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J Vendrell

Publications and source records attributed to J Vendrell.

At least 19 recordsLinked to original sources
PubMed1992

Comparison of the NMR solution structure with the X-ray crystal structure of the activation domain from procarboxypeptidase B.

The NMR solution structure of the activation domain isolated from porcine procarboxypeptidase B is compared with the X-ray crystal structure of the corresponding segment in the intact proenzyme. For the region of the polypeptide chain that has a well-defined three-dimensional structure in solution, i.e., the backbone atoms of residues 11-76 and 25 amino acid side chains in this segment that form a hydrophobic core in the activation domain, the root-mean-square distance between the two structures is 1.1.A. There are no significant differences in average atom positions between the two structures, but only the NMR structure shows increased structural disorder in three outlying loops located along the same edge of the activation domain. These regions of increased structural disorder in the free domain coincide only partially with the interface to the enzyme domain in the proenzyme.

Amino Acid Sequence↗
PubMed1992

Non-association between 9.2 KB PvuII RFLP and seronegative spondyloarthropathies in Spain.

Several studies of DNA restriction fragment length polymorphism (RFLP) in ankylosing spondylitis (AS) have been carried out. The association between a recently identified class I HLA 9.2 kb PvuII RFLP and AS remain controversial. In order to evaluate this possible association in an Euro-Caucasian population, the genomic DNA of 42 AS patients and 18 patients with Reiter's syndrome (RS) and 42 healthy controls was analysed. Non-association between 9.2 kb PvuII RFLP and AS or RS was observed. As described previously, a strong association between this fragment and HLA-A3 and/or HLA-A9 antigens was demonstrated. A study of two families showed that this RFLP segregates with HLA-A3 and/or HLA-A9 and independently of the HLA-B27. Our findings support the view that the 9.2 kb PvuII fragment is not universally associated with AS.

Arthritis, Reactive↗
PubMed1992

Pancreatic procarboxypeptidases: their activation processes related to the structural features of the zymogens and activation segments.

The molecular events leading to the complete activation of pancreatic procarboxypeptidases A and B have been investigated. For both proteins the activation process follows a similar general scheme: trypsin is responsible for the first cleavage that separates the active enzyme from the activation segment, the degradation of the activation segment proceeds only from its C-terminal end, and activity release can be correlated with the disappearance of the long forms of the activation segment. In both systems, trypsin and the released carboxypeptidase participate in the trimming of the severed activation regions. However, the rate of enzymatic activation is much faster in the case of procarboxypeptidase B. This phenomenon may be explained by some structural differences in the connecting region which acts as a linker between the globular domain of the activation segment and the N-terminal end of carboxypeptidases and also by the higher efficiency of carboxypeptidase B for the digestion of its own activation segment. It is not due to unfolding of the activation domain, since the isolated activation domain retains its globular conformation in solution.

Amino Acid Sequence↗
PubMed1991

Differential scanning calorimetric study of carboxypeptidase B, procarboxypeptidase B and its globular activation domain.

High-sensitivity differential scanning calorimetry has been applied to the study of porcine pancreatic carboxypeptidase B, the proenzyme and its 81-residue activation domain. The thermal study has been carried out over a range of scan rates, ionic strengths and pH values. The thermal unfolding of the isolated activation domain has been found to be reversible and corresponds to that of a typical compact globular structure, with melting temperatures higher than those of the enzyme and proenzyme. Both proteins, on the other hand, undergo an irreversible, highly scan-rate-dependent thermal denaturation under all the experimental conditions investigated. The denaturation of the enzyme at pH 7.5 and the proenzyme at pH 7.5 and 9.0 follows the two-state irreversible model [Sánchez-Ruiz, J.M., López-Lacomba, J.L., Cortijo, M. & Mateo, P.L. (1988) Biochemistry 27, 1648-1652]. Thus the kinetic constants and activation parameters of the denaturation process could be obtained and compared to those for other proteins, particularly those of the closely related carboxypeptidase A system.

Animals↗
PubMed1991

The NMR structure of the activation domain isolated from porcine procarboxypeptidase B.

