ABSTRACT Gut microbiota plays an important role in animal health, production and diseases. Little is known about whether heat stress alters the composition of quail gut microbiota; therefore, we studied the effects of heat stress on growth performance, antioxidant functions, heat shock proteins and caecal microbiota. Two groups of 40 (20-day-old) quails were set up, including a control reared at 24 ± 2°C and a heat stress group subjected to heat stress at 36 ± 2°C for 4 h per day for 7 consecutive days. We found that heat stress significantly elevated the relative expression levels of HSP70 and HSP90 mRNA in the thymus, bursa and spleen by real-time fluorescence quantitative PCR assay, indicating successful establishment of the experimental model. Heat stress was found to have an effect on gut microbiota composition. At the genus level, Alistipes were significantly increased in the heat stress group. PICRUSt2 function prediction revealed that most of the KEGG pathways with high temperature-induced abundance differences are metabolism-related. These data indicated that heat stress reduced the production performance of quails by affecting antioxidant functions, as well as the composition and structure of the intestinal microbiota. The results of this study provide technical information for conducting research on heat stress prevention and control techniques in quails.

RESUMO Este estudo foi desenvolvido para avaliar a extensão da proteção contra a infecção pelo vírus da diarréia viral bovina tipo 2 (BVDV-2) através da vacinação com uma vacina combinada inativada contendo o vírus da diarréia viral bovina tipo 1 (BVDV-1) e vírus da rinotraqueíte de bovinos infecciosos (IBRV). Cinco bezerros com 3 a 4 meses de idade foram vacinados via intramuscular com uma dose única da vacina combinada e reforçados com a mesma dose três semanas após a primeira vacinação, com cinco bezerros imunizados em simulação servindo como grupo controle. Vinte e um dias após a segunda vacinação, todos os bezerros foram desafiados com a cepa BVDV-2 SX08 por spray na narina. Os animais não vacinados desenvolveram sinais clínicos típicos, como alta temperatura retal, diarréia com erosões e queda drástica na contagem de leucócitos. Estes sinais tiveram ocorrência significativamente menor em todos os animais vacinados, cuja temperatura retal, leucopenia e virarmia eram significativamente menores do que os bezerros simulados. É possível concluir que a vacinação com a vacina combinada inativada proporciona proteção cruzada contra os efeitos clínicos de uma infecção provocada pela cepa BVDV-2 SX08, embora tenha sido parcialmente protegida.

ABSTRACT This study was designed to evaluate the extent of the protection for bovine viral diarrhea virus type 2 (BVDV-2) infection, afforded by vaccination with a combo inactivated vaccine, which contains bovine viral diarrhea virus type 1 (BVDV-1) and infectious bovine rhinotracheitis virus (IBRV). Five 3-4-month-old calves were intramuscularly vaccinated with a single dose of the combo vaccine and boosted with same dose three weeks after the first vaccination, with five mock immunized calves serving as a control group. Twenty-one days after the second vaccination, all calves were challenged with BVDV-2 SX08 strain by spray into nostril. The unvaccinated animals developed typical clinical signs of high rectal temperature, diarrhoea with erosions and a dramatic drop in leukocyte counts. These signs occured markedly less in all vaccinated animals, the rectal temperature, leukopenia and virarmia of which, were significantly less than the mock immunized calves. It can be concluded that vaccination with the combo inactivated vaccine affords cross-protection against clinical effects of a challenge-infection with BVDV-2 SX08 strain, although it was part protection.

RESUMO: Solanum nigrum L. (erva-moura), uma planta daninha perene anual de curta duração, tornou-se uma planta daninha problemática em sistemas agrícolas na China central. Foram conduzidos experimentos em laboratório e em casa de vegetação para examinar a influência de vários fatores abióticos na germinação de sementes de erva-moura para o desenvolvimento de programas eficazes de controle de plantas daninhas. As sementes germinaram em temperaturas constantes de 15 a 30 oC, mas não ocorreu germinação em temperaturas abaixo de 10 oC ou acima de 35 oC. Também foi observada germinação das sementes em regimes de temperaturas alternadas de 15/5 oC a 40/30 oC, com germinação máxima (> 93,5%) nas temperaturas alternadas de 25/15 oC e 30/20 oC. Houve redução da germinação à medida que o potencial osmótico se tornou mais negativo, e nenhuma germinação foi observada a ≤ 0,8 MPa. Além disso, foi observada redução da germinação em função do estresse salino e alcalino, e nas concentrações ≥ 200 mM de NaCl ou ≥ 150 mM de NaHCO3 não ocorreu germinação. A germinação das sementes não foi afetada de forma significativa pelos valores de pH de 5 a 10, porém a emergência de plântulas sofreu influência significativa da profundidade de sementes, com emergência máxima (93,1%) a 1 cm de profundidade.

