Development of passive permeability characteristics of rat placenta during the last third of gestation

1991 ◽  
Vol 261 (6) ◽  
pp. R1461-R1464 ◽  
Author(s):  
D. E. Atkinson ◽  
N. R. Robinson ◽  
C. P. Sibley
Keyword(s):  
Fold Increase ◽  
Passive Permeability ◽  
Permeability Characteristics ◽  
Molecular Radius

To investigate how the passive permeability of the rat placenta changes during the last third of gestation we measured the unidirectional maternofetal clearance (Kmf) of three polar nonelectrolytes. We found that Kmf (microliters.min-1.g placenta-1) for all three tracers increased between days 15 and 22 (term is 23 days). The increase was less for the largest tracer, [14C]inulin (3.5-fold increase from 0.5 +/- 0.1 to 1.6 +/- 0.1 microliters.min-1.g placenta-1), than for the smaller tracers, [14C]mannitol (7-fold increase from 1.6 +/- 0.1 to 10.9 +/- 0.4 microliters.min-1.g placenta-1) and 51Cr-labeled EDTA (9.5-fold increase from 0.8 +/- 0.04 to 7.6 +/- 0.7 microliters.min-1.g placenta-1). These data suggest that whilst the overall permeability of the rat placenta increases during this period of pregnancy, restriction to the diffusion of large (greater than or equal to 1.5 nm molecular radius) polar nonelectrolytes also increases.

Bulk flow and diffusion in the cerebrospinal fluid system of the goat

1962 ◽  
Vol 203 (5) ◽  
pp. 775-781 ◽  
Author(s):  
S. R. Heisey ◽  
D. Held ◽  
J. R. Pappenheimer
Keyword(s):  
Cerebrospinal Fluid ◽  
Porous Membranes ◽  
Perfusion Fluid ◽  
Passive Permeability ◽  
Fluid System ◽  
Permeability Characteristics ◽  
Bulk Absorption ◽  
Subarachnoid Spaces ◽  
The Difference ◽  
And Diffusion

Ventriculocisternal perfusions were carried out on chronically prepared, unanesthetized goats. Measurements were made of steady-state rates at which inulin, fructose, creatinine, urea, K, Na, and labeled water (TOH) were removed from perfusion fluid at various hydrostatic and osmotic pressures. The ventricular system is virtually impermeable to inulin. Inulin is removed from subarachnoid spaces by bulk absorption at rates which vary linearly with hydrostatic pressure. Net absorption ceases at –15 cm H2O. Rate of net formation of cerebrospinal fluid (CSF) is equal to inulin clearance plus the difference between outflow and inflow rates; normally it averages 0.16 cm3 min–1 and is essentially independent of hydrostatic pressures in the range –10 to +30 cm H2O. Net rate of formation is linearly related to total osmotic pressure differences between plasma and CSF. The coefficient of osmotic flow is greater than that measured from diffusion of TOH, as in other porous membranes. Passive permeability characteristics resemble those of the vasopressin-treated toad bladder.

NaCl transport in mouse medullary thick ascending limbs. III. Modulation of the ADH effect by peritubular osmolality

1981 ◽  
Vol 241 (4) ◽  
pp. F443-F451 ◽  
Author(s):  
S. C. Hebert ◽  
R. M. Culpepper ◽  
T. E. Andreoli
Keyword(s):  
Cell Volume ◽  
Passive Permeability ◽  
Nacl Transport ◽  
Ionic Permeability ◽  
Permeability Characteristics ◽  
Nacl Absorption ◽  
Nacl Concentration ◽  
Transepithelial Voltage

