Mechanisms contributing to inhibition of retinal ganglion cell death by cell permeable peptain-1 under glaucomatous stress.

This study assesses the neuroprotective potential of CPP-P1, a conjugate of an anti-apoptotic peptain-1 (P1) and a cell-penetrating peptide (CPP) in in vitro, in vivo, and ex vivo glaucoma models. Primary retinal ganglion cells (RGCs) were subjected to either neurotrophic factor (NF) deprivation for 48 h or endothelin-3 (ET-3) treatment for 24 h and received either CPP-P1 or vehicle. RGC survival was analyzed using a Live/Dead assay. Axotomized human retinal explants were treated with CPP-P1 or vehicle for seven days, stained with RGC marker RBPMS, and RGC survival was analyzed. Brown Norway (BN) rats with elevated intraocular pressure (IOP) received weekly intravitreal injections of CPP-P1 or vehicle for six weeks. RGC function was evaluated using a pattern electroretinogram (PERG). RGC and axonal damage were also assessed. RGCs from ocular hypertensive rats treated with CPP-P1 or vehicle for seven days were isolated for transcriptomic analysis. RGCs subjected to 48 h of NF deprivation were used for qPCR target confirmation. NF deprivation led to a significant loss of RGCs, which was markedly reduced by CPP-P1 treatment. CPP-P1 also decreased ET-3-mediated RGC death. In ex vivo human retinal explants, CPP-P1 decreased RGC loss. IOP elevation resulted in significant RGC loss in mid-peripheral and peripheral retinas compared to that in naive rats, which was significantly reduced by CPP-P1 treatment. PERG amplitude decline in IOP-elevated rats was mitigated by CPP-P1 treatment. Following IOP elevation in BN rats, the transcriptomic analysis showed over 6,000 differentially expressed genes in the CPP-P1 group compared to the vehicle-treated group. Upregulated pathways included CREB signaling and synaptogenesis. A significant increase in Creb1 mRNA and elevated phosphorylated Creb were observed in CPP-P1-treated RGCs. Our study showed that CPP-P1 is neuroprotective through CREB signaling enhancement in several settings that mimic glaucomatous conditions. The findings from this study are significant as they address the pressing need for the development of efficacious therapeutic strategies to maintain RGC viability and functionality associated with glaucoma.

Brain-derived neuerotrophic factor and related mechanisms that mediate and influence progesterone-induced neuroprotection.

Historically, progesterone has been studied significantly within the context of reproductive biology. However, there is now an abundance of evidence for its role in regions of the central nervous system (CNS) associated with such non-reproductive functions that include cognition and affect. Here, we describe mechanisms of progesterone action that support its brain-protective effects, and focus particularly on the role of neurotrophins (such as brain-derived neurotrophic factor, BDNF), the receptors that are critical for their regulation, and the role of certain microRNA in influencing the brain-protective effects of progesterone. In addition, we describe evidence to support the particular importance of glia in mediating the neuroprotective effects of progesterone. Through this review of these mechanisms and our own prior published work, we offer insight into why the effects of a progestin on brain protection may be dependent on the type of progestin (e.g., progesterone versus the synthetic, medroxyprogesterone acetate) used, and age, and as such, we offer insight into the future clinical implication of progesterone treatment for such disorders that include Alzheimer's disease, stroke, and traumatic brain injury.

The glycoimmune checkpoint receptor Siglec-7 interacts with T-cell ligands and regulates T-cell activation.

Siglec-7 (sialic acid-binding immunoglobulin-like lectin 7) is a glycan-binding immune receptor that is emerging as a significant target of interest for cancer immunotherapy. The physiological ligands that bind Siglec-7, however, remain incompletely defined. In this study, we characterized the expression of Siglec-7 ligands on peripheral immune cell subsets and assessed whether Siglec-7 functionally regulates interactions between immune cells. We found that disialyl core 1 O-glycans are the major immune ligands for Siglec-7 and that these ligands are particularly highly expressed on naïve T-cells. Densely glycosylated sialomucins are the primary carriers of these glycans, in particular a glycoform of the cell-surface marker CD43. Biosynthesis of Siglec-7-binding glycans is dynamically controlled on different immune cell subsets through a genetic circuit involving the glycosyltransferase GCNT1. Siglec-7 blockade was found to increase activation of both primary T-cells and antigen-presenting dendritic cells in vitro, indicating that Siglec-7 binds T-cell glycans to regulate intraimmune signaling. Finally, we present evidence that Siglec-7 directly activates signaling pathways in T-cells, suggesting a new biological function for this receptor. These studies conclusively demonstrate the existence of a novel Siglec-7-mediated signaling axis that physiologically regulates T-cell activity. Going forward, our findings have significant implications for the design and implementation of therapies targeting immunoregulatory Siglec receptors.

