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Biomedical subjects

A Mas

Publications and source records attributed to A Mas.

At least 73 records · Page 4Linked to original sources
PubMed1998

Effect of ranitidine on gastric intramucosal pH in critically ill patients.

OBJECTIVE: To determine whether ranitidine a) increases the values of gastric intramucosal pH (pHi) in critically ill patients, as determined by tonometry; b) reduces the variability of these measurements. DESIGN: Prospective, double blind, randomized, placebo-controlled study. SETTING: General Intensive Care Unit of a teaching hospital. PATIENTS: Twenty-five critically ill, mechanically ventilated patients requiring arterial catheter and nasogastric tube. INTERVENTIONS: Tonometer placement; blind, random administration of intravenous ranitidine (50 mg) or placebo. MEASUREMENTS AND MAIN RESULTS: Tonometer saline PCO2 (PCO2i), arterial blood gases, gastric juice pH and pHi were determined immediately before, and 2, 4, 6 and 8 h after, ranitidine (12 patients) or placebo (13 patients). Ranitidine significantly increased gastric juice pH, but did not affect PCO2i or pHi; pHi was 7.34 +/- 0.14 before ranitidine, and 7.30 +/- 0.12, 7.31 +/- 0.11, 7.31 +/- 0.14 and 7.31 +/- 0.12-2, 4, 6 and 8 h, respectively, after ranitidine administration (p = 0.55). Ranitidine did not modify the coefficients of variation of PCO2i or pHi, either. No significant changes in gastric juice pH, PCO2i or pHi were observed in the placebo group. CONCLUSIONS: In critically ill patients, ranitidine has no effect on pHi values, and does not increase the reproducibility of pHi measurements.

APACHE↗
PubMed1998

Recurrent hydrochlorothiazide-induced pulmonary edema.

Hydrochlorothiazide-induced pulmonary edema is an unusual but life-threatening adverse reaction. It causes hypoxemia, hypotension, tachycardia, fever, and occasionally electrocardiographic and echocardiographic abnormalities. The mechanism of production is, probably, idiosyncratic.

Aged↗
PubMed1998

The decline in CD4+ T lymphocytes as a function of the duration of HIV infection, age at seroconversion, and viral load.

BACKGROUND: The rate of CD4+ T-lymphocyte decline seen in HIV-infected patients is very variable. Although older patients, a longer duration of HIV infection, and a high level of plasma viraemia, have been associated with a faster fall in CD4+ T-cells, the relationship between these variables is still not well known. PATIENTS AND METHODS: In a cross-sectional study that included a total of 107 patients of known age and date at HIV seroconversion, the current CD4+ T-cell count and plasma viraemia were examined. Patients were not taking antiretroviral drugs, nor had received immunizations nor were suffering any intercurrent infections at the time of the study. RESULTS: The mean duration of HIV infection was 8.6+/-2.9 years. The mean CD4+ T-lymphocyte count was 367+/-264 x 10(6)/l. Mean plasma viraemia was 4.3+/-0.9 logs. In a linear regression model, the current CD4+ T-cell count was explained in 21.7% by the duration of HIV infection, while the level of plasma viraemia justified separately up to 37.0%. When both parameters were combined, they explained 58.8%. of the CD4+ lymphocyte values. In this model, a variation of one logarithm in the plasma viraemia had six times greater effect on the number of CD4+ lymphocytes than each year of HIV infection. When the age at seroconversion was added to the model, the CD4+ cell count allowed the explanation of up to 62.2% of cases. CONCLUSIONS: The age at seroconversion, the duration of HIV infection, and the level of plasma viraemia independently and substantially influence the current CD4+ lymphocyte count in HIV-infected subjects. However, other variables should exist (e.g. virus syncytium-inducing phenotype, host immunogenetic repertoire, etc.), contributing to explaining the different rate of CD4+ T-cell decline seen in HIV-infected subjects.

Adult↗
PubMed1998

LTR and tat variability of HIV-1 isolates from patients with divergent rates of disease progression.

