Four Weeks in a Single-Leg Weight-Bearing Hip Spica Cast is Sufficient Treatment for Isolated Femoral Shaft Fractures in Children Aged 1 to 3 Years.

BACKGROUND: Hip spica casting regimens for the treatment of femoral shaft fractures in a pediatric population aged 1 to 3 years vary. Patient charts were reviewed to determine if there are any clinical differences between 3 and 4 weeks in an ambulatory single-leg hip spica (SLHS) cast versus 6 to 8 weeks in a standard double-leg, non-weight-bearing hip spica cast. METHODS: The medical records of 109 patients with femoral shaft fractures treated with a hip spica casting from January 1, 2008 to December 31, 2011 were examined. After exclusions, 94 patients were eligible for inclusion in the study. Patient records were assessed, noting age, weight, type of cast, time in cast, and complications. All casts were applied by senior pediatric orthopaedic surgeons at a single institution. RESULTS: Two groups were evaluated: 59 patients in the SLHS group and 35 in the double-leg hip spica group. The 2 groups were demographically similar with an average age of 2 years, 70.2% of patients were male, 45.7% were black, and 35.1% were white. The average time to cast removal was 4.1 weeks for the single-leg group and 5.3 weeks for the double-leg group (P<0.001). Both groups had similar low rates of loss of reduction. The double-leg group had a significantly higher incidence of clinically significant limb-length discrepancy (7/35, 20%), compared with the single-leg group (1/59, 1.7%, P=0.004). In addition, the double-leg group also had more skin problems (11/35, 31.4%) compared with the single-leg group (6/59, 10.2%, P=0.013). Seventeen patients in the single-leg group were documented as walking in the cast as compared with no patients in the double-leg group (P<0.001). CONCLUSIONS: Patients treated with a single-leg spica cast for 4 weeks had fewer complications than patients treated in a traditional double-leg cast. Femoral shaft fractures in patients less than 4 years old can be treated in a weight-bearing SLHS casts for approximately 4 weeks with fewer alignment and skin complications. LEVEL OF EVIDENCE: Level III-clinical retrospective comparative study.

Ultrasound evaluation of ulnar nerve anatomy in the pediatric population.

BACKGROUND: Ulnar nerve instability has been reported in up to 17% of children. Accurate assessment is important to achieve because of potential nerve complications that can arise from treatment of common pediatric fractures, including supracondylar humerus fractures. The objective of our study was to evaluate our ability to use ultrasonography to determine the extent of ulnar nerve dislocation in the normal pediatric population and to determine if there is a relationship between ulnar nerve instability and ligamentous laxity. METHODS: We conducted a prospective ultrasound evaluation of 51 children, examining the excursion of the ulnar nerve through full range of motion. On the basis of its movement during flexion, the ulnar nerve was categorized as stable, subluxating, or dislocating. In addition, we assessed all subjects for ligamentous laxity using the Wynne-Davies signs of joint laxity. The subjects were then divided into groups based on age or ligamentous laxity, and statistical analysis was performed. RESULTS: Most of the elbows evaluated had stable ulnar nerves (64/102, 62.7%), 27.5% (28/102) had subluxating nerves, and 9.8% (10/102) had dislocating nerves. Patients aged between 6 and 10 showed the highest rate of dislocating or subluxating nerves, with 50%, and also the highest average laxity score, 2.0. When grouped according to ligamentous laxity, patients who had multiple signs of ligamentous laxity had statistically higher numbers of subluxating and dislocating nerves (91.6%, 11/12) than those with lower laxity scores (25.6%, 10/39). CONCLUSIONS: There are a substantial number of subluxating or dislocating ulnar nerves in children, and the incidence is often bilateral. Patients with ligamentous laxity are more likely to possess unstable ulnar nerves. Ultrasound evaluation and assessment of ligamentous laxity are additional tools that can be used to assess elbow anatomy and identify children at risk for iatrogenic nerve injury. LEVEL OF EVIDENCE: Level III, diagnostic study.

