The pressure effects of different commercially available beverages on food boluses in vitro

2020 ◽  
Author(s):  
Yousef Ibrahim ◽  
Simon Browning
Keyword(s):  
Pressure Effects

scholarly journals THE VARIATIONS OF WATER IN HUMAN TISSUE UNDER CERTAIN COMPRESSION: STUDIED WITH DIFFUSE REFLECTANCE SPECTROSCOPY

2013 ◽  
Vol 06 (01) ◽  
pp. 1350005 ◽  
Author(s):  
CHENXI LI ◽  
JINGYING JIANG ◽  
KEXIN XU
Keyword(s):  
Human Tissue ◽  
Fiber Optic ◽  
Reflectance Spectrum ◽  
Diffuse Reflectance Spectroscopy ◽  
Pressure Effects ◽  
Water Volume ◽  
Fiber Optic Probe ◽  
Optic Probe

The reflectance spectrum has been widely adopted to extract diagnosis information of human tissue because it possesses the advantages of noninvasive and rapidity. The external pressure brought by fiber optic probe may influence the accuracy of measurement. In this paper, a systematic study is focused on the effects of probe pressure on intrinsic changes of water and scattering particles in tissue. According to the biphasic nonlinear mixture model, the pressure modulated reflectance spectrum of both in vitro and in vivo tissue is measured and processed with second-derivation. The results indicate that the variations of bulk and bonded water in tissue have a nonlinear relationship with the pressure. Differences in tissue structure and morphology contribute to site-specific probe pressure effects. Then the finite element (FEM) and Monte Carlo (MC) method is employed to simulate the deformation and reflectance spectrum variations of tissue before and after compression. The simulation results show that as the pressure of fiber optic probe applied to the detected skin increased to 80 kPa, the effective photon proportion form dermis decreases significantly from 86% to 76%. Future designs might benefit from the research of change of water volume inside the tissue to mitigate the pressure applied to skin.

A model of osmotic and hydrostatic pressure effects on volume absorption in the proximal tubule

1987 ◽  
Vol 253 (3) ◽  
pp. F563-F575
Author(s):  
J. C. Williams ◽  
J. A. Schafer
Keyword(s):  
Hydrostatic Pressure ◽  
Proximal Tubule ◽  
Water Permeability ◽  
Solute Concentration ◽  
Pressure Effects ◽  
Good Prediction ◽  
Osmotic Water Permeability ◽  
Volume Absorption ◽  
Osmotic Water

A computer model of the proximal tubule of the rabbit is described in which the tubule is treated as a single cylindrical barrier to the flow of solute and water between lumen and bath, and volume absorption is assumed to be driven exclusively by hydrostatic and osmotic pressure differences across this barrier. The model mimics the function of the tubule in two in vitro preparations: in simulations of the isolated tubule perfused under oil, the model correctly describes the solute concentration gradients that exist between the perfusate and absorbate and predicts differences in solute concentrations among absorbate droplets on the same tubule if luminal concentration becomes limiting. This prediction was tested experimentally with glucose and found to be correct. In simulations of the tubule perfused in an aqueous bath, the role of transmural hydrostatic pressure was explored; it is predicted that, at normal rates of in vitro perfusion (approximately 10 nl/min), increases in pressure have very little effect on volume absorption but can greatly alter the osmotic differences present across the wall of the tubule, especially with high values of osmotic water permeability. At high rates of perfusion, the ability of the tubule to produce a lumen hypotonic to the bath is reduced, but the direct effects of pressure on volume absorption become more apparent, resulting in relatively little effect of perfusion rate on volume absorption if the osmotic water permeability is sufficiently high. A similar relationship was seen experimentally. In all, this simple model provides a good prediction of function in isolated perfused tubules without any assumptions of hypertonic compartments within the epithelium.

scholarly journals Urea treatment of rice straw at elevated temperature and pressure: Effects on fiber content, rumen fermentation and digestibility

2017 ◽  
Vol 42 (2) ◽  
pp. 81 ◽  
Author(s):  
A. Jayanegara ◽  
R. S. K. Ayinda ◽  
E. B. Laconi
Keyword(s):  
Elevated Temperature ◽  
Rice Straw ◽  
Pressure Effects ◽  
Test Results ◽  
Short Treatment ◽  
Urea Treatment ◽  
Temperature And Pressure ◽  
Post Hoc ◽  
In Vitro Data

