Biomedical subjects
Publications and source records attributed to L Maximilian Buja.
We report a case of ascending and transverse aortic arch aneurysm repair with aortic valve replacement in a patient with MAGIC syndrome (mouth and genital ulcers with inflamed cartilage), the unusual setting of both Behçet's disease and relapsing polychondritis.
Severe burn causes immunosuppression, and the eschar remains a perfect culture medium for microbial growth. The resulting sepsis is a common complication of burns with a high mortality. The skin produces a number of molecules including antimicrobial peptides (AMPs) that act in the first line of host defense. Previous studies from our laboratory suggested decreased expression of human beta-defensin-2 (HBD-2) in burned wounds. Here, we have expanded our work by identifying HBD-1, HBD-2, HBD-3 and human neutrophil peptide (HNP) in normal and burn skin samples using fluorescence deconvolution microscopy. In normal skin, HBD-1 was localized to the perinuclear region of keratinocytes, while HBD-2 was seen primarily in the stratum basale of the epidermis. HBD-3 was found in dendritic cells of the stratum spinosum. HNP was distributed in a somewhat random pattern in the papillary dermis. In burned skin, in which the epidermis had been destroyed or disrupted, the presence of HBD-1 was localized to dermal glandular structures and hair shafts. HBD-2 was found in both the upper portions of the remaining keratin layers, and localized to lower, f-actin containing, acini-like structures, a pattern also evident with HBD-3. We conclude that although the upper layers of skin are destroyed and disrupted by burn, cells in the lower portions of the skin demonstrate an ability to synthesize most of the AMPs, thereby maintaining some barrier against infection. The results of these studies further contribute to an understanding of the role of AMPs in the pathophysiology of cutaneous burn and the possibility of using these sites for upregulation of AMP synthesis in the prevention of burn sepsis.
OBJECTIVE: The objective of this study was to observe the effects of cell culture on cellular polarity in cardiomyocytes as influenced by cytoskeletal proteins. METHODS: Cardiomyocytes from adult and neonatal rats were isolated and grown on 2 different extracellular matrices--laminin and a complex, fibroblast-derived extracellular matrix, cardiogel. The location of a number of proteins was visualized by means of fluorescence deconvolution microscopy, using specific fluorescent probes for alpha-adrenergic receptors, beta-adrenergic receptors, the sarcolemmal L-type calcium channel, and the sodium + potassium adenosine triphosphatase pump protein. Intracellular migration of these proteins during the first 4 days of culture was followed and microscopic stacked images were reconstructed. A fluorescein isothiocyanate-labeled probe for actin was used to ensure that cardiomyocytes were being examined, based on protein patterns. RESULTS: We examined 2 types of myocyte: freshly isolated neonates and cultured adult cardiomyocytes that undergo dedifferentiation. Initial, perinuclear clumping (endoplasmic reticulum/Golgi-associated) of the probes with an ensuing spread to the cytoplasm and periphery, accompanied by a better organization and more rapid response to biochemical stimuli, was seen on the complex matrix. CONCLUSIONS: A complex matrix overcomes cell polarity at a faster rate than myocytes cultured on a simple matrix, although both culture matrices were able to support cell growth and differentiation, and single-layer cultures are a good method by which structural and biochemical data can be obtained. The use of a native, complex matrix is preferable to employing a simple, single protein, although temporal aspects of cell growth must be considered regarding the particular aspect of the cell structure development/biochemical pathways that the researcher intends focusing on.
