Search PubMed⌕ Search

Biomedical subjects

A Torres

Publications and source records attributed to A Torres.

At least 397 records · Page 22Linked to original sources
PubMed1996

Influence of vitamin D receptor genotype on bone mass changes after renal transplantation.

Renal transplant patients immunosuppressed with cyclosporine A (CsA) exhibit both a significant bone loss and an increased rate of bone fractures. An association between common allelic variants of the the vitamin D receptor (VDR) gene and bone mineral density and turnover has been reported in adults. However, the genetic influence on the rate of bone loss after renal transplantation has not been explored. We prospectively determined the changes in spinal mineral density in 34 consecutive nondiabetic adults who received a cadaveric renal allograft. Serum biochemical markers of bone metabolism and the vertebral mineral density (VMD) assessed by quantitative computed tomography were determined at the time of transplantation and three and twelve months later. In fifteen patients the histomorphometric features of iliac bone were analyzed at baseline and twelve months after transplantation. VDR alleles were typed by a PCR assay based on a polymorphic BsmI restriction site. Patients with the so-called "favorable" bb genotype (N = 12) were compared with those with the Bb or BB genotype (N = 22). Baseline VMD was similar in patients with or without the favorable bb genotype. Three months after transplantation the mean (+/- SD) VMD decreased 14 +/- 13.3 percent in all patients (16.5 +/- 13.1% in patients homozygous for the b allele and 13.77 +/- 13.9% in those with Bb or BB genotypes). The rate of VMD loss at this time inversely correlated with pretransplant PTH levels (r = -0.40; P < 0.05). Between 3 and 12 months after transplantation, patients with the favorable bb genotype recovered more VMD than those with Bb or BB types and showed a significantly higher Z score at the end of the follow-up (-0.37 +/- 1.16 vs. -1.10 +/- 1.20, respectively; P < 0.05). The beneficial effect of bb genotype was independent of the prevailing PTH levels and was also observed in those patients with a baseline PTH level < 250 pg/ml (final Z score: bb, -0.42 +/- 1.3, N = 11; Bb/BB, -1.35 +/- 0.8, N = 11, P < 0.05). At the end of follow-up, the histomorphometric studies showed a higher bone formation rate adjusted for PTH levels in patients with the Bb or BB genotype than in those with the favorable bb genotype (0.29 +/- 0.06 vs. 0.21 +/- 0.08 micron3/micron2/day respectively; P < 0.05). In conclusion, high pretransplant PTH levels enhance the early trabecular bone loss after renal transplantation, and functionally different alleles of the vitamin D receptor gene may condition the bone turnover and the degree of recovery of the bone mass.

Adult↗
PubMed1996

High phosphorus diet increases preproPTH mRNA independent of calcium and calcitriol in normal rats.

Phosphorus retention favors secondary hyperparathyroidism by decreasing calcitriol synthesis and serum calcium levels. However, a direct effect of high extracellular phosphorus on parathyroid (PTH) function, gene expression, and cell proliferation is still controversial. Normal rats were fed standard (St; 0.6% calcium, 0.6% phosphorus) or high phosphate (HP) diet (0.6% calcium, 1.2% phosphorus) for 18 days. To rule out transient decreases in serum calcium or calcitriol levels, sets of animals were sacrificed at different time periods after the last feeding (2, 4, 8, 12 or 24 hr). The HP diet led to hyperphosphatemia and secondary hyperparathyroidism and maximum differences in PTH levels were observed eight hours after feeding (St 29.4 +/- 15 vs. HP 87.9 +/- 56 pg/ml, mean +/- SD; P = 0.01). High levels induced by the HP diet prevented both hypocalcemia and low calcitriol levels at each study point. The HP diet also promoted a significant increase of PTH mRNA levels that peaked about eight hours after feeding (100% increase). This was confirmed at the cellular level by in situ hybridization. Parathyroid glands from animals fed the HP diet showed a 25% increase in volume with respect to the St diet (P = 0.01), and a typical pattern of hyperplasia was found. Parathyroid vitamin D receptor (VDR) mRNA levels were not modified by the HP diet. In conclusion, parathyroid gene expression per cell and parathyroid cell hyperplasia are stimulated by high dietary phosphorus independently of calcium and calcitriol. This effect is not mediated by alterations in the gene expression of the parathyroid calcitriol receptor. Our findings emphasize the importance of the control of hyperphosphatemia in chronic renal failure patients.

