[Dental care to the Israeli Defense Forces' fighters].

The combat soldiers of the Israeli Defense Forces (IDF) get comprehensive dental care. The service of a combat soldier in the IDF can be divided into two periods: the period of training that includes basic training and advanced training lasting six to eight months, followed by a period of operational activity within the framework of the battalions. Throughout his service, the combat soldier is exposed to dental disease including dental caries, periodontal disease and dental trauma attributed to his terms of service with low availability to maintain adequate oral hygiene in high intensity training. There is no available data as to the dental status of new recruits. This information is needed in order to determine the level of oral and dental health among combatsoldiers in order to guarantee operational continuity. Every recruit undergoes a full dental examination in order to determine his level of oral and dental health. From this point on, dental treatment is offered and performed according to the level of oral and dental health, in order to treat the most severe levels. The dental treatment is carried out so that throughout his service, the combat soldier is summoned to various dental clinics: the base unit training clinic, clinics serving the Brigades and experts clinics. All the factors mentioned above, are designed to help increase the provision of therapy, and lead to an increase in the number of fighters who receive comprehensive dental care.

The reorganization of microfilaments, centrosomes, and microtubules during in vitro small wound reendothelialization.

The repair of small endothelial wounds is an important process by which endothelial cells maintain endothelial integrity. An in vitro wound model system was used in which precise wounds were made in a confluent endothelial monolayer. The repair process was observed by time-lapse cinemicrophotography. Using fluorescence and immunofluorescence microscopy, the cellular morphological events were correlated with the localization and distribution of actin microfilament bundles and vinculin plaques, and centrosomes and their associated microtubules. Single to four-cell wounds underwent closure by cell spreading while wounds seven to nine cells in size closed by initially spreading which was then followed at approximately 1 h after wounding by cell migration. These two processes showed different cytoskeletal patterns. Cell spreading occurred independent of centrosome location. However, centrosome redistribution to the front of the cell occurred as the cells began to elongate and migrate. While the peripheral actin microfilament bundles (i.e., the dense peripheral band) remained intact during cell spreading, they broke down during migration and were associated with a reduction in peripheral vinculin plaque staining. Thus, the major events characterizing the closure of endothelial wounds were precise in nature, followed a specific sequence, and were associated with specific cytoskeletal patterns which most likely were important in maintaining directionality of migration and reducing the adhesion of the cells to their neighbors within the monolayer.

Microtubule-organizing centers and cell migration: effect of inhibition of migration and microtubule disruption in endothelial cells.

We have previously shown that microtubule-organizing centers (MTOC's) become preferentially oriented towards the leading edge of migrating endothelial cells (EC's) at the margin of an experimentally induced wound made in a confluent EC monolayer. To learn more about the mechanism responsible for the reorientation of MTOC's and to determine whether a similar reorientation takes place when cell migration is inhibited, we incubated the wounded cultures with colcemid (C) and cytochalasin B (CB), which disrupt microtubules (MT's) and microfilaments (MF's), respectively. The results obtained showed that the MTOC reorientation can occur independent of cell migration since MTOC's reoriented preferentially toward the wound edge in the CB-treated cultures, even though forward migration of the EC was inhibited. In addition, the MTOC reorientation is inhibited by C, indicating that it requires an intact system of MT's and/or other intracellular structures whose distribution is dependent on that of MT's.

Distribution of microtubule organizing centers in migrating sheets of endothelial cells.

This study was designed to investigate the relationship between the position of the microtubule organizing center (MTOC) and the direction of migration of a sheet of endothelial cells (EC). Using immunofluorescence and phase microscopy the MTOC's of migrating EC were visualized as the cells moved into an in vitro experimental wound produced by mechanical denudation of part of a confluent monolayer culture. Although the MTOC's in nonmigrating EC were randomly positioned in relation to the nucleus, in migrating cells the position of the MTOC's changed so that 80% of the cells had the MTOC positioned in front of the nucleus toward the direction of movement of the endothelial sheet. This repositioning of the MTOC occurred within the first 4 h after wounding and was associated with the beginning of migration of EC's into the wounded area as seen by time-lapse cinemicrophotography. These studies focus attention on the MTOC as a cytoskeletal structure that may play a role in determining the direction of cell movement.

Transient and steady-state effects of shear stress on endothelial cell adherens junctions.

