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BACKGROUND: The effects of stretching exercises in fibromyalgia (FM) deserves further study. OBJECTIVE: To evaluate the effectiveness of a Physical Self-Care Support Program (PSCSP), with emphasis on stretching exercises, in the treatment of FM. METHODS: Forty-five women with FM were randomized to the PSCSP (n= 23) or to a control group (n= 22). The PSCSP consisted of weekly 90-minute learning sessions over 10 weeks, providing instructions on wellness, postural techniques, and active stretching exercises to be done at home. The control group was monitored through 3 medical appointments over 10 weeks and included in a waiting list. The primary outcomes were the Fibromyalgia Impact Questionnaire (FIQ), the Visual Analogue Scale (VAS) for pain, and the Sit and Reach Test (SRT) at the end of the study. RESULTS: Nineteen and 21 patients completed the trial in PSCSP and control groups, respectively. After 10 weeks, the PSCSP group showed significantly better FIQ (difference between adjusted means, -13.64, 95% CI, -21.78 to -5.49, P= 0.002) and SRT scores (7.24 cm, 3.12 to 11.37, P= 0.001) than the control group, but no significant difference in pain VAS (-1.41, -3.04 to 0.22, P= 0.088). Analysis using multiple imputation (MI) and delta-adjusted MI for missing outcomes rendered similar results. CONCLUSIONS: A PSCSP emphasizing stretching exercises significantly improved FIQ and SRT scores, and may be a helpful therapy for FM.
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Fibromialgia , Terapia por Ejercicio/métodos , Femenino , Fibromialgia/terapia , Humanos , Dolor , Autocuidado , Encuestas y Cuestionarios , Resultado del TratamientoRESUMEN
Some patients with clinically diagnosed penile fracture actually have a false fracture (no tunica albuginea tear found at surgery). Although previous reports indicate that these patients often do not report hearing a snapping sound (henceforth sound) at injury, there are no studies of the sound's role in this differential diagnosis. To assess if the sound's absence increased the likelihood of intraoperatively diagnosing a false fracture, we retrospectively analyzed 65 consecutive clinically diagnosed penile fracture patients between January 2008 and December 2017, using surgical diagnosis of penile fracture as outcome variable and sound as main predictor, including as covariates age, presentation delay, immediate detumescence after injury, and whether injury occurred during sexual intercourse. Fifty-six patients had penile fracture (86.2%), and most (40, 71.4%) reported the sound, whereas two of the nine patients with false fracture reported the sound (22.2%, p = 0.007, Fisher's exact test). Bayesian logistic regression revealed that the sound was associated with surgical diagnosis of penile fracture (relative odds ratio = 4.25), and the probability of penile fracture fell from 92 to 74% when the sound was not reported among patients injured during intercourse experiencing immediate detumescence. This study followed PROCESS (Preferred Reporting of Case Series in Surgery) guidelines.
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Enfermedades del Pene , Pene , Teorema de Bayes , Humanos , Masculino , Enfermedades del Pene/diagnóstico , Enfermedades del Pene/cirugía , Pene/lesiones , Pene/cirugía , Estudios Retrospectivos , Rotura/diagnóstico , Rotura/cirugíaRESUMEN
Due to blood derivative requirements, many patients with hemophilia were exposed to Hepatitis C virus infection (HCV) before the availability of HCV testing. We report a 46-year-old male with Hemophilia A with a hepatitis virus C infection since 2004 causing a cirrhosis. Due to a hepatopulmonary syndrome, he received a liver allograph using a factor VIII replacement protocol, after eradicating the virus C. He had a good postoperative evolution, and no more factor VIII was required after transplantation until his last assessment.
