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Biomedical subjects

M Méndez

Publications and source records attributed to M Méndez.

At least 19 recordsLinked to original sources
PubMed2006

[Results of an outpatient major surgery program in ophthalmology].

PURPOSE: To evaluate the outcomes in our hospital of an ambulatory major surgery program in patients with a variety of different ocular pathologies. METHOD: This retrospective study includes 13,878 patients who underwent programmed surgery by the Department of Ophthalmology between September 1998 and December 2004. Different ophthalmological surgical procedures were performed as outpatient surgery in 11,187 patients, with cataract surgery (phacoemulsification) being the most frequent operation performed (8,155 cases). We have analysed several indicators (substitution, suspension, admission and readmission rates), as well as surgical yield and systemic and ocular complications which appeared within 72 hours after surgery. The variables were measured as relative frequencies. The evolution of complications during the study period was analysed by the Chi-square trend test. RESULTS: 13,878 patients had ophthalmic surgery during the study period; 11,187 had outpatient surgery with a global substitution ratio of 80.6%. The median surgical yield was 74.36%. The admission rate after surgery was 4.46% (499 patients), with 92.18% (460) of these requiring immediate admission. Twenty-one patients suffered from severe complications (cardiovascular, neurological, metabolic, infectious), representing a proportional risk of 1:532. Forty-five patients had less severe complications (arterial hypertension, nausea, vomiting, vasovagal syncope) that required admission to hospital. Ophthalmologic complications occurred in 79 cases (0.56%). CONCLUSIONS: Ambulatory major surgery (AMS) is an excellent organization model of multidisciplinary surgical assistance that makes it possible to treat well selected patients in an effective, safe and efficient manner. There is a low incidence of postoperative complications of variable severity despite following the optimum requisites, although fortunately mortality is practically absent.

Aged↗
PubMed2005

Weekly irinotecan plus UFT and leucovorin as first-line chemotherapy of patients with advanced colorectal cancer.

We evaluated the antitumoral efficacy and safety of CPT-11 125 mg/m2 (weekly 90 min i.v. infusion; days 1, 8 and 15) combined with UFT (oral combination of tegafur and uracil) 200 mg/m2/day plus leucovorin (LV) 45 mg/m2/day (both divided into three separate oral doses every 8 h, days 1-21) every 4 weeks as first-line chemotherapy of metastatic colorectal cancer (CRC). Fifty-three patients > or =18 years old with histologically confirmed diagnosis of advanced CRC and bidimensionally measurable disease were enrolled. Three patients (6%) showed CR and 8 patients (15%) showed PR (ORR = 21% (95% CI, 10-32). Stable disease was reported in 19 patients (36%) [tumor control rate = 57% (95% CI, 43-70)]. The median time to progression and overall survival were 7.9 and 18.2 months, respectively (1-year rate = 74%; 2-years rate = 26%). CPT-11/UFT/LV treatment was well tolerated: the most reported grade 3/4 toxicities were neutropenia (11% of patients) and delayed diarrhea (28% of patients). No significant differences in response rate, survival or toxicity were found between younger (< or =65 years) and older patients (> 65 years). Weekly CPT-11 plus UFT/LV was found effective and safe as first-line chemotherapy for metastatic CRC. The addition of CPT-11 to UFT/LV doubled the response rate compared to the results previously reported with UFT/LV, while myelosuppression remained low.

Adenocarcinoma↗
PubMed2003

Morgagni hernia: repair with a mesh using laparoscopic surgery.

The aim of this study is to present two patients diagnosed with diaphragmatic Morgagni hernia and treated by repairing the hernia defect with a mesh by laparoscopic surgery. We describe the placement of a double-layer mesh anchored with helicoidal staples to repair the hernia defect using laparoscopic surgery. Laparoscopic surgery allows repair of these defects whilst avoiding the disadvantages of a major laparotomy or a thoracotomy. The existence of double-layer meshes that can be placed in contact with the abdominal viscera allows the defect to be closed safely and without tension.