Endothelial cells exhibit profound changes in cell shape in response to altered shear stress that may require disassembly/reassembly of adherens junction protein complexes that mediate cell-cell adhesion. To test this hypothesis, we exposed confluent porcine aortic endothelial cells to 15 dyne/cm(2) of shear stress for 0, 8.5, 24, or 48 hours, using a parallel plate flow chamber. Cells were fixed and stained with antibodies to vascular endothelial (VE) cadherin, alpha-catenin, beta-catenin, or plakoglobin. Under static conditions, staining for all proteins was intense and peripheral, forming a nearly continuous band around the cells at cell-cell junctions. After 8.5 hours of shear stress, staining was punctate and occurred only at sites of continuous cell attachment. After 24 or 48 hours of shear, staining for VE-cadherin, alpha-catenin, and beta-catenin was intense and peripheral, forming a band of "dashes" (adherens plaques) that colocalized with the ends of stress fibers that inserted along the lateral membranes of cells. Staining for plakoglobin was not observed after 24 hours of shear stress, but returned after 48 hours. Western blot analysis indicated that protein levels of VE-cadherin, alpha-catenin, and plakoglobin decreased, whereas beta-catenin levels increased after 8.5 hours of shear stress. As cell shape change reached completion (24 to 48 hours), all protein levels were upregulated except for plakoglobin, which remained below control levels. The partial disassembly of adherens junctions we have observed during shear induced changes in endothelial cell shape may have important implications for control of the endothelial permeability barrier and other aspects of endothelial cell function.

In vitro high resolution intravascular imaging in muscular and elastic arteries.

High resolution (125-microns lateral, 55-microns axial) images of 16 muscular (femoral) and 15 elastic (common carotid) human arteries were made in vitro with use of a prototype 45-MHz intravascular imaging system. Four distinct regions of scattering, excluding plaque, were identified in the ultrasound images corresponding histologically to the adventitia, media, thickened intima and elastic laminae, both internal and external. Arterial samples imaged under pressure and in a collapsed state underwent dimensional changes but exhibited similar levels of backscatter amplitude. All the elastic arteries displayed a prominent echogenic media, whereas all the muscular arteries displayed an echolucent media. Scattering from the internal elastic lamina in muscular arteries provided an excellent landmark for defining the location and extent of intimal thickening or plaque. In elastic arteries the internal elastic lamina could not be distinguished from the echogenic media; consequently, the boundary between the media and intimal layer was indistinct. Differences in the relative concentration and organization of collagen and elastin were found to provide a consistent explanation for the differences in scattering that were observed between individual layers within an artery as well as between muscular and elastic arteries.

Microtubules regulate aortic endothelial cell actin microfilament reorganization in intact and repairing monolayers.

To understand the role of microtubules and microfilaments in regulating endothelial monolayer integrity and repair, and since microtubules and microfilaments show some co-alignment in endothelial cells, we tested the hypothesis that microtubules organize microfilament distribution. Disruption of microtubules with colchicine in resting confluent aortic endothelial monolayers resulted in disruption of microfilament distribution with a loss of dense peripheral bands, an increase in actin microfilament bundles, and an associated increase of focal adhesion proteins at the periphery of the cells. However, when microfilaments were disrupted with cytochalasin B, microtubule distribution did not change. During the early stages of wound repair of aortic endothelial monolayers, microtubules and microfilaments undergo a sequential series of changes in distribution prior to cell migration. They are initially distributed randomly relative to the wound edge, then align parallel to the wound edge and then elongate perpendicular to the wound edge. When microtubules in wounded cultures were disrupted, dense peripheral bands and lamellipodia formation were lost with increases in central stress fibers. However, following microfilament disruption, microtubule redistribution was not disrupted and the microtubules elongated perpendicular to the wound edge similar to non-treated cultures. Microtubules may organize independently of microfilaments while microfilaments require microtubules to maintain normal organization in confluent and repairing aortic endothelial monolayers.

Field Evaluation of a New Sequential Sampling Technique for Determining Apple Scab "Risk".

Most fungicide sprays applied to apple orchards in the New England states are targeted at the management of apple scab. Researchers have developed action thresholds that aid in decision-making on whether early spring fungicide applications could be eliminated without a significant increase in the incidence of fruit scab at harvest. To facilitate grower adoption of these thresholds, a simplified, sequential sampling technique in autumn to determine the "scab risk" of an orchard for the following spring was proposed in the scientific literature. However, this technique had not been evaluated in the field. In autumn 1999, 2000, and 2001, orchards were evaluated using the new sequential sampling technique to determine scab risk. Risk ratings were compared with those obtained by the original, nonsequential procedure in each orchard. Data also were examined using a simulation sequential sampling computer program to determine whether or not risk ratings would change if different trees or shoots were used. In two of the assessed orchards, "delayed-spray" experiments involving two treatments (a delayed-spray and full-spray treatment) were conducted in 2000 and 2001. Delayed-spray replicates were to receive no fungicide sprays until after the third primary infection period (but before the fourth) or until the pink stage of bud development, whichever came first; full-spray replicates received fungicide sprays starting at the green-tip stage of bud development. The sequential sampling technique provided scab-risk ratings consistent with the original, nonsequential procedure, at potentially significant time savings. Also, following the delayed-spray strategy in low-risk orchards did not result in significant differences in fruit scab at harvest compared with initiating spraying at the green-tip phenological bud stage.