The genetic heterogeneity and transcription activity of the human immunodeficiency virus type 1 (HIV-1) LTR region and tat gene have been examined. Comparison involved the relevant genomic regions of viruses isolated from twenty long-term survivors and from ten typical progressors. No significant differences were observed in mutation frequencies among the two groups, although there was a significant higher proportion of synonymous substitutions in the tat gene of viruses from typical progressors. Four LTR sequences showed an insertion of 20-31 residues at the junction between the LTR Nef-coding and the LTR noncoding region. Neither these insertions nor other genetic changes found in these sequences affected the LTR transcription function, as measured in transient expression assays using transfection of both established cell lines and peripheral blood lymphocytes with plasmid DNA. The results did not allow the association of structural or functional alterations in LTR or tat with a degree of disease progression. The results reinforce the concepts of complexity of HIV-1 evolution in infected individuals, and the multifactorial nature of progression to AIDS.

Adult↗
PubMed1998

Ecstasy: a common cause of severe acute hepatotoxicity.

BACKGROUND/AIMS: Ecstasy is a synthetic amphetamine recently identified as a possible cause of acute liver injury. This drug is consumed by young people and has a marked effect on improving sociability. The extent of ecstasy-associated severe hepatic damage is unknown to date. METHODS: The clinical histories of 62 patients with acute liver failure admitted to the Intensive Care Liver Unit between January 1994 and December 1996 were reviewed to assess the frequency, the epidemiological, clinical and histological characteristics and the outcome of ecstasy-induced severe hepatitis. RESULTS: Over this period of time, five patients (8%) were admitted because of ecstasy-induced acute liver failure, representing 31% of the cases with drug hepatotoxicity. Ecstasy was the second most common cause of liver injury in patients under the age of 25 years, being 20% in this subset of patients and 36% after ruling out the cases of viral etiology. All the patients had severe liver disease of acute onset, with jaundice, high peak of serum transaminases activity, hypoglycemia and low prothrombin activity, but no hepatic encephalopathy. Full recovery was observed in all cases from 3 to 12 months. CONCLUSIONS: Ecstasy is responsible for a relatively high number of cases of acute liver failure in young people. Therefore, the use of this drug should be investigated in all patients with severe hepatitis of unclear origin. Efforts must be made to advise young people of the risks of ecstasy consumption.

Adolescent↗
PubMed1998

Cytotoxic T-lymphocyte responses to HIV-1 reverse transcriptase (review).

Cytotoxic T lymphocytes (CTL) play an important role in the control of human immunodeficiency virus (HIV) infection. CTL responses have been demonstrated for most of the HIV gene products, predominantly gag, pol, and env-encoded proteins, and also for the regulatory proteins Nef, Tat, Vif, or Rev. The HIV-1 reverse transcriptase (RT), which derives from expression of the pol gene, is an important target of cellular immune responses in infected individuals. More than 40 different peptides containing RT-specific CTL epitopes have been identified. The most conserved and frequently detected are located in the 'fingers' and 'palm' subdomains of the enzyme, but other epitopes have been found in the 'thumb' and 'connection' subdomains as well as in the RNase H domain. Studies on the sequence variability and functional role of amino acids forming CTL epitopes are relevant for addressing important questions relative to viral escape from immmune control and the future design of anti-AIDS vaccines.

AIDS Vaccines↗
PubMed1998

Delayed clearance of serum HBsAg in compensated cirrhosis B: relation to interferon alpha therapy and disease prognosis. European Concerted Action on Viral Hepatitis (EUROHEP)

OBJECTIVE: The aim of this study was to evaluate the incidence, prognostic factors and clinical significance of delayed clearance of serum HBsAg in compensated cirrhosis B. METHODS: This was a retrospective cohort study of 309 consecutive white patients with biopsy-proved compensated cirrhosis type B. RESULTS: During a mean follow-up of 68 months, HBsAg loss occurred in 32 patients, including 16 (8%) of 196 untreated patients (mean annual incidence 0.8%), 8 (10%) of 82 interferon (IFN) alpha-treated patients and eight patients who had been treated with other antivirals or steroids. The 5-yr probability of HBsAg loss was 4% and 16% for untreated and IFN-treated patients, respectively (p = 0.0001). Cox's regression analysis identified hepatitis B e antigen-positivity at entry as the sole independent prognostic factor for HBsAg loss. Of the 32 patients who lost HBsAg, one (3%) subsequently developed hepatocellular carcinoma (HCC) and died, whereas, among the patients who remained HBsAg-positive, 11% developed HCC and 20% had died. The probability of HCC appearance was lower (p = 0.0137) and survival was longer (p = 0.0006) in patients who cleared HBsAg compared with patients with HBsAg persistence. CONCLUSION: The incidence of HBsAg loss is about 0.8% in cirrhosis type B. Prognostic factors for clearance of HBsAg are initial HBeAg positivity and therapy with alpha interferon. Patients with cirrhosis type B, who lose HBsAg, have a low risk for liver cancer or liver-related death.