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Hemofilia A/complicaciones , Hepatitis C/complicaciones , Cirrosis Hepática/cirugía , Trasplante de Hígado/métodos , Factor IX/administración & dosificación , Factor VIII/administración & dosificación , Hemofilia A/terapia , Humanos , Cirrosis Hepática/etiología , Masculino , Persona de Mediana EdadRESUMEN
Due to blood derivative requirements, many patients with hemophilia were exposed to Hepatitis C virus infection (HCV) before the availability of HCV testing. We report a 46-year-old male with Hemophilia A with a hepatitis virus C infection since 2004 causing a cirrhosis. Due to a hepatopulmonary syndrome, he received a liver allograph using a factor VIII replacement protocol, after eradicating the virus C. He had a good postoperative evolution, and no more factor VIII was required after transplantation until his last assessment.
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Humanos , Masculino , Persona de Mediana Edad , Trasplante de Hígado/métodos , Hepatitis C/complicaciones , Hemofilia A/complicaciones , Cirrosis Hepática/cirugía , Factor IX/administración & dosificación , Factor VIII/administración & dosificación , Hemofilia A/terapia , Cirrosis Hepática/etiologíaRESUMEN
Methanol is used in transesterification reaction for biodiesel production, being an important quality parameter to evaluate the purity of the final product. Methanol concentrations higher than 0.20% (m/m) reduce the biofuel efficiency. The Brazilian, United States, and European standards recommend the reference method based on gas chromatography with flame ionization detection, which involves a time-consuming procedure and requires high-cost equipment. In this work, it is proposed a simple and low cost spot test based on digital images acquired with a smartphone camera for the determination of methanol in biodiesel. The procedure was based on the oxidation of methanol to formaldehyde and subsequent reaction with Schiff reagent, resulting in a violet product. Analytical signals were based on the reflected radiation measured on the G channel (RGB system), which refers to the complementary color of the reaction product. Linear responses were obtained within 20-500â¯mgâ¯kg-1 and 500-2000â¯mgâ¯kg-1 methanol for 600 and 150⯵L of sample aqueous extracts, respectively. The coefficient of variation (nâ¯=â¯10) and the limit of detection (99.7% confidence level) were estimated as 4.8% and 10â¯mgâ¯kg-1 (600⯵L of sample), respectively. The procedure requires only 75⯵g of potassium permanganate, 6â¯mg of oxalic acid, and 1.5â¯mg of p-rosaniline and generates ca. 1.2â¯mL of residue per determination. The results agreed with those obtained by the reference procedure at the 95% confidence level, demonstrating that the proposed method is an alternative for routine analysis of the biofuel.
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INTRODUCTION: Aqueous shunt has emerged as an alternative technique to trabeculectomy, which is considered the standard treatment for glaucoma surgery. Currently, it is mainly indicated after failure of trabeculectomy or in some types of glaucoma with high risk of failure. However, there is still controversy regarding its effectiveness compared to trabeculectomy. METHODS: We searched in Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. RESULTS AND CONCLUSIONS: We identified five systematic reviews including nine studies overall, of which four were randomized trials. We concluded that aqueous shunt might increase the qualified success compared to trabeculectomy, but it is not clear whether it has any effect on the rest of the critical outcomes for decision-making because the certainty of the evidence is very low.
INTRODUCCIÓN: La derivación acuosa ha surgido como una técnica alternativa a la trabeculectomía, la cual se considera el tratamiento estándar para cirugía de glaucoma. Actualmente, su principal indicación es en el glaucoma con trabeculectomía fallida o en algunos tipos de glaucoma con alto riesgo de fracaso. Sin embargo, aún existe controversia con respecto a su efectividad en comparación con la trabeculectomía. MÉTODOS: Realizamos una búsqueda en Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud, la cual es mantenida mediante el cribado de múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Extrajimos los datos desde las revisiones identificadas, analizamos los datos de los estudios primarios, realizamos un metanálisis y preparamos una tabla de resumen de los resultados utilizando el método GRADE. RESULTADOS Y CONCLUSIONES: Identificamos cinco revisiones sistemáticas que en conjunto incluyeron nueve estudios primarios, de los cuales, cuatro corresponden a ensayos aleatorizados. Concluimos que la derivación acuosa podría aumentar el éxito calificado en comparación con la trabeculectomía, pero que no está claro si tiene algún efecto sobre el resto de los desenlaces críticos para la toma de decisión, porque la certeza de la evidencia es muy baja.
