Association of Elevated Perioperative Blood Glucose With Complications and Postoperative Outcomes Following Traumatic Spine Surgery.

BACKGROUND: Perioperative blood glucose control has been demonstrated to influence outcomes following spine surgery, though this association has not been fully elucidated in patients with traumatic spine injuries. This study sought to determine the association between perioperative blood glucose levels and complications or outcomes in patients undergoing spine surgery due to injury. METHODS: A retrospective review was conducted to identify patients who underwent spine surgery due to traumatic injuries between 1 March 2020 and 29 September 2022 at a single academic institution. Descriptive factors, complications, and outcomes were compared between those with a postoperative blood glucose level of <200 mg/dL and those with a preoperative glucose of <200 mg/dL. RESULTS: Patients with a post- and preoperative blood glucose of ≥200 mg/dL had significantly higher odds of respiratory complications (OR = 2.1, 2.1, P = 0.02, 0.03), skin/wound complications (OR = 2.2, 2.8, P = 0.04, 0.03), and increased hospital length of stay (OR = 9.6, 12.1, P = 0.02, 0.03) compared with those with blood glucose of <200 mg/dL. Those with postoperative glucose ≥200 mg/dL also had significantly higher odds of inpatient mortality (OR = 4.5, P = 0.04) when controlling for confounding factors. Neither pre- nor postoperative blood glucose of ≥200 mg/dL was associated with an improvement in American Spinal Injury Association Impairment Scale score at the final follow-up when controlling for multiple confounding factors (P = 0.44, 0.06). CONCLUSION: Elevated blood glucose both pre- and postoperatively was associated with an increased rate of postoperative complications and negative postoperative outcomes. However, there was no association between elevated blood glucose levels and neurological recovery following traumatic spinal injury.

Open Ankle Fractures in Older Individuals: A Multi-center Study.

The purpose of this study is to identify demographics, etiology, comorbidities, treatment, complications, and outcomes for older patients with open ankle fractures. Patients ≥60 years old who sustained an open ankle fracture between January 1, 2004 and March 31, 2014 at 6 Level 1 trauma centers were retrospectively reviewed. Univariate analysis using chi-squared or Student's t test was performed to identify associations between preoperative variables and 2 postoperative outcomes of interest: amputation and 1-year mortality. Multivariate analysis was performed using stepwise logistical regression to identify independent predictors of postoperative amputation and 1-year mortality. Of the 162 total patients, the most common mechanism of injury was a ground-level fall (51.9%). The most common fracture types were bimalleolar fractures (52.5%) followed by trimalleolar fractures (26.5%), with 41.5% of the fractures classified as Gustilo Anderson Classification Type 2 and 38.6% classified as Type 3A. The average number of surgeries required per patient was 2.1. Complications included: 15.4% superficial infection rate, 9.9% deep infection rate, and 9.3% amputation rate. The 1-year mortality rate was 13.6% and the overall mortality rate was 25.9%. Male gender and fracture type were found to be independent predictors for amputation after surgery (p = .009, .005, respectively). Older age and having diabetes were independent predictors for 1-year mortality after surgery (p = .021, .005 respectively). Overall, open ankle fractures in older individuals were associated with high rates of amputation and mortality.

A Retrospective Comparative Analysis on the Effect of Tranexamic Acid to Reduce Perioperative Blood Loss in Patients Undergoing Cervical Spine Surgery.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVE: The purpose of this study is to assess the impact of intravenous TXA on blood loss outcomes in anterior, posterior, and combined approaches for elective cervical spine surgery. SUMMARY OF BACKGROUND DATA: Tranexamic acid (TXA) has been shown to reduce blood loss in a variety of operations, such as lumbar spine surgery. However, limited studies have evaluated the efficacy of TXA in cervical spine surgery. METHODS: We performed a retrospective review of a single surgeon's elective cervical spine operations between September 2011 and March 2017. Patients were divided into 3 groups: anterior approach, posterior approach, or combined approach. Patients were then further subdivided into TXA versus control groups based on whether they received TXA treatment. We performed multiple linear regressions to assess the relationship between the use of TXA and other dependent variables (number of vertebral levels treated, need for a vertebral corpectomy) on total perioperative blood loss, intraoperative estimated blood loss, postoperative drain output, total operative time, postoperative change in hemoglobin, and occurrence of transfusion and/or postoperative deep venous thrombus (DVT). RESULTS: We found that the use of TXA statistically significantly reduced total perioperative blood loss ( P =0.04) and postoperative drain output ( P =0.004) in posterior surgical approach cervical spine surgery but did not statistically significantly impact any blood loss variables in anterior or combined surgical approaches to elective cervical spine surgery. The use of TXA was a significant predictor for a decrease in intraoperative ( P =0.02) and postoperative ( P <0.01) blood loss. CONCLUSIONS: This study found that TXA statistically significantly decreased total blood loss and postoperative drain output when controlling for multiple confounding factors. LEVEL OF EVIDENCE: Level III.

