Rationale The phenotypes of vascular smooth-muscle cells (vSMCs) comprise a continuum bounded by predominantly contractile and synthetic cells. Some evidence suggests that contractile vSMCs can assume a more synthetic phenotype in response to ischemic injury, but the mechanisms that activate this phenotypic switch are poorly understood. Objective To determine whether lactate, which increases in response to regional ischemia, may promote the synthetic phenotype in vSMCs. Methods and Results Experiments were performed with vSMCs that had been differentiated from human induced pluripotent stem cells and then cultured in glucose-free, lactate-enriched (L+) medium or in standard (L−) medium. Compared to the L− medium, the L+ medium was associated with significant increases in synthetic vSMC marker expression, proliferation, and migration, and with significant declines in contractile and apoptotic activity. Furthermore, these changes were accompanied by increases in the expression of monocarboxylic acid transporters (MCT) and were generally attenuated both by the blockade of MCT activity and by transfection with iRNA for N-myc downstream regulated gene (NDRG). Proteomics, biomarker, and pathway analyses suggested that the L+ medium tended to upregulate the expression of synthetic vSMC markers, the production of extracellular proteins that participate in tissue construction or repair, and the activity of pathways that regulate cell proliferation and migration. Observations in hypoxia-cultured vSMCs were similar to those in L+ cultured vSMCs, and assessments in a swine myocardial infarction model suggested that measurements of lactate levels, lactate dehydrogenase levels, vSMC proliferation, and MCT and NDRG expression were greater in the ischemic zone than in nonischemic tissues. Conclusions These results demonstrate for the first time that vSMCs assume a more synthetic phenotype in a microenvironment that is rich in lactate. Thus, mechanisms that link glucose metabolism to vSMC phenotypic switching could play a role in the pathogenesis and treatment of cardiovascular disease.

Conventional protocols for differentiating human induced-pluripotent stem cells (hiPSCs) into smooth-muscle cells (SMCs) can be inefficient and generally fail to yield cells with a specific SMC phenotype (i.e., contractile or synthetic SMCs). Here, we present two novel hiPSC-SMC differentiation protocols that yield SMCs with predominantly contractile or synthetic phenotypes. Flow cytometry analyses of smooth-muscle actin (SMA) expression indicated that ~45% of the cells obtained with each protocol assumed an SMC phenotype, and that the populations could be purified to ~95% via metabolic selection. Assessments of cellular mRNA and/or protein levels indicated that SMA, myosin heavy chain II, collagen 1, calponin, transgelin, connexin 43, and vimentin expression in the SMCs obtained via the Contractile SMC protocol and in SMCs differentiated via a traditional protocol were similar, while SMCs produced via the Sythetic SMC protocol expressed less calponin, more collagen 1, and more connexin 43. Differences were also observed in functional assessments of the two SMC populations: the two-dimensional surface area of Contractile SMCs declined more extensively (to 12% versus 44% of original size) in response to carbachol treatment, while quantification of cell migration and proliferation were greater in Synthetic SMCs. Collectively, these data demonstrate that our novel differentiation protocols can efficiently generate SMCs from hiPSCs.

In CaWO, intrinsic hole centers are created by X-irradiation and localized a t one oxygen of the WO, tetrahedron a t temperatures below 150 K. More information about this trapping mechanism can be obtained by EPR measurements with applied uniaxial pressure and by optical absorption measurements. The results point to a Jahn-Teller instability as the main part of this mechanism leading to a trigonal distortion of the tetrahedron.Durch Rontgenbestrahlung werden in CaWO, intrinsische Lochzentren gebildet, die bei Temperaturen unterhalb 150 K an einem Sauerstoff eines W0,-Tetraeders lokalisiert sind. Durch ESR-Messungen unter uniaxialem Druck und optische Absorptionsmessungen konnen nLhere Aufschlusse uber diesen StabilisierungsprozeB gewonnen werden. Die Ergebnisse deuten auf eine Jahn-TellerInstabilitat als Hauptursache dieses Mechanismus hin, die zu einer trigonalen Verzerrung des Tetraeders fuhrt.

The purpose of this study was to investigate the effect of spinal instrumentation on the intradiscal pressure (IDP) within the fixed motion segment. In vitro biomechanical testing was performed in six single functional spinal units of fresh calf lumbar spines using a pressure needle transducer. Various loads were applied by a materials testing system device. In addition to intact spine (control), anterior spinal instrumentation (ASI) and pedicle screw fixation (PS) constructs, as well as destabilized spine were tested. Relative to the control, the destabilized spine tended to have an increased IDP; by 15% in axial compression and by 9-36% in flexion-extension. Compared to the control, PS decreased the IDP by 23% in axial loading and 51% in extension loading and increased it by 60% in flexion for each loading. ASI decreased the IDP by 32% in flexion and 1% in extension. Lateral bending produced symmetrical changes of IDP in the control and destabilized spine, but no change in the PS construct. The IDP of the ASI construct was decreased by 77% in ipsilateral bending and increased by 22% in contralateral bending. These results demonstrated that eccentric loading from the spinal instruments increased IDP and significant disc pressure may still exist despite an increase in motion segment stiffness after lumbar stabilization.

In vitro biomechanical testing was performed in single-functional spinal units of fresh calf lumbar spines, using pressure needle transducers to investigate the effect of posterolateral fusion (PLF) and pedicle screw constructs (PS) on intradiscal pressure (IDP), in order to elucidate the mechanical factors concerned with residual low back pain after PLF. IDP of 6 calf lumbar spines consisting of L4 and L5 vertebrae and an intervening disc was measured under axial compression, flexion-extension and lateral bending in the intact spine, PS, PLF and the destabilized spine. Relative to the intact spines, the destabilized spines showed increased IDP in all of lordings and moments. IDP under PS and PLF were significantly decreased in axial compression, extension and lateral bending loads (p<0.05). In flexion, IDP under PS and PLF increased linearly proportional to the magnitude of flexion moment and reached as high as IDP of the intact spines. These results demonstrated that despite an increase in the stiffness of motion segments after PLF and PS, significant high disc pressure is still generated in flexion. Flexibility of PS and PLF may cause increased axial load sharing of the disc in flexion and increased IDP. This high IDP may explain patients' persisting pain following PS and PLF.

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In a bobsled race, the difference between a winning and losing time can be less than thousandths of a second. These fractions of seconds are typically gained or lost at the start. The athletes must be keenly aware of their time and ability to accelerate the sled. Since bobsledders will only complete three or four runs a day during training, optimization of their mechanics and timing must all be done in a few training sessions. Also, the bobsled tracks are only available for a portion of the year and there is great demand for the facility, when seasonal temperatures allow the ice to be maintained. Unlike other sports they cannot rely upon “muscle memory,” where optimization is achieved through repetition. The “Bobsled Start Simulator” was designed to give bobsledders a tool to optimize the start variables without having to train on a track. The result was a high-tech treadmill with a computerized velocity control, a bobsled handle attached to a six-degree of freedom load cell and an adjustable attachment mechanism for mounting to the load cell and bobsled handle to the treadmill. The device was tested and proved successful in improving not only pushing force but also timing for six U.S. Olympic Team athletes. The work presented in this paper was completed in 2001 for the 2002 Olympics. At the time, the U.S. Olympic Bobsled Committee asked us to not make the information public until after the 2006 Olympics.