Lanthanum-induced damage to microvilli in cells of the posterior epithelium of the cornea and its trigger mechanism

Destructions in filament-membranous connections of microvilli of cells of the rabbit corneal posterior epithelium have been investigated after the effect of an ionized form of lanthanum. Rare-earth ions are used as a specific antagonist and as a substituent for calcium on the surface of biopolymeres. Twelve corneas from 6 rabbits of Shinshilla strain at the age of 2 months are used. Lanthanum ions are stated to have selective connections with the luminal part of the plasmolemma and with the membrane of the microvilli in the cells of the corneal posterior epithelium. The changes in the microvilli are accompanied with destruction of the filament-membranous connections producing protrusions and vesiculation of their plasmolemma, disaggregation of microfilaments adjoining the luminal part of the cellular plasmolemma. A suggestion is made on an impostant role of calcium and C++-binding biopolymeres in the mechanism regulating the filament-membranous connections.     

Damage and regeneration of the endothelium of the aorta in experimental hypercholesterolemia

In dynamics of the experimental hypercholesterolemia in rabbits, peculiarities of endothelial regeneration have been studied. Comparison of proliferative activity level in endotheliocytes with structural-functional state of the endothelial monolayer at atherogenesis makes it possible to consider, that the lesion of the endothelium cannot be regarded as an initiating factor for formation of atherosclerotic lesions. Formation of the lesions in the internal lining of the arteries is preceded by certain disorders in permeability of the endothelial barrier at increasing concentration of cholesterin in blood plasma, accompanying with a sharp activation of the cell proliferative activity. When lipid plates and atherosclerotic plaques are already formed, the processes of the endothelial damage and regeneration occur in parallel. The regeneration is ensured with an intensive proliferation and growth of endotheliocytes onto deendotheliolized areas of the damaged intima.     

The relief of the luminal surface of the sinuses in the mammalian cranial dura mater]

In Mammalia with different types in organization of blood outflow in the dura mater venous sinuses: vertebral (tiger), jugular (fur-seal, cat, rabbit) and mixed (rat, dog, man) the internal surface relief of these sinuses has been studied. The total plan of the relief in all the species studied is principally the same. It is characterized with presence of visually determined macro-relief structures: Pacchionian bodies, trabeculae, bars, eminences and excavations in places, where the sinuses fuse, initial folds (micro-relief) and, at last, formations composed by the nucleus and the external membrane of endotheliocytes (ultra-relief). The micro-relief depends on the type of the venous outflow from the brain. In the animals with the jugular type of the outflow the longitudinal folds are more expressed; in the animals with the vertebral type--there occur folds with transversal orientation. For the representatives with the mixed type--multilayered elastic carcass is specific. At the same time, the development degree of the micro-relief with a similar type of blood outflow is different. The relief of the luminal surface of the longitudinal venous sinus of the mammalian dura mater is supposed to be determined by presence of extravascular formations, by the muscular structures tonus, by construction of the wall elastic carcass and by activity of the luminal part of the external membrane of endotheliocytes.     

Effect of protamine on the composition of blood lipoproteins at various periods of hypercholesterolemia in rabbits

Protamine has been studied for its effect on changes in the protein-lipid composition of main fractions of blood lipoproteins in different periods (1- and 7-months) of hypercholesterolemia in rabbits. Daily introduction of protamine to intact animals for 30 days did not change the studied parameters. Results of analysis of the protamine action against the background of the 1-month hypercholesterolemia testify to an increase of the protein and cholesterin concentration in apoB-containing lipoproteins. A moderate increase of the cholesterin concentration in the HDL composition has been observed, the protein concentration remaining at high level. The atherogenic diet for 7 month has induced in animals subjected to its dyslipoproteinemia and atherosclerosis of vessels. Under these conditions protamine has inhibited "proatherogenic" alterations in the composition of lipoproteins. The concentration of protein, cholesterin and triglycerides in the apoB-containing fractions decreased and the concentration of total cholesterin and triglycerides in the blood serum fell considerably.     

