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Biomedical subjects

M Rodríguez

Publications and source records attributed to M Rodríguez.

At least 289 records · Page 16Linked to original sources
PubMed1994

Prevalence and significance of hepatitis C viremia in chronic active hepatitis B.

OBJECTIVES: To assess the prevalence and significance of HCV infection in patients with chronic active hepatitis B. METHODS: We studied clinical and histological activity in 132 patients with chronic active hepatitis B, 17 of whom were co-infected by HCV. Serum HBV-DNA was determined by dot-blot hybridization and polymerase chain reaction (PCR) and serum HCV-RNA was determined by ELISA-2, RIBA-2, and reverse transcription PCR (RT-PCR). RESULTS: HBV-DNA was detected by dot-blot in five of 17 (29.4%) patients in the HCV-RNA-positive group and in 64 of 115 (55.6%) in the HCV-RNA-negative group (p < 0.05). The low levels of HBV replication (assessed by PCR) were similar in both groups. Mean levels of serum AST, ALT, and gamma-globulin, as well as mean scores of liver damage, were significantly higher among HCV-RNA-positive patients than among HCV-RNA-negative patients. CONCLUSIONS: 1) Concomitant HCV infection occurs frequently in patients with chronic active hepatitis B; 2) co-infection of HBV and HCV is more common in the absence of HBV-DNA detected by dot-blot hybridization; 3) liver disease seems to be more severe in patients with concomitant HBV and HCV infection, even though the number of replicative HBV patients was lower in the group of HCV-infected patients. This suggests that the role of HCV is probably important as the cause of persistent liver disease. 4) The detection of HBV-DNA by dot-blot and HCV-RNA by PCR could help to establish whether HBV, HCV, or both contribute to liver injury.

Adult↗
PubMed1994

[Olivopontocerebellar atrophy and Parkinson's disease: diagnostic problems].

Clinical diagnoses of Parkinson's disease (PD) is highly inaccurate. Olivopontocerebellar atrophy (OPCA) is a major source of diagnostic confusion. We have studied the clinical characteristics of 50 patients with PD, 24 patients with OPCA judged by the presence of selective atrophy of the cerebellum and brainstem (diagnosed by CT brain scan) and 30 normal controls of similar age. The typical triad of PD, tremor, rigidity and akinesia, did not distinguish among patients from either group. The presence of severe postural imbalance and reflex myoclonus (in OPCA but not in PD) were the 2 most highly discriminative clinical features.

Aged↗
PubMed1993

Formation and characterization of cyclosporine-loaded nanoparticles.

The commercially available formulations of cyclosporine (cyclosporin A, CyA) are associated with acute hemodynamic changes that result in high nephrotoxicity. Among colloidal vectors, nanoparticles (NPs) are receiving much attention as potential drug carriers that would avoid the therapeutic risks of conventional formulations. Two different mechanisms for obtaining polymeric NPs loaded with CyA were studied with regard to their preparation and physicochemical characterization. Isobutyl-2-cyanoacrylate monomer (IBCA) was polymerized, whereas poly-E-caprolactone (PCL, a preformed polymer) was precipitated; both reactions took place in an aqueous medium containing Pluronic F-68 (polyoxypropylene polyoxyethylene block copolymer) as a surface active agent. The encapsulation efficiencies were 78.49 +/- 5.87 and 84.85 +/- 5.02%, respectively, and they remained stable over a wide range of drug concentrations. The polymeric NP had average sizes of 81 +/- 25 and 95 +/- 25 nm for poly-IBCA and PCL, respectively, as confirmed by photon correlation spectroscopy. Poly-IBCA NPs were built from oligomers with molecular weights of 157 to 2644 that joined to form a polymeric nanomatrix. In vitro activity of the drug and the carrier was tested by inhibition of lymphocyte proliferation induced by Concanavalin A. Drug-loaded PCL NPs and free CyA inhibited lymphocyte proliferation by 91.40 and 86.19%, respectively. However, drug-free NPs also exhibited statistically significant (p < 0.05) immunosuppressive activity.

Animals↗
PubMed1993

Value of ellipsoid volume masking in myocardial tomography.

The circumferential profile technique, used to obtain a bull's eye image from short axis slices in myocardial perfusion tomography, requires isolation of the reconstructed volume from other neighbouring structures that may take up the radiopharmaceutical used. If this is not possible, some regional artefacts can be introduced in the polar map that do not represent the actual myocardial perfusion at the corresponding level. In this case report we describe a method for volume masking that permits the myocardium inside in ellipsoidal volume to be enclosed. This technique is compared with the spherical method used in a Sophy 20P system in a case with impaired perfusion of an inferolateral segment and an extracardiac "hot" structure located in the same area. The results obtained show the usefulness of our method in such cases.

Algorithms↗
PubMed1993

Correlation between computed tomography and voltage and current source density spectral EEG parameters in patients with brain lesions.

