Peripheral nerve sheath tumors of the foot and ankle.

BACKGROUND: Peripheral nerve sheath tumors (PNSTs) are soft tissue neoplasms found in intimate association with a peripheral nerve. They are rarely seen in the foot and ankle where they have an innocuous appearance, but these tumors have the potential to become malignant. This study reports a large series of foot and ankle PNSTs surgically treated at a single institution. MATERIALS AND METHODS: Retrospectively, all cases of PNSTs confirmed by biopsy and surgically treated from 1992 to 2008 were included in the study. Preoperative, perioperative and postoperative variables were collected. Foot and ankle tumors were compared with the overall group of PNSTs. Fisher's test and Student's t-test were implemented to address the significance of the findings (p ≤ 0.05). RESULTS: From all PNSTs identified (n = 137), there were 14 (10.2%) foot and ankle. A painful mass was the most common presenting symptom. Schwannoma represented the most common histologic type. Two cases of malignant foot and ankle PNSTs were identified. Foot and ankle PNSTs were significantly smaller in size and showed fewer postoperative neurologic deficits than the overall group of PNSTs. No differences were found in terms of histologic type distribution, age at diagnosis, duration of symptoms and postoperative tumor recurrence, but there was a preponderance of females in this series of foot and ankle tumors. CONCLUSION: PNSTs of the foot and ankle usually present as innocuous, slow-growing masses leading to misdiagnosis and suboptimal surgical treatment of a potentially malignant lesion. A comprehensive diagnostic evaluation, preoperative planning and meticulous surgical excision are required to prevent tumor recurrence and minimize the incidence of postoperative sequelae, thus improving postoperative functional outcomes.

The surgical management of symptomatic peripheral nerve sheath tumors.

OBJECTIVE: To determine the clinical presentation and morbidity of the surgical management of peripheral nerve sheath tumors (PNSTs). METHODS: We performed a retrospective chart review of surgically treated PNSTs at the University of Miami between 1991 and 2008. RESULTS: There were a total of 140 cases, including 87 schwannomas, 34 neurofibromas, and 19 malignant peripheral nerve sheath tumors (MPNSTs). The average age of the total study group was 49.0 years; it was significantly lower for patients with neurofibroma. There was a high correlation between neurofibroma tumors and neurofibromatosis-1. Most patients with benign tumors presented with a painful mass, paresthesias, or numbness without significant weakness. Patients who had previously undergone attempted resections and preoperative biopsy had a significantly increased risk (41%) for developing postoperative neurologic deficits when compared with patients who presented with de novo tumors (15%). Intraoperative monitoring appeared to reduce the risk of postoperative motor deficit, particularly in neurofibromas. Most MPNSTs (>80%) were diagnosed at stage IIB or higher and had a combined mortality rate of 31.6% at 78 months. Tumor size was the best predictor of adverse outcome, as all MPNST mortalities occurred in patients with a tumor size of more than 7 cm. CONCLUSION: PNSTs are a heterogeneous group of lesions. Benign tumors respond well to marginal excision, whereas MPNSTs are aggressive sarcomas that require multimodal management. There was a significantly increased risk of postoperative neurologic deficits in patients who had undergone a previous biopsy, and thus tertiary referral without biopsy is recommended when a PNST is suspected.

Use of all-pedicle-screw constructs in the treatment of adolescent idiopathic scoliosis.

All-pedicle-screw constructs are safe and biomechanically advantageous in the management of adolescent idiopathic scoliosis. Safe and reproducible placement of thoracic pedicle screws is dependent on a thorough understanding of normal and abnormal anatomy, meticulous technique, and the use of neuromonitoring and fluoroscopy. Improvement in the biomechanical properties secondary to the use of pedicle screw fixation has led to shorter fusions with improved deformity correction. Coronal, sagittal, and rotational correction is superior to that obtained with hook instrumentation. Improved derotation may decrease the need for thoracoplasty, thus eliminating the risk of associated morbidity. Superior control of the deformity with all-pedicle-screw fixation, as well as the use of adjunctive posterior releases, often obviates the need for an anterior approach, even in severe curves measuring 70 degrees to 100 degrees . Improved correction, shorter fusion, and the lower morbidity associated with posterior-only approaches may compensate for higher implant costs.

