RESUMEN
Exposure to winter cold causes an increase in energy demands to meet the challenge of thermoregulation. In small rodents, this increase in cardiac output leads to a profound cardiac hypertrophy, 2-3x that typically seen with exercise training. The nature of this hypertrophy and its relevance to winter mortality remains unclear. Our goal was to characterize cold-induced cardiac hypertrophy and to assess its similarity to either exercise-induced (physiological) hypertrophy or the pathological hypertrophy of hypertension. We hypothesized that cold-induced hypertrophy will most closely resemble exercise-induced hypertrophy, but be another unique pathway for physiological cardiac growth. We found that cold-induced hypertrophy was largely reversed after return to warm temperatures. Further, metabolic rates were elevated while gene expression and mitochondrial enzyme activities indicative of pathology were absent. A gene expression panel comparing hearts of exercised and cold exposed mice further suggests that these activities are similar, although not identical. In conclusion, we found that chronic cold led to a phenotype that most closely resembled physiological hypertrophy, with enhanced metabolic rate, without induction of fetal genes , but with decreased expression of genes associated with fatty acid oxidation, suggesting that heart failure is not a cause of winter mortality in small rodents and identifying a novel approach for the study of cardiac growth.
RESUMEN
INTRODUCTION: Previous work has demonstrated a deficiency in urology resident education when it comes to andrology and male infertility. We analyzed the top 100 most frequently cited and influential articles published on testosterone deficiency and its associated therapy, allowing trainees and clinicians to review and understand the characteristics of impactful literature for self-directed learning purposes. METHODS: The ISI Web of Knowledge database was used to find articles on testosterone deficiency, hypogonadism, and replacement therapies. Relevant, peer-reviewed, English articles were included. Article details, including title, citation count, publication year, and more, were gathered. Articles were classified based on content (e.g. clinical outcomes, anatomy, and trends) using defined criteria. RESULTS: The top 300 most cited were reviewed with 100 included. The most cited article had 774 citations, averaging 234 in the top 100. Publication years had peaks in 2003-2004 and 2006-2007. The US led in publications (56), followed by England (16), Germany (14), and Italy (13). Common affiliations included US Department of Veteran Affairs, Veterans Health Administration, RIC Research Education Clinical Center, and University of California System. Articles were categorized as LOE 2 (47), LOE 1 (22), and LOE 5 (21). Articles focused on clinical outcomes (71.7%), anatomy/biomechanics/physiology (14.1%), clinical guidelines (8.1%), and screening (4%). The "Journal of Clinical Endocrinology & Metabolism" published 26 of the top 100 cited articles. CONCLUSIONS: This analysis highlights influential articles regarding testosterone deficiency and management. The discussed articles have significant clinical and therapeutic implications for the practicing urologist which may bolster deficits in current resident education.