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T Gonzales

Publications and source records attributed to T Gonzales.

10 recordsLinked to original sources
PubMed2005

[HLA-B27 polymorphism and spondyloarthropathies].

The association of HLA-B27 with ankylosing spondylitis (AS), and other spondyloarthropathies (SpA), remains as one of the strongest between HLA molecules and human disease. Since it was reported, in 1973, it has been extensively studied in order to understand the underlying pathogenic mechanism. The objective of this article is to review the current knowledge on the structure and polymorphism of HLA-B27 molecule, as well as describe the main pathogenic hypotheses trying to explain its association with AS.

HLA-B27 Antigen↗
PubMed1996

Bacterial aminopeptidases: properties and functions.

Aminopeptidases are exopeptidases that selectively release N-terminal amino acid residues from polypeptides and proteins. Bacteria display several aminopeptidasic activities which may be localised in the cytoplasm, on membranes, associated with the cell envelope or secreted into the extracellular media. Studies on the bacterial aminopeptide system have been carried out over the past three decades and are significant in fundamental and biotechnological domains. At present, about one hundred bacterial aminopeptidases have been purified and biochemically studied. About forty genes encoding aminopeptidases have also been cloned and characterised. Recently, the three-dimensional structure of two aminopeptidases, the methionine aminopeptidase from Escherichia coli and the leucine aminopeptidase from Aeromonas proteolytica, have been elucidated by crystallographic studies. Most of the quoted studies demonstrate that bacterial aminopeptidases generally show Michaelis-Menten kinetics and can be placed into either of two categories based on their substrate specificity: broad or narrow. These enzymes can also be classified by another criterium based on their catalytic mechanism: metallo-, cysteine- and serine-aminopeptidases, the former type being predominant in bacteria. Aminopeptidases play a role in several important physiological processes. It is noteworthy that some of them take part in the catabolism of exogenously supplied peptides and are necessary for the final steps of protein turnover. In addition, they are involved in some specific functions, such as the cleavage of N-terminal methionine from newly synthesised peptide chains (methionine aminopeptidases), the stabilisation of multicopy ColE1 based plasmids (aminopeptidase A) and the pyroglutamyl aminopeptidase (Pcp) present in many bacteria and responsible for the cleavage of the N-terminal pyroglutamate.

Amino Acid Sequence↗
PubMed1996

Mutational analysis of the active site of Pseudomonas fluorescens pyrrolidone carboxyl peptidase.

On the basis of chemical inhibition studies and a multiple alignment of four pyrrolidone carboxyl peptidase (Pcp) amino acid sequences, seven conserved residues of the Pseudomonas fluorescens Pcp, which might be important for enzyme activity, have been modified by site-directed mutagenesis experiments. Wild-type and mutant Pcps were expressed in Escherichia coli, purified, and characterized by the ability to cleave the synthetic chromogenic substrate pyroglutamyl-beta-naphthylamide and the dipeptide pyroglutamyl-alanine. Substitution of Glu-10 and Glu-22 by Gln led to enzymes which displayed catalytic properties and sensitivities to 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide similar to those of the wild-type Pcp. These residues are not essential for the catalytic activity. Replacement of Asp-89 by Asn and Ala resulted in enzymes which retained nearly 25% of activity and which had no activity, respectively. Substitution of the Cys-144 and His-166 residues by Ala and Ser, respectively, resulted in inactive enzymes. Proteins with changes of Glu-81 to Gln and Asp-94 to Asn were not detectable in crude extract and were probably unstable in bacteria. Our results are consistent with the proposal that Cys-144 and His-166 constitute the nucleophilic and imidazole residues of the Pcp active site, while residue Glu-81, Asp-89, or Asp-94 might constitute the third part of the active site. These results lead us to propose Pcps as a new class of thiol aminopeptidases.

Amino Acid Sequence↗
PubMed1994

Characterization of the pcp gene of Pseudomonas fluorescens and of its product, pyrrolidone carboxyl peptidase (Pcp).

The gene pcp, encoding pyrrolidone carboxyl peptidase (Pcp), from Pseudomonas fluorescens MFO was cloned and its nucleotide sequence was determined. This sequence contains a unique open reading frame (pcp) coding for a polypeptide of 213 amino acids (M(r) 22,441) which has significant homology to the Pcps from Streptococcus pyogenes, Bacillus subtilis, and Bacillus amyloliquefaciens. Comparison of the four Pcp sequences revealed two highly conserved motifs which may be involved in the active site of these enzymes. The cloned Pcp from P. fluorescens was purified to homogeneity and appears to exist as a dimer. This enzyme displays a Michaelis constant of 0.21 mM with L-pyroglutamyl-beta-naphthylamide as the substrate and an absolute substrate specificity towards N-terminal pyroglutamyl residues. Studies of inhibition by chemical compounds revealed that the cysteine and histidine residues are essential for enzyme activity. From their conservation in the four enzyme sequences, the Cys-144 and His-166 amino acids are proposed to form a part of the active site of these enzymes.

Amino Acid Sequence↗
PubMed1990

[Blood pressure variability and morbidity].

