Neuropeptide Y Attenuates Stress‐Induced Bone Loss Through Suppression of Noradrenaline Circuits

Chronic stress and depression have adverse consequences on many organ systems, including the skeleton, but the mechanisms underlying stress‐induced bone loss remain unclear. Here we demonstrate that neuropeptide Y (NPY), centrally and peripherally, plays a critical role in protecting against stress‐induced bone loss. Mice lacking the anxiolytic factor NPY exhibit more anxious behavior and elevated corticosterone levels. Additionally, following a 6‐week restraint, or cold‐stress protocol, Npy‐null mice exhibit three‐fold greater bone loss compared to wild‐type mice, owing to suppression of osteoblast activity. This stress‐protective NPY pathway acts specifically through Y2 receptors. Centrally, Y2 receptors suppress corticotropin‐releasing factor expression and inhibit activation of noradrenergic neurons in the paraventricular nucleus. In the periphery, they act to control noradrenaline release from sympathetic neurons. Specific deletion of arcuate Y2 receptors recapitulates the Npy‐null stress response, coincident with elevated serum noradrenaline. Importantly, specific reintroduction of NPY solely in noradrenergic neurons of otherwise Npy‐null mice blocks the increase in circulating noradrenaline and the stress‐induced bone loss. Thus, NPY protects against excessive stress‐induced bone loss, through Y2 receptor‐mediated modulation of central and peripheral noradrenergic neurons. © 2014 American Society for Bone and Mineral Research.     

Antireflux surgery for symptomatic gastroesophageal reflux: mechanism of action

To determine the effects of Nissen fundoplication upon the symptoms of reflux and the diagnostic tests employed to evaluate reflux and to examine the relationship between gastroesophageal reflux and lower esophageal sphincter pressure before and after fundoplication, 10 patients with symptomatic reflux were studied before and after operation. Clinical evaluation, barium esophagography, endoscopy with mucosal biopsy, esophageal manometry, acid-perfusion and acid-reflux testing, and gastroesophageal scintiscaning were performed on each patient before and after surgery. Following fundoplication, marked symptomatic, radiographic, endoscopic, and histologic improvement was observed. Serial acid-reflux tests at increasing gastroesophageal pressure gradients returned to normal after surgery. Lower-esophageal-sphincter (LES) pressure increased from 8.2 +/- 1.3 to 12.0 +/- 1.5 mm Hg (P less than 0.01). In addition, surgery resulted in a significant decrease in the gastroesophageal reflux index from 17.4 +/- 2.4 to 2.7 +/- 1.1% (P less than 0.001). Surprisingly, the pre- and postoperative resting LES pressures did not correlate significantly with corresponding gastroesophageal reflux indices for individual patients. We conclude that increased LES pressure alone does not explain adequately the functional and clinical improvement which follows fundoplication.     

Contracting between public agencies and private psychiatric inpatient facilities

Purchasing human services through contracts with private providers has become an increasingly common practice over the past 20 years. Using data from a national survey of psychiatric inpatient facilities, this paper examines the extent to which psychiatric units in privately controlled general hospitals and private psychiatric specialty hospitals (N = 611) participate in contractual arrangements to provide services to governmental bodies. It also examines how the likelihood of such a practice is affected by hospital characteristics (general or specialty, for profit or nonprofit) and features of hospitals' environments, including the competitiveness of the market for psychiatric inpatient care and the population's need for services in the hospital's county. The findings indicate that nonprofit psychiatric specialty hospitals were more likely than other types of hospitals to enter into such contracts, and that forces such as local competition and need for services were not predictors of such involvement. Contracting was shown to have a significant impact on the level of referrals a hospital accepted, but these levels were also affected by competition and need. Among hospitals with public contracts, referral acceptance from public agencies was unaffected by these factors, but they did have a significant effect on referral acceptance by hospitals without public contracts. These data suggest that public agencies contracting for services with private hospitals may represent a means by which "public sector" patients may gain access to private providers. Further, this mechanism may impose sufficient structure and regulation on the acceptance of such patients that many concerns of hospital administrators regarding patients who are costly and difficult to treat and discharge can be allayed.     

The use of vacuum-assisted closure in spinal wound infections with or without exposed dura

Introduction

The treatment of postoperative deep spinal wound infection involves debridement and intravenous antibiotics. Authors have previously reported success in a small series of patients treated with vacuum-assisted closure (VAC) therapy, but its use over exposed dura is controversial and the outcome has not been reported in large series.

Purpose

To review the outcomes following the treatment of postoperative spinal infections with VAC therapy, particularly those with exposed dura.

Methods

This is a review of prospectively collected data in 42 patients, all of whom had deep postoperative spinal infections. 30 of these patients had exposed dura. All patients had an initial debridement followed by application of VAC Whitefoam (with exposed dura) or grey Granufoam (where no dura was exposed). Pressure was set at 50 mmHg with exposed dura or 125 mmHg where no dura was exposed. All patients underwent a minimum 6 week course of antibiotics. We report on the number of visits to theatre required for dressing changes and debridement and the eventual outcomes.

Results

Five patients required a flap reconstruction. Two patients died before definitive final closure due to other complications (pneumonia and stroke). In all the other patients, their wounds healed fully. A mean of 2.3 infection surgeries were required to eradicate infection and achieve wound closure.

Conclusions

This is one of the largest studies which confirms the safety and efficacy of VAC dressings in patients with spinal wound infections, even when the dura is exposed.

Graphical abstract

These slides can be retrieved under Electronic Supplementary Material.

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