Child↗
PubMed2003

Paroxysmal atrial fibrillation prevention by pacing in patients with pacemaker indication.

AIMS: The prevent-atrial fibrillation (AF) registry analyses the clinical relevance and usefulness of the four preventive pacing algorithms, available in a family of cardiac stimulators, to prevent atrial fibrillation. METHODS AND RESULTS: This study is a prospective, non-randomized, multicentre registry. Patients are eligible for the registry if they have sick sinus syndrome (SSS) with or without pre-existing atrial fibrillation. The preventive pacing algorithms were programmed for each patient on an individual basis using the diagnostic features of the devices. In the period from April 2000 to April 2001 a total of 68 patients (33 male, 35 female) has been included in the registry in 14 hospitals in Spain. Mean age was 72+/-12 years and the pacemaker indication was SSS in 15 patients (22%) and SSS with paroxysmal AF in 53 patients (78%). The median AF burden for the total group (n=32) was significantly reduced from 3.9 to 1.3% (67%, P=0.034, Wilcoxon signed rank test). The decrease in AF burden was accompanied by a non-significant decrease in the median number of episodes per day from 1.47 to 0.64 (a decrease of 56%). The average atrial pacing % was increased from 72 to 78%. CONCLUSIONS: The prevent-AF registry demonstrated the usefulness of four preventive pacing algorithms in daily clinical practice. During the registry a significant reduction in AF burden and all other endpoints was observed. Dedicated diagnostics were key to adapting the optimal pacing therapy during follow-up.

Aged↗
PubMed2002

Precipitating/aggravating factors of porphyria cutanea tarda in Spanish patients.

Erythrocyte uroporphyrinogen decarboxylase (UROD) activity was measured to classify 118 Spanish patients with porphyria cutanea tarda (PCT) into three subtypes: sporadic-, familial- and type III-PCT. Seventy-four patients (63%) had eythrocyte UROD activity within the normal range (74% to 126% of the mean activity of 43 healthy controls) and were classified as sporadic-PCT (47%) or as type III-PCT (16%) whenever a family history of PCT was documented. Forty-four patients (37%) had decreased UROD activity and were classified as familial-PCT. The frequency of both familial-PCT and type III-PCT was higher than reported in other countries. The clinical expression of PCT was associated with the coexistence of two or more risk factors in 80% of the sporadic-PCT patients and in 89% of the familial-PCT patients. Hepatitis C virus and alcohol abuse were risk factors frequently found in these patients, being unrelated to age of onset of skin lesions. A heavy alcohol intake was the main risk factor for type III-PCT. Estrogens appeared as a precipitating factor for women with familial-PCT. The H63D mutation in the hemochromatosis type 1 gene was more frequently found than the C282Y mutation. Both mutations appeared to play a role as precipitating factors in sporadic-PCT when associated with hepatitis C virus infection and alcohol abuse.

Adult↗
PubMed2001

Cyclizations of enynes catalyzed by PtCl2 or other transition metal chlorides: divergent reaction pathways.

1-en-6-ynes react with alcohols or water in the presence of PtCl2 as catalyst to give carbocycles with alkoxy or hydroxy functional groups at the side chain. The reaction proceeds by anti attack of the alkene onto the (eta2-alkyne)platinum complex. The formation of the C-C and C-O bonds takes place stereoselectively by trans addition of the electrophile derived from the alkyne and the nucleophile to the double bond of the enyne. Formation of five- or six-membered carbo- or heterocycles could be obtained from 1-en-6-ynes depending on the substituents on the alkene or at the tether. Although more limited in scope, Ru(II) and Au(III) chlorides also give rise to alkoxy- or hydroxycyclization of enynes. On the basis of density functional theory (DFT) calculations, a cyclopropyl platinacarbene complex was found as the key intermediate in the process. In the presence of polar, nonnucleophilic solvents, 1-en-6-ynes are cycloisomerized with PtCl2 as catalyst. Formation of a platinacyclopentene intermediate is supported by DFT calculations. The reaction takes place by selective hydrogen abstraction of the trans-allylic substituent. Cycloisomerization of enynes containing disubstituted alkenes could be carried out using RuCl3 or Ru(AsPh3)4Cl2 in MeOH.

