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T Pérez

Publications and source records attributed to T Pérez.

At least 19 recordsLinked to original sources
PubMed2001

[Meconium in the amniotic fluid: prevention of meconium aspiration and elective tracheal suction].

For many years early systematic intubation and tracheal suction have been advocated for meconium-stained infants. Recent data show that they do not reduce the frequency of pulmonary meconium aspiration and underline the importance of a preventive attitude (i.e., intrapartum oropharyngeal suction before shoulder clearing and thoracic compression before first breathing) together with a selective tracheal suction only in the newborns with obvious oropharyngeal meconial staining.

Algorithms↗
PubMed2000

Differential scanning calorimetry study of the hydrophobic hydration of the elastin-based polypentapeptide, poly(VPGVG), from deficiency to excess of water.

The polypentapeptide of elastin, poly(VPGVG), has become an interesting model polypeptide in understanding the mechanism of protein folding and assembly. Due to its simple amino acid composition and the predominance of apolar side chains, this polymer shows strong hydrophobic-hydration phenomena. This paper explores, by calorimetric methods, the nature and structure of the clathrate-like arrangements that take place, surrounding the apolar side chains of the polymer. The performance of these methods, especially differential scanning calorimetry, has a well-gained reputation. In this work, the development of the clathrate-like structures around this model polymer has been followed from water deficiency to water-excess states. Two main conclusions have been obtained from the data obtained. First, there is an upper limit of about 170 water molecules per pentamer as the number of water molecules required to form all the possible clathrate-like structures. Second, these structures exist as an inhomogeneous population with energies spreading in a significantly broad range, which is likely related to differences in geometrical parameters (bond lengths and angles) of the clathrate structure.

Amino Acid Sequence↗
PubMed2000

Estimation of microsatellite mutation rates in Drosophila melanogaster.

Microsatellite mutations were studied in a set of 175 mutation accumulation lines, all of them independently derived from a completely homozygous population of Drosophila melanogaster and maintained under strong inbreeding during 80 generations. We assayed 28 microsatellites and detected two mutations. One mutation consisted of a single addition of a dinucleotide repeat and the other was a deletion of five trinucleotide repeats. The average mutation rate was 5.1 x 10(-6), in full agreement with previous estimates from two different sets of mutation accumulation lines.

Animals↗
PubMed2000

Effect of exogenous insulin and glucagon on exocrine pancreatic secretion in rats in vivo.

BACKGROUND: The physiological roles of the islet hormones insulin and glucagon in the control of exocrine pancreatic secretion is not clear. It is still unknown whether these hormones have a stimulatory or an inhibitory effect on the basal exocrine pancreatic secretion. METHODS: Thirty anesthetized rats were stimulated with doses of insulin and glucagon administered by continuous intravenous infusion. Doses varying from physiological to supraphysiological were used. Different groups of 5 rats were given each of these doses. The volume of pancreatic juice and amylase, lipase and trypsin activity, as well as enzyme output, were measured 0, 20, 40, and 60 min after starting infusion. The insulin, glucagon, and glucose levels were determined in serum at 0, 10, 30, and 60 min. RESULTS: In the insulin group, the secreted volume of pancreatic juice increases with the maximum dose. All insulin doses results in amylase and lipase decreased activity. When submaximum and maximum insulin doses are administered, the trypsin activity also decreases. In the glucagon group, the activity of lipase and trypsin decreases regardless the dose, whereas the amylase activity decreases with submaximum and supramaximum doses. CONCLUSION: Both insulin and glucagon affect the basal exocrine pancreatic secretion in vivo when physiological doses are administered.

Amylases↗
PubMed1998

An evaluation of RAPD fragment reproducibility and nature.

