The Dorsal Aponeurosis of the Thumb.

PURPOSE: To evaluate the thumb dorsal aponeurosis anatomy. Consideration of structural differences between the fingers and thumb will provide an improved clinical understanding of the thumb dorsal aponeurosis anatomy. METHODS: Ten fresh cadaver hands from 5 patients with an average age of 31.6 (range, 22-41) years were dissected. The thenar muscles were identified and insertion sites were documented. The fibers of the dorsal aponeurosis and contributions were identified. RESULTS: The flexor pollicis brevis superficial head contributed to the radial fibers of the dorsal aponeurosis in 8 specimens and contributed to the deep head in 1 specimen. The abductor pollicis brevis provided fibers to the radial dorsal aponeurosis in all 10 specimens. The oblique and transverse heads of the adductor pollicis contributed to the ulnar dorsal aponeurosis in 8 and 9 hands, respectively. The fibers of the intrinsic apparatus were composed of 3 major types: transverse, oblique, and long. CONCLUSIONS: This investigation provides a detailed anatomic study of the dorsal aponeurosis of the thumb with observation of both intrinsic and extrinsic contributions. CLINICAL RELEVANCE: Understanding the anatomy of the dorsal aponeurosis of the thumb remains important not only for evaluation of the classic Stener lesion, but also for the appropriate treatment of deformity, contracture, and neuromuscular disorders involving the thumb.

Anterior Spinal Surgery Involving Variant Vascular Anatomy: A Case Report.

STUDY DESIGN: Case report of an anterior approach to the spine in the setting of variant vascular anatomy. OBJECTIVE: To highlight the importance of evaluating vascular anatomy before anterior lumbar spine surgery. SUMMARY OF BACKGROUND DATA: A 62-year-old woman with idiopathic scoliosis had thoracolumbar fusion in adolescence and subsequently developed symptomatic sub-adjacent segment breakdown. Vascular complications may be encountered during anterior approaches to the spine. Variation in vascular anatomy may compound the difficulty of an already meticulous dissection. RESULTS: A patient with idiopathic scoliosis who had thoracolumbar fusion in adolescence and subsequently developed symptomatic sub-adjacent segment breakdown. She underwent a 2-stage posterior/anterior procedure. During the anterior retroperitoneal approach, an anomalous left inferior vena cava was encountered that required tedious dissection for safe and adequate exposure of the lumbar spine. CONCLUSIONS: When planning anterior lumbar spine surgery, careful review of the vascular anatomy on imaging should be performed. This will help prepare the surgeon for more complex or anomalous anterior anatomy. If atypical vascular anatomy is identified, consideration of a pathologic cause should be investigated.

Increasing the elution of vancomycin from high-dose antibiotic-loaded bone cement: a novel preparation technique.

BACKGROUND: Antibiotic bone cement is commonly used in staged revision arthroplasty as well as the treatment of open fractures. Multiple factors affect antibiotic elution from bone cement. This study was performed to investigate the effect of two variables, the quantity of liquid monomer and the timing of antibiotic addition, on the ultimate elution of antibiotic from bone cement. METHODS: Vancomycin-loaded Simplex P and SmartSet MV bone cement was prepared with three different methods: a common surgical technique, a mixing technique that doubled the amount of liquid monomer, and a novel technique that delayed antibiotic addition until after thirty seconds of polymerization. Cylinders of a standardized size were created from each preparation. The elution profiles of five cylinders from each preparation were measured over six weeks with use of high-performance liquid chromatography. Cylinders were tested in compression to quantify strength. RESULTS: Delayed antibiotic addition resulted in significantly greater cumulative elution over six weeks (p < 0.0001), with minimal reduction in strength, compared with the other groups. Doubling the liquid monomer significantly reduced cumulative elution over six weeks compared with either of the other techniques (p < 0.0001). Vancomycin elution from Simplex P was 52%greater and vancomycin elution from SmartSet MV was 25% greater in the delayed-antibiotic-addition groups than it was in the corresponding standard surgical technique groups. The majority of the antibiotic was released over the first week in all groups. : High-dose-antibiotic bone cement prepared with delayed antibiotic addition increased vancomycin elution compared with the standard surgical preparation. Incorporating additional liquid monomer decreased vancomycin elution from high-dose-antibiotic cement. We recommend preparing high-dose-antibiotic bone cement with the delayed-antibiotic addition technique and not incorporating additional liquid monomer. CLINICAL RELEVANCE: Both the relative volume of liquid monomer and the timing of antibiotic addition have substantial effects on the elution of antibiotic from bone cement.

Heritability of plasma amino acid levels in different nutritional states.

Significant heritability has been shown for several plasma amino acid levels, but the results may have been confounded by sampling in a variety of nutritional states. We studied a group of families on a low protein steady-state diet in fasting and non-fasting states. Heritability of individual amino acids varied according to the nutritional state, suggesting the amount of genetic and environmental influences differ among the operative systems that control individual amino acid homeostasis throughout the feed/fast cycle.

Dynamic assembly of the urokinase-type plasminogen activator signaling receptor complex determines the mitogenic activity of urokinase-type plasminogen activator.

The urokinase-type plasminogen activator (uPA) receptor (uPAR) functions in concert with co-receptors, including integrins, FPR-like receptor-1/lipoxin A4 receptor, and the epidermal growth factor receptor (EGFR), to initiate cell signaling. uPAR co-receptors may be dynamically organized into a multiprotein signaling receptor complex. In Chinese hamster ovary-K1 (CHO-K1) cells, uPA-binding to uPAR activates ERK/MAP kinase, even though these cells do not express the EGFR; however, when CHO-K1 cells are transfected to express the EGFR, ERK activation becomes EGFR-dependent. In this study, we demonstrate that ERK activation in response to uPA follows equivalent biphasic kinetics in EGFR-expressing and -deficient CHO-K1 cells. In both cell types, the response is pertussis toxin-sensitive; however, uPA promotes cell proliferation exclusively in the EGFR-expressing cells. uPA-induced mitogenic activity requires activation of both STAT5b and ERK. STAT5b was tyrosine-phosphorylated, in response to uPA, only in EGFR-expressing cells. uPA-induced cell proliferation was blocked by dominant-negative MEK1, dominant-negative STAT5b, and by expression of an EGFR that is mutated at Tyr-845, which is essential for STAT5b activation. In two cell culture models of uPA-stimulated breast cancer growth, MDA-MB 468 cells treated with uPA and MCF-7 cells treated with uPA-plasminogen activator inhibitor-1 complex, proliferation was completely inhibited when EGFR expression or activity was blocked. We conclude that expression and assembly of uPAR co-receptors in a specific cell type determines the response to uPA. The EGFR selectively cooperates with uPAR to mediate mitogenesis.