Biomedical subjects

A Torres

Publications and source records attributed to A Torres.

At least 559 records · Page 31Linked to original sources

PubMed1990

Health maintenance organizations in developing countries: what can we expect?

Health maintenance organizations (HMOs) are a relatively new and alternative means of providing health care, combining a risk-sharing (insurance) function with health service provision. Their potential for lowering costs has attracted great interest in the USA and elsewhere, and has raised questions regarding their applicability to other settings. Little attention, however, has been given to critically reviewing the experience with HMOs in other countries, particularly concerning their introduction to settings other than the USA. This paper first reviews the current experience of HMOs in low- and middle-income countries, including Argentina, Bolivia, Brazil, Colombia, Ecuador, Uruguay, Chile and Indonesia. Secondly, the paper reviews the USA experience with HMOs: prerequisites for the establishment of HMOs in the USA are identified and discussed, followed by a review of the performance of HMOs in terms of cost containment, integration of care and quality of care for the elderly and poor. The analysis concludes that difficulties may arise when implementing HMOs in developing countries, and that potential adverse effects on the overall health care delivery system may occur. These should be avoided by careful analyses of a nation's health care system.

Developing Countries↗

PubMed1990

Monoclonal analysis of fine-needle aspiration biopsy in kidney allografts.

To evaluate changes in T-lymphocyte subsets and DR expression on tubular cells, 74 fine-needle allograft aspirates (FNAB) were evaluated in 31 patients with cadaver kidney transplants. Monoclonal antibodies against T helper CD4+, cytotoxic/suppressor CD8+, and HLA-DR were used with an indirect alkaline-phosphatase-staining technique. Cases with acute rejection (n = 11) showed a significant increase of CD8+: CD4+ ratio versus those with stable function (n = 21), acute tubular necrosis (n = 10) or CsA toxicity (n = 7) (ANOVA F = 10; P less than 0.01). Cases with chronic rejection or CMV infection showed no differences in the CD8+: CD4+ ratio with the other groups. DR expression on tubular cells was frequently found in cases of acute rejection, chronic rejection and CMV (73%, 66%, and 43% respectively), occasionally found in CsA toxicity (14%), but never seen in controls or ATN. Both tests, the CD8+: CD4+ ratio and the DR expression on tubular cells, had a high sensitivity and specificity in differentiating acute rejection versus controls, acute tubular necrosis, and CsA toxicity. When both tests are taken together no case without rejection showed a CD8+:CD4+ ratio greater than 1.6 and DR expression on tubular cells. Cases with acute rejection who lost the graft (n = 6) had a CD8+:CD4+ ratio significantly greater than those who responded to antirejection therapy (n = 5) (t = 2.9; P less than 0.05).

Antibodies, Monoclonal↗

PubMed1990

Relation between the increase of circulating CD3+ CD57+ lymphocytes and T cell dysfunction in recipients of bone marrow transplantation.

Some patients undergoing bone marrow transplantation (BMT) persistently present increased proportions of circulating CD57+ T cells. We analysed the cell surface phenotype in peripheral blood mononuclear cells (PBMC) from 69 allogeneic and 11 autologous BMT recipients. In parallel samples from 49 patients, the proliferative response to T cell mitogens was assessed, either in the presence or absence of exogenous interleukin-2 (IL-2). PBMC samples from long-term allogeneic BMT patients with increased proportions of CD57+ cells displayed significantly (P less than 0.001) lower proliferative responses, compared with samples from patients with normal proportions of CD57+ cells and from healthy subjects. Elimination of the CD57+ population by C'-dependent lysis did not normalize the proliferative response. After positive selection by cell sorting, CD57+ cells responded poorly, but in the presence of IL-2 the proliferation appeared to be similar to that displayed by the CD57- subset and still suboptimal compared with normal controls. These data suggest that the hyporesponsiveness to mitogenic stimuli in the presence of exogenous IL-2 of PBMC from allogeneic BMT recipients cannot be simply attributed either to the putative suppressor activity of CD57+ cells, or to a poor proliferative capacity of this subset. Supporting this notion we report that PBMC from long-term autologous BMT recipients containing high proportions of CD57+ T cells respond normally to T cell mitogens.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1990

Neutralization of low molecular weight heparin by polybrene prevents thromboxane release and severe pulmonary hypertension in awake sheep.