Random amplified polymorphic DNA (RAPD) fragment reproducibility was assayed in three animal species: red deer (Cervus elaphus), wild boar (Sus scrofa) and fruit fly (Drosophila melanogaster). Ten 10-mer primers (Operon) were tested in two replicate reactions per individual under different stringency conditions (annealing temperatures of 35 degrees C or 45 degrees C). Two estimates were generated from the data: autosimilarity, which tests the reproducibility of overall banding patterns, and band repeatability, which tests the reproducibility of specific bands. Autosimilarity (the similarity of individuals with themselves) was lower than 1 for all three species ranging between values of 0.66 for Drosophila at 45 degrees C and 0.88 for wild boar at 35 degrees C. Band repeatability was estimated as the proportion of individuals showing homologous bands in both replicates. The fraction of repeatable bands was 23% for deer, 36% for boar and 26% for fruit fly, all at an annealing temperature of 35 degrees C. Raising the annealing temperature did not improve repeatability. Phage lambda DNA was subjected to amplification and the pattern of bands compared with theoretical expectations based on nucleotide sequence. Observed fragments could not be related to expected ones, even if a 2 bp mismatch is allowed. Therefore, the nature of genetic variation uncovered by the RAPD method is unclear. These data demonstrate that prudence should guide inferences about population structure and nucleotide divergence based on RAPD markers.

Animals↗
PubMed1998

Subclavian vascular access stenosis in dialysis patients: natural history and risk factors.

Stenosis of the subclavian vein (SVS) after cannulation occurs in 15 to 50% of chronic hemodialysis patients, and impedes the placement of an arteriovenous fistula in the ipsilateral arm. Its natural history and pathogenic mechanisms are not well established. This study examined 42 consecutive chronic renal failure patients (28 men and 14 women; 46+/-19 yr) in whom subclavian catheters had been placed as the initial vascular access for hemodialysis. All patients underwent sequential venography studies: at baseline (24 to 48 h after removal of the catheter) and 1, 3, and 6 mo thereafter. Venograms were considered abnormal when there was evidence of unequivocal strictures (more than 30% narrowing), with or without collateral circulation. At baseline, 52.4% (n=22) of patients showed stenotic vein lesions (n=19) or total thrombosis (n=3), and identical lesions were also observed after 1 mo. Surprisingly, 10 of 22 patients with initial SVS (45.4%) showed spontaneous recanalization of venous lesions in the venographies performed 3 mo after removal. The patients with normal baseline venograms (n=20) showed no change during follow-up. Patients with definitive stenosis at 6 mo (n=12) had a higher number of inserted catheters (1.58+/-0.6 versus 1.2+/-0.48; P < 0.05), longer time in place (49.08+/-32.2 versus 29.03+/-26.6 d; P < 0.05), and higher number of dialysis sessions (21+/-13.8 versus 12.4+/-11.4; P < 0.05) than those without SVS or with spontaneous recanalization of venous lesions during follow-up. Furthermore, a higher number of catheter-related infections were observed in patients with definitive SVS (66.6% versus 33.3%; P < 0.05). In summary, SVS is observed in more than half of patients 24 to 48 h after catheter removal and 1 mo later. Even when recanalization occurs in many cases, a definitive stenosis is seen in 28% of patients by the third month. Thus, the creation of an ipsilateral vascular access is possible provided that venography is normal at this time. Finally, mechanical factors and catheter-related infections are the major risk factors for the development of late SVS.

Adult↗
PubMed1997

Development and maturation of noradrenaline-containing nerves of the rat uterine artery. Effects of acute and chronic oestrogen treatment.

The development and maturation of noradrenaline-containing nerves of the rat uterine artery was investigated, histochemically and biochemically, at seven different postnatal age-stages and following acute and chronic treatment with oestradiol. Morphological changes in the vessel were quantitatively evaluated on Toluidine Blue-stained semithin sections and low magnification electronmicrographs. In summary, the uterine artery is innervated at birth; the adult pattern of innervation is established at two weeks of age; the innervation density increases progressively between the infantile and prepubertal periods, accompanying proliferation and growth of smooth muscle cells in the tunica media; changes in the innervation are followed by an increase in the tissue concentration of noradrenaline and neither the endocrine changes characterizing puberty nor acute or chronic treatment with oestradiol have an effect on the pattern of development of the uterine artery and associated noradrenaline-containing nerves. Results are interpreted considering the differential susceptibility of urinogenital organs to sex hormones.

Animals↗
PubMed1996

Application of DNA fingerprinting to population study of chamois (Rupicapra rupicapra).

