Is gentamicin safe and effective for severe community-acquired pneumonia? An 8-year retrospective cohort study

Gram-negative bacilli are the causative organisms in a significant proportion of patients with severe community-acquired pneumonia (CAP) admitted to the intensive care unit (ICU). Clinical guidelines recommend broad-spectrum antimicrobials for empirical treatment despite alarming global trends in antimicrobial resistance. In this study, we aimed to assess the safety and efficacy of gentamicin, an aminoglycoside with potent bactericidal activity, for empirical Gram-negative coverage of severe CAP in patients admitted to the ICU. A retrospective cohort study was performed at a university teaching hospital where the severe CAP guideline recommends penicillin, azithromycin and gentamicin as empirical cover. Ceftriaxone plus azithromycin is used as an alternative. Adults with radiologically-confirmed severe CAP were included, comparing those who received gentamicin in the first 72?h of admission with those who did not. Participants were identified using ICD-10 codes for bacterial pneumonia and data manually extracted from electronic medical records. Of 148 patients admitted with severe pneumonia, 117 were given at least one dose of gentamicin whereas the remaining 31 were not. The two groups were well matched in terms of demographics, co-morbidities and disease severity. There were no significant differences between the gentamicin and no-gentamicin groups in the incidence of acute kidney injury [60/117 (51%) vs. 16/31 (52%), respectively], hospital mortality [20/117 (17%) vs. 7/31 (23%)] and secondary outcomes including relapse and length of hospital stay. In conclusion, gentamicin is safe and has similar outcomes to alternative Gram-negative antimicrobial regimens for empirical coverage in severe CAP patients admitted to the ICU.     

Surgical delivery of drug releasing poly(lactic-co-glycolic acid)/poly(ethylene glycol) paste with in vivo effects against glioblastoma

Introduction

The median survival of patients with glioblastoma multiforme (astrocytoma grade 4) remains less than 18 months despite radical surgery, radiotherapy and systemic chemotherapy. Surgical implantation of chemotherapy eluting wafers into the resection cavity has been shown to improve length of survival but the current licensed therapy has several drawbacks. This paper investigates in vivo efficacy of a novel drug eluting paste in glioblastoma.

Methods

Poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) self-sintering paste was loaded with the chemotherapeutic agent etoposide and delivered surgically into partially resected tumours in a flank murine glioblastoma xenograft model.

Results

Surgical delivery of the paste was successful and practical, with no toxicity or surgical morbidity to the animals. The paste was retained in the tumour cavity, and preliminary results suggest a useful antitumour and antiangiogenic effect, particularly at higher doses. Bioluminescent imaging was not affected significantly by the presence of the paste in the tumour.

Conclusions

Chemotherapy loaded PLGA/PEG paste seems to be a promising technology capable of delivering active drugs into partially resected tumours. The preliminary results of this study suggest efficacy with no toxicity and will lead to larger scale efficacy studies in orthotopic glioblastoma models.     

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.     

Global Analysis Reveals the Complexity of the Human Glomerular Extracellular Matrix