Ultrastructure of the inner surface of the aorta of mature and old animals

In the experiments, performed on 12 white rats and 8 rabbits, by means of scanning electron microscopy of the native preparations and in a number of cases with use of silver nitrate impregnation, the internal surface structure has been studied in the aortal membrane of mature and old animals. At ageing the integrity and continuity of the endothelial monolayer is preserved, on the surface local intimal pits, craters and microdefects appear, adhesiveness of endothelium to leucocytes increases. Orientation of the intimal folds is disturbed. The type of the senescent remodeling in the endothelial layer revealed predisposes to development of atherosclerosis.     

Structuro-functional features of different links in the microhemocirculatory bed of the myocardium

Morphofunctional peculiarities of various elements of the microhemocirculatory bed (MHCB) of the myocardium performing correction of the nutritive blood stream, structures and mechanisms of the microvessel permeability have been studied. The investigation has been performed on 20 mature rabbits and 5 mongrel dogs, transmissive electron microscopy and certain cytochemical techniques applied for revealing ATP-ase, lactate-, malate-, succinate-dehydrogenases, cytochrome-C-reductase and glycosamine glycans. Structural differences in microvessels of various range are described. Together with smooth muscle cells in arterioles and precapillary sphincters, specialized endotheliocytes and valve-like formations, situating in the orifices of blood capillaries, participate in regulation of hemoperfusion of the MHCB functional units. The data have been obtained characterising cytolemma of the endotheliocytes as a complex system, where plasmolemma, being the bearer of ATP-ase and a complex of oxidoreductase, regulates physical-chemical properties of the paraplasmolemmal layer and ensures the control of all the forms of the transcapillary transport. Micropinocytic vesicles are proved to differentiate into two functionally asynonymous populations: one of them performs the energy-dependent transport, while the other reserves the plasmolemma.     

State of the endothelium of the aorta during chronic stress

In 50 white male rats (18-control and 32-experimental) using morphometrical and stereological methods for film preparations of endothelium, the state of the internal aortal lining at various stages of chronic stress developing during muscular activity has been studied. The data obtained are statistically treated by the sliding averages method, reliability of the differences is estimated according to the value of nonparametrical criterion of Wilcoxon-Mann-Whitney. For objective periodization of the endothelial reaction to stress, centered moving averages curves are performed with subsequent calculation of the coefficient of variation for the aligned ordinates of the approximated values in every temporal point. The aortal endothelium reaction to the stress is of phasic character. During the alarm reaction, destructive changes predominate; they are accompanied with an increased mitotic activity of endotheliocytes up to 2.2%. The resistance stage increases compensatory-adaptive rearrangements, which are manifested not only as cellular hyperplasia, but as hyperthrophy of nuclei, increasing number of strangulated nuclei, nucleoli, as well as binuclear and trinucler cells. To the exhaustion period the increase of alternative and restorative transformations of the tissue corresponds.     

Low-density lipoprotein concentration in the normal left coronary artery tree

Background

The blood flow and transportation of molecules in the cardiovascular system plays a crucial role in the genesis and progression of atherosclerosis. This computational study elucidates the Low Density Lipoprotein (LDL) site concentration in the entire normal human 3D tree of the LCA.

Methods

A 3D geometry model of the normal human LCA tree is constructed. Angiographic data used for geometry construction correspond to end-diastole. The resulted model includes the LMCA, LAD, LCxA and their main branches. The numerical simulation couples the flow equations with the transport equation applying realistic boundary conditions at the wall.

Results

High concentration of LDL values appears at bifurcation opposite to the flow dividers in the proximal regions of the Left Coronary Artery (LCA) tree, where atherosclerosis frequently occurs. The area-averaged normalized luminal surface LDL concentrations over the entire LCA tree are, 1.0348, 1.054 and 1.23, for the low, median and high water infiltration velocities, respectively. For the high, median and low molecular diffusivities, the peak values of the normalized LDL luminal surface concentration at the LMCA bifurcation reach 1.065, 1.080 and 1.205, respectively. LCA tree walls are exposed to a cholesterolemic environment although the applied mass and flow conditions refer to normal human geometry and normal mass-flow conditions.

