Dissecting aneurysm of the ascending aorta as a late complication of the treatment of acquired defects of the aortic and mitral valves

A diffuse aneurysm of the ascending aorta was observed five months after prosthetic valve implantation in to mitral and aortic orifices because of the acquired valvular heart disease. The main factor predisposing to the formation of a false aneurysm was an infection of the endocardium and ascending aortal wall which were observed previously during cardiac surgery. The diagnosis, based on the clinical symptoms and non-invasive investigations, was later confirmed with aortography and intra-operatively.     

Method of devising a muscle pump for assisted circulation

The authors have proposed a model of the blood pump from the skeletal automuscles of the body for carrying out aortal counterpulsation under experimental conditions. The pump is run by means of direct electric stimulation of the muscle. Have demonstrated that it is possible in principle to design a completely implanted small system of aortal counterpulsation.     

Quantifying division of aortal smooth muscle cells in culture stimulated by 1,25(OH)2D3

Inhibitory effect of 1,25dihydroxycholecalciferol (1,25D₃ = calcitriol) in different cell type is well recognized but its promoting effect on vascular smooth muscle cells (SMCs) is poor established. Therefore, the aim of this study was to determine stimulatory effect of calcitriol on aortal SMCs proliferation in culture. We used the cell division analysis procedure based on the quantitative sequential halving of the stably incorporating fluorescent dye carboxyfluorescein diacetate succinimidyl ester (CFSE). This technique allowed the visualization of cycles of SMCs division by flow cytometry. Rat aortal SMCs were labeled with CFSE and cultured for up to 10 days with defined concentration of calcitriol in medium. Proliferative activity as the percentage of SMCs in different phases of the cell cycle using propidium iodide was determined. Apoptosis was assessed using Annexin-V/CFDA method. The results suggest that low concentrations of an active form of vitamin D—1,25dihydroxycholecalciferol applied in supraphysiological concentration of 10 nmol/l is a mitogenic factor for aortal SMCs. None of the applied concentrations of calcitriol caused apoptosis. The findings well support our morphological (LM) and ultrastructural (TEM and SEM) observations.     

Quantifying division of aortal smooth muscle cells in culture stimulated by 1,25(OH)2D3

Inhibitory effect of 1α,25dihydroxycholecalciferol (1,25D₃ = calcitriol) in different cell type is well recognized but its promoting effect on vascular smooth muscle cells (SMCs) is poor established. Therefore, the aim of this study was to determine stimulatory effect of calcitriol on aortal SMCs proliferation in culture. We used the cell division analysis procedure based on the quantitative sequential halving of the stably incorporating fluorescent dye carboxyfluorescein diacetate succinimidyl ester (CFSE). This technique allowed the visualization of cycles of SMCs division by flow cytometry. Rat aortal SMCs were labeled with CFSE and cultured for up to 10 days with defined concentration of calcitriol in medium. Proliferative activity as the percentage of SMCs in different phases of the cell cycle using propidium iodide was determined. Apoptosis was assessed using Annexin-V/CFDA method. The results suggest that low concentrations of an active form of vitamin D—1α,25dihydroxycholecalciferol applied in supraphysiological concentration of 10 nmol/l is a mitogenic factor for aortal SMCs. None of the applied concentrations of calcitriol caused apoptosis. The findings well support our morphological (LM) and ultrastructural (TEM and SEM) observations.     

Relaxant effects of oligopeptides isolated from the tracheal mucosa and pulmonary parenchyma on the smooth muscle of isolated rat trachea]

Relaxant effect of oligopeptides extracted from tracheal mucosa (PTM), lung parenchyma (PLP), aortal wall (PAW) and thymic gland (PTG) was investigated using acetylcholine-induced constriction of tracheal strips. Time of 50 percent relaxation of constricted strips treated with saline, atropine or peptides was measured. Both PTM and PLP in concentrations 10(-6)-10(-3) g/ml accelerated relaxation in dose-dependent manner, however this effect was less prominent compared with atropine. Relaxant effect of PTM was found using different parts of trachea (cervical of thoracal), indicating independence of PTM action of intramural ganglia which are present only in the thoracal part. PAW and PTG did not show any significant effect on relaxation time. These results suggest the presence of oligopeptides, capable to relax airways smooth muscle, in tracheal mucosa and lung parenchyma.     