Protamine reversal of heparin anticoagulation in patients is occasionally associated with life-threatening acute pulmonary hypertension. In a sheep model, we evaluated the effect on this adverse cardiopulmonary reaction of modifying the type of heparin (low molecular weight heparin compared with unfractionated heparin) and the type of heparin antagonist (polybrene compared with protamine). Protamine reversal of low molecular weight heparin (LMWH) and polybrene reversal of unfractionated heparin induced more than a 10-fold increase of plasma thromboxane B2 levels, a threefold increase of pulmonary vascular resistance and pulmonary artery pressure, and a 25% decrease of PaO2. A similar adverse reaction followed protamine reversal of conventional unfractionated heparin. However, with polybrene (1 mg/kg) reversal of LMWH (1 mg/kg), we measured neither pulmonary hypertension (pulmonary artery pressure was 22.6 +/- 3.6 mm Hg at 1 minute after polybrene reversal of LMWH compared with 47.9 +/- 4.2 mm Hg after protamine reversal of unfractionated heparin, p less than 0.005 groups differ), hypoxemia (PaO2 was unchanged 2 minutes after polybrene compared with a decrease of 26 mm Hg 2 minutes after protamine, p less than 0.05), nor acute release of thromboxane into arterial plasma (thromboxane B2 was 0.2 +/- 0.1 at 1 minute after polybrene compared with 3.7 +/- 1.7 ng/ml at 1 minute after protamine, p less than 0.005). The hemodynamic effects and mediator release were also benign after neutralization of larger doses of LMWH (3 mg/kg) by polybrene (3 mg/kg). The increases of activated clotting time and activated partial thromboplastin time due to both types of heparin were completely reversed with polybrene. Anti-Xa activity increased to more than 3 IU/ml 4 minutes after LMWH anticoagulation (p less than 0.01) but was only partially neutralized by polybrene. Various polyanion-polycation complexes that are formed when heparin anticoagulation is reversed induce thromboxane release and acute pulmonary vasoconstriction in awake sheep. Reversal of LMWH anticoagulation with polybrene does not elicit this adverse reaction.

Animals↗

PubMed1990

Incidence, risk, and prognosis factors of nosocomial pneumonia in mechanically ventilated patients.

Seventy-eight (24%) episodes of nosocomial pneumonia (NP) were detected in 322 consecutive mechanically ventilated patients admitted to a 1,000-bed teaching hospital from April 1987 through May 1988 to assess the incidence, risk, and prognosis factors of NP acquired during mechanical ventilation (MV). The risk and prognosis factors for developing NP during MV were studied using both univariate and multivariate statistical techniques. Multivariate analysis selected the following variables significantly associated with a higher risk for developing ventilator-associated pneumonia: more than one intubation during MV (p = 0.000012), a prior episode of aspiration of gastric content (p = 0.00018), a MV period longer than 3 days (p = 0.015), the presence of chronic obstructive pulmonary disease (COPD) (p = 0.048), and the use of positive end-expiratory pressure (PEEP) during MV (p = 0.092). The presence of an ultimately or rapidly fatal underlying disease (p = 0.0018), worsening of acute respiratory failure caused by pneumonia (p = 0.0096), the presence of septic shock (p = 0.016), an inappropriate antibiotic treatment (p = 0.02), and the type of intensive care unit (ICU) hospitalization (noncardiac surgery and nonsurgical ICU compared with post-cardiac surgery ICU) (p = 0.08) were those factors selected by a stepwise logistic regression analysis as independently worsening the prognosis. The overall fatality rate was 23% (73 of 322). The mortality of patients with NP was higher (33%; 26 of 78; p less than 0.01) when compared with fatality rates of patients without NP (19%; 47 of 244).(ABSTRACT TRUNCATED AT 250 WORDS)

Cross Infection↗

PubMed1990

Diagnostic value of nonfluoroscopic percutaneous lung needle aspiration in patients with pneumonia.

