Relationship between the Rate of H+ Transport and Pathways of Glucose Metabolism by Turtle Urinary Bladder

The urinary bladder of the fresh-water turtle acidifies its contents by actively transporting H(+) ions across the luminal membrane. It is known that the H(+) transport system is dependent upon oxidative metabolism and the substrate glucose; however, the specific biochemical events resulting in H(+) translocation have not been identified.This study examines the relationship between active H(+) transport and a specific oxidative pathway of glucose metabolism, the pentose phosphate shunt. To investigate this relationship the metabolic and transport rates were simultaneously measured under several well-defined conditions. When H(+) transport was inhibited by either the application of an opposing pH gradient or by acetazolamide, glucose metabolism by the pentose phosphate shunt declined. Conversely, stimulation of H(+) transport by either imposing a more favorable pH gradient or by CO(2) addition resulted in an increase in pentose phosphate shunt metabolism. Glycolytic activity, in contrast, was invariant with the maneuvers which altered the rate of H(+) transport. Additional experiments localized pentose phosphate shunt enzyme activity to the mucosal fraction of the bladder which is the cell layer responsible for acid secretion. The finding that the rate of glucose metabolism by the pentose phosphate shunt is related to the rate of H(+) transport suggests but does not prove that the pentose phosphate shunt may be an important metabolic pathway for H(+) transport by the turtle urinary bladder.     

Ultrasound examination of the hand

Twenty-five surgically confirmed soft-tissue lesions of the hand were examined prospectively by real-time ultrasound. Use of sonography enabled a reliable diagnosis of the cystic or solid nature of soft-tissue lesions, an accurate estimation of the volume, and precise three-dimensional localization of the abnormality. Sonography also facilitated the location of foreign bodies. Assessment of anatomic relationships of these lesions to tendons and surrounding structures by real-time sonography during palpation, flexion, and/or extension also aided in the surgical approach.     

Fine-root production dominates response of a deciduous forest to atmospheric CO2 enrichment

Fine-root production and turnover are important regulators of the biogeochemical cycles of ecosystems and key components of their response to global change. We present a nearly continuous 6-year record of fine-root production and mortality from minirhizotron analysis of a closed-canopy, deciduous sweetgum forest in a free-air CO(2) enrichment experiment. Annual production of fine roots was more than doubled in plots with 550 ppm CO(2) compared with plots in ambient air. This response was the primary component of the sustained 22% increase in net primary productivity. Annual fine-root mortality matched annual production, and the mean residence time of roots was not altered by elevated CO(2), but peak fine-root standing crop in midsummer was significantly higher in CO(2)-enriched plots, especially deeper in the soil profile. The preferential allocation of additional carbon to fine roots, which have a fast turnover rate in this species, rather than to stemwood reduces the possibility of long-term enhancement by elevated CO(2) of carbon sequestration in biomass. However, sequestration of some of the fine-root carbon in soil pools is not precluded, and there may be other benefits to the tree from a seasonally larger and deeper fine-root system. Root-system dynamics can explain differences among ecosystems in their response to elevated atmospheric CO(2); hence, accurate assessments of carbon flux and storage in forests in a globally changing atmosphere must account for this unseen and difficult-to-measure component.     

Age, gender, and body mass index are associated with renal function after kidney donation

Renal function is thoroughly evaluated before live kidney donation. However, some donors experience impaired recovery of renal function after donation. Our aim was to assess estimated glomerular filtration rate (eGFR) and mean relative (%) increase in creatinine one yr after donor nephrectomy. The study was based on retrospective data from kidney donors during the period 1997-2009. Pre-operative and one-yr follow-up data were available for 721 of 1067 donors. Mean relative increase in creatinine and eGFR were stratified by gender, body mass index (BMI), and age at donation. At one yr post-donation, overweight (BMI > 5 kg/m(2) ) women 50 yr or older experienced the lowest eGFR of 49.6 ± 8.8 mL/min/1.73 m(2) . Men younger than 50 yr with normal weight (BMI < 25 kg/m(2) ) had the highest eGFR of 66.6 ± 10.4 mL/min/1.73 m(2) . Overweight men 50 yr or older had the highest relative increase in creatinine of 49.4% compared to pre-donation. Men under 50 yr with normal weight had the smallest increase in creatinine of 35.2%. In multivariate analysis, older age (p < 0.001), male gender (p < 0.001), and overweight (p = 0.01) were associated with relative increase in creatinine after donation. Potential donors should be offered counseling regarding overweight, as this is a modifiable risk factor.