Enhanced biotransformation of sitosterol to androstenedione by <Emphasis Type="Italic">Mycobacterium</Emphasis> sp. using cell wall permeabilizing antibiotics

Mycobacterial cell wall is rigid and offers a high resistance to the transport of sitosterol into cytosol. The effect of ethambutol, penicillin, polymixin and bacitracin on biotransformation of sitosterol to androstenedione by modification of cell wall permeability was examined. Drug sensitivity assay results established that bacitracin increased the permeability of the cell wall to hydrophobic compounds. Growth inhibitory study of bacitracin and rifamycin, individually as well as in combination showed that these two antibiotics act synergistically to reduce cell growth. A comparison of transmission electron micrograph results of the bacitracin-treated cells with untreated cells, revealed deformities caused in the cell wall structure by bacitracin treatment. These deformities increased the cell wall permeability and transport of sitosterol inside the cell, and thus enhanced androstenedione (AD) production. A maximum of 1.37, 1.44, 1.65 and 1.76 g AD per gram dry cell weight of mycobacterial cells was produced in the presence of ethambutol, penicillin, polymixin and bacitracin, respectively. Below the minimum inhibitory concentration, bacitracin can be used as potent enhancer of permeability of hydrophobic substances across the mycobacterial cell wall.     

Infection with Porphyromonas gingivalis Exacerbates Endothelial Injury in Obese Mice

Background

A number of studies have revealed a link between chronic periodontitis and cardiovascular disease in obese patients. However, there is little information about the influence of periodontitis-associated bacteria, Porphyromonas gingivalis (Pg), on pathogenesis of atherosclerosis in obesity.

Methods

In vivo experiment: C57BL/6J mice were fed with a high-fat diet (HFD) or normal chow diet (CD), as a control. Pg was infected from the pulp chamber. At 6 weeks post-infection, histological and immunohistochemical analysis of aortal tissues was performed. In vitro experiment: hTERT-immortalized human umbilical vein endothelial cells (HuhT1) were used to assess the effect of Pg/Pg-LPS on free fatty acid (FFA) induced endothelial cells apoptosis and regulation of cytokine gene expression.

Results

Weaker staining of CD31 and increased numbers of TUNEL positive cells in aortal tissue of HFD mice indicated endothelial injury. Pg infection exacerbated the endothelial injury. Immunohistochemically, Pg was detected deep in the smooth muscle of the aorta, and the number of Pg cells in the aortal wall was higher in HFD mice than in CD mice. Moreover, in vitro, FFA treatment induced apoptosis in HuhT1 cells and exposure to Pg-LPS increased this effect. In addition, Pg and Pg-LPS both attenuated cytokine production in HuhT1 cells stimulated by palmitate.

Conclusions

Dental infection of Pg may contribute to pathogenesis of atherosclerosis by accelerating FFA-induced endothelial injury.     

Age-dependent aluminum accumulation in the human aorta and cerebral artery

The purpose of this study was to determine the extent of aluminum (Al) accumulation in the human aorta and cerebral arteries. The Al contents in the aortae and in the cerebral arteries from 23 human subjects was determined by inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The subjects' age range was 45–99-yr-old; 15 of the subjects were males and 8 were females. Al was detected in twelve aortae and in six cerebral arteries, when the entire specimen was analyzed. Two specimens where Al was found in the cerebral arteries contained no Al in the aorta. No relationship to the subject's sex was found. When related to age, two groups were established. Group L (45–75 yr old) and group H (>75 yr old), which exhibited aortal Al concentrations of 33.3 and 72.7%, respectively. When the aortic wall was dissected into the tunica intima, media, and adventitia, Al was found mainly in the tunica media. In the aorta, significant relationships were found between Al and phosphorus (P) levels (r=0.801,p<0.01) and between Al and calcium (Ca) (r=0.661,p<0.05). We have concluded that Al accumulation is age-dependent and that it occurs both in the aorta and in the cerebral artery. In the aorta, accumulation occurs mainly in the tunica media. Both P and Ca appear to enhance aortal Al accumulation.     

