The role of interdisciplinary team approach in the management of the diabetic foot: a joint statement from the Society for Vascular Surgery and the American Podiatric Medical Association

The Society for Vascular Surgery (SVS) and the American Podiatric Medical Association (APMA) recognize the beneficial impact of a multidisciplinary team approach on the care of patients with critical limb ischemia, especially in the diabetic population. As a first step in identifying clinical issues and questions important to both memberships, and to work together to find solutions that will benefit the shared patient, the two organizations appointed a representative group to write a joint statement on the importance of multidisciplinary team approach to the care of the diabetic foot.

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.

The effects of freezing versus supercooling on vascular cells: implications for balloon cryoplasty

PURPOSE

To investigate the effects of supercooling, a phase whereby cells are below 0 degrees C but still in a liquid state, and freezing, the phase when cells become solid, of vascular cells in culture.

MATERIALS AND METHODS

Bovine aortic endothelial cells and smooth muscle cells were supercooled to -10 degrees C with or without freezing for 3, 30, or 60 seconds and then rewarmed to 37 degrees C for 24 hours. Viability was assessed by means of trypan blue exclusion, and apoptosis was assessed with the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay.

RESULTS

Viability of smooth muscle cells decreased 49% after freezing versus supercooling (P< .05). Endothelial cells maintained greater viability rates. A 19.5% smooth muscle cell apoptotic rate was observed after freezing, whereas smooth muscle cell supercooling yielded rates of only 11% (P< .05). A 4.17% endothelial cell apoptotic rate was observed after freezing, whereas supercooled endothelial cells yielded a 1.76% rate (P< .05).

CONCLUSIONS

Freezing results in decreased viability and increased apoptosis compared to supercooling in both cell lines. Smooth muscle cells appear more susceptible to freezing. The biologic effects of freezing on vascular cells may elucidate the mechanisms behind the enhanced patency after cryoplasty of atherosclerotic lesions.

Role of integrins and focal adhesion kinase in the orientation of dermal fibroblasts exposed to cyclic strain

Stretch is applied to skin under normal physiological conditions, for example pregnancy, or artificially using soft tissue expanders. Because cells are known to orient in response to the application of mechanical forces, the current studies were carried out to assess the effects of stretch on dermal fibroblast orientation and cell signalling. Dermal fibroblasts were seeded onto collagen-coated flexible membranes and grown to 70-80% confluence. Membranes were then deformed at 10 cycles per minute by the application of 135 mmHg subatmospheric pressure. This corresponded to strain levels of 0-24% from the centre to extremity of the flexible membrane. We show that a minimum of 15% cell stretch is required to significantly stimulate the fibroblast orientation response. focal adhesion kinase (FAK), p38 and Rho were activated in fibroblasts exposed to cyclic stretch and incubation of cells with anti-integrin beta1 before the application of stretch abrogated fibroblast orientation, as well as FAK, p38 and Rho activation. Fibroblast orientation in response to cyclic stretch is mediated at least in part by integrin beta1 through phosphorylation of FAK, p38 and activation of Rho.

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.

Effects of Cyclic Strain on Vascular Cells

Hemodynamic forces, including shear stress and cyclic strain, have been recognized as important modulators of vascular cell morphology and function. The mechanism by which vascular cells sense and transduce the extracellular mechanical signals into the cell nucleus has only recently begun to come to light. Integrins, ion channels, platelet-derived growth factor receptors, and G proteins have been recognized as mechanosensors, converting the mechanical stimuli into chemical signals. Activation of second messengers, including mitogen-activated protein kinases, protein kinase C, and Akt, follows, leading to an increase in the activity of transcription factors such as activator protein (AP)-1, AP-2, cAMP-responsive element (CRE), early growth response (Egr)-1, and nuclear factor (NF)-kappa B. Binding of these factors to the DNA leads to activation of numerous genes that regulate cell proliferation, apoptosis, differentiation, morphology, migration, and secretory function. Understanding of these responses has provided new insights in the pathogenesis and treatment of vascular diseases, such as atherosclerosis and intimal hyperplasia.

Polyphenols are medicine: Is it time to prescribe red wine for our patients?

Alcohol, specifically red wine, has been suggested to play a key role in the prevention of cardiovascular disease and other chronic pathologies, including cancer. Its regular and moderate consumption has been found in numerous epidemiological studies to correlate inversely with vascular disease and mortality, despite the presence of risk factors such as high consumption of saturated fats, elevated smoking and low physical activity. This phenomenon, known as the 'French Paradox', would be explained mainly by the high levels of polyphenols present in red wine, making it more advantageous than beer, spirits and even white wine. The habit of having one or two drinks of red wine every day with meals may translate to a longer, healthier and better quality of life.

Role of negative pressure wound therapy in treating peripheral vascular graft infections

Wound complications involving large subcutaneous vessels can cause significant challenges for surgeons. Negative pressure wound therapy (NPWT) has been increasingly used for treating complex wounds in vascular surgery, including groin infections, either as a bridge to surgical closure or as a primary wound treatment modality. Although a growing body of evidence exists for managing various problematic wounds, such as diabetic foot ulcers and open abdominal wounds, the role of NPWT in wounds involving large blood vessels or wounds complicating infected vascular grafts has not been well defined. A multidisciplinary advisory panel reviewed the literature relevant to wounds related to vascular surgical procedures and complications, focusing on large subcutaneous or infected vascular conduits. The results supported by the literature and the clinical practice of the consensus panel suggested that NPWT can be a useful adjunct to the management of vascular groin infections and dehiscences but must be used with caution.