In forty-one patients (mean [+/- SD] age 51 +/- 19 years; range, 11 to 88 years; seven female and 34 male) with clinical signs and symptoms of pneumonia, we performed a nonfluoroscopic percutaneous lung needle (22 gauges) aspiration (PLNA) to investigate the diagnostic yield of this technique. All the patients were receiving antibiotics at the time of the study, and PLNA was performed either because of a lack of response to empiric antibiotic treatment or because of the severity of the pneumonia or the underlying condition of the patient. Eight patients were mechanically ventilated (MV) due to acute respiratory failure. The PLNA was performed at bedside and without fluoroscopic guidance. Twenty-two microorganisms were identified by means of stains and/or cultures of PLNA samples. Sensitivity of PLNA was 43 percent (18/41). We detected three false-positive cultures probably due to contamination from the skin area punctured. In the eight MV patients studied, the sensitivity of PLNA was 37.5 percent, and the microbiologic findings turned out to be crucial for the outcome of the patients. Pneumothorax developed in three patients (7 percent) after PLNA. None of these three patients developed a pleural infection but two of them required thoracostomy drainage. None of the MV patients presented complications. Our results showed that nonfluoroscopic PLNA is a technique with moderately good sensitivity and with a low rate of false-positive cultures (8 percent) to diagnose pulmonary infections in patients with unresponsiveness to empiric antibiotic treatment or with severe pneumonia. Further evaluation of its diagnostic value and complications in MV patients is needed, although our preliminary results suggest that PLNA can be an alternative technique to other methods for diagnosing pulmonary infections in patients receiving artificial ventilatory support.

Adolescent↗

PubMed1990

[Antibody-coated bacteria and quantitative culture in sputum samples from patients with bronchiectasis].

The results of the quantitative culture of sputum samples from patients with bronchiectasis were compared with those obtained in the same samples with the detection of antibody-coated bacteria (ACB), in the acute phase of the disease (group I), after antibiotic therapy (group II), and in the phase of clinical stability (group III). In quantitative cultures at least one potentially pathogen species was isolated, at a concentration of greater than or equal to 10(6) colony forming units/ml in the 7 sputum samples from group I, in 4 of the 5 samples from group II, and in 10 of the 11 samples from group III. The immunofluorescence technique detected ACB in all samples from group I and group II, and in 10 of the 11 from group III. The sample from group III in which ACB were not detected was the same in which potentially pathogen organisms were not detected by culture.

Acute Disease↗

PubMed1990

[Calculation of the mitral valve area using Hatle's method. Effect of the preload change induced by nitrates].

The aim of the present study was to assess the effect of changes in preload induced by nitrates on calculated mitral valve area by Doppler pressure half-time. Forty patients (mean age 51 +/- 10 years), 23 with mitral stenosis, ten with mechanical prosthesis and seven with bioprosthesis were studied by Doppler echocardiography. Twelve were in sinus rhythm and 28 had atrial fibrillation. Mitral valve area by Doppler pressure half-time, peak and mean mitral gradient and pulmonary artery systolic pressure were measured before and after isosorbide dinitrate (5 mg) or nitroglycerin (0.4 mg). The nitrates produced a significant reduction of pre-load in total group (p less than 0.001) but did not change the mitral valve area (1.9 +/- 0.8 to 1.9 +/- 0.8). The subsets of patients with size valvular area (greater than 2 cm2, less than 2 cm2, less than 1.5 cm2, mechanical prosthesis, bioprosthesis, sinus rhythm and atrial fibrillation) had an insignificant change in mitral valve area after administration of nitrates. We conclude that the mitral valve area by Doppler pressure half-time method do not modify in different conditions of preload. These findings remain in patients with prosthesis, different sizes of mitral valve area and atrial fibrillation.

Adult↗

PubMed1990

Characteristics of patients with soybean dust-induced acute severe asthma requiring mechanical ventilation.

