[Hepatotoxicity due to commonly-used drugs].
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Analgesics↗
Biomedical subjects
R Alcántara
Publications and source records attributed to R Alcántara.
Theoretical study of the morphologically originated noise associated with the transmittance of a precipitation system.
In this paper we present the results of a computational study that analyses the relationship between the noise associated with the optical transmittance of a system of particles and the morphology of such particles. Computational algorithms have been developed in order to represent the different morphologies within a wide range of sizes. By using this methodology, it has been possible to study the morphology of particles in a virtual system, therefore avoiding the distortions that would inevitably be present in a real system. As a consequence of this study, a classification of the morphologies observed has been made according to the amount of noise they would add to the transmittance of a system of particles. The theoretical results obtained are in good agreement with the available experimental data obtained in real systems.
Journal Article↗
Antidepressant-induced hepatotoxicity.
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Antidepressive Agents↗
Experimental study of precipitating systems; computerised analysis of the optical transmittance and associated noise.
The change of the transmittance in a precipitant system has been measured by using a focused laser beam into a precipitation cell in which the precipitate was generated by an injection technique. We have monitored the evolution of the transmittance on several precipitation processes with different chemicals (PbI2, PbSO4, BaSO4 and BaC2O4) and quantities of precipitated mass (20.0, 17.5, 15.0, 12.5 and 10.0 mg). The noise associated to the transmittance signal has been obtained by a numerical procedure based on computer analysis, finding that it provides information about particle shape features and nucleation kinetics.
Journal Article↗
Study of precipitant systems by computerised simulation. Influence of optical elements on the noise associated with the transmittance.
The transmittance signal of a precipitant system measured with a focused laser beam carries associated noise coming from several sources. In this work, we have studied the influence of the focal parameters (wavelength, focal length and prefocused radius of the beam) on the maximum noise reached in equivalent nucleation processes. For this purpose, a simulation program of precipitating systems, designed in FORTRAN 90, has been developed. The program generates simulated transmittances, which are processed by another computer program to extract associated noise. Wide ranges of values of the focal parameters have been analysed, finding relationships between the maximum noise and the focal parameters. They have been justified in connection with the changes observed in the radial parameters, which define the size and shape of the focused path.
Journal Article↗
Analysis and localization of epileptic events using wavelet packets.
This article compares results obtained in previous studies using time-frequency representations (Wigner-Ville, Choi-Williams and Parametric) and the wavelet transform with those obtained with wavelet packet functions to show new findings about their quality in the analysis of ECoG recordings in human intractable epilepsy: data from 21 patients have been analyzed and processed with four types of wavelet functions, including Orthogonal, Biorthogonal and Non-Orthogonal basis. These functions were compared in order to test their quality to represent spikes in the ECoG. The energy based on the wavelet coefficients to different scales was also calculated. The best results were found with the biorthogonal-6.8 wavelet on 5-7 scales, which gave 0.92 sensitivity, but with a high percentage of false positives; this representation was highly correlated with spike events on time and duration. To improve these results we have studied the wavelet packet coefficients energy. We found that reconstruction wavelet packet coefficients at 4 and 9 nodes contain significant information to characterize the spike event. These nodes' reconstruction coefficients were multiplied and this product was highly correlated with spikes events on time and duration. With this procedure we improved the sensitivity up to 0.96 with the same biorthogonal-6.8 wavelet at four levels. With this technique we do not sacrifice computation time: 896 samples are processed at only 0.16 s, so that it is possible to show the spike scattering path on line, because 896 samples (7 s)/16 channels are processed at 3.13 s.
Adult↗
Flutamide-induced hepatotoxicity: report of a case series.
OBJECTIVE: To evaluate the characteristics of flutamide induced hepatotoxicity. MATERIAL AND METHODS: In this retrospective study we have analyzed all cases of flutamide hepatotoxicity submitted to the Andalucian Registry of drug-induced liver disease. Data were collected using a structured reporting form. Causality assessment was performed using two clinical scales: the standard CIOMS scale and the recently developed María and Victorino scale. RESULTS: Nine of 185 patients (4.9%) were identified. In 8 male patients, mean age 75 years (range 65-83), flutamide was indicated for palliative therapy of disseminated prostatic carcinoma, and in one young female (14 years) was given for the treatment of facial hirsutism. The mean duration of the flutamide therapy was 151 days (range 4-443). All patients presented with overt liver injury, the most frequent features being asthenia, anorexia, weight loss, nausea, vomiting and jaundice. No patient showed hypersensitivity features. In two patients (22%) the hepatic damage evolved to fulminant liver failure, one of them undergoing a liver transplantation and the other subsequently died. An additional patient died of a non-hepatic related cause when his liver function was improving. Causality assessment by the two clinical scales did not exclude any case, but the two patients who died where classified as unlikely by the María and Victorino scale. CONCLUSIONS: Flutamide can induce severe acute hepatitis, probably due to an idiosyncratic metabolic mechanism. Liver tests monitoring should probably be mandatory during the first months of flutamide therapy and the drug withdrawn if transaminases began to increase.