The Effects of Blood Glucose Control in the Operative Spine Patient: A Systematic Review.

OBJECTIVE: To our knowledge, this is the first systematic review to evaluate the available literature on the effects of perioperative serum glucose (SG) on outcomes for patients undergoing spine surgery. This review will add insight into how the perioperative management of SG affects the outcomes of patients undergoing spine surgery. METHODS: Three databases were used in this review including Embase, PubMed, and Cochrane Library. The searches were from 2012 to 2022 and included the terms "spine surgery" and "glucose level" to identify studies that demonstrated a correlation between glucose level and postoperative outcomes. Pediatric studies, those that did not specify spine surgical outcomes related to glucose levels, and non-English studies were excluded. The methodological items for nonrandomized studies score was used to assess risk of bias in the included studies. RESULTS: This review included a total of 9 cohort studies, both prospective and retrospective, encompassing a total of 431,156 subjects. Seven of the 9 studies reported an increased overall complication rate among patients with diabetes or with higher SG levels, and 4 studies demonstrated an increased infection rate among this population. Two studies reported an association between decreased SG levels and improved neurological recovery when a deficit was present preoperatively, and 1 of the studies found that this association was statistically significant. LIMITATIONS: Limitations of this review include lack of standardization regarding type of surgery, location of the spine, and level of evidence. CONCLUSION: Most of the current literature suggests that elevated SG levels in patients undergoing spine surgery likely leads to higher complication rates and may lead to increased infection rates, and this review reinforced the current evidence. Additionally, perioperative SG levels may be associated with the extent of neurological recovery after surgery, but further investigation may be warranted. CLINICAL RELEVANCE: This review adds to the current body of evidence regarding perioperative SG levels and its association with complications.

C-X-C Motif Chemokine Ligand 9 and Its CXCR3 Receptor Are the Salt and Pepper for T Cells Trafficking in a Mouse Model of Gaucher Disease.

Gaucher disease is a lysosomal storage disease, which happens due to mutations in GBA1/Gba1 that encodes the enzyme termed as lysosomal acid ß-glucosidase. The major function of this enzyme is to catalyze glucosylceramide (GC) into glucose and ceramide. The deficiency of this enzyme and resultant abnormal accumulation of GC cause altered function of several of the innate and adaptive immune cells. For example, augmented infiltration of T cells contributes to the increased production of pro-inflammatory cytokines, (e.g., IFNγ, TNFα, IL6, IL12p40, IL12p70, IL23, and IL17A/F). This leads to tissue damage in a genetic mouse model (Gba19V/-) of Gaucher disease. The cellular mechanism(s) by which increased tissue infiltration of T cells occurs in this disease is not fully understood. Here, we delineate role of the CXCR3 receptor and its exogenous C-X-C motif chemokine ligand 9 (CXCL9) in induction of increased tissue recruitment of CD4+ T and CD8+ T cells in Gaucher disease. Intracellular FACS staining of macrophages (Mϕs) and dendritic cells (DCs) from Gba19V/- mice showed elevated production of CXCL9. Purified CD4+ T cells and the CD8+ T cells from Gba19V/- mice showed increased expression of CXCR3. Ex vivo and in vivo chemotaxis experiments showed CXCL9 involvement in the recruitment of Gba19V/- T cells. Furthermore, antibody blockade of the CXCL9 receptor (CXCR3) on T cells caused marked reduction in CXCL9- mediated chemotaxis of T cells in Gba19V/- mice. These data implicate abnormalities of the CXCL9-CXCR3 axis leading to enhanced tissue recruitment of T cells in Gaucher disease. Such results provide a rationale for blockade of the CXCL9/CXCR3 axis as potential new therapeutic targets for the treatment of inflammation in Gaucher disease.

