Spaceflight-induced alterations in cerebral artery vasoconstrictor, mechanical, and structural properties: implications for elevated cerebral perfusion and intracranial pressure.

Evidence indicates that cerebral blood flow is both increased and diminished in astronauts on return to Earth. Data from ground-based animal models simulating the effects of microgravity have shown that decrements in cerebral perfusion are associated with enhanced vasoconstriction and structural remodeling of cerebral arteries. Based on these results, the purpose of this study was to test the hypothesis that 13 d of spaceflight [Space Transportation System (STS)-135 shuttle mission] enhances myogenic vasoconstriction, increases medial wall thickness, and elicits no change in the mechanical properties of mouse cerebral arteries.

Stochastic ontogenetic allometry: the statistical dynamics of relative growth.

Background: In the absence of stochasticity, allometric growth throughout ontogeny is axiomatically described by the logarithm-transformed power-law model, θt = log(a) b + kφ(t), where θt ≡ θ(t) and φt ≡ φ(t) are the logarithmic sizes of two traits at any given time t. Realistically, however, stochasticity is an inherent property of ontogenetic allometry. Due to the inherent stochasticity in both θt and φt, the ontogenetic allometry coefficients, log(a) b and k, can vary with t and have intricate temporal distributions that are governed by the central and mixed moments of the random ontogenetic growth functions, θt and φt.

Evolution with stochastic fitness and stochastic migration.

Background: Migration between local populations plays an important role in evolution - influencing local adaptation, speciation, extinction, and the maintenance of genetic variation. Like other evolutionary mechanisms, migration is a stochastic process, involving both random and deterministic elements. Many models of evolution have incorporated migration, but these have all been based on simplifying assumptions, such as low migration rate, weak selection, or large population size.

Hydrodynamics-based functional forms of activity metabolism: a case for the power-law polynomial function in animal swimming energetics.

The first-degree power-law polynomial function is frequently used to describe activity metabolism for steady swimming animals. This function has been used in hydrodynamics-based metabolic studies to evaluate important parameters of energetic costs, such as the standard metabolic rate and the drag power indices. In theory, however, the power-law polynomial function of any degree greater than one can be used to describe activity metabolism for steady swimming animals.

99mTechnetium-ciprofloxacin scintigraphy for the evaluation of spinal infections: a preliminary report.

Unlabelled: Currently available laboratory and imaging tests have limitations diagnosing and following patients with spinal infections. We evaluated 17 Technetium-99m labeled ciprofloxacin scintigraphy studies in 11 patients who had the diagnosis of a spinal infection based on the Centers for Disease Control and Prevention criteria. Three of the 17 studies were performed in three patients within 2 months from the onset of the symptoms.

Effects of hindlimb unweighting on the mechanical and structure properties of the rat abdominal aorta.

Previous studies have shown that hindlimb unweighting of rats, a model of microgravity, reduces evoked contractile tension of peripheral conduit arteries. It has been hypothesized that this diminished contractile tension is the result of alterations in the mechanical properties of these arteries (e.g.

Extragenital bowenoid papulosis associated with atypical human papillomavirus genotypes.

Background: Bowenoid papulosis typically appears as grouped violaceous or red-brown papules in the genital or perianal regions and clinically resembles condylomata acuminata. Isolated extragenital bowenoid papulosis is rare and has been reported in only a few case reports.

Objectives: A 51-year-old immunocompetent, healthy woman had two solitary papules on the elbow; a 41-year-old HIV-positive man had a solitary cutaneous plaque on the abdomen.

Effects of aging on vasoconstrictor and mechanical properties of rat skeletal muscle arterioles.

Exercise capacity and skeletal muscle blood flow during exercise are reduced with advancing age. This reduction in blood flow capacity may be related to increased reactivity of skeletal muscle resistance vessels to vasoconstrictor stimuli. The purpose of this study was to test the hypothesis that aging results in increased vasoconstrictor responses of skeletal muscle resistance arterioles.