Replacement of bone marrow by bone in rat femurs: the bone bioreactor.

During development and repair of bone, two distinct yet complementary mechanisms, intramembranous and endochondral, mediate new bone formation via osteoblasts. Because mechanical bone marrow ablation leads to the rapid and transient formation of new bone in the marrow cavity, we postulated that parathyroid hormone (PTH), which is a bone anabolic hormone, enhances the formation of new bone that forms after marrow ablation. We subjected the left femur of rats to mechanical marrow ablation, or sham operation, and injected the animals daily with PTH or vehicle for 1, 2, or 3 weeks in a first experiment, then with PTH, parathyroid hormone-related peptide (PTHrP), or vehicle for 3 weeks in a second experiment. We subjected both femurs from each rat to soft X-ray, peripheral quantitative computed tomography, computed tomography on a microscale, and histological analysis, and determined the concentration of serum osteocalcin. In addition, in the second experiment, we determined the serum concentration of calcium, tartrate-resistant acid phosphatase (TRAP), and receptor activator of NF-kappaB ligand (RANKL) at 3 weeks, and subjected femurs to biomechanical testing. Following treatment with PTH or PTHrP for 3 weeks, bone filled the marrow cavity of the shafts whose marrow had been ablated. PTH increased trabecular density in the right femur, but failed to induce bone formation in the medullary region of the right unoperated femoral shafts. The newly formed bone endowed left femoral shafts with improved biomechanical properties when compared to those of right femurs and left femurs from control, sham-operated, and vehicle-treated rats. PTHrP, like PTH, increased serum osteocalcin, but neither increased serum calcium, TRAP, or RANKL at 3 weeks. Our results reveal that the newly formed bone that follows marrow ablation is responsive to PTH, expand the role of PTH in bone, and might open new avenues of investigations to the field of regenerative medicine and tissue engineering. Local bone marrow removal in conjunction with pharmacologic intervention with an anabolic agent might provide a technique for rapid preferential site-directed bone growth in areas of high bone loss.

CD200 and its receptor, CD200R, modulate bone mass via the differentiation of osteoclasts.

Fusion of macrophages is an essential step in the differentiation of osteoclasts, which play a central role in the development and remodeling of bone. Osteoclasts are important mediators of bone loss, which leads, for example, to osteoporosis. Macrophage fusion receptor/signal regulatory protein alpha (MFR/SIRPalpha) and its ligand CD47, which are members of the Ig superfamily (IgSF), have been implicated in the fusion of macrophages. We show that CD200, which is not expressed in cells that belong to the myeloid lineage, is strongly expressed in macrophages at the onset of fusion. By contrast, the CD200 receptor (CD200R), which, like CD200, belongs to the IgSF, is expressed only in cells that belong to the myeloid lineage, including osteoclasts, and in CD4+ T cells. Osteoclasts from CD200-/- mice differentiated at a reduced rate. Activation of the NF-kappaB and MAP kinase signaling pathways downstream of RANK, a receptor that plays a central role in the differentiation of osteoclasts, was depressed in these cells. A soluble recombinant protein that included the extracellular domain of CD200 rescued the fusion of CD200-/- macrophages and their activation downstream of RANK. Conversely, addition of a soluble recombinant protein that included the extracellular domain of CD200R or short-hairpin RNA-mediated silencing of the expression of CD200R prevented fusion. Thus CD200 engagement of the CD200R at the initiation of macrophage fusion regulated further differentiation to osteoclasts. Consistent with in vitro observations, CD200-/- mice contained fewer osteoclasts and accumulated more bone than CD200+/+ mice. The CD200-CD200R axis is therefore a putative regulator of bone mass, via the formation of osteoclasts.

How much calcium is in your drinking water? A survey of calcium concentrations in bottled and tap water and their significance for medical treatment and drug administration.