Estradiol and 3ß-diol protect female cortical astrocytes by regulating connexin 43 Gap Junctions.

While estrogens have been described to protect or preserve neuronal function in the face of insults such as oxidative stress, the prevailing mechanistic model would suggest that these steroids exert direct effects on the neurons. However, there is growing evidence that glial cells, such as astrocytes, are key cellular mediators of protection. Noting that connexin 43 (Cx43), a protein highly expressed in astrocytes, plays a key role in mediating inter-cellular communication, we hypothesized that Cx43 is a target of estradiol (E2), and the estrogenic metabolite of DHT, 3ß-diol. Additionally, we sought to determine if either or both of these hormones attenuate oxidative stress-induced cytotoxicity by eliciting a reduction in Cx43 expression or inhibition of Cx43 channel permeability. Using primary cortical astrocytes, we found that E2 and 3ß-diol were each protective against the mixed metabolic/oxidative insult, iodoacetic acid (IAA). Moreover, these effects were blocked by estrogen receptor antagonists. However, E2 and 3ß-diol did not alter Cx43 mRNA levels in astrocytes but did inhibit IAA-induced Cx43 gap junction opening/permeability. Taken together, these data implicate astrocyte Cx43 gap junction as an understudied mediator of the cytoprotective effects of estrogens in the brain. Given the wide breadth of disease states associated with Cx43 function/dysfunction, further understanding the relationship between gonadal steroids and Cx43 channels may contribute to a better understanding of the biological basis for sex differences in various diseases.

Identifying Genetic Regulators of Protein-Glycan Interactions with Genome-Wide CRISPR Screening.

Glycans are carbohydrate molecules appended to proteins and lipids on the surface of all living cells. Glycans play key roles in a wide array of biological processes, and structural changes in cell-surface glycosylation patterns have been connected to pathogenesis of several diseases. In particular, cancer cells frequently upregulate expression of glycans that bind to inhibitory receptors (lectins) on immune cells. These glycosylated antigens systematically inhibit immune activity and protect cancer cells from immune surveillance. Understanding how cancer cells generate these glycan ligands can thus lead to identification of novel druggable targets for therapeutic intervention. However, glycan ligand biosynthesis is subject to extremely complex genetic regulation, making it difficult to identify the key genes involved in production of immune-regulatory glycan antigens. In a recent publication, we described a CRISPR/Cas9 screening approach to identify genes that drive synthesis of ligands for glycan-binding immune receptors. Here, we outline a detailed, step-by-step protocol for completing this type of genome-wide screen. Our protocol produces a genome-wide atlas of all genes whose expression is required for cell-surface binding of a recombinant immune lectin. This dataset can be used both to identify novel ligands for immune lectins and annotate regulatory genes that drive changes in cancer-associated glycosylation. Our protocol serves as a general resource for researchers interested in the detailed study of cancer glyco-immunology. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Generation of a genome-wide CRISPR library using lentiviral transduction Support Protocol: Generation of dCas9KRAB-expressing K-562 cells Basic Protocol 2: Staining of genome-wide CRISPR libraries with Siglec-Fc reagents and fluorescence-activated cell sorting Basic Protocol 3: Library amplification and sequencing Basic Protocol 4: Data analysis and hit identification.

The endothelin receptor antagonist macitentan ameliorates endothelin-mediated vasoconstriction and promotes the survival of retinal ganglion cells in rats.