Conclusion

The relationship between WSS and luminal surface concentration of LDL indicates that LDL is elevated at locations where WSS is low. Concave sides of the LCA tree exhibit higher concentration of LDL than the convex sides. Decreased molecular diffusivity increases the LDL concentration. Increased water infiltration velocity increases the LDL concentration. The regional area of high luminal surface concentration is increased with increasing water infiltration velocity. Regions of high LDL luminal surface concentration do not necessarily co-locate to the sites of lowest WSS. The degree of elevation in luminal surface LDL concentration is mostly affected from the water infiltration velocity at the vessel wall. The paths of the velocities in proximity to the endothelium might be the most important factor for the elevated LDL concentration.     

Electromechanical properties of the single cell-layered heart of tunicate Boltenia ovifera (sea potato)

The tubular heart of the sea potato is composed of a single layer of myoepithelial cells interconnected near the extraluminal surface by specialized junctions. If these junctions are used as the border which separates the luminal from extraluminal membrane, the surface area ratio, luminal:extraluminal, is approximately 12:1. A single myofibril is located near the luminal surface in each cell. Current passed across the heart wall in the direction that depolarizes the luminal membrane and hyperpolarizes the extraluminal membrane immediately produces "all- or-none" action potentials and contractions. Current passed in the opposite direction fails to produce action potentials until after the break of the stimulus, suggesting anodal break excitation of the hyperpolarized luminal membrane. High potassium solutions depolarized the myoepithelium and produced contractions only when applied to the luminal surface of the heart. [Ca]0 increases and [Mg]0 decreases twitch tension only on the luminal surface of the heart. The transwall resistivity is low (50-100 omega/cm2) due to an extracellular shunt. Because of this shunt and the larger surface area of the luminal membrane, the extraluminal membrane is effectively clamped to the potential of the luminal membrane and is not capable of directly influencing excitation-contraction coupling. These findings suggest that only the luminal membrane of the sea potato myoepithelium is capable of generating an action potential and triggering contraction.     

Ultrastructural localization of adenylate cyclase and guanylate cyclase activity in the gastric gland cells of rats with hormonal imbalance

Electron histochemical investigation of the rat gastric mucous membrane has demonstrated that an abundant amount of thyroxine administered increases adenylate cyclase (AC) activity in the basal part of plasmolemma of parietal glandulocytes. As a result of the increased AC activity, the level of cyclic adenosine monophosphate cyclic guanylate monophosphate (c GMPh) level decrease. Ultrastructural and biochemical analyses have demonstrated that when hydrocortison is administered on the background of hyperthyroidism, localization of AC and GC activity in glandulocytes, as well as c AMPh and c GMPh contents change towards opposite direction comparing to the case when thyroxine alone is administered.     

Differentiation of endocrinocytes in the small-intestinal epithelium of albino rats in ontogenesis]

By means of the light microscopy method differentiation and dynamics on contents of endocrinocytes have been studied in epithelium of the initial part of the jejunum, of the caudal part of the ileum and of the middle part between them during pre- and postnatal periods of development. Formation of the endocrine apparatus of the mucous membrane epithelium in the small intestine takes place simultaneously with tissue differentiation of the epithelial layer. The population density of endotheliocytes of the mucous membrane is maximal in the initial part of the jejunum and decreases gradually in the caudal direction. By the 15th day of the postnatal development endocrinocytes in composition of the epithelium in the small intestine reach a high level of the specific differentiation and their amount increases by 1.3 times in comparison with that in newborn animals.     

Quantitative analysis of exocytosis and endocytosis in the hydroosmotic response of toad bladder

Summary This study concerns the timing and magnitude of exocytosis and endocytosis in the granular cells of toad bladder during the hydroosmotic response to antidiuretic hormone. Granule exocytosis at the luminal cell surface is extensive within 5 min of the administration of a physiological dose of hormone. Hydroosmosis becomes detectable during this time period. The amount of membrane added to the luminal surface by exocytosis during 60 min of exposure to hormone can be of the same order of magnitude as the extent of the luminal plasma membrane. Endocytosis, demonstrated by peroxidase uptake from the luminal surface, becomes extensive during the period 15–45 min after hormone administration. Thus, maximal endocytic activity occurs later than the period of most extensive exocytosis and seems to correlate with the onset of the decline in water movement. The amount of membrane retrieved from the luminal surface by endocytosis during 60 min of stimulation is at least three quarters of that added by exocytosis. The bulk membrane movement in ADH stimulated preparations does not require the presence of an osmotic gradient. Colchicine inhibits the hydroosmotic response, the exocytosis of granules, and endocytosis at the luminal surface. These results strengthen our view that the bulk circulation of membrane at the cell surface, via exocytosis and endocytosis, is closely related to the permeability changes occuring at the surface.     