Adult↗
PubMed1998

Analysis of pol gene heterogeneity, viral quasispecies, and drug resistance in individuals infected with group O strains of human immunodeficiency virus type 1.

Nucleotide sequences of the reverse transcriptase (RT) coding region have been compared in four new human immunodeficiency virus type 1 (HIV-1) group O isolates. Phylogenetic analysis of this pol region highlights a cluster of these four HIV-1 group O sequences with seven other group O isolates (5% intracluster nucleotide sequence diversity) similar to clusters classified as subtypes in HIV-1 group M (an average of 4.9% intrasubtype sequence diversity). Based on these analyses, this group O cluster has been designated subtype A-O. A longitudinal study of a heterosexual couple infected with group O (ESP1 and ESP2) allowed a detailed analysis of RT sequences (amino acids 28 to 219). Directed evolution and a slightly higher mutation frequency was observed in the RT sequences of patient ESP2, treated with antiretroviral drugs, than that from the untreated patient ESP1. Antiretroviral treatment also selected for specific substitutions, M184V and T215Y in the RT coding region, conferring resistance to 3'-dideoxy-3'-thiacytidine and zidovudine, respectively. A Gly98 to Glu RT substitution identified in the treated patient suggests a possible reversion of a nonnucleoside RT inhibitor-resistant phenotype. Using RT clones from this longitudinal study, both heteroduplex tracking assay and cloning-sequencing techniques were employed for an extensive genetic analysis of pol gene quasispecies. Amino acid substitutions (i.e., Phe-77 to Leu, Lys-101 to Glu, and Val-106 to Iso) associated with antiretroviral resistance were identified in RT clones from HIV-1 group O-infected patients not subjected to drug therapy or treated with unrelated drugs. Finally, phylogenetic relationships between RT clones of the treated ESP2 patient and those of the untreated ESP1 patient show how drug pressure can direct evolution of viral pol gene quasispecies independently of direct drug-resistant substitutions.

Adolescent↗
PubMed1997

[Serotypes of the human immunodeficiency virus type 1 in Madrid].

BACKGROUND: HIV-1 shows high genetic variability, mainly in the genomic region codifying the envelope proteins, which are the most immunogenic. This fact explains the high heterogeneity of antibodies against HIV-1 epitopes. Both genetic and serologic diversity has allowed to classify HIV-1 variants in several subtypes (genotypes and serotypes, respectively). The clinical and epidemiological significance of infection caused by each subtype remains to be clarified. PATIENTS AND METHODS: Serum samples from 154 HIV-seropositive individuals living in Madrid were studied. Serotyping was performed using 4 peptides belonging to the V3 env region. Epidemiological and clinical variables examined in these patients were the route of infection, the year in which HIV infection occurred, the country of birth, and the rate of disease progression (rapid versus slow). RESULTS: 148 (96.2%) samples could be serotyped, and the B class was recognized in 131 (88.5%) of them. Serotype A/C was found in 9 (6.1%). Two samples (1.3%) reacted to peptide E; however, both were also reactive against the B peptide, suggesting co-infection with B and E subtypes. Six samples were EIA-reactive for HIV-1/2 but were typed as HIV-2 alone. Infection with serotypes A/C was more frequent amongst immigrants, mainly in Africans. There was not association between any subtype and the route of infection neither a different rate of disease progression. CONCLUSION: HIV-1 serotype B is the most frequently found in HIV-seropositive individuals living in Madrid, without association with the route of infection or the clinical course of the disease. Serotypes A/C and E were found sporadically, mainly among immigrants.

Africa↗
PubMed1997

Hemodynamic and gas exchange responses to inhalation of nitric oxide in patients with the acute respiratory distress syndrome and in hypoxemic patients with chronic obstructive pulmonary disease.