Journal Article↗
PubMed2001

Acute ethanol administration differentially modulates mu opioid receptors in the rat meso-accumbens and mesocortical pathways.

Biochemical and pharmacological evidence suggest that the dopaminergic mesolimbic system plays a key role in mediating the reinforcing properties of alcohol and other drugs of abuse. Alcohol reinforcement and high alcohol drinking behavior have been postulated to be partially mediated by a neurobiological mechanism involving the alcohol-induced activation of the endogenous opioid system. The aim of this work was to study the effect of the in vivo acute administration of ethanol on mu (mu) opioid receptors in the rat dopaminergic meso-accumbens and mesocortical pathways by quantitative receptor autoradiography. [(3)H]DAMGO binding was significantly decreased in the ventral tegmental area (VTA) 30 min after ethanol administration. A small ethanol-induced reduction was observed in the shell region of the nucleus accumbens 1 h after exposure. In contrast, 2 h after ethanol administration, [(3)H]DAMGO binding was significantly increased in the frontal and prefrontal cortices. The observed changes correlated well with high ethanol plasma levels. Our results suggest that the reinforcing properties of ethanol may be partially mediated by mechanisms involving the ethanol-induced down- and up-regulation of mu receptors in the dopaminergic mesolimbic system. Mu receptors in the VTA and the frontal and prefrontal cortices may be involved in the in vivo acute responses to ethanol and could play a key role in modulating the dopaminergic activity of the mesocortical pathway in response to the drug. In contrast, the contribution of both mu and delta receptors in the nucleus accumbens might be relevant in these processes.

Alcoholism↗
PubMed2001

Reaction of vinyl epoxides with palladium-switchable bisnucleophiles: synthesis of carbocycles.

The selective activation of substrates I, potential bisnucleophiles, was achieved by using different palladium catalysts. The synthetic potential of this strategy has been demonstrated in the regiodivergent synthesis of carbocycles from substrates of type I, bearing malonate-type pronucleophiles and an alkenyl stannane, with vinyl epoxides. A selective palladium-catalyzed reaction of I with the vinyl epoxide gives rise to an allylic alcohol, which, after activation as a carbonate, led to the cyclization product by a second palladium-catalyzed reaction. The transmetalation process is favored with palladium-catalysts without phosphines or arsines as the ligands. On the other hand, the use of palladium complexes with PPh3 as the ligand inhibits the transmetalation pathway and promotes the nucleophilic attack of the malonate-type anions on the intermediate (eta 3-allyl)-palladium complexes.

Journal Article↗
PubMed2001

Interactions between sleep and epilepsy.

Sleep is one of the best-documented factors influencing the expression of seizures and interictal discharges. Janz studied the relation between seizures and the sleep/wake cycle and divided the epilepsies into three categories: nocturnal, awakening, and diffuse. Since then, the effect of sleep on the ictal and interictal manifestations of epilepsy has been studied extensively. Many seizures are activated by sleep or arousal from sleep. Interictal discharges are also seen more commonly during sleep, with the greatest activation seen during nonrapid eye movement sleep. Sleep not only increases the frequency of epileptiform abnormalities, but also may alter their morphology and distribution. Sleep deprivation also facilitates both epileptiform abnormalities and seizures. Seizures, on the other hand, also impact sleep. Epileptic patients demonstrate multiple sleep abnormalities, including an increased sleep latency, fragmented sleep, increased awakenings and stage shifts, and an increase in stages 1 and 2 of nonrapid eye movement sleep. These disturbances may in turn be modulated by antiepileptic treatment. This review summarizes the interactions between sleep and epilepsy, including the timing of seizures during the sleep/wake cycle, the influence of sleep on various seizure disorders, the effects of sleep deprivation, and the changes in sleep patterns caused by seizures and their treatment.