Hypervariable minisatellite DNA probes 33.15 and 33.6, originally developed for studies in human populations, were used to study genetic variation in chamois (Rupicapra rupicapra). The mean number of bands per individual was 25 for probe 33.15 and 15 for probe 33.6. The average band frequency was 0.33 for both probes. The mean similarity was 0.44, greater than that reported for human and natural populations and close to values found in domestic populations of mammals. This lack of variability could be related to the bottleneck suffered by the population due to large-scale hunting after the Spanish Civil War. Levels of variability are high compared with variability at the level of protein markers, so the use of minisatellite DNA is recommended for future population studies in this species. We did not find large genetic differences between subpopulations, indicating that the population is genetically homogeneous.

Animals↗
PubMed1996

[Is there a correlation between the values of breath tests and the response to the treatment for the eradication of Helicobacter pylori?].

PURPOSE: To study a possible correlation between the urea breath test values prior to treatment and the response to Helicobacter pylori eradication therapy in patients with duodenal ulcer. METHODS: Seventy-seven patients with duodenal ulcer were retrospectively studied (mean age: 46 +/- 13 years; 71% males). Initially, an endoscopy with biopsy samples (H&E stain) taken from antrum and body was performed, and a 13C-urea breath test (measuring 13C difference: delta 13CO2) was also performed. Both procedures were repeated one month after completing therapy ("classic" triple therapy [n = 25], and omeprazole plus amoxycillin [n = 52]). RESULTS: Eradication was achieved in 40% of cases (n = 32), and it was higher in patients treated with "classic" triple therapy (60%) than in those treated with omeprazole plus amoxycillin (31%) (p = 0.017). Mean delta 13CO2 level was 25 +/- 15. There were no differences when comparing values of patients with successful eradication (24 +/- 18) or therapy failure (25.6 +/- 13). No differences were observed when considering both therapies separately or when comparing eradication rates depending upon breath test levels prior to therapy. Breath test values did not influence the eradication in the logistic regression model. Mean delta 13CO2 values after therapy in patients with eradication failure ran in parallel with those observed previously. CONCLUSION: No correlation was observed between urea breath test values before treatment and the response to H. pylori eradication therapy in patients with duodenal ulcer. Thus, we conclude that quantification of this diagnostic method is not useful to predict the success or failure of eradicating therapy.

Amoxicillin↗
PubMed1994

Anticardiolipin antibodies in pediatric patients with human immunodeficiency virus.

OBJECTIVE: To study the presence of IgG and IgM anticardiolipin antibodies (aCL) in children with human immunodeficiency virus (HIV) infection and to determine their prevalence and clinical significance. METHODS: We studied 34 children with HIV infection: 26 patients were classified P-2, and 8 were P-1 according to the Centers for Disease Control classification. HIV transmission was from mother to child in 33 cases. aCL were measured by ELISA: RESULTS: IgG aCL were found in 28 (82%) and IgM aCL in 7 (20%). No difference in frequency and levels was found between class P-2 (85%, mean 54.5 PL units) and class P-1 (75%, mean 50.3 PL units). aCL were not related to the duration of the infection, clinical stage of disease, or with events like opportunistic infections. Children from sexually infected or intravenous drug user mothers showed no differences. CONCLUSION: As in adults, aCL are commonly found in children with HIV infection. The significance of this finding is still unclear.

Antibodies, Anticardiolipin↗
PubMed1994

Heterogeneity of the anti-Ro(SSA) response in rheumatic diseases.