Patients presenting with acute severe asthma during the Barcelona's outbreaks caused by soybean dust inhalation from August, 1981, through September, 1987, characteristically showed an abrupt severe onset of each attack followed by a rapid relief of symptoms after treatment. To throw further light on clinical findings, pathophysiology and outcome in the most life-threatening episodes, we reviewed records of acute severe asthma patients treated by mechanical ventilation in one of the four main hospitals of the city. Twelve such patients (15 episodes) were compared to 24 non-epidemic asthmatic patients (25 episodes) also treated by mechanical ventilation in the same institution during the same period of time. There was a male predominance during outbreaks (p less than 0.03) and epidemic patients were ventilated fewer hours (12 +/- 8 h) (mean +/- SD), admitted fewer days to intensive care (1.6 +/- 0.7 days), and hospitalized fewer days (7.1 +/- 4.4 days) than non-epidemic patients (65 +/- 84 h, 4.6 +/- 3.8 days (p less than 0.001, each), and 16.0 +/- 13.2 days (p less than 0.004), respectively). These differences together with both the fulminant presentation of the episodes of epidemic asthma and the point-source origin of the asthma outbreaks previously shown are consistent with the unusual nature of the aetiologic agent, soybean dust.

Acute Disease↗

PubMed1989

[Familial deficiency of protein S associated with thrombophilia].

Protein S (SP) is a vitamin K-dependent plasma protein which acts as a cofactor of activated C protein in the inactivation of the factors Va and VIIIa; in addition, it enhances fibrinolysis by increasing the affinity of the enzyme for phospholipid surfaces. The congenital deficiency of SP is an autosomal dominant inherited trait, associated with a high risk of development of thrombotic phenomena at a relatively early age (young adults). We report a Spanish family which carried a congenital deficiency of SP associated with thrombotic complications; for its diagnosis we used the immunological quantification of the levels of free and total SP as well as the evaluation of the immunoelectrophoretic behavior of the inhibitor.

Adolescent↗

PubMed1989

Contact phase of blood coagulation in cardiogenic pulmonary oedema (CPO) and adult respiratory distress syndrome (ARDS).

In order to assess the role of the kallikreinkinin (k-k) system in the pathogenesis of pulmonary oedema, we studied the contact phase factors of blood coagulation, as well as the haemodynamics and blood gas changes in 34 patients with pulmonary oedema, 23 of them with Adult Respiratory Distress Syndrome (ARDS) and 11 with cardiogenic pulmonary oedema (CPO). We have verified significant differences in the haemodynamic pattern and blood gases between the two groups of patients, which corroborate the previously established differences between both types of pulmonary oedema. Our results reveal k-k system activation in ARDS patients, with a significant fall in factor XII (p less than 0.05), prekallikrein (p less than 0.01), alpha-2-macroglobulin (p less than 0.01) and high molecular - weight kininogens (p less than 0.005), with a rise in C1-esterase inhibitor (p less than 0.001) in comparison with patients with CPO. All of the CPO patients had normal prekallikrein levels, whereas 15 out 23 ARDS cases (65%) had decreased prekallikrein values. Our results suggest that the k-k system activation could play a role in the pathogenesis of ARDS. Estimation of prekallikrein levels may be helpful in the differential diagnosis of ARDS.

Adult↗

PubMed1989

Cyclosporin A versus methotrexate, followed by rescue with folinic acid as prophylaxis of acute graft-versus-host disease after bone marrow transplantation.

Fifty-seven patients undergoing bone marrow transplantation were randomly assigned to receive either cyclosporin A (CsA, n = 26) or methotrexate, followed by rescue with folinic acid (MTX + FA, n = 31) as prophylaxis for graft-versus-host disease (GVHD). All patients but one receiving CsA had evidence of sustained engraftment, and there was no difference between the two groups on the day in which marrow engraftment was documented. Oropharyngeal mucositis was of similar incidence and severity in the two groups. In contrast, patients receiving CsA showed higher renal and hepatic toxicity rates than those treated with MTX + FA. Severe-to-moderate acute GVHD (grades II-IV) was documented in 12 patients receiving CsA and in 12 treated with MTX + FA. The cumulative incidence of this complication was similar in both groups (46.1% and 38.7%). Similarly, there was no difference in the incidence of chronic GVHD. The leukemic relapse rates were also comparable, as well as the estimated probability of survival, which was 55% in patients treated with MTX + FA and 41% in those who were given CsA. We conclude that MTX + FA is as effective as CsA in the prevention of GVHD, with the additional advantage of reduced renal and hepatic toxicities.

