You may find it trivial to move up and down while walking, but this motion is a masterpiece of 4 cm shaped by 7 million years of marriage between smoothness and bounce. This vertical movement, first noticed by Aristotle and now tracked by satellites, is particularly beneficial for loading our muscles to perform a little work efficiently. A lesson on how optimization is a relative success story, and not perfection, is described here
Nerve tissues exhibit some of the highest oxygen consumption rates found in the body. Neuroglobin, a heme protein distantly related to hemoglobin, is thought to enhance the supply of oxygen to the neurons, the eye, and some endocrine tissues. Neuroglobin may promote neuronal survival under hypoxic conditions as they occur, for example, in stroke.
The mammalian, highly amiloride-sensitive epithelial sodium channel (ENaC) is member of the degenerin/ENaC superfamily of ion channels known to be implicated in sodium homeostasis, mechanosensation, and mechanoperception. A novel role for ENaC implicated in differentiation processes in skin reshapes our current view of this ancient transmembrane channel protein.
How do we smell? Our knowledge of how odor information from the environment is perceived has greatly advanced since the discovery of approximately 1,000 genes for odorant receptors in the mammalian genome. From the combination of molecular-genetic, electrophysiological, and optical imaging studies a better understanding of how we smell is emerging.
Previous research studies have established much information about single-gene diseases. However, other genes also influencing the outcome of a disease and genes involved in complex disease remain largely unknown. Here we report on recombinant congenic strains of mice, a powerful tool for genetic dissection of a complex trait.
The adhesion molecule intercellular adhesion molecule-1 (ICAM-1) is known to play a crucial role in lung inflammation such as endotoxin-induced injury. Although ICAM-1 has been characterized on endothelial cells, limited information is available regarding its expression in the epithelial compartment. The present review provides novel views on this aspect.
Major histocompatibility complex (MHC) class II deficiency is a primary immunodeficiency. Lentiviral vectors are used for gene therapy in a mouse model of this disease. In addition, by a direct genetic correction approach, a diagnostic test to determine which of the four MHC II genes is defective in new MHC II-deficiency patients has been optimized.
Proteoglycans are complex molecules composed of long, unbranched sugar chains attached to a protein core. In the mammalian central nervous system, they are a major component of the extracellular matrix and of the cellular surface. After a central nervous system injury, their expression in the lesion area changes strongly and contributes to the inhibition of axon regrowth and brain repair.
In a variety of organs, epithelial cells assemble into networks of cysts and tubules. Such structures can be reproduced in vitro. Here the importance of plasma membrane compartmentalization and forces that drive morphogenetic events during cystogenesis are discussed.
Aldosterone controls electrolyte balance by acting on the renal epithelium. However, there is strong evidence that vascular endothelium is another target for mineralocorticoids. Endothelial cells gain sensitivity to diuretics when exposed to aldosterone. Atomic force microscopy detects such phenomena. It is speculated that endothelium and kidney join forces in the regulation of body fluids.
Selectins are cell adhesion molecules mediating attachment of leukocytes to activated endothelium as well as the adhesion reaction of tumors during malignancy. Heparin, which is known to attenuate metastasis, is a potent blocker of selectins. Here, the role of selectins in metastasis and the potential of heparin to modulate malignancy are discussed.
Proteomics is a promising new tool for functional genomics. In addition to two-dimensional gel electrophoresis, other methods that are based on liquid chromatography and mass spectrometry are now available to study proteins. in this brief article, we review the strengths and limitations of the proteomic approaches currently available to the researcher, and we provide examples of how proteomics has been, and can in the future be, used to study the kidney.
Aldosterone elicits not only genomic effects with physiological consequences within hours or days but also elicits rapid nongenomic effects, such as activation of sodium transport in target cells, within seconds or minutes. Rapid aldosterone effects, which have also, been shown in several in vivo studies in humans (e.g., increase in peripheral vascular resistance and blood pressure), are of potential clinical importance.
Cell death is discriminated into two main forms: apoptosis and necrosis. In contrast to necrosis, apoptosis is a regulated, energy-dependent form of cell death leading to phagocytosis of cellular remnants by neighboring cells. Characteristic morphological features of these two forms of cell death will be discussed and correlated to underlying molecular mechanisms.
The key question is not why some patients have proteinuria but rather why not all people have it. In the present review, we will present an update on the glomerular barrier after the recent breakthroughs in podocyte biology. In particular, we will discuss the role of the endothelium, which seems to be a neglected part of the glomerular membrane.
Synapse elimination is a widespread developmental process in the peripheral and central nervous system that brings about refinement of neural connections through epigenetic mechanisms. Here we describe recent advances concerning the role of the pattern of motoneuronal firing, synchronous or asynchronous, in neuromuscular synapse elimination.
Rat muscle studies suggest competition between free fatty acids (FFA) and glucose for oxidation, resulting in glucose-6-phosphate accumulation. However, FFA decrease glucose-6-phosphate in human skeletal muscle, indicating direct inhibition of glucose transport/phosphorylation. This mechanism could redirect glucose from muscle to brain during fasting and explain the insulin resistance associated with high-lipid diets and obesity.
The sarcoplasmic reticulum (SR) and apposed regions of the sarcolemma passively trap Ca2+ entering the cell to limit the rise in cytoplasmic Ca2+ concentration without SR pump involvement. When "leaky," the SR facilitates Ca2+ entry to the cytoplasm. SR Ca2+ release via inositol 1,4,5-trisphosphate receptors (IP(3)Rs) propagates as calcium waves; IP(3)Rs alone account for wave propagation.
Coordinated behavior within arterioles is necessary for large resistance changes to occur and is reflected as a conduction of dilations/constrictions along arterioles. These responses arise from locally initiated hyper- or depolarizations that propagate via transmembrane channels formed by connexins (gap junctions). Mounting evidence indicates that gap-junctional communication contributes to the control of vascular tone.
Superoxide is known to affect vascular physiology in several ways and has also been recognized to contribute significantly to vascular physiopathology. Here we discuss the emerging role of superoxide as an essential signaling molecule in normal physiology.