ABSTRACT: Solanum nigrum L. (black nightshade), an annual to short-lived perennial weed, has become a problem weed in farming systems in central China. Laboratory and greenhouse experiments were conducted to examine the influence of various abiotic factors on seed germination of black nightshade to develop effective weed control programs. Seeds germinated at a range of constant temperatures from 15 to 30 oC, but no germination occurred at temperatures below 10 oC or above 35 oC. Seeds also germinated at alternating temperature regimes from 15/5 to 40/30 oC, with maximum germination (> 93.5%) at the alternating temperatures of 25/15 and 30/20 oC. Germination decreased as osmotic potential became more negative, and no germination was observed at ≤ -0.8 MPa. Moreover, germination was reduced by saline and alkaline stresses and no germination occurred at ≥ 200 mM NaCl or ≥ 150 mM NaHCO3 concentrations. Seed germination was not significantly affected by pH values from 5 to 10. Seedling emergence was significantly affected by burial depth with maximum emergence (93.1%) at 1 cm depth.

This study aimed to test the effects of xuezhikang, a cholestin extract that contains statin-like components, on arterial stiffness in patients with essential hypertension. One hundred hypertensive patients from the Chinese PLA General Hospital were randomly allocated to receive xuezhikang (1200 mg/day, orally) or placebo (same capsules containing only pharmaceutical excipients). Physical examination outcomes, lipid profile, high sensitivity C-reactive protein (hs-CRP) levels, matrix metalloproteinases-9 (MMP-9) levels, and arterial outcomes, including stiffness parameter (β), pressure-strain elasticity modulus (Ep), arterial compliance (AC), augmentation index (AI), and one-point pulse wave velocity (PWVβ) were obtained at baseline and after 6 months of the intervention. Xuezhikang significantly reduced β (8.4±3.1 vs 6.8±2.1, P=0.007), Ep (122.8±43.9 vs 100.7±33.2, P=0.009), PWVβ (6.7±1.2 vs 6.1±1.0, P=0.013), low-density lipoprotein cholesterol (3.4±0.6 vs 2.9±0.5, P=0.001), hs-CRP [2.1 (0.4-10.0) vs 1.4 (0.3-4.1), P=0.020], and MMP-9 (17.2±2.4 vs 12.7±3.8, P <0.001) compared to baseline. The placebo had no effect on these parameters. The changes of PWVβ in the xuezhikang group was significantly associated with the changes of hs-CRP and MMP-9 (r=0.144, P=0.043; r=0.278, P=0.030, respectively) but not with lipid profile changes. Our research showed xuezhikang can improve the parameters of arterial stiffness in hypertensive patients, and its effect was independent of lipid lowering.

Several long non-coding RNA (lncRNA) might be correlated with the prognosis of colorectal cancer (CRC) and serve as a diagnostic and prognostic biomarker. However, the exact expression pattern of small nucleolar RNA host gene 12 (SNHG12) in colorectal cancer and its clinical significance remains unclear. The level of SNHG12 was detected by qRT-PCR in CRC tissues and CRC cells. MTT assay and colony formation assay were performed to examine the cell proliferation of CRC cells transfected with pcDNA-SNHG12 or si-SNHG12. Flow cytometry technology was used to detect cell cycle and cell apoptosis of CRC cells transfected with pcDNA-SNHG12 or si-SNHG12. The protein level of cell cycle progression-related molecules, including cyclin-dependent kinases (CDK4, CDK6), cyclin D1 (CCND1) and cell apoptosis-related molecule caspase 3 was detected by western blot. The effect of SNHG12 knockdown was examined in vivo. Increased levels of SNHG12 were observed in CRC tissues and in CRC cells. SNHG12 promoted the cell proliferation of CRC cells. In addition, SNHG12 overexpression boosted the cell cycle progression of SW480 cells transfected with pcDNA-SNHG12 and SNHG12 knockdown inhibited the cell cycle progression of HT29 cells transfected with si-SNHG12. SNHG12 also inhibited the cell apoptosis of CRC cells. We also found that SNHG12 increased the expression of cell cycle-related proteins and suppressed the expression of caspase 3. Our results suggest that SNHG12 promoted cell growth and inhibited cell apoptosis in CRC cells, indicating that SNHG12 might be a useful biomarker for colorectal cancer.

