Role of the DnaK-ClpB bichaperone system in DNA gyrase reactivation during a severe heat-shock response in Escherichia coli.

In Escherichia coli cells, an increase in temperature induces immediate DNA relaxation, followed by the fast recovery of DNA supercoiling. DNA gyrase, proteins synthesized during heat stress, and chaperone DnaK have been proposed to participate in this recovery. However, the mechanism of DNA supercoiling recovery has not been completely elucidated. The results presented here suggest that in cells exposed to severe heat-shock stress, DNA supercoiling levels are recovered by the reactivation of DNA gyrase. This reactivation involves solubilization of a fraction of protein GyrA present in protein aggregates, by the bichaperone DnaK-ClpB system.

Latin American consensus: children born small for gestational age.

BACKGROUND: Children born small for gestational age (SGA) experience higher rates of morbidity and mortality than those born appropriate for gestational age. In Latin America, identification and optimal management of children born SGA is a critical issue. Leading experts in pediatric endocrinology throughout Latin America established working groups in order to discuss key challenges regarding the evaluation and management of children born SGA and ultimately develop a consensus statement. DISCUSSION: SGA is defined as a birth weight and/or birth length greater than 2 standard deviations (SD) below the population reference mean for gestational age. SGA refers to body size and implies length-weight reference data in a geographical population whose ethnicity is known and specific to this group. Ideally, each country/region within Latin America should establish its own standards and make relevant updates. SGA children should be evaluated with standardized measures by trained personnel every 3 months during year 1 and every 6 months during year 2. Those without catch-up growth within the first 6 months of life need further evaluation, as do children whose weight is ≤ -2 SD at age 2 years. Growth hormone treatment can begin in SGA children > 2 years with short stature (< -2.0 SD) and a growth velocity < 25th percentile for their age, and should continue until final height (a growth velocity below 2 cm/year or a bone age of > 14 years for girls and > 16 years for boys) is reached. Blood glucose, thyroid function, HbA1c, and insulin-like growth factor-1 (IGF-1) should be monitored once a year. Monitoring insulin changes from baseline and surrogates of insulin sensitivity is essential. Reduced fetal growth followed by excessive postnatal catch-up in height, and particularly in weight, should be closely monitored. In both sexes, gonadal function should be monitored especially during puberty. SUMMARY: Children born SGA should be carefully followed by a multidisciplinary group that includes perinatologists, pediatricians, nutritionists, and pediatric endocrinologists since 10% to 15% will continue to have weight and height deficiency through development and may benefit from growth hormone treatment. Standards/guidelines should be developed on a country/region basis throughout Latin America.

Prevalence of dementia in older latinos: the influence of type 2 diabetes mellitus, stroke and genetic factors.

OBJECTIVES: To estimate dementia prevalence in older Mexican Americans, determine the distribution of dementia by etiology, and evaluate the contribution of type 2 diabetes mellitus, stroke, and apolipoprotein E (ApoE) genotype to dementia. DESIGN: Analysis of baseline data from an epidemiological cohort study. SETTING: Sacramento Valley, California. PARTICIPANTS: One thousand seven hundred eighty-nine Latinos aged 60 and older residing in targeted census tracts during 1998-99. MEASUREMENTS: Each subject was interviewed and screened for dementia and cardiovascular risk factors and diseases. Fasting blood samples were drawn for glucose, insulin, and lipids. Buccal cells were obtained for genetic analysis of ApoE. A three-stage process of screening was used to diagnose dementia, including cognitive testing, a clinical examination, and imaging to determine etiology. Presence of dementia was established according to National Institute of Neurological Disorders and Stroke/Alzheimers and Related Disorders Association criteria and California Alzheimer's Disease Diagnostic and Treatment Criteria. RESULTS: Overall dementia prevalence was 4.8%. Prevalence in those aged 85 and older was 31%. Education and Anglo cultural orientation was negatively associated with dementia risk. Risk of dementia was nearly eight times higher in those with both type 2 diabetes mellitus and stroke. Forty-three percent of dementia was attributable to type 2 diabetes mellitus, stroke, or a combination of the two. ApoE allele frequency was E2 5.9%, E3 90.1%, and E4 4%. Those with any E4 and 4-4 combinations had a higher risk for dementia than those with the E3-3 combination. CONCLUSIONS: Dementia prevalence in this ethnic group is similar to that reported in Canadian and European studies but lower than in Caribbean-Hispanics residing in the United States. The etiological fraction of dementia attributable to type 2 diabetes mellitus and stroke is substantial and points toward the need for intervention research and treatment with the goal of reducing neurological sequelae in groups with high prevalence of type 2 diabetes mellitus. The allele frequency of ApoE was similar to that in other published studies on Mexican Americans. The low frequency of the E4 allele may contribute to the difference in etiology of dementia in older Mexican Americans and older people of European background. Dementia in this ethnic group may be related to preventable causes, with a smaller genetic component than in Europeans.