Sepsis induced by exposure to lipopolysaccharide (LPS) can be life-threatening and lead to multiple-organ dysfunction. Sepsis-associated cardiac dysfunction is a primary cause of mortality. The response of isolated cardiac myocytes to LPS exposure is poorly understood. Cultured neonatal rat ventricular cardiomyocytes were used to evaluate the response to LPS exposure. Other authors have reported that LPS exposure at doses sufficient to induce tumor necrosis factor alpha (TNF-alpha) production and apoptosis in adult cardiomyocytes do not induce apoptosis in neonatal cardiomyocytes. We therefore hypothesized that neonatal cardiomyocytes have innate protective mechanisms that protect from septic damage. Cultured neonatal rat ventricular cardiomyocytes were stimulated by exposure to LPS for varying lengths of time. NFkappaB signaling pathways, TNF-alpha production, and Akt activation were monitored. We also assessed the induction of apoptosis in these cells by monitoring caspase-3 activity. LPS rapidly stimulates nuclear translocation of NFkappaB and Akt activation. TNF-alpha production is also stimulated. However, high doses of LPS are unable to induce apoptosis in these cells, and protection is not a function of Akt activation. LPS treatment also stimulated the levels of cyclooxygenase-2 and the production of downstream metabolites, specifically PGE2 and 15deoxyDelta12-14PGJ2 (15dPGJ2). Specific inhibition of cyclooxygenase-2 activity induced apoptosis in the presence of LPS, whereas direct exposure to 15dPGJ2 at pharmacological levels induced apoptosis. Neonatal rat ventricular cardiomyocytes have innate protective mechanisms that prevent apoptotic cell death after LPS exposure. Metabolic products of arachidonic acid metabolized by the cyclooxygenase pathway can be potentially apoptotic or antiapoptotic. The balance of these products within these cells may define the cellular response to LPS exposure.
We describe a case of primary lymphoma of the thoracic aorta that presented as an aneurysm of the descending thoracic aorta. The aortic tumor was successfully resected with 2-year disease-free survival.
BACKGROUND: The heart undergoes repair and initiates protective mechanisms via ventricular unloading. We examined the presence of 2 markers in pre-unloaded and post-unloaded human cardiac tissue that are important indicators of cardiac failure, tumor necrosis factor-alpha and inducible nitric oxide synthase. We also measured 2 nuclear transcription factors, NFkappaB50 and NFkappaB65, comparing quantities and localizations to determine if mechanical unloading reduced their presence, as these markers are also thought to be indicators of impending heart failure. Amounts and localizations in patients that had been diagnosed with either ischemic or non-ischemic cardiomyopathy were compared after mechanical unloading with a left ventricular assist device. To establish that unloading had been achieved, levels of atrial natriuretic protein were determined. METHODS: Core biopsies were harvested at assist device implantation and removal. Fluorescence deconvolution microscopy image reconstructions of fluorescence probes were correlated with data obtained by western Blot and electrobility shift assays. RESULTS: Statistically significant differences in localization and amounts of tumor necrosis factor and nitric oxide synthase were seen between pre- and post-assist device samples. Amounts of tumor necrosis factor and nitric oxide synthase in ischemic tissue were increased at the time of assist device removal, but decreased in dilated or idiomyopathic samples. Ventricular unloading resulted in reduced levels of natriuretic protein, with the greatest reduction being seen in ischemic tissue. Both NFkappaB50 and NFkappaB65 increased in ischemic tissue, but only NFkappaB50 in non-ischemic samples. CONCLUSIONS: Changes in localization of the factors and altered levels of cytokine and nitric oxide synthase indicate that the heart switches to a "protective and repair" mode, and mechanical unloading allows this transition to occur. Observed changes were dependent on the etiology of the disease.
Cardiac alpha one adrenoreceptors (alpha(1)AR) are known to mediate positive inotropism in human ventricular myocardium. In the early stages of heart failure, ventricular contractility is maintained by adrenergic stimulation, rennin-angiotensin activation, and other neurohormonal and cytokine system responses. As the disease progresses, however, these compensatory mechanisms cease to provide benefit; ventricular dilation and fibrosis occur and cardiac function deteriorates. When ventricular contractility becomes severely depressed and is no longer responsive to inotropic support, insertion of a left ventricular assist device (LVAD) may allow the left ventricle to rest, remodel, and recover some contractile function. Our previous work has demonstrated that the myocardium has the capacity to repair itself during a period of unloading, after which some patients are able to resume a normal lifestyle and no longer need a cardiac transplant.