Resident Wellness During the COVID-19 Pandemic: A Nationwide Survey of Orthopaedic Residents.

INTRODUCTION: The COVID-19 pandemic has influenced the resident workforce to a particularly powerful and unexpected extent. Given the drastic changes to resident roles, expectations, and responsibilities, many valuable lessons regarding resident concerns and wellness can be garnered from this unique experience. METHODS: A voluntary survey was sent to 179 Accreditation Council for Graduate Medical Education-accredited orthopaedic surgery residency program directors to distribute to their residents. Questions focused on issues that may have occurred, program's responses, and expectations of programs during the pandemic. RESULTS: In total, 507 residents completed the survey, and 10% reported being deployed to do nonorthopaedic-related care, with junior classes being more likely to receive this assignment (P < 0.001). The greatest concern for respondents was the possibility of getting family members sick (mean = 3.89, on scale of 1-5), followed by personally contracting the illness (mean = 3.38). DISCUSSION: The COVID-19 pandemic has resulted in numerous changes and novel sources of adversity for the orthopaedic surgery resident. Contrary to popular opinion, most residents are comfortable with the proposition of providing nonorthopaedic care. The possibility of bringing a pathogen to the home environment and infecting family members seems to be an overarching concern, and efforts to ensure resident and family safety are key.

Systemic enzyme delivery by blood-brain barrier-penetrating SapC-DOPS nanovesicles for treatment of neuronopathic Gaucher disease.

BACKGROUND: Enzyme replacement therapy (ERT) can positively affect the visceral manifestations of lysosomal storage diseases (LSDs). However, the exclusion of the intravenous ERT agents from the central nervous system (CNS) prevents direct therapeutic effects. METHODS: Using a neuronopathic Gaucher disease (nGD) mouse model, CNS-ERT was created using a systemic, non-invasive, and CNS-selective delivery system based on nanovesicles of saposin C (SapC) and dioleoylphosphatidylserine (DOPS) to deliver to CNS cells and tissues the corrective, functional acid ß-glucosidase (GCase). FINDINGS: Compared to free GCase, human GCase formulated with SapC-DOPS nanovesicles (SapC-DOPS-GCase) was more stable in serum, taken up into cells, mostly by a mannose receptor-independent pathway, and resulted in higher activity in GCase-deficient cells. In contrast to free GCase, SapC-DOPS-GCase nanovesicles penetrated through the blood-brain barrier into the CNS. The CNS targeting was mediated by surface phosphatidylserine (PS) of blood vessel and brain cells. Increased GCase activity and reduced GCase substrate levels were found in the CNS of SapC-DOPS-GCase-treated nGD mice, which showed profound improvement in brain inflammation and neurological phenotypes. INTERPRETATION: This first-in-class CNS-ERT approach provides considerable promise of therapeutic benefits for neurodegenerative diseases. FUNDING: This study was supported by the National Institutes of Health grants R21NS 095047 to XQ and YS, R01NS 086134 and UH2NS092981 in part to YS; Cincinnati Children's Hospital Medical Center Research Innovation/Pilot award to YS and XQ; Gardner Neuroscience Institute/Neurobiology Research Center Pilot award to XQ and YS, Hematology-Oncology Programmatic Support from University of Cincinnati and New Drug State Key Project grant 009ZX09102-205 to XQ.

Keloid and Hypertrophic Scar Formation, Prevention, and Management: Standard Review of Abnormal Scarring in Orthopaedic Surgery.