BACKGROUND: Atypical glandular cells (AGC) identified on Pap tests may be markers for potentially significant pathology. OBJECTIVES: Primarily, to correlate AGC findings at Groote Schuur Hospital (GSH), Cape Town, South Africa, with subsequent histological investigations and attempt to identify predictors of pathology relevant to the clinical management of women with a cytological diagnosis of AGC. Secondly, to compare the GSH data with data from similar international studies. METHODS: Records of AGC Pap tests were retrieved from the laboratory database in the anatomical pathology laboratory at GSH and clinically relevant information was summarised based on the available information. Standard descriptive statistics were used to summarise the study data, and Fisher's exact test was used to compare categorical outcomes, where possible. RESULTS: Of the 237 women with a cytological diagnosis of AGC and who had subsequent histological diagnoses, 120 (50.6%) had significant pathology (cervical intraepithelial neoplasia (CIN) 2 or worse). Significant cervical pathology was most common in women aged <50 years, while significant endometrial pathology predominated in women aged >50 years. The results of the GSH study were largely consistent with international findings, but the risk of malignancy was six times higher in the GSH population than in a comparable international group. CONCLUSION: AGC identified on Pap tests may be markers for potentially significant pathology. Human papillomavirus DNA testing is recommended for younger women diagnosed with AGC to reduce invasive investigations and minimise expenses in a resource-poor setting.

We aimed to describe the surgical technique and clinical outcomes of paraspinal-approach reduction and fixation (PARF) in a group of patients with Denis type B thoracolumbar burst fracture (TLBF) with neurological deficiencies. A total of 62 patients with Denis B TLBF with neurological deficiencies were included in this study between January 2009 and December 2011. Clinical evaluations including the Frankel scale, pain visual analog scale (VAS) and radiological assessment (CT scans for fragment reduction and X-ray for the Cobb angle, adjacent superior and inferior intervertebral disc height, and vertebral canal diameter) were performed preoperatively and at 3 days, 6 months, and 1 and 2 years postoperatively. All patients underwent successful PARF, and were followed-up for at least 2 years. Average surgical time, blood loss and incision length were recorded. The sagittal vertebral canal diameter was significantly enlarged. The canal stenosis index was also improved. Kyphosis was corrected and remained at 8.6±1.4o (P>0.05) 1 year postoperatively. Adjacent disc heights remained constant. Average Frankel grades were significantly improved at the end of follow-up. All 62 patients were neurologically assessed. Pain scores decreased at 6 months postoperatively, compared to before surgery (P<0.05). PARF provided excellent reduction for traumatic segmental kyphosis, and resulted in significant spinal canal clearance, which restored and maintained the vertebral body height of patients with Denis B TLBF with neurological deficits.

The monoamine serotonin (5-hydroxytryptamine, 5-HT), a well-known neurotransmitter, also has important functions outside the central nervous system. The objective of this study was to investigate the role of 5-HT in the proliferation, differentiation, and function of osteoblasts in vitro. We treated rat primary calvarial osteoblasts with various concentrations of 5-HT (1 nM to 10 µM) and assessed the rate of osteoblast proliferation, expression levels of osteoblast-specific proteins and genes, and the ability to form mineralized nodules. Next, we detected which 5-HT receptor subtypes were expressed in rat osteoblasts at different stages of osteoblast differentiation. We found that 5-HT could inhibit osteoblast proliferation, differentiation, and mineralization at low concentrations, but this inhibitory effect was mitigated at relatively high concentrations. Six of the 5-HT receptor subtypes (5-HT1A, 5-HT1B, 5-HT1D, 5-HT2A, 5-HT2B, and 5-HT2C) were found to exist in rat osteoblasts. Of these, 5-HT2A and 5-HT1Breceptors had the highest expression levels, at both early and late stages of differentiation. Our results indicated that 5-HT can regulate osteoblast proliferation and function in vitro.