The three-dimensional structure of the activation domain isolated from porcine pancreatic procarboxypeptidase B was determined using 1H NMR spectroscopy. A group of 20 conformers is used to describe the solution structure of this 81 residue polypeptide chain, which has a well-defined backbone fold from residues 11-76 with an average root mean square distance for the backbone atoms of 1.0 +/- 0.1 A relative to the mean of the 20 conformers. The molecular architecture contains a four-stranded beta-sheet with the polypeptide segments 11-17, 36-39, 50-56 and 75-76, two well defined alpha-helices from residues 20-30 and 60-70, and a 3(10) helix from residues 43-46. The three helices are oriented almost exactly antiparallel to each other, are all on the same side of the beta-sheet, and the helix axes from an angle of approximately 45 degrees relative to the direction of the beta-strands. Three segments linking beta-strands and helical secondary structures, with residues 32-35, 39-43 and 56-61, are significantly less well ordered than the rest of the molecule. In the three-dimensional structure two of these loops (residues 32-35 and 56-61) are located close to each other near the protein surface, forming a continuous region of increased mobility, and the third disordered loop is separated from this region only by the peripheral beta-strand 36-39 and precedes the short 3(10) helix.

Amino Acid Sequence↗
PubMed1990

Autolysis of proproteinase E in bovine procarboxypeptidase A ternary complex gives rise to subunit III.

Extracts of bovine pancreatic tissue are shown by HPLC to contain two distinct ternary complexes of procarboxypeptidase A (subunit I), chymotrypsinogen C (subunit II) and either proproteinase E or subunit III. It is shown that proproteinase E in the complex generates subunit III by removal of 13 N-terminal residues when the former is allowed to autolyze in solution or when catalytic amounts of isolated active proteinase E are added to it. Autolysis of proproteinase E was accompanied by the loss of potential activity towards specific synthetic substrates and occurred at a higher rate in pancreatic juice than in pancreatic tissue extracts, even when both were processed in the presence of serine protease inhibitors. We conclude that subunit III (also called truncated protease E) is an autolytic product of proproteinase E and not an ab initio component of the native ternary complex.

Amino Acid Sequence↗
PubMed1990

Sequence-specific 1H NMR assignments and determination of the secondary structure for the activation domain isolated from pancreatic procarboxypeptidase B.

Nearly complete sequence-specific 1H NMR assignments are presented for amino acid residues 3-81 in the 81-residue globular activation domain of porcine pancreatic procarboxypeptidase B isolated after limited tryptic proteolysis of the zymogen. These resonance assignments are consistent with the chemically determined amino acid sequence. Regular secondary structure elements were identified from nuclear Overhauser effects and the sequence locations of slowly exchanging backbone amide protons. The molecule contains two alpha-helices, including residues 20-30 and approximately residues 58-72, and a three-stranded antiparallel beta-sheet with the individual strands extending approximately from 12 to 17, 50 to 55, and 75 to 77. The identification of these secondary structures and a preliminary analysis of additional long-range NOE distance constraints show that isolated activation domain B forms a stable structure with the typical traits of a globular protein. The data presented here are the basis for the determination of the complete three-dimensional structure of activation domain B, which is currently in progress.

Amino Acid Sequence↗
PubMed1990

The tryptic activation pathway of monomeric procarboxypeptidase A.

Procarboxypeptidases are the remaining major digestive zymogens the activation process of which remains unsolved. Here it is shown that in the tryptic activation of monomeric procarboxypeptidase A from porcine pancreas, the generation of carboxypeptidase A (CPA) activity parallels the limited proteolysis of the 94-residue activation segment. This degradation proceeds from the COOH-terminal end of the molecule, and CPA itself makes an important and unexpected contribution by excising the COOH-terminal arginine residue of the released primary activation fragment. Successive cleavages at some of the peptide bonds of the activation segment nearest to the COOH terminus were found to be of prime importance in eliciting CPA activity, particularly those involving the carbonyl groups of Arg94 and Gly93 which were first cleaved. It is also shown that the rate of activation does not depend directly upon the generation of CPA-alpha and its conversion to CPA-beta.

Amino Acid Sequence↗
PubMed1990

1H-n.m.r. studies of the isolated activation segment from pig procarboxypeptidase A.

The isolated activation segment (asA) from pig pancreatic procarboxypeptidase A was studied by 1H-n.m.r. spectroscopy over a wide range of solution conditions. Isolated asA shows many characteristics of compactly folded globular proteins, such as the observation of perturbed positions for resonances from methyl groups, alpha-carbon atoms, histidine residues and the tyrosine residue. The single tyrosine residue (Tyr-70) exhibits a very high pKa, and both histidine and tyrosine residues show slow chemical modification (deuteration and iodination). In contrast, asA shows rapid NH exchange. Analysis of the spectra by pH titration and nuclear Overhauser effects revealed several residue interactions. Quantitative analysis of deuterium and tritium exchange allowed the assignment of the histidine C-2-H resonances to their respective residues in the sequence. His-66, the closest to the sites of proteolytic attack in the proenzyme, is shown to be the most accessible to solvent in procarboxypeptidase A. It was also shown that asA is thermally very stable ['melting' temperature (Tm) 88 degrees C] and requires a high urea concentration for denaturation (6.25 M, at pH 7.5). Evidence is presented for some degree of conformational flexibility in the premelting range, a feature that could be ascribed to the preponderance of helical secondary structure and to the lack of disulphide bridges. The free solution structure of asA is probably unchanged when it binds to carboxypeptidase A.