Keloid and hypertrophic scar formation after orthopaedic surgical closure is a complex issue. The nature and location of procedures maximize wound tension, leave foreign bodies, and diminish dermal supply, all potentiating keloid formation. There is little discussion regarding the pathophysiology and management of this recurrent problem in orthopaedic literature. Keloid formation is a fibroproliferative disorder resulting in extensive production of extracellular matrix and collagen, but prevention and treatment is poorly understood. Patient and surgical factors contributing to the development of this condition are discussed. The treatments include both medical and surgical therapies that work at a biologic level and attempt to produce a cosmetic and complication-free management strategy. Medical options that have been investigated include combinations of intralesional steroid therapy, laser therapy, and biologics. Preventive surgical closure and excision remain mainstays of treatment. Radiation therapy has also been used in refractory cases with mixed results. Despite medical therapies and surgical excision aimed at treating the resulting scar, recurrence rate is very high for all modalities that have been studied to this point. Future work is being done to better understand the pathophysiology leading to keloid and hypertrophic scar formation in an effort to find preventive methods as compared to treatment strategies.

Epidural Abscess Caused by Gas-Producing Clostridium Septicum: A Case Report.

CASE: Few cases have reported Clostridium species of bacteria as a source for vertebral osteomyelitis and epidural abscesses. The subspecies of Clostridium septicum has not been described as a cause. This case describes a 69-year-old man who hematogenously spread C. septicum without associated malignancy, subsequently failed conservative management in the form of intravenous antibiotics, and was definitively treated with surgical intervention through a minimally invasive approach. CONCLUSIONS: An epidural abscess occurring in a surgically naive patient is a rare phenomenon. An epidural abscess caused by C. septicum is even rarer. Appropriate imaging, early recognition, and surgical debridement can lead to a favorable outcome.

Intravenous infusion of iPSC-derived neural precursor cells increases acid ß-glucosidase function in the brain and lessens the neuronopathic phenotype in a mouse model of Gaucher disease.

Gaucher disease (GD) is caused by GBA1 mutations leading to functional deficiency of acid-ß-glucosidase (GCase). No effective treatment is available for neuronopathic GD (nGD). A subclass of neural stem and precursor cells (NPCs) expresses VLA4 (integrin α4ß1, very late antigen-4) that facilitates NPC entry into the brain following intravenous (IV) infusion. Here, the therapeutic potential of IV VLA4+NPCs was assessed for nGD using wild-type mouse green fluorescent protein (GFP)-positive multipotent induced pluripotent stem cell (iPSC)-derived VLA4+NPCs. VLA4+NPCs successfully engrafted in the nGD (4L;C*) mouse brain. GFP-positive cells differentiated into neurons, astrocytes and oligodendrocytes in the brainstem, midbrain and thalamus of the transplanted mice and significantly improved sensorimotor function and prolonged life span compared to vehicle-treated 4L;C* mice. VLA4+NPC transplantation significantly decreased levels of CD68 and glial fibrillary acidic protein, as well as TNFα mRNA levels in the brain, indicating reduced neuroinflammation. Furthermore, decreased Fluoro-Jade C and NeuroSilver staining suggested inhibition of neurodegeneration. VLA4+NPC-engrafted 4L;C* midbrains showed 35% increased GCase activity, reduced substrate [glucosylceramide (GC, -34%) and glucosylsphingosine (GS, -11%)] levels and improved mitochondrial oxygen consumption rates in comparison to vehicle-4L;C* mice. VLA4+NPC engraftment in 4L;C* brain also led to enhanced expression of neurotrophic factors that have roles in neuronal survival and the promotion of neurogenesis. This study provides evidence that iPSC-derived NPC transplantation has efficacy in an nGD mouse model and provides proof of concept for autologous NPC therapy in nGD.

Extracellular Lipids Accumulate in Human Carotid Arteries as Distinct Three-Dimensional Structures and Have Proinflammatory Properties.