Recruitment of Atg9 to the preautophagosomal structure by Atg11 is essential for selective autophagy in budding yeast.

Autophagy is a conserved degradative pathway that is induced in response to various stress and developmental conditions in eukaryotic cells. It allows the elimination of cytosolic proteins and organelles in the lysosome/vacuole. In the yeast Saccharomyces cerevisiae, the integral membrane protein Atg9 (autophagy-related protein 9) cycles between mitochondria and the preautophagosomal structure (PAS), the nucleating site for formation of the sequestering vesicle, suggesting a role in supplying membrane for vesicle formation and/or expansion during autophagy. To better understand the mechanisms involved in Atg9 cycling, we performed a yeast two-hybrid-based screen and identified a peripheral membrane protein, Atg11, that interacts with Atg9. We show that Atg11 governs Atg9 cycling through the PAS during specific autophagy. We also demonstrate that the integrity of the actin cytoskeleton is essential for correct targeting of Atg11 to the PAS. We propose that a pool of Atg11 mediates the anterograde transport of Atg9 to the PAS that is dependent on the actin cytoskeleton during yeast vegetative growth.

Atg27 is required for autophagy-dependent cycling of Atg9.

Autophagy is a catabolic pathway for the degradation of cytosolic proteins or organelles and is conserved among all eukaryotic cells. The hallmark of autophagy is the formation of double-membrane cytosolic vesicles, termed autophagosomes, which sequester cytoplasm; however, the mechanism of vesicle formation and the membrane source remain unclear. In the yeast Saccharomyces cerevisiae, selective autophagy mediates the delivery of specific cargos to the vacuole, the analog of the mammalian lysosome. The transmembrane protein Atg9 cycles between the mitochondria and the pre-autophagosomal structure, which is the site of autophagosome biogenesis. Atg9 is thought to mediate the delivery of membrane to the forming autophagosome. Here, we characterize a second transmembrane protein Atg27 that is required for specific autophagy in yeast. Atg27 is required for Atg9 cycling and shuttles between the pre-autophagosomal structure, mitochondria, and the Golgi complex. These data support a hypothesis that multiple membrane sources supply the lipids needed for autophagosome formation.

Analysis of autophagosome membrane cycling by fluorescence microscopy.

Autophagy is a physiological process functionally linked to cellular dynamics during starvation, cardiomyopathies, neurodegeneration, cellular immunity, and certain cancers. Although nearly 30 autophagy-related (ATG) genes have been identified and characterized, the molecular mechanisms of this process are only partially understood. One aspect of the pathway that has been intensely studied is the identity of the membrane source for newly formed autophagosomes. Although it occurs at a basal level, autophagy is an inducible process. The process of autophagosome formation involves recruitment and delivery of membrane and recycling of Atg proteins. Despite continuing attempts to identify the source of the autophagosome membrane, we are only recently beginning to understand the nature of autophagosome formation and the role of membrane protein cycling in this process. There now exists an assay utilizing fluorescence microscopy to monitor the localization, and therefore the movement, of membrane-associated Atg proteins. We describe here a method that allows visualization of Atg membrane proteins in order to observe their potential source membranes and also to determine the temporal order of action of other Atg proteins with regard to their movement.

Atg17 regulates the magnitude of the autophagic response.

Autophagy is a catabolic process used by eukaryotic cells for the degradation and recycling of cytosolic proteins and excess or defective organelles. In yeast, autophagy is primarily a response to nutrient limitation, whereas in higher eukaryotes it also plays a role in developmental processes. Due to its essentially unlimited degradative capacity, it is critical that regulatory mechanisms are in place to modulate the timing and magnitude of the autophagic response. One set of proteins that seems to function in this regard includes a complex that contains the Atg1 kinase. Aside from Atg1, the proteins in this complex participate primarily in either nonspecific autophagy or specific types of autophagy, including the cytoplasm to vacuole targeting pathway, which operates under vegetative growth conditions, and peroxisome degradation. Accordingly, these proteins are prime candidates for factors that regulate the conversion between these pathways, including the change in size of the sequestering vesicle, the most obvious morphological difference. The atg17delta mutant forms a reduced number of small autophagosomes. As a result, it is defective in peroxisome degradation and is partially defective for autophagy. Atg17 interacts with both Atg1 and Atg13, via two coiled-coil domains, and these interactions facilitate its inclusion in the Atg1 complex.

