve cell bodies were localised both by interference contrast microscopy and immunohistochemistry; all detectable intracardiac neurons were immunoreactive. Synthetic somatostatin inhibited the rate and force of beat of atrial preparations, but did not affect the driven ventricle. Vagal stimulation caused inhibition of all cardiac chambers. After muscarinic blockade with hyoscine, vagal stimulation with 3 Hz or more still caused inhibition of the pacemaker and atrium, but not of the ventricle. The hyoscine-resistant vagal effects were diminished by about 60% after induction of tachyphylaxis to somatostatin. When when the vagus nerves were stimulated intermittently for 1 h at 10 Hz, in the presence or absence of hyoscine, the effect of somatostatin was reduced by about 60%. It is concluded that the cholinergic postganglionic neurons of the cardiac vagus contain somatostatin. When the vagus is stimulated at 3 Hz or more, the neurons release sufficient somatostatin to inhibit the pacemaker and atrial muscle.

Animals↗
PubMed1982

Neurons with 5-hydroxytryptamine-like immunoreactivity in the enteric nervous system: their projections in the guinea-pig small intestine.

Changes in the distribution of 5-hydroxytryptamine-like immunoreactivity have been examined in enteric neurons at various times after microsurgical lesions of the enteric plexuses. In the myenteric plexus, varicose immunoreactive nerve fibres disappeared or were reduced in number in ganglia anal to an interruption of the myenteric plexus. Up to about 2 mm on the anal side, all varicose immunoreactive fibers disappeared from the ganglia. At about 14-16 mm below an interruption, there were about 50% of the normal number of fibres in the myenteric ganglia and at about 24 mm the innervation was normal. In the submucosa, fibres immunoreactive for 5-hydroxytryptamine were absent from an area on the anal side following interruption of the myenteric plexus. From consideration of the pattern of disappearance, it is deduced that some myenteric nerve cell bodies send immunoreactive axons in an anal direction to supply submucous ganglia. The axons run for about 8 mm in the myenteric plexus, enter the submucosa and then run for a further 4 mm approximately. Thus, varicose fibres immunoreactive for 5-hydroxytryptamine, which occur around the enteric ganglion cells of both plexuses arise from nerve cell bodies in myenteric ganglia than send their axons in an anal direction.

Animals↗
PubMed1982

Neurons with 5-hydroxytryptamine-like immunoreactivity in the enteric nervous system: their visualization and reactions to drug treatment.

Immunoreactive nerve cell bodies and fibres in the intestine have been examined using three antibody preparations raised against 5-hydroxytryptamine. Cross reactivity studies indicate that the substance localized was an hydroxylated indoleamine. In the guinea-pig small intestine, nerve cell bodies were located in the myenteric plexus and varicose fibres were found in the ganglia of the myenteric and submucous plexus. The nerve cell bodies had prominent short, broad processes and a single long process. Similar nerve cells and fibres were found in the guinea-pig stomach and large intestine and areas of intestine that were examined in mice, rabbits and rats. Properties of the neurons were examined in the small intestine of the guinea-pig. The immunoreactive material was depleted by treatment with reserpine, but not by guanethidine or 6-hydroxydopamine in dose sufficient to deplete noradrenaline stores in axons in the intestine. No depletion of 5-hydroxytryptamine by the neurotoxin 5, 7-dihydroxytryptamine was observed. After depletion by reserpine, immunoreactivity of the neurons could be restored by application in vitro of 5-hydroxytryptamine, 5,7-dihydroxytryptamine or 5-hydroxytryptophan. The restoration by 5-hydroxytryptophan was prevented by the inhibitor of L-aminoacid decarboxylase, benserazide. After reserpine treatment, immunoreactivity was not restored by tryptophan. Uptake of 5, 7-dihydroxytryptamine into the nerves was antagonized by fluoxetine. The distribution of neurons with 5-hydroxytryptamine-like immunoreactivity was compared with the distribution of enteric amine-handling neurons that take up and decarboxylate L-dopa. This comparison indicated that there are two classes of aromatic amine neuron in the guinea-pig small intestine, the enteric 5-HT neurons and enteric, non-5-HT, amine handling neurons.

5,7-Dihydroxytryptamine↗
PubMed1982

Substance P-like immunoreactivity in nerves associated with the vascular system of guinea-pigs.

