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Biomedical subjects

R Pascual

Publications and source records attributed to R Pascual.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Mycobacterium fortuitum in patients with chronic renal insufficiency: apropos of 2 cases].

Mycobacterium fortuitum is a rapidly growing mycobacteria recovered from human infections such as skin, soft tissue, skeletal and pulmonary infectious diseases. We report 2 cases of M. fortuitum isolation from clinical samples from two patients placed on dialysis program. Our clinical findings were: The first, the presence of an abscess in the area of insertion of a CAPD catheter and the second, the detection of a lobar pneumonia in a patient placed on long-term hemodialysis program. We consider this report to be important because of the few reported cases of non tuberculous mycobacterial infections in patients with chronic renal failure.

Abscess↗
PubMed1990

[Diffuse melanosis in metastatic malignant melanoma with melanuria].

We report an additional case of diffuse melanosis secondary to metastases from malignant melanoma in a patient, who was seen in our department shortly before death. We couldn't localize the origin of the primary neoplasm. After reporting the case, we discuss the pathogenesis of melanosis and possible sites of the primary tumor.

Aged↗
PubMed1989

The separation of pancreatic procarboxypeptidases by high-performance liquid chromatography and chromatofocusing.

Different experimental conditions and chromatographic supports have been selected for the most efficient and rapid purification of procarboxypeptidases from porcine and human pancreas by different high-performance liquid chromatography (HPLC) variants (anion exchange, reversed phase and gel filtration). Anion-exchange chromatography was found to be the most capable and permitted the isolation, in a single step, of three different porcine procarboxypeptidases (2A + 1B forms) and five different human procarboxypeptidases (2B + 3A forms) in a native and pure state from whole pancreas extracts. Other pancreatic proproteases are also cleanly isolated in the same step. Reversed-phase chromatography under mild conditions separated porcine or human procarboxypeptidases A from other pancreatic proteins in a very short time but was unable further to subfractionate the same proteins. The sequential use of gel filtration (or anion-exchange) and reversed-phase HPLC chromatography permitted, in a simple way, the isolation and dissociation of the strongly bound components of the binary complexes between procarboxypeptidases A and proproteinase E in either porcine or human pancreas extracts. Chromatofocusing on a fast protein liquid chromatographic support was also found to be a very efficient technique, showing a slightly lower capability to separate procarboxypeptidases than anion-exchange HPLC though in a much shorter time and in larger quantities.

Animals↗
PubMed1989

Generation of a subunit III-like protein by autolysis of human and porcine proproteinase e in a binary complex with procarboxypeptidase A.

Tryptic treatment of human and porcine proproteinase E, procarboxypeptidase A binary complexes gave rise to active proteinase E after removal of an 11-residue N-terminal activation peptide. By contrast, upon treatment of either complex with active proteinase E, not only was the activation peptide released but also the hydrophobic dipeptide Val12-Val13 of the corresponding enzyme. No serine protease activity on specific synthetic peptide substrates could be detected. The structural homology of inactive proteinase E with subunit III of ruminant procarboxypeptidase A was strengthened by the existence of a functional homology since truncated proteinase E still possessed a weakly functional active site. Thus, subunit III-like proteins are generated by proteinase E-catalyzed limited proteolysis of proproteinase E.

Amino Acid Sequence↗
PubMed1989

Modification by indomethacin of airway contractile responses in normal and sensitized guinea-pigs.

Active sensitization of guinea-pigs resulted in an increase in responsiveness and sensitivity of tracheal and lung parenchymal strips to CaCl2 (in K+-depolarised tissue), KCl, acetylcholine and histamine. Indomethacin (5 microM) preferentially enhanced the response of tracheal strips from normal animals to histamine and to a lesser extent acetylcholine but not to CaCl2 or KCl. A similar trend was observed in sensitized tissues. Indomethacin pretreatment did not cause changes in responsiveness or sensitivity of lung parenchymal strips from normal or sensitized guinea-pigs to the agonists tested. It is concluded that immunological sensitization produced a non-specific hyperresponsiveness in trachea and lung parenchymal strips. Conversely, cyclooxygenase inhibition by indomethacin elicited a selective increase in the responsiveness to certain agonists in central but not in the peripheral airways.

Animals↗
PubMed1989

Purification and properties of five different forms of human procarboxypeptidases.

Three different procarboxypeptidases A and two different procarboxypeptidases B have been isolated for the first time, in a pure and native state, from human pancreatic extracts. These proteins were purified in one or two quick steps by anion-exchange HPLC. All these forms have been biochemically characterized. Two of the procarboxypeptidases A, the A1 and A2 forms, are obtained in a monomeric state while the other, the A3 form, is obtained as a binary complex of a procarboxypeptidase A with a proproteinase E. This complex is stable in aqueous buffers at various ionic strengths and develops carboxypeptidase A and proteinase E activities in the presence of trypsin. The A1 and A2 forms show clear differences in electrophoretic mobility in SDS/polyacrylamide gels, isoelectric point, proteolytic activation process with trypsin and susceptibility to thermal denaturation. In contrast, these properties are similar in the A1 and A3 (binary complex) forms. On the other hand, with respect to the properties listed above, the B1 and B2 forms differ from each other mainly in isoelectric point. An overall comparison of the above properties reveals the unusual character of the A2 form, midway between the other A and B forms. N-terminal extended sequence analysis carried out on these proenzymes confirm that they constitute different isologous forms.