OBJECTIVE: Inhalation of nitric oxide (NO) can improve oxygenation and decrease mean pulmonary artery pressure (MPAP) in patients with the acute respiratory distress syndrome (ARDS). It is not known whether inhaled NO exerts a similar effect in hypoxemic patients with chronic obstructive pulmonary disease (COPD). DESIGN: Prospective clinical study. SETTING: General intensive care unit in Sabadell, Spain. PATIENTS: Nine mechanically ventilated COPD patients (mean age 72 +/- 2 years; forced expiratory volume in 1 s 0.91 +/- 0.11 l) and nine ARDS patients (mean age 57 +/- 6 years; mean lung injury score 2.8 +/- 0.1). MEASUREMENTS AND RESULTS: We measured hemodynamic and gas exchange parameters before NO inhalation (basal 1), during inhalation of 10 ppm NO (NO-10), and 20 min after NO was discontinued (in basal 2) in the ARDS group. In the COPD group, these parameters were measured before NO inhalation (basal 1), during different doses of inhaled NO (10, 20, and 30 ppm), and 20 min after NO was discontinued (basal 2). A positive response to NO was defined as a 20% increment in basal arterial partial pressure of oxygen (PaO2). MPAP and pulmonary vascular resistance (PVR) decreased significantly, while other hemodynamic parameters remained unchanged after NO-10 in both groups. Basal oxygenation was higher in the COPD group (PaO2/FIO2 (fractional inspired oxygen) 190 +/- 18 mmHg) than in the ARDS group (PaO2/FIO2 98 +/- 12 mmHg), (p < 0.01). After NO-10, PaO2/FIO2 increased (to 141 +/- 17 mmHg, p < 0.01) and Qva/Qt decreased (39 +/- 3 to 34 +/- 3%, p < 0.01) in the ARDS group. There were no changes in PaO2/FIO2 and Qva/Qt when the NO concentration was increased to 30 ppm in the COPD group. In both groups, a correlation was found between basal MPAP and basal PVR, and between the NO-induced decrease in MPAP and in PVR. The NO-induced increase in PaO2/FIO2 was not correlated with basal PaO2/FIO2. In the ARDS group, six of the nine patients (66%) responded to NO and in the COPD group, two of nine (22%) (p = 0.05). CONCLUSIONS: NO inhalation had similar effects on hemodynamics but not on gas exchange in ARDS and COPD patients, and this response probably depends on the underlying disease.

Administration, Inhalation↗
PubMed1997

Effect of sucralfate on gastric intramucosal pH in critically ill patients.

OBJECTIVE: To determine whether sucralfate administration affects the tonometric measurement of gastric intramucosal pH (pHi). DESIGN: Non-randomized observational study. SETTING: General intensive care unit of a teaching hospital. PATIENTS: Twenty critically ill, mechanically ventilated, consecutively admitted patients requiring an arterial catheter and nasogastric tube. INTERVENTIONS: Tonometer placement and sucralfate administration. MEASUREMENTS AND MAIN RESULTS: We simultaneously determined tonometer saline PCO2 (PCO2i), arterial blood gases, pH of gastric juice and pHi. These parameters were evaluated immediately before sucralfate administration, and 2 h and 4 h after. We did not detect any change in either PCO2i or pHi after sucralfate administration (PCO2i: basal 6.4 +/- 1.7, 2 h 6.3 +/- 1.7, 4 h 6.3 +/- 1.7; pHi: basal 7.35 +/- 0.13, 2 h 7.36 +/- 0.12, 4 h 7.36 +/- 0.12). CONCLUSIONS: Sucralfate does not affect the tonometric measurement of PCO2i and pHi.

Adult↗
PubMed1997

Short-term effects of prone position in critically ill patients with acute respiratory distress syndrome.

