Bauer E. Sumpio

Cells in focus: endothelial cell

The endothelial cell is thought to arise from the splanchnopleuric mesoderm. Endothelial cells form the inner lining of a blood vessel and provides an anticoagulant barrier between the vessel wall and blood. In addition to its role as a selective permeability barrier, the endothelial cell is a unique multifunctional cell with critical basal and inducible metabolic and synthetic functions. The endothelial cell reacts with physical and chemical stimuli within the circulation and regulates hemostasis, vasomotor tone, and immune and inflammatory responses. In addition, the endothelial cell is pivotal in angiogenesis and vasculogenesis. Endothelial cell injury, activation or dysfunction is a hallmark of many pathologic states including atherosclerosis, loss of semi-permeable membrane function, and thrombosis. Cell facts: (1) Endothelium consists of approximately (1-6) x 10(13) endothelial cells forming an almost 1 kg organ. (2) They uniquely contain Weibel-Palade bodies, 0.1 microm wide, 3 microm long membrane-bound structures that represent the storage organelle for von Willebrand factor (vWF). (3) The endothelial cell is not only a permeability barrier but also a multifunctional paracrine and endocrine organ. It is involved in the immune response, coagulation, growth regulation, production of extracellular matrix components, and is a modulator of blood flow and blood vessel tone.

Cyclic strain upregulates nitric oxide synthase in cultured bovine aortic endothelial cells.

In vivo, endothelial cells (EC) are subjected to hemodynamic forces which may influence the production of nitric oxide. This study was designed to examine the effect of cyclic strain on the expression of endothelial nitric oxide synthase (eNOS) in cultured bovine aortic EC. EC were grown on flexible membranes which were subjected to deformation at 60 cycles/min with -5 or -20 kPa of vacuum. This results in an average strain of 6 and 10%, respectively, which is transmitted to the attached cells. Northern blot analysis of total cytosolic RNA demonstrated an increase in eNOS gene expression with both strain regimens but the increase with 10% average strain was greater than that at 6%. Nuclear runoff transcription assays confirmed the induction of eNOS transcripts. Western blot analysis showed an increase in eNOS level after 24 h of cyclic 10% average strain compared with controls or 6% average strain. Immunohistochemical staining of EC for eNOS was increased in the high strain periphery (7-24% strain) of membranes deformed with -20 kPa vacuum. These results demonstrate that cyclic strain upregulates the expression of eNOS transcripts and protein levels in bovine aortic EC thus emphasizing the importance of hemodynamic forces in the regulation of eNOS in vivo.

Morphological response of human endothelial cells subjected to cyclic strain in vitro.

Endothelial cells (EC) are subjected to hemodynamic forces in vivo. However, most in vitro studies of EC biology have been performed utilizing stationary culture conditions. To study the morphology and cytoskeletal features of EC under dynamic culture conditions, we utilize a system capable of exerting repetitive strain on cells in culture. Human saphenous vein EC were plated to a subconfluent density in 25-mm wells with a thin flexible bottom and a rat collagen, Type I surface. A -20 kPascals vacuum applied to the bottoms led to a maximum deformation of 24%. EC were exposed to 0.5 sec deformation alternating with 0.5 sec relaxation (60 cycles/min) for 24 hr. EC were fixed with formalin at different time intervals and stained with crystal violet. Actin filaments were stained with rhodamine phalloidin, an F-actin marker, while beta-tubulin and vimentin were visualized by immunofluorescent antibody techniques. Within 15 min after initiation of cyclic strain, actin stress fibers were aligned perpendicular to the force vector. By 12 hr of cyclic strain EC were elongated and oriented in the same direction as the actin filaments. EC elongation and alignment were inhibited by cytochalasin B. Even up to 24 hr of cyclic strain, beta-tubulin and vimentin distributions were unaltered. We propose that cyclic strain of EC in vitro influences cell alignment and elongation by a mechanism dependent on the actin filament system.

Distinct roles for the small GTPases Cdc42 and Rho in endothelial responses to shear stress

Shear stress, the tangential component of hemodynamic forces, plays an important role in endothelial remodeling. In this study, we investigated the role of Rho family GTPases Cdc42 and Rho in shear stress-induced signal transduction and cytoskeleton reorganization. Our results showed that shear stress induced the translocation of Cdc42 and Rho from cytosol to membrane. Although both Cdc42 and Rho were involved in the shear stress-induced transcription factor AP-1 acting on the 12-O-tetradecanoyl-13-phorbol-acetate-responsive element (TRE), only Cdc42 was sufficient to activate AP-1/TRE. Dominant-negative mutants of Cdc42 and Rho, as well as recombinant C3 exoenzyme, attenuated the shear stress activation of c-Jun NH2-terminal kinases (JNKs), suggesting that Cdc42 and Rho regulate the shear stress induction of AP-1/TRE activity through JNKs. Shear stress-induced cell alignment and stress fiber formation were inhibited by the dominant-negative mutants of Rho and p160ROCK, but not by the dominant-negative mutant of Cdc42, indicating that the Rho-p160ROCK pathway regulates the cytoskeletal reorganization in response to shear stress.