Constitutional and age-related properties of the aortic isthmus

By means of micro- and macropreparation and morphometry methods in 200 corpses of children and adult persons, it has been stated that skeletotopy and syntopy of the aortal isthmus depends on the constitution of the person. Certain objective criteria have been elaborated for surgical approaches to the aortal isthmus. In little children, during early and first childhood, anterolateral thoracotomy should be performed in the III intercostal space; in persons with brachymorphose type of constitution--left-sided thoracotomy in the IV intercostal space; in persons with transitional and long-narrow thorax--left-sided thoracotomy in the V intercostal space with resection of the V rib.     

Induction of endothelial cell migration by proline analogs and its relevance to angiogenesis

The proline analogs cis-4-hydroxy-L-proline, 3,4-dehydro-L-proline, and 2-azetidinecarboxylic acid induced increases in the migration rate of retinal capillary endothelial cells, aortal endothelial cells, corneal endothelial cells, aortal smooth muscle cells, and retinal pericytes. cis-4-hydroxy-D-proline did not. The optimal concentration for migration induction by any of the active agents was approximately 10(-5) M. At higher concentrations (5 x 10(-4) M) migration was not induced or was inhibited. When tested by subcutaneous implant assays in rabbits, cis-4-hydroxy-L-proline and 2-azetidinecarboxylic acid consistently elicited a marked angiogenic response. Whereas these compounds are known to modulate collagen synthesis and secretion, the concentrations at which they are effective inducers of migration suggest that they may have a more specific target than general collagen synthesis.     

Studies on vascular permeability in hypertension: action of anthocyanosides

The initial phase of renal hypertension induced by ligature of the abdominal aorta was accompanied by a transient increase in vascular permeability. This permeability increase has not the same intensity in all parts of the organism: it is greater in the skin and in the aorta wall than in the brain vessels. Treatment of rats with a flavonoid-type drug (anthocyanosides of Vaccinium myrtillus) for 12 days before the induction of hypertension kept the blood-brain barrier permeability normal and limited the increase in vascular permeability in the skin and the aorta wall. As previously demonstrated, the collagens of the blood vessel walls play an important role in the control of vascular permeability. Interaction of these collagens with the drug may be partly responsible for the protection against the permeability-increasing action of hypertension observed in the treated animals.     

Transmural Intestinal Wall Permeability in Severe Ischemia after Enteral Protease Inhibition

In intestinal ischemia, inflammatory mediators in the small intestine''s lumen such as food byproducts, bacteria, and digestive enzymes leak into the peritoneal space, lymph, and circulation, but the mechanisms by which the intestinal wall permeability initially increases are not well defined. We hypothesize that wall protease activity (independent of luminal proteases) and apoptosis contribute to the increased transmural permeability of the intestine''s wall in an acutely ischemic small intestine. To model intestinal ischemia, the proximal jejunum to the distal ileum in the rat was excised, the lumen was rapidly flushed with saline to remove luminal contents, sectioned into equal length segments, and filled with a tracer (fluorescein) in saline, glucose, or protease inhibitors. The transmural fluorescein transport was determined over 2 hours. Villi structure and epithelial junctional proteins were analyzed. After ischemia, there was increased transmural permeability, loss of villi structure, and destruction of epithelial proteins. Supplementation with luminal glucose preserved the epithelium and significantly attenuated permeability and villi damage. Matrix metalloproteinase (MMP) inhibitors (doxycycline, GM 6001), and serine protease inhibitor (tranexamic acid) in the lumen, significantly reduced the fluorescein transport compared to saline for 90 min of ischemia. Based on these results, we tested in an in-vivo model of hemorrhagic shock (90 min 30 mmHg, 3 hours observation) for intestinal lesion formation. Single enteral interventions (saline, glucose, tranexamic acid) did not prevent intestinal lesions, while the combination of enteral glucose and tranexamic acid prevented lesion formation after hemorrhagic shock. The results suggest that apoptotic and protease mediated breakdown cause increased permeability and damage to the intestinal wall. Metabolic support in the lumen of an ischemic intestine with glucose reduces the transport from the lumen across the wall and enteral proteolytic inhibition attenuates tissue breakdown. These combined interventions ameliorate lesion formation in the small intestine after hemorrhagic shock.     

