Leptin Signaling Protects NK Cells from Apoptosis During Development in Mouse Bone Marrow

Increasing evidence indicates a role of leptin in immune response, but it remains largely unclear whether leptin signaling is involved in regulating NK cell development in the bone marrow （BM）. In this study, we have characterized NK cell differentiation and maturation in the BM of leptin-receptor deficient db/db mice at a prediabetic stage. Although the BM cellularity was similar to the control value, the total number of NK cells was severely reduced in mutant mice. Flow cytometric analysis of db/db BM cells revealed significantly decreased frequencies of developing NK cells at various stages of differentiation. BM db/db NK cells displayed markedly increased apoptosis but maintained normal cell cycling status and proliferative capacity. Moreover, recombinant leptin could significantly enhance the survival of NK cells from wild-type mice in cultures. Further examination on NK cell functional activity showed that db/db NK cells exhibited normal intrinsic cytotoxicity with significantly increased IL-10 production. Taken together, our findings suggest that leptin signaling regulates NK cell development via enhancing the survival of immature NK cells in mouse BM.     

Biological performance of a polycaprolactone-based scaffold used as fusion cage device in a large animal model of spinal reconstructive surgery

A bioactive and bioresorbable scaffold fabricated from medical grade poly (epsilon-caprolactone) and incorporating 20% beta-tricalcium phosphate (mPCL–TCP) was recently developed for bone regeneration at load bearing sites. In the present study, we aimed to evaluate bone ingrowth into mPCL–TCP in a large animal model of lumbar interbody fusion. Six pigs underwent a 2-level (L3/4; L5/6) anterior lumbar interbody fusion (ALIF) implanted with mPCL–TCP + 0.6 mg rhBMP-2 as treatment group while four other pigs implanted with autogenous bone graft served as control. Computed tomographic scanning and histology revealed complete defect bridging in all (100%) specimen from the treatment group as early as 3 months. Histological evidence of continuing bone remodeling and maturation was observed at 6 months. In the control group, only partial bridging was observed at 3 months and only 50% of segments in this group showed complete defect bridging at 6 months. Furthermore, 25% of segments in the control group showed evidence of graft fracture, resorption and pseudoarthrosis. In contrast, no evidence of graft fractures, pseudoarthrosis or foreign body reaction was observed in the treatment group. These results reveal that mPCL–TCP scaffolds could act as bone graft substitutes by providing a suitable environment for bone regeneration in a dynamic load bearing setting such as in a porcine model of interbody spine fusion.     

Microfeature guided skeletal muscle tissue engineering for highly organized 3-dimensional free-standing constructs

Engineering tissue similar in structure to their natural equivalents is a major challenge and crucial to function. Despite attempts to engineer skeletal muscle, it is still difficult to effectively mimic tissue architecture. Rigid scaffolds can guide cell alignment but have the critical drawback of hindering mechanical function of the resultant tissue. We present a method for creating highly ordered tissue-only constructs by using rigid microtopographically patterned surfaces to first guide myoblast alignment, followed by transfer of aligned myotubes into a degradable hydrogel and self-organization of the ordered cells into a functional, 3-dimensional, free-standing construct independent of the initial template substrate. Histology revealed an intracellular organization resembling that of native muscle. Aligned cell constructs exhibited a 2-fold increase in peak force production compared to controls. Effective specific force, or force normalized over cross-sectional area, was increased by 23%. This template, transfer, and self-organization strategy is envisioned to be broadly useful in improving construct function and clinical applicability for highly ordered tissues like muscle.     

Roles of Neutrophil Gelatinase-Associated Lipocalin in Continuous Ambulatory Peritoneal Dialysis-Related Peritonitis

Introduction  We measured the neutrophil gelatinase-associated lipocalin (NGAL) concentration in peritoneal dialysate effluent (PDE) collected following an acute episode of continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis. Results  NGAL concentration in PDE increased in the first 3 days after developing peritonitis and correlated well with the neutrophil count. In patients with culture-negative peritonitis, the NGAL in PDE was lower than that in patients with gram-positive or gram-negative peritonitis. Apart from providing additional diagnostic support to bacterial-induced peritonitis, measurement of NGAL in PDE may be useful to differentiate the neutrophil-dependent culture-negative peritonitis from that associated with non-bacterial or non-cellular etiologies. Conclusion  Human peritoneal mesothelial cell (HPMC) is another source of NGAL during peritonitis. NGAL was specifically induced in HPMC by IL-1β. Incubation of HPMC with recombinant NGAL reversed the transforming growth factor-β-induced up-regulation of Snail and vimentin but rescued the down-regulation of E-cadherin. Our data suggest that NGAL may exert a protective effect in modulating the epithelial-to-mesenchymal transition activated following peritonitis.     