Glaucoma is a chronic and progressive eye disease, commonly associated with elevated intraocular pressure (IOP) and characterized by optic nerve degeneration, cupping of the optic disc, and loss of retinal ganglion cells (RGCs). The pathological changes in glaucoma are triggered by multiple mechanisms and both mechanical effects and vascular factors are thought to contribute to the etiology of glaucoma. Various studies have shown that endothelin-1 (ET-1), a vasoactive peptide, acting through its G protein coupled receptors, ETA and ETB, plays a pathophysiologic role in glaucoma. However, the mechanisms by which ET-1 contribute to neurodegeneration remain to be completely understood. Our laboratory and others demonstrated that macitentan (MAC), a pan endothelin receptor antagonist, has neuroprotective effects in rodent models of IOP elevation. The current study aimed to determine if oral administration of a dual endothelin antagonist, macitentan, could promote neuroprotection in an acute model of intravitreal administration of ET-1. We demonstrate that vasoconstriction following the intravitreal administration of ET-1 was attenuated by dietary administration of the ETA/ETB dual receptor antagonist, macitentan (5 mg/kg body weight) in retired breeder Brown Norway rats. ET-1 intravitreal injection produced a 40% loss of RGCs, which was significantly lower in macitentan-treated rats. We also evaluated the expression levels of glial fibrillary acidic protein (GFAP) at 24 h and 7 days post intravitreal administration of ET-1 in Brown Norway rats as well as following ET-1 treatment in cultured human optic nerve head astrocytes. We observed that at the 24 h time point the expression levels of GFAP was upregulated (indicative of glial activation) following intravitreal ET-1 administration in both retina and optic nerve head regions. However, following macitentan administration for 7 days after intravitreal ET-1 administration, we observed an upregulation of GFAP expression, compared to untreated rats injected intravitreally with ET-1 alone. Macitentan treatment in ET-1 administered rats showed protection of RGC somas but was not able to preserve axonal integrity and functionality. The endothelin receptor antagonist, macitentan, has neuroprotective effects in the retinas of Brown Norway rats acting through different mechanisms, including enhancement of RGC survival and reduction of ET-1 mediated vasoconstriction.

Prolonged Postoperative Opioid Use After Arthroscopic Femoroacetabular Impingement Syndrome Surgery: Predictors and Outcomes at Minimum 2-Year Follow-up.

BACKGROUND: The association between prolonged postoperative opioid use on outcomes after hip preservation surgery is not known. PURPOSE: To compare minimum 2-year patient-reported outcomes (PROs) between patients who required ≥1 postoperative opioid refill after undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS) versus patients who did not require a refill and to identify preoperative predictors for patients requiring ≥1 postoperative opioid refill. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Data from consecutive patients who underwent arthroscopic surgery for FAIS between January 2012 and January 2017 were analyzed. Multivariate regression analysis was performed to classify patient and radiographic variables as predictive of requiring ≥1 opioid prescription refill after surgery. Patients completed the following PROs preoperatively and at 2-year follow-up: Hip Outcome Score- Activities of Daily Living subscale (HOS-ADL), HOS-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), International Hip Outcome Tool (iHOT-12), and 100-point visual analog scale (VAS) for pain and satisfaction. Scores were compared between patients needing additional prescription opioids and those who did not. RESULTS: A total of 775 patients, of whom 141 (18.2%) required ≥1 opioid prescription refill, were included in the analysis. Patients requiring opioid refills had significantly lower 2-year postoperative PRO scores compared with patients not requiring refills: HOS-ADL (79.9 ± 20.3 vs 88.7 ± 14.9), HOS-SS (64.6 ± 29.5 vs 78.2 ± 23.7), mHHS (74.2 ± 21.1 vs 83.6 ± 15.9), iHOT-12 (63.6 ± 27.9 vs 74.9 ± 24.8), and VAS satisfaction (73.4 ± 30.3 vs 82.2 ± 24.9), as well as significantly more pain (26.8 ± 23.4 vs 17.9 ± 21.8) (P ≤ .001 for all). Predictors of requiring a postoperative opioid refill included patients with active preoperative opioid use (odds ratio, 3.12 [95% confidence interval, 1.06-9.21]; P = .039) and larger preoperative alpha angles (odds ratio, 1.04 [95% confidence interval, 1.01-1.07]; P = .03). CONCLUSION: Patients requiring ≥1 opioid prescription refill after hip arthroscopy for FAIS had lower preoperative and 2-year PRO scores when compared with patients not requiring refills. Additionally, active opioid use at the time of surgery was found to be predictive of requiring additional opioids for pain management.

