Bioabsorbable tacks for arthroscopic treatment of recurrent anterior shoulder dislocation

The inflammatory process and autoimmunity in the form of antibodies to oxidized LDL are important factors in the formation of the atherosclerotic plaque. We examined the time relationship of oxidized lipoprotein antibodies to the acute oxidative stress of myocardial infarction (MI). We also examined the relationship of C-reactive protein, an index of inflammation, and therefore of free radical production, to oxidized low-density lipoprotein (LDL) antibodies. We examined five groups of patients in a cross-sectional study: group 1, within 48 h of MI; group 2, two days to 1 week; group 3, 1-4 weeks; group 4, 1-3 months; and group 5, 3-6 months post MI. Nine patients with high antibody levels were re-examined 12 months after their first assessment. Malondialdehyde (MDA)-LDL and MDA-HDL antibodies were determined by an ELISA method. The highest MDA-LDL antibodies were found within 48 h of MI, but there was no significant difference in MDA-HDL antibodies between the groups. When 9/10 patients with LDL antibodies greater than the mean of 2.7 were re-examined 1 year later, there was a significant decrease in the mean antibody levels (5.2 +/- 1.7 vs. 3.2 +/- 0.6, p < 0.02). There was no correlation between antibodies to MDA-LDL and antibodies to MDA-HDL. There was a positive correlation between serum HDL cholesterol and antibodies to MDA-LDL (r = 0.4, p < 0.02) and a positive correlation between serum triglycerides and MDA-HDL antibodies (r = 0.39, p < 0.02). Acute MI appears to be associated with significantly higher C-reactive protein and antibodies to MDA-LDL, suggesting a possible acceleration of the atherosclerotic process immediately prior to MI.     

Free flow acoustophoresis: microfluidic-based mode of particle and cell separation

A novel method, free flow acoustophoresis (FFA), capable of continuous separation of mixed particle suspensions into multiple outlet fractions is presented. Acoustic forces are utilized to separate particles based on their size and density. The method is shown to be suitable for both biological and nonbiological suspended particles. The microfluidic separation chips were fabricated using conventional microfabrication methods. Particle separation was accomplished by combining laminar flow with the axial acoustic primary radiation force in an ultrasonic standing wave field. Dissimilar suspended particles flowing through the 350-microm-wide channel were thereby laterally translated to different regions of the laminar flow profile, which was split into multiple outlets for continuous fraction collection. Using four outlets, a mixture of 2-, 5-, 8-, and 10-microm polystyrene particles was separated with between 62 and 94% of each particle size ending up in separate fractions. Using three outlets and three particle sizes (3, 7, and 10 microm) the corresponding results ranged between 76 and 96%. It was also proven possible to separate normally acoustically inseparable particle types by manipulating the density of the suspending medium with cesium chloride. The medium manipulation, in combination with FFA, was further used to enable the fractionation of red cells, platelets, and leukocytes. The results show that free flow acoustophoresis can be used to perform complex separation tasks, thereby offering an alternative to expensive and time-consuming methods currently in use.     

Injuries in the adolescent porcine spine exposed to mechanical compression

STUDY DESIGN: An experimental porcine study in which functional lumbar spinal units were tested in compression to failure. Biomechanical, radiographic, magnetic resonance imaging, and histological characteristics are described. OBJECTIVES: To explain the different patterns of injury seen in adults and adolescents resulting from traumatic injury to the vertebrae and to explain the mechanism behind traumatic displacement of the ring apophysis seen in athletes. SUMMARY OF BACKGROUND DATA: Recent investigations of the spine in adolescent who have sustained trauma have shown injuries to the growth zone, whereas studies of adults have shown injuries to the vertebral body. A higher frequency of abnormalities in the discs, the vertebral bodies, the endplates, and the ring apophyses has been demonstrated in athletes with high loads on the spine. There is controversy over the etiology of these changes. METHODS: Twelve functional lumbar spinal units (vertebra-disc-vertebra) obtained from six young male pigs were tested in compression to failure. All units were examined with plain radiography and magnetic resonance imaging before and after compression. After the compression, histologic samples were taken from the injury site. RESULTS: Identical traumatic changes were seen in all functional lumbar spinal units, i.e., fracture in the endplate through the growth zone posteriorly and displacement of the anulus fibrosus with a bony fragment at the point of insertion of the vertebra. The nucleus pulposus was ruptured and displaced through the fracture line in all cases. The injuries were not seen on radiographs but were detected on magnetic resonance images, as confirmed on microscopic and histologic examination. CONCLUSION: This study shows that the weakest part of the lumbar spine of the juvenile pig, when compressed, is the growth zone and the junction between the point of insertion of the anulus fibrosus and the vertebra. This location of weakness may explain the high frequency of disc degeneration and "persisting apophysis" seen in the spine of athletes.