969 research outputs found
Extracellular Mg2+ regulates the intracellular Na+ concentration in rat sublingual acini
AbstractThe intracellular free Na+ concentration ([Na+]i) increases during muscarinic stimulation in salivary acinar cells. The present study examined in rat sublingual acini the role of extracellular Mg2+ in the regulation of the stimulated [Na+]i increase using the fluorescent sodium indicator benzofuran isophthalate (SBFI). The muscarinic induced rise in [Na+]i was approximately 4-fold greater in the absence of extracellular Mg2+. When Na+ efflux was blocked by the Na+,K+-ATPase inhibitor ouabain, the stimulated [Na+]i increase was comparable to that seen in an Mg2+-free medium. Moreover, ouabain did not add further to the stimulated [Na+]i increase in an Mg2+-free medium suggesting that removal of extracellular Mg2+ may inhibit the Na+ pump. In agreement with this assumption, ouabain-sensitive Na+ efflux and rubidium uptake were reduced by extracellular Mg2+ depletion. Our results suggest that extracellular Mg2+ may regulate [Na+]i in sublingual salivary acinar cells by modulating Na+ pump activity
International trade: theory and evidence
This is a textbook (out of print and copyright reverted to authors) that design for a one-semester course in international trade theory at the advanced undergraduate or beginning graduate level. It systematically examines alternative causes of trade and the consequence of each. A much revised version is due to be published in 2011.International trade; gains from trade;
Identification of an alternative G{alpha}q-dependent chemokine receptor signal transduction pathway in dendritic cells and granulocytes
CD38 controls the chemotaxis of leukocytes to some, but not all, chemokines, suggesting that chemokine receptor signaling in leukocytes is more diverse than previously appreciated. To determine the basis for this signaling heterogeneity, we examined the chemokine receptors that signal in a CD38-dependent manner and identified a novel "alternative" chemokine receptor signaling pathway. Similar to the "classical" signaling pathway, the alternative chemokine receptor pathway is activated by G{alpha}i2-containing Gi proteins. However, unlike the classical pathway, the alternative pathway is also dependent on the Gq class of G proteins. We show that G{alpha}q-deficient neutrophils and dendritic cells (DCs) make defective calcium and chemotactic responses upon stimulation with N-formyl methionyl leucyl phenylalanine and CC chemokine ligand (CCL) 3 (neutrophils), or upon stimulation with CCL2, CCL19, CCL21, and CXC chemokine ligand (CXCL) 12 (DCs). In contrast, G{alpha}q-deficient T cell responses to CXCL12 and CCL19 remain intact. Thus, the alternative chemokine receptor pathway controls the migration of only a subset of cells. Regardless, the novel alternative chemokine receptor signaling pathway appears to be critically important for the initiation of inflammatory responses, as G{alpha}q is required for the migration of DCs from the skin to draining lymph nodes after fluorescein isothiocyanate sensitization and the emigration of monocytes from the bone marrow into inflamed skin after contact sensitization
Water pollutant fingerprinting tracks recent industrial transfer from coastal to inland China: a case study
In recent years, China’s developed regions have transferred industries to undeveloped regions. Large numbers of unlicensed or unregistered enterprises are widespread in these undeveloped regions and they are subject to minimal regulation. Current methods for tracing industrial transfers in these areas, based on
enterprise registration information or economic surveys, do not work. The authors have developed an analytical framework combining water fingerprinting and evolutionary analysis to trace the pollution transfer features between water sources. We collected samples in Eastern China (industrial export) and Central China
(industrial acceptance) separately from two water systems. Based on the water pollutant fingerprints and evolutionary trees, we traced the pollution transfer associated with industrial transfer between the two areas. The results are consistent with four episodes of industrial transfers over the past decade. The results also
show likely types of the transferred industries - electronics, plastics, and biomedicines - that contribute to the water pollution transfer
Effects of injection marination with various calcium sources and molar concentrations on display color life, tenderness, and microbial inhibition of beef loin steaks
Beef strip loins were assigned to one of
11 treatments that included injection
marination (10% by weight) with three
calcium salts at three molar concentrations,
a distilled water control, and a non-marinated
control. The effects of calcium
salt and concentration were tested for retail
display color life, tenderness and sensory
traits, and microbial growth. Calcium
lactate marinated steaks had longer color life
and less microbial growth than those treated
with calcium chloride or calcium ascorbate.
Increasing molar concentration (.1M to .2M to
.3M) caused faster color deterioration, and did
not significantly improve microbial inhibition.
All calcium treatments improved tenderness;
however, calcium chloride treatments induced
off-flavors. Considering a whole system
approach that accounts for color life, microbial
inhibition, shear force, and sensory traits, we
recommend injecting beef longissimus with
10% of a .1M solution of calcium lactate, and
do not recommend other calcium salts or
concentrations
The salivary gland fluid secretion mechanism
Fluid secretion by exocrine glands requires the coordinated activity of multiple water and ion transporter and channel proteins. The molecular cloning of many of the transporter molecules involved in fluid secretion has yielded a better understanding of the fluid secretion process. Mouse salivary glands are easily accessible model systems for the study of exocrine gland secretion at the cellular and organ level. Indeed, the characterization of mice with null mutations in many of the water and ion transporter and channel genes has demonstrated the physiological roles of individual proteins. This overview will focus on recent developments in determining the molecular identification of the proteins that are involved in the fluid secretion process
International trade: theory and evidence
This is a textbook (out of print and copyright reverted to authors) that design for a one-semester course in international trade theory at the advanced undergraduate or beginning graduate level. It systematically examines alternative causes of trade and the consequence of each. A much revised version is due to be published in 2011
Salivary Acinar Cells from Aquaporin 5-deficient Mice Have Decreased Membrane Water Permeability and Altered Cell Volume Regulation
Aquaporins (AQPs) are channel proteins that regulate the movement of water through the plasma membrane of secretory and absorptive cells in response to osmotic gradients. In the salivary gland, AQP5 is the major aquaporin expressed on the apical membrane of acinar cells. Previous studies have shown that the volume of saliva secreted by AQP5-deficient mice is decreased, indicating a role for AQP5 in saliva secretion; however, the mechanism by which AQP5 regulates water transport in salivary acinar cells remains to be determined. Here we show that the decreased salivary flow rate and increased tonicity of the saliva secreted byAqp5 − /− mice in response to pilocarpine stimulation are not caused by changes in whole body fluid homeostasis, indicated by similar blood gas and electrolyte concentrations in urine and blood in wild-type and AQP5-deficient mice. In contrast, the water permeability in parotid and sublingual acinar cells isolated from Aqp5 − /− mice is decreased significantly. Water permeability decreased by 65% in parotid and 77% in sublingual acinar cells fromAqp5 − /−mice in response to hypertonicity-induced cell shrinkage and hypotonicity-induced cell swelling. These data show that AQP5 is the major pathway for regulating the water permeability in acinar cells, a critical property of the plasma membrane which determines the flow rate and ionic composition of secreted saliva
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