AFM study on the electric-field effects on supported bilayer lipid membranes

Electric-field induced changes in structure and conductivity of supported bilayer lipid membranes (SLM) have been studied at submicroscopic resolution using atomic force microscopy and electrochemical impedance spectroscopy. The SLMs are formed on gold surfaces modified with mixed self-assembled monolayers of a cholesterol-tether and 6-mercaptohexanol. At applied potentials of ≤−0.25 V versus standard hydrogen electrode, the conductance of the SLM increases and membrane areas of <150 nm in size are found to elevate from the surface up to 15 nm in height. To estimate the electric field experienced by the lipid membrane, electrowetting has been used to determine the point of zero charge of a 6-mercaptohexanol-modified surface (0.19 ± 0.13 V versus standard hydrogen electrode). The effects of electric fields on the structure and conductance of supported membranes are discussed.     

Specific IgE response to different grass pollen allergen components in children undergoing sublingual immunotherapy

ABSTRACT: BACKGROUND: Grass pollen is a major cause of respiratory allergy worldwide and contain a number of allergens, some of them (Phl p 1, Phl p 2, Phl p 5, and Phl 6 from Phleum pratense, and their homologous in other grasses) are known as major allergens. The administration of grass pollen extracts by immunotherapy generally induces an initial rise in specific immunoglobulin E (sIgE) production followed by a progressive decline during the treatment. Some studies reported that immunotherapy is able to induce a de novo sensitisation to allergen component previously unrecognized. METHODS: We investigated in 30 children (19 males and 11 females, mean age 11.3 years), 19 treated with sublingual immunotherapy (SLIT) by a 5-grass extract and 11 untreated, the sIgE and sIgG4 response to the different allergen components. RESULTS: Significant increases ( p < 0.001) were detected for Phl p 1, Phl p 2, Phl p 5, and Phl p 6, while sIgE levels induced in response to Phl p 7 and Phl p 12 were low or absent at baseline and unchanged following SLIT treatment; no new sensitisation was detected. As to IgG4, significant increases were found for Phl p2 and Phl p 5, while the increase for Phl p 12 was not significant. In the control group, no significant increase in sIgE for any single allergen component was found. CONCLUSIONS: These findings confirm that the initial phase of SLIT with a grass pollen extract enhances the sIgE synthesis and show that the sIgE response concerns the same allergen components which induce IgE reactivity during natural exposure.     

Membrane cholesterol modulates the fluid shear stress response of polymorphonuclear leukocytes via its effects on membrane fluidity

Continuous exposure of polymorphonuclear leukocytes (PMNLs) to circulatory hemodynamics points to fluid flow as a biophysical regulator of their activity. Specifically, fluid flow-derived shear stresses deactivate leukocytes via actions on the conformational activities of proteins on the cell surface. Because membrane properties affect activities of membrane-bound proteins, we hypothesized that changes in the physical properties of cell membranes influence PMNL sensitivity to fluid shear stress. For this purpose, we modified PMNL membranes and showed that the cellular mechanosensitivity to shear was impaired whether we increased, reduced, or disrupted the organization of cholesterol within the lipid bilayer. Notably, PMNLs with enriched membrane cholesterol exhibited attenuated pseudopod retraction responses to shear that were recovered by select concentrations of benzyl alcohol (a membrane fluidizer). In fact, PMNL responses to shear positively correlated (R(2) = 0.96; P < 0.0001) with cholesterol-related membrane fluidity. Moreover, in low-density lipoprotein receptor-deficient (LDLr(-/-)) mice fed a high-fat diet (a hypercholesterolemia model), PMNL shear-responses correlated (R(2) = 0.5; P < 0.01) with blood concentrations of unesterified (i.e., free) cholesterol. In this regard, the shear-responses of PMNLs gradually diminished and eventually reversed as free cholesterol levels in blood increased during 8 wk of the high-fat diet. Collectively, our results provided evidence that cholesterol is an important component of the PMNL mechanotransducing capacity and elevated membrane cholesterol impairs PMNL shear-responses at least partially through its impact on membrane fluidity. This cholesterol-linked perturbation may contribute to dysregulated PMNL activity (e.g., chronic inflammation) related to hypercholesterolemia and causal for cardiovascular pathologies (e.g., atherosclerosis).     