Cervical spine instability following cervical laminectomies for Chiari II malformation: a retrospective cohort study

Objective  The treatment of symptomatic Chiari II malformations typically involves multilevel cervical laminectomies in very young children. These patients are at significant risk of cervical instability. The purpose of this study was to determine the incidence and significance of cervical instability after multilevel cervical laminectomies in a cohort of patients decompressed for Chiari II malformation. Methods  Postoperative dynamic lateral cervical spine radiographs were obtained on pediatric patients who had multilevel cervical laminectomies for symptomatic Chiari II malformations. Postoperative cervical spine instability was determined radiographically using published criteria. Clinical instability and need for cervical fusion were also assessed. Results  Nine patients met inclusion criteria for the study. Five of the nine patients (56%) showed evidence of radiographic instability of their cervical spines following surgery for their Chiari II malformations, according to the criteria used. No patient showed evidence of clinical instability or required cervical fusion. Conclusion  Radiographic evidence of cervical spine instability following multilevel cervical laminectomies for Chiari II is common but may be of minimal clinical significance. The reason for the lack of clinical instability in what might be considered high-risk patients is not understood.     

The dynamic process of adherence to a renal therapeutic regimen: Perspectives of patients undergoing continuous ambulatory peritoneal dialysis

Background

The nature of end-stage renal disease and the need for continuous ambulatory peritoneal dialysis require patients to manage various aspects of the disease, its symptoms and treatment. After attending a training programme, patients are expected to adhere to the renal therapeutic regimen and manage their disease with the knowledge and skills learned. While patients are the stakeholders of their health and related behaviour, their perceptions of adherence and how they adhere to their renal therapeutic regimen remains unexplored.

Aims

To understand adherence from patients’ perspectives and to describe changes in adherence to a therapeutic regimen among patients undergoing continuous ambulatory peritoneal dialysis.

Design

This study used a mixed methods design with two phases – a survey in phase I and semi-structured interviews in phase II. This paper presents phase II of the study.

Settings

The study was conducted at a renal unit of an acute hospital in Hong Kong.

Participants

Based on the phase I survey results, maximum variation sampling was employed to purposively recruit 36 participants of different genders (18 males, 18 females), ages (35–76 years), and lengths of dialysis experience (11–103 months) for the phase II interviews.

Methods

Data were collected by tape-recorded semi-structured interviews. Content analysis was employed to analyse the transcribed data. Data collection and analysis were conducted simultaneously.

Findings

Adherence was a dynamic process with three stages. At the stage of initial adherence, participants attempted to follow instructions but found that strict persistent adherence was impossible. After the first 2–6 months of dialysis, participants entered the stage of subsequent adherence, when they adopted selective adherence through experimenting, monitoring and making continuous adjustments. The stage of long-term adherence commenced after 3–5 years of dialysis, when participants were able to assimilate the modified therapeutic regimen into everyday life.

Conclusions

The process of adherence was dynamic as there were fluctuations at each stage of the participants’ adherence. With reference to each stage identified, nursing interventions can be developed to help patients achieve smooth transition throughout all the stages.     