The glomerulus contains unique cellular and extracellular matrix (ECM) components, which are required for intact barrier function. Studies of the cellular components have helped to build understanding of glomerular disease; however, the full composition and regulation of glomerular ECM remains poorly understood. We used mass spectrometry-based proteomics of enriched ECM extracts for a global analysis of human glomerular ECM in vivo and identified a tissue-specific proteome of 144 structural and regulatory ECM proteins. This catalog includes all previously identified glomerular components plus many new and abundant components. Relative protein quantification showed a dominance of collagen IV, collagen I, and laminin isoforms in the glomerular ECM together with abundant collagen VI and TINAGL1. Protein network analysis enabled the creation of a glomerular ECM interactome, which revealed a core of highly connected structural components. More than one half of the glomerular ECM proteome was validated using colocalization studies and data from the Human Protein Atlas. This study yields the greatest number of ECM proteins relative to previous investigations of whole glomerular extracts, highlighting the importance of sample enrichment. It also shows that the composition of glomerular ECM is far more complex than previously appreciated and suggests that many more ECM components may contribute to glomerular development and disease processes. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the dataset identifier PXD000456.The glomerulus is a sophisticated organelle comprising unique cellular and extracellular matrix (ECM) components. Fenestrated capillary endothelial cells and overlying podocytes are separated by a specialized glomerular basement membrane (GBM), and these three components together form the filtration barrier. Mesangial cells and their associated ECM, the mesangial matrix, exist between adjacent capillary loops and maintain the three-dimensional organization of the capillary bundle. In turn, the parietal epithelial cells and ECM of Bowman’s capsule enclose this network of capillaries. Cells adhere to ECM proteins by adhesion receptors, and these interactions are required to maintain intact barrier function of the glomerulus.^1,2In addition to operating as a signaling platform, ECM provides a structural scaffold for adjacent cells and has a tissue-specific molecular composition.^3,4 Candidate-based investigations of glomerular ECM have focused on the GBM and shown that it resembles the typical basal lamina found in multicellular organisms, containing a core of glycoproteins (collagen IV, laminins, and nidogens) and heparan sulfate proteoglycans (agrin, perlecan, and collagen XVIII).⁵ Mesangial and parietal cell ECMs have been less well investigated; nonetheless, they are also thought to contain similar core components in addition to other glycoproteins, including fibronectin.^6,7 Thus, the glomerulus consists of a combination of condensed ECM within the GBM and Bowman’s capsule and loose ECM supporting the mesangial cells.The ECM compartments in the glomerulus are thought to be distinct and exhibit different functional roles. The GBM is integral to the capillary wall and therefore, functionally linked to glomerular filtration.⁵ Mutations of tissue-restricted isoforms of collagen IV (COL4A3, COL4A4, and COL4A5) and laminin (LAMB2), which are found in the GBM, cause significant barrier dysfunction and ultimately, renal failure.^8,9 Less is understood about the functions of mesangial and parietal cell ECMs, although expansion of the mesangial compartment is a histologic pattern seen across the spectrum of glomerular disease.¹⁰Compositional investigation of the distinct glomerular ECM compartments is limited by the technical difficulties of separation. Early investigations of GBM constituents used the relative insolubility of ECM proteins to facilitate separation from cellular proteins in the glomerulus but did not separate the GBM from mesangial and parietal cells ECMs.^11,12 Recently, studies incorporating laser microdissection of glomerular sections have been coupled with proteomic analyses.^13,14 These studies report both cellular and ECM components and typically require pooled material from glomerular sections to improve protein identification. The ability of laser microdissection to separate glomerular ECM compartments has not yet been tested; however, this approach will be limited by the amount of protein that is possible to retrieve. To achieve good coverage of ECM proteins within a tissue, proteomic studies need to combine a reduction in sample complexity with maximal protein quantity. Currently, the inability to separate glomerular ECM compartments in sufficient quantity is a limitation that prohibits proteomic studies of these structures; however, for other tissues, proteomic analysis of ECM has been achieved by enrichment of ECM combined with sample fractionation.¹⁵Although the composition of the ECM in other tissues has been addressed using proteomic approaches,¹⁵ studies of glomerular ECM to date have used candidate-based technologies. These studies have identified key molecular changes during development and disease and highlighted the compositional and organizational dynamics of glomerular ECM. Nonetheless, the extracellular environment within the glomerulus is the setting for a complex series of interactions between both structural ECM proteins and ECM-associated proteins, such as growth factors^16–18 and proteases,¹⁹ which together provide a specialized niche to support glomerular cell function. Therefore, to interrogate this complexity effectively, a systems-level understanding of glomerular ECM is required. To address the need for a global analysis of the extracellular environment within the glomerulus, we used mass spectrometry (MS)-based proteomics of glomerular ECM fractions to define the human glomerular ECM proteome.