Computational analysis of coupled blood-wall arterial LDL transport

The transport of macromolecules, such as low density lipoproteins (LDLs), across the artery wall and their accumulation in the wall is a key step in atherogenesis. Our objective was to model fluid flow within both the lumen and wall of a constricted, axisymmetric tube simulating a stenosed artery, and to then use this flow pattern to study LDL mass transport from the blood to the artery wall. Coupled analysis of lumenal blood flow and transmural fluid flow was achieved through the solution of Brinkman's model, which is an extension of the Navier-Stokes equations for porous media. This coupled approach offers advantages over traditional analyses of this problem, which have used possibly unrealistic boundary conditions at the blood-wall interface; instead, we prescribe a more natural pressure boundary condition at the adventitial vasa vasorum, and allow variations in wall permeability due to the occurrence of plaque. Numerical complications due to the convection dominated mass transport process (low LDL diffusivity) are handled by the streamline upwind/Petrov-Galerkin (SUPG) finite element method. This new fluid-plus-porous-wall method was implemented for conditions typical of LDL transport in a stenosed artery with a 75 percent area reduction (Peclet number=2 x 10(8)). The results show an elevated LDL concentration at the downstream side of the stenosis. For the higher Darcian wall permeability thought to occur in regions containing atheromatous lesions, this leads to an increased transendothelial LDL flux downstream of the stenosis. Increased transmural filtration in such regions, when coupled with a concentration-dependent endothelial permeability to LDL, could be an important contributor to LDL infiltration into the arterial wall. Experimental work is needed to confirm these results.     

Leukocyte adhesion and microvessel permeability

To investigate the direct effect of leukocyte adherence to microvessel walls on microvessel permeability, we developed a method to measure changes in hydraulic conductivity (L(p)) before and after leukocyte adhesion in individually perfused venular microvessels in frog mesentery. In 19 microvessels that were initially free of leukocyte sticking or rolling along the vessel wall, control L(p) was measured first with Ringer-albumin perfusate. Blood flow was then restored in each vessel with a reduced flow rate in the range of 30-116 microm/s to facilitate leukocyte adhesion. Each vessel was recannulated in 45 min. The mean number of leukocytes adhering to the vessel wall was 237 +/- 22 leukocytes/mm(2). At the same time, L(p) increased to 4.7 +/- 0.5 times the control value. Superfusion of isoproterenol (10 microM) after leukocyte adhesion brought the increased L(p) back to 1.1 +/- 0.2 times the control in 5-10 min (n = 9). Superfusing isoproterenol before leukocyte adhesion prevented the increase in L(p) (n = 6). However, the number of leukocytes adhering to the vessel wall was not significantly affected. These results demonstrated that leukocyte adhesion caused an increase in microvessel permeability that could be prevented or restored by increasing cAMP levels in endothelial cells using isoproterenol. Thus cAMP-dependent mechanisms that regulate inflammatory agent-induced increases in permeability also modulate leukocyte adhesion-induced increases in permeability but act independently of mechanisms that regulate leukocyte adhesion to the microvessel wall. Application of ketotifen, a mast cell stabilizer, and desferrioxamine mesylate, an iron-chelating reagent, attenuated the increase in L(p) induced by leukocyte adhesion, suggesting the involvement of oxidants and the activation of mast cells in leukocyte adhesion-induced permeability increase. Furthermore, with the use of an in vivo silver stain technique, the locations of the adherent leukocytes on the microvessel wall were identified quantitatively in intact microvessels.     

