VIPER-2: a prospective, randomized single-center comparison of 2 different closure devices with a hemostatic wound dressing for closure of femoral artery access sites.

PURPOSE: To report the outcome of a prospective randomized safety and performance trial of 2 access site closure devices versus a wound dressing. METHODS: Between October 2005 and July 2006, 852 consecutive patients (605 men; mean age 67 years) undergoing diagnostic or interventional catheterization procedures thru a 5- or 6-F femoral sheath were randomized to one of the 3 closure methods: a collagen plug device (Angio-Seal), a clip (StarClose), or a wound dressing (D-Stat Dry). The efficacy of the devices was assessed, as well as the complications occurring at the puncture site during the hospital stay. The primary endpoint of the study was the cumulative incidence of access site pseudoaneurysm, major access site bleeding requiring transfusion, access site vascular surgery, or death from all causes. RESULTS: There were no significant differences in baseline characteristics between the 3 treatment groups. The primary endpoint was reached in 20 (7.1%) of 281 patients treated with D-Stat Dry and in 11 (1.9%) of 571 patients treated with the mechanical closure devices (p<0.0001). There was no significant difference among the mechanical closure devices concerning the incidence of the primary endpoint (Angio-Seal 1.1% versus StarClose 2.8%; p = 0.13). CONCLUSION: The collagen plug device had the lowest rates of major and minor access site-related complications after removal of 5- or 6-F femoral sheaths. The difference between the mechanical closure devices concerning the incidence of the primary endpoint did not reach statistical significance. The wound dressing showed significantly higher major and minor complication rates.     

Secretory products from human adipocytes impair endothelial function via nuclear factor kappaB

Hyperplasia and hypertrophy of fat cells can be found in obesity, and increased adiposity is associated with endothelial dysfunction as an early event of atherosclerosis. However, it is unclear whether human adipocytes directly influence endothelial function. To study the crosstalk between fat and endothelial cells, human umbilical venous endothelial cells (HUVECs), and human coronary artery endothelial cells (HCAECs) were cultured in infranatants (Adipo) of primary differentiated human adipocytes. Interestingly, incubation of HUVECs and HCAECs with Adipo significantly increased monocyte adhesion 7.3 and 2.2-fold, respectively. VCAM-1, ICAM-1, and E-selectin in HUVECs were upregulated 3.9, 3.0, and 9.5-fold, respectively, under these conditions. Furthermore, Adipo significantly stimulated NFkappaB activity 1.9-fold. The NFkappaB inhibitor MG-132 and heat inactivation significantly reversed Adipo-stimulated monocyte adhesion. TNFalpha-neutralizing antibodies partly reversed Adipo-induced monocyte adhesion. In contrast, thiazolidinedione-pretreatment of human adipocytes did not alter the effects of Adipo. Adipo did not show cytotoxic effects. Taken together, we demonstrate that endothelial dysfunction is induced by adipocyte-secreted factors via NFkappaB partly dependent on TNFalpha.     

Muscle thixotropy as a tool in the study of proprioception

When a muscle relaxes after a contraction, cross-bridges between actin and myosin in sarcomeres detach, but about 1 % spontaneously form new, non-force-generating attachments. These bridges give muscle its thixotropic property. They remain in place for long periods if the muscle is left undisturbed and give the muscle a passive stiffness in response to a stretch. They are detached by stretch, but reform at the new length. If the muscle is then shortened, the presence of these bridges prevents muscle fibres from shortening and they fall slack. So, resting muscle can be in one of two states, where it presents in response to a stretch with a high stiffness, if no slack is present, or with a compliant response in the presence of slack. Intrafusal fibres of muscle spindles show thixotropic behaviour. For spindles, after a conditioning contraction, they are left stretch sensitive, with a high level of background discharge. Alternatively, if after the contraction the muscle is shortened, intrafusal fibres fall slack, leaving spindles with a low level of background activity and insensitivity to stretch. Muscle spindles are receptors involved in the senses of human limb position and movement. The technique of muscle conditioning can be used to help understand the contribution of muscle spindles to these senses and how the brain interprets signals arising in spindles. When, in a two-arm position-matching task, elbow muscles of the two arms are deliberately conditioned in opposite ways, the blindfolded subject makes large position errors of which they are unaware. The evidence suggests that the brain is concerned with the difference signal coming from the antagonists acting at the elbow and with the overall difference in signal from the two arms. Another way of measuring position sense is to use a single arm and indicate its perceived position with a pointer. Here, there is no access to a signal from the other limb, and position sense relies on referral to a central map of the body, the postural schema.     

Mirror neuron activity during contagious yawning—an fMRI study

Yawning is contagious. However, little research has been done to elucidate the neuronal representation of this phenomenon. Our study objective was to test the hypothesis that the human mirror neuron system (MNS) is activated by visually perceived yawning. We used functional magnetic resonance imaging to assess brain activity during contagious yawning (CY). Signal-dependent changes in blood oxygen levels were compared when subjects viewed videotapes of yawning faces as opposed to faces with a neutral expression. In response to yawning, subjects showed unilateral activation of their Brodmann’s area 9 (BA 9) portion of the right inferior frontal gyrus, a region of the MNS. In this way, two individuals could share physiological and associated emotional states based on perceived motor patterns. This is one component of empathy (motor empathy) that underlies the development of cognitive empathy. The BA 9 is reportedly active in tasks requiring mentalizing abilities. Our results emphasize the connection between the MNS and higher cognitive empathic functions, including mentalizing. We conclude that CY is based on a functional substrate of empathy.