Animals↗
PubMed1996

Parathyroid gland calcium receptor gene expression is not regulated by increased dietary phosphorus in normal and renal failure rats.

The extracellular calcium regulation of parathyroid hormone (PTH) secretion is mediated by a cell surface G-protein-coupled calcium receptor (PCaR). The abnormal calcium sensing in renal failure could be the result of abnormalities of the PCaR. However, PCaR gene expression has been shown to be unaffected by 5/6 nephrectomy in the rat. Whether factors that enhance secondary hyperparathyroidism in renal failure affect the PCaR gene expression is not known. We studied normal rats (sham) (n = 40) and renal failure rats (3/4 nephrectomy) (n = 40). Half of the rats in each group received standard (0.6% calcium, 0.6% phosphorus) and half high phosphorus (0.6% calcium, 1.2% phosphorus) diet. Compared to the standard diet, the high phosphorus diet induced secondary hyperparathyroidism both in sham and in renal failure rats (intact PTH: 22.3 +/- 2.03 vs 54.3 +/- 7.6, P < 0.01, and 26.2 +/- 3.9 vs 178.7 +/- 23.2 pg/ml, P < 0.01, respectively). After the cloning of a rat PCaR cDNA fragment corresponding to the extracellular domain which showed an 89% homology with its bovine counterpart, a probe for Northern blot analysis was obtained. No differences in the PCaR mRNA/18s RNA ratio in high phosphorus compared to the standard diet group were observed, both in sham and in renal failure rats. In conclusion, PCaR gene expression is not involved in the genesis of the secondary hyperparathyroidism induced by a high phosphorus diet. An alternative means of increasing PTH secretion by phosphorus loading could be an alteration of the sensitivity of the PCaR to activation by extracellular calcium.

Amino Acid Sequence↗
PubMed1996

Histopathologic and microbiologic aspects of ventilator-associated pneumonia.

BACKGROUND: The relationship between microbiology and histology in patients with ventilator-associated pneumonia has been sparsely described. METHODS: Twenty-five patients who died in the intensive care unit after their lungs had been mechanically ventilated for 72 h were studied. Twenty of the 25 died with clinical suspicion of pulmonary infection. A total of 375 immediate postmortem pulmonary biopsies were obtained after death and processed for quantitative microbiology and histology. Four evolutionary stages of pneumonia were defined: early, intermediate, advanced, and resolution. RESULTS: At least one specimen with histologic evidence of pneumonia was found in all but two patients (92%). Histologic pneumonia was a widespread and frequent process (46%) of biopsies examined) involving predominantly the lower lobes (55% of all biopsies with pneumonia) and showing different histopathologic stages of progression coexisting in the same lung lobes. Lung cultures were frequently polymicrobial (149 of 375, 40% of the pulmonary biopsy cultures, and 20 of 25, 80% of the cases) and not always yielding the same pathogen (19 microorganisms) when comparing one lung to the other. Histopathology and microbiologic biopsy cultures showed a weak relationship (28% and 49% of species had counts > or = 10(3) cfu/g in samples without pneumonia from patients with and without prior antibiotic treatment, respectively). Histopathologic evolutionary stages were not associated with any differences in quantitative culture results of pulmonary biopsies, independently of prior administration of antibiotics. Higher bacterial concentrations of biopsy cultures were associated with the absence of prior antibiotic treatment. CONCLUSIONS: Ventilator-associated pneumonia is a frequent diffuse and polymicrobial process showing different coexisting degrees of evolution and involving preferentially the lower lobes. Microbiology and histology can be dissociated even in the absence of prior antibiotic treatment. Lung histology appears more reliable than bacteriology as a diagnostic reference test.

Adult↗
PubMed1996

Effect of phosphate on the parathyroid gland: direct and indirect?