Effects of skim milk, skim milk yogurt, orotic acid, and uric acid on lipid metabolism in rats

The effects of feeding two milk products (skim milk and skim milk yogurt) and two proposed hypocholesterolemic factors (orotic acid and uric acid) on serum cholesterol (HDL, LDL, total, HDL/Total and HDL/LDL), liver lipids (total liver lipids and liver cholesterol), and aortal cholesterol were studied. Ten groups, of nine rats each, were fed isocaloric Chow-based diets containing water, 45% skim milk (SM), 45% skim milk yogurt (SMY), and 0.0025% orotic acid (OA) or 0.001% uric acid (UA), without or with cholesterol. The SM diet (with cholesterol) resulted not only in lower total cholesterol (P < 0.10), LDL cholesterol (P < 0.05), aortal cholesterol (P < 0.01), and liver cholesterol (P < 0.10), but also in increased HDL (P < 0.05) and HDL/LDL (P < 0.10) cholesterol ratio. The SMY diet, on the other hand, resulted in lowered total serum cholesterol (P < 0.05) and aortal cholesterol (P < 0.01) and in higher LDL (P < 0.05) cholesterol. The hypocholesterolemic effects were more marked for SM than for SMY. Addition of OA and UA to diets increased serum cholesterol, LDL cholesterol, and total liver lipids; the OA diet also increased liver cholesterol. Neither OA nor UA alone was the factor responsible for the hypocholesterolemic effects seen with SM and SMY feeding.     

Evaluation of oxygen permeability of gas vesicles from cyanobacterium Anabaena flos-aquae

The enhancement of oxygen permeability in aqueous medium by addition of cyanobacterial gas vesicles (GVs) has been examined. The GVs were isolated from cultures of Anabaena flos-aquae that had been cultivated in photobioreactors and harvested by dark flotation. Prior to the permeability experiments, the collected GVs were treated with glutaraldehyde for improved stability. Measurements of oxygen permeability were made with a polarographic oxygen electrode in suspensions of various GV volume fractions (0-2.1%). The experimental results were compared with the values predicted theoretically (Fricke's equation) assuming different permeability through the GVs (PmGV), ranging from 0 to 8.30 x 10(-4) mol m-1 atm-1 s-1. The former corresponded to impermeable vesicles, the latter to air at 22 degrees C as if there were no vesicle wall. The best-fit value of PmGV was 9.9 x 10(-7) mol m-1 atm-1 s-1, ca. 36-fold higher than that in water. GVs were therefore very permeable to oxygen. However, the value was much lower than that predicted for air, implying the existence of wall resistance.     

Physical organization of lipids in the cell wall of Mycobacterium chelonae

Mycobacterial cell wall functions as an effective permeability barrier, making these bacteria resistant to most antibacterial agents. It has been assumed that this low permeability was due to the presence of a large amount of unusual lipids in the cell wall, but it was not known how these lipids are able to produce such an exceptional barrier. We report here the first experimental evidence on the physical arrangement of these lipids based on X-ray diffraction studies of purified Mycobacterium chelonae cell wall, a result suggesting that the hydrocarbon chains of the cell-wall lipids are arranged predominantly in a direction perpendicular to the cell wall surface, probably producing an asymmetric bilayer structure.     