Action Potentials↗
PubMed2001

Hepatitis C virus and GBV-C/hepatitis G virus in Argentine patients with porphyria cutanea tarda.

To investigate hepatitis C virus (HCV) and GBV-C/hepatitis G virus (HGV) genotype prevalence among HCV-infected porphyria cutanea tarda (PCT) patients, 19 HCV-infected patients with associated PCT were studied. A control group of 53 age-matched HCV-infected patients without associated PCT was selected. Eighteen of the 19 serologically positive HCV-PCT patients showed HCV RNA in serum. Genotype 1b was the most prevalent among both HCV-PCT patients (72.2%; 13/18) and age-matched HCV controls (50.9%; 27/53). Such different genotypic prevalence failed to reach statistical significance (chi(2) with Yates' correction, p = 0.19). The single HCV-PCT patient without detectable HCV RNA was also infected with genogroup 3 GBV-C/HGV. This GBV-C/HGV RNA prevalence (5.3%) among HCV-PCT patients is not statistically different from that observed among Argentine blood donors (5.5%; 11/200). To our knowledge, these results show for the first time the molecular epidemiology of both HCV and GBV-C/HGV associated to PCT in America.

Adult↗
PubMed2000

A second locus for an axonal form of autosomal recessive Charcot-Marie-Tooth disease maps to chromosome 19q13.3.

Autosomal recessive Charcot-Marie-Tooth disease (CMT) represents a heterogeneous group of disorders affecting the peripheral nervous system. The axonal form of the disease is designated as "CMT type 2" (CMT2), and one locus (1q21.2-q21.3) has been reported for the autosomal recessive form. Here we report the results of a genomewide search in an inbred Costa Rican family (CR-1) affected with autosomal recessive CMT2. By analyzing three branches of the family we detected linkage to the 19q13.3 region, and subsequent homozygosity mapping defined shared haplotypes between markers D19S902 and D19S907 in a 5.5-cM range. A maximum two-point LOD score of 9.08 was obtained for marker D19S867, at a recombination fraction of.00, which strongly supports linkage to this locus. The epithelial membrane protein 3 gene, encoding a PMP22 homologous protein and located on 19q13.3, was ruled out as being responsible for this form of CMT. The age at onset of chronic symmetric sensory-motor polyneuropathy was 28-42 years (mean 33.8 years); the electrophysiological data clearly reflect an axonal degenerative process. The phenotype and locus are different from those of demyelinating CMT4F, recently mapped to 19q13.1-13.3; hence, the disease affecting the Costa Rican family constitutes an axonal, autosomal recessive CMT subtype (ARCMT2B).

Adult↗
PubMed2000

F-actin fiber distribution in glomerular cells: structural and functional implications.

BACKGROUND: Glomerular distention is associated with cellular mechanical strain. In addition, glomerular distention/contraction is assumed to influence the filtration rate through changes in filtration surface area. A contractile cytoskeleton in podocytes and mesangial cells, formed by F-actin-containing stress fibers, maintains structural integrity and modulates glomerular expansion. In this study, the glomerular cell distribution of F-actin and vimentin filaments was studied in normal control and nine-month streptozotocin-diabetic rats. Results in situ were compared with observations in tissue culture. METHODS: Microdissected rat glomeruli were perfused to obtain a physiological 25% glomerular expansion over the basal value. Fixation was done without change in glomerular volume. Dual fluorescent labeling of F-actin and vimentin was carried out, and samples were examined by confocal laser scanning microscopy. RESULTS: The podocyte cell bodies and their cytoplasmic projections, including the foot processes, contained bundles of vimentin-containing fibers. Except for a thin layer at the base of foot processes, they did not demonstrate F-actin. While mesangial cells in culture had F-actin as long stress fibers resembling tense cables, mesangial cells stretched in situ contained a maze of short tortuous F-actin fibers organized in bundles that often encircled vascular spaces. This fibrillar organization was disrupted in diabetic glomeruli. CONCLUSION: Mesangial cells, but not podocytes, contain a cytoskeleton capable of contraction that is disorganized in long-term diabetes. Together with previous observations, the distribution of this cytoskeleton suggests that mesangial cell contraction may be involved in the redistribution of glomerular capillary blood flow, but not substantially in the modulation of glomerular distention. Disorganization of stress fibers may be a cause of hyperfiltration in diabetes.