Acute infection with human herpesvirus-6 induces physiological cell proliferation in persons without major immune deficiency. It thus can serve as a parameter to validate a mathematical model designed to simulate cell proliferation under physiological and pathological conditions. Such a mathematical model is presented to simulate various cell changes of the T-cell immune system during the course of HHV-6 infection. Model development follows several steps, beginning with a basic model containing physiological T-cell pools to the introduction of infectious stimuli in the final model. A search algorithm designed to optimize the system parameters, as well as initial variables of the model, is presented. The results of simulation runs for acute HHV-6 infection of the final computational model correspond well to the data, as documented in human patients; they suggest that the computational model presented for the simulation of T-cell levels in a given viral infection may well serve as a tool for similar studies of other viral infections, including those that lead to cellular aplasia or neoplasia.
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Syndecan-4 (syn-4), a transmembrane heparan sulfate-containing proteoglycan, is unique among the four members of the syndecan family in its specific cellular localization to complex cytoskeletal adhesion sites, i.e., focal adhesions. During early phenotypic redifferentiation of neonatal cardiomyocytes in culture, immunolocalization reveals syn-4 to be heavily concentrated in the perinuclear endoplasmic reticulum-Golgi region, with little found at the peripheral regions. Subsequently, syn-4 becomes localized to a cytoskeletal adhesion complex unique to striated muscle, the costamere. Soon after redifferentiation of myofibrils in cultured neonatal cardiomyocytes, syn-4 is present only in costameres, not in focal adhesions. In cultured adult cardiomyocytes, it is present in both costameres and focal adhesions-the latter in two distinct regions of the spread cardiomyocytes, reflecting localization with two types of actin-containing filaments. The fact that syn-4 is observed early in the costameric regions, as opposed to later in the focal adhesions, suggests that it may play an initial role in early adhesion/signal transduction mechanisms in close proximity to the contractile apparatus, as well as in transmission of contractile force to the collagenous extracellular matrix (ECM) which surrounds the cardiac myofibers in situ. With respect to possible regulatory mechanisms of syn-4, we localized syn-4 with both the epsilon isoform of protein kinase C and the tyrosine kinase pp60(csrc) in costameric regions. These findings suggest that syn-4 may not only play a role in cellular adhesion and contractile force transmission, it may also, through ser, thr, and tyr phosphorylation, be part of an interactive signal transduction mechanism in myocardial functioning via these adhesive cytoskeletal complexes.
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OBJECTIVE: chronic aortic dissection has long been considered a risk factor for neurologic deficit following thoracoabdominal aortic aneurysm (TAA) surgery. We reviewed our experience with regard to aneurysm extent and the use of adjunct, (distal aortic perfusion/cerebrospinal fluid drainage), and examined the impact of these factors on neurologic deficit among chronic dissection and non-dissection cases. METHODS: between February 1991 and March 2001, we repaired 800 aneurysms of the descending thoracic and thoracoabdominal aorta. Seven hundred and twenty-nine cases were elective; 196 chronic dissection, 533 non-dissection. 182/729 (24.9%) were TAA extent II. Among these, 61/182 (33%) involved chronic dissection. Adjunct was used in 507/729 (69.6%). We conducted detailed multivariate analyses to isolate the impact of chronic aortic dissection on neurologic morbidity, with other important risk factors taken into account. RESULTS: overall, 32/729 (4.4%) patients had neurologic deficit upon awakening; 7/196 (3.6%) in chronic dissections, and 25/533 (4.7%) in non-dissections. Adjunct had a major effect, reducing neurologic deficit in TAA extent II from 10/36 (27.8%) to 10/146 (6.9%) (p=0.001). However, in univariate and multivariate analysis, chronic dissection did not increase the risk of neurologic deficit, regardless of extent or mode of treatment. CONCLUSION: in contrast to previous reports, we determined that chronic aortic dissection is not a risk factor in TAA patients.