The objective of this study was to apply urea treatment of rice straw at elevated temperature and pressure (121oC; 1.4 atm) and at short treatment period (30 or 60 min) in comparison to conventional urea treatment (4 weeks incubation). Rice straw was subjected to the following treatments: RS1: untreated rice straw (control), RS2: RS1+1% urea (no incubation), RS3:RS1+1% urea (4 weeks incubation), RS4: RS2+autoclave 30 min, RS5: RS3+autoclave 30 min, RS6: RS2+autoclave 60 min, RS7: RS3+autoclave 60 min. The samples were analyzed for fiber contents and incubated in vitro. Data were analyzed using analysis of variance and Duncan’s post-hoc test. Results showed that urea treatments (RS3-RS7) did not change NDF and ADF contents of rice straw in comparison to control. Urea treatment in autoclave for 30 min (RS4) increased rice straw IVDMD and IVOMD by 23.3% and 25.6% as compared to control, respectively (P<0.05). Extension of the incubation period to 60 min (RS6) did not improve further the IVDMD and IVOMD. Treatments did not change pH values and NH3 concentrations. Urea treatment (RS3-RS7) increased total VFA concentration in comparison to control (P<0.05). It was concluded that urea treatment using autoclave for 30 min may replace conventional urea treatment to improve nutritional value of rice straw.

Mg2+-induced endothelium-dependent relaxation of blood vessels and blood pressure lowering: role of NO

2000 ◽  
Vol 278 (3) ◽  
pp. R628-R639 ◽  
Author(s):  
Zhi-Wei Yang ◽  
Asefa Gebrewold ◽  
Maja Nowakowski ◽  
Bella T. Altura ◽  
Burton M. Altura
Keyword(s):  
Blood Pressure ◽  
Blood Vessels ◽  
Pressure Effects ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Arterial Blood ◽  
No Release ◽  
Endothelium Dependent Relaxation

In vitro extracellular Mg2+ concentration ([Mg2+]0) produces endothelium-dependent and endothelium-independent relaxations in rat aorta in a concentration-dependent manner. These relaxant effects of Mg2+ on intact rat aortic rings, but not denuded rat aortic rings, were suppressed by either N G-monomethyl-l-arginine (l-NMMA), N ω-nitro-l-arginine methyl ester (l-NAME), or methylene blue. The inhibitory effects of l-NMMA and l-NAME could be reversed partly by l-arginine. [Mg2+]0-induced dilatation in vivo in rat mesenteric arterioles and venules was almost completely inhibited by N G-nitro-l-arginine andl-NMMA. Removal of extracellular Ca2+concentration ([Ca2+]0) or buffering intracellular Ca2+ concentration in endothelial cells, with 10 μM 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid-AM, markedly attenuated the relaxant effects of Mg2+. Mg2+ produced nitric oxide (NO) release from the intact aortic rings in a concentration-dependent manner. Removal of [Ca2+]0 diminished the increased NO release induced by elevated levels of [Mg2+]0. In vivo infusion of increasing doses (1–30 μM/min) of MgSO4, directly into the femoral veins of anesthetized rats, elicited significant concentration-dependent sustained increases in serum total Mg and concomitant decreases in arterial blood pressure. Before and after employment of various doses of MgSO4, intravenous administration of either l-NMMA (10 mg/kg) orl-NAME (10 mg/kg) increased (i.e., reversed) the MgSO4-lowered blood pressure markedly, and intravenous injection of l-arginine restored partially the increased blood pressure effects of both l-NMMA andl-NAME. Our results suggest that 1) small blood vessels are very dependent on NO release for Mg2+dilatations and 2) the endothelium-dependent relaxation induced by extracellular Mg2+ is mediated by release of endothelium-derived relaxing factor-NO from the endothelium, and requires Ca2+ and formation of guanosine 3′,5′-cyclic monophosphate.