Antidepressant class and dosing among older Mexican Americans: application of geropsychiatric treatment guidelines.

OBJECTIVE: The objective of this study was to characterize patterns and correlates of antidepressant drugs (AD) among older Mexican Americans (MAs). METHODS: This study consisted of a cross-sectional, community-based sample from Northern California. AD class and dosing label information were inventoried and compared with Expert Consensus Guidelines for geriatric depression pharmacotherapy. RESULTS: Overall, 7.1% had been prescribed an AD, but 4.9% were within starting dose ranges. Fewer ADs (3.9%) were consistent with Consensus class and dose guidelines. Depressive symptoms and diabetes were significant positive predictors of ADs. Recent immigrants had lower odds of AD prescriptions. CONCLUSIONS: AD prescriptions among older MAs are low. Omitting AD class and dosing information may overestimate pharmacotherapy for geriatric depression.

Reactive oxygen species generated by microbial NADPH oxidase NoxA regulate sexual development in Aspergillus nidulans.

NADPH oxidases (Nox) have been characterized as higher eukaryotic enzymes used deliberately to produce reactive oxygen species (ROS). The recent discovery of new functional members of the Nox family in plants and animals has led to the recognition of the increasing importance of ROS as signals involved in regulation of diverse cellular processes such as defence, growth and signalling. Here, we address the role of NADPH oxidase-generated ROS in the biology of the filamentous fungus Aspergillus nidulans. We characterize the noxA gene and show that it encodes a member of a novel NADPH oxidase subfamily ubiquitous in lower eukaryotes. Deletion of noxA specifically blocks differentiation of sexual fruit bodies (cleistothecia), without affecting hyphal growth or asexual development. Accordingly, the noxA gene is induced during sexual development, peaking at the time of cleistothecia differentiation and in parallel with the hülle cell-associated catalase peroxidase gene cpeA. This expression pattern is not dependent on transcription factors SteA and StuA, which are essential for cleistothecia formation. In contrast, noxA-dependent premature sexual development correlates with noxA derepression in DeltasakA null mutants, connecting stress MAPK signalling to the regulated production of ROS. Using a nitroblue tetrazolium (NBT) assay to detect superoxide, we found that hülle cells and cleistothecia initials produce superoxide in a process inhibited by NADPH oxidase inhibitor DPI and markedly reduced in DeltanoxA mutants. Furthermore, using H2DCFDA, we detected that H2O2 and possibly other ROS are generated in a NoxA-dependent fashion, mainly in the external walls from cleistothecia initials. The essential role of NoxA-generated ROS in A. nidulans sexual differentiation and the presence of one or two noxA homologues in all analysed filamentous fungi suggest that NADPH oxidase-generated ROS play important roles in fungal physiology and differentiation.

Eficacia del cloruro de cetilpiridinio y el triclosan como antiséptico de la cavidad bucal / Efficacy of cetylpyridinium chloride and triclosan as an antiseptic in the oral cavity

Tanto el cloruro de cetilpiridinio como el triclosan, se encuentran presentes en gran cantidad de formulaciones usadas en la higiene bucal por sus propiedades antisépticas, específicamente en los líquidos enjuagatorios o enjuagues bucales. El objetivo de este estudio fue evaluar la eficacia del cloruro de cetilpiridinio (colgate plax Overnight®) y el triclosán (colgate plax menta®) como antisépticos en la cavidad bucal. Se tomaron muestras mediante hisopado de la cavidad oral de 10 jóvenes antes y después de la utilización de ambos productos siguiendo las instrucciones de uso. Las muestras fueron leídas a la 1 hora, Se transportaron en medio de Stuart hasta la lectura microbiológica previo cultivo bacteriológico. Los recuentos microbiológicos se enfocaron a los grupos bacterianos aerobios y anaerobios. Como resultado de este estudio, se determinó que tanto el cloruro de cetilpiridinio y el triclosán presentaron diferencias estadísticamente significativas sobre los grupos bacterianos aerobios y anaerobios, presentando eficacia; así como fue significativamente distinto el recuento bacteriano antes y después del uso de los productos.