Animals↗
PubMed1990

Human insulin dosage and distribution at the onset of type 1 diabetes mellitus.

The total insulin dosage and its distribution throughout the day were evaluated in newly diagnosed Spanish IDDM patients treated with semisynthetic human insulin. We assessed the insulin dosage and its distribution modifications related to an inpatient versus outpatient setting. We compared our results with classical theoretical algorithms based on patients treated with animal insulin and with alimentary habits which differ from our geographical area. The initial total daily dose (0.68 +/- 0.27 U/kg per day) did not substantially differ from the usual recommended dose (0.70-0.80 U/kg per day). A substantial decrease in total insulin dose was observed in ambulatory patients (0.55 U/kg per day). The reduction in dosage when we substituted regular insulin for intermediate acting insulin was smaller than what is commonly advised. A very low proportion of patients needed to add extra regular insulin to the pre-dinner intermediate insulin dose to achieve acceptable glucose control. Moreover, in these cases regular insulin comprised only 10% of total daily dosage, a proportion clearly inferior to that recommended. The majority of this group of patients needing regular insulin plus intermediate insulin at pre-dinner were treated with human zinc insulin. Most of our patients were acceptably controlled with a regular insulin dose before breakfast and lunch and an intermediate dose before dinner. Finally, human insulin pharmacokinetics plus our Mediterranean alimentary habits might be the explanation to our findings.

Adolescent↗
PubMed1990

Primary intrapulmonary benign schwannoma. A case with ultrastructural and immunohistochemical confirmation.

Neurogenic pulmonary tumours are rare. Neurofibromas are the most common variety and tend to occur in patients with generalized neurofibromatosis, whereas schwannomas arise sporadically in patients who have no evidence of this disorder. A case of solitary benign schwannoma arising in a segmental bronchus is presented, and the published cases reviewed. Microscopically, the tumour had a spindle-shaped cell proliferation with palisade formation in several fields and low cellularity in other areas. The diagnosis was supported by positive immunostaining for S-100 protein and by ultrastructural examination which showed elongated cells surrounded by well-preserved basal lamina and numerous cytoplasmic processes also possessing a basal lamina.

Aged↗
PubMed1989

[Evaluation of the treatment of Cushing's syndrome using ketoconazole].

The effectiveness of ketoconazole for the therapy of Cushing's syndrome, both of adrenal and pituitary origin, was retrospectively evaluated. To this end, the clinical and hormonal results in 5 patients were assessed. There were 4 females and one male, with ages ranging between 17 and 64 years. Three of them, who had Cushing's disease, received sustained treatment with ketoconazole when other therapeutic measures had failed. The two remaining patients (one with Cushing's disease and the other with adrenal adenoma) were treated with this drug in the preoperative period to alleviate the deterioration in the clinical condition caused by hypercortisolism. The clinical evolution of the patients is described, as well as the plasma adrenocorticotropin (ACTH) and the free cortisol in 24 hour urine in the subsequent controls. In view of the study results, we feel that ketoconazole is an effective treatment for the long term control of Cushing's syndrome. In addition, it may be also useful as preoperative therapy in those patients severely deteriorated by the sustained hypercortisolism.

Adolescent↗
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

[Cushing's disease in a patient with primary empty sella turcica].

Primary empty sella is a neuroanatomical condition which is more common in middle aged obese multiparous females with long-standing hypertension. Usually there are no symptoms, but occasionally nonspecific headache may be present. Hormone studies are commonly normal in these patients, although several functional hypothalamic and pituitary abnormalities have been reported. We report a 64-year-old female with primary empty sella in whom Cushing's disease was diagnosed. The association of both disorders is exceptional.

Cushing Syndrome↗
PubMed1989

Late-onset hypocalcemia appearing years after thyroid surgery.

We revised four cases of hypocalcemia diagnosed yr after thyroid surgery, including 1 man and 3 women, operated 5-23 yr before the onset of symptoms, which ranged from mild paresthesia to convulsive seizures. Total serum calcium levels ranged from 1.1 to 2.05 mmol/l, and PTH levels were low in the 3 cases in which they were measured. Hypoparathyroidism appearing as late-onset hypocalcemia after extense thyroid surgery is a poorly understood condition, perhaps not as unfrequent as it is considered.

Adult↗