Arterial pressure effects on preglomerular microvasculature of juxtamedullary nephrons

1990 ◽  
Vol 258 (1) ◽  
pp. F94-F102 ◽  
Author(s):  
P. K. Carmines ◽  
E. W. Inscho ◽  
R. C. Gensure
Keyword(s):  
Arterial Pressure ◽  
Capillary Pressure ◽  
Branch Point ◽  
Perfusion Pressure ◽  
Pressure Effects ◽  
Arterial Perfusion ◽  
Glomerular Capillary ◽  
Glomerular Capillary Pressure ◽  
Afferent Arterioles

Videomicroscopic and micropuncture techniques were utilized to determine segmental microvascular responses of in vitro blood-perfused juxtamedullary nephrons to step changes in renal arterial perfusion pressure (PP). At a PP of 104 +/- 2 mmHg, inside diameters of arcuate arteries (ARC), interlobular arteries (ILA), and afferent arterioles (AFF) averaged 68.6 +/- 6.4, 35.7 +/- 1.5, and 20.4 +/- 2.3 microns, respectively. Variations in PP within the range of 70-180 mmHg elicited alterations in microvessel diameters with the following slopes: ARC, -0.15 micron/mmHg; ILA, -0.13 micron/mmHg; and AFF, -0.14 micron/mmHg. In other experiments, intravascular pressures were measured during changes in PP. Glomerular capillary pressure was well regulated (slope = 0.19 +/- 0.03 mmHg/mmHg), and mid-AFF pressure was partially regulated (slope = 0.60 +/- 0.17 mmHg/mmHg); however, pressure measured at the ILA-AFF branch point responded passively to changes in PP (slope = 0.95 +/- 0.06 mmHg/mmHg). These observations reveal that, although the entire preglomerular vasculature of juxtamedullary nephrons is capable of actively responding to changes in PP, afferent arterioles are responsible for the predominant resistance adjustment throughout the normal autoregulatory range.

Synthesis, in Vitro Evaluation, and Intraocular Pressure Effects of Water-Soluble Prodrugs of Endocannabinoid Noladin Ether

2003 ◽  
Vol 46 (23) ◽  
pp. 5083-5086 ◽  
Author(s):  
Juha Juntunen ◽  
Jouko Vepsäläinen ◽  
Riku Niemi ◽  
Krista Laine ◽  
Tomi Järvinen
Keyword(s):  
Intraocular Pressure ◽  
Water Soluble ◽  
Pressure Effects ◽  
In Vitro Evaluation

Comparative effects of leukotrienes on porcine pulmonary circulation in vitro and in vivo

1987 ◽  
Vol 63 (2) ◽  
pp. 582-588 ◽  
Author(s):  
H. Ohtaka ◽  
J. Y. Tsang ◽  
A. Foster ◽  
J. C. Hogg ◽  
R. R. Schellenberg
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Vein ◽  
Diastolic Pressure ◽  
Direct Action ◽  
Left Ventricular ◽  
Pressure Effects ◽  
Pulmonary Vasculature ◽  
Pulmonary Arterial

The present study examined the effect of leukotrienes on porcine pulmonary vasculature both in vivo and in vitro. In vitro studies using isolated vascular strips demonstrated that pulmonary arterial smooth muscle contracted to leukotriene C4 (LTC4), whereas pulmonary vein smooth muscle did not. Pulmonary arterial contraction was due to both the direct action of LTC4 and secondarily generated thromboxane A2 (TxA2). In vivo, LTC4 injection caused a pronounced but transient increase in pulmonary arterial pressure and pulmonary arterial wedge pressure (Ppw), with a smaller effect on left ventricular end-diastolic pressure. Effects of LTD4 were smaller with comparable pressure changes at all three sites, suggesting a primary cardiac effect. Like LTC4, histamine caused a disproportionate increase in Ppw vs. left ventricular end-diastolic pressure. These observations suggest that LTC4 causes pulmonary venoconstriction in vivo despite its lack of effect on pulmonary vein smooth muscle in vitro. This discrepancy may be due to venoconstrictor effects of TxA2 generated from upstream pulmonary arterial vessels.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

In Vitro Induction of Crystals of MT Protein by Vinblastine-Colcemid in Mouse Spermatids

1974 ◽  
Vol 32 ◽  
pp. 132-133
Author(s):  
John J. Wolosewick ◽  
John H. D. Bryan
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Nuclear Ring ◽  
Rough Er ◽  
Distal Direction ◽  
In Vitro Induction

Early in spermiogenesis the manchette is rapidly assembled in a distal direction from the nuclear-ring-densities. The association of vesicles of smooth endoplasmic reticulum (SER) and the manchette microtubules (MTS) has been reported. In the mouse, osmophilic densities at the distal ends of the manchette are the organizing centers (MTOCS), and are associated with the SER. Rapid MT assembly and the lack of rough ER suggests that there is an existing pool of MT protein. Colcemid potentiates the reaction of vinblastine with tubulin and was used in this investigation to detect this protein.

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