Lipid accumulation is a key characteristic of advancing atherosclerotic lesions. Herein, we analyzed the ultrastructure of the accumulated lipids in endarterectomized human carotid atherosclerotic plaques using three-dimensional (3D) electron microscopy, a method never used in this context before. 3D electron microscopy revealed intracellular lipid droplets and extracellular lipoprotein particles. Most of the particles were aggregated, and some connected to needle-shaped or sheet-like cholesterol crystals. Proteomic analysis of isolated extracellular lipoprotein particles revealed that apolipoprotein B is their main protein component, indicating their origin from low-density lipoprotein, intermediate-density lipoprotein, very-low-density lipoprotein, lipoprotein (a), or chylomicron remnants. The particles also contained small exchangeable apolipoproteins, complement components, and immunoglobulins. Lipidomic analysis revealed differences between plasma lipoproteins and the particles, thereby indicating involvement of lipolytic enzymes in their generation. Incubation of human monocyte-derived macrophages with the isolated extracellular lipoprotein particles or with plasma lipoproteins that had been lipolytically modified in vitro induced intracellular lipid accumulation and triggered inflammasome activation in them. Taken together, extracellular lipids accumulate in human carotid plaques as distinct 3D structures that include aggregated and fused lipoprotein particles and cholesterol crystals. The particles originate from plasma lipoproteins, show signs of lipolytic modifications, and associate with cholesterol crystals. By inducing intracellular cholesterol accumulation (ie, foam cell formation) and inflammasome activation, the extracellular lipoprotein particles may actively enhance atherogenesis.

Trends in the Treatment of Single and Multilevel Cervical Stenosis: A Review of the American Board of Orthopaedic Surgery Database.

BACKGROUND: In order to identify any changes in the utilization of new and old techniques, we investigated trends in the operative management of cervical stenosis by orthopaedic surgeons applying for board certification. METHODS: We queried the American Board of Orthopaedic Surgery database from 1998 to 2013 to identify all of the cervical spine procedures for stenosis that had been performed by candidates taking Part II of the licensing examination. Longitudinal trends were determined for the utilized approach, the individual procedures that had been performed, and whether a motion-preserving technique had been employed. RESULTS: There were 5,068 cervical spine procedures performed by 1,025 candidates. Procedure totals remained relatively constant until 2011, when a sudden increase of 280% (202 to 768 procedures) was noted. This trend continued, reaching a 460% increase (202 to 1,131 procedures) compared with 2010. The number of candidates only rose by 150% (42 to 105) over the entire study period. The proportion of procedures performed via an anterior approach saw a bimodal distribution; early on, this approach predominated over posterior procedures and was largely driven by the number of corpectomies that were performed. From 2004 to 2011, posterior procedures became more prevalent, but there was a sharp decline in 2011, driven by the large number of anterior cervical discectomies and fusions that were performed. This remained constant through 2013. Lastly, motion-preserving techniques, which included total disc replacement and laminoplasty, had modest increases in utilization from 2005 to 2007. This increased prevalence was short-lived, and it steadily declined through 2014 to <5% utilization. CONCLUSIONS: The number of candidates performing cervical spine procedures increased more than twofold over a 16-year period. This reflects a larger proportion of the orthopaedic graduates who subspecialize in spine surgery. While the number of surgeons performing spine surgery has increased, the sheer number of procedures that each surgeon performed greatly outpaced the increased number of surgeons. Motion-preserving techniques had their peak utilization in 2007, and have since decreased to <5%, in contrast to fusion techniques, which predominate, comprising >90% of the performed procedures.

HIV in Orthopaedic Surgery.

The emergence of HIV in the United States has had important implications in the surgical setting. This blood-borne pathogen poses risks to both the surgeon and the patient undergoing an orthopaedic procedure. Although there has been research regarding the likelihood of orthopaedic surgeons contracting HIV during a surgical procedure, the correlation of HIV with postoperative prognosis has not been extensively examined. Because HIV-positive patients may be immunodeficient, they are at increased risk for certain postoperative complications, especially infection. Orthopaedic surgeons should have a thorough understanding of the effects of this disease on patients to optimize preoperative decision making, intraoperative care, and postoperative recovery.

Complement drives glucosylceramide accumulation and tissue inflammation in Gaucher disease.