Substance P-like immunoreactivity was localized by an indirect immunohistochemical technique in whole mounts and sections of blood vessels from the guinea-pig. There was a widespread association of nerve fibres that had substance P-like immunoreactivity with blood vessels, extending into all vascular beds. The relative densities of supply of different vessels were assessed visually and a rating scale used to compare them. Large elastic arteries close to the heart had dense networks of immunoreactive nerves associated with them. The density decreased as more peripheral beds were approached, except that there was a particularly dense network of nerves with arteries of the splanchnic beds. Arteries to myocardial, central nervous system, renal, reproductive and skeletal muscle beds all had substance P-immunoreactive nerves associated with them to varying extents. The venae cavae near the heart were densely supplied, but there were few fibres with their more peripheral extensions. Some large veins (e.g. pulmonary, hepatic portal and superior mesenteric) had a few fibres with them, but veins of peripheral vascular beds had very few or no immunoreactive nerve fibres. Substance P-like immunoreactivity in vascular nerves was markedly reduced in guinea-pigs that were injected with capsaicin but was unaffected by the injection of 6-hydroxydopamine. It is concluded that the vascular substance P-immunoreactive nerves are likely to be of sensory origin.

Animals↗
PubMed1982

Extracellular requirements for the endocytosis of carcinogenic crystalline nickel sulfide particles by facultative phagocytes.

Various culture medium components were examined for their effect upon the phagocytosis of carcinogenic crystalline and non-carcinogenic amorphous NiS by cultured fibroblastic cells using both a visual and radioactive assay for phagocytosis. Crystalline NiS was phagocytosed by cells in a simple salts/glucose maintenance medium to an extent similar to that observed in complex culture medium fortified with 10% fetal bovine serum (FBS), suggesting that serum proteins and other components in complex culture medium exert little influence upon the uptake of these heavy metal particles. Phagocytosis of crystalline NiS was shown to be highly dependent upon Ca2+ since omission of Ca2+ from the salts/glucose medium substantially reduced phagocytosis, while readdition of Ca2+ stimulated uptake in a concentration-dependent manner. The uptake of the NiS particles was inhibited by trifluoperazine, a calmodulin antagonist, implicating intracellular Ca2+ in this phagocytosis process. Since the opposite surface charge of crystalline and amorphous NiS has been related to their different phagocytic uptake by cells whose primary function is not phagocytosis (facultative phagocytes), these results show that the culture medium components do not modify the surface charge of these particles in a way that significantly influences their uptake.

Animals↗
PubMed1982

Preparation of 3-mercaptolactic acid and S-aminoethylmercaptolactic acid.

A simple and accurate method is described for synthesis of 3-mercaptolactic acid and its derivative, S-aminoethylmercaptolactic acid. Some spectrometric data of compounds are reported as well as their melting points, some colorimetric reactions and thin layer chromatographic behaviour. S-Aminoethylmercaptolactic acid is also determined by amino acid analyzer.

Amino Acids, Sulfur↗
PubMed1982

Cytoplasmic dissolution of phagocytized crystalline nickel sulfide particles: a prerequisite for nuclear uptake of nickel.

The intracellular fate of particulate crystalline alpha NiS, an inducer of neoplastic transformation which is readily phagocytized by cultured cells, was compared with that of particulate amorphous NiS, which does not have these properties. Amorphous and crystalline NiS both dissolve slowly in complete medium; phagocytized alpha NiS particles remain in the cytoplasm, where they dissolve more rapidly than extracellular particles. Thus the selective phagocytosis of alpha NiS accounts for both high intracellular particle accumulation and high levels of soluble Ni relative to the surrounding medium. Since phagocytized alpha NiS particles do not enter the nucleus, dissolution in the cytoplasm may represent an activation step in carcinogenesis, forming soluble Ni which diffuses into the nucleus. Dissolution products from phagocytized alpha NiS were detected in subcellular fractions isolated from treated cells; the highest levels were found in the nuclei, mitochondria, and lysosomes. That the Ni in the subcellular fractions was dissolved is suggested by the fact that dissolution products from phagocytized alpha NiS were detected in nuclei after centrifugation on sucrose pads, which substantially reduced contamination from cytoplasmic alpha NiS particles. Cytoplasmic dissolution of alpha NiS was enhanced by prior exposure of cells to the same compound. Loss of visible particles from cells was compared with loss of total Ni by use of alpha 63 NiS particles; the particles disappeared from almost half the cells during the first 2 d of treatment, while the total radioactivity associated with the cells and the total number of cells in the monolayer remained the same. The accelerated dissolution of alpha NiS after exposure to the same particles may be due to enhancement of lysosomal enzyme activity by particle phagocytosis. A 20-30% increase in intracellular acid phosphatase activity was observed after treatment with crystalline, but not amorphous, NiS, suggesting enhanced lysosomal activity.

Acid Phosphatase↗
PubMed1982

The phagocytosis and transforming activity of crystalline metal sulfide particles are related to their negative surface charge.