Response of porcine aortic smooth muscle cells to cyclic tensional deformation in culture

The vascular wall is continuously subjected to pulsatile hydrostatic pressures. However, most studies of smooth muscle cells (SMC) are done under static tissue culture conditions. We have utilized a flexible-bottom culture plate and applied cyclic tensional deformation to cultured SMC. Recent studies have shown that endothelial cells (EC) proliferate but remain randomly oriented when subjected to a force regimen of 3 cycle/min of up to 24% elongation. The current experiments were performed to study the effects of a similar force regimen on SMC. Porcine SMC were seeded at 200,000 cells/35-mm2 well and permitted to adhere for 24 hr. After 24 hr, the plates were placed on a vacuum-operated stress-providing unit that exerted a 24% elongation on the culture plate substratum at maximum downward deflection of the plate bottom. The stretched cells (n = 6 wells/day) were subjected to cycles of 10 sec of 24% elongation and 10 sec of relaxation for 7 days. The control cells (n = 6 wells/day) were subjected to similar incubations as the control group but without cyclic deformation. Media were changed every 24 hr. [3H]Thymidine (THY), a precursor for DNA synthesis, was added (2 microCi/well) to plates 24 hr prior to harvesting. On Days 0, 1, 3, 5, and 7 cells were counted and analyzed for THY incorporation. While previous results indicate that pulsatile stretching stimulates EC, the present study indicates that a similar regimen of stress inhibits SMC proliferation. THY incorporation into SMC paralleled the observed changes in cell count. Morphologically, SMC aligned in an annular pattern in response to applied strain, whereas EC maintained a random orientation.(ABSTRACT TRUNCATED AT 250 WORDS)

The Semmes Weinstein monofilament examination as a screening tool for diabetic peripheral neuropathy

OBJECTIVE The purpose of this systematic review is to evaluate current evidence in the literature on the efficacy of Semmes Weinstein monofilament examination (SWME) in diagnosing diabetic peripheral neuropathy (DPN). METHODS The PubMed database was searched through August 2008 for articles pertaining to DPN and SWME with no language or publication date restrictions. Studies with original data comparing the diagnostic value of SWME with that of one or more other modalities for DPN in patients with diabetes mellitus were analyzed. Data were extracted by two independent investigators. Diagnostic values were calculated after classifying data by reference test, SWME methodology, and diagnostic threshold. RESULTS Of the 764 studies identified, 30 articles were selected, involving 8365 patients. There was great variation in both the reference test and the methodology of SWME. However, current literature suggests that nerve conduction study (NCS) is the gold standard for diagnosing DPN. Four studies were identified which directly compared SWME with NCS and encompassed 1065 patients with, and 52 patients without diabetes mellitus. SWME had a sensitivity ranging from 57% (95% confidence interval [CI], 44% to 68%) to 93% (95% CI, 77% to 99%), specificity ranging from 75% (95% CI, 64% to 84%) to 100% (95% CI, 63% to 100%), positive predictive value (PPV) ranging from 84% (95% CI, 74% to 90%) to 100% (95% CI, 87% to 100%), and negative predictive value (NPV) ranging from 36% (95% CI, 29% to 43%) to 94% (95% CI, 91% to 96%). CONCLUSIONS There is great variation in the current literature regarding the diagnostic value of SWME as a result of different methodologies. To maximize the diagnostic value of SWME, a three site test involving the plantar aspects of the great toe, the third metatarsal, and the fifth metatarsals should be used. Screening is vital in identifying DPN early, enabling earlier intervention and management to reduce the risk of ulceration and lower extremity amputation.

The mechanisms of action of vacuum assisted closure: More to learn

Division of Plastic and Reconstructive Surgery, Brigham and Women’s Hospital , Boston, MA; Division of Plastic and Reconstructive Surgery, University of Pittsburg School of Medicine , Pittsburg, PA; Department of Surgery, Yale University School of Medicine , New Haven, CT; Department of Surgery, University of Chicago Hospitals , Chicago, IL; Limb Center, Georgetown University Medical Center, Washington, DC; Department of Surgery, Stanford University Medical Center, Stanford, CA; Division of Plastic Surgery, Department of Surgery, Penn State University Milton S. Hershey Medical Center, Hershey, PA

Meta-analysis of open versus endovascular repair for ruptured descending thoracic aortic aneurysm

