Induced osteogenic differentiation of human smooth muscle cells as a model of vascular calcification.

Vascular calcification is a severe pathological event in the manifestation of atherosclerosis. Pathogenic triggers mediating osteogenic differentiation of arterial smooth muscle cells (SMC) in humans remain insufficiently understood and are to a large extent investigated in animal models or cells derived thereof. Here, we describe an in vitro model based on SMC derived from healthy and diseased humans that allows to comprehensively investigate vascular calcification mechanisms. Comparing the impact of the commonly used SMC culture media VascuLife, DMEM, and M199, cells were characterised by immunofluorescence, flow cytometry, qPCR, and regarding their contractility and proliferative capacity. Irrespective of the arterial origin, the clinical background and the expansion medium used, all cells expressed typical molecular SMC marker while contractility varied between donors. Interestingly, the ability to induce an osteogenic differentiation strongly depended on the culture medium, with only SMC cultured in DMEM depositing calcified matrix upon osteogenic stimulation, which correlated with increased alkaline phosphatase activity, increased inorganic phosphate level and upregulation of osteogenic gene markers. Our optimized model is suitable for donor-oriented as well as broader screening of potential pathogenic mediators triggering vascular calcification. Translational studies aiming to identify and to evaluate therapeutic targets in a personalized fashion would be feasible.

Diagnostic value of proton MR spectroscopy in peripheral arterial occlusive disease: a prospective evaluation.

OBJECTIVE: The objective of the present study was to determine the detectability of metabolic alterations in patients with peripheral arterial occlusive disease (PAOD) using proton MR spectroscopy (hydrogen-1 MR spectroscopy). SUBJECTS AND METHODS: Twenty-seven people were included in this study: 10 patients with PAOD and a pain-free walking distance of less than 200 m served as the patient group and 17 young healthy subjects served as a control group. Hydrogen-1 MR spectroscopy was performed on a 1.5-T scanner using an extremity coil and a point-resolved spectroscopy (PRESS) sequence (TR/TE, 1,500/30; 256 repetitions). For the patient group, a voxel was localized in the gastrocnemius muscle of the diseased leg. The data were processed using standard 1H MR spectroscopy tools. The identification of resonances detected on all MR spectra was made: intramyocellular lipids at 1.2 ppm, extramyocellular lipids at 1.6 ppm, lactate at 4.1 ppm, glucose with two main peaks at 3.4 and 3.8 ppm, choline at 3.2 ppm, and creatine at 3.0 and 3.9 ppm. To avoid operator bias, three spectral intensities were measured after correcting baseline and phase of MR spectra each time. The creatine signal was used as an internal reference; thus, all spectra were scaled relative to creatine. We compared the resultant intensity ratios between the two groups using the Mann-Whitney U test. RESULTS: The lactate-creatine quotient was higher in the patient group, with a ratio of 1.6, than in the control group, with a ratio of 0.6. The glutamate-creatine ratio was higher in the patient group than in the control group (1.3 vs 0.8, respectively). All other ratios were higher in the control group. The best ratio for differentiating between healthy subjects and patients with PAOD was the glucose-lactate ratio. The patient group had a glucose-lactate quotient of 5.4, whereas the control group had a glucose-lactate quotient of 21.5 (p = 0.001). CONCLUSION: Proton MR spectroscopy has the potential to allow identification of patients who have PAOD on the basis of altered muscle metabolism.

Lethal heparin-associated pulmonary embolism--case reports.

Thrombocytopenia is a known adverse reaction occurring in some patients receiving heparin. Two different types of heparin-induced thrombocytopenia have been described. Heparin-induced thrombocytopenia type I is a mild thrombocytopenia after 1 to 4 days of heparin therapy, attributed to a direct interaction between heparin and circulating platelets. No specific treatment is necessary. Heparin-induced thrombocytopenia type II is a severe thrombocytopenia mediated by an immunologic mechanism. Type II generally develops after 5 to 10 days of heparin therapy and can be associated with potentially devastating thromboembolic complications. The incidence of heparin-induced thrombocytopenia type II is below 3%. Thromboembolic events are always accompanied by a decrease in the platelet count, however, complications in the absence of absolute thrombocytopenia have been reported. Diagnosis of HIT type II is based on clinical features and laboratory studies for the heparin-dependent platelet antibody. Immediate cessation of heparin administration is essential. Several alternative anticoagulant therapies have been studied and have shown promising results when used for this purpose. Two patients undergoing coronary artery bypass surgery are presented in whom pulmonary embolism developed due to heparin-induced thrombocytopenia type II. In both cases, platelet counts were within the subnormal range at the time of the first thromboembolic complication. The clinical, therapeutic, and prognostic implications are discussed.

Anaerobic cellulitis as the result of Clostridium perfringens: a rare cause of vascular access graft infection.

Infection of prosthetic vascular access grafts is the second most common complication of vascular access and represents a challenge encountered by the vascular surgeon. Anaerobic graft infections are rare. We report on a case of a prosthetic vascular access graft infection with Clostridium perfringens. To our knowledge, only one other case with an infected arteriovenous shunt caused by C perfringens has been reported. The patient, a 67-year-old woman with end-stage renal failure as the result of polycystic renal disease, was seen with an infected pseudoaneurysm at the arterial puncture site of the loop graft on the left arm. There was associated purulence at the time of operation. Surgical management consisted of complete graft removal because of the presence of small tunnel abscesses. C perfringens was found in the resected pseudoaneurysm and graft material. Infected pseudoaneurysms most likely are attributable to repetitive punctures in one small area and to a break in sterile technique. A compromised vascular supply, not infrequent in patients for hemodialysis, may lower the oxidation reduction potential, which allows anaerobic bacteria, such as C perfringens, to cause infection.