Sirolimus, a potent inhibitor of B- and T-cell activation, is a commonly used immunosuppressant after renal transplantation. Withdrawal of sirolimus from the immunosuppression regimen may reduce B-cell surveillance. We present a case of rapidly progressive central nervous system (CNS) polymorphic Epstein-Barr virus (EBV)-related post-transplant lymphoproliferative disorder following the withdrawal of sirolimus

Primary squamous cell thyroid carcinoma (PSCTC) is a rare and aggressive tumor of uncertain origin. When squamous carcinoma is diagnosed, it is mandatory to exclude the possibility of primary tumor arising from an adjacent structure or representing metastases from a primary growth elsewhere. Aggressive surgical resection is the treatment of choice. However, the prognosis is poor, with a median survival of less than a year. Death is usually secondary to progression of local disease. We report a case of a patient presenting with a thyroid mass; biopsy was consistent with squamous cell carcinoma. On immunohistochemistry tumor cells were negative for TTF1, thyroglobulin and calcitonin. Cancer cells were positive for p63 and citok5. Extensive workup excluded the possibility of extrathyroid origin. The patient was treated with chemoradiotherapy; he died 9 months later due to local progression.

El carcinoma de células escamosas de tiroides (CCET) es un tumor infrecuente y agresivo. Su etiología es incierta. Ante la presencia de carcinoma escamoso en la glándula tiroides debe excluirse la posibilidad de infiltración de un tumor originado en una estructura adyacente o de metástasis de otros carcinomas. El tratamiento de elección es la cirugía radical. La mayoría de los pacientes fallecen antes del año debido a progresión local de la enfermedad. Presentamos el caso de un paciente con una masa tiroidea, con diagnóstico histológico de carcinoma escamoso (con inmunohistoquímca negativa para tiroglobulina, TTF1 y calcitonina y positiva para p63 y citok5). Los estudios clínicos, endoscópicos y radiológicos excluyeron otros sitios de origen de carcinoma escamoso. Fue tratado con quimio y radioterapia, falleciendo por progresión local luego de 9 meses.

Cytomegalovirus (CMV) is a frequent opportunistic infection in human inmunodeficiency virus type 1 (HIV-1) infected children associated with significant morbidity and mortality. The aim of this study was to determine the frequency and impact of CMV disease in a prospective ly followed cohort of HIV-1 infected Chilean children. CMV disease was diagnosed in 28 out of 222 HIV infected children (12.6%); 92% of them were classified in category C and 61% in category 3 (CDC, 1994). Lung disease was the most common manifestation (25 children). Samples were obtained from the respiratory tract, blood, urine and tissue biopsies. Shell vial for CMV early antigen detection was the most commonly used diagnostic technique (20/ 28). All patients were treated with iv.ganciclovir and two children died during the CMV episode. The mean survival time for the remaining children is currently 42 months. Conclusion: CMV disease was frequent and caused mortality in HIV-1 infected Chilean children. Early diagnosis and treatment are key for clinical success

Citomegalovirus (CMV) es una infección oportunista frecuente en niños infectados con el virus de la inmunodeficiencia humana tipo 1 (VIH 1) y produce altas tasas de morbilidad y mortalidad. El objetivo de este estudio fue determinar la frecuencia y trascendencia de la enfermedad por CMV en la cohorte de niños chilenos infectados con VIH-1. Se encontró enfermedad por CMV en 28 de 222 niños infectados con VIH-1 (12,6%o); 92%o fue clasificado en etapa C y 61%o en categoría 3 (CDC 1994). La enfermedad pulmonar fue la manifestación más común (25). Las muestras clínicas se obtuvieron de tracto respiratorio, sangre, orina y biopsia. Para la detección de CMV se utilizó, preferentemente, el cultivo acelerado (shell vial), (20/28). Todos fueron tratados con ganciclovir ev. El tiempo promedio de sobrevida fue 42 meses hasta el momento de esta evaluación. Conclusión: La enfermedad por CMV causó morbilidad y mortalidad en los niños chilenos infectados por VIH-1. El diagnóstico y tratamiento precoces son la base para un resultado exitoso

