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Biomedical subjects

J Vendrell

Publications and source records attributed to J Vendrell.

101 records · Page 6Linked to original sources

Erythromelalgia associated with acute diabetic neuropathy: an unusual condition.

Erythromelalgia is a syndrome characterized by erythema, burning pain and increased skin temperature of the affected extremities. It can be either primary (idiopathic) or secondary, but both forms require a critical temperature between 32-36 degrees C to provoke the crisis. Among the secondary forms, its association with diabetes mellitus is infrequent and its significance is little known. The histological studies have been fundamentally performed in patients with this syndrome affected by thrombocythemia; vascular thrombosis and fibromuscular intimal arteriolar proliferation were the prominent findings not corroborated in patients with the primary form. We studied one patient with acute diabetic neuropathy who developed erythromelalgia. We noted the absence of histopathological lesions, suggesting a disorder in vascular motility regulation favored by the severe neuropathy, without being able to discount a possible immunomediated mechanism. We describe the favourable evolution of the patient after treatment with aspirin and methysergide.

Acute Disease↗

Conformational predictive studies on the activation segment of pancreatic procarboxypeptidases.

Little is known about the conformation and evolutionary origin of the activation segment of pancreatic procarboxypeptidases. Analysis of the sequence and secondary structure propensities of these propeptide segments indicate that they contain two regions structurally related to the Ca2+-binding sites of the EF-hand protein family. This proposed homology could explain how (and why) carboxypeptidases developed such long (94 residues) activation peptides.

Animals↗

Primary structure of the activation segment of procarboxypeptidase A from porcine pancreas.

The complete primary structure of the activation segment of monomeric procarboxypeptidase A from porcine pancreas has been determined by automated and manual Edman-like degradation methods performed on its fragments generated by enzymatic cleavage. The polypeptide consists of 94 residues, with a molecular mass of 10,768, and presents a high proportion of acidic and hydrophobic residues and a proline-rich region in the center of the molecule. Comparison of this sequence with the already reported equivalent sequence deduced from rat procarboxypeptidase A cDNA reveals a very high degree of homology between the two propeptides (up to a 81% of identities), which is even higher in certain large zones of the molecule.

Amino Acid Sequence↗

Preparative isolation of the two forms of pig pancreatic pro-(carboxypeptidase A) and their monomeric carboxypeptidases A.

A method is reported for the preparative isolation of the two forms of pro-(carboxypeptidase A) from pig pancreas: the monomer and the binary complex with pro-(proteinase E). This method, which is mainly based on chromatography on DEAE-Sepharose at pH 5.7, allows these proenzymes to be prepared more quickly and in safer conditions than with other reported methods. Undegraded and homogeneous carboxypeptidase A1 and A2 species (peptidyl-L-amino acid hydrolase, EC 3.4.17.1), in monomeric forms with high specific activity, are also obtained in high yield by controlled trypsin activation of either of the pro-(carboxypeptidases A) followed by chromatography on DEAE-Sepharose at pH 5.8 under dissociating conditions (7 M-urea).

Animals↗

Sequential homologies between procarboxypeptidases A and B from porcine pancreas.

Automated Edman degradation of monomeric procarboxypeptidases A and B from porcine pancreas shows that their N-terminal regions (from residue 1 to 34-37) present a high degree of sequential homology to each other as well as to other related procarboxypeptidases. Conformational predictions based on these sequences confirm their structural homology and indicate the probable existence of two beta-turns, one beta-chain and a long alpha-helix in them. On the other hand, tryptic peptide maps on a reverse-phase column indicate great sequential similarities (if not identity) between monomeric procarboxypeptidase A and the procarboxypeptidase A subunit isolated from its binary complex with proproteinase E.

Amino Acid Sequence↗

Isolation and re-association of the subunits from the pro-(carboxypeptidase A)-pro-(proteinase E) binary complex from pgi pancreas.

The component subunits of the pro-(carboxypeptidase A)-pro-(proteinase E) binary complex from pig pancreas were separated with a high recovery (80-95%) of their original potential activity. The isolated subunits and the reconstituted complex have properties similar to those of the corresponding natural species. The tryptic activation course of the pro-(carboxypeptidase A) subunit is substantially modified when bound to pro-(proteinase E), whereas the activation of pro-(proteinase E) is not dependent on this association.

Animals↗

Diversity of patterns of improvement in confrontation naming rehabilitation: some tentative hypotheses.

A previous group analysis of the effects of a computerized written naming rehabilitation program revealed global improvement with generalization of benefits to untrained items and to untreated oral naming (Deloche et al., 1992). The present multiple single-case analysis of the data indicates a variety of patterns of improvement and of generalization effects among individual patients. Patterns of relationships between written and oral naming behaviors help to explain the type of improvement that was observed.

Adult↗

Pancreatic procarboxypeptidases: oligomeric structures and activation processes revisited.

The activation peptides of procarboxypeptidases of the A1 type act in a post-activation mechanism of control, limiting the expression of activity immediately after the limited proteolysis has occurred. This effect is due to structural complementarity between the enzymatic moiety and the released fragments, and is further enhanced by the occurrence of procarboxypeptidase A1 in oligomeric complexes of different type depending on the species studied. In those complexes, the activation segment has an important role in the stabilisation of the quaternary structure. The relationship between oligomeric structure and activation is reviewed here for two of the most extensively studied systems.

Animals↗