Hipotiroidismo autoinmune asociado a nefropatía por IgA

La nefropatía por IgA, cuya incidencia en la población pediátrica oscila entre 1.5 y 56.21 según reportes publicados en el sur de Europa, Australia y Japón, se reporta como primera causa de glomerulonefritis primaria en niños. La nefropatía por IgA puede ser primaria o secundaria, se diagnostica por demostración de IgA predominantemente mesangial o IgA codominante en el glomérulo sin evidencia de lupus eritematoso. La mayoría de los pacientes presenta hematuria macroscópica y el pronóstico depende de los marcadores genéticos y la severidad de la lesión histológica renal. A continuación presentamos el reporte de un caso de una paciente con evidencia de hipotiroidismo primario autoinmune y nefropatía por IgA.

Alcalosis metabólica hipokalémica

Se expone un caso de síndrome de Bartter en un lactante menor de dos meses de edad con antecedente prenatal de polihidramnios y parto pretérmino. Con historia de vómito, diarrea y estreñimiento ocasional, asociado con retardo pondoestatural. Este paciente presentó cuadro de bronconeumonía viral la cual evolucionó en forma tórpida con aumento del síndrome de dificultad respiratoria (SDR) y deterioro del estado general por lo cual hubo necesidad de trasladarlo a la unidad de cuidado intensivo de pediatría. Allí se corroboró la presencia de alcalosis metabólica hipokalémica e hipoclorémica con aumento de la excreción urinaria de K, Na y Cl y defecto en la habilidad de concentrar la orina. Aunado a esto se detectó hiperreninemia, poliuria y aldosterona elevada. La tensión arterial fue normal con un percentil menor de cinco para el peso y de 10 para la talla. Con base en todo lo anterior se pudo confirmar el diagnóstico de síndrome de Bartter

Hipotiroidismo primario como causa de pubertad precoz e hiperplasia hipofisiaria

La hiperplasia hipofisiaria originada por falla primaria de un órgano endocrino no es rara. Se han informado casos de hipotiroidismo primario en niños y adultos como etiología de hipertrofia de la hipófisis (1-8). En ocasiones se han observado casos de adenomas y microadenomas hipofisiarios causados por esta alteración, tanto en humanos como en animales de experimentación (2, 6, 9, 10); otras entidades en las cuales se ha documentado aumento del tamaño de la hipófisis incluyen falla gonadal primaria y en pacientes con adrenalectomía total (1, 5). Los primeros casos informados se remontan a 1851 (5); en 1960 Van Wyck y Grumbach describieron un síndrome en niños caracterizado por pubertad precoz, galactorrea, hipotiroidismo primario y aumento del tamaño de la silla turca (!!); a partir de este momento los informes en la literatura demuestran la asociación entre estos dos hallazgos, que pueden llevar a notables confusiones diagnósticas y terapéuticas, debido a las alteraciones endocrinológicas y neurológicas asociadas; un diagnóstico adecuado permitirá un tratamiento oportuno de acuerdo a la patología de base. Las principales alteraciones neurológicas asociadas se producen por compresión de la vía visual por la hiperplasia de la hipófisis, ocasionando desde cambios leves en los campos visuales, papiledema, hasta ceguera (2, 6). Nosotros describimos el caso de una niña con pubertad precoz, talla baja y aumento del tamaño de la hipófisis, demostrado por estudios neurorradiológicos, en quien disminuyó el tamaño hipofisiario luego del tratamiento de sustitución hormonal.

Desinfectantes en el consultorio odontológico: halógenos, aldehídos, fenólicos / Disinfectants in the dental office: halogens, aldehydes, phenolic

Lo agentes antimicrobianos son ampliamente usados en el consultorio odontológico. Estos antimicrobianos se desarrollan cada día más, para elegir el que realmente será de utilidad, sin dañar al equipo, instrumentales pero sobre todo para no lastimar al paciente, se los deben conocer y manejarlos correctamente. La intención de este trabajo es describir agentes antimicrobianos de acción no selectiva específicamente para ser usados como agentes de desinfección, especialmente los objetos inanimados y mencionando el posible uso como agentes antisépticos. Se describirán los agentes desinfectantes de conocida efectividad, por ellos se limitarán a escribir las familias de los halógenos, fenólicis y aldehídos, sustancias que en la actualidad, son de mayor reconocimiento como agentes antimicrobianos.