Involvement of c-Jun N-terminal kinase 2 (JNK2) in Endothelin-1 (ET-1) Mediated Neurodegeneration of Retinal Ganglion Cells.

Purpose: The goal of this study was to determine whether JNK2 played a causative role in endothelin-mediated loss of RGCs in mice. Methods: JNK2-/- and wild type (C57BL/6) mice were intravitreally injected in one eye with 1 nmole of ET-1, whereas the contralateral eye was injected with the vehicle. At two time points (two hours and 24 hours) after the intravitreal injections, mice were euthanized, and phosphorylated c-Jun was assessed in retinal sections. In a separate set of experiments, JNK2-/- and wild type mice were intravitreally injected with either 1 nmole of ET-1 or its vehicle and euthanized seven days after injection. Retinal flat mounts were stained with antibodies to the RGC marker, Brn3a, and surviving RGCs were quantified. Axonal degeneration was assessed in paraphenylenediamine stained optic nerve sections. Results: Intravitreal ET-1 administration produced a significant increase in immunostaining for phospho c-Jun in wild type mice, which was appreciably lower in the JNK2 -/- mice. A significant (P < 0.05) 26% loss of RGCs was found in wild type mice, seven days after injection with ET-1. JNK2-/- mice showed a significant protection from RGC loss following ET-1 administration, compared to wild type mice injected with ET-1. A significant decrease in axonal counts and an increase in the collapsed axons was found in ET-1 injected wild type mice eyes. Conclusions: JNK2 appears to play a major role in ET-1 mediated loss of RGCs in mice. Neuroprotective effects in JNK2-/- mice following ET-1 administration occur mainly in the soma and not in the axons of RGCs.

Radiographic Prevalence of Sacroiliac Joint Abnormalities and Clinical Outcomes in Patients With Femoroacetabular Impingement Syndrome.

PURPOSE: To quantify the prevalence of sacroiliac joint (SIJ) abnormalities in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS) by use of various imaging modalities and to compare outcomes based on SIJ abnormalities. METHODS: Plain radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans of patients who underwent primary hip arthroscopy for FAIS from January 2012 to January 2016 were identified. The exclusion criteria included patients undergoing bilateral or revision surgery, those with a history of dysplasia, and those with less than 2 years' follow-up. On radiographs, the SIJs were graded using modified New York criteria for spondyloarthropathy. CT and MRI scans were reviewed for joint surface erosion, subchondral sclerosis, joint space narrowing, pseudo-widening, bone marrow edema, and ankylosis. Patients with SIJ abnormalities were matched to patients without SIJ abnormalities in a 1:2 ratio by age and body mass index. Outcomes included the Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), visual analog scale (VAS) for pain, and VAS for satisfaction. RESULTS: Of 1,009 consecutive patients, 743 (73.6%) were included; 187 (25.2%) showed SIJ changes. Of these 187 patients, 164 (87.7%) had changes on plain radiographs, 88 (47.1%) had changes on CT, and 125 (66.8%) had changes on MRI. SIJ changes on any imaging modality were weakly correlated with pain to palpation of the SIJ (r = 0.11, P = .004) on physical examination. Pain to palpation of the SIJ on physical examination (odds ratio [OR], 1.12; P = .031) and a history of SIJ pain (OR, 1.93; P = .018) increased the odds of having an SIJ abnormality on any imaging modality. After matching, patients without SIJ abnormalities had a significantly greater HOS-ADL (95.4 vs 90.6, P = .001), HOS-SS (91.1 vs 77.5, P < .001), and mHHS (91.3 vs 84.5, P < .001) and a significantly lower VAS pain score (10.9 vs 25.7, P < .001) than patients with abnormalities at a mean follow-up of 34.1 ± 9.7 months (range, 24-54 months). Patients without SIJ abnormalities had greater odds of achieving the minimal clinically important difference for the HOS-ADL (OR, 2.91; P = .001) and for the HOS-SS (OR, 2.83; P < .001) but not for the mHHS (OR, 1.73; P = .081). CONCLUSIONS: A high prevalence of SIJ abnormalities (25.2%) is seen on imaging in FAIS patients. These patients may show significantly inferior clinical outcomes and persistent postoperative pain after FAIS treatment. The results of this study may allow treating orthopaedic surgeons to better inform patients with SIJ abnormalities that they may not achieve clinically significant outcome improvement after hip arthroscopy. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Hybrid Compound SA-2 is Neuroprotective in Animal Models of Retinal Ganglion Cell Death.