OBJECTIVE: Changing the position from supine to prone is an emerging strategy to improve gas exchange in patients with the acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the acute effects on gas exchange, hemodynamics, and respiratory system mechanics of turning critically ill patients with ARDS from supine to prone. DESIGN: Open, prospective study. SETTING: General intensive care units. PATIENTS: 23 patients [mean age 56 +/- 17 (SD) years] who met ARDS criteria and had a Lung Injury Score > 2.5 (mean 3.25 +/- 0.3). INTERVENTIONS: The decision to turn a patient was made using a protocol based on impaired oxygenation despite the use of positive end-expiratory pressure and a fractional inspired oxygen (FIO2) of 1. MEASUREMENTS AND RESULTS: We measured gas exchange and hemodynamic variables in all patients and in 16 patients calculated respiratory system compliance when they were supine and 60 to 90 min after turning them to a prone position. This latter position was remarkably well tolerated and no clinically relevant complications or events were detected either during turning or while prone. The partial pressure of oxygen in arterial blood (PaO2)/FIO2 ratio improved from 78 +/- 37 mm Hg supine to 115 +/- 31 mm Hg prone (p < 0.001), and intrapulmonary shunt decreased from 43 +/- 11 to 34 +/- 8% (p < 0.001). Cardiac output and other hemodynamic parameters were not affected. Respiratory system compliance slightly improved from 24.7 +/- 10.2 ml/cmH20 supine to 27.8 +/- 13.2 ml/cmH20 prone (p < 0.05). An improvement in PaO2/FIO2 of more than 15% from changing from supine to prone was found in 16 patients (responders). Responders had more hypoxemia (PaO2/FIO2 70 +/- 23 vs 99 +/- 53 mm Hg in non-responders, p < 0.01), more hypercapnia (partial pressure of carbon dioxide in arterial blood (70 +/- 27 vs 64 +/- 9 mm Hg, p < 0.01) and a shorter elapsed time to the onset of ARDS and turning to the prone position (11.8 +/- 16 vs 32.8 +/- 42 days, p < 0.01). CONCLUSIONS: Turning critically ill, severely hypoxemic patients from the supine to the prone position is a safe and useful therapeutic intervention. Our data suggest that prone positioning should be carried out early in the course of ARDS.

Adult↗
PubMed1997

Liver transplantation in patients with Caroli's disease and recurrent cholangitis.

Caroli's disease is an uncommon congenital disorder of the intrahepatic biliary tree. It is characterized by multiple and segmental dilatations of the bile ducts. The clinical course of Caroli's disease is often complicated by recurrent episodes of bacterial cholangitis that seriously impair the patient's quality of life. Despite wide spectrum antimicrobial agents, medical treatment of cholangitis is frequently unsuccessful in patients with Caroli's disease due to the persistence of bacteria in dilatated bile ducts. Other therapies, including internal or external biliary drainages and various surgical or endoscopic procedures, have been used in the treatment of Caroli's disease, with poor results. There are no previous reports in the literature of liver transplantation for recurrent cholangitis in patients with Caroli's disease. We present two such cases, in which cholangitis is resolved.

Adult↗
PubMed1997

Reliability of a new recombinant immunoblot assay (RIBA HIV-1/HIV-2 SIA) as a supplemental (confirmatory) test for HIV-1 and HIV-2 infections.

The diagnosis of HIV infection is usually determined using serological methods. Positive results in a screening test should be confirmed with more specific supplementary assays, and the Western blot (WB) is the most frequently used. However, problems of WB, particularly in regard to the significance of indeterminate results, still remain. We evaluate a new recombinant HIV-1/2 antigen-based immunoblot (RIBA) as confirmatory assay in a panel of 190 clinical samples. The RIBA was much more sensitive and specific than WB. In particular, the test allows for a significant reduction in the number of indeterminate results and for more accurate distinction between HIV-1 and/or HIV-2 infections. Thus, these results make tests such as the RIBA instead of WB particularly attractive for validating anti-HIV EIA reactivity.

HIV Infections↗
PubMed1997

Early changes in hemoglobin and hematocrit levels after packed red cell transfusion in patients with acute anemia.

BACKGROUND: Equilibration of hemoglobin concentration after transfusion has been estimated to take about 24 hours, but some studies have shown that earlier measurements reflect steady-state values in persons who have not bled recently. This study was aimed at assessing the changes over time in hemoglobin concentration after transfusion in acutely anemic patients because of recent bleeding. STUDY DESIGN AND METHODS: Thirty-two normovolemic patients recovering from an acute bleeding episode who were no longer thought to be bleeding and who received a 2-unit red cell transfusion were studied. At baseline and 15, 30, 60, and 120 minutes and 24 hours after transfusion, hemoglobin concentration and hematocrit values were measured. RESULTS: The administration of 2 units of packed red cells elicited a 24-hour increase of 22.4 +/- 6.8 g per L in hemoglobin concentration. Hemoglobin values were not different at any of the defined posttransfusion times. Hematocrit levels experienced similar changes over time. Agreement between 15-minute and 24-hour values was excellent, as only 6 percent of patients exhibited a clinically significant difference (> 6 g/L) between the hemoglobin measurements. CONCLUSION: Hemoglobin and hematocrit values rapidly equilibrate after transfusion in normovolemic patients who are recovering from an acute bleeding episode. This fact would allow a rapid assessment of the effects of transfusion and of the recurrence of bleeding in patients remaining at risk.

Acute Disease↗