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Implantes de Drenaje de Glaucoma , Glaucoma/cirugía , Trabeculectomía/métodos , Bases de Datos Factuales , Humanos , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del TratamientoRESUMEN
INTRODUCTION: Aqueous shunt has emerged as an alternative technique to trabeculectomy, considered the standard for glaucoma surgery. Currently, it is mainly indicated after failure of trabeculectomy or in glaucoma with high risk of failure. The Ahmed valve and the Baerveldt implant are the most commonly used aqueous shunts. However, it is not clear whether there are differences between them. METHODS: To answer this question we used Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. RESULTS AND CONCLUSIONS: We identified five systematic reviews including 10 studies overall, of which two were randomized trials. We concluded the Ahmed valve probably achieves a lower decrease in intraocular pressure, might lead to less qualified success and probably needs more reinterventions than the Baerveldt implant. Regarding safety profile, the Ahmed valve is not clearly superior or inferior to the Baerveldt implant.
INTRODUCCIÓN: La derivación acuosa ha surgido como una técnica alternativa a la trabeculectomía, considerada la cirugía de elección en pacientes con glaucoma. Actualmente, se considera que la principal indicación de esta técnica es ante el fracaso de la trabeculectomía o en tipos de glaucoma que tienen alto riesgo de fracasar. La válvula Ahmed y el implante Baerveldt son las derivaciones acuosas más utilizadas. Sin embargo, no está claro cuáles son las diferencias entre estas dos alternativas. MÉTODOS: Para responder esta pregunta utilizamos Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud a nivel mundial, la cual es mantenida mediante búsquedas en múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Extrajimos los datos desde las revisiones identificadas, reanalizamos los datos de los estudios primarios, realizamos un metanálisis y preparamos una tabla de resumen de los resultados utilizando el método GRADE. RESULTADOS Y CONCLUSIONES: Identificamos cinco revisiones sistemáticas que en conjunto incluyeron 10 estudios primarios, de los cuales dos son ensayos aleatorizados. Concluimos que la válvula Ahmed probablemente logra una menor disminución de la presión intraocular; podría lograr un menor éxito calificado y probablemente necesita más reintervenciones que el implante Baerveldt. Respecto al perfil de seguridad, la válvula Ahmed no se presenta claramente superior ni inferior al implante Baerveldt.
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Implantes de Drenaje de Glaucoma , Glaucoma/cirugía , Trabeculectomía/métodos , Bases de Datos Factuales , Humanos , Presión Intraocular , Implantación de Prótesis/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto , Trabeculectomía/instrumentación , Resultado del TratamientoRESUMEN
Benzodiazepines are widely used in primary health care, and their prolonged use is an important problem given the medical consequences particularly in older adults, such as dependence, cognitive impairment, and risk of falls, among others. Primary care doctors generally have few tools to help with managing withdrawal from benzodiazepines. We conducted a review of the best available evidence on practical strategies to avoid dependence at the time of the initial prescription, and to help the patient with prolonged and probably dependent use. We found ten relevant systematic reviews showing evidence in favor of the use of multifaceted prescription strategies, gradual dose reduction, standardized letters, standardized counseling, pharmacotherapy and cognitive behavioral psychotherapy. For benzodiazepine withdrawal, a simple strategy that can be effective and long-lasting is to inform patients of the need to reduce consumption, giving them in writing the withdrawal guideline, indicating the possible effects of withdrawal and its solution. Given the available evidence, an integrated and step-by-step model is proposed for the management of the benzodiazepine user, from prescription to withdrawal.