Purpose: Determine the toxicity, bioavailability in the retina, and neuroprotective effects of a hybrid antioxidant-nitric oxide donor compound SA-2 against oxidative stress-induced retinal ganglion cell (RGC) death in neurodegenerative animal models. Methods: Optic nerve crush (ONC) and ischemia reperfusion (I/R) injury models were used in 12-week-old C57BL/6J mice to mimic conditions of glaucomatous neurodegeneration. Mice were treated intravitreally with either vehicle or SA-2. Retinal thickness was measured by spectral-domain optical coherence tomography (SD-OCT). The electroretinogram and pattern ERG (PERG) were used to assess retinal function. RGC survival was determined by counting RBPMS-positive RGCs and immunohistochemical analysis of superoxide dismutase 1 (SOD1) levels was carried out in the retina sections. Concentrations of SA-2 in the retina and choroid were determined using HPLC and MS. In addition, the direct effect of SA-2 treatment on RGC survival was assessed in ex vivo rat retinal explants under hypoxic (0.5% O2) conditions. Results: Compound SA-2 did not induce any appreciable change in retinal thickness, or in a- or b-wave amplitude in naive animals. SA-2 was found to be bioavailable in both the retina and choroid after a single intravitreal injection (2% wt/vol). An increase in SOD1 levels in the retina of mice subjected to ONC and SA-2 treatment, suggests an enhancement in antioxidant activity. SA-2 provided significant (P < 0.05) RGC protection in all three of the tested RGC injury models in rodents. PERG amplitudes were significantly higher in both I/R and ONC mouse eyes following SA-2 treatment (P ≤ 0.001) in comparison with the vehicle and control groups. Conclusions: Compound SA-2 was effective in preventing RGC death and loss of function in three different rodent models of acute RGC injury: ONC, I/R, and hypoxia.

Radiographic Prevalence of Symphysis Pubis Abnormalities and Clinical Outcomes in Patients With Femoroacetabular Impingement Syndrome.

BACKGROUND: The decreased hip range of motion seen in femoroacetabular impingement syndrome (FAIS) may lead to compensatory increased motion at the symphysis pubis (SP) with resultant increased stress on the joint, which can subsequently lead to osteitis pubis. PURPOSE: To quantify the prevalence of SP abnormalities in patients with FAIS through the use of imaging modalities and to compare outcomes based on the presence of SP abnormalities. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Radiographs and magnetic resonance imaging (MRI) scans of 1009 consecutive patients who underwent primary hip arthroscopy for FAIS from January 2012 to January 2016 were identified. Exclusion criteria were patients undergoing revision or bilateral surgery, patients with dysplasia, and patients with less than 2-year follow-up. On radiographs, SP joints were reviewed for joint surface erosions, subchondral sclerosis and cysts, and ankylosis. MRI scans were reviewed for marrow edema in the subarticular pubic bone, subchondral sclerosis and cysts, joint surface erosions, and ankylosis. Patients with SP abnormalities were matched 1:2 to patients without SP abnormalities by age and body mass index. Outcomes included the Hip Outcome Score-Activities of Daily Living (HOS-ADL), HOS-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), International Hip Outcome Tool-12 (iHOT-12), and visual analog scales (VAS) for pain and satisfaction. RESULTS: 830 patients were included; 23 (2.8%) demonstrated SP abnormalities. Of the 726 (72%) MRI scans reviewed, 15 (1.8%) showed bone marrow edema, subchondral sclerosis, erosions, or ankylosis. After matching, patients without SP abnormalities had significantly greater HOS-ADL (95.7 vs 83.0; P = .008), HOS-SS (91.6 vs 61.9; P = .003), iHOT-12 (89.5 vs 74.6; P = .046), and VAS satisfaction (91.3 vs 58.8; P = .004) scores, in addition to less postoperative pain (6.3 vs 23.5; P < .001). No significant differences were found in the mHHS (92.5 vs 82.2; P = .08). Patients without SP abnormalities had higher odds of achieving the minimal clinically important difference for the HOS-ADL (odds ratio [OR], 4.5; 95% CI, 1.3-14.1; P = .010), the HOS-SS (OR, 7.2; 95% CI, 1.8-18.5; P = .006), and the mHHS (OR, 14.5; 95% CI, 1.8-24.7; P = .013). CONCLUSION: A low prevalence (1.8%-2.6%) of SP joint abnormality is seen on imaging in patients with FAIS. These patients may demonstrate significantly inferior clinical outcomes and persistent postoperative pain after FAIS treatment.