In a previous study (resting blood pressure profile, Dinamap) we have confirmed the correlations between blood pressure and left ventricular mass (myocardial hypertrophy being one of the morbidity criteria in Hypertension) and we have demonstrated the absence of significant difference (Fisher's z Test) with the results of ambulatory recordings found in literature. Furthermore, we have showed a weaker correlation between absolute variability (AV) and left ventricular mass (LVM). If indeed there exists a cause-effect relationship between the AV increase and the LVM increase, a relative independence between VA and blood pressures mean (mBP) should still be demonstrated. In order to do that we have used the factorial analysis (main components analysis) with which a small number of independent factors can be isolated from a large number of correlated variables. A resting blood pressure (Dinamap, 8AM-8PM, one reading every 15 minutes) has been recorded among 551 patients (259 females, 292 males; 109 normotensive WHO, 442 hypertensive WHO) and an echocardiogram TM and two-dimensional in order to measure the interventricular septum thickness (IVST), the posterior wall thickness (PWT) and the left ventricular internal diameter (LVID) with which we can calculate the myocardial mass (MM, Devereux formula) and the myocardial mass index (MMI) using the body surface (BS). The blood pressure variables are the means of the recordings (mBP): systolic (mSBP), diastolic (mDBP), mean (mMBP) and their standard deviations (SSD, DSD, MSD) corresponding to the AV. We have studied the heart rate (HR) with its standard deviation (HRSD) and age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Relationship between heart mass and semi-ambulatory pressure profiles].

This work was undertaken with 420 patients (90 normotensives: casual blood pressure less than or equal to 140/90 mmHg and 330 hypertensives) in which was recorded a semi ambulatory blood pressure profile (Dinamap 8AM-8PM, a reading every fifteen minutes). On the same day an echocardiogram was performed. We have correlated the left ventricular mass, the left ventricular mass index, the interventricular septum, the left ventricular cavity volume and the left ventricular posterior wall with casual blood pressure, average daily blood pressure standard deviation and variation coefficient for mean blood pressure, systolic blood pressure and diastolic blood pressure. Analysis by sex, left ventricular mass index and blood pressure level (normotensive, hypertensive): we observe a left ventricular hypertrophy in normotensive males (18 p. 100) and hypertensive ones (39.8 p. 100), in normotensive females (15 p. 100) and hypertensive ones (33.3 p. 100). Overall in 420 patients: excellent correlation (p less than 0.001) between average daily blood pressure, casual blood pressure and the four echocardiographic parameters except for left ventricular cavity volume. But correlation is better (z test of Fisher) with average daily blood pressure than with casual blood pressure. No difference exists between results obtained in women (194) and men (226). Concerning variability, four observations: there exists a correlation between standard deviation, left ventricular mass index, interventricular septum, left ventricular posterior wall (only for standard deviation of MBP). No correlation with coefficient correlation except for the MBP with septum in women. The correlation for the standard deviation are weaker than with average daily blood pressure. They are better with the septum than with other echocardiographic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Bioimpedance or anthropometry?

The ability of bioimpedance (BIA) to predict body composition in comparison with anthropometric measurements (weight and height) was assessed on three groups of adult young women (n = 99) and one group of adult young men (n = 49). Body fat (BF) and fat-free mass (FFM) by densitometry were used as the reference data. Resistance and reactance separately or together were poor predictors of BF and FFM, explaining from 0 to a maximum of 21 per cent of the FFM variation in the different groups. BF followed the same pattern, though the percentage of variance explained by both variables was even lower. Height squared divided by resistance (H2/R) explained from 22 to 68 per cent of the FFM variation and from 0 to 40 per cent of BF variation. Height alone was comparable to H2/R explaining from 11 to 53 per cent of the FFM variance in the four groups studied. Body weight was found to be the best single predictor of body composition; it explained from 56 to 78 per cent of FFM and 37 to 82 per cent of BF variability. Using stepwise regression analysis with all women combined, weight accounted for 70 per cent of the total FFM variation, with height and H2/R contributing only another 5 per cent. The same was found in men (68 vs 73 per cent respectively). The reported equation of Segal et al. was applied to our group, yielding almost the same high FFM prediction (r2 greater than 0.7 and SEE less than 2.5 kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1986

[Total or partial electrical interruption of the atrioventricular pathway. Evaluation of clinical results and indications].

After checking on the efficacy and innocuity of catheter ablation of the His bundle in an experimental study in the sheep, 22 patients with supraventricular tachycardia resistant to an average of 5.5 +/- 1.7 antiarrhythmic drugs per patient underwent this procedure. The most common arrhythmias were atrial fibrillation or flutter (poorly tolerated in 14 cases), and reciprocating tachycardia (8 cases, including 3 with accessory atrioventricular pathways). In 3 of the 5 patients with intranodal tachycardia, an initial attempt was made to modify one of the two AV nodal conduction pathways. Although complete atrioventricular block was obtained in all patients, atrioventricular conduction returned in 15 patients between the 30th minute and 4th day after the procedure. A second attempt at His bundle ablation was carried out in 9 patients. During follow-up ranging from 1 to 38 months, complete or an advanced degree of atrioventricular block persisted in 5 patients, the other patients being in sinus rhythm (12 cases) or slow atrial fibrillation (2 cases). The remaining patient who was in complete atrioventricular block died of septicaemia 2 months after the procedure. The clinical results were evaluated by electrophysiological investigation, exercise testing and Holter monitoring. There were 15 satisfactory clinical results (83.3 p. 100) and 3 poor results. This series shows that interruption or modification of the normal atrioventricular conduction pathway may be performed at low risk and with good results in a high percentage of cases. It is a valuable therapeutic option in patients with supraventricular tachycardia resistant to antiarrhythmic therapy.

Adult↗