Gaucher disease is caused by mutations in GBA1, which encodes the lysosomal enzyme glucocerebrosidase (GCase). GBA1 mutations drive extensive accumulation of glucosylceramide (GC) in multiple innate and adaptive immune cells in the spleen, liver, lung and bone marrow, often leading to chronic inflammation. The mechanisms that connect excess GC to tissue inflammation remain unknown. Here we show that activation of complement C5a and C5a receptor 1 (C5aR1) controls GC accumulation and the inflammatory response in experimental and clinical Gaucher disease. Marked local and systemic complement activation occurred in GCase-deficient mice or after pharmacological inhibition of GCase and was associated with GC storage, tissue inflammation and proinflammatory cytokine production. Whereas all GCase-inhibited mice died within 4-5 weeks, mice deficient in both GCase and C5aR1, and wild-type mice in which GCase and C5aR were pharmacologically inhibited, were protected from these adverse effects and consequently survived. In mice and humans, GCase deficiency was associated with strong formation of complement-activating GC-specific IgG autoantibodies, leading to complement activation and C5a generation. Subsequent C5aR1 activation controlled UDP-glucose ceramide glucosyltransferase production, thereby tipping the balance between GC formation and degradation. Thus, extensive GC storage induces complement-activating IgG autoantibodies that drive a pathway of C5a generation and C5aR1 activation that fuels a cycle of cellular GC accumulation, innate and adaptive immune cell recruitment and activation in Gaucher disease. As enzyme replacement and substrate reduction therapies are expensive and still associated with inflammation, increased risk of cancer and Parkinson disease, targeting C5aR1 may serve as a treatment option for patients with Gaucher disease and, possibly, other lysosomal storage diseases.

Lysosomal acid lipase deficiency: Expanding differential diagnosis.

The differential diagnoses for metabolic liver diseases may be challenging in clinical settings, which represents a critical issue for disorders such as lysosomal acid lipase deficiency (LAL-D). LAL-D is caused by deficient activity of the LAL enzyme, resulting in the accumulation of cholesteryl esters and triglycerides throughout the body, predominately in the liver, spleen, gastrointestinal tract, and blood vessel walls. LAL-D is a progressive, multi-organ disease with early mortality and significant morbidity characterized by a combination of hepatic dysfunction and dyslipidemia. Evidence suggests LAL-D may be substantially underdiagnosed or misdiagnosed, which is critical given that disease progression can be unpredictable, with liver failure and/or accelerated atherosclerosis potentially contributing to early mortality. However, given the development of a simple diagnostic test and recently approved treatment, LAL-D should be incorporated into the differential diagnosis in relevant clinical settings. LAL-D can be diagnosed using an LAL enzyme-based biochemical test, thereby allowing for active monitoring of patients to detect potential disease complications and consider treatment options including diet, lipid-lowering medication, and treatment with sebelipase alfa, a recombinant enzyme replacement therapy shown to provide clinical benefit and improve disease-relevant markers in clinical trials. To illustrate the complexity of diagnosing LAL-D, this manuscript will describe the path to diagnosing LAL-D in a series of patient cases in which LAL-D was diagnosed as well as in patients where other diseases, such as Gaucher disease and Niemann-Pick disease, were initially suspected.

Activation of p38 Mitogen-Activated Protein Kinase in Gaucher's Disease.

Gaucher's disease is caused by defects in acid ß-glucosidase 1 (GBA1) and has been also proposed as an inflammatory disease. GBA1 cleaves glucosylceramide to form ceramide, an established bioactive lipid, and defects in GBA1 lead to aberrant accumulation in glucosylceramide and insufficient formation of ceramide. We investigated if the pro-inflammatory kinase p38 is activated in Gaucher's disease, since ceramide has been proposed to suppress p38 activation. Three Gaucher's disease mouse models were employed, and p38 was found to be activated in lung and liver tissues of all Gaucher's disease mice. Most interestingly, neuronopathic Gaucher's disease type mice, but not non-neuronopathic ones, displayed significant activation of p38 and up-regulation of p38-inducible proinflammatory cytokines in brain tissues. In addition, all type of Gaucher's disease mice also showed increases in serum IL-6. As cellular signalling is believed to represent an in vivo inflammatory phenotype in Gaucher's disease, activation of p38 and possibly its-associated formation of proinflammatory cytokines were assessed in fibroblasts established from neuronopathic Gaucher's disease mice. In mouse Gaucher's disease cells, p38 activation and IL-6 formation by TNF-α treatment were enhanced as compared to those of wild type. Furthermore, human fibroblasts from Gaucher's disease patients also displayed increases in p38 activation and IL-6 formation as comparison to healthy counterpart. These results raise the potential that proinflammatory responses such as p38 activation and IL-6 formation are augmented in Gaucher's disease.