Las benzodiacepinas son fármacos ampliamente utilizados en atención primaria de salud. Su uso prolongado se ha convertido en un problema relevante dadas las consecuencias médicas que ocasionan, especialmente en adultos mayores. Entre otras, estas son: dependencia, deterioro cognitivo y riesgo de caídas. Además, los médicos que trabajan en atención primaria cuentan con pocas herramientas para ayudar al paciente en su deshabituación. Se realizó una búsqueda y revisión de la mejor evidencia disponible sobre estrategias prácticas para el médico no especialista en adicciones, para evitar la dependencia al momento de la prescripción inicial y en el paciente con uso prolongado y probablemente dependiente. Se encontraron 10 revisiones sistemáticas relevantes que mostraron evidencia a favor del uso de estrategias multifacéticas en la prescripción, disminución progresiva, cartas y consejería estandarizadas, farmacoterapia y psicoterapia cognitiva conductual. Una estrategia sencilla, eficaz y duradera para prescribir benzodiacepinas es informar al paciente de la necesidad de reducir su consumo, dándole por escrito la pauta de retirada, señalando sus posibles efectos y su solución. Debido a la evidencia disponible, se propone un modelo integrado y escalonado para el manejo del paciente usuario de benzodiacepinas, desde su prescripción hasta su descontinuación.
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Benzodiazepinas/efectos adversos , Síndrome de Abstinencia a Sustancias/terapia , Trastornos Relacionados con Sustancias/rehabilitación , Anciano , Ansiolíticos/administración & dosificación , Ansiolíticos/efectos adversos , Benzodiazepinas/administración & dosificación , Humanos , Atención Primaria de Salud/métodosRESUMEN
INTRODUCTION: Trabeculectomy is considered the standard for glaucoma surgery. Postoperative scarring is one the factors associated with surgery failure. Different antimetabolites have been used in order to reduce this risk, particularly 5-fluorouracil and mitomycin C. Although both are considered effective, it is not clear if they are different in terms of success of trabeculectomy and adverse effects. METHODS: To answer this question we used Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. RESULTS AND CONCLUSIONS: We identified four systematic reviews including 17 studies overall, of which 12 were randomized trials. We concluded mitomycin C might be more effective in reducing intraocular pressure and increasing qualified success compared to 5-fluorouracil. However, its use might be associated to a higher risk of complications.
INTRODUCCIÓN: La trabeculectomía es considerada la intervención de elección en pacientes con glaucoma con indicación de manejo quirúrgico. Dentro de los factores asociados al fracaso de este tratamiento se encuentra la cicatrización postoperatoria. Para disminuir este factor se han usado distintos antimetabolitos, en particular el 5-fluorouracilo y la mitomicina C. Si bien ambos se consideran efectivos, no está claro si existen diferencias entre ambos en relación al éxito de la trabeculectomía y los efectos adversos. MÉTODOS: Para responder esta pregunta utilizamos Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud, la cual es mantenida mediante búsquedas en múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Extrajimos los datos desde las revisiones identificadas, reanalizamos los datos de los estudios primarios, realizamos un metanálisis, preparamos tablas de resumen de los resultados utilizando el método GRADE. RESULTADOS Y CONCLUSIONES: Identificamos cuatro revisiones sistemáticas que en conjunto incluyen 17 estudios primarios, de los cuales, 12 corresponden a ensayos aleatorizados. Concluimos que el uso de mitomicina C podría lograr una mayor disminución de la presión intraocular e incrementar la tasa de éxito calificado en comparación con el 5-fluorouracilo. Sin embargo, su uso podría asociarse a una mayor incidencia de complicaciones.