In a group of patients with space-occupying brain lesions, CT measurements were correlated with absolute power (AP) and relative power (RP) of the delta, theta, alpha and beta EEG bands, calculated from the raw EEG potentials (EEGp) and from the Laplacian estimates also called "current source densities" (CSD). Rank correlations were calculated between the number of abnormal values in each band and the following CT measures: volume of the lesion and of the edema, density of the edema, percentage of ventricular collapse and midline shift. Abnormal spectral values are those which are significantly higher than the norm for the same age, in the delta and theta bands, and significantly lower in the alpha and beta bands. Spectral parameters obtained from the CSD showed higher correlations with CT measures than those calculated from the EEGp. In the Laplacian, all CT measures had a significant correlation with delta AP. Theta AP was significantly correlated with the volume and density of the edema, as well as with midline shift. Significant correlations were also observed with delta and alpha RP. However, changes in RP were considered to be a consequence of the increase in delta AP. Canonical correlation analyses between AP and RP calculated from EEGp or CSD and the first 3 CT measures showed that the volume of the lesion was only correlated with delta AP and RP. The volume and density of the edema showed a significant correlation with delta, theta and alpha AP calculated from EEGp and only with theta and alpha AP in the Laplacian. Since the EEGp tends to produce a more extensive and diffuse picture of abnormality, whereas the Laplacian acts as a spatial filter emphasizing local sources over distant sources, we concluded that edema is related not to delta activity, but to the theta and alpha power.

Adolescent↗
PubMed1993

Treatment of chronic hepatitis C with recombinant interferon alfa-2b for nine months.

This randomised, controlled trial was designed to assess the response to a nine month course of interferon (IFN) alfa-2b, starting with a higher than usual dose. Forty eight patients received IFN 5 million units (MU) three times a week for eight weeks followed by 3 MU three times weekly for seven months; 25 patients in the control group received no treatment. The overall response to treatment was 68.7%, an improvement over other studies, but the high rate of relapse (85% in patients who responded) suggested that a nine month treatment period was insufficient in most cases. Histological improvement was seen in more than 80% of responders to interferon, including a reduction in inflammatory activity, necrosis, and fibrosis.

Adolescent↗
PubMed1993

Response related factors in recombinant interferon alfa-2b treatment of chronic hepatitis C.

In an analysis of the clinical and laboratory variables that can influence the response to interferon alfa-2b treatment, 48 patients with chronic hepatitis C virus infection received interferon 5 million units (MU) subcutaneously three times weekly for eight weeks followed by 3 MU three times weekly for seven months. Response related factors on univariate analysis were found to be age > 40 years, non-parenteral source of infection, pretreatment positive antinuclear antibodies (ANA), cirrhosis, and high serum iron, ferritin, gamma glutamyl transferase, and IgM. An independent predictive value (multivariate analysis) was also found for cirrhosis, ANA, serum iron, and ferritin. A baseline aspartate aminotransferase/alanine aminotransferase ratio of 0.5 and a striking increase during interferon treatment were associated with a complete response.

Adolescent↗
PubMed1993

Triiodothyronine receptor complex in developing rat brain and pituitary.

In vitro saturation analysis combined with nuclear 3,5,3'-triiodothyronine (T3) quantification was used to examine the changes in T3 binding parameters in rat pituitary and cerebrocortical nuclei from fetal day 14 to postnatal day 20. T3 receptors were first detectable in neuronal, glial, and pituitary nuclei on fetal days 14, 17, and 18, respectively. Thereafter T3 receptor concentrations in neuronal, glial, and pituitary nuclei increased throughout the developmental period studied, reaching maximal levels during neonatal life (1,129, 1,025, and 635 fmol/mg DNA, respectively). T3 levels in pituitary, neuronal, and glial nuclei also increased during development there being a 35-, 34-, and 120-fold rise between fetal days 16-18 and the 20th postnatal day. Endogenous T3 receptor occupancy throughout the experimental period increased six- to ninefold in the three types of nuclei. The presence of T3 receptor complex in the pituitary and cerebrocortical nuclei during perinatal development lends further support to the hypothesis that T3 may be an important factor in determining the differentiation and development of these cells.

Aging↗
PubMed1993

Evaluation of complement activity by an enzyme immunoassay.

An ELISA-type assay useful for the evaluation of the complement activity in serum is described. Aggregated pooled human IgG (IgGn) prepared so as to exclude large and small aggregates, to resemble soluble circulating immune complexes, was used to coat polystyrene microwells to serve as initiator of complement activation. Fresh serum, at different dilutions, as the source of the complement to be evaluated was added and the plate incubated 90 min at 37 degrees C. Then, a peroxidase-labeled antihuman C3c antibody was added to react with the bound C fragments. This was followed by 2,2'-azino-di-3-ethyl benzothiazoline sulfonic acid (ABTS), as the color reagent used for detection of the enzyme activity. In this system, theoretically, the levels of activating and regulatory complement components are evaluated up to the level of C3 splitting. The assay was applied in healthy volunteers to set normal values and in 15 patients suffering from systemic lupus erythematosus making possible the differentiation of those with normal and low complement levels.

Complement Activation↗
PubMed1993

Cognitive functioning in male polydrug abusers with and without family history of alcoholism.