KMT1 family methyltransferases regulate heterochromatin-nuclear periphery tethering via histone and non-histone protein methylation.

Euchromatic histone methyltransferases (EHMTs), members of the KMT1 family, methylate histone and non-histone proteins. Here, we uncover a novel role for EHMTs in regulating heterochromatin anchorage to the nuclear periphery (NP) via non-histone methylation. We show that EHMTs methylate and stabilize LaminB1 (LMNB1), which associates with the H3K9me2-marked peripheral heterochromatin. Loss of LMNB1 methylation or EHMTs abrogates heterochromatin anchorage at the NP We further demonstrate that the loss of EHMTs induces many hallmarks of aging including global reduction of H3K27methyl marks and altered nuclear morphology. Consistent with this, we observe a gradual depletion of EHMTs, which correlates with loss of methylated LMNB1 and peripheral heterochromatin in aging human fibroblasts. Restoration of EHMT expression reverts peripheral heterochromatin defects in aged cells. Collectively, our work elucidates a new mechanism by which EHMTs regulate heterochromatin domain organization and reveals their impact on fundamental changes associated with the intrinsic aging process.

Neuroprotective effects of curcumin on endothelin-1 mediated cell death in hippocampal neurons.

OBJECTIVES: Alzheimer's disease is a progressive neurodegenerative disease characterized by loss of hippocampal neurons leading to memory deficits and cognitive decline. Studies suggest that levels of the vasoactive peptide endothelin-1 (ET-1) are increased in the brain tissue of Alzheimer's patients. Curcumin, the main ingredient of the spice turmeric, has been shown to have anti-inflammatory, anti-cancer, and neuroprotective effects. However, the mechanisms underlying some of these beneficial effects are not completely understood. The objective of this study was to determine if curcumin could protect hippocampal neurons from ET-1 mediated cell death and examine the involvement of c-Jun in this pathway. METHODS: Primary hippocampal neurons from rat pups were isolated using a previously published protocol. Viability of the cells was measured by the live/dead assay. Immunoblot and immunohistochemical analyses were performed to analyze c-Jun levels in hippocampal neurons treated with either ET-1 or a combination of ET-1 and curcumin. Apoptotic changes were evaluated by immunoblot detection of cleaved caspase-3, cleaved fodrin, and a caspase 3/7 activation assay. RESULTS: ET-1 treatment produced a 2-fold increase in the levels of c-Jun as determined by an immunoblot analysis in hippocampal neurons. Co-treatment with curcumin significantly attenuated the ET-1 mediated increase in c-Jun levels. ET-1 caused increased neuronal cell death of hippocampal neurons indicated by elevation of cleaved caspase-3, cleaved fodrin and an increased activity of caspases 3 and 7 which was attenuated by co-treatment with curcumin. Blockade of JNK, an upstream effector of c-Jun by specific inhibitor SP600125 did not fully protect from ET-1 mediated activation of pro-apoptotic enzymes in primary hippocampal cells. DISCUSSION: Our data suggests that one mechanism by which curcumin protects against ET-1-mediated cell death is through blocking an increase in c-Jun levels. Other possible mechanisms include decreasing pro-apoptotic signaling activated by ET-1 in primary hippocampal neurons.

Is pre-operative assessment of coagulation profile with Thrombelastography (TEG) useful in predicting venous thromboembolism (VTE) following orthopaedic surgery?