Actins↗
PubMed2000

Skeletal muscle abnormalities associated with occupational exposure to mercury vapours.

There is scarce information on the possible effects of chronic exposure to mercury on skeletal muscle. Dental personnel are frequently exposed to inhalation of metallic mercury vapours. The skeletal muscle of five technicians and one dentist (females, age 36-55) was studied. All of them presented symptoms of chronic mercury poisoning. Needle biopsy was taken from the quadriceps femoris muscle and samples were prepared for light microscope histochemistry and for transmission electron microscopy. Selective atrophy of type IIB muscle fibres was found in patients, and in one of them there was fibre grouping. Most of the muscles showed increased fibre area per capillary. Atrophy was confirmed by the ultrastructural study, demonstrating increase of intermyofibrillar spaces, loss of myofibrils or complete disappearance in some fibres, and sarcolemmal foldings. Splitting of the fibres was also found. Some capillaries were altered, showing endothelial infoldings into the lumen, thickened basement membrane and partial or total occlusion. The alterations found in muscle may be secondary to nerve damage, to ischemia caused by capillary lesion and/or to a direct effect of mercury on muscle fibre proteins.

Adult↗
PubMed2000

[Bronchiolitis obliterans with organizing pneumonia secondary to chemotherapy in a child with primary pericardial sarcoma].

The uncommon bronchiolitis obliterans organizing pneumonia can be idiopathic or caused by infection or medications. We report a 5 year old boy with pericardial sarcoma that was treated with chemotherapy (vincristine, doxorubicin, etoposide, cyclophosphamide) and radiotherapy. During the third cycle of chemotherapy, he developed progressive cough and dyspnea, needing oxygen therapy. Chest X-ray examination showed bilateral infiltrates. After discarding infectious etiologies, an open lung biopsy was performed, and the pathological examination showed a bronchiolitis obliterans organizing pneumonia. He was treated with prednisolone for 7 days, followed by prednisone for additional 45 days. He continued with fluticasone propionate as maintenance and remains in good condition with a chest X-ray showing mild interstitial images, after seven months of follow up.

Antineoplastic Agents↗
PubMed1999

Phase II study of ifosfamide plus vinorelbine in metastatic breast cancer patients previously treated with combination chemotherapy.

Forty-six patients were included in a phase II study to evaluate the response rate and toxicity of a combination of ifosfamide and vinorelbine in metastatic breast cancer patients previously treated with one or more regimens of chemotherapy. Treatment consisted of ifosfamide 1.6 g/m(2) IV days 1-3 (with mesna) and vinorelbine 25 mg/m(2) IV days 1 and 8, every 3 weeks up to 6 cycles. The median age was 55 years (range 40-76), the World Health Organization (WHO) performance status was 0-1 in 93% of the patients and 2 in the remaining 7%. In all, 43% had received two or more previous lines of chemotherapy, and 91% had been treated with anthracyclines. Forty-four patients were evaluable for response, and all patients for toxicity. The overall response rate was 36.4% [95% confidence interval (CI) 22.4-52.2]. Stabilization was observed in 20.4% and progression in 43.2%. The median time to progression was 25 weeks (95% CI 14-36). Median relative dose intensity (=actual received dose intensity/planned dose intensity) was 0.99 for ifosfamide and 0. 80 for vinorelbine. The main toxicity was hematological, with 63% of the patients experiencing grade 3-4 neutropenia. With a moderate toxicity, this is an active regimen that may be taken into consideration in pretreated metastatic breast cancer patients when further chemotherapy is indicated.

