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Biomedical subjects

C López

Publications and source records attributed to C López.

At least 145 records · Page 8Linked to original sources
PubMed1986

The molecular organization of the protein HC-IgA complex (HC-IgA).

Complexes of protein HC and monoclonal IgA1 or IgA2 or polyclonal IgA were isolated from human blood plasma. Dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting showed that all complexes contain three types of chains: two light immunoglobulin chains, one regular IgA alpha-chain, and one chain with Mr = 90,000 carrying both alpha-chain and protein HC epitopes. The complexes were split into Fab alpha and Fc alpha fragments by bacterial IgA proteases. The protein HC epitopes were linked to the Fc fragments. Complexes of protein HC and an alpha-chain devoid of the variable region and the first heavy chain constant domain could also be demonstrated to be present in the blood plasma of a patient with alpha-heavy chain disease. Pepsin digestion of HC-IgA released a fragment containing all the protein HC epitopes and the C-terminal nonapeptide of the IgA alpha-chain. The light immunoglobulin chains, the regular alpha-chain, and the 90,000-Da chain from monoclonal HC-IgA1 were isolated by preparative dodecyl sulfate-polyacrylamide gel electrophoresis and by repeated gel filtration in dodecyl sulfate-containing buffer. The N-terminal amino acid sequence of the alpha-chain was identical with that of a regular human heavy immunoglobulin chain of subgroup III. Subtractive degradations of the 90,000-Da chain displayed 2 amino acid residues in each position in a pattern suggesting simultaneous degradations of a chain identical with the regular alpha-chain of HC-IgA and of uncomplexed, low molecular weight, protein HC. All the results are compatible with a model for HC-IgA in which a single low molecular weight protein HC polypeptide chain is covalently linked, side by side, to the C-terminal nonapeptide of one of the two alpha-chains of a regular monomeric IgA unit.

Alpha-Globulins↗
PubMed1986

Regional effect of organochlorine insecticides on cholinergic muscarinic receptors of rat brain.

In different brain regions of the rat we studied the effect of chronic feeding with the organochlorine insecticides p,p'-DDT and gamma-HCH on the cholinergic muscarinic receptors. Using [3H]quinuclidinyl benzylate binding to membranes from cerebral cortex, medulla pons, diencephalon, and cerebellum it was found that the two insecticides produced a decrease in the number of muscarinic receptor sites in cerebellum; while gamma-HCH also reduced these receptors in diencephalon. In both cases no changes in receptor affinity were observed. It is suggested that the chronic treatment with these organochlorine insecticides may cause an alteration in cholinergic transmission leading to a down regulation of the muscarinic receptor in certain brain regions.

Animals↗
PubMed1986

Mutagenicity study on pyrazole, seven pyrazole derivatives, and two nitroimidazoles with the L-arabinose resistance test of Salmonella typhimurium.

The mutagenicity of pyrazole and seven pyrazole derivatives (4-nitropyrazole, 4-bromopyrazole, 1-methyl-4-nitropyrazole, 3,5-dimethyl-4-nitropyrazole, 1-methyl-4-bromopyrazole, 4,4'-dinitro-1, 1'-methylene-dipyrazole and 4,4'-dibromo-1,1'-methylene-dipyrazole) has been investigated with the L-arabinose forward mutation assay of Salmonella typhimurium. Two nitroimidazoles (1-methyl-5-nitroimidazole and metronidazole) were included as reference drugs. The mutagenicity of each chemical was determined by both preincubation and liquid tests, in the presence or absence of S9 microsomal fraction. The mutagenic response was expressed as the absolute number of L-arabinose resistant mutants growing in selective plates, supplemented with traces of D-glucose. Strain BA13 with a wildtype lipopolysaccharide barrier was used as a comparison to the deep rough derivative BA9. No mutagenic effect was detected with pyrazole and two of its derivatives, 1-methyl-4-bromopyrazole and 4,4'-dibromo-1,1'-methylene-dipyrazole. The other five pyrazole derivatives were mutagenic to different degrees, although their mutagenic potencies were always considerably lower than those of the two nitroimidazoles. The results suggest that 4-nitropyrazoles, as well as 4,4'-dinitro-1, 1'-methylene-dipyrazoles, should be investigated further as alternatives to, or even substitutes for, the currently used nitroimidazoles.

Antitrichomonal Agents↗
PubMed1985

Toxic-oil syndrome. Gallium-67 scanning and bronchoalveolar lavage studies in patients with abnormal lung function.

The toxic-oil syndrome (TOS) is a multisystem disorder whose etiology and pathogenesis are as yet unknown. Lung alterations persist in a significant number of TOS patients due to the underlying vascular lesion. Computer-assisted 67Ga scanning and bronchoalveolar lavage (BAL) studies were performed in 14 TOS patients with sustained abnormal diffusing capacity for carbon monoxide (Dco). No significant difference was observed between the 67Ga uptake index of the TOS and control populations. Likewise, there was no significant difference in the number of effector cells recovered from the lungs of TOS patients and controls by bronchoalveolar lavage. However, a rise in IgA and IgG concentrations (p less than 0.002) and a fall in alpha 1-antitrypsin (p less than 0.05) and transferrin (p less than 0.01) were observed in the TOS group. Phospholipid and lecithin concentrations in the lavage fluid were similar for patients and controls. The alveolar macrophage function assayed in three TOS patients was normal. These observations raise new questions about the outcome of lung pathology in TOS and warrant further follow-up studies of the lung abnormalities observed.