The identification of various risk factors of vertical human immunodeficiency virus (HIV) transmission resulted in the development of strategies whose aim was to decrease the mother's viral load, to reduce her child's exposure to it during delivery, and to avoid the subsequent viral exposure due to breastfeeding. The administration of antiretroviral treatment during pregnancy, delivery and to the neonate (PACTG 076) proved to be useful. At a first stage, zidovudine was used. A triple combination therapy was then administered. Initially, the viral transmission in mothers who were enrolled in protocols for vertically transmitted HIV prophylaxis was reduced to 9.5%, whereas the last measurement carried out between 1998 and 2005, the initial figure was brought down to 2%. Nevertheless, the delivery of infected children whose mother's HIV status was unknown is still considered likely to happen. The main step to be taken to reduce HIV infection among children is to perform universal HIV tests during pregnancy, so that HIV positive pregnant patients conveniently receive proper prophylaxis. We look forward to achieving this by following the new prevention guidelines of vertically-transmitted HIV infection, developed by the Comisión Nacional del SIDA of the Chilean Health Ministry

La identificación de diversos factores que inciden en el riesgo de la transmisión madre-hijo del virus de inmunodeficiencia humana (VIH), permitió diseñar estrategias dirigidas a disminuir su transmisión, entre ellas, medidas destinadas a disminuir la carga viral de la madre, disminuir la exposición del niño al VIH durante el parto y eliminar la exposición al mismo a través de la leche materna. Destaca la administración de anti-retrovirales durante el embarazo, parto y en el recién nacido, inicialmente, como protocolo PACTG 076 que utilizaba zidovudina y, posteriormente, el uso de trite-rapia. De esta manera, en las madres incorporadas en protocolos de profilaxis de transmisión vertical (TV) del VIH se logró reducir la transmisión de este virus, inicialmente, a 9,5% y en la última evaluación, realizada entre 1998 y julio 2005, a 2%. Sin embargo, han continuado naciendo niños infectados hijos de madres en las que no se conocía su condición serológica, lo que reafirma que la medida fundamental para disminuir los casos de infección por VIH en niños, es la pesquisa universal de la infección en las mujeres embarazadas, de manera que accedan en forma oportuna a protocolos de profilaxis, lo que se espera lograr con la nueva norma de prevención de TV del VIH, promulgada en agosto de 2005, por la Comisión Nacional del SIDA del Ministerio de Salud

This paper describes the increasing trends and changing patterns of human immunodeficiency virus (HIV) infection in children ocurring since 1982-83 when the first cases were reported worldwide and from 1987-89 when the first cases were detected in Chile. Advances and obstacles dealing with pediatric HIV in Chile are discussed. The most relevant advance is the outstanding reduction in vertical transmission of HIV associated with the implementation of preventive strategies. Risk of vertical transmission has decreased from 35%o in absence of preventive strategies to 2%o with prevention that include maternal and newborn antiretroviral therapy, elective caesarean section and replacement of breast feeding by artificial milk. The main obstacle to further reduce cases has been the delay in implementation of universal screening for pregnant women. This delay has resulted in that currently, the great majority of pediatric HIV cases are detected among symptomatic children. We propose a guideline to detect and appropriately derive pregnant women infected with HIV and children exposed or infected with the virus in order to further reduce the number of children with AIDS in Chile

Se describe el aumento y evolución que ha tenido, globalmente y en Chile, la infección por virus de inmunodeficiencia humana (VIH) en niños, desde los primeros casos detectados en 1982-83 en el mundo y en 1987-89 en Chile; también se describen los progresos y obstáculos que ha presentado el combate de esta entidad patológica en Chile. Entre los progresos destaca la disminución de la transmisión vertical del VIH con la aplicación de medidas para prevenirla, desde 35% en aquellos binomios madre-hijo en que no se adoptaron medidas preventivas, a 2% en aquellos que sí las recibieron (terapia antiretroviral, cesárea electiva, alimentación artificial al neonato y otras); entre los obstáculos, el principal ha sido el retraso en normar el ofrecimiento de el tamizaje para la infección por VIH a toda mujer embarazada. Por esta última razón, la mayoría de los niños infectados con VIH aún se siguen detectando en Chile en la vida postnatal, sobre la base de sus manifestaciones clínicas. Como una manera de ayudar a la prevención de la transmisión vertical del VIH y a la detección temprana de los niños infectados, se presenta un flujograma de pesquisa y derivación de las mujeres embarazadas infectadas y de los niños expuestos durante la gestación e infectados con el VTH