Changes of Ca2+ -ATPase Activities in Cell of Rice Seed lings During the Enhancement of Chilling Resistance Induced by Cold and Salt Pretreatment

The changes of Ca2+ -ATPase activities of plasmolemma, and tonoplast membrane in roots and leaf chloroplasts in rice ( Oryza sativa L. ) seedlings were investigated for exploring the mechanism of cross adaptation to different stresses in the plants during the enhancement of chilling resistance induced by cold and salt pretreatment. The results indicated that the chilling resistance of rice seedlings was enhanced markedly by cold and salt pretreatment, but this enhancement was inhibited by Ca2+-chelate ethyleneglycol-bis-(β-aminoethyl ether) N, N-tetraacetic acid (EGTA) and the calmodulin inhibitor chlorpromazine (CPZ), it showed the calcium messenger system was involved in the course of chilling resistance formation. The Ca2+ -ATPase activity of root plasmolemma and tonoplast membrane as well as the Fe(CN)63- reduction in root plasmolemma in nonpretreated seedlings were declined markedly during the chilling stress. The Ca2+ -ATPase activities of plasmolemma, tonoplast membrane and chloroplasts as well as the Fe(CN)63- reduction of plasmolemma were enhanced by cold pretreatment. The activities of Ca2+ -ATPase and Fe(CN)63- reduction of plasmolemma, as compared with nonpretreated seedlings has increased by 86.80% and 93.93% respectively. The effect of salt pretreatmerit on the Ca2+ -ATPase activities of plasmolemma and chloroplast as well as Fe(CN)63- reduction of plasmolemma were similar to the effect of cold pretreatment. Although the Ca2+ -ATPase activity of tonoplast membrane was declined by salt pretreatment, the activity was none the less markedly higher than that of the nonpretreated seedlings. It showed that there was stronger ability of maintaining calcium homeostasis in the seedlings following two pretreatment. The results displayed that the enhancement of chilling resistance in rice seedlings with cold and salt pretreatment might be related to the effective activation of Ca2+ -ATPase in two pretreatment seedlings, because the activated Ca2+ -ATPase could bring back rapidly the raised cytoplasmic Ca2+ concentration from chilling stress to the state of calcium homeostasis, leading to the maintenance of normal functioning of the calcium messenger system and physiological metabolism. It seems that the adapated mechanism to chilling stress in two seedlings with cold and salt pretreatment was similar.     

Concentration polarization of atherogenic lipids in the arterial system

The transport of atherogenic lipids (LDL) in a straight segment of an artery with a semi-permeable wall was simulated numerically. The numerical analysis predicted that a mass transport phenomenon called ’concentration polarization’ of LDL might occur in the arterial system. Under normal physiological flow conditions, the luminal surface LDL concentration was 5%–14% greater than the bulk concentration in a straight segment of an artery. The luminal surface LDL concentration at the arterial wall was flow-dependent, varying linearly with the filtration rate across the arterial wall and inversely with wall shear rate. At low wall shear rate, the luminal surface LDL concentration was very sensitive to changes in flow conditions, decreasing sharply as wall shear rate increased. In order to verify the numerical analysis, the luminal surface concentration of bovine serum albumin (as a tracer macromolecule) in the canine carotid artery was measured in vitro by directly taking liquid samples from the luminal surface of the artery. The experimental result was in very good agreement with the numerical analysis. The authors believe that the mass transport phenomenon of ‘concentration polarization’ may indeed exist in the human circulation and play an important role in the localization of atherosclerosis.     