Adult↗
PubMed1999

A shuttle walk test for assessment of functional capacity in chronic heart failure.

BACKGROUND: Peak oxygen uptake (peak VO(2)) is a reference parameter in the assessment of functional capacity of patients with chronic heart failure, but the procedure for cardiopulmonary exercise testing with expired gas analysis is complex and expensive, so more simple and available methods are desirable. METHODS: We compared the usefulness of a time-limited walk test, the 6-minute walk test (6-MT), with that of a symptom-limited walk test, the shuttle walk test (SWT), in the evaluation of patients with moderate to severe chronic heart failure. We prospectively studied 46 clinically stable patients in New York Heart Association class II to IV heart failure with left ventricular ejection fraction <40% (aged 53 +/- 10 years, ejection fraction 23% +/- 8%, New York Heart Association functional class 2.8 +/- 0.7). Each patient performed two 6-MT, two SWT and a cardiopulmonary exercise testing within 2 weeks. RESULTS: We found a close correlation between distance walked in SWT and peak VO(2 ) (r = 0.83, P <.001) and a moderate correlation between distance in 6-MT and peak VO(2) (r = 0.69, P <.001). Both walk tests showed to be reproducible after just one practice walk. All patients who walked > 450 m in SWT had a peak VO(2) >14 mL/kg/min. The overall discriminatory accuracy for SWT distance was greater than that for 6-MT distance for predicting a peak VO(2 ) <14 mL/kg/min (area under receiver operator characteristic curves 0.97 and 0.83 respectively, P =.02). Stepwise multivariate regression analysis, including clinical, exercise testing, echocardiographic, radionuclide-angiographic, and rest hemodynamic data, showed that distance walked in SWT was the only independent predictor of peak VO(2) (P <.001) and the strongest predictor of percent achieved of age- and sex-predicted peak VO(2) (%PVO(2)) (P <.001), with only age offering additional information (P =.02). CONCLUSIONS: The SWT shows to be a feasible and safe method to evaluate patients with chronic heart failure that strongly and independently predicts peak VO(2) and %PVO(2.) This symptom-limited walk test seems to be more useful than 6-MT in the assessment of functional capacity in these patients.

Adult↗
PubMed1999

Amiodarone is a pharmacologically safe drug for porphyrias.

Amiodarone (AD) is an effective antidysrythmic drug, however, there can be serious side effects, such as hepatic and neurological alterations, as well as skin photosensitization, as seen in porphyrias. Clinical signs in porphyrias might be triggered by the so-called porphyrinogenic drugs. Without sound basis, Amiodarone has been classified as an unsafe drug for porphyric patients. The aim of this work has been to study the effect of AD, both in vivo and in vitro, on heme metabolism. In the in vivo assays, the activities of 5-aminolevulinate synthetase (ALA-S), ALA dehydratase (ALA-D), porphobilinogenase (PBGase) and PBG-deaminase (PBG-D) in blood, liver, and kidney; hepatic and fecal porphyrins, urinary ALA, PBG and porphyrins in male mice strain CF1 treated with AD (100 mg i.p. daily) for 1 week and 1 month, were measured. No significanat differences were found for any of these parameters in the AD treated animals as compared to controls. In the in vitro experiments human blood, and mice blood, liver, and kidney, were used to measure the activities of ALA-S, ALA-D, PBGase, PBG-D and uroporphyrinogen decarboxylase, in the presence of varying concentrations of AD (0.0172-4.304 mM). AD did not modify any of the enzyme activities. All of the above biochemical parameters were studied in 17 cardiac patients under AD treatment for 3 to 20 years. Neither the activities of the heme enzymes, nor the levels of precursors and porphyrins in urine and plasma were altered. These findings clearly demonstrate that AD is a pharmacologically safe drug and can be used for the treatment of associated pathologies in porphyrias.

5-Aminolevulinate Synthetase↗