[Hantavirosis: clinical and epidemiological characteristics of pediatric patients in Chile]. / Hantavirosis: Caracterización clínica-epidemiológica de pacientes pediátricos en Chile.

BACKGROUND: The first cases of Hantavirus cardiopulmonary syndrome in children were described in the United States and represented 8% of the total reported cases; in Chile, the proportion of pediatric cases represents 15% of all national cases. AIM: To describe the epidemiology and clinical course of 82 children reported to the Chilean Ministry of Health up to 2007 and to characterize more extensively a subgroup of 24 children whose detailed clinical data were available. RESULTS: Forty patients were under 10 years old. Seventeen (17/82) of 82 cases (20.7%) presented in the context of a family cluster. Ninety eight percent of cases (80/82) occurred among individuals living in rural areas and 66% during summer months). The overall fatality rate was 36.6%. Fever (93%), respiratory distress (75%) and gastrointestinal symptoms (75%) were the most frequent symptoms encountered in the 28 children studied more extensively. Abnormal blood coagulation test were significantly associated with death while an increased hematocrit was associated with severe cases (hemodynamic unstability). CONCLUSION: An early diagnosis should favor early onset of aggressive treatment that could potentially save lives. Increasing knowledge on the clinical presentation of the disease in children should improve early clinical diagnosis among health care professionals.

Hantavirosis: Caracterización clínica-epidemiológica de pacientes pediátricos en Chile / Hantavirosis: Clinical and epidemiological characteristics of pediatric patients in Chile

Background: The first cases of Hantavirus cardiopulmonary syndrome in children were described in the United States and represented 8 percent of the total reported cases; in Chile, the proportion of pediatric cases represents 15 percent of all national cases. Aim: To describe the epidemiology and clinical course of 82 children reported to the Chilean Ministry of Health up to 2007 and to characterize more extensively a subgroup of 24 children whose detailed clinical data were available. Results: Forty patients were under 10 years old. Seventeen (17/82) of 82 cases (20.7 percent) presented in the context of a family cluster. Ninety eight percent of cases (80/82) occurred among individuals living in rural areas and 66 percent during summer months). The overall fatality rate was 36.6 percent. Fever (93 percent), respiratory distress (75 percent) and gastrointestinal symptoms (75 percent) were the most frequent symptoms encountered in the 28 children studied more extensively. Abnormal blood coagulation test were significantly associated with death while an increased hematocrit was associated with severe cases (hemodynamic unstability). Conclusion: An early diagnosis should favor early onset of aggressive treatment that could potentially save lives. Increasing knowledge on the clinical presentation of the disease in children should improve early clinical diagnosis among health care professionals.

Introducción: Los primeros casos del síndrome cardiopulmonar por hantavirus en población pediátrica fueron descritos en Estados Unidos de América y representaron 8 por cientoo de los casos comunicados; en Chile la frecuencia relativa en niños ha sido de 15 por ciento del total nacional. Objetivo: Describir la epidemiología y evolución clínica de 82 niños notificados al MTNSAL hasta el 2007 y caracterizar el comportamiento clínico en 24 de ellos de quienes se disponía de registro clínico detallado. Resultados: Cuarenta pacientes tenían bajo 10 años de edad, predominando envarones. Un quinto (17/82) estuvo asociado a conglomerados familiares. Noventay ocho por ciento (80/82) se presentaron en áreas rurales y 54 (66 por ciento) ocurrieron en el verano. La letalidad fue de 36,6 por ciento. Los síntomas más frecuentes fueron: fiebre (93 por ciento), dificultad respiratoria (75 por ciento) y síntomas gastrointestinales (75 por ciento). De los exámenes de laboratorio con significancia estadística, las pruebas de coagulación alteradas predicen fallecimiento y el hematocrito elevado está siempre presente en pacientes graves. Conclusión: El diagnóstico oportuno facilita el tratamiento intensivo precoz. La difusión de la presentación clínica infantil mejorará la sospecha diagnóstica en el personal de salud.

Influenza: reemergencia de una antigua enfermedad y el potencial riesgo de una nueva pandemia / Influenza: the reemergence of an ancient disease and its risk of pandemia

Influenza (FLU) es una enfermedad aguda, altamente transmisible, que evoluciona en brotes anuales. La diversidad de los reservorios naturales y la capacidad de reordenamiento genético del virus FLU A, hacen que el potencial de pandemia por una nueva cepa esté presente. Las medidas de prevención incluyen el uso de vacunas inactivadas, las que están indicadas en lactantes entre 6 a 24 meses de vida, pacientes con enfermedades cardíacas y pulmonares crónicas, pacientes inmunocomprometidos, adultos sobre 65 años de edad, personal de salud y mujeres embarazadas. La vacuna atenuada nasal tiene indicación restringida a los grupos de edad entre 5 y 49 años. La profilaxis con fármacos antivirales está indicada en brotes y contactos de pacientes con factores de riesgo. El manejo considera el uso de fármacos antivirales en los casos graves. Ante una eventual pandemia se deben reforzar las medidas de prevención y hacer un uso racional de antivirales, tanto en profilaxis como en tratamiento.