Actuarial Analysis↗

PubMed1989

Incidence and etiology of pneumonia acquired during mechanical ventilation.

A total of 77 consecutive patients submitted to mechanical ventilation (MV) for greater than 48 h in a respiratory ICU (RICU) were studied to investigate the incidence, etiology, and consequences of ventilator-associated pneumonia. Eighteen (23%) patients developed a bacterial pneumonia after 5.6 +/- 1.0 days (mean +/- SEM; range 2 to 17) of MV. Three additional cases were demonstrated at autopsy, raising the incidence to 27%. Overall, the mean duration of MV increased from 9.7 +/- 0.9 to 32.2 +/- 5.1 days (p less than .0001) when pneumonia developed. A longer period of hospital stay before RICU admission and the presence of chronic obstructive pulmonary disease were significant characteristics of patients with pneumonia when compared to patients without nosocomial pulmonary infection. One or more etiological agents were identified in 14 patients from the pneumonia group by means of a highly specific technique (protected brush catheter, transthoracic needle aspiration, pleural fluid, and/or blood cultures). The predominant pathogens isolated were Gram-negative bacilli (Acinetobacter sp. and Pseudomonas sp.). Half of the cases were polymicrobial. Compared to other series, our results may reflect with more accuracy the actual incidence of nosocomial pneumonia in mechanically ventilated patients, since we used highly accurate techniques along with autopsy findings which allowed us to confirm or discard the diagnosis of bacterial pneumonia.

Cross Infection↗

PubMed1989

Alpha-blockade on blood pressure and on cardiac noradrenaline content in SHR and DOCA-salt rats.

The current study was designed to explore the effects of peripherally administered alpha-adrenoceptor inhibiting drugs (either prazosin or yohimbine) in spontaneously hypertensive (SHR) and DOCA-salt hypertensive rats before the development of established hypertension, as well as to characterize changes induced by prazosin and/or yohimbine in the cardiac noradrenaline (NA) content that might be responsible for the development of hypertension in these strains. The alpha-adrenoceptor blockade can prevent hypertension in DOCA and salt-treated animals in such a way that their blood pressure stabilizes at levels significantly lower than those observed in similarly treated normotensive controls. Significantly lower cardiac NA content was observed in DOCA-salt rats under basal and experimental conditions. The blood pressure of the treated rats and the heart NA content of the SHR were unaltered by treatment. Thus, administration of the alpha-adrenoceptor blocking agents, prazosin and/or yohimbine, throughout the developmental stage of SHR hypertension failed to alter either the progressive rise in blood pressure or in NA content. There may be differences between the cardiac adrenergic mechanisms responsible for the development of hypertension in each of these two models of hypertension.

Adrenergic alpha-Antagonists↗

PubMed1989

Bronchoalveolar lavage cell analysis in patients with human immunodeficiency virus related diseases.

The value of differential cell counts in bronchoalveolar lavage fluid in patients who were serologically positive for the human immunodeficiency virus (HIV) was studied in 30 patients with classified into four groups according to the severity of illness: (1) seven subjects with the AIDS related complex without clinical or radiological evidence of pulmonary infection; (2) eight patients with the AIDS related complex and pulmonary tuberculosis; (3) eight patients with AIDS and Pneumocystis carinii pneumonia; and (4) seven patients with AIDS, Pneumocystis carinii pneumonia, and severe respiratory failure. All four groups had a similar percentage of lymphocytes, significantly higher than that of a control group of 15 healthy volunteers. A significant increase in the percentage of neutrophils was observed in groups 2, 3, and 4. The lavage fluid differential cell count does not therefore appear to help in the differential diagnosis of pulmonary infections in HIV positive patients. The abnormal percentage of lymphocytes observed in some patients with the AIDS related complex without clinical evidence of pulmonary infection suggests that lung injury may exist before clinical or radiological abnormalities develop. This might be related to an immunological mechanism or might be caused by an undetected subclinical infection.