Differential effects of shear stress and cyclic strain on Sp1 phosphorylation by protein kinase Czeta modulates membrane type 1-matrix metalloproteinase in endothelial cells

Membrane type 1-matrix metalloproteinase (MT1-MMP) plays a key role in extracellular matrix remodeling, endothelial cell (EC) migration, and angiogenesis. Whereas cyclic strain (CS) increases MT1-MMP expression, shear stress (SS) decreases MT1-MMP expression. The aim of this study was to determine if changes in levels of Sp1 phosphorylation induced by protein kinase Czeta (PKCzeta) in ECs exposed to SS but not CS are important for MT1-MMP expression. The results showed that SS increased Sp1 phosphorylation, which could be inhibited by pretreatment with PKCzeta inhibitors. In the presence of PKCzeta inhibitors, the SS-mediated decrease in MT1-MMP protein expression was also abolished. These data demonstrate that increased affinity of Sp1 for MT1-MMP's promoter site occurs as a consequence of PKCzeta-induced phosphorylation of Sp1 in response to SS, increasing Sp1 binding affinity for the promoter site, preventing Egr-1 binding, and consequently decreasing MT1-MMP expression.

Synergistic effect of cool/thaw cycles on vascular cells in an in vitro model of cryoplasty

PURPOSE

Cryoplasty combines mechanical dilation with supercooling of the vessel and has shown encouraging preliminary results in the management of atherosclerotic lesions. However, the mechanisms of action and the optimum inflation regimen are still not well established. This study investigates the effects of single and dual supercooling and rewarming cycles on the survival responses of smooth muscle cells (SMCs) and endothelial cells (ECs).

MATERIALS AND METHODS

Bovine aortic SMCs and ECs were cultured separately in six-well plates with medium supplemented with 10% fetal bovine serum. In the one-cycle treatment group, the cells were supercooled for 60 seconds to -10 degrees C and then rewarmed rapidly in a water bath at 37 degrees C for another 60 seconds. Two-cycle treatment was done by supercooling and rewarming the cells twice. The samples were then put into an incubator at 37 degrees C for 0, 6, 12, and 24 hours. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was used to measure apoptosis and phospho-Akt immunohistochemistry and immunoblot analysis were employed to assess activation of Akt.

RESULTS

A significant increase of apoptotic cells was observed in the two-cycle procedure versus the one-cycle procedure. In both groups, there were more apoptotic SMCs than ECs. Akt activation was higher in ECs by a factor of three compared with SMCs (P < .05).

CONCLUSIONS

The higher apoptotic rate and the absence of Akt activation of SMCs versus controls in both treatment groups may imply the potential of a lower restenosis rate, especially after two cycles of supercooling and rewarming. Further in vivo and clinical investigations are needed to confirm results of the in vitro testing.

Thrombospondin-1-induced migration is functionally dependent upon focal adhesion kinase

Vascular smooth muscle cell migration is important in vascular disease. Previously, we showed thrombospondin-1 activates focal adhesion kinase in these cells. We hypothesized that focal adhesion kinase is important for thrombspondin-1-induced vascular smooth muscle cell migration. Bovine aortic smooth muscle cells were transfected with FAK397, FAK-wild type, pcDNA, or beta-Gal plasmids. Migration was assessed with thrombospondin-1 or serum-free medium in quiescent transfected cells or quiescent cells pretreated with the focal adhesion kinase inhibitor, geldanamycin. Number of cells migrated per 5 fields (x400) were recorded. Antihemagglutinin immunoprecipitation and Western blot were used to examine thrombospondin-1-induced focal adhesion kinase phosphorylation in transfected cells. FAK397 transfection inhibited thrombospondin-1-induced focal adhesion kinase phosphorylation and migration (P < .05). Geldanamycin inhibited thrombospondin-1-induced smooth muscle cell migration (P < .05). In conclusion, vascular smooth muscle cells transfected with FAK397 inhibited thrombosponin-1-induced migration and tyrosine phosphorylation. Further, geldanamycin also inhibited migration. These results suggest focal adhesion kinase is involved in thrombospondin-1-induced vascular smooth muscle cell migration.

Effect of different frequencies of tensile strain on human dermal fibroblast proliferation and survival

The aim of this study is to compare the effect of a high-frequency repetitive (HF) stretch or an intermittent (I) stretch on the cell proliferation and survival of human dermal fibroblasts and to determine the activation of any relevant signal pathways. Cultured human dermal fibroblasts were exposed to either HF or I stretch. Cell number was measured by counting, while DNA synthesis was assessed by 5-bromo-2'-deoxyuridine (BrdU) staining and apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. To investigate the potential mechanisms of repetitive strain on the proliferation and survival of fibroblasts, the activation of relevant transduction pathways, such as p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK)1/2, AKT, and BAD, was assessed by Western blot. In addition, the effect of inhibition of these pathways on the fibroblast response was also studied. After either HF or I stretch for 7 days, fibroblast number was significantly decreased and there were less BrdU-positive cells. The numbers of apoptotic and/or necrotic fibroblasts were not affected. p38 MAPK and ERK1/2 were significantly activated after HF stretch, but AKT and BAD were significantly activated after I stretch. The inhibitors of p38 MAPK and MAPK/ERK kinase as well as dominant-negative AKT reduced cell number after both HF and I stretch but these pathways were not critical for the stretch-induced decrease in cell number.