OBJECTIVE: The immune response to the Ro(SSA) antigen is heterogeneous. Anti-Ro(SSA) positive sera may contain antibodies recognizing either a 60 or a 52 kDa polypeptide component of the Ro(SSA) particle. Thus we sought to determine the profile of anti-Ro(SSA) antibodies defined by immunoblotting in patients with rheumatic diseases. METHODS: Immunoblotting against human placenta extract and ELISA against recombinant Ro(SSA) antigen as confirmatory tests were done to detect anti-Ro(SSA) antibodies in 563 sera from patients with systemic lupus erythematosus (SLE). Sjögren's syndrome (SS), rheumatoid arthritis (RA) and other connective tissue diseases. RESULTS: Anti-52 kDa antibodies were more common in primary patients with SS (9/22; 40.9%) than in patients with SLE (29/135; 21.4%) or patients with RA (7/315; 2.2%). Anti-60 kDa antibodies were more frequent in patients with SLE (26/135; 19.2%) than in patients with primary SS (2/22; 9%) or RA (17/315; 5.3%). None of the 22 patients with primary SS had only antibodies to the 60 kDa polypeptide. Among the 153 patients whose sera were positive by ELISA, 73 (47.7%) were negative by immunoblotting. The most frequent diagnoses in these sera were RA and SLE. The anti-52 kDa sera had higher optical density values compared to anti-60 kDa sera. CONCLUSIONS: Our observations indicate the existence of qualitatively and quantitatively different anti-Ro(SSA) responses in the rheumatic diseases. The major responses are anti-52 kDa antibodies in primary SS, both anti-52 and anti-60 kDa antibodies in SLE, and anti-60 kDa antibodies in RA and other connective tissue diseases.

Antibodies, Antinuclear↗
PubMed1994

[Clinical and serologic course of patients with mixed connective tissue disease].

The so called mixed connective tissue disease (MCTD), continues to be a controversial entity, while some authors considered it a good characterized disease, others think that is an undifferentiated connective tissue disease. OBJECTIVE. To analyse the clinical and serological evolution of a group of patients diagnosed of MCTD, with particular consideration to the meaning of anti-nRNP and anti-Sm antibodies. METHOD. We have studied 20 patients diagnosed of MCTD and 112 with systemic lupus erythematosus (SLE). Anti-nRNP and anti-Sm antibodies were detected through counter immunoelectrophoresis, immunoblotting and ELISA. RESULTS. After an average time of evolution of 10 years, 70% (14/20) of the patients diagnosed of MCTD fulfill criteria for SLE (6 cases), scleroderma (6 cases) or polymyositis (2 cases). Anti-nRNP response is persistent, directed mainly against the 70 Kd and A-nRNP polypeptides and qualitatively higher in MCTD in SLE (absorbencies 2.64 vs 1.25. The immunoblotting test detected anti-Sm antibodies in 5 patients (25%) and ELISA test in 14 (70%). CONCLUSIONS. Clinical and serological evolution suggest that MCTD is an undifferentiated connective tissue disease. Anti-nRNP antibodies are characteristic, although anti-Sm antibodies can be detected with ELISA regardless whether on not patients fulfill SLE criteria.

Adolescent↗
PubMed1994

[Adult patients with clinically suspected or known biliopancreatic pathology in whom ERCP is not indicated: the 10 most frequent situations].

Endoscopic retrograde cholangiopancreatography is an invasive endoscopic technique widely used in the diagnosis and eventual therapeutic procedures of many biliopancreatic conditions. While endoscopic retrograde cholangiopancreatography indications are well known, it is not the same in those patients with clinically suspected or known biliopancreatic entities in whom endoscopic retrograde cholangio-pancreatography is not indicated because it will not add valuable information with the potential of changing the previous diagnosis or therapy. Ten very common clinical situations in which this technique is not indicated are presented; among them idiopathic abdominal pain, some pancreatic carcinomas, chronic pancreatitis and pancreatic pseudocyst, and some patients awaiting conventional or laparoscopic cholecystectomy. We acknowledge that some aspects of this paper are controversial.

Adult↗
PubMed1987

Rapid automated method for screening of enteric pathogens from stool specimens.

A total of 800 colonies suggestive of Salmonella, Shigella, or Yersinia species isolated on stool differential agar media were inoculated onto both conventional biochemical test media (triple sugar iron agar, urea agar, and phenylalanine agar) and Entero Pathogen Screen cards of the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.). Based on the conventional tests, the AutoMicrobic system method yielded the following results: 587 true-negatives, 185 true-positives, 2 false-negatives, and 26 false-positives (sensitivity, 99%; specificity, 96%). Both true-positive and true-negative results were achieved considerably earlier than false results (P less than 0.001). The Entero Pathogen Screen card method is a fast, easy, and sensitive method for screening for Salmonella, Shigella, or Yersinia species. The impossibility of screening for oxidase-positive pathogens is a minor disadvantage of this method.

Bacteriological Techniques↗
PubMed1985

[Biologic reagents].

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ABO Blood-Group System↗