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Regulating Mechanisms (regulating + mechanism)

Distribution by Scientific Domains
Medical Sciences50%
Life Sciences50%

Selected Abstracts

Relationship between ocular pulse amplitude and systemic blood pressure measurements

ACTA OPHTHALMOLOGICA, Issue 3 2009
Matthias C. Grieshaber
Abstract. Purpose:, This study aimed to determine whether ocular pulse amplitude (OPA) measured with dynamic contour tonometry (DCT) is related to systemic blood pressure (BP) parameters. Methods:, Blood pressure was measured continuously and simultaneously with OPA in one randomly selected eye in 29 healthy subjects. Systemic parameters of interest were: systolic and diastolic BPs and their difference (BP amplitude), and left ventricle ejection time (LVET; defined as the time between the diastolic trough and the incisural notch in the BP curve). In addition, the axial length (AL) of the eye was measured. Associations between OPA, AL and systemic cardiovascular parameters were analysed in a multivariate regression model. Results:, Measurements of OPA ranged from 1.0 mmHg to 4.9 mmHg (mean 2.3 ± 0.9 mmHg, median 1.9 mmHg). In a univariate analysis with one predictor at a time, means of intraocular pressure (IOP) (p = 0.008), AL (p = 0.046) and LVET (p = 0.037) were significantly correlated with OPA, whereas systolic and diastolic BPs and their amplitude were not. A multiple linear regression analysis showed that mean IOP (p < 0.005), AL (p = 0.01) and LVET (p = 0.002) all independently contributed to OPA. Conclusions:, The OPA readings measured with DCT in healthy subjects were not related to BP levels and amplitude. It seems that the OPA strongly depends on the time,course of the cardiac contraction. Regulating mechanisms in the carotid system as well as scleral rigidity may be responsible for dampening the direct effect of BP variations. [source]

Field contamination of the starfish Asterias rubens by metals.

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003
Part 1: Short-, long-term accumulation along a pollution gradient
Abstract The accumulation of Cd, Pb, Zn, and Cu in the starfish Asterias rubens was studied in a Norwegian fjord characterized by a gradient of metal pollution in the sediments, ranging from very high metal concentrations at its head to much lower levels at its opening. The concentrations of metals in starfish from natural populations along the gradient (long-term accumulation) and in starfish that were transferred up the gradient (short-term accumulation) were compared. At long-term, Cd and Pb accumulations by starfish living at normal salinity (30,) were related to the level of contamination of of the environment while Cu and, to a lesser extent, Zn accumulations appeared strictly controlled. At short-term, Pb was accumulated steadily, Cd and Zn were accumulated transiently in the pyloric caeca (fast compartment), and Cu was not accumulated at all. Depuration experiments (transfer down the gradient) showed that Cd and Pb were efficiently eliminated from the pyloric caeca but not from the body wall (slow compartment). It is concluded that Pb is chronically accumulated, without apparent control, Cd is subjected to a regulating mechanism in the pyloric caeca which is overwhelmed over the long-term; Zn is tightly controlled in the pyloric caeca and Cu in both pyloric caeca and body wall. A distinct color variety of starfish is restricted to the low salinity (22-26,) superficial water layer. This variety showed a different pattern of metal accumulation over the long-term. This pattern is attributed to the particular hydrological conditions prevailing in this upper layer. [source]

Fibroblast response to interstitial flow: A state-of-the-art review

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010
Liu Dan
Abstract Interstitial flow (IF) modulates both the biochemical and biophysical cues surrounding cells. It represents a very important regulating mechanism for cell/tissue function and has been commonly utilized in tissue engineering (TE). This article discusses the possible regulating mechanisms of IF on fibroblasts, the various fibroblast responses to IF, the current challenges in understanding the IF,fibroblast relationship and the application of IF for fibroblast involved TE. In particular, IF can affect fibroblast growth at both intracellular (e.g., calcium signaling, protein/proteinase secretion) and cellular (e.g., autocrine/paracrine signaling, proliferation, differentiation, alignment, adhesion, migration) levels. One major challenge for understanding IF,fibroblast interaction has been the determination of the flow and cell growth condition at microlevel especially in a three-dimensional environment. To utilize IF and optimize the fluidic environment for TE, several influencing factors in the system including perfusate composition, flow profile, nutrient supply, signaling molecule effect, scaffold property, and fibroblast type should be considered. Biotechnol. Bioeng. 2010;107: 1,10. © 2010 Wiley Periodicals, Inc. [source]

