The biomechanical analysis of a tendon fixation device for flexor tendon repair

PURPOSE: Stainless steel suture is high in tensile strength but is not widely used in flexor tendon repair because of difficulty with handling and knot tying. The purpose of this study was to examine the biomechanical characteristics of the single-strand multifilament stainless steel Teno Fix device (Ortheon Medical, Winter Park, FL) designed for zone II flexor digitorum profundus (FDP) tendon repair. METHODS: Sixty cadaveric flexor tendons were transected and randomized to receive a Teno Fix or 4-stranded (3-0 or 4-0 braided polyester) suture repair; all repairs were tested with and without a 5-0 monofilament polypropylene circumferential epitendinous suture. By using a material testing system all tendons were tested to failure in tension using a linear model with a loading rate of 1 mm/s. Stiffness, force, and energy at both 2-mm gap and peak force were calculated from the resulting force-displacement curves. RESULTS: The 2-mm gapping force was significantly greater for the Teno Fix and the 3-0 repairs than for the 4-0 repairs. The energy absorbed up to 2-mm gap was significantly greater for the Teno Fix, however, than for all suture repairs both with and without a circumferential suture. There was no statistically significant difference in peak force or energy absorbed at peak force between the Teno Fix and suture repairs; the average gap at peak force for all repairs was 5.2 mm. The addition of a circumferential suture increased the 2-mm gapping and peak forces of the Teno Fix repair to 54.5 N and 66.7 N, respectively. CONCLUSIONS: Increased strength and energy absorbed at 2-mm gap and ease of installation makes the Teno Fix a promising repair method.     

The rise and fall of priming: how visual exposure shapes cortical representations of objects

How does the amount of time for which we see an object influence the nature and content of its cortical representation? To address this question, we varied the duration of initial exposure to visual objects and then measured functional magnetic resonance imaging (fMRI) signal and behavioral performance during a subsequent repeated presentation of these objects. We report a novel 'rise-and-fall' pattern relating exposure duration and the corresponding magnitude of fMRI cortical signal. Compared with novel objects, repeated objects elicited maximal cortical response reduction when initially presented for 250 ms. Counter-intuitively, initially seeing an object for a longer duration significantly reduced the magnitude of this effect. This 'rise-and-fall' pattern was also evident for the corresponding behavioral priming. To account for these findings, we propose that the earlier interval of an exposure to a visual stimulus results in a fine-tuning of the cortical response, while additional exposure promotes selection of a subset of key features for continued representation. These two independent mechanisms complement each other in shaping object representations with experience.     

Renal pelvis volume during diuresis in children with hydronephrosis: implications for diagnosing obstruction with diuretic renography

PURPOSE: We measured the volume of the renal pelvis during diuretic renography (DR) in children with normal and hydronephrotic kidneys to determine if changes in pelvic volume could affect the accuracy of DR in diagnosing obstruction. MATERIALS AND METHODS: We studied 18 patients 1 month to 10 years old with unilateral hydronephrosis ultimately proved to be either obstructive or nonobstructive. Simultaneous DR and ultrasound were performed with patients supine using the gamma camera. Ultrasound measurements of the renal pelvis in 3 dimensions, obtained before and at intervals after diuretic injection, were used to calculate renal pelvic volume. The contralateral normal kidneys were used as controls. RESULTS: Between 15 and 60 minutes after diuretic injection the renal pelvis enlarged to a maximum volume in all hydronephrotic and normal kidneys and then gradually decreased in size. Mean average increase in volume for hydronephrotic kidneys ranged from 46% in obstructed kidneys to 88% in nonobstructed kidneys. Volume expansion caused dilution of isotope within the renal pelvis, which resulted in prolongation of elimination half-time (T1/2) in 42% of nonobstructed hydronephrotic kidneys sufficient to register an obstructed washout pattern. However, there were no differences in the initial pelvic volume or the rate or extent of increases or decreases in pelvic volume that would permit nonobstructed hydronephrotic kidneys to be distinguished from obstructed ones. CONCLUSIONS: The renal pelvis enlarges during diuresis in children with hydronephrosis. This enlargement causes dilution of isotope within the renal pelvis during DR, which prolonged the isotope washout rate or T1/2 sufficiently to produce an obstructed washout pattern in more than 40% of hydronephrotic kidneys that were ultimately proved to be nonobstructed. This misdiagnosis of obstruction is particularly likely to occur in children younger than 2 years because pelvic volume expansion is so exaggerated. Consequently, T1/2 appears to be particularly vulnerable to inaccuracy in diagnosing obstruction in this age group, and, therefore, it should not be relied on as an operative determinant.     

Social support and depressive symptomatology among HIV-positive women: the mediating role of self-esteem and mastery

Women constitute an increasing proportion of individuals contracting HIV in the United States and, once diagnosed, are living longer lives since the advent of combination antiretroviral therapies. HIV-positive women, who are disproportionately ethnic minority, face unique challenges to their psychosocial adaptation. Findings from a survey of 373 mainly indigent African-American and Puerto Rican women living with HIV/AIDS in the New York City area indicated high levels of depressive symptomatology, which were inversely related to HIV-related social support from friends, relatives, partner, and groups/ organizations. In line with the Cognitive Adaptation Model, structural equation modeling indicated that psychological resourcefulness (i.e., self-esteem and mastery) mediated the effects of social support on depressive symptomatology. Findings suggest the need to assess HIV-positive women for social isolation and depression and to provide them with interventions such as support groups that capitalize on their existing strengths, including their psychological resourcefulness.     

