Central defect type partial ACL injury model on goat knees: the effect of infrapatellar fat pad excision

BACKGROUND: The mid-substance central defect injury has been used to investigate the primary healing capacity of the anterior cruciate ligament (ACL) in a goat model. The sagittal plane stability on this model has not been confirmed, and possible effects of fat pad excision on healing have not been evaluated. We hypothesize that excising the fat pad tissue results in poorer ligament healing as assessed histologically and decreased tensile strength of the healing ligament. We further hypothesize that the creation of a central defect does not affect sagittal plane knee stability. METHODS: A mid-substance central defect was created with a 4-mm arthroscopic punch in the ACLs of right knees of all the subjects through a medial mini-arthrotomy. Goats were assigned to groups based on whether the fat pad was preserved (group 1, n = 5) or excised completely (group 2, n = 5). The left knees served as controls in each goat. Histopathology of the defect area along with measurement of type I collagen in one goat from each group were performed at 10th week postoperatively. The remaining knees were evaluated biomechanically at the 12th week, by measuring anterior tibial translation (ATT) of the knee joints at 90° of flexion and testing tensile properties (ultimate tensile load (UTL), ultimate elongation (UE), stiffness (S), failure mode (FM)) of the femur-ACL-tibia complex. RESULTS AND DISCUSSION: Histopathology analysis revealed that the central defect area was fully filled macroscopically and microscopically. However, myxoid degeneration and fibrosis were observed in group 2 and increased collagen type I content was noted in group 2. There were no significant differences within and between groups in terms of ATT values (p = 0.715 and p = 0.149, respectively). There were no significance between or within groups in terms of ultimate tensile load and ultimate elongation; however, group 2 demonstrated greater stiffness than group 1 that was correlated with the fibrotic changes detected microscopically (p = 0.043). CONCLUSIONS: The central defect type injury model was confirmed to be biomechanically stable in a goat model. Resection of the fat pad was noted to negatively affect defect healing and increase ligament stiffness in the central defect injury model

Inhibition of Reactive Gliosis Attenuates Excitotoxicity-Mediated Death of Retinal Ganglion Cells

Reactive gliosis is a hallmark of many retinal neurodegenerative conditions, including glaucoma. Although a majority of studies to date have concentrated on reactive gliosis in the optic nerve head, very few studies have been initiated to investigate the role of reactive gliosis in the retina. We have previously shown that reactive glial cells synthesize elevated levels of proteases, and these proteases, in turn, promote the death of retinal ganglion cells (RGCs). In this investigation, we have used two glial toxins to inhibit reactive gliosis and have evaluated their effect on protease-mediated death of RGCs. Kainic acid was injected into the vitreous humor of C57BL/6 mice to induce reactive gliosis and death of RGCs. C57BL/6 mice were also treated with glial toxins, alpha-aminoadipic acid (AAA) or Neurostatin, along with KA. Reactive gliosis was assessed by immunostaining of retinal cross sections and retinal flat-mounts with glial fibrillary acidic protein (GFAP) and vimentin antibodies. Apoptotic cell death was assessed by TUNEL assays. Loss of RGCs was determined by immunostaining of flat-mounted retinas with Brn3a antibodies. Proteolytic activities of matrix metalloproteinase-9 (MMP-9), tissue plasminogen activator (tPA), and urokinase plasminogen activator (uPA) were assessed by zymography assays. GFAP-immunoreactivity indicated that KA induced reactive gliosis in both retinal astrocytes and in Muller cells. AAA alone or in combination with KA decreased GFAP and vimentin-immunoreactivity in Mϋller cells, but not in astrocytes. In addition AAA failed to decrease KA-mediated protease levels and apoptotic death of RGCs. In contrast, Neurostatin either alone or in combination with KA, decreased reactive gliosis in both astrocytes and Mϋller cells. Furthermore, Neurostatin decreased protease levels and prevented apoptotic death of RGCs. Our findings, for the first time, indicate that inhibition of reactive gliosis decreases protease levels in the retina, prevents apoptotic death of retinal neurons, and provides substantial neuroprotection

Delayed Appearance of High Altitude Retinal Hemorrhages

When closely examined, a very large amount of climbers exhibit retinal hemorrhages during exposure to high altitudes. The incidence of retinal hemorrhages may be greater than previously appreciated as a definite time lag was observed between highest altitude reached and development of retinal bleeding. Retinal hemorrhages should not be considered warning signs of impending severe altitude illness due to their delayed appearance

An IL1RL1 genetic variant lowers soluble ST2 levels and the risk effects of APOE-ε4 in female patients with Alzheimer’s disease