Aluminum fluoride affects the structure and functions of cell membranes.

No useful biological function for aluminum has been found. To the contrary, it might play an important role in several pathologies, which could be related to its interactions with cell membranes. On the other hand, fluoride is a normal component of body fluids, soft tissues, bones and teeth. Its sodium salt is frequently added to drinking water to prevent dental caries. However, large doses cause severe pathological alterations. In view of the toxicity of Al(3+) and F(-) ions, it was thought of interest to explore the damaging effects that AlF(3) might induce in cell membranes. With this aim, it was incubated with human erythrocytes, which were examined by phase contrast and scanning electron microscopy, and molecular models of biomembranes. The latter consisted of large unilamellar vesicles (LUV) of dimyristoylphosphatidylcholine (DMPC) and bilayers of DMPC and dimyristoylphosphatidylethanolamine (DMPE) which were studied by fluorescence spectroscopy and X-ray diffraction, respectively. In order to understand the effects of AlF(3) on ion transport (principally sodium and chloride) we used the isolated toad skin to which electrophysiological measurements were applied. It was found that AlF(3) altered the shape of erythrocytes inducing the formation of echinocytes. This effect was explained by X-ray diffraction which revealed that AlF(3) perturbed the structure of DMPC, class of lipids located in the outer monolayer of the erythrocyte membrane. This result was confirmed by fluorescence spectroscopy on DMPC LUV. The biphasic (stimulatory followed by inhibitory) effects on the isolated skin suggested changes in apical Cl(-) secretion and moderate ATPase inactivation.

Satisfaction related factors of attendants to a medical research meeting.

OBJECTIVE: To assess satisfaction of attendants to a National Meeting on Medical Research in relation with the scientific quality and level of discussion of the research work. MATERIAL AND METHODS: An anonymous self-applied questionnaire was handed out to gather opinions about the scientific quality, level of discussion of the research work, and overall satisfaction with the meeting. The studied population included 400 physicians, all of them authors or collaborators of the research work presented. RESULTS: The rate of response was 62% (n = 249). Two hundred and twenty-four approved the scientific quality (90%), and 203 were satisfied with the level of discussion of research (88%); 239 were satisfied with the meeting as a whole (96%). The factors associated with dissatisfaction regarding the quality of the scientific meeting were the masculine gender (OR = 2.7, CI 95% = 0.8-9.l, p = 0.06), having an M.Sc. or Ph.D. degree (OR = 2.3, CI 95% = 0.9-5.5, p = 0.03), and having attending prior meetings more than twice (OR = 5.0, CI 95% = 1.5-18.4, p = 0.001). CONCLUSIONS: Most of the attendants were satisfied with the scientific quality and discussions of the research work. The masculine gender, having an M.Sc. or Ph.D. degree, and prior assistance were the factors associated with dissatisfaction of the scientific quality of the Meeting.

Toxic effects of the fungicide benomyl on cell membranes.

This paper examines the toxicity of the fungicide benomyl towards cell membranes. Approaches to this aim were the study of its acute effects on the stimulatory response of a frog neuroepithelial synapse and on membrane models. The latter consisted of large unilamellar vesicles of dimyristoylphosphatidylcholine (DMPC) and phospholipid multilayers built-up of DMPC and dimyristoylphosphatidylethanolamine (DMPE). Results showed that benomyl at concentrations as low as 10 microM decreased the stimulatory response of the potential difference (PD) and the short-circuit current (SCC) of the frog sympathetic junction. It is concluded that benomyl caused a dose-dependent reduction in the response of a sympathetic junction of the frog to stimulation leading to Cl(-) channel perturbation. This finding might be explained from those obtained from fluorescence spectroscopy and X-ray diffraction studies on membrane models. In fact, similar (0.01-1.0 mM) concentrations induced structural perturbations in DMPC large unilamellar vesicles and multilayers, respectively. Although it is still premature to define the precise molecular mechanism of benomyl toxicity, the experimental results confirm the important role played by the phospholipid bilayers in the interaction of the pesticide with cell membranes.

Physical state of bulk and protein-associated lipid in nicotinic acetylcholine receptor-rich membrane studied by laurdan generalized polarization and fluorescence energy transfer.