Adolescent↗
Chronic liver injury related to use of bentazepam: an unusual instance of benzodiazepine hepatotoxicity.
Liver injury induced by benzodiazepines is rare and is classified as an unpredictable or idiosyncratic hepatotoxic reaction. Early reports indicated that in most cases the pattern of liver injury was cholestatic. We describe three patients with persistent increases in liver transaminase levels after several weeks of treatment with bentazepam, a benzodiazepine marketed in Spain for anxiety disorders. In all cases withdrawal of the drug was followed by resolution of transaminase level abnormalities. A liver biopsy (done in one patient only) showed histological evidence of severe chronic active hepatitis. In conclusion, these findings, together with two previously published case reports, suggest that a benzodiazepine can cause chronic hepatitis and argue in favor of using liver function tests to monitor all patients taking bentazepam.
Administration, Oral↗
Effects of interferon-beta on plasma lipid and lipoprotein composition and post-heparin lipase activities in patients with chronic hepatitis C.
BACKGROUND: Interferon therapy has been shown to induce lipid abnormalities. AIM: We assessed the effects of interferon-beta on the lipoprotein profile and post-heparin lipase activities in 26 normolipaemic patients with chronic hepatitis C. METHODS: Interferon-beta was administered subcutaneously at doses of 6 x 106 U (units) three times a week, over 6 months, and lipoproteins and post-heparin lipases were measured at baseline and at the end of therapy. RESULTS: Plasma triglycerides increased by 21% due to preferential enrichment in those contained in the very low density lipoprotein (VLDL) and low density lipoprotein (LDL) fractions. The concentration of cholesterol decreased slightly in the high density lipoprotein (HDL) subfractions. Lipoprotein lipase, but not hepatic lipase activity decreased by a 36%, and this change showed a significant negative correlation with changes in plasma triglycerides. Five patients (19.5%) responded to interferon-beta therapy. The lipoprotein profile was no different between responders and non-responders to therapy. CONCLUSIONS: Interferon-beta treatment in normolipaemic patients with chronic hepatitis C induced moderate disturbances in plasma lipoproteins, associated with inhibition of lipoprotein lipase activity.
Adult↗
[Chronic cholestasis as a presentation form of portal cavernoma].
A 37 year-old-woman was evaluated in 1993 for a chronic asymptomatic cholestasis. An endoscopic retrograde cholangiopancreatography showed the biliary tract compressed, and a mesenteric angiogram disclosed that the cause of biliary obstruction was a portal cavernoma. In addition, large esophageal varices with "red spots" were observed at endoscopy. Propranolol and ursodeoxicolic acid were started and the patient has remained asymptomatic to date. The biliary features of portal cavernoma are reviewed, as well as its pathogenesis, diagnosis and management. Portal cavernoma should be considered in the differential diagnosis of chronic cholestasis.
Adult↗
[Comparative computer tomography study/ pathology for the evaluation of the invasive depth of laryngeal carcinomas].
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Carcinoma↗
[HELLP syndrome. Analysis of 2 cases].
HELLP syndrome (Hemolysis, Elevated Liver Enzymes, Low Platelets), one of the gestational diseases of the third trimester of pregnancy associated to eclampsia or preeclampsia, has a varied clinical expression, that include poor symptomatic patterns with malaise and/or dyspepsia, even several patterns with fatal outcome. We show two cases with clinical and laboratory criterion of HELLP syndrome, but with different clinical presentations. It's analyzed the pathogenicity, clinical-pathological expression, course and therapeutics options in HELLP syndrome.
Adult↗
Hydrodynamic properties and immunological identification of the sodium- and chloride-coupled glycine transporter.
We have recently reported the purification of the native sodium- and chloride-coupled glycine transporter from pig brain stem (López-Corcuera, B. Vázquez, J., and Aragón, C. (1991) J. Biol. Chem. 266, 24809-24814). This preparation is essentially homogeneous and contains a unique 100-kDa polypeptide based on electrophoretic migration under denaturing conditions. In this paper we report the hydrodynamic characterization of the native transporter, solubilized in two different detergents, as well as the immunological identification of the protein. On the basis of results obtained from size-exclusion chromatography, we calculated the Stokes radii of transporter 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS) and transporter-cholate complexes to be 5.5 and 6.0 nm, respectively. In addition, from H2O/D2O sucrose density gradient sedimentation analysis, we calculated the molecular weight of protein-detergent complexes to be 115,000 and 160,000 in CHAPS and cholate, respectively, and the molecular weight of the protein moiety as 86,000. Finally, polyclonal antibodies raised against the 100-kDa polypeptide were found to immunoprecipitate specifically glycine transport activity. Taken together, the results reported herein corroborate the identity of the 100-kDa band as the sodium- and chloride-coupled glycine transporter and also suggest that in its native state the transporter is a monomeric protein.