Changes in the levels of circulating proteins are associated with Alzheimer’s disease (AD), whereas their pathogenic roles in AD are unclear. Here, we identified soluble ST2 (sST2), a decoy receptor of interleukin-33–ST2 signaling, as a new disease-causing factor in AD. Increased circulating sST2 level is associated with more severe pathological changes in female individuals with AD. Genome-wide association analysis and CRISPR–Cas9 genome editing identified rs1921622, a genetic variant in an enhancer element of IL1RL1, which downregulates gene and protein levels of sST2. Mendelian randomization analysis using genetic variants, including rs1921622, demonstrated that decreased sST2 levels lower AD risk and related endophenotypes in females carrying the Apolipoprotein E (APOE)-ε4 genotype; the association is stronger in Chinese than in European-descent populations. Human and mouse transcriptome and immunohistochemical studies showed that rs1921622/sST2 regulates amyloid-beta (Aβ) pathology through the modulation of microglial activation and Aβ clearance. These findings demonstrate how sST2 level is modulated by a genetic variation and plays a disease-causing role in females with AD

Biomechanical considerations in the pathogenesis of osteoarthritis of the knee

Osteoarthritis is the most common joint disease and a major cause of disability. The knee is the large joint most affected. While chronological age is the single most important risk factor of osteoarthritis, the pathogenesis of knee osteoarthritis in the young patient is predominantly related to an unfavorable biomechanical environment at the joint. This results in mechanical demand that exceeds the ability of a joint to repair and maintain itself, predisposing the articular cartilage to premature degeneration. This review examines the available basic science, preclinical and clinical evidence regarding several such unfavorable biomechanical conditions about the knee: malalignment, loss of meniscal tissue, cartilage defects and joint instability or laxity

Abstract P5-01-03: Discordant Estrogen and Progesterone Receptor Status in Breast Cancer

Abstract Introduction: Hormone receptor status is used to guide clinical therapy in breast cancer. Estrogen receptor (ER) assays from pathology reports have been shown to be in agreement with ER measured by a centralized laboratory on tissue microarray 87% of the time (Kappa = 0.64); however, little is known of reproducibility within subsets of patients defined by ER/PR status (1). Methods: We computed percent agreement and Kappa statistics for ER/PR status as reported in pathology reports from Nurse's Health Study (NHS) participants with breast cancer from 1976 to 2000, and as scored by immunohistochemistry (IHC) on tissue microarrays at a central laboratory (n = 2011). Statistics were computed separately for 4 subsets of patients stratified by ER/PR status as defined by pathology reports (ER+/PR+, ER+/PR−, ER−/PR+, ER−/PR−). We also used a curated compilation of publicly available gene expression data sets providing both IHC and microarray data on ER and PR expression (n = 1236). Results: We observed significant heterogeneity in Kappa values across the four groups of patients, with ER+/PR+ and ER−/PR- showing the strongest agreement, ER+/PR- showing fair agreement, and ER−/PR+ showing no significant agreement: 89.1% of ER+/PR+ cases from medical record were ER+/PR+ by TMA (κ=.60), 69.4% of ER−/PR- cases from medical record were ER−/PR- by TMA (κ=.63), 42% of ER+/PR- cases from medical record were ER+/PR- by TMA (κ=.37), and only 6% of cases of ER−/PR+ cases from medical record were ER−/PR+ by TMA (κ=.06). Using publicly available microarray data, we observed similar results comparing IHC to gene expression data in the same samples. Expression values were scaled across patients, and a patient was classified as positive for the marker by microarray if the scaled expression value was greater than zero. The agreement between IHC data and gene expression-based classification was 50.0% (k = .50), 80.8% (κ=.54), 42.0% (κ=.15), and 7.2% (κ = −.006) for ER+/PR+, ER−/PR−, ER+/PR−, and ER−/PR+, respectively. Conclusion: ER−/PR+ is by far the most rare and least reproducible subset of breast cancer cases. Given the lack of reproducibility of the ER−/PR+ group and the minimal reported benefit from hormonal therapy in these patients (2), these data question the clinical utility of assessment of PR, particularly in ER− breast cancer. 1. Collins LC, Marotti JD, Baer HJ, Tamimi RM. Comparison of estrogen receptor results from pathology reports with results from central laboratory testing. Journal of the National Cancer Institute. 2008;100(3):218–21. 2. Anderson H, Hills M, Zabaglo L, A'Hern R, Leary AF, Haynes BP, et al. Relationship between estrogen receptor, progesterone receptor, HER-2 and Ki67 expression and efficacy of aromatase inhibitors in advanced breast cancer. Annals of oncology: official journal of the European Society for Medical Oncology/ESMO. 2011;22(8):1770–6. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-01-03.</jats:p