Hyperparathyroidism is a common finding in patients with renal failure. Phosphorus retention is known to be an important factor in the development of secondary hyperparathyroidism. Exciting new work has demonstrated that a high extracellular phosphorus concentration directly stimulates parathyroid hormone secretion and synthesis. Dietary phosphorus also modulates parathyroid function indirectly by decreasing calcitriol production, and it interferes with the calcaemic response to parathyroid hormone. The information available suggests that the control exerted by phosphorus is critical, via indirect and direct actions, in preventing the development of secondary hyperparathyroidism.

Animals↗
PubMed1996

Aortic thrombosis in a neonate with hereditary antithrombin III deficiency: successful outcome with thrombolytic and replacement treatment.

We report the case of a newborn male who presented an aortic thrombosis during the neonatal period and was subsequently diagnosed as having antithrombin III (AT III) hereditary deficiency type I. This hypercoagulable condition is known to predispose young adults to venous thrombosis, but in our patient the primary thrombotic incident affected the arterial vessels within the first few days of life. Combined treatment with thrombolytic agents and AT III concentrates recovered aortic permeability, suggesting that the use of AT III may be beneficial for the treatment of thrombotic complications during the first few days of life.

Angiography, Digital Subtraction↗
PubMed1996

Screening of microorganisms for biodegradation of poly(lactic-acid) and lactic acid-containing polymers.

The ability of some microorganisms to use lactic acid stereocopolymers and copolymers with glycolic acid as sole carbon and energy sources was studied under controlled or natural conditions. First, 14 filamentous fungal strains were tested in liquid cultures, adopting total lactic acid consumption, nitrogen source exhaustion, and maximal biomass production as selection criteria. Two strains of Fusarium moniliforme and one strain of Penicillium roqueforti were able to totally assimilate DL-lactic acid, partially soluble racemic oligomers (MW = 1,000), and the nitrogen source. Only one strain of F. moniliforme was able to grow on a poly(lactic acid)-glycolic acid copolymer (MW = 150,000) after 2 months of incubation at 28 degrees C on synthetic agar medium. Mycelium development was examined by scanning electron microscopy. F. moniliforme filaments were observed to grow not only at the copolymer surface but also through the bulk of the copolymer. In a second approach, plates made of a racemic poly(lactic acid) were buried in the soil before being incubated in petri dishes containing mineral agar medium under controlled conditions. Five strains of different filamentous fungi were isolated, and their ability to assimilate racemic poly(lactic acid) oligomers was tested in liquid cultures.

Biodegradation, Environmental↗
PubMed1996

Value of intracellular bacteria detection in the diagnosis of ventilator associated pneumonia.

BACKGROUND: Markers of ventilator associated pneumonia are of interest for confirming the diagnosis and for guiding the initial management of this frequent complication of mechanical ventilation. The detection of intracellular organisms in the polymorphonuclear leucocytes (PMNLs) and/or macrophages of bronchoalveolar lavage (BAL) fluid has been suggested as a specific test for the early indication of an infectious pulmonary process. METHODS: The diagnostic value of detecting intracellular organisms in two types of BAL fluid--protected (P-BAL) and conventional (C-BAL)--in 25 patients who died in one unit was prospectively studied. Immediately after death both P-BAL and C-BAL were performed bilaterally. Through a minithoracotomy on both sides of the chest bilateral bronchoscopically guided open lung biopsy samples were obtained from the same area, and an average of eight open lung blind biopsy samples (not bronchoscopically guided) were taken from each lung for histological examination. BAL fluid was examined for quantitative cultures (threshold 10(4) cfu/ml) and for the presence of intracellular organisms and extracellular organisms, and differential cell counts were also performed. RESULTS: Using the histopathology of the bronchoscopically guided open lung biopsies as the gold standard, detection of intracellular organisms in P-BAL (> or = 5%) and C-BAL (> or = 5%) fluids yielded 75% and 57% positive predictive values, and 83% negative predictive values, respectively. Prior treatment with antibiotics decreased the positive and negative predictive values of intracellular organism detection for both types of BAL fluid. The presence of intracellular organisms was correlated with the quantitative cultures of P-BAL and C-BAL samples. Quantitative cultures from P-BAL fluid were less sensitive (22% versus 45%) and more specific (100% versus 55%) than those from C-BAL samples. The percentage of extracellular organisms and the differential cell count in P-BAL and C-BAL samples could not discriminate between the presence or absence of pneumonia. CONCLUSIONS: The presence of > or = 5% intracellular organisms infecting PMNLs or macrophages in P-BAL or C-BAL fluids is a specific marker of ventilator associated pneumonia.