CNS, lung, and lymph node involvement in Gaucher disease type 3 after 11 years of therapy: clinical, histopathologic, and biochemical findings.

A Caucasian male with Gaucher disease type 3, treated with continuous enzyme therapy (ET) for 11 years, experienced progressive mesenteric and retroperitoneal lymphadenopathy, lung disease, and neurological involvement leading to death at an age of 12.5 years. Autopsy showed significant pathology of the brain, lymph nodes, and lungs. Liver and spleen glucosylceramide (GluCer) and glucosylsphingosine (GluS) levels were nearly normal and storage cells were cleared. Clusters of macrophages and very elevated GluCer and GluS levels were in the lungs, and brain parenchymal and perivascular regions. Compared to normal brain GluCer (GC 18:0), GluCer species with long fatty acid acyl chains were increased in the patient's brain. This profile was similar to that in the patient's lungs, suggesting that these lipids were present in brain perivascular macrophages. In the patient's brain, generalized astrogliosis, and enhanced LC3, ubiquitin, and Tau signals were identified in the regions surrounding macrophage clusters, indicating proinflammation, altered autophagy, and neurodegeneration. These findings highlight the altered phenotypes resulting from increased longevity due to ET, as well as those in poorly accessible compartments of brain and lung, which manifested progressive disease involvement despite ET.

An in vivo model of human small intestine using pluripotent stem cells.

Differentiation of human pluripotent stem cells (hPSCs) into organ-specific subtypes offers an exciting avenue for the study of embryonic development and disease processes, for pharmacologic studies and as a potential resource for therapeutic transplant. To date, limited in vivo models exist for human intestine, all of which are dependent upon primary epithelial cultures or digested tissue from surgical biopsies that include mesenchymal cells transplanted on biodegradable scaffolds. Here, we generated human intestinal organoids (HIOs) produced in vitro from human embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) that can engraft in vivo. These HIOs form mature human intestinal epithelium with intestinal stem cells contributing to the crypt-villus architecture and a laminated human mesenchyme, both supported by mouse vasculature ingrowth. In vivo transplantation resulted in marked expansion and maturation of the epithelium and mesenchyme, as demonstrated by differentiated intestinal cell lineages (enterocytes, goblet cells, Paneth cells, tuft cells and enteroendocrine cells), presence of functional brush-border enzymes (lactase, sucrase-isomaltase and dipeptidyl peptidase 4) and visible subepithelial and smooth muscle layers when compared with HIOs in vitro. Transplanted intestinal tissues demonstrated digestive functions as shown by permeability and peptide uptake studies. Furthermore, transplanted HIO-derived tissue was responsive to systemic signals from the host mouse following ileocecal resection, suggesting a role for circulating factors in the intestinal adaptive response. This model of the human small intestine may pave the way for studies of intestinal physiology, disease and translational studies.

The LIMP-2/SCARB2 binding motif on acid ß-glucosidase: basic and applied implications for Gaucher disease and associated neurodegenerative diseases.

The acid ß-glucosidase (glucocerbrosidase (GCase)) binding sequence to LIMP-2 (lysosomal integral membrane protein 2), the receptor for intracellular GCase trafficking to the lysosome, has been identified. Heterologous expression of deletion constructs, the available GCase crystal structures, and binding and co-localization of identified peptides or mutant GCases were used to identify and characterize a highly conserved 11-amino acid sequence, DSPIIVDITKD, within human GCase. The binding to LIMP-2 is not dependent upon a single amino acid, but the interactions of GCase with LIMP-2 are heavily influenced by Asp(399) and the di-isoleucines, Ile(402) and Ile(403). A single alanine substitution at any of these decreases GCase binding to LIMP-2 and alters its pH-dependent binding as well as diminishing the trafficking of GCase to the lysosome and significantly increasing GCase secretion. Enterovirus 71 also binds to LIMP-2 (also known as SCARB2) on the external surface of the plasma membrane. However, the LIMP-2/SCARB2 binding sequences for enterovirus 71 and GCase are not similar, indicating that LIMP-2/SCARB2 may have multiple or overlapping binding sites with differing specificities. These findings have therapeutic implications for the production of GCase and the distribution of this enzyme that is delivered to various organs.