Animals↗
PubMed1989

Action of methylene blue and haemoglobin in rabbit aorta in relation to the surface of drug entry.

The effect of methylene blue and haemoglobin has been evaluated by using a procedure of restricting drug entry to one surface of rabbit aortic rings. In preparations precontracted with noradrenaline, methylene blue and haemoglobin produced, via the intima, an additional rapid and endothelium-dependent contraction. While haemoglobin was without effect via the adventitia, methylene blue produced a slow endothelium-independent contraction that was diminished but not abolished in reserpine-pretreated animals. This augmentation of the noradrenaline-induced contraction produced by methylene blue via the adventitia in reserpine-pretreated rabbits was observed also with phenylephrine but not with methoxamine. Methylene blue, when added to aortic rings incubated with 3H-(-)-noradrenaline, interfered with the neuronal uptake of this amine and enhanced the outflow of 3H. In conclusion, methylene blue and haemoglobin enhanced noradrenaline-induced contraction by an endothelium-dependent mechanism when applied via the intima. Haemoglobin is devoid of effects via the adventitia but methylene blue has indirect sympathomimetic effects. In experiments using intact rings with no restriction to drug entry it was found that the enhancement by haemoglobin of the tyramine-induced response was markedly less than that observed for noradrenaline for the same level of plateau contraction. This finding indicates that the endothelium-derived relaxing factor is more effective on smooth muscle cell layers in the vicinity of intima than on those close to adventitia.

Animals↗
PubMed1989

[Physical exercise and serum potassium in renal insufficiency].

In order to study the effect of physical exercise on serum potassium in renal failure, twelve patients currently on chronic dialysis were subjected to physical exercise by means of an ergometric bicycle. The initial serum potassium was 5.2 +/- 0.6 mmol/l and after the performance of 3.304 +/- 1.583 kilopondimeters of total work, serum potassium was not modified: 5.5 +/- 0.6 mmol/l (p = NS). With regard to the parameters that regulate the intra-cellular distribution of serum potassium, physical exercise aggravated metabolic acidosis, decreasing the blood pH: from 7.33 +/- 0.05 to 7.23 +/- 0.08 (p less than 0.01) and plasma bicarbonate: from 19 +/- 3 mmol/l to 14 +/- 4 mmol/l (p less than 0.01); this was accompanied by a significant and percentage-wise similar increase in plasma epinephrine and norepinephrine. Patients with end-stage renal failure can perform moderate physical exercise, since this does not produce significant changes in serum potassium.

Adult↗
PubMed1988

EEG maturation on children with different economic and psychosocial characteristics.

It has been shown that EEG maturation can be described in terms of regression equations on age of broad band EEG frequency parameters. In the present paper six groups of children with different economic and psychosocial characteristics of three countries were studied. Regression equations on age of the EEG relative power (expressed in percentages of the total EEG activity) in the delta, theta, alpha and beta bands in 8 bipolar derivations were computed in each group of children and the slopes compared with those previously published by John et al. (1980). Those children who grew up with adequate nutritional, sanitary and cultural environmental conditions showed the same slopes as U.S. and Swedish children selected with strict criteria of normality. Children nourished in poor socioeconomic and sanitary environments and who frequently had pathological personal antecedents with risk factors associated with brain damage showed either a slow maturation of the EEG characterized by smaller slopes of theta relative power or a great variance of EEG parameters and no relation of these parameters to age.

Child↗
PubMed1987

EEG developmental equations confirmed for Cuban schoolchildren.

Previous authors have reported developmental equations that describe the variation with age of broad-band spectral parameters (BBSPs) obtained from bipolar EEG derivations. It has been argued that the equations, originally obtained for American children, are relatively independent of socio-cultural variables. In this paper the transcultural validity of these equations is demonstrated by means of an independent validation of the BBSP equations for a sample of Cuban schoolchildren.

Brain↗
PubMed1985

Responses of rabbit aorta to tyramine in relation to the surface of drug entry.

The contraction elicited by submaximally effective concentrations of tyramine in the rabbit aortic strip occurs after a shorter latency and increases at a higher initial velocity to a greater steady-state level when drug entry is limited to the adventitial than when it is limited to the intimal surface. The reverse was true for noradrenaline. Both amines elicited equal maximum responses with independence of the surface of entry into the vascular wall. Differences between steady-state contractions disappear when the intramural disposition pathways of tyramine are blocked pharmacologically by a combination of pargyline and semicarbazide. Incubation with cocaine and pretreatment with reserpine resulted in a reversal of the surface of entry related differences between steady-state contractions to tyramine related to differences of the surface of entry. This reflected the unmasking of the direct component of the action of tyramine. Thus, the technique of limited drug entry into the vascular wall together with blockade of disposition pathways allows us to characterize the pre- and postsynaptic components of the action of tyramine.

Animals↗