Minoxidil reduces pulmonary vascular resistance in dogs and cattle

Minoxidil has a direct dilator effect on the systemic arterial smooth muscle. It is potentially an important drug in the treatment of systemic hypertension, especially when combined with beta blockade, which is used to control the associated tachycardia and increase in cardiac output. However, recent observations have suggested that minoxidil might cause pulmonary hypertension. Consequently, we examined the acute effect of monoxidil and propranolol, separately and in combination, on the pulmonary vasculature of the anesthetized dog and the awake calf during normoxia and hypoxia. In both species minoxidil reduced pulmonary vascular resistance. In the dogs this appeared to be the result of a direct action on the pulmonary vascular smooth muscle and in the cattle it was secondary to beta-receptor stimulation. Propranolol alone in the cattle increased the pulmonary pressor response to hypoxia. While we have not examined the possibility that chronic administration of minoxidil might cause pulmonary hypertension by some other mechanism, our acute studies suggest that it reduces, rather than increases, pulmonary vascular resistance. Furthermore, there seems to be a species difference in the mode of its action in dogs and cattle.     

Social networks as assets and liabilities in recovery from stroke by geriatric patients.

Interactions in the social networks of 48 elderly stroke patients were examined as factors influencing outcomes after hospital discharge. Structured interviews assessed the frequency of perceived positive and negative interactions, as well as patients' behavioral independence, time use, personal adjustment, and cognitive functioning. Negative interactions occurred less frequently than positive ones. After controlling for status at hospital discharge, negative and positive interactions differentially explained variance in morale, psychiatric symptoms, and cognitive functioning. Although negative interactions were associated with poorer morale and greater psychiatric symptoms, positive interactions were associated with less mental confusion. Patients' reporting and not reporting negative interactions did not differ significantly on a variety of social and demographic variables previously shown to predict social interactions and well-being. Findings indicate that social interactions may both impede and facilitate rehabilitation for older adults and have implications for both theories of social support and the design of therapeutic interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The spatial arrangement of tubules in human dentin

We applied two-dimensional numerical methods to describe the spatial arrangement of tubules in human dentin. The methods considered were two-point correlation functions, entropy-like measures, and angular distributions between nearest neighbors. The correlation functions were based on Fourier transform methods. The latter two approaches were based on stochastic geometry, and involved developing the Delaunay tessellations of the tubule patterns and their dual Voronoi diagrams. We discovered that for analyzing the distribution of tubules the geometric methods of lattice tessellations were more sensitive to structural order of the tubules than were Fourier-based schemes. Analysis of the data indicated that dentinal tubules are highly ordered in normal dentin. © 2001 Kluwer Academic Publishers     

Elevated airborne exposures of teenagers to manganese, chromium, and iron from steel dust and New York City's subway system

There is increasing interest in potential health effects of airborne exposures to hazardous air pollutants at relatively low levels. This study focuses on sources, levels, and exposure pathways of manganese, chromium, and iron among inner-city high school students in New York City (NYC) and the contribution of subways. Samples of fine particulate matter (PM2.5) were collected during winter and summer over 48 h periods in a variety of settings including inside homes, outdoors, and personal samples (i.e., sampling packs carried by subjects). PM2.5 samples were also collected in the NYC subway system. For NYC, personal samples had significantly higher concentrations of iron, manganese, and chromium than did home indoor and ambient samples. The ratios and strong correlations between pairs of elements suggested steel dust as the source of these metals for a large subset of the personal samples. Time-activity data suggested NYC subways as a likely source of these elevated personal metals. In duplicate PM2.5 samples that integrated 8 h of underground subway exposure, iron, manganese, and chromium levels (>2 orders of magnitude above ambient levels) and their ratios were consistent with the elevated personal exposures. Steel dust in the NYC subway system was the dominant source of airborne exposures to iron, manganese, and chromium for many young people enrolled in this study, with the same results expected for other NYC subway riders who do not have occupational exposures to these metals. However, there are currently no known health effects at the exposure levels observed in this study.     

Genetic Encoding of a Photocaged Histidine for Light-Control of Protein Activity

The use of light to control protein function is a critical tool in chemical biology. Here we describe the addition of a photocaged histidine to the genetic code. This unnatural amino acid becomes histidine upon exposure to light and allows for the optical control of enzymes that utilize active-site histidine residues. We demonstrate light-induced activation of a blue fluorescent protein and a chloramphenicol transferase. Further, we genetically encoded photocaged histidine in mammalian cells. We then used this approach in live cells for optical control of firefly luciferase and, Renilla luciferase. This tool should have utility in manipulating and controlling a wide range of biological processes.