We evaluated the effects of increasing bath osmolality on both the passive permeability properties and the ADH-dependent rates of net Cl- absorption in isolated mouse medullary thick ascending limbs of Henle (mTALH). Increases in both osmolality to 900 mosmol/kg H2O with 600 mM urea had no effect on either the electrical (PNa/PCl ratio, 1.7 and 1.9 with and without peritubular urea, respectively) or tracer (PNa, 0.21 and 0.22 micrometers . s-1 with and without peritubular urea, respectively) ionic permeability characteristics of the mTALH. However, this degree of urea bath hypertonicity reduced reversibly both JnetNaCl, the net rate of transepithelial NaCl absorption, and Ve, the spontaneous transepithelial voltage: JnetNaCl fell by 85% and Ve by 70%. Both of these latter effects could be accounted for quantitatively by an 85% reduction in tau NaCl, the rate of conservative transcellular NaCl transport. The inhibition of Ve by peritubular medium urea hypertonicity was not altered by supramaximal bath concentrations of ADH, supramaximal bath concentrations of cAMP analogues, or symmetrical addition of urea to perfusate and bath. Increases in peritubular medium mannitol concentrations also reduced Ve; the inhibition of Ve was not reversed by supramaximal bath concentrations of aDH. Cell volume remained unchanged with peritubular urea but was reduced by peritubular mannitol. These data indicate that in the mTALH increases in bath osmolality with nonelectrolytes inhibit tau NaCl noncompetitively with respect to ADH or cAMP and independently of cell volume. JnetCl was also reduced with increases in peritubular medium NaCl concentration and was associated with a reduction in cell volume.

Passive Permeability in Experimental Intestinal Damage in Rats

1981 ◽  
Vol 60 (1) ◽  
pp. 115-118 ◽  
Author(s):  
I. Cobden ◽  
Jill Rothwell ◽  
A. T. R. Axon
Keyword(s):  
Villous Atrophy ◽  
Molecular Size ◽  
Mucosal Damage ◽  
Intestinal Damage ◽  
Passive Permeability ◽  
Crypt Hyperplasia ◽  
Pass Through ◽  
Mucosal Surface Area ◽  
Cell Shedding ◽  
Molecular Radius

1. Experiments were performed to study the absorption of two simultaneously administered polar probes of different molecular size from closed intestinal loops in rats subjected to various mucosal structural lesions. 2. Absorption of mannitol (molecular radius approximately 0.40 nm) was significantly decreased in rats with villous atrophy and crypt hypoplasia induced by the cytostatic agent methotrexate. The absorption of lactulose (radius approximately 0.54 nm) was also decreased, in contrast to the increased absorption which was found in an earlier study when villous atrophy with crypt hyperplasia was induced by infection by a nematode. The effect of local damage to villous tips, produced by the intraluminal presence of a detergent, was to increase significantly the absorption of lactulose. 3. In conjunction with the findings of earlier studies, these results support the hypothesis that there are at least two routes for the permeation of polar molecules. Small molecules such as mannitol probably pass through numerous cellular pores with a maximum radius lying between 0.40 and 0.54 nm and absorption is closely related to mucosal surface area. Larger molecules such as lactulose are probably restricted to less numerous extracellular pathways and absorption may be related to cell shedding or other areas of mucosal damage.

Physical Properties of Isolated Perfused Renal Tubular Basement Membranes

1971 ◽  
Vol 29 ◽  
pp. 390-391
Author(s):  
Jared Grantham ◽  
Larry Welling
Keyword(s):  
Basement Membrane ◽  
Basement Membranes ◽  
Transport Mechanisms ◽  
Permeability Characteristics ◽  
Peritubular Capillaries ◽  
Strategic Location ◽  
Tubular Lumen ◽  
Glomerular Filtrate ◽  
Urine Formation ◽  
Renal Tubular

In the course of urine formation in mammalian kidneys over 90% of the glomerular filtrate moves from the tubular lumen into the peritubular capillaries by both active and passive transport mechanisms. In all of the morphologically distinct segments of the renal tubule, e.g. proximal tubule, loop of Henle and distal nephron, the tubular absorbate passes through a basement membrane which rests against the basilar surface of the epithelial cells. The basement membrane is in a strategic location to affect the geometry of the tubules and to influence the movement of tubular absorbate into the renal interstitium. In the present studies we have determined directly some of the mechanical and permeability characteristics of tubular basement membranes.