The reorganization of cytoskeletal fibre systems in spreading porcine endothelial cells in cultures.

Porcine aortic endothelial cells spreading on a glass substrate undergo characteristic changes in shape which can be classified into four distinct stages. To study the role of the cytoskeleton in cell spreading, we have examined the distribution of microtubules (MT), microfilaments (MF), and intermediate filaments (IF) at each of these stages by using immunofluorescence and antisera specific for tubulin, tropomyosin, myosin, and vimentin. The small round Stage I cells showed diffuse staining with four antisera. In the more flattened spreading Stage II cells, MT and IF were first observed in the perinuclear region while fibres straining positively for tropomyosin and myosin were first seen along the cell margin. Later the MT began to radiate out in all directions from the perinuclear region while the IF became localized in a region on one side of the nucleus. In the very flat Stage III cells with a circular outline, additional MT could be seen along and parallel to cell margin while the IF emanating from the perinuclear region and the tropomyosin and myosin positive fibres became concentrically distributed around the nucleus. In the very flat asymmetric Stage IV cells, both the MT and IF radiated out from the perinuclear region towards the cell periphery while most of the tropomyosin and myosin-positive fibres became reorganized so that they ran parallel to the edges of the cell. In addition several loci from which a number of the tropomyosin and myosin-containing fibres radiated also appeared at this stage. These results indicate that during spreading each of the three major fibre systems undergo extensive and specific reorganization which is well coordinated with changes in cell shape.

Concentric hemorrhagic necrosis of the myocardium. A morphological and clinical study.

Froty-nine cases of concentric hemorrhagic necrosis of the left ventricular myocardium were reviewed in a series of 97 autopsy studies in patients subjected to cardiopulmonary bypass for various types of cardiac surgery. The gross and microscopic findings were analyzed in order to define the morphologic evolution of the lesion. The extent of involvement was graded by gross examination of serial transverse sections of the heart. Microscopically there were five major histologic changes, probably representing the sequential evolution of the lesion, i.e., contraction bands, subendocardial hemorrhages, coagulative necrosis, healing by granulation tissue, and fibrosis. The location of the lesion conincided with the vulnerable region of the microcirculation. Owing to the implementation of new surgical techniques, the cases were subdivided into two groups, one covering the period from 1963 to 1970 and the other , 1971 to 1974. Concentric hemorrhagic necrosis was less frequent in the more recent group, but when it was present it was more pronounced in the individual heart. The lesion in the earlier group was milder but demonstrated a higher incidence of platelet microthrombi in the heart. In the recent cases concentric hemorrhagic necrosis tended to be more diffuse in aortocoronary bypass than in valvular replacement surgery. We discuss one possible explanation for the development of this lesion, i.e., transient hypoxemia occurring at the time of cardiopulmonary bypass, followed by reperfusion and accelerated necrosis with hemorrhage.

Understanding the role of the cytoskeleton in the complex regulation of the endothelial repair.

Actin microfilaments and microtubules are important cytoskeletal proteins that regulate endothelial repair through alterations in cell shape and through regulation of cell migration following wounding of the endothelium. Upstream pathways have been identified in the regulation of actin and microtubule organization, especially small GTPases. Recently, there have been numerous proteins suggested to be capable of regulating interaction between microtubules and microfilaments to mediate microtubule regulation of endothelial repair, an important process in limiting injury to the artery wall and in reducing the extent of arterial disease. If disrupted, a rapid repair mechanism is important in reestablishing the integrity of the endothelium in order to reestablish its function as a macromolecular barrier, a thromboresistant surface, and a biologically active tissue. Strategies to improve repair should alter the pathobiology of the atherosclerotic plaque and thus improve the prognosis of patients with atherosclerosis.

Microtubule-actin interactions may regulate endothelial integrity and repair.