Bronchoalveolar Lavage Fluid↗
PubMed1996

Renal infarction in a severely hypertensive patient with lupus erythematosus and antiphospholipid antibodies.

Systemic lupus erythematosus (SLE) patients, specially those with antiphospholipid antibodies, have a high incidence of arterial and venous thrombotic manifestations. However, renal infarction has been rarely reported in these patients. The case of a young female with renal infarction, diagnosed by renal arteriography and scintigraphy, and arterial hypertension (AH) is described. In subsequent years she also suffered several cerebrovascular accidents with important neurological sequelae. No evidence of systemic disease was observed at this time. Fourteen years after the renal infarction a diagnosis of SLE was established. Despite therapy with prednisone, acetylsalicylic acid, azathioprine and antihypertensive drugs the progression of the neurological disease led to death. The sudden appearance of severe AH in a young woman with a renal infarction should alert the clinician about a possible underlying renal artery thrombosis in association with SLE and antiphospholipid antibodies.

Adult↗
PubMed1996

Monounsaturated fatty acid-enriched diet decreases plasma plasminogen activator inhibitor type 1.

An increase in levels of plasma plasminogen activator inhibitor type 1 (PAI-1) is one of the main hemostatic alterations in patients with coronary heart disease. Despite growing interest in the fibrinolytic system, few studies have been undertaken to determine the effect exerted on it by the different dietary fatty acids. We investigated the effect of a monounsaturated fat (MUFA)-rich diet in comparison with a low-fat diet (National Cholesterol Education Program step 1 diet) (NCEP-1) on factors involved in blood coagulation and fibrinolysis. We also determined the effect of dietary cholesterol on these blood parameters. Twenty-one young, male, healthy volunteers followed two low-fat/high-carbohydrate diets (< 30% fat, < 10% saturated fat, 14% MUFA) for 24 days each, with 115 or 280 mg of cholesterol per 1000 kcal per day, and two oleic acid-enriched diets (38% fat, 24% MUFA) with the same dietary cholesterol as the low-fat/high-carbohydrate diets. Plasma levels of fibrinogen, thrombin-antithrombin complexes, prothrombin fragments 1+2, plasminogen, alpha 2 antiplasmin, and tissue plasminogen activator were not significantly different among the experimental diets used in this study. Consumption of the diet rich in MUFA resulted in a significant decrease in both PAI-1 plasma activity (P < .005) and antigenic PAI-1 (P < .04) compared with the carbohydrate-rich diet (NCEP-1). The addition of dietary cholesterol to each of these diets did not result in any significant additional effect. Changes in insulin levels and PAI-1 activity were positively correlated (r = .425; P < .02). In conclusion, consumption of diets rich in MUFAs decreases PAI-1 plasma activity, which is accompanied by a parallel decrease in plasma insulin levels.

Adult↗
PubMed1996

Community-acquired pneumonia in the elderly: A multivariate analysis of risk and prognostic factors.

To assess the risk and prognostic factors of community-acquired pneumonia occurring in the elderly (over age 65 yr) requiring hospitalization, two studies, case-control and cohort, were performed over an 8-mo period in a 1,000-bed university teaching hospital. We studied 101 patients with pneumonia (cases), age 78.5 +/- 7.9 yr (mean +/- SD). Each case was matched for sex, age (+/- 5 yr), and date of admission (+/- 2 d) with a control subject, without pneumonia during the preceding 3 yr, arriving at the emergency room. Etiologic diagnosis was obtained in 43 of 101 (42%) cases. The main microbial agents causing pneumonia were: Streptococcus pneumoniae (19 of 43, 44%), and Chlamydia pneumoniae (9 of 43, 21%). Gram-negative bacilli were uncommon (2 of 43, 5%). The multivariate analysis demonstrated that large-volume aspiration, and low serum albumin (< 30 mg/dl) were independent risk factors associated with the development of pneumonia. Crude mortality rate was 26% (26 of 101), while pneumonia-related mortality was 20% (20 of 101). The attributable mortality was 23% (odds ratio [OR]: 11.3; 95% confidence interval [CI]: 3.25 to 60.23; p < 0.0001). The multivariate analysis showed that patients had a worse prognosis if they were previously bedridden, had prior swallowing disorders, body temperature on admission was less than 37 degrees C, respiratory frequency was greater than 30/min or had three or more affected lobes on chest radiograph. Age by itself was not a significant factor related to prognosis. Among the significant risk factors, only nutritional status is probably amenable to medical intervention. The prognostic factors found in this study may help to identify, upon admission, those subjects at higher risk and who may require special observation.