Volumetric and Functional Recovery of the Remnant Liver After Major Liver Resection with Prior Portal Vein Embolization

Introduction  Portal vein embolization is an accepted method to increase the future remnant liver preoperatively. The aim of this study was to assess the effect of preoperative portal vein embolization on liver volume and function 3 months after major liver resection. Materials and methods  This is a retrospective case-control study. Data were collected of patients who underwent portal vein embolization prior to (extended) right hemihepatectomy and of control patients who underwent the same type of resection without prior portal vein embolization. Liver volumes were measured by computed tomography volumetry before portal vein embolization, before liver resection, and 3 months after liver resection. Liver function was assessed by hepatobiliary scintigraphy before and 3 months after liver resection. Results  Ten patients were included in the embolization group and 13 in the control group. Groups were comparable for gender, age, and number of patients with a compromised liver. The mean future remnant liver volume was 33.0 ± 8.0% prior to portal vein embolization in the embolization group and 45.6 ± 9.1% in the control group (p < 0.01). Prior to surgery, there were no significant differences in future remnant liver volume and function between the groups. Three months postoperatively, the mean remnant liver volume was 81.9 ± 8.9% of the initial total liver volume in the embolization group and 79.4 ± 11.0% in the control group (p > 0.05). Remnant liver function increased up to 88.1 ± 17.4% and 83.3 ± 14% respectively of the original total liver function (p > 0.05). Conclusion  Preoperative portal vein embolization does not negatively influence postoperative liver regeneration assessed 3 months after major liver resection. No grant support. Paper presented at the SSAT, Chicago, June 1, 2009.     

Disposable platform provides visual and color-based point-of-care anemia self-testing

BACKGROUND. Anemia, or low blood hemoglobin (Hgb) levels, afflicts 2 billion people worldwide. Currently, Hgb levels are typically measured from blood samples using hematology analyzers, which are housed in hospitals, clinics, or commercial laboratories and require skilled technicians to operate. A reliable, inexpensive point-of-care (POC) Hgb test would enable cost-effective anemia screening and chronically anemic patients to self-monitor their disease. We present a rapid, stand-alone, and disposable POC anemia test that, via a single drop of blood, outputs color-based visual results that correlate with Hgb levels.METHODS. We tested blood from 238 pediatric and adult patients with anemia of varying degrees and etiologies and compared hematology analyzer Hgb levels with POC Hgb levels, which were estimated via visual interpretation using a color scale and an optional smartphone app for automated analysis.RESULTS. POC Hgb levels correlated with hematology analyzer Hgb levels (r = 0.864 and r = 0.856 for visual interpretation and smartphone app, respectively), and both POC test methods yielded comparable sensitivity and specificity for detecting any anemia (n = 178) (<11 g/dl) (sensitivity: 90.2% and 91.1%, specificity: 83.7% and 79.2%, respectively) and severe anemia (n = 10) (<7 g/dl) (sensitivity: 90.0% and 100%, specificity: 94.6% and 93.9%, respectively).CONCLUSIONS. These results demonstrate the feasibility of this POC color-based diagnostic test for self-screening/self-monitoring of anemia.TRIAL REGISTRATION. Not applicable.FUNDING. This work was funded by the FDA-funded Atlantic Pediatric Device Consortium, the Georgia Research Alliance, Children’s Healthcare of Atlanta, the Georgia Center of Innovation for Manufacturing, and the InVenture Prize and Ideas to Serve competitions at the Georgia Institute of Technology.     

Skin Electroporation of a Plasmid Encoding hCAP-18/LL-37 Host Defense Peptide Promotes Wound Healing

Host defense peptides, in particular LL-37, are emerging as potential therapeutics for promoting wound healing and inhibiting bacterial growth. However, effective delivery of the LL-37 peptide remains limiting. We hypothesized that skin-targeted electroporation of a plasmid encoding hCAP-18/LL-37 would promote the healing of wounds. The plasmid was efficiently delivered to full-thickness skin wounds by electroporation and it induced expression of LL-37 in the epithelium. It significantly accelerated reepithelialization of nondiabetic and diabetic wounds and caused a significant VEGFa and interleukin (IL)-6 induction. IL-6 was involved in LL-37–mediated keratinocyte migration in vitro and IL-6 neutralizing antibodies delivered to mice were able to suppress the wound healing activity of the hCAP-18/LL-37 plasmid. In a hindlimb ischemia model, electroporation of the hCAP-18/LL-37 plasmid increased blood perfusion, reduced muscular atrophy, and upregulated the angiogenic chemokines VEGFa and SDF-1a, and their receptors VEGF-R and CXCR-4. These findings demonstrate that a localized gene therapy with LL-37 is a promising approach for the treatment of wounds.