OBJECTIVE: We sought to determine whether pretreatment with a sodium/hydrogen-exchange inhibitor (EMD 96 785) improves myocardial performance and reduces myocardial edema after cardioplegic arrest and cardiopulmonary bypass. METHODS: Anesthetized dogs (n = 13) were instrumented with vascular catheters, myocardial ultrasonic crystals, and left ventricular micromanometers to measure preload recruitable stroke work, maximum rate of pressure rise (positive and negative), and left ventricular end-diastolic volume and pressure. Cardiac output was measured by means of thermodilution. Myocardial tissue water content was determined from sequential biopsy. After baseline measurements, hypothermic (28 degrees C) cardiopulmonary bypass was initiated. Cardioplegic arrest (4 degrees C Bretschneider crystalloid cardioplegic solution) was maintained for 2 hours, followed by reperfusion-rewarming and separation from cardiopulmonary bypass. Preload recruitable stroke work and myocardial tissue water content were measured at 30, 60, and 120 minutes after bypass. EMD 96 785 (3 mg/kg) was given 15 minutes before bypass, and 2 micromol was given in the cardioplegic solution. Control animals received the same volume of saline vehicle. Arterial-coronary sinus lactate difference was similar in both animals receiving EMD 96 785 and control animals, suggesting equivalent myocardial ischemia in each group. RESULTS: Myocardial tissue water content increased from baseline in both animals receiving EMD 96 785 and control animals with cardiopulmonary bypass and cardioplegic arrest but was statistically lower in animals receiving EMD 96 785 compared with control animals (range, 1.0%-1.5% lower in animals receiving EMD 96 785). Preload recruitable stroke work decreased from baseline (97 +/- 2 mm Hg) at 30 (59 +/- 6 mm Hg) and 60 (72 +/- 9 mm Hg) minutes after cardiopulmonary bypass and cardioplegic arrest in control animals; preload recruitable stroke work did not decrease from baseline (98 +/- 2 mm Hg) in animals receiving EMD 96 785 and was statistically greater at 30 (88 +/- 5 mm Hg) and 60 (99 +/- 4 mm Hg) minutes after bypass and arrest compared with control animals. CONCLUSIONS: Sodium/hydrogen-exchanger inhibition decreases myocardial edema immediately after cardiopulmonary bypass and cardioplegic arrest and improves preload recruitable stroke work. Sodium/hydrogen-exchange inhibition during cardiac procedures with cardiopulmonary bypass and cardioplegic arrest may be a useful adjunct to improve myocardial performance in the immediate postbypass or arrest period.
The saturated fatty acid palmitate induces apoptosis in neonatal rat cardiomyocytes. This apoptosis is associated with early mitochondrial release of cytochrome c and a subsequent loss of mitochondrial membrane potential. Recent reports implicate a role for reactive oxygen species (ROS) in palmitate-induced apoptosis. We studied the role of ROS in palmitate-induced apoptosis in the neonatal rat cardiomyocyte and report no evidence of ROS involvement. ROS production, nitric oxide production, and nuclear factor-kappaB activation were not increased above those observed using the nonapoptotic fatty acid oleate. Indeed, the production of ROS was significantly higher in cells treated with oleate. Furthermore, the presence of antioxidants and ROS scavengers did not attenuate the induction of apoptosis by palmitate. Variations in the fatty acid-to-albumin ratio from 2:1 to 7:1 had no effect on the absence of ROS production or on the extent of apoptosis. No evidence was found for an increase in oxidative protein modification in palmitate-treated cells. Our results lead us to conclude that oxidative stress does not play a role in palmitate-induced apoptosis.
Myocardial ischemic injury results from severe impairment of coronary blood supply and produces a spectrum of clinical syndromes. As a result of intensive investigation over decades, a detailed understanding is now available of the complexity of the response of the myocardium to an ischemic insult. Myocardial ischemia results in a characteristic pattern of metabolic and ultrastructural changes that lead to irreversible injury. Recent studies have explored the relationship of myocardial ischemic injury to the major modes of cell death, namely, oncosis and apoptosis. The evidence indicates that apoptotic and oncotic mechanisms can proceed together in ischemic myocytes with oncotic mechanisms and morphology dominating the end stage of irreversible injury. Myocardial infarcts evolve as a wavefront of necrosis, extending from subendocardium to subepicardium over a 3- to 4-hour period. A number of processes can profoundly influence the evolution of myocardial ischemic injury. Timely reperfusion produces major effects on ischemic myocardium, including a component of reperfusion injury and a greater amount of salvage of myocardium. Preconditioning by several short bouts of coronary occlusion and reperfusion can temporarily salvage significant amounts of myocardium and extend the window of myocardial viability. Ongoing research into the mechanisms involved in reperfusion and preconditioning is yielding new insights into basic myocardial pathobiology.