Adolescent↗
PubMed1985

[Effect of the method of blood extraction on plasma levels of renin in the Wistar rat].

To investigate the influence of blood extraction conditions on the renin-angiotensin system in rats, plasma renin activity (PRA) and plasma renin concentration (PRC) were measured in blood samples obtained by different methods. PRA and PRC in samples obtained by chronic catheterization, cardiac puncture without anesthesia, and decapitation immediately following light ether anesthesia were not significantly different from those obtained by simple decapitation (control group). In contrast, PRA and PRC in samples obtained by cardiac puncture and cavernous sinus puncture after light ether anesthesia were significantly (p less than 0.01) higher than those obtained in the control group. There was a significant direct correlationship between PRA and PRC in all samples studied (r = 0.87, p less than 0.001). The present results suggest that light ether anesthesia increases renin levels, except when blood samples are taken by decapitation, and that chronic catheterization and cardiac puncture are the choice blood extraction methods to evaluate the renin-angiotensin system in rats.

Anesthesia, General↗
PubMed1983

Isolation of human complex-forming glycoprotein, heterogeneous in charge (protein HC), and its IgA complex from plasma. Physiochemical and immunochemical properties, normal plasma concentration.

Human complex-forming glycoprotein, heterogeneous in charge (protein HC) has previously been isolated from urine and immunochemically shown to be present in low and high molecular weight forms in blood plasma (Tejler, L., and Grubb, A. O. (1976) Biochim. Biophys. Acta 439, 82-94). In the present work, the major low and high molecular weight forms of the protein were isolated from plasma by immunosorption followed by gel chromatography. The plasma low molecular weight protein HC and the urinary protein had similar, if not identical, molecular weight, amino acid composition, NH2-terminal and carboxyl-terminal amino acid sequences and electrophoretic mobility. The low molecular weight plasma protein HC carried a yellow chromophore like the urinary protein, but its molar extinction coefficient at 280 nm was lower and its charge heterogeneity less pronounced than that of urinary protein HC. The plasma high molecular weight protein HC had a hydrodynamic volume which was greater than that of monomeric IgA but smaller than that of dimeric IgA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the isolated high molecular weight protein followed by electrophoretic blotting and immunochemical analysis demonstrated that the protein contained four polypeptide chains: two light immunoglobulin chains (Mr = 23,000), one IgA alpha-chain (Mr = 54,000), and one chain with Mr approximately 90,000 which carried both alpha-chain and protein HC antigenic determinants. Whether the protein HC X IgA complex is a functionally significant part of the humoral immune system cannot be decided without further experimentation, but the complex was found to be completely absent from the blood plasma of patients with a selective deficiency of IgA-secreting immunocytes. The isolated low and high molecular weight plasma protein HC components were used as standard proteins in the construction of a quantitative crossed immunoelectrophoretic assay for the simultaneous quantitation of the two major protein HC components in blood plasma. The plasma concentrations of the low and high molecular weight protein HC components were measured by this method in 13 healthy Caucasians. The results for the low molecular weight protein HC were: mean, 20.3 mg/liter, S.D., 3.2 mg/liter, range, 13.6-26.0 mg/liter; and for the protein HC X IgA complex: mean, 293 mg/liter, S.D., 176 mg/liter, range, 36-620 mg/liter.

Adult↗
PubMed1983

A probable monogenic form of polyostotic fibrous dysplasia.

A 37 year-old female patient with polyostotic fibrous dysplasia (PFD) is described. She presented the typical "café au lait" spots and severe bone involvement including a maxillary osteosarcoma. The father, four sibs, two nephews, two paternal aunts and two paternal first cousins were clinically examined, and seven of them also radiologically evaluated. "Café au lait" spots were found in the father, three sibs, one nephew, one aunt and one first cousin. Although no definite PFD bone lesions, mild radiological abnormalities were found in the father, three sibs and one nephew. These findings were interpreted as the variable expression of a pleiotropic gene. The present observation and three previous familial cases of this entity strongly suggest the existence of a form of PFD determined by an autosomal dominant gene.

Adolescent↗
PubMed1981

Photometric measurement of lipoprotein-cholesterol after agarose electrophoresis: comparison with single-spin ultracentrifugal analysis.

A method is presented for the evaluation of lipoprotein-cholesterol after fractionation of 20 microliter of serum in agarose electrophoresis in a discontinuous buffer system. The prestained lipoprotein bands are separated in less tha 1 h, cut out and extracted with butanol. The cholesterol in the extract is measured by a simple colorimetric method. The recoveries of lipoprotein cholesterol were 95.3% +/- 13.0 (S.D.), and the average coefficient of variation was 8% for alphalipoprotein, 6.4% for betalipoprotein and 8.0% for pre-betalipoproteins. Lipoprotein cholesterol concentrations, determined by the proposed method correlated well with those analyzed following ultracentrifugation. The method can handle up to 4 serum samples run in duplicate per day and only requires equipment available in conventional clinical laboratories, and stable reagents.

Adult↗