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Fluorouracilo/administración & dosificación , Glaucoma/cirugía , Mitomicina/administración & dosificación , Trabeculectomía/métodos , Antimetabolitos/administración & dosificación , Cicatriz/prevención & control , Humanos , Presión Intraocular , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
Resumen Introducción: La colecistectomía laparoscópica es una de las intervenciones quirúrgicas más frecuentes en nuestro país. La diarrea poscolecistectomía es una entidad poco reconocida, con una prevalencia descrita entre el 0,9 y 35,6%, sin embargo, en Chile esto no ha sido claramente definido. Objetivo: Determinar la prevalencia y características de la diarrea poscolecistectomía laparoscópica electiva en una muestra de pacientes chilenos. Material y métodos: Se aplicó una encuesta telefónica estructurada sobre consistencia y frecuencia de deposiciones, entre 4 y 6 meses después de la intervención, a los pacientes adultos operados de colecistectomía laparoscópica electivamente entre diciembre de 2014 y marzo de 2015. Se definió como «diarrea poscolecistectomía¼ la presencia de deposiciones líquidas o inusualmente disgregadas que hubiesen comenzado posteriormente a la intervención y se estableció el término de «diarrea prolongada¼ como la duración de síntomas mayor de 4 semanas. Resultados: Se encuestó a 100 pacientes (73% de mujeres). La prevalencia global de diarrea poscolecistectomía fue del 35% (n = 35). La prevalencia de pacientes con diarrea prolongada fue del 15% (n = 15). En el grupo con diarrea prolongada, se observó resolución completa de esta en el 57% de los pacientes (n = 8) en un plazo medio de 99 ± 29 días. Conclusión: La diarrea poscolecistectomía es una entidad frecuente en nuestra población, con una alta prevalencia dentro de los primeros 28 días posteriores a la intervención. En la mayoría de los pacientes se resuelve en los primeros 6 meses.
Abstract Introduction: Laparoscopic cholecystectomy (LC) is one of the most common surgical procedures in our country. Postcholecystectomy diarrhea is an unrecognized entity, with a reported prevalence between 0.9 and 35.6%, nonetheless in Chile this has not been clearly defined. Objective: To determine the prevalence and characteristics of diarrhea following elective laparoscopic cholecystectomy in our institution. Material and methods: A structured questionnaire about consistency and defecation frequency was applied to adult patients summited to an elective LC between December 2014 and February 2015, by a telephone survey within 4 and 6 months after the surgical procedure. Postcholecystectomy diarrhea was defined as the presence of liquid or unusually disrupted faecal material beginning after LC. Persistent diarrhea was established when diarrhea continued for a period longer than four weeks. Results: One hundred patients were included (73% women). The overall prevalence of postcholecystectomy diarrhea was 35% (n = 35). The prevalence of patients with persistent diarrhea was 15% (n = 15). In the group of patients with persistent diarrhea, complete resolution was observed on 57% of the cases (n = 8) within an average period of 99 ± 29 days. Conclusion: Post cholecystectomy diarrhea is a frequent condition in our population, with a high prevalence within the first 28 days after LC. In most patients it resolved within 6 months.
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Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Colecistectomía Laparoscópica/efectos adversos , Diarrea/epidemiología , Factores de Tiempo , Chile , Prevalencia , Encuestas y Cuestionarios , Factores de Riesgo , Síndrome Poscolecistectomía , Diarrea/etiologíaRESUMEN
Several techniques have emerged as complement or replacement for trabeculectomy, the standard surgery for glaucoma. Device-modified trabeculectomy is a recently developed technique whose results compared to the classical technique have not been fully defined. To answer this question, we used Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We identified eight systematic reviews including 34 studies overall. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. We concluded device-modified trabeculectomy probably leads to greater overall success rate and may decrease intraocular pressure more than classical surgery. In addition, this technique would probably have a better safety profile than standard trabeculectomy.