An important mechanism for the initiation and progression of atherosclerosis is the loss of endothelial integrity, which is required for normal blood vessel function. The important components of the endothelial cell cytoskeleton system that regulate endothelial integrity include actin microfilaments and microtubules, which are both associated with protein complexes that regulate cell-cell and cell-substratum adhesion. To date, studies have shown that microfilaments are essential in maintaining the structural integrity of the endothelium while microtubules regulate the directional cell migration during repair. When microtubules are disrupted at the onset of wounding, neither centrosome reorientation, which is essential for efficient endothelial cell wound repair, nor cell migration occurs. Disruption of microfilaments is also associated with inefficient endothelial cell migration and repair. How then might these systems be associated with one another? Linker proteins, which may facilitate interaction between microtubules and actin microfilaments, have recently been identified in nonendothelial systems. It is likely that microtubule-microfilament interactions are important in the complex regulation of endothelial integrity and repair especially as they relate to atherosclerotic plaque formation.

Porcine coronary artery organ culture: A model for the study of angioplasty injury.

The pathogenesis of coronary artery restenosis following angioplasty is not well understood. In order to carry out studies on the pathogenesis of restenosis, we developed and characterized an organ culture system using the porcine epicardial left anterior descending and circumflex coronary arteries. In nonangioplasty cultures at two weeks there was neointimal formation with intimal smooth muscle cells present within a loose matrix. All the neointimal cells beneath the endothelium stained positive for smooth muscle cell actin with α-SM1 antibody. Smooth muscle cell proliferation was maximum between four and eight days. Angioplasty, carried out by local balloon inflation at the onset of culture, resulted in an augmentation of the neointimal thickness and a further increase in smooth muscle cell proliferation. Endothelial cells, however, were absent from the angioplasty site, having been damaged and lost at the time of angioplasty. Because there is a response to angioplasty in this organ culture model, it will be a useful way of studying many of the factors likely to be important in the regulation of restenosis following angioplasty.

Analysis of atherosclerotic plaques obtained by coronary atherectomy: Foam cells correlated positively with subsequent restenosis.

Restenosis following coronary intervention is a complex process the mechanisms of which remains mostly unknown. Tissue obtained by atherectomy is an important means to study restenosis. Previous studies on atherectomy-retrieved tissue have not identified histologic features that correlate with restenosis. We performed an histopathologic evaluation on atherosclerotic plaque tissue obtained by atherectomy from 58 patients, all of whom had a 6-month angiographic follow-up. We identified macrophages and lymphocytes and localized tumor necrosis factor-α expression in the tissue by immunohistochemistry. Histopathology was correlated with late angiographic outcomes. Of 10 histologic features evaluated in the plaque tissue, only the presence of foam cells, identified in paraffin sections, correlated positively with restenosis (p = 0.04). Immunohistochemistry showed that macrophages (p = .07), tumor necrosis factor-α (p = .07), and lymphocytes (p = .14) were more prominent, but not significantly so, in lesions from patients with foam cells and restenosis than in lesions from patients without foam cells or restenosis. Thus the presence of foam cells in primary lesions obtained by atherectomy as identified in paraffin-embedded tissue appears to be a marker for restenosis.

Histological and immunohistochemical characteristics of eccentric coronary artery lesions retrieved by atherectomy from cardiac transplant recipients.

The lesions of cardiac allograft vasculopathy are thought to be strongly related to an immune inflammatory process. Little is known about the biology of these eccentric lesions. However, transplant patients may present with focal disease. Coronary atherectomy provides a unique opportunity to study these clinically relevant lesions in surviving transplant patients. In this series we characterized the features of four lesions (two restenotic and two primary) from three cardiac transplant recipients who underwent coronary atherectomy. The histologic characteristics of the lesions were analyzed and immunohistochemistry was used to assess qualitatively the presence of specific markers of inflammation and the extracellular matrix component fibronectin. Histology showed cholesterol clefts, calcium deposits, and foam cells with low to moderate cellularity and moderate to high fibrosis. Interleukin (IL)-1ß was present in two lesions, but tumor necrosis factor (TNF)-α was absent. The adhesion molecules intercellular adhesion molecule (ICAM)-1 and vascular cellular adhesion molecule (VCAM)-1 and the integrins α5ß1 and α4 were present in all lesions. There was mild to moderate accumulation of fibronectin. Thus, atheroscleroticlike features were present with only low to moderate degrees of immune inflammation. Our findings suggest that eccentric focal plaques in cardiac allograft vasculopathy are less likely to be primarily related to a prominent immune inflammatory process and are similar to atherosclerosis. We speculate that these eccentric lesions that resemble atherosclerosis may be more related to the conventional risk factors for coronary artery disease frequently seen in this population.