Crystalline nickel sulfide (alpha NiS) and cobalt sulfide (CoS2) particles can cause greater cell transformation and cellular toxicity than the respective amorphous metal sulfide particles. Cultured mammalian cells phagocytose the crystalline metal sulfide particles more readily than the amorphous ones. In the case of the nickel sulfides, the crystalline metal sulfide particles had negatively charged surfaces (Zeta potential: -27.012 mV) in contrast to the amorphous particles, which were positively charge (Zeta potential: +9.174 mV). X-ray photoelectron spectroscopy analysis of amorphous and crystalline NiS particles revealed that the outermost surface (1-4 nm) of the two particles had striking differences in Ni/S ratios and in their sulfur oxidation states. Rendering particles' surfaces more negative by reduction with lithium aluminum hydride enhanced their phagocytosis, and in the case of amorphous NiS chemical reduction resulted in an incidence of morphological transformation of Syrian hamster embryo cells comparable to that observed with untreated crystalline alpha NiS.

Animals↗
PubMed1982

Strand breakage and decreased molecular weight of DNA induced by specific metal compounds.

The effect of various metal compounds on the DNA of Chinese hamster ovary (CHO) cells was studied. Both NiCl2 and crystalline NiS caused DNA strand breaks in cultured CHO cells, whereas amorphous NiS did not. Strand breaks were quantitated by determining the number of average molecular weight of DNA following treatment with the metal compounds. Exposure of cells to crystalline NiS, CoS, CdS, AgS, CuS and Ni3S2 at 10 micrograms/ml for 24 h also induced DNA strand breaks. Similar exposure to activated charcoal, which was also actively phagocytosed, failed to cause any effect on the DNA of CHO cells. In the case of NiCl2 and NiS the effect was shown to be both time and dose dependent. Other soluble metal compounds such as HgCl2, CaCrO4, and CdCl2 also decreased the molecular weight of DNA while MnCl2, ZnCl2 and FeCl2 caused no significantly detectable change in DNA molecular weight. These effects, which occur at low metal concentrations suggest that nickel and other metals which cause cellular transformation have a very selective and specific effect upon DNA.

Animals↗
PubMed1982

Distinctive hair changes (pili torti) in Rapp-Hodgkin ectodermal dysplasia syndrome.

An 8-year-old girl with narrow nose, small mouth, maxillary hypoplasia, cleft palate, hypodontia and hypohidrosis is described. Her scalp hair was coarse, dry and wiry. Microscopic examination showed the hair to be twisted at irregular intervals on its long axis, as seen in pili torti. Her mother has the same features; as a child, she had identical hair and is now bald. Both mother and daughter display signs and symptoms of Rapp-Hodgkin's ectodermal dysplasia. The autosomal dominant inheritance of the disease is further supported by the findings in this family.

Adult↗
PubMed1982

Detection and characterisation of neurotransmitters, particularly peptides, in the gastrointestinal tract.

There are now about twelve substances, many of them peptides, that are thought to act as neurotransmitters in the enteric nervous system. Most of the studies of peptides have relied on immunochemical methods for their detection. However, difficulties arise in these studies because of the close similarities between peptides. Related peptides can be grouped in several ways according to similarities of origin, function, effects in bioassays and amino acid sequences. Peptides with the same function in different species, and only slight differences in amino acid sequence, have been called isopeptides. Peptide families that have sequences of amino acids in common, but do not necessarily have similar functions are described. In the guinea-pig small intestine, used as a model, the concentrations of fourteen nerve-related peptides and amines are compared. The actual chemical natures of the peptides are discussed. It is concluded that nerves containing authentic leu- and met-enkephelin, somatostatin and substance P are present. VIP in guinea-pig enteric nerves is different from the porcine standard. Peptides similar to authentic CCK8 and amphibian skin bombesin are present. Angiotensin and neurotensin-like peptides shown immunohistochemically are not the authentic peptides. In the longitudinal muscle plus myenteric plexus, most neuropeptide concentrations are in the range of 10-500 pmole/g. The exception is met-enkephalin (1,300 pmole/g). The amine transmitters have considerably higher concentrations, noradrenaline having a concentration of about 3,500 pmole/g and acetylcholine 1-2 x 10(5) pmole/g.

Angiotensins↗
PubMed1982

Video time-lapse microscopy of phagocytosis and intracellular fate of crystalline nickel sulfide particles in cultured mammalian cells.