Peroxisome senescence in human fibroblasts.

The molecular mechanisms of peroxisome biogenesis have begun to emerge; in contrast, relatively little is known about how the organelle functions as cells age. In this report, we characterize age-related changes in peroxisomes of human cells. We show that aging compromises peroxisomal targeting signal 1 (PTS1) protein import, affecting in particular the critical antioxidant enzyme catalase. The number and appearance of peroxisomes are altered in these cells, and the organelles accumulate the PTS1-import receptor, Pex5p, on their membranes. Concomitantly, cells produce increasing amounts of the toxic metabolite hydrogen peroxide, and we present evidence that this increased load of reactive oxygen species may further reduce peroxisomal protein import and exacerbate the effects of aging.

An evaluation of supracondylar humerus fractures: is there a correlation between postponing treatment and the need for open surgical intervention?

PURPOSE: The goal of this study was to evaluate the treatment and recovery of patients treated for Gartland type III supracondylar humerus fractures in order to determine if postponing treatment leads to a higher rate of open surgical treatment or complications. METHODS: A retrospective study was conducted examining the medical records of children with Gartland type III supracondylar humerus fractures at our institution for a two-year period. The patients included in the study were treated with closed reduction and percutaneous pinning (CRPP) or open reduction and internal fixation (ORIF). RESULTS: After exclusions, 134 patients were included in the study, with an average age of 5.6 years. The patients were grouped according to whether their treatment was postponed (39.6 %) or immediate (60.4 %). The majority of all patients were treated using CRPP: 46 (86.8 %) of the postponed patients and 75 (92.6 %) of the immediate patients. Very few postsurgical complications occurred in the patients; there was only one (1.6 %) case of iatrogenic nerve injury in a postponed patient as well as four (3.8 %) cases of loss of carrying angle: one (2.3 %) in postponed patients and three (4.8 %) in immediate patients. CONCLUSIONS: Postponing treatment of type III supracondylar humerus fractures in children did not lead to an increase in open surgical treatment; nor did it lead to an increase in complications.

Postoperative pain management after spinal fusion surgery: an analysis of the efficacy of continuous infusion of local anesthetics.

Spinal fusion surgery is a major surgery that results in severe postoperative pain, therefore pain reduction is a primary concern. New strategies for pain management are currently under investigation and include multimodal treatment. A 3-year retrospective analysis of patients with idiopathic scoliosis undergoing spinal fusion surgery was performed at our hospital, assessing patient pain scores, opioid use, and recovery. We evaluated the effect of adding continuous infusion of local anesthetics (CILA) to a postoperative pain management protocol that includes intraoperative intrathecal morphine, as well as postoperative patient-controlled analgesia and oral opioid/acetaminophen combination. The study compared 25 patients treated according to the standard protocol, with 62 patients treated with CILA in addition to the pain management protocol. Patients in the CILA group used nearly 0.5 mg/kg less opioid analgesics during the first 24 hours after surgery.

Intramedullary nails for pediatric diaphyseal femur fractures in older, heavier children: early results.