INTRODUCTION: Epidemiologic data on the incidence of venous thromboembolism (VTE) in Indian population vary widely. Most studies show that the incidence of VTE is lower in Asian patients than in Western population. Screening tools to identify high-risk patients should enable us to reduce this complication. METHODS: The incidence of VTE in 101 patients who underwent knee or hip arthroplasty, or surgery for hip fractures, without chemoprophylaxis for deep vein thrombosis (DVT) was documented. Diagnosis of DVT was made with Duplex ultrasonography. We also assessed the usefulness of pre-operative assessment of the hypercoagulable status of the patient in predicting the occurrence of VTE, using the Thrombelastography (TEG) test. RESULTS: The incidence of DVT in the study population was 7%. Six of the 7 patients who developed DVT had surgery for hip fractures, while one had knee replacement. The thrombus was above the knee joint level in 6 of the 7 patients. Pre-operative TEG was positive in only one of the 7 patients, but was positive in 37 of the remaining 94 patients. CONCLUSION: Incidence of DVT in the study population is sufficiently high to recommend some form of prophylaxis to prevent VTE following hip and knee surgery. Pre-operative assessment of the patients' coagulation status with Thrombelastography does not predict the risk of VTE. The use of other lab parameters that could help in selective chemoprophylaxis needs to be explored.

Accuracy of templating the acetabular cup size in Total Hip Replacement using conventional acetate templates on digital radiographs.

OBJECTIVE: Templating of the acetabular cup size in Total Hip Replacement (THR) is normally done using conventional radiographs. As these are being replaced by digital radiographs, it has become essential to create a technique of templating using digital films. We describe a technique that involves templating the digital films using the universally available acetate templates for THR without the use of special software. MATERIALS AND METHODS: Preoperative digital radiographs of the pelvis were taken with a 30 mm diameter spherical metal ball strapped over the greater trochanter. Using standard acetate templates provided by the implant company on magnified digital radiographs, the size of the metal ball (X mm) and acetabular cup (Y mm) were determined. The size of the acetabular cup to be implanted was estimated using the formula 30*Y/X. The estimated size was compared with the actual size of the cup used at surgery. RESULTS: Using this technique, it was possible to accurately predict the acetabular cup size in 28/40 (70%) of the hips. When the accuracy to within one size was considered, templating was correct in 90% (36/40). When assessed by two independent observers, there was good intra-observer and inter-observer reliability with intra-class correlation coefficient values greater than 0.8. CONCLUSION: It was possible to accurately and reliably predict the size of the acetabular cup, using acetate templates on digital films, without any digital templates.

Distal femoral rotational alignment in the Indian population - An important consideration in total knee arthroplasty.

OBJECTIVE: To measure the angular relationships of distal femoral rotational axes in the normal Indian population. MATERIALS AND METHODS: Magnetic Resonance Imaging (MRI) scans of the knee of 40 Indian subjects were used to define the posterior condylar axis, the transepicondylar axis and the Whiteside's line (anteroposterior axis). The posterior condylar angle (PCA) - the angle between the posterior condylar axis and the transepicondylar axis, and the Whiteside-epicondylar angle (W-EP angle) were then calculated. RESULTS: The mean posterior condylar angle in the Indian knee was 4.67° and the mean Whiteside-epicondylar angle was 92.7°. CONCLUSION: There are differences in the distal femoral rotational axes among various races. The mean PCA and the W-EP angle are more externally rotated in the Indian than in the Western, population, but similar to the Chinese. Using fixed values to define the angular relationships between the axes could lead to malrotation of the femoral component. An understanding of the racial differences is essential while designing implants for the Indian population.

Fate of bone grafting for acetabular defects in total hip replacement.