En los últimos años, diversas técnicas han surgido como complemento o reemplazo para la trabeculectomía, cirugía estándar en el manejo del glaucoma. La trabeculectomía modificada con dispositivo es una técnica reciente cuyos resultados en comparación con la técnica clásica aún no han sido del todo definidos. Para responder esta pregunta utilizamos Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud, la cual es mantenida mediante búsquedas en múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Identificamos ocho revisiones sistemáticas que en conjunto incluyen 34 estudios aleatorizados. Extrajimos los datos desde las revisiones identificadas, reanalizamos los datos de los estudios primarios, realizamos un metanálisis y preparamos tablas de resumen de los resultados utilizando el método GRADE. Concluimos que la trabeculectomía modificada con dispositivo probablemente se asocia a un mayor éxito completo y que podría disminuir la presión intraocular más que la cirugía clásica. Además, está técnica probablemente tendría un mejor perfil de seguridad que la terapia estándar.
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Glaucoma/cirugía , Presión Intraocular , Trabeculectomía/métodos , Humanos , Trabeculectomía/efectos adversos , Trabeculectomía/instrumentación , Resultado del TratamientoRESUMEN
RESUMO JUSTIFICATIVA E OBJETIVOS: Sabe-se que a fibromialgia é uma síndrome musculoesquelética caracterizada por dor crônica e generalizada. Considerando que a dor é um sintoma que traz implicações diretas na vida dos pacientes acometidos, o objetivo deste estudo foi avaliar a dor e a qualidade de vida de pacientes com fibromialgia para melhor compreender a correlação entre essas variáveis. MÉTODOS: Estudo transversal com 45 mulheres, com idade entre 30 e 55 anos, em tratamento estável no último mês que antecedeu a seleção, sendo excluídas as que estavam em tratamento fisioterapêutico, faziam uso de recursos auxiliares da marcha e/ ou tinham doenças reumatológicas autoimunes ou relevantes comorbidades sem controle. A avaliação foi realizada através de ficha de entrevista, Questionário de Impacto da Fibromialgia, Índice de Dor Generalizada e escala analógica visual. Os dados foram analisados através dos testes de Correlação de Pearson e t de Student, aceitando-se níveis de significância estatística acima de 95%. RESULTADOS: foram observados elevados valores no Questionário de Impacto da Fibromialgia, Índice de Dor Generalizada e escala analógica visual além de uma correlação linear entre os índices de dor e qualidade de vida. CONCLUSÃO: A dor está associada à diminuição da qualidade de vida de fibromiálgicos.
ABSTRACT BACKGROUND AND OBJECTIVES: It is known that fibromyalgia is a musculoskeletal syndrome characterized by chronic and widespread pain. Considering that pain has direct implications on affected patients' lives, this study aimed at evaluating pain and quality of life of fibromyalgia patients to better understand the correlation between such variables. METHODS: Cross-sectional study with 45 females aged between 30 and 55 years, in stable treatment in the month previous to selection, being excluded those under physiotherapeutic treatment, using walking aids and/or with autoimmune rheumatologic diseases or relevant uncontrolled comorbidities. Patients were evaluated with interview records, Fibromyalgia Impact Questionnaire, Widespread Pain Index and visual analog scale. Data were analyzed by Pearson Correlation and Student t tests, with statistical significance above 95%. RESULTS: There have been high scores in Fibromyalgia Impact Questionnaire, Widespread Pain Index and visual analog scale, in addition to linear correlation between pain scores and quality of life. CONCLUSION: Pain is associated to impaired quality of life of fibromyalgia patients.
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One-third to half of patients taking clozapine suffer from refractory symptoms despite adequate treatment. Among other adverse effects, clozapine-induced hypersalivation (CIH) occurs in approximately half of all patients. This is a case of a 30-year-old male with refractory schizophrenia; in this patient, the remission of residual positive symptoms, as well as the reduction of CIH, was achieved by treatment with clozapine augmented with amisulpride.