INTRODUCTION: Different forms of water vary in calcium content. High divalent ion (i.e., Ca(2+), Mg(2+), etc.) concentration is deleterious to the absorption and efficacy of the bisphosphonate group of drugs in osteoporosis treatment. Water with high calcium concentration may also present an alternate pathway of calcium administration. In either case, knowing the actual concentration is critical. HYPOTHESIS: The current paper is a surveillance study. We hypothesize that there is considerable variation in the calcium concentrations in the various water sources: tap water from US and Canadian cities of different regions and purified, spring, and mineral bottled waters. In addition, we hypothesize that the water filter removes a significant amount of minerals including calcium from the water. METHODOLOGY: Calcium concentrations in various city tap waters, as well as an assorted number of bottled waters, were determined through the direct inspection of scientific data. The effect of filtering was also determined by mineral analysis of mineral water directly before and after filtration. RESULT: The calcium concentration of water varies from 1 to 135 mg/L across the USA and Canada. Most spring waters were found to have a relatively low calcium concentration, with an average of 21.8 mg/L. Purified waters contain a negligible calcium concentration. Mineral waters, on the other hand, were generally found to contain higher calcium concentrations, an average of 208 mg/L of calcium. Filtration was found to remove a considerable amount of calcium from the water, removing 89% on average. CONCLUSION: Calcium concentration in water varied substantially from different sources in the USA and Canada. Bottled waters presented with concentrations of calcium covering a very large range. Certain tap and bottled waters present with concentrations of calcium sufficient to exhibit a deleterious effect on bisphosphonate treatment. Alternatively, certain waters may be used as a source of calcium that may provide over 40% of the recommended daily intake for calcium.

IL-1 receptor-associated kinase M is a central regulator of osteoclast differentiation and activation.

Osteoporosis is a serious problem worldwide; it is characterized by bone fractures in response to relatively mild trauma. Osteoclasts originate from the fusion of macrophages and they play a central role in bone development and remodeling via the resorption of bone. Therefore, osteoclasts are important mediators of bone loss that leads, for example, to osteoporosis. Interleukin (IL)-1 receptor (IL-1R)-associated kinase M (IRAK-M) is only expressed in cells of the myeloid lineage and it inhibits signaling downstream of IL-1R and Toll-like receptors (TLRs). However, it lacks a functional catalytic site and, thus, cannot function as a kinase. IRAK-M associates with, and prevents the dissociation of, IRAK-IRAK-4-TNF receptor-associated factor 6 from the TLR signaling complex, with resultant disruption of downstream signaling. Thus, IRAK-M acts as a dominant negative IRAK. We show here that mice that lack IRAK-M develop severe osteoporosis, which is associated with the accelerated differentiation of osteoclasts, an increase in the half-life of osteoclasts, and their activation. Ligation of IL-1R or TLRs results in hyperactivation of NF-kappaB and mitogen-activated protein kinase signaling pathways, which are essential for osteoclast differentiation. Thus, IRAK-M is a key regulator of the bone loss that is due to osteoclastic resorption of bone.

Arthroscopic removal of bullet fragments from the subacromial space of the shoulder.

This article describes a case of arthroscopic removal of a bullet fragment from the subacromial space. The bullet tore the rotator cuff and imbedded itself on the inferior surface of the acromion, producing pain and impingement. The bullet was removed, and the rotator cuff repaired arthroscopically. The patient noted complete relief of pain and improved range of motion.

El gas sarin: efecto y tratamiento, recientes investigaciones / Sarin gas: Effect and treatment, recent researches

El febrero de este mismo año, el mundo se estremeció ante los ataques terroristas presuntamente perpetrados por miembros de la secta extremista AumShinkyi. Fueron dejados paquetes en diversas estaciones del metro de Tokio y estos comenzaron a exhalar un olor indescriptible, pero que producía efectos terribles en los transeúntes. Todos intentaron alejarse del gas, pero algunos no lograron hacerlo a tiempo ¿Qué era esa sustancia que de un momento a otro podía atacar a las grandes masas que utilizan el metro? Era Sarin, un gas tóxico muy fácil de sintetizar que ha sido adoptado por muchos países como principal arma química. Ahora el Sarin se convierte en una amenaza terrorista...