We investigated the family history of alcoholism as a potential contributor to cognitive dysfunction in polydrug abusers. A sample of 62 male polydrug users whose main drug of use was heroin included no one with which comorbid antisocial behavior varied by family history of alcoholism. They were compared on a battery of cognitive tests. Polydrug users with positive histories tended to perform worse on several cognitive measures than those with negative family histories, but these tendencies were not statistically significant. The current findings support the hypothesis that cognitive deficiencies observed in previous studies of persons with positive family histories of alcoholism may, in part, be attributable to a failure to exclude individuals with diagnoses of antisocial behavior.

Adult↗
PubMed1993

Cognitive functioning, family history of alcoholism, and antisocial behavior in female polydrug abusers.

Family history of alcoholism and antisocial behaviour had both independent and synergic negative relationships with abstract verbal reasoning for a group of 42 female polydrug abusers whose main drug was heroin. This finding suggests that the observed lower cognitive performance may reflect the family history of alcoholism or antisocial behaviour rather than just drug abuse and is consistent with theories predicting a relative deficiency in high language skill by persons with antisocial personality disorders.

Adult↗
PubMed1993

Test-retest reliability of EEG spectral parameters during cognitive tasks: I. Absolute and relative power.

We analyzed test-retest reliability of Absolute (AP) and Relative Power (RP) during rest and during two cognitive tasks: one verbal, the search for a synonym, and the other consisting of mental arithmetic calculations. Under all conditions during the experiment the subjects had their eyes open. The experiment was performed twice, with a month's interval between each trial. Monopolar recordings were obtained in F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5, T6 and Cz vs A1A2. Differences between sessions were observed mainly during rest with eyes open in the lapha band, with higher AP during the first session. During rest it is extremely difficult to control for the state of vigilance, anxiety and thinking. However, during cognitive tasks a more rigid control of the state of vigilance and thinking is obtained. Therefore, AP and RP are very reliable parameters for analyzing EEG during mental tasks. Comparisons between conditions were also made. The only significant differences observed were in delta AP in the second session, with more power during the cognitive tasks in C3 and O2. MANOVAs using the values of AP in the four bands showed significant differences between conditions in C3, C4, P3, O2 and T4. Several factors that may be involved in the origin of delta activity, including eye movements, slow potential shifts and the inhibition of cholinergic projections to the cortex, are discussed.

Adult↗
PubMed1993

Test-retest reliability of EEG spectral parameters during cognitive tasks: II. Coherence.

We analyzed test-retest reliability of EEG coherence during rest and during two cognitive tasks: one verbal, the search for a synonym, and the other consisting of mental mathematical calculations. The experiment was performed twice, with a month's interval between each session. Coherence between all pairwise combinations of the EEG recorded in 15 leads was computed for delta, theta, alpha and beta bands. Comparing the changes observed between sessions for each condition, few significant changes were observed during rest, and the condition which manifests the most changes was calculation. Differences between conditions were observed in the second session in P3-T5, P3-T6, P3-T3, P4-T6, P4-T5, P4-Cz and Cz-T6 delta coherences ordered in a decreasing order from calculation to synonyms to rest. In order to ascertain whether the pattern of coherences across the head in each subject varied in relation to the session and the condition, we computed the correlation coefficients between all coherences values for one condition versus the other condition per band. For all subjects correlation coefficients near unity were observed between conditions in each session. However, correlation coefficients between sessions, even for the same condition, were much lower. We also computed the correlation coefficients for the coherence values between subjects in the same condition separately for each session. Correlation coefficients between subjects were much higher in the second session than in the first one.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1993

Hypersensitivity to latex, chestnut, and banana.

The incidence of latex-allergic patients is probably higher than suspected. A spectrum of IgE-dependent allergic reactions to latex products including urticaria, rhinitis, asthma, angioedema, and life-threatening anaphylaxis has been increasingly reported in recent years. We describe three patients with rubber hypersensitivity and allergy to fruit (banana and chestnut). Immediate positive responses were obtained in prick tests with latex, banana, and chestnut extracts. Histamine release was positive and specific IgE antibodies to all three extracts were detected by fluorescence radioimmunoassay. In the RAST-inhibition studies, the extract of latex inhibited the binding of chestnut and banana, but chestnut and banana extracts did not inhibit the binding of latex. These results suggest a sensitivity to crossreacting antigens in latex allergy associated with allergy to certain fruits.

Adult↗
PubMed1993

Nucleic acid hybridisation and polymerase chain reaction in the diagnosis of infectious animal diseases.

The authors describe and summarise the use of nucleic acid hybridisation and polymerase chain reaction (PCR) technologies in the diagnosis of animal diseases. PCR is a powerful biological tool which enables exponential enzymatic amplification in vitro of a given deoxyribonucleic acid sequence. This technique is currently used to study the molecular pathogenesis of many infectious diseases and also for diagnosis. PCR is usually more sensitive than conventional methods and does not require complex facilities, and will therefore soon become the preferred technology of laboratory diagnosticians, field veterinarians and health officers.

Animals↗