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The aim of this study was to compare iterative and direct solvers for estimation of marker effects in genomic selection. One iterative and two direct methods were used: Gauss-Seidel with Residual Update, Cholesky Decomposition and Gentleman-Givens rotations. For resembling different scenarios with respect to number of markers and of genotyped animals, a simulated data set divided into 25 subsets was used. Number of markers ranged from 1,200 to 5,925 and number of animals ranged from 1,200 to 5,865. Methods were also applied to real data comprising 3081 individuals genotyped for 45181 SNPs. Results from simulated data showed that the iterative solver was substantially faster than direct methods for larger numbers of markers. Use of a direct solver may allow for computing (co)variances of SNP effects. When applied to real data, performance of the iterative method varied substantially, depending on the level of ill-conditioning of the coefficient matrix. From results with real data, Gentleman-Givens rotations would be the method of choice in this particular application as it provided an exact solution within a fairly reasonable time frame (less than two hours). It would indeed be the preferred method whenever computer resources allow its use.
RESUMEN
The aim of this study was to compare iterative and direct solvers for estimation of marker effects in genomic selection. One iterative and two direct methods were used: Gauss-Seidel with Residual Update, Cholesky Decomposition and Gentleman-Givens rotations. For resembling different scenarios with respect to number of markers and of genotyped animals, a simulated data set divided into 25 subsets was used. Number of markers ranged from 1,200 to 5,925 and number of animals ranged from 1,200 to 5,865. Methods were also applied to real data comprising 3081 individuals genotyped for 45181 SNPs. Results from simulated data showed that the iterative solver was substantially faster than direct methods for larger numbers of markers. Use of a direct solver may allow for computing (co)variances of SNP effects. When applied to real data, performance of the iterative method varied substantially, depending on the level of ill-conditioning of the coefficient matrix. From results with real data, Gentleman-Givens rotations would be the method of choice in this particular application as it provided an exact solution within a fairly reasonable time frame (less than two hours). It would indeed be the preferred method whenever computer resources allow its use.
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The problem of multicollinearity in regression analysis was studied. Ridge regression (RR) techniques were used to estimate parameters affecting the performance of crossbred calves raised in tropical and subtropical regions by a model including additive, dominance, joint additive or "profit heterosis" and epistatic effects and their interactions with latitude in an attempt to model genotype by environment interactions. A software was developed in Fortran 77 to perform five variant types of RR: the originally proposed method; the method implemented by SAS; and three methods of weighting the RR parameter lambda. Three mathematical criteria were tested with the aim of choosing a value for the lambda coefficient: the sum and the harmonic mean of the absolute Student t-values and the value of lambda at which all variance inflation factors (VIF) became lower than 300. Prediction surfaces obtained from estimated coefficients were used to compare the five methods and three criteria. It was concluded that RR could be a good alternative to overcome multicollinearity problems. For all the methods tested, acceptable prediction surfaces could be obtained when the VIF criterion was employed. This mathematical criterion is thus recommended as an auxiliary tool for choosing lambda.
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Os autores analisaram, retrospectivamente, no período de 1977 a 1989, 793 cirurgias sobre a vesícula e vias biliares em um hospital universitário. Noventa e oito destes procedimentos foram realizados em pacientes acima de 60 anos. Avaliaram-se três grupos de cirurgias: colecistectomia (grupo I - 589 casos). colecistectomia com colangiografia pré-operatória(grupo II - 127 caso) e colecistectomia com exploraçäo de vias biliares (grupo III - 77 casos). Nos pacientes acima de 60 anos, obteve-se um índice de infecçäo de ferida 8.5 por cento (p<0,05),12.5 por cento (p<0,05) e 4,3 por cento (p>0,05 por cento), dos grupos I, II, III respectivamente. Concluem os autores que, da análise de sua casuística, o fator idade influenciou estatisticamente na incidência de infecçäo de ferida operatória nas colecistectomias simples, acompanhadas ou näo de colangiografia intra-operatória. Näo se observou valores estatisticamente significativos ao se relacionar a idade com o procedimento de exploraçäo de vias-biliares