Advocacy to action: addressing coordinated school health program issues with school boards

As the need for Coordinated School Health Programs (CSHP) increases, so does recognition of the importance for advocating with local school boards for their support. Identifying the diversified make up of school board members and implementing effective strategies to advocate for coordinated school health can help facilitate the successful inclusion of such a program. With increasing emphasis placed on standardized testing and the "basic" curriculum, school board members need to become aware of specific benefits a CSHP can provide their district. With the relationship between health status and academic achievement confirmed in scientific research, school boards may begin paying more attention to providing high-quality health services and health instruction for students. This article presents items to consider and steps to take before, during, and after addressing a local school board for their support in implementing a CSHP.     

Variable sensitivity to noxious heat is mediated by differential expression of the CGRP gene

Heat sensitivity shows considerable functional variability in humans and laboratory animals, and is fundamental to inflammatory and possibly neuropathic pain. In the mouse, at least, much of this variability is genetic because inbred strains differ robustly in their behavioral sensitivity to noxious heat. These strain differences are shown here to reflect differential responsiveness of primary afferent thermal nociceptors to heat stimuli. We further present convergent behavioral and electrophysiological evidence that the variable responses to noxious heat are due to strain-dependence of CGRP expression and sensitivity. Strain differences in behavioral response to noxious heat could be abolished by peripheral injection of CGRP, blockade of cutaneous and spinal CGRP receptors, or long-term inactivation of CGRP with a CGRP-binding Spiegelmer. Linkage mapping supports the contention that the genetic variant determining variable heat pain sensitivity across mouse strains affects the expression of the Calca gene that codes for CGRPalpha.     

p130Rb2 and p27kip1 cooperate to control mobilization of angiogenic progenitors from the bone marrow

Neoangiogenesis involves both bone marrow-derived myelomonocytic and endothelial progenitor cells as well as endothelial cells coopted from surrounding vessels. Cytokines induce these cells to proliferate, migrate, and exit the cell cycle to establish the vasculature; however, which cell cycle regulators play a role in these processes is largely unknown. Here, we report that mice lacking the cell cycle inhibitors p130 and p27 show defects in tumor neoangiogenesis, both in xenografts and spontaneously arising tumors. This defect is associated with impaired mobilization of endothelial and myelomonocytic angiogenic progenitors from the bone marrow. This article documents the role of these molecules in angiogenesis and further suggests that cell expansion and mobilization from the bone marrow of angiogenic precursors are separable events.     

Quantitative in vitro phosphor imaging using [3H] and [18F] radioligands: the effects of chronic desipramine treatment on serotonin 5-HT2 receptors

Traditionally, autoradiography of neuroreceptors is performed in vitro using tritiated ligands and low sensitivity X-ray film, requiring long exposure times. In vivo imaging of neuroreceptors using positron emission tomography (PET) suffers poor spatial resolution, but in vitro PET autoradiography is difficult with film due to the short half-life of the isotopes. Storage phosphor screens provide an extremely sensitive alternative to film. To demonstrate and validate quantitative in vitro phosphor imaging with PET and tritiated ligands, we treated rats chronically with the antidepressant desipramine, which results in decreased binding to serotonin 5-HT(2) receptors. Serotonin 5-HT(2) binding decreased significantly in all cortical regions examined as measured by both [(3)H]ketanserin and [(18)F]setoperone. The data from the two radioligands were not significantly different, and the distribution of the receptors was in agreement with previous reports. We also present data on the reusability of tritium-sensitive phosphor screens, and show that the use of simple corrections allows receptor binding data with PET ligands to be compared across different days. The results indicate that phosphor imaging is a valid, fast, and quantifiable technique for measuring neuroreceptor regulation, and that it provides an excellent tool to corroborate in vivo PET data in vitro at higher resolution.     

Diffuse FDG shoulder uptake on PET is associated with clinical findings of osteoarthritis

OBJECTIVE: Our objective was to examine the degree and pattern of (18)F-FDG uptake within the shoulder as a potential marker of joint inflammation or injury. SUBJECTS AND METHODS: Twenty-four patients undergoing (18)F-FDG PET for clinical oncologic assessment completed questionnaires regarding history of shoulder disease, trauma, pain, and/or functional impairment. Thorough physical examination of the shoulder was performed. A clinical diagnosis of specific shoulder derangement or normal was established for each patient. PET scans were evaluated blindly by a nuclear medicine physician and a musculoskeletal radiologist qualitatively for location, distribution, and intensity of shoulder uptake. Standardized uptake values (SUV) were measured. RESULTS: Twenty-one patients had shoulder PET findings. Fourteen had clinical findings consistent with a specific diagnosis in the PET-positive shoulder. The remaining seven PET-positive patients were clinically normal. Three recognizable patterns of uptake were appreciable. Eight of 10 patients with diffuse uptake had findings of osteoarthritis (n = 7) or bursitis (n = 1). Two of four patients with focal greater tuberosity uptake had findings of rotator cuff injury. Two of four patients with focal glenoid uptake had findings of frozen shoulder. SUV showed a positive correlation with subject age (p < 0.01), but no association with clinical findings was identified. CONCLUSION: The pattern of FDG uptake within the shoulder may point to specific clinical entities. While focal uptake is less reliably related to clinical findings, diffuse uptake is associated with signs and symptoms of osteoarthritis or bursitis.