Cardiovascular pathology is a subspecialty of anatomic pathology that requires both clinical education and expertise in contemporary physiopathology. The Society for Cardiovascular Pathology sponsored a special workshop within the frame of the USCAP Annual Meeting, held in Vancouver, March 6-12, 2004, to address the present and future role of cardiovascular pathology in research, clinical care, and education. Clearly, the recruitment and training of young pathologists are crucial to this aim. The forum tried to answer a series of questions. First, is there room for cardiovascular pathologists and clinicopathologic correlations in the era of extraordinary advances of in vivo human body imaging? What is the evolving role of the autopsy? How can the cardiovascular pathologist simultaneously be an autopsy prosector, a surgical pathologist, a molecular pathologist, and an experimental pathologist? Is there a specific domain content for training in cardiovascular pathology and does it meet the constellation of market needs and demands? What are the experiences in Europe, North America and elsewhere? What is the influence of cardiovascular pathology in departments of pathology? Is the subdiscipline still a Cinderella in the anatomic theatre or a Princess with a double helix coat of arms? The Society for Cardiovascular Pathology is strongly committed to optimizing the academic and professional profile of the future generation of cardiovascular pathologists. This article reports the outcome of the forum and directions that may lead to a vibrant future for well-trained cardiovascular pathologists.
BACKGROUND: The use of left ventricular (LV) assist devices (LVADs) can improve performance and recovery of failing human hearts. AIM: Following our alpha-adrenergic receptor work, we hypothesized that mechanical unloading in patients with low output syndrome and LV failure would yield similar results with beta-adrenergic receptors ((beta)AR), that being increased numbers and intra-myocytic relocalization. METHODS: (beta)AR density and localization were investigated by fluorescence deconvolution microscopy and compared at LVAD insertion and removal in 13 heart failure patients, the patients therefore acting as their own control. (beta)AR densities and distribution were determined in snap frozen sections of human core biopsy left ventricular apical tissue. Samples were probed with tagged CGP 12177 for visualization of (beta)AR and challenged with cold agonists and antagonists. (beta)AR density was measured by two independent methods. Localization of receptors was examined in reconstructed, deconvoluted, stacked section images. RESULTS: There was an increase in (beta)AR density following ventricular unloading in most of the patients, and also significant normalization in the location of the receptors in the myocardium comparing pre- and post-LVAD tissue. CONCLUSIONS: These findings suggest that supporting an ailing heart via unloading initiates mechanisms and pathways responsible for myocardial recovery and repair. With appropriate pharmacological support, patients with LVAD might recover to the point where they no longer depend on eventual organ transplantation, and (beta)AR number, type, and distribution in pre-LVAD myocardial tissue, could predict outcome with regard to recovery, repair, and improvement in cardiac function.
A literature search for HTLV-1-induced adult T-cell leukemia (ATL) at the National Library of Medicine resulted in 1003 publications which were evaluated with regard to HTLV-1 virus load, apoptosis and peripheral blood leukocyte changes during the latent period and leukemia development following virus infection. The data are presented in a comparable way to previous publications of infections with HHV-6 and HIV (which target the same CD4+ cell for infection) to be used for computer validation studies. After initial infection, HTLV-1 remains clinically latent for many years at low provirus copy numbers in CD4 cells. Once immune surveillance deteriorates and viral replication progresses, provirus copy numbers increase rapidly. Unlike other virus infections, apoptotic death of virus-infected "atypical" lymphocytes decreases with increasing viral load, thus favoring continued proliferation of these cells and further virus replication at the same time. Changes in the peripheral blood are characterized by coincident rises in oligoclonal lymphocyte populations including HTLV-1-positive CD4+ T-lymphocytes and their precursors with a progressive shift to immature cells as disease progresses. The pathogenesis of HTLV-1-induced adult T-cell leukemia is an example of dysregulative leukemogenesis ideal for validation of respective computer simulation models.