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Biomedical subjects

K Hutcheson

Publications and source records attributed to K Hutcheson.

6 recordsLinked to original sources
PubMed2004

Epidemiological features of a newly described serotype of Shigella boydii.

We report the clinical, microbiological, and epidemiological features of an emerging serotype, Shigella boydii 20. We interviewed patients about symptoms, and history of travel and visitors during the week before illness onset. Seventy-five per cent of the 56 patients were Hispanic. During the week before illness onset, 18 (32%) travelled abroad; 17 (94%) had visited Mexico. Eight (21%) out of 38 who had not travelled had foreign visitors. There were eight closely related patterns by PFGE with XbaI. S. boydii 20 may be related to travel to Mexico and Hispanic ethnicity. Prompt epidemiological investigation of clusters of S. boydii 20 infection may help identify specific vehicles and risk factors for infection.

Adolescent↗
PubMed2003

p21 is essential for normal myogenic progenitor cell function in regenerating skeletal muscle.

Despite the ability of myogenic progenitor cells (MPCs) to completely regenerate skeletal muscle following injury, little is known regarding the molecular program that regulates their proliferation and differentiation. Although mice lacking the cyclin-dependent kinase inhibitor p21 (p21-/-), develop normally, we report here that p21-/- MPCs display increased cell number and enhanced cell cycle progression compared with wild-type MPCs. Therefore, we hypothesized that p21-/- mice would demonstrate temporally enhanced regeneration following myotrauma. In response to cardiotoxin-induced injury, p21-/- skeletal muscle regeneration was significantly attenuated vs. regenerating wild-type muscle, contrary to the hypothesis. Regenerating p21-/- skeletal muscle displayed increased proliferative (PCNA positive) nuclei coincident with increased apoptotic nuclei (TUNEL positive) compared with wild-type muscle up to 3 wk after injury. Differentiation of p21-/- MPCs was markedly impaired and associated with increased apoptosis compared with wild-type MPCs, confirming that the impaired differentiation of the p21-/- MPCs was a cell autonomous event. No dysregulation of p27, p53, or p57 protein expression in differentiating p21-/- MPCs compared with wild-type MPCs was observed, suggesting that other compensatory mechanisms are responsible for the regeneration that ultimately occurs. On the basis of these findings, we propose that p21 is essential for the coordination of cell cycle exit and differentiation in the adult MPC population and that in the absence of p21, skeletal muscle regeneration is markedly impaired.

Animals↗
PubMed2001

Adaptive mechanisms that preserve cardiac function in mice without myoglobin.

Mice lacking myoglobin survive to adulthood and meet the circulatory demands of exercise and pregnancy without cardiac decompensation. In the present study, we show that many myoglobin-deficient embryos die in utero at midgestation with signs of cardiac failure. Fetal mice that survive to gestational day 12.5, however, suffer no subsequent excess mortality. Survival in the absence of myoglobin is associated with increased vascularity and the induction of genes encoding the hypoxia-inducible transcription factors 1alpha and 2, stress proteins such as heat shock protein 27, and vascular endothelial growth factor. These adaptations are evident in late fetal life, persist into adulthood, and are sufficient to maintain normal myocardial oxygen consumption during stressed conditions. These data reveal that myoglobin is necessary to support cardiac function during development, but adaptive responses evoked in some animals can fully compensate for the defect in cellular oxygen transport resulting from the loss of myoglobin.

Adaptation, Physiological↗