Neuro-genetic plasticity of Caenorhabditis elegans behavioral thermal tolerance.

BACKGROUND: Animal responses to thermal stimuli involve intricate contributions of genetics, neurobiology and physiology, with temperature variation providing a pervasive environmental factor for natural selection. Thermal behavior thus exemplifies a dynamic trait that requires non-trivial phenotypic summaries to appropriately capture the trait in response to a changing environment. To characterize the deterministic and plastic components of thermal responses, we developed a novel micro-droplet assay of nematode behavior that permits information-dense summaries of dynamic behavioral phenotypes as reaction norms in response to increasing temperature (thermal tolerance curves, TTC). RESULTS: We found that C. elegans TTCs shift predictably with rearing conditions and developmental stage, with significant differences between distinct wildtype genetic backgrounds. Moreover, after screening TTCs for 58 C. elegans genetic mutant strains, we determined that genes affecting thermosensation, including cmk-1 and tax-4, potentially play important roles in the behavioral control of locomotion at high temperature, implicating neural decision-making in TTC shape rather than just generalized physiological limits. However, expression of the transient receptor potential ion channel TRPA-1 in the nervous system is not sufficient to rescue rearing-dependent plasticity in TTCs conferred by normal expression of this gene, indicating instead a role for intestinal signaling involving TRPA-1 in the adaptive plasticity of thermal performance. CONCLUSIONS: These results implicate nervous system and non-nervous system contributions to behavior, in addition to basic cellular physiology, as key mediators of evolutionary responses to selection from temperature variation in nature.

Anorexia y desnutrición en el adulto mayor / Anorexia and malnutrition in the elderly

El envejecimiento se asocia con un progresivo deterioro biológico y aumento de problemas de salud, resultantes de la interacción de factores genéticos y ambientales que incluyen estilos de vida, hábitos alimentarios, actividad física y presencia de enfermedades. La nutrición juega un papel muy importante en el envejecimiento a través de la modulación de cambios en diferentes órganos y funciones del organismo y asociados a este proceso. La anorexia fisiológica del envejecimiento también juega un papel importante en la pérdida de peso con la edad y hace a los gerontes muy vulnerables al desarrollo de la caquexia. Cualquier evaluación del estado nutricional se realizará con el objeto de entender la causa de posibles deficiencias, diseñar las intervenciones correctivas y evaluar su eficacia.

Ageing is associated with a progressive biological derangement and increase of health problems, as a result of the interaction of genetic and environmental factors that include life styles, alimentary habits, physical activity and presence of diseases. Nutrition plays an important role in the weight loss in the ageing through the modulation of changes in different organs and functions related to this process. The physiological anorexia of ageing plays an important role too in the weight loss in ageing and becomes the elderly very vulnerable to the development of cachexia. Any evaluation of the nutritional status will be carried out in order to understand the cause of possible deficiencies, to design corrective interventions and to evaluate its efficacy.

Tuberculosis among families of children with suspected tuberculosis and employees at a children's hospital.

Children with tuberculosis are rarely contagious, but their caregivers may be. Only 7 (12%) of 59 children were potentially contagious, and 10 (17%) were accompanied by contagious adults. Screening caregivers was more cost-effective than performing employee contact investigations, with one-sixteenth the cost ($5,470 vs $88,323) and requiring screening of 35 times fewer persons.

Tuberculosis among adult visitors of children with suspected tuberculosis and employees at a children's hospital.

OBJECTIVE: Few children with tuberculosis (TB) have communicable disease, and most do not require isolation within the hospital. However, parents or adult visitors with unrecognized pulmonary TB may be a threat to hospital staff and other patients. We prospectively evaluated adults accompanying children hospitalized for suspected TB at a children's hospital to determine the frequency of undiagnosed, potentially contagious disease. METHODS: From 1992 to 1998, chest radiographs were obtained from adult caretakers accompanying 59 consecutive children admitted to Texas Children's Hospital with suspected TB. A child and his or her family were placed under Airborne Precautions only if the child or the accompanying adult exhibited characteristics of potentially contagious disease. Annual rates of tuberculin skin test conversion in hospital employees were obtained for the same period. RESULTS: Of the 105 screened adults, 16 (15%) had previously undetected pulmonary TB. These adults were associated with 14 (24%) of the 59 children. In all instances in which the adult was the patient's parent, he or she was the source of infection to the child. Only 8 (13.5%) of the 59 children required isolation. Tuberculin skin test conversion from a negative to a positive reaction occurred in 127 employees (8 per 1,000 employee-years at risk). Only 4 of these 127 employees performed activities involving direct patient contact. None was in contact with families with a known potentially contagious adult or pediatric patient. CONCLUSIONS: The risk of infection of healthcare workers from pediatric patients with primary TB appeared to be minimal, and most children with TB did not need isolation. Infection control efforts should be focused on accompanying adults and adult visitors.