Detection of viruses by electron microscopy: Increased sensitivity by direct micro-ultracentrifugation of samples

1987 ◽  
Vol 45 ◽  
pp. 908-909
Author(s):  
Alain R. Trudel ◽  
M. Trudel
Keyword(s):  
Electron Microscopy ◽  
Fold Increase ◽  
Observation Time ◽  
Clinical Samples ◽  
Maximum Speed ◽  
Viral Particles ◽  
Structural Details ◽  
Latex Spheres ◽  
Increased Sensitivity ◽  
Size Of Particles

AirfugeR (Beckman) direct ultracentrifugation of viral samples on electron microscopy grids offers a rapid way to concentrate viral particles or subunits and facilitate their detection and study. Using the A-100 fixed angle rotor (30°) with a K factor of 19 at maximum speed (95 000 rpm), samples up to 240 μl can be prepared for electron microscopy observation in a few minutes: observation time is decreased and structural details are highlighted. Using latex spheres to calculate the increase in sensitivity compared to the inverted drop procedure, we obtained a 10 to 40 fold increase in sensitivity depending on the size of particles. This technique also permits quantification of viral particles in samples if an aliquot is mixed with latex spheres of known concentration.Direct ultracentrifugation for electron microscopy can be performed on laboratory samples such as gradient or column fractions, infected cell supernatant, or on clinical samples such as urine, tears, cephalo-rachidian liquid, etc..

Advantages of Complementary Stereo Images as Viewed with the Low-Temperature Field-Emission SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1314-1315
Author(s):  
William P. Wergin ◽  
Eric F. Erbe
Keyword(s):  
Fold Increase ◽  
Horizontal Displacement ◽  
Three Dimensions ◽  
Stereo Image ◽  
Stereo Pair ◽  
Sem Micrograph ◽  
Left And Right ◽  
The Common ◽  
The Brain ◽  
Pair Analysis

The eye-brain complex allows those of us with normal vision to perceive and evaluate our surroundings in three-dimensions (3-D). The principle factor that makes this possible is parallax - the horizontal displacement of objects that results from the independent views that the left and right eyes detect and simultaneously transmit to the brain for superimposition. The common SEM micrograph is a 2-D representation of a 3-D specimen. Depriving the brain of the 3-D view can lead to erroneous conclusions about the relative sizes, positions and convergence of structures within a specimen. In addition, Walter has suggested that the stereo image contains information equivalent to a two-fold increase in magnification over that found in a 2-D image. Because of these factors, stereo pair analysis should be routinely employed when studying specimens.Imaging complementary faces of a fractured specimen is a second method by which the topography of a specimen can be more accurately evaluated.

Prevalence of Self-Reported Depression Symptoms and Perceived Anxiety Among Community-Dwelling U.S. Adults Reporting Tinnitus

2020 ◽  
Vol 5 (4) ◽  
pp. 959-970
Author(s):  
Kelly M. Reavis ◽  
James A. Henry ◽  
Lynn M. Marshall ◽  
Kathleen F. Carlson
Keyword(s):  
Mental Health ◽  
Fold Increase ◽  
Community Dwelling ◽  
Self Report ◽  
Depression Symptoms ◽  
Community Based Interventions ◽  
Data Set ◽  
Health Distress ◽  
Validated Questionnaire ◽  
Mental Health Distress

Purpose The aim of this study was to examine the relationship between tinnitus and self-reported mental health distress, namely, depression symptoms and perceived anxiety, in adults who participated in the National Health and Nutrition Examinations Survey between 2009 and 2012. A secondary aim was to determine if a history of serving in the military modified the associations between tinnitus and mental health distress. Method This was a cross-sectional study design of a national data set that included 5,550 U.S. community-dwelling adults ages 20 years and older, 12.7% of whom were military Veterans. Bivariable and multivariable logistic regression was used to estimate the association between tinnitus and mental health distress. All measures were based on self-report. Tinnitus and perceived anxiety were each assessed using a single question. Depression symptoms were assessed using the Patient Health Questionnaire, a validated questionnaire. Multivariable regression models were adjusted for key demographic and health factors, including self-reported hearing ability. Results Prevalence of tinnitus was 15%. Compared to adults without tinnitus, adults with tinnitus had a 1.8-fold increase in depression symptoms and a 1.5-fold increase in perceived anxiety after adjusting for potential confounders. Military Veteran status did not modify these observed associations. Conclusions Findings revealed an association between tinnitus and both depression symptoms and perceived anxiety, independent of potential confounders, among both Veterans and non-Veterans. These results suggest, on a population level, that individuals with tinnitus have a greater burden of perceived mental health distress and may benefit from interdisciplinary health care, self-help, and community-based interventions. Supplemental Material https://doi.org/10.23641/asha.12568475