The spectral properties of the fluorescent probe laurdan (6-dodecanoyl-2-dimethylaminonaphthalene) were exploited to learn about the physical state of the lipids in the nicotinic acetylcholine receptor (AChR)-rich membrane and compare them with those in reconstituted liposomes prepared from lipids extracted from the native membrane and those formed with synthetic phosphatidylcholines. In all cases redshifts of 50 to 60 nm were observed as a function of temperature in the spectral emission maximum of laurdan embedded in these membranes. The so-called generalized polarization of laurdan exhibited high values (0.6 at 5 degrees C) in AChR-rich membranes, diminishing by approximately 85% as temperature increased, but no phase transitions with a clear Tm were observed. A still unexploited property of laurdan, namely its ability to act as a fluorescence energy transfer acceptor from tryptophan emission, has been used to measure properties of the protein-vicinal lipid. Energy transfer from the protein in the AChR-rich membrane to laurdan molecules could be observed upon excitation at 290 nm. The efficiency of this process was approximately 55% for 1 microM laurdan. A minimum donor-acceptor distance r of 14 +/- 1 A could be calculated considering a distance 0 < H < 10 A for the separation of the planes containing donor and acceptor molecules, respectively. This value of r corresponds closely to the diameter of the first-shell protein-associated lipid. A value of approximately 1 was calculated for Kr, the apparent dissociation constant of laurdan, indicating no preferential affinity for the protein-associated probe, i.e., random distribution in the membrane. From the spectral characteristics of laurdan in the native AChR-rich membrane, differences in the structural and dynamic properties of water penetration in the protein-vicinal and bulk bilayer lipid regions can be deduced. We conclude that 1) the physical state of the bulk lipid in the native AChR-rich membrane is similar to that of the total lipids reconstituted in liposomes, exhibiting a decreasing polarity and an increased solvent dipolar relaxation at the hydrophilic/hydrophobic interface upon increasing the temperature; 2) the wavelength dependence of laurdan generalized polarization spectra indicates the presence of a single, ordered (from the point of view of molecular axis rotation)-liquid (from the point of view of lateral diffusion) lipid phase in the native AChR membrane; 3) laurdan molecules within energy transfer distance of the protein sense protein-associated lipid, which differs structurally and dynamically from the bulk bilayer lipid in terms of polarity and molecular motion and is associated with a lower degree of water penetration.

Two distinguishable fluorescent modes of 1-anilino-8-naphthalenesulfonate bound to human albumin.

We study the interaction of 1-anilino-8-naphthalenesulfonate (ANS) with human (HSA) and bovine serum albumin (BSA) by phase and modulation fluorescence spectroscopy. We determined that both HSA and BSA show one or two distinguishable fluorescent sites, depending of the ANS/serum albumin ratio. At above a 1∶1 ANS/HSA molar ratio, the steady-state emission spectra for ANS can be resolved in two components: component 1, emitting with a lifetime (τ1) of 16 ns and a λ1max of 478 nm, with a quantum yield (фf1) of 0.67, and component 2, with a lifetime (τ2) of 2-4 ns and a λ2max of 483 nm, with an average quantum yield (фf2) of about 0.11. Considering these findings, the binding analysis is fitted with a model of two independent sites. Site 1 has an association constantK as1=0.87×10(6)M(-1) and a capacity of 1.04 mol of ANS/mol of HSA, and site 2 aK as2=0.079×10(6)M(-1) and a capacity of 2.34 mol of ANS/mol of HSA. Analysis of fluorescence lifetime distributions shows that the rigidity of the fluorophore environment at site 1 changes when site 2 is occupied. These findings suggest an interconnection between the two sites and that ligands can stabilize the protein's globular structure. To assess the identity of the ANS binding sites we used diazepam as a marker of the site located at the IIIA HSA subdomain and aspirin as a marker of sites located at the IIIA and IIA HSA subdomains. Both ligands displace ANS only from site 1, suggesting that it corresponds to the binding site located at the IIIA sub-domain of the protein. We determined that theK as values for diazepam and aspirin are 0.113× 10(6) and 0.021×10(6) M (-1) respectively.

Conditions for growing Mycoplasma canadense and Mycoplasma verecundum in a serum-free medium.

Mycoplasma canadense and Mycoplasma verecundum were cultured in a serum-free medium containing bovine serum albumin, cholesterol, oleic acid, and palmitic acid in order to avoid the addition of horse serum. Growth was detected by measurement of A640 and by colony formation. The level of growth attained in this medium was less than that obtained in the horse serum-supplemented media, but colonies retained their distinctive morphology.