The objective of this paper is to review the history, epidemiology, aetiology, clinical presentation and management of SARS. SARS is a transmissible acute infectious disease produced by a corona virus totally new to humans (SARS-CoV). The disease appeared in China and from there disseminated in a few weeks to several areas of the world, causing thousands of cases and hundreds of deaths, with a total mortality of almost 10%. For this reason the WHO ordered the immediate notification of cases and the implementation of measures to contain or prevent the global, local and intra-hospital transmission. Initially the disease was epidemiological and clinical; appearence within 10 days of an epidemiological risk factor, close contact with a person with suspected or possible SARS, travel to an area affected, and clinically a flu-like disease with fever followed by a respiratory phase that can be complicated by severe respiratory failure. In this phase it is noteworthy the absence of pulmonary signs and florid radiographic changes. Leucopenia, lymphopenia, thrombocitopenia, elevation of LDH, creatine-kinase and alanine aminotransferase as well as diturbances in coagulation can be seen. The diagnosis of SARS-CoV is confirmed by RT-PCR and antibody detection. It´s management is empirical and consists in the use of anti-virals, oseltamivir, ribavirin and steroids, with varying results. Commentary: SARS is a severe disease that has given the worlds population several lessons and losses.

El objetivo de este artículo es revisar la historia y resaltar la epidemiología, etiología, presentación clínica y manejo del Síndrome Respiratorio Agudo Severo (SARS). El SARS es una enfermedad infecciosa aguda transmisible producida por un agente totalmente nuevo para el ser humano, un coronavirus (SARS-CoV). Iniciada en China, se ha diseminado en pocas semanas a varios otros países del mundo con miles de casos y cientos de muertes, con una letalidad global de casi el 10%. Por ello, la OMS ha declarado a esta enfermedad como de notificación inmediata a dicho organismo y ha instaurado una serie de medidas para contener/evitar su diseminación global y a nivel hospitalario y extra-hospitalario. El diagnóstico de esta enfermedad inicialmente es epidemiológico y clínico: aparición dentro de 10 días del antecedente epidemiológico (contacto estrecho con una persona sospechosa o con probable SARS; viaje a un área con transmisión reciente o actual de SARS) de un cuadro con una fase febril inicial, semejante a un cuadro gripal, y una fase respiratoria posterior, que puede llevar a insuficiencia respiratoria severa; en esta fase destaca lo pobre del examen físico pulmonar en contraste con la gran cantidad de imágenes radiológicas; otros hallazgos son leucopenia con linfopenia y disminución de plaquetas; aumento de dehidrogenasa láctica, creatinfosfoquinasa y alanino-aminotransferasa, y algunas alteraciones de la coagulación. El diagnóstico de infección por SARS-CoV puede ser confirmado con RT-PCR y detección de anticuerpos. El manejo, empírico, ha contemplado antivirales (oseltamivir, ribavirina) y corticoides, con respuestas variables. Comentarios: el SARS ha sido una enfermedad severa, pero que ha dejado muchas enseñanzas , y también pérdidas, a nivel mundial.

Background: Human immunodeficiency virus (HIV) epidemiology has changed, affecting an increasing number of children. As in adults, the disease predominantly affects the digestive and respiratory systems. Aim: To report the gastrointestinal problems in HIV infected pediatric patients. Patients and methods: Twenty four HIV infected children (nine male, aged 1 to 12 years old, followed for 1 to 170 months), are reported. This group has been under care by a multiprofessional team. Results: Oral candidiasis was present in 21 (88%), esophagic candidiasis in 3 (13%), oral ulcers in 4 (17%). Diarrhea was observed in 18 children (75%) and in eight, it had a chronic evolution. Cryptosporidium parvum was the most frequent agent found in six cases (1 with acute and 5 with chronic diarrhea). Schlerosing cholangiopathy was observed in one case, with a fatal outcome, in association to microsporidiosis. Upper endoscopy was done in 11 patients, demonstrating microscopic inflammatory changes in esophagic, gastric and duodenal epithelia in all. Conclusions: Digestive problems are common in HIV infected pediatric patients. They must be always sought actively. Endoscopy is a valuable tool for the early diagnosis of these problems (Rev Méd Chile 2003; 131: 19-24)