Two-dimensional maps of short-term albumin uptake by the immature and mature rabbit aortic wall around branch points

In children, aortic lipid deposition develops in triangular regions of the wall downstream of branch points, whilst in adults these regions are particularly free of disease. Comparable age-related patterns occur in rabbit aortas. They may be explained by patterns of wall permeability to circulating macromolecules: along the longitudinal midline through branches, permeability is greater downstream than upstream in immature rabbits, but is greater upstream at later ages. Here we have mapped permeability in detail around such branches, not just along the midline. Short-term uptake of rhodamine-labeled albumin, measured using digital imaging fluorescence microscopy of serial sections, was greatest in an approximately triangular region downstream of immature branches, but in mature animals it was greater upstream, particularly away from the midline, and in streaks to the side of branches. Hence the maps are consistent with earlier permeability data and closely resemble the patterns of disease.     

Early changes in coronary artery wall structure detected by microcomputed tomography in experimental hypercholesterolemia

Changes in the structure of the artery wall commence shortly after exposure to cardiovascular risk factors, such as hypercholesterolemia (HC), but may be difficult to detect. The ability to study vascular wall structure could be helpful in evaluation of the factors that instigate atherosclerosis and its pathomechanisms. The present study tested the hypothesis that early morphological changes in coronary arteries of hypercholesterolemic (HC) pigs can be detected using the novel X-ray contrast agent OsO(4) and three-dimensional micro-computed tomography (CT). Two groups of pigs were studied after they were fed a normal or an HC (2% cholesterol) diet for 12 wk. Hearts were harvested, coronary arteries were injected with 1% OsO(4) solution, and cardiac samples (6-mum-thick) were scanned by micro-CT. Layers of the epicardial coronary artery wall, early lesions, and perivascular OsO(4) accumulation were determined. Leakage of OsO(4) from myocardial microvessels was used to assess vascular permeability, which was correlated with immunoreactivity of vascular endothelial growth factor in corresponding histological cross sections. OsO(4) enhanced the visualization of coronary artery wall layers and facilitated detection of early lesions in HC in longitudinal tomographic sections of vascular segments. Increased density of perivascular OsO(4) in HC was correlated with increased vascular endothelial growth factor expression and suggested increased microvascular permeability. The use of OsO(4) as a contrast agent in micro-CT allows three-dimensional visualization of coronary artery wall structure, early lesion formation, and changes in vascular permeability. Therefore, this technique can be a useful tool in atherosclerosis research.     

Capsule walls as barriers to oxygen availability: Implications for the development of brooded embryos by the estuarine gastropod Crepipatella dilatata (Calyptraeidae)

Encapsulation of developing embryos imposes potential restrictions, because the capsule wall must allow for adequate inward diffusion of oxygen and for increased diffusion of oxygen as metabolic demand increases with continued development. Samples of egg capsules from the gastropod Crepipatella dilatata were used to document surface characteristics, composition of the different capsule wall layers, and alterations in wall thickness during development. The diffusion coefficient and capsule wall permeability were determined experimentally for capsules containing embryos at different developmental stages. We also determined oxygen consumption rates for various embryonic stages and for nurse eggs, which provide food for embryos during development. The capsule wall of C. dilatata possesses 2 differentiated layers: the external capsular wall (ECW) and the internal capsular wall (ICW). The ECW is compact and fibrous, features that remain invariable during development, and lacks surface features that might make some portions of the capsule wall more permeable to oxygen than others. On the other hand, the ICW is initially spongy and thick, but significantly decreases in thickness over time, particularly before the embryos begin feeding on nurse eggs. Although the capsule wall is a serious barrier to diffusion, permeability to oxygen increases over time by 112% due to the dramatic thinning of the inner capsule wall layer. Nurse eggs consume oxygen but at very low rates, supporting the idea that they correspond to living embryonic cells that have stopped their development. Respiration measurements indicated that embryos are initially supplied with enough oxygen within the egg capsules to carry out the activities characteristic of embryogenesis, even though the capsular walls show their maximum thickness and lowest permeability at this time. However, as the embryo develops its velum and becomes more active, capsule wall thickness decreases and capsule permeability to oxygen increases. Correspondingly, the oxygen demands of metamorphosed but still encapsulated specimens are approximately 135% higher than those of pre-metamorphosed sibling embryos.