Amino Acid Transport Systems, Neutral↗
L-glutamate transporter derived from mRNAs of primary glial cultures: expression in Xenopus laevis oocytes.
A high-affinity sodium-dependent L-glutamate transporter was expressed in Xenopus oocytes after microinjection of poly(A)+ RNA from primary astrocyte cultures from rat brain cortex. mRNA-induced L-glutamate transport was saturable by substrate and shows kinetic features similar to those found in intact glial cell preparations. L-Glutamate accumulation was prevented by rising the external K+ concentration or by coincubation with L-, D-aspartate or D-glutamate. After fractionation by sucrose density gradient, the mRNA encoding for the expressed L-glutamate transporter from glial cells was found in fractions containing messages of 2.05-2.9 kilobases (kb) in length.
Alkaline Phosphatase↗
Group-selective reagent modification of the sodium- and chloride-coupled glycine transporter under native and reconstituted conditions.
Glycine transporter from rat brain stem and spinal cord is inactivated by specific sulfhydryl reagents. Modification of lysine residues also promotes a decrease of the transporter activity but in a lesser extent than that promoted by thiol group reagents. Mercurials showed a more marked inhibitory effect than maleimide derivatives. SH groups display a similar reactivity for p-chloromercuribenzenesulfonate (pCMBS) and mersalyl in synaptosomal membrane vesicles and proteoliposomes reconstituted with the solubilized transporter. However, different reactivity is observed with N-ethylmaleimide (MalNEt), the greatest effect being attained in membrane vesicles. The rate of inactivation by pCMBS and MalNEt is pseudo-first-order showing time- and concentration-dependence. pCMBS and MalNEt decrease the Vmax for glycine transport and to a lesser extent act on the apparent Km. Treatment with dithiothreitol (DTT) of the transporter modified by pCMBS results in a complete restoration of transporter activity indicating that the effect exercised by the reagent is specific for cysteine residues on the protein. It is concluded that SH groups are involved in the glycine transporter function and that these critical residues are mostly located in a relatively hydrophilic environment of the protein.
4-Chloromercuribenzenesulfonate↗
Beta 1-adrenoceptors in rat hepatoma. Desensitization by isoproterenol and phorbol-myristate-acetate.
The beta-adrenergic responsiveness of hepatocytes obtained from hypothyroid rats and of a transplantable hepatoma cell line (AS-30D) were studied by measuring the accumulation of cyclic AMP. The potency order for agonists in hepatocytes was: isoproterenol greater than epinephrine much greater than norepinephrine whereas in the hepatoma cells the potency order was: isoproterenol greater than norepinephrine greater than or equal to epinephrine. The effect of isoproterenol was antagonized in hepatocytes by low concentrations of ICI 118551 and only partially by concentrations of atenolol as high as 100 microM. In hepatoma cells the effect of isoproterenol was inhibited by both antagonists with the potency order atenolol greater than ICI 118551. These data indicate that in hepatocytes the effect is mediated by beta 2-adrenoceptors whereas in hepatoma cells it is through beta 1-adrenoceptors. Preincubation of hepatoma cells with isoproterenol or phorbol-myristate-acetate diminished the subsequent beta-adrenergic responsiveness of the cells. Interestingly, when both isoproterenol and phorbol-myristate-acetate were present during the preincubation the beta-adrenergic desensitization observed was bigger than that induced by any of these agents alone.
Adenylyl Cyclases↗
[Amoxycillin-clavulanic acid in patients with spontaneous bacterial peritonitis].
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Amoxicillin-Potassium Clavulanate Combination↗
[Diagnosis of venous thrombosis by using radioisotopes].
Thromboembolism problem is a grave complication which occurs with great frequency in patients hospitalized in a critical state. The association between periferical venous thrombosis and the thromboembolic accident is plainly demonstrated, although the accurate establishment of the clinical diagnosis of phlebothrombosis is only feasible in 50% of the cases. In the present work, we describe the methodology and the experience which we have acquired with the use of radioisotops in the diagnosis of these problems. We studied 64 patients to whom in the supine position we injected into a vein in both heels, from 3 to 5 millicuries of 99m-Tecnecio, practicing three stages: dynamic venography, a static study, and a pulmonary gammagram. In the normal cases, we clearly identified the tracts of the principal femural, iliac, and the inferior third of the inferior vena cava veins. In the abnormal studies, we observed the obstructive process manifested by the absence of radioactivity in the affected venous tract, with appearence of collateral circulation, definitive data which establishes with certainty the diagnosis. It can be concluded that the method is rapid and easily carried out, meaning that it could be a routine practice in all of those patients who are suspected of having this problem.
Adult↗