Aged↗
PubMed1996

Community-acquired pneumonia in chronic obstructive pulmonary disease: a Spanish multicenter study.

Community-acquired pneumonia (CAP) is an infectious illness that frequently motivates hospital admission when comorbid conditions are present. However, the epidemiology of CAP in relation to the underlying disease of the patients is not well known. We performed a prospective multicenter study with the aim of assessing the clinical characteristics, etiology, and outcome of chronic obstructive pulmonary disease (COPD) patients with CAP. Between October 1992 and December 1994 we studied 124 COPD patients (mean FEV1 40 +/- 11% of predicted, mean FVC/FEV1 49 +/- 10) admitted because of CAP to one of the participating centers. An attempt to obtain an etiologic diagnosis was performed by means of blood cultures (n = 123), sputum cultures (n = 97), pleural fluid cultures (n = 17), protected specimen brush samples (n = 41), percutaneous transthoracic needle aspiration (n = 41), and serology (n = 106). Etiologic diagnosis was achieved in 80 (64%) of cases, however, diagnosis based upon valid techniques was only possible in 73 (59%) cases. The main causal microorganisms were the following: Streptococcus pneumoniae in 32 (43%), Chlamydia pneumoniae in 9 (12%), Hemophilus influenzae in 7 (9%), Legionella pneumophila in 7 (9%), Streptococcus viridans in 3 (4%), Coxiella burnetii in 3 (4%), Mycoplasma pneumoniae in 2 (3%), Nocordia asteroides 2, Aspergillus ssp. 1, and others 10. In three of these cases the etiology was polymicrobial. Bacteremia was present in 19 (15%) cases; S. pneumoniae was the most frequent isolate (13 cases). Antibiotic treatment was modified in 22 cases due to etiologic findings, and in 9 due to therapeutic failure. Ten patients died (8%), and 22 needed mechanical ventilation, the mortality rate in the latter population being 23%. Total or partial resistance of S. pneumoniae to penicillin was observed in 10 of 32 (31%) isolations, and to erythromycin in 2 (6%). The results of this study are important for the standardization of empiric antibiotic strategies in COPD patients with pneumonia.

Aged↗
PubMed1996

Stomach as a source of colonization of the respiratory tract during mechanical ventilation: association with ventilator-associated pneumonia.

The aetiopathogenesis of ventilator-associated pneumonia (VAP) requires abnormal oropharyngeal and gastric colonization and the further aspiration of their contents to the lower airways. VAP develops easily if aspiration or inoculation of microorganisms occur in patients with artificial airways, in whom mechanical, cellular and/or humoral defences are altered. Well-known risk factors for gastric colonization include: alterations in gastric juice secretion; alkalinization of gastric contents; administration of enteral nutrition; and the presence of bilirubin. However, the role of the colonized gastric reservoir in the development of VAP remains debatable. Evidence in favour of the role of the stomach in the development of VAP comes mainly from randomized, controlled trials of selective gut decontamination and stress ulcer prophylaxis in the intensive care unit (ICU), in which reducing the bacterial burden of the stomach decreases the incidence of nosocomial respiratory infections. However, at least three studies of flora have found an absence of stomach origin of pneumonia occurring during mechanical ventilation. Prophylactic measures suggested to prevent VAP in relation to the gastric reservoir include: treatment for stress ulcers with sucralfate; prevention of duodenal reflux with metoclopramide; reduction of gastric burden and bacterial translocation by selective digestive decontamination; acidification of enteral feeding; and jejunal feeding. Gastro-oesophageal reflux can be prevented by using small bore nasogastric tubes and jejunal feeding. The aspiration of gastric contents can be reduced by positioning patients in a semirecumbent position, checking the patency of the tube cuff, and aspiration of subglottic secretions. The role of the stomach as a reservoir for microorganisms causing ventilator-associated pneumonia is still controversial but despite the debate, there is major evidence in the literature in favour of the gastric origin of part of these pulmonary infections.