Systemic and nontraditional markers of endothelial dysfunction.

Endothelial cells control the balance between a number of opposing biological processes. Injury to these cells leads to a shift in this delicate balance; the resultant endothelial dysfunction ultimately leads to atherosclerotic disease. Specific markers of endothelial dysfunction can be used to detect and monitor the progression of atherosclerosis; they can also be used to study the pathogenesis of disease. Specific markers may be indicative of a particular stage in the pathogenesis of disease. By using a rigorous screening process, various markers of endothelial dysfunction can be identified. Common markers of endothelial dysfunction that are used in clinical studies are vascular cell adhesion molecule-1, intracellular adhesion molecule-1 and fibrinogen.

Review of antiplatelet drug use in preventing restenosis following percutaneous transluminal coronary angioplasty.

Although percutaneous transluminal coronary angioplasty is a widely accepted form of therapy for coronary artery disease, there is a 30% restenosis rate associated with it. The pathobiological processes that are triggered following coronary angioplasty are related to platelet-vessel wall interactions, coagulation, endothelial injury and smooth muscle cell modulation and proliferation. These events are reviewed with respect to the role of platelets and the products they release at the site of endothelial injury. Various families of antiplatelet drugs are discussed with regard to the rationale for their use and the results reported in patients undergoing percutaneous transluminal coronary angioplasty. The major conclusion is that a variety of processes are likely to be responsible for restenosis. Acetylsalicylic acid has been shown to be effective in reducing cardiovascular disease conditions associated with thrombosis and may effect reductions in restenosis through its inhibition of this process. Current pharmacologic regimens do not significantly reduce the incidence of smooth muscle cell proliferation, an important feature of long term stenosis. The role of new, more specific antiplatelet drugs as well as innovations in instrumental technology may hold future promise in reducing rates of restenosis.

Cell biology of valvular interstitial cells.

OBJECTIVE: To review the cell biology of the interstitial cells of heart valves. While studying the function of interstitial cells of heart valves, the authors observed that interstitial cells from porcine mitral valve have mixed phenotypic expression. DATA SOURCE: English-language literature from 1985-95 that discussed the cell biology of heart valve interstitial cells, including their structural and functional characteristics. RESULTS: Morphologically, heart valve interstitial cells have characteristics of both fibroblasts and smooth muscle cells. It is not clear, however, whether these cells represent a single (myofibroblast) cell type or whether there are two populations of cells within the valve. This review summarizes reports of the structural and functional characteristics of heart valve interstitial cells including ultrastructure, cell junctions, smooth muscle cell markers, cell growth, role in wound repair and contractility. CONCLUSIONS: Vascular interstitial cells play an important role in both normal and diseased valves. Our understanding of the heterogeneity of valvular interstitial cells is incomplete; however, this heterogeneity allows for multiple functions to be carried out including cell-cell communication, matrix secretion, wound repair and contractility. Future studies are needed to focus on the regulation of cellular heterogeneity as it relates to valve structure and function in health and disease.

Angiogenesis in atherosclerosis.

This article reviews studies on the structure, complications and pathogenesis of angiogenesis in atherosclerotic plaques. Although important, this topic has not been studied extensively; the authors present a review of the important information available in the literature. Since angiogenesis has profound clinical complications, the focus is on data which provided information to understand the nature of the vascular structures involved and the sequence of events which led to the initiation and growth of these small vessels in the plaque. This review indicates that it is most likely that the capillaries that first form arise from the vasa vasorum. Since the cell biology literature suggests that angiogenesis is regulated by angiogenic factors which stimulate vascular cell migration and proliferation, the known role of several growth factors and inhibitors is reviewed. It is likely that a complex interaction in the atherosclerotic vessel wall results in angiogenesis, and that further study with purified growth factors and other substances is needed to clarify the pathogenesis of this important biological process.

Ventricular preexcitation syndrome. Accessory left atrioventricular connection and rhabdomyomatous myocardial fibers.

A necropsy study of the heart of a 16-year-old girl with ventricular preexcitation syndrome and supraventricular tachycardia showed an accessory left atrioventricular connection partially within the mitral valve. Both the accessory pathway and the ventricular musculature showed multiple foci of cardiac muscle fibers with rhabdomyomatous features having the characteristic appearance of rhabdomyomatosis. The case is discussed in the context of a literature review of necropsy findings in cases of ventricular preexcitation.