1348: Sildenafil Citrat Causes a 3 Fold Increase in Periurethral Prostatic Blood Flow

2004 ◽  
Vol 171 (4S) ◽  
pp. 355-355 ◽  
Author(s):  
Germar M. Pinggera ◽  
Antonius Schuster ◽  
Ferdinand Frauscher ◽  
Georg Bartsch ◽  
Hannes Strasser
Keyword(s):  
Blood Flow ◽  
Fold Increase

Increased Expression of u-PA and u-PAR on Monocytes by LDL and Lp(a) Lipoproteins – Consequences for Plasmin Generation and Monocyte Adhesion

1999 ◽  
Vol 81 (04) ◽  
pp. 594-560 ◽  
Author(s):  
Florence Ganné ◽  
Marc Vasse ◽  
Jean-Louis Beaudeu ◽  
Jacqueline Peynet ◽  
Arnaud François ◽  
...  
Keyword(s):  
Fold Increase ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Atheromatous Plaque ◽  
Monocyte Adhesion ◽  
Blood Monocytes ◽  
Proteolytic Cascade ◽  
Ecm Degradation ◽  
Dose Dependent Increase ◽  
Dose Dependent

SummaryMonocyte-derived foam cells figure prominently in rupture-prone regions of atherosclerotic plaque. As urokinase/urokinase-receptor (u-PA/u-PAR) is the trigger of a proteolytic cascade responsible for ECM degradation, we have examined the effect of atherogenic lipoproteins on monocyte surface expression of u-PAR and u-PA. Peripheral blood monocytes, isolated from 10 healthy volunteers, were incubated with 10 to 200 µg/ml of native or oxidised (ox-) atherogenous lipoproteins for 18 h and cell surface expression of u-PA and u-PAR was analysed by flow cytometry. Both LDL and Lp(a) induced a dose-dependent increase in u-PA (1.6-fold increase with 200 μg/ml of ox-LDL) and u-PAR [1.7-fold increase with 200 μg/ml of ox-Lp(a)]. There is a great variability of the response among the donors, some of them remaining non-responders (absence of increase of u-PA or u-PAR) even at 200 μg/ml of lipoproteins. In positive responders, enhanced u-PA/u-PAR is associated with a significant increase of plasmin generation (1.9-fold increase with 200 μg/ml of ox-LDL), as determined by an amidolytic assay. Furthermore, monocyte adhesion to vitronectin and fibrinogen was significantly enhanced by the lipoproteins [respectively 2-fold and 1.7-fold increase with 200 μg/ml of ox-Lp(a)], due to the increase of u-PAR and ICAM-1, which are receptors for vitronectin and fibrinogen. These data suggest that atherogenous lipoproteins could contribute to the development of atheromatous plaque by increasing monocyte adhesion and trigger plaque weakening by inducing ECM degradation.

The Effect of Haematoporphyrin Derivative on the Uptake of 67Ga, 59Fe and 65Zn in Tumours

1978 ◽  
Vol 17 (06) ◽  
pp. 262-265
Author(s):  
A. Phillips Carol ◽  
D.M. Taylor
Keyword(s):  
Fold Increase ◽  
Haematoporphyrin Derivative ◽  
Tumour Bearing ◽  
Rats And Mice ◽  
Prior Administration

The effect of prior administration of haematoporphyrin derivative on the uptake in tumours of 67Ga, 59Fe and 65Zn has been studied in tumour-bearing rats and mice. An approximately two-fold increase in the uptake of 67Ga was observed in the August 15 rat tumour when the nuclide was administered 17 to 24 hr after haematoporphyrin. No increase in the uptake of 67Ga occurred in three mouse tumours. Haematoporphyrin administration did not affect the uptake of 65Zn and 59Fe in any of the tumour systems. It is concluded that the presence of haematoporphyrin does not markedly increase the ability of tumours to accummulate metallic radionuclides.

Sign in / Sign up

Export Citation Format

Share Document