Colony Count, Microbial↗
PubMed1996

Bacterial colonization as a potential source of nosocomial respiratory infections in two types of spirometer.

The potential risk of spirometers in the transmission of respiratory infections has not been yet established. We performed a prospective cross-sectional study to determine the rate of colonization of a water-sealed spirometer and a pneumotachograph, and the potential risk of cross-transmission of microorganisms to patients using each of these devices. Fifty four patients (aged 51 +/- 18 (mean +/- SD) yrs) were included in the study. All of them had undergone forced spirometry with bronchodilator response by means of the water-sealed spirometer (n = 36) or the pneumotachograph (n = 18). None had a clinically apparent respiratory infection at the time of the study. Routine hygiene measures for respiratory equipment were performed before the study protocol. Samples for microbiological cultures of different parts both of the water-sealed spirometer (proximal and distal tubing, bell and water-bell) and pneumotachograph (proximal and distal tubing) were taken daily before and after the usual series of lung function tests during a 5 day period. Pharyngeal swab cultures were obtained before spirometry and 7 days later in each subject. Thirty six out of a total of 40 (90%) culture samples from the water-sealed spirometer showed microbial growth compared to 4 out of 30 (13%) samples obtained from the pneumotachograph (p < 0.0001). Significant colonization of the water-sealed spirometer was apparent after the third day of the study. The microorganisms most frequently isolated were penicillium sp. (62%), Pseudomonas fluorescens (32%), and Burkholderia cepacea (48%). Distal tubing, water and water-bell were the parts of the water-sealed spirometer that showed higher colonization counts (> or = 10(4) colony-forming units (cfu).mL-1). No transmission sequence of potentially pathogenic microorganisms from equipment to patients or vice versa could be demonstrated. In summary, the water-sealed spirometer frequently became colonized by microorganisms. The potential hazard of such equipment as reservoirs of microorganisms suggests a need for the implementation of new hygiene measures for their maintenance.

Bacterial Infections↗
PubMed1996

HLA-DR class II and ICAM-1 expression on tubular cells taken by fine-needle aspiration biopsy in renal allograft dysfunction.

BACKGROUND: Percutaneous biopsy is the method of choice for differential diagnosis of renal allograft dysfunction, although it is not risk-free. The use of less aggressive methods for diagnosis should limit the need for percutaneous biopsy to some specific situations. METHODS: We analysed 42 fine-needle aspiration biopsies from 36 kidney allograft recipients immunosuppressed with quadruple sequential therapy who suffered renal allograft dysfunction. Seven cases with stable renal function were used as controls and included as non-rejection cases in the analysis. In all aspirates the Corrected Increment was calculated and an immunocytochemical analysis of renal tubular cells with the monoclonal antibodies HLA-DR and ICAM-1 was performed. RESULTS: The Corrected Increment was increased in 13 out of 18 acute rejection cases and in one out of 31 non-rejection cases. HLA-DR expression was found in more than 30% of tubular cells from the aspirates in 16 out of 18 acute rejection cases and in eight out of 31 cases without rejection (P < 0.001). ICAM-1 expression was detected in more than 30% of tubular cells in 14 out of 18 cases with acute rejection, and in four out of 31 cases without acute rejection (P < 0.001). Interestingly, all acute vascular rejection cases (n = 6), and six out of 12 acute cellular rejection cases expressed both, HLA-DR and ICAM-1, in more than 30% of tubular cells. On the other hand, none of the non-rejection allograft dysfunctions or control samples showed more than 30% of tubular cells immunostained with both HLA-DR and ICAM-1 antibodies. CONCLUSIONS: The immunocytochemical analysis of HLA-DR and ICAM-1 on renal tubular cells taken by fine-needle aspiration biopsy, allows the diagnosis of acute cellular rejection and acute vascular rejection even when the Corrected Increment is not increased. Moreover, the risk of a core renal biopsy can be avoided when both tests are negative since an acute rejection is a remote possibility.

Acute Disease↗