PURPOSE: A common treatment for pediatric femur fractures is intramedullary nail (IMN) insertion. Elastic stable intramedullary nails (ESINs) are often used for these procedures in heavier patients, but the potential for complications and malunion is greater. We describe here a rigid IMN specifically designed for adolescents, the adolescent lateral entry femoral nail (ALFN). The purpose of this study was to compare the recovery and complications for patients treated with ESINs to those treated with the ALFN. METHODS: Our study design was a retrospective cohort study. We performed a review of medical records of 22 children ages 10-17 requiring surgical fixation of a femur fracture for a 2½-year period. Patients selected for the study had traumatic diaphyseal femur fractures and were treated with ESINs without end-caps or ALFNs. Our analyses evaluated injury, surgical, and outcome information for all patients. RESULTS: Twenty-two patients were eligible for inclusion and were divided into two groups according to their treatment: the ESIN group with 7 patients and the ALFN group with 15 patients. We then performed a comparison of complications and recovery for these patients. The mean time to full weight-bearing was significantly less for the ALFN group (4.1 weeks; SD, 2.2), than the ESIN group (9.4 weeks; SD 3.9). There was no statistical difference in the incidence of major or minor complications. CONCLUSIONS: Older, heavier pediatric patients treated for femur fracture with ALFNs had a shorter recovery time than similar patients treated with ESINs. However, the outcomes for both groups were satisfactory.

A cycling protein complex required for selective autophagy.

Survival of environmental stress conditions requires the maintenance of cellular homeostasis. To preserve this balance, cells utilize a degradative mechanism known as autophagy. During this process, in response to starvation or other stresses, bulk cytoplasm is non-specifically sequestered within double-membrane vesicles and delivered to the lysosome/vacuole for subsequent degradation and recycling. The cytoplasm to vacuole targeting (Cvt) pathway is a type of specific autophagy, which occurs constitutively during growing conditions. Here, we examine three autophagy-related (Atg) proteins, Atg9, Atg23 and Atg27, which exhibit a unique localization pattern, residing both at the pre-autophagosomal structure (PAS) and other peripheral sites. These proteins colocalize, interact with one another in vivo, and form a functional complex. Furthermore, all three proteins cycle between the PAS and the other sites, and depend upon one another for this movement. Our data suggest that Atg9, Atg23 and Atg27 play a role in Atg protein retrieval from the PAS. In addition, Atg9 and Atg27 are the only known integral membrane Atg proteins involved in vesicle formation; a better understanding of their function may offer insight into the mechanism of membrane delivery to the PAS, the site of double-membrane vesicle assembly.

Phosphorylation of the Ras-GRF1 exchange factor at Ser916/898 reveals activation of Ras signaling in the cerebral cortex.

The Ras-GRF1 exchange factor, which is regulated by increases in intracellular calcium and the release of G beta gamma subunits from heterotrimeric G proteins, plays a critical role in the activation of neuronal Ras. Activation of G protein-coupled receptors stimulates an increase in the phosphorylation of Ras-GRF1 at certain serine residues. The first of these sites to be identified, Ser(916) in the mouse sequence (equivalent to Ser(898) in the rat sequence), is required for full activation of the Ras exchange factor activity of Ras-GRF1 by muscarinic receptors. We demonstrate here that Ras-GRF1 is highly expressed in rat brain compared with the Sos exchange factor and that there is an increase in incorporation of (32)P into Ser(898) of brain Ras-GRF1 following activation of protein kinase A. Phosphorylation of Ras-GRF1 at Ser(916) is also required for maximal induction of Ras-dependent neurite outgrowth in PC12 cells. A novel antibody (termed 2152) that selectively recognizes Ras-GRF1 when it is phosphorylated at Ser(916/898) confirmed the regulated phosphorylation of Ras-GRF1 by Western blotting in both model systems of transfected COS-7 and PC12 cells and also of the endogenous protein in rat forebrain slices. Indirect confocal immunofluorescence of transfected PC12 cells using antibody 2152 demonstrated reactivity only under conditions in which Ras-GRF1 was phosphorylated at Ser(916/898). Confocal immunofluorescence of cortical slices of rat brain revealed widespread and selective phosphorylation of Ras-GRF1 at Ser(898). In the prefrontal cortex, there was striking phosphorylation of Ras-GRF1 in the dendritic tree, supporting a role for Ras activation and signal transduction in neurotransmission in this area.