AIDS-Related Complex↗

PubMed1989

Effect of platelet depletion on lung vasoconstriction in heparin-protamine reactions.

In six awake sheep the control heparin-protamine reaction was associated with a 150-fold rise in arterial plasma thromboxane B2 (TxB2) levels, a 4.5-fold increase in pulmonary vascular resistance, a 20% decrease in cardiac output, a 30% decrease in arterial PO2, and a 30% reduction in arterial white blood cell concentrations. Depletion of 99% of circulating platelets by antibodies did not prevent either acute and severe pulmonary hypertension or increased plasma TxB2 levels induced by heparin-protamine administration. We produced sheep platelet aggregation in vitro with bovine thrombin and measured marked TxB2 release (36.3 +/- 16.3 ng/10(9) platelets). In contrast, neither heparin, protamine, nor heparin-protamine complexes over a 10,000-fold range of concentrations induced platelet aggregation and release of thromboxane in vitro. Therefore sheep platelets are not the source of thromboxane production associated with acute pulmonary hypertension during the heparin-protamine reaction, and other cells must produce the thromboxane.

Animals↗

PubMed1989

Sonomicrometric regional diaphragmatic shortening in awake sheep after thoracic surgery.

Through a right thoracotomy in seven sheep we chronically implanted sonomicrometry crystals and electromyographic electrodes in the costal and crural diaphragmatic regions. Awake sheep were studied during recovery for 4-6 wk, both during quiet breathing (QB) and during CO2 rebreathing. Tidal volume, respiratory frequency, and esophageal and gastric pressures were studied before and after surgery. Normalized resting length (LFRC) was significantly decreased for the costal segment on postoperative day 1 compared with postoperative day 28. Fractional costal shortening both during QB and at 10% end-tidal CO2 (ETCO2) increased significantly from postoperative days 1 to 28, whereas crural shortening did not change during QB but progressively increased at 10% ETCO2. Maximal costal shortening during electrophrenic stimulation was constant at 40% LFRC during recovery, although maximal crural shortening increased from 23 to 32% LFRC. Minute ventilation, tidal volume, and transdiaphragmatic pressure at 10% ETCO2 increased progressively after thoracotomy until postoperative day 28. Our results suggest there is profound diaphragmatic inhibition after thoracotomy and crystal implantation in sheep that requires at least 3-4 wk for stable recovery.

Animals↗

PubMed1989

Therapeutic efficacy of the combination of aztreonam with cefotaxime in the treatment of severe nosocomial pneumonia. Comparative study against amikacin combined with cefotaxime.

The combination aztreonam + cefotaxime (AZ + CE) was compared to amikacin + cefotaxime (AM + CE) in the treatment of nosocomial pneumonia acquired at the intensive-care unit. This study included a total of 33 patients fulfilling criteria for nosocomial pneumonia. 16 of them were randomly allocated to the AZ + CE group and 17 to the AM + CE group. The empirical treatment was effective for 78% of AZ + CE cases and 92% of AM + CE cases (p = NS). Clinical care was observed in 77% of cases (10 out of 13 evaluable) in the AZ group and in 75% of the group treated with AM (12 cases out of 16 evaluable; p = NS). In the evaluable cases, treatment failure was associated with injections due to the following organisms: Acinetobacter calcoaceticus (1) and Pseudomonas aeruginosa (1) in the AZ group and A. calcoaceticus (1) in the AM group. Superinfections were observed only in the AM group P. aeruginosa. A. calcoaceticus, Streptococcus viridans, Candida albicans, Aspergillus fumigatus and Serratia marcescens. Both the peak and through serum concentrations of AZ and AM were maintained within normal ranges. Finally, an impairment of renal tubular function was observed in the group of patients treated with AM, as measured by urinary levels of N-acetyl-beta-D-glucosaminidase and leucine aminopeptidase sequentially during the treatment. These changes in renal functions alterations mentioned were not observed in the AZ group. It is concluded that the AZ + CE combination is an effective empirical and active antibiotic treatment against severe nosocomial pneumonia. Aztreonam has no renal toxicity, which is an advantage to take into account in patients with altered renal function.

Adult↗