The endocytosis and intracellular distribution of carcinogenic crystalline nickel sulfide (NiS) particles in Chinese hamster ovary cells were studied using time-lapse video recording with phase-contrast and bright-field optics. Crystalline NiS particles were phagocytosedd by Chinese hamster ovary cells in regions of membrane ruffling. While these particles may remain bound to the cell surface for variable time intervals (min to hr), their internalization generally required only 7 to 10 min. Endocytosed crystalline NiS particles exhibited saltatory motion, and lysosomes were observed to interact repeatedly with the particles in a manner similar to that observed during the digestion of macropinosomes. Particles were never observed to be exocytosed from the cell, and with time, most of the internalized particles aggregated in the region around the nucleus. After 24 to 48 hr, particle saltation decreased to a point where the particle position became relatively fixed in the perinuclear region, and in some instances, this was associated with a conspicuous vacuole formation around the particles. It is concluded that the uptake and distribution of crystalline NiS particles occur by normal endocytic and saltatory processes as occur during the formation and breakdown of macropinosomes. The observed lysosomal interaction with phagocytoses cytoplasmic NiS may accelerate particulate nickel dissolution allowing entry of ionic nickel into the nucleus.

Animals↗
PubMed1982

Selective phagocytosis of crystalline metal sulfide particles and DNA strand breaks as a mechanism for the induction of cellular transformation.

Crystalline NiS, CuS, CoS2, and CdS particles were actively phagocytosed by cells and potently induced morphological transformation of Syrian hamster embryo cells in a concentration-dependent fashion. In contrast, the respective amorphous metal sulfide particles (amorphous NiS, CuS, CoS, and CdS) were not as actively phagocytosed by cultured cells and, in comparison to the crystalline form of these compounds, induced considerably less morphological transformation at both cytotoxic and noncytotoxic exposure levels. Chemical reduction of positively charged amorphous NiS with LiAlH4 resulted in active phagocytosis of these particles which was also associated with enhancement of cellular transformation. Crystalline but not amorphous NiS caused considerable strand breaks in the DNA of Chinese hamster ovary cells following 2 to 3 hr exposure at 10 micrograms/ml as determined by alkaline sucrose gradient techniques with subsequent determination of DNA molecular weight. Phagocytized inert particles such as latex beads did not induce transformation or DNA damage, suggesting that genotoxic dissolution products such as Ni2+ rather than the phagocytized particles are responsible for the observed DNA damage and cellular transformation. NiCl2 was about one-third to one-half as potent in inducing cellular transformation compared to crystalline NiS on a weight basis. These results correlate the selective phagocytosis of crystalline metal sulfides to their more potent activity in the induction of cellular transformation.

Animals↗
PubMed1982

Toxic metals produce an S-phase-specific cell cycle block.

In order of decreasing potency, CdCl2 greater than HgCl2 greater than CoCl2 greater than CuSO4 greater than NiCl2 greater than ZnCl2 and PbSO4 slowed cell growth at concentrations ranging from 1 microM to 60 microM. Flow cytometry analysis of cell cycle position indicated that cell growth was selectively blocked in S phase by these concentrations. Water insoluble metals such as As, Ni, crystalline Ni3S2, crystalline NiS, crystalline Ni3Se2 and NiO also resulted in an S phase blockage of cells at concentrations of 1 to 10 micrograms/ml. The crystalline nickel sulfide and selenide compounds as well as As metal were the most potent of these. At higher concentrations blockage of cells in mitosis was also evident with a number of the water insoluble metal compounds. The potency of the metal compounds in blocking cells in S phase was related to their chemical reactivity and their uptake into cells. The S phase specific blockage produced by the metals examined was consistent with their genotoxic or carcinogenic activity since such activity indicated a selective interaction with DNA metabolism.

Animals↗
PubMed1981

Depletion by capsaicin of substance P-immunoreactivity and acetylcholinesterase activity from nerve fibres in the guinea-pig heart.

The sensitivity to capsaicin of substance P-immunoreactive nerve fibres in the hearts of guinea-pigs was examined. Capsaicin decreased considerably the substance P-immunoreactive material in nerve fibres of the parietal pericardium, atria, bicuspid and tricuspid valves. Pericardial and valvar nerve fibres localized by acetylcholinesterase (AChE) histochemistry had a distribution and density pattern similar to that of the substance P immunoreactive fibres. Capsaicin treatment also decreased the number of visible AChE-positive nerve fibres. It is known that capsaicin has a selective action on those substance P-immunoreactive fibres that are of sensory origin; thus, these results imply that substance P-immunoreactive fibres in the heart are sensory. Moreover, the results suggest that some of the nerve fibres localized in the heart by AChE histochemistry are substance P-containing sensory fibres.

Acetylcholinesterase↗