Chronic inflammation in asthma: a contest of persistence vs resolution

ALLERGY, Issue 9 2008
C. L. Van Hove
Recent investigations have highlighted that endogenous anti-inflammatory mediators and immune regulating mechanisms are important for the resolution of inflammatory processes. A disruption of these mechanisms can be causally related not only to the initiation of unnecessary inflammation, but also to the persistence of several chronic inflammatory diseases. In asthma, chronic Th-2 driven eosinophilic inflammation of the airways is one of the central abnormalities. To date, elucidating the role of the different pro-inflammatory mediators involved in orchestrating the inflammatory processes in asthma has been the subject of intense research in both humans and animal models. However, the counter-regulatory mechanisms that co-determine the outcome in the contest of resolution vs persistence of the eosinophilic airway inflammation remain poorly understood. These are currently being investigated in animal models of chronic asthma. Elucidating these mechanisms is of relevance, since it can give rise to a new therapeutic approach in the treatment of chronic airway inflammation in asthmatics. This novel concept of treatment involves the stimulation of endogenous anti-inflammatory pathways, rather than solely antagonising the various pro-inflammatory mediators. Here, we review and discuss the current knowledge about these endogenous anti-inflammatory mediators in clinical and experimental asthma. [source]

Fibroblast response to interstitial flow: A state-of-the-art review

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010
Liu Dan
Abstract Interstitial flow (IF) modulates both the biochemical and biophysical cues surrounding cells. It represents a very important regulating mechanism for cell/tissue function and has been commonly utilized in tissue engineering (TE). This article discusses the possible regulating mechanisms of IF on fibroblasts, the various fibroblast responses to IF, the current challenges in understanding the IF,fibroblast relationship and the application of IF for fibroblast involved TE. In particular, IF can affect fibroblast growth at both intracellular (e.g., calcium signaling, protein/proteinase secretion) and cellular (e.g., autocrine/paracrine signaling, proliferation, differentiation, alignment, adhesion, migration) levels. One major challenge for understanding IF,fibroblast interaction has been the determination of the flow and cell growth condition at microlevel especially in a three-dimensional environment. To utilize IF and optimize the fluidic environment for TE, several influencing factors in the system including perfusate composition, flow profile, nutrient supply, signaling molecule effect, scaffold property, and fibroblast type should be considered. Biotechnol. Bioeng. 2010;107: 1,10. © 2010 Wiley Periodicals, Inc. [source]

Multidrug resistance-associated proteins and implications in drug development

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1 2010
Ya-He Liu
Summary 1.,The multidrug resistance-associated proteins (MRPs) belong to the ATP-binding cassette superfamily (ABCC family) of transporters that are expressed differentially in the liver, kidney, intestine and blood,brain barrier. There are nine human MRPs that transport a structurally diverse array of endo- and xenobiotics as well as their conjugates. 2.,Multidrug resistance-associated protein 1 can be distinguished from MRP2 and MRP3 by its higher affinity for leukotriene C4. Unlike MRP1, MRP2 functions in the extrusion of endogenous organic anions, such as bilirubin glucuronide and certain anticancer agents. In addition to the transport of glutathione and glucuronate conjugates, MRP3 has the additional capability of mediating the transport of monoanionic bile acids. 3.,Both MRP4 and MRP5 are able to mediate the transport of cyclic nucleotides and confer resistance to certain antiviral and anticancer nucleotide analogues. Hereditary deficiency of MRP6 results in pseudoxanthoma elasticum. In the body, MRP6 is involved in the transport of glutathione conjugates and the cyclic pentapeptide BQ123. 4.,Various MRPs show considerable differences in tissue distribution, substrate specificity and proposed physiological function. These proteins play a role in drug disposition and excretion and thus are implicated in drug toxicity and drug interactions. Increased efflux of natural product anticancer drugs and other anticancer agents mediated by MRPs from cancer cells is associated with tumour resistance. 5.,A better understanding of the function and regulating mechanisms of MRPs could help minimize and avoid drug toxicity and unfavourable drug,drug interactions, as well as help overcome drug resistance. [source]