Gender disparities in the association between epicardial adipose tissue volume and coronary atherosclerosis: A 3-dimensional cardiac computed tomography imaging study in Japanese subjects

ABSTRACT: BACKGROUND: Growing evidence suggests that epicardial adipose tissue (EAT) may contribute to the development of coronary artery disease (CAD). In this study, we explored gender disparities in EAT volume (EATV) and its impact on coronary atherosclerosis. METHODS: The study population consisted of 90 consecutive subjects (age: 63 +/- 12 years; men: 47, women: 43) who underwent 256-slice multi-detector computed tomography (MDCT) coronary angiography. EATV was measured as the sum of cross-sectional epicardial fat area on CT images, from the lower surface of the left pulmonary artery origin to the apex. Subjects were segregated into the CAD group (coronary luminal narrowing > 50%) and non-CAD group. RESULTS: EATV/body surface area (BSA) was higher among men in the CAD group than in the non-CAD group (62 +/- 13 vs. 33 +/- 10 cm3/m2, p < 0.0001), but did not differ significantly among women in the 2 groups (49 +/- 18 vs. 42 +/- 9 cm3/m2, not significant). Multivariate logistic analysis showed that EATV/BSA was the single predictor for >50% coronary luminal narrowing in men (p < 0.0001). Predictors excluded were age, body mass index, hypertension, diabetes mellitus, and hyperlipidemia. CONCLUSIONS: Increased EATV is strongly associated with coronary atherosclerosis in men.     

Ultracytochemical study of ATP-ase activity in mucosal parietal cells and in the cells of human adenocarcinoma of the stomach]

Ultracytochemical investigation of ATP-ase activity was carried out in parietal cells of the mucosa and in cancer cells of human stomach carcinoma possessing a similar ultrastructure. In parietal cells the reaction product of ATP-ase was observed on the membranes of microvilli of intracellular canaliculi, on the membranes delineating the lateral intercellular space, on the basal plasmolemma and in the nucleoli. The reaction product was absent on the membranes of tubuvesicles and on the apical surface of the plasmalemma. In cancer cells the reaction product was found on the membranes of the microvilli of the intracellular canaliculi, basal plasmolemma and in the nucleoli. Comparative examination of ATP-ase activity in these cells implies that at least the part of the mechanism of hydrochloric acid secretion which is involved in the transfer of H+ and Cl- is retained in cancer cells. A steady decrease in hydrochlorid acid secretion observed in the stomach mucosa in cancer as well as in the tumour itself seems to be associated with other mechanisms.     

Regulation of ADH-stimulated water flow at a post-luminal barrier in toad bladder

Recent studies show that ADH-stimulated water flow across toad bladder may be regulated at a site other than the luminal membrane. In these studies luminal membrane particle aggregate frequency has been used as a measure of luminal membrane water permeability. In fully stretched bladders the relationship between total tissue permeability and aggregate frequency is curvilinear, rather than linear. This implies a resistance in series with the luminal membrane that can become rate-limiting for water flow during ADH stimulation. The possibility that transtissue water movement is actually regulated at such a post-luminal membrane resistance is suggested by the finding that within 30 min following exposure to hormone, water flow becomes attenuated without any change in aggregate frequency. Supporting this possibility, recent data from follow-up studies suggest that the apparent water permeability per luminal membrane aggregate is not reduced with time. Finally, for bladders in which prostaglandin synthesis is inhibited (by naproxen), increases in both base-line water flow and water flow consequent to treatment with a submaximal dose of ADH (0.125 mU/ml), are much less than expected from simultaneously observed changes in luminal membrane aggregate frequency. In parallel experiments to these, moreover, direct measurements of luminal membrane water permeability from the rate of change of cell volume consequent to a transluminal membrane osmotic challenge, confirm that luminal membrane water permeability increases to the extent expected from changes in aggregate frequency. All of the data taken together argue for a post-luminal membrane barrier in toad bladder which regulates tissue permeability during ADH stimulation.