INTRODUCTION Ruptured descending thoracic aortic aneurysm (rDTAA) is associated with high mortality rates. Data supporting endovascular thoracic aortic aneurysm repair (TEVAR) to reduce mortality compared with open repair are limited to small series. We investigated published reports for contemporary outcomes of open and endovascular repair of rDTAA. METHODS We systematically reviewed all studies describing the outcomes of rDTAA treated with open repair or TEVAR since 1995 using MEDLINE, Cochrane Library CENTRAL, and Excerpta Medica Database (EMBASE) databases. Case reports or studies published before 1995 were excluded. All articles were critically appraised for relevance, validity, and availability of data regarding treatment outcomes. All data were systematically pooled, and meta-analyses were performed to investigate 30-day mortality, myocardial infarction, stroke, and paraplegia rates after both types of repair. RESULTS Original data of 224 patients (70% male) with rDTAA were identified: 143 (64%) were treated with TEVAR and 81 (36%) with open repair. Mean age was 70 +/- 5.6 years. The 30-day mortality was 19% for patients treated with TEVAR for rDTAA compared 33% for patients treated with open repair, which was significant (odds ratio [OR], 2.15, P = .016). The 30-day occurrence rates of myocardial infarction (11.1% vs 3.5%; OR, 3.70, P < .05), stroke (10.2% vs 4.1%; OR, 2.67; P = .117), and paraplegia (5.5% vs 3.1%; OR, 1.83; P = .405) were increased after open repair vs TEVAR, but this failed to reach statistical significance for stroke and paraplegia. Five additional patients in the TEVAR group died of aneurysm-related causes after 30 days, during a median follow-up of 17 +/- 10 months. Follow-up data after open repair were insufficient. The estimated aneurysm-related survival at 3 years after TEVAR was 70.6%. CONCLUSION Endovascular repair of rDTAA is associated with a significantly lower 30-day mortality rate compared with open surgical repair. TEVAR was associated with a considerable number of aneurysm-related deaths during follow-up.

Olive Oil, the Mediterranean Diet, and Cardiovascular Health

r T d m p 0 t he Mediterranean Diet nhabitants of Southern European and North African reions surrounding the Mediterranean Sea have a longer life xpectancy and lower risk of chronic diseases than in other egions of the world. It is believed that the diet and lifestyle f these Mediterranean populations have led to decreased ates of cancer, diabetes, and heart disease. The 1968 Seven ountries Study concluded that coronary heart disease was ot a major indicator of mortality in men who inhabited he Greek island of Crete. The occurrence of myocardial nfarction, fatal and nonfatal, was 26 in 10,000 Cretans, in ontrast to the Northern Finland cohort, where the rate as 1,074 in 10,000. Although the Mediterranean diet aries somewhat regionally, its nutritional model of whole rains, vegetables, fruits, red wine, and olive oil is believed o contribute to decreased rates of coronary heart disease. A ecent survey in the region of Girona, Spain, of 3,179 subects found that adherence to the traditional Mediterranean iet was inversely associated with body mass index and besity, major risk factors for heart disease. Health benefits f the Mediterranean diet have precipitated studies on the ffects of its various components, specifically extra virgin live oil (EVOO). Mediterranean countries have maximized their use of live oil, becoming the largest consumers, producers, and xporters of both olives and olive oil. Together they manfacture approximately 90% of the total olive oil produced. ecause of olive oil’s role as the primary source of fat inake, the Mediterranean diet is high in monounsaturated atty acids (MUFA), specifically oleic acid, and low in satrated fatty acids (SFA). Studies affirm that dietary cisUFA have a greater antiatherosclerotic effect than SFA nd are comparable with the effects of polyunsaturated atty acids (PUFA) on cardiovascular risk factors. Worldwide, the Japanese and Cretan populations have he lowest SFA intake, 3% to 8% and 8% of total fat onsumption, respectively. The Japanese and Cretan co-

The critical role of hemodynamics in the development of cerebral vascular disease

Atherosclerosis and intracranial saccular aneurysms predictably localize in areas with complex arterial geometries such as bifurcations and curvatures. These sites are characterized by unique hemodynamic conditions that possibly influence the risk for these disorders. One hemodynamic parameter in particular has emerged as a key regulator of vascular biology--wall shear stress (WSS). Variations in geometry can change the distribution and magnitude of WSS, thus influencing the risk for vascular disorders. Computer simulations conducted using patient-specific data have suggested that departures from normal levels of WSS lead to aneurysm formation and progression. In addition, multiple studies indicate that disturbed flow and low WSS predispose patients to extracranial atherosclerosis, and particularly to carotid artery disease. Conversely, in the case of intracranial atherosclerosis, more studies are needed to provide a firm link between hemodynamics and atherogenesis. The recognition of WSS as an important factor in cerebral vascular disease may help to identify individuals at risk and guide treatment options.