BACKGROUND: The use of allografts and autografts in the management of acetabular defects have been reported with varying results. Trabecular metal is an expensive option in the management of these defects. This study aims to assess the fate and efficacy of bone grafting for acetabular bone defects in total hip arthroplasty. MATERIALS AND METHODS: A total of 30 hips in 28 patients with acetabular deficiencies were treated with bone grafting and total hip replacement (THR). Seventeen hips had American Academy of Orthopedic Surgeons (AAOS) type 2 (Paprosky type 2c) deficiency and 13 had AAOS type 3 (Paprosky type 3a) defects of the acetabulum. Allografts were used in 15 patients and autografts were used in the remaining 13. Cemented total hip arthroplasty was done in 18 hips and uncemented THR in 12. Seven patients underwent the procedure for, acetabular erosion and symptoms following hemiarthroplasty (4 out of 7), or, acetabular revision for failure (3 out of 7) following total hip arthroplasty. Acetabular deficiencies in other patients were due to posttraumatic causes, advanced primary hip arthritis and second stage treatment of postinfective arthritis. A mesh was used in 6 hips and screws were used in 13 hips for graft fixation. RESULTS: Patients were followed up clinicoradiologically for a period of 10 months to 4 years (mean 23.4 months). One patient required staged revision due to infection. Two patients had early asymptomatic cup migration. One patient had graft lysis and change in cup inclination with persistent pain. He was not keen on further intervention at last followup. Other patients were pain free at the time of followup with radiographs showing maintenance of graft and implant position. CONCLUSION: Bone grafting is a suitable option in the management of acetabular defects in total hip arthroplasty, especially in resource challenged countries.

Outcome of Schatzker type V and VI tibial plateau fractures.

BACKGROUND: Schatzker type V and VI tibial fractures are complex injuries, usually treated with open reduction and internal fixation (ORIF) using dual plates or ring fixators. ORIF has the advantage of not requiring pin tract care, but has a higher infection rate, especially in open fractures. We have combined the advantages of these two methods to treat these difficult fractures. MATERIALS AND METHODS: Ten Schatzker type V and 11 Schatzker type VI fractures were treated between 2006 and 2010. ORIF with dual plates was performed, only if there was marked articular displacement (> 2 mm) in a closed fracture. All other fractures including open fractures and closed fractures with soft tissue compromise or minimal articular displacement were treated with ring fixators. The outcomes were analyzed and documented using the Honkonen and Jarvinen subjective, clinical, functional, and radiological criteria and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). RESULTS: Nine closed fractures with marked articular displacement (> 2 mm) were treated with dual plates. Eight closed fractures with minimal articular displacement (< 2 mm) and poor skin condition and four open fractures were treated with ring fixators. The mean follow-up period was 2 ½ years. The mean postoperative knee flexion was 128°. All patients could walk, jump, and climb steps. 90% could squat, though only 50% could duck walk properly. Radiologically, 85% had a plateau tilt of less than 5°, 92% had an articular step of less than 2 mm, and a residual articular widening of less than 5 mm. There were no major infections. Two patients had minor pin tract infections and two requested that their plates be removed subsequently. CONCLUSION: The protocol used to treat Schatzker type V and VI tibial plateau fractures has had excellent results and we suggest that all open fractures be treated with ring fixators and that ORIF should be done only for closed fractures with marked displacement.

Knee extensor loss and proximal tibial soft tissue defect managed successfully with simultaneous medial gastrocnemius flap, saphenous fasciocutaneous flap and medial hemisoleus flap: a case report.

INTRODUCTION: Open fractures of the proximal tibia often pose serious challenges to the treating orthopedic surgeon. Management of these complex injuries becomes difficult if they are associated with damage to the extensor mechanism and an exposed knee joint. The scenario becomes more difficult to manage when the soft tissue defect extends to the middle third of the leg. We report a case where we used an extended medial gastrocnemius flap in combination with a saphenous artery fasciocutaneous flap and a medial hemisoleus flap for treatment of an infected proximal tibia fracture with loss of the extensor mechanism and soft tissue defect. To the best of our knowledge, combined use of these three flaps for the management of such injuries has not been reported elsewhere to date. CASE PRESENTATION: A 28-year-old Indian man presented to our Out-patient Department with complaints of pain and pus discharge from his left proximal leg for four weeks. He had sustained an open fracture of his left proximal tibia in a road traffic accident five weeks ago and had been operated on elsewhere. He had a stiff, painful knee with an infected wound of 4×4cm over the proximal third of his leg exposing infected, necrotic patellar tendon. He was successfully managed with debridement and simultaneously elevated flaps as described. CONCLUSIONS: This procedure avoids the donor site morbidity associated with free flaps harvested from sites distant from the site of injury, and also does not need the expertise of microvascular reconstruction. To the best of our knowledge, this is also the first report of the combined use of three local flaps for knee extensor reconstruction and soft tissue coverage around the knee.