Studies on the Elastic Tissue of the Skin and Its Relation to the Maintenance of Tissue Tension and to Lymphatic Drainage

1. The histology of the elastic tissue in the skin is described. 2. A method is described for determining the elasticity of the shin after death. 3. The importance of the shin as a physical "elastic membrane," possessing a certain amount of tension, is discussed with relation to tissue tension and the extravascular circulation of fluid in the limbs. 4. A short account is given of the part played by the shin, by reason of its elasticity and its effect on tissue tension, in the development of oedema

Quantification of the Energetic and Microcirculatory Heterogeneity in the Renal System

Acute kidney injury (AKI) is a syndrome characterized by the rapid loss of kidney function and is typically diagnosed by an increase in blood-urea-nitrogen and serum creatinine, a decrease in the glomerular filtration rate (GFR), and a decrease in urine output. AKI can be brought on by a myriad of events: physical damage to the kidney, cardiac arrest, blood loss, toxicologic effects from pharmacological drug use, and in most cases seen, sepsis. These events introduce global and or local ischemic insult to the kidney, causing a decrease in renal functionality. Originally, global renal hypoperfusion was thought to be the culprit causing AKI. However, evidence is showing that AKI can occur in the absence of this, proved by the normal or even increased blood flow seen in sepsis-induced AKI. In fact, studies are finding similar results that show microcirculatory dysfunction, inflammation, and tubular oxidative stress are the driving physiological factors for sepsis-induced AKI. The development and use of intravital video microscopy (IVVM) allows \textit{in vivo} studies of biological systems to be conducted. The excitation and emission of Flourophores are used to visualize specific structures and interactions within a system, and provide the means for analysis. Visualization of renal system structure and dynamics have be captured using IVVM, specifically ATP generation activity seen in the tubular epithelial cells and the microvascular dysfunction of blood flow associated with sepsis-induced AKI. The work proposed here focuses on using these images to quantify and explain the heterogeneity seen in the microhemodynamics of the cortical peritubular capillaries as well as mitochondrial energetics of the renal system. The information learned regarding oxygen delivery and energy consumption can be used to further understand the physio/pathophysio-logical interactions of the renal system in states of health and AKI

Bones' adaptive response to mechanical loading is essentially linear between the low strains associated with disuse and the high strains associated with the lamellar/woven bone transition.

There is a widely held view that the relationship between mechanical loading history and adult bone mass/strength includes an adapted state or "lazy zone" where the bone mass/strength remains constant over a wide range of strain magnitudes. Evidence to support this theory is circumstantial. We investigated the possibility that the "lazy zone" is an artifact and that, across the range of normal strain experience, features of bone architecture associated with strength are linearly related in size to their strain experience. Skeletally mature female C57BL/6 mice were right sciatic neurectomized to minimize natural loading in their right tibiae. From the fifth day, these tibiae were subjected to a single period of external axial loading (40, 10-second rest interrupted cycles) on alternate days for 2 weeks, with a peak dynamic load magnitude ranging from 0 to 14 N (peak strain magnitude: 0-5000 µε) and a constant loading rate of 500 N/s (maximum strain rate: 75,000 µε/s). The left tibiae were used as internal controls. Multilevel regression analyses suggest no evidence of any discontinuity in the progression of the relationships between peak dynamic load and three-dimensional measures of bone mass/strength in both cortical and cancellous regions. These are essentially linear between the low-peak locomotor strains associated with disuse (∼300 µε) and the high-peak strains derived from artificial loading and associated with the lamellar/woven bone transition (∼5000 µε). The strain:response relationship and minimum effective strain are site-specific, probably related to differences in the mismatch in strain distribution between normal and artificial loading at the locations investigated