Unicompartmental knee arthroplasty (UKA) has become a popular method of treating knee localized osteoarthritis (OA). Additionally, the posterior cruciate ligament (PCL) is essential to maintaining ...the physiological kinematics and functions of the knee joint. Considering these factors, the purpose of this study was to investigate the biomechanical effects on PCL-deficient knees in medial UKA.
Computational simulations of five subject-specific models were performed for intact and PCL-deficient UKA with tibial slopes. Anteroposterior (AP) kinematics and contact stresses of the patellofemoral (PF) joint and the articular cartilage were evaluated under the deep-knee-bend condition.
As compared to intact UKA, there was no significant difference in AP translation in PCL-deficient UKA with a low flexion angle, but AP translation significantly increased in the PCL-deficient UKA with high flexion angles. Additionally, the increased AP translation became decreased as the posterior tibial slope increased. The contact stress in the PF joint and the articular cartilage significantly increased in the PCL-deficient UKA, as compared to the intact UKA. Additionally, the increased posterior tibial slope resulted in a significant decrease in the contact stress on PF joint but significantly increased the contact stresses on the articular cartilage.
Our results showed that the posterior stability for low flexion activities in PCL-deficient UKA remained unaffected; however, the posterior stability for high flexion activities was affected. This indicates that a functional PCL is required to ensure normal stability in UKA. Additionally, posterior stability and PF joint may reduce the overall risk of progressive OA by increasing the posterior tibial slope. However, the excessive posterior tibial slope must be avoided.Cite this article:
2020;9(9):593-600.
The angiopoietin-Tie2 system in endothelial cells is an important regulator of vasculogenesis and vascular integrity. High levels of angiopoietin-2 (Ang2) mRNA are observed in vascular activation ...during tumorigenesis. Although Ang2 is known to be a naturally occurring antagonist of angiopoietin-1 (Ang1) in vivo, the exact function of Ang2 itself is not known. Here, we found that a high concentration of Ang2 (800 ng/ml) acts as an apoptosis survival factor for endothelial cells during serum deprivation apoptosis. The survival effect of high concentration Ang2 was blocked by pre-treatment with soluble Tie2 receptor and the PI 3'-kinase-specific inhibitors, wortmannin and LY294002. Accordingly, 800 ng/ml of Ang2 induced phosphorylation of Tie2, the p85 subunit of phosphatidylinositol 3'-kinase (PI 3'-kinase), and serine-threonine kinase Akt at Ser473 in the human umbilical vein endothelial cells; lower concentrations of Ang2 (50 - 400 ng/ml) did not produce notable effects. These findings indicate that at high concentrations, Ang2, like Ang1, can be an apoptosis survival factor for endothelial cells through the activation of the Tie2 receptor, PI 3'-kinase and Akt, and thus may be a positive regulator of tumor angiogenesis. Oncogene (2000) 19, 4549 - 4552.
A total of 245 patients with confirmed 2009 H1N1 influenza were admitted to the intensive-care units of 28 hospitals (South Korea). Their mean age was 55·3 years with 68·6% aged >50 years, and 54·7% ...male. Nine were obese and three were pregnant. One or more comorbidities were present in 83·7%, and nosocomial acquisition occurred in 14·3%. In total, 107 (43·7%) patients received corticosteroids and 66·1% required mechanical ventilation. Eighty (32·7%) patients died within 30 days after onset of symptoms and 99 (40·4%) within 90 days. Multivariate logistic regression analysis showed that the clinician's decision to prescribe corticosteroids, older age, Sequential Organ Failure Assessment score and nosocomial bacterial pneumonia were independent risk factors for 90-day mortality. In contrast with Western countries, critical illness in Korea in relation to 2009 H1N1 was most common in older patients with chronic comorbidities; nosocomial acquisition occurred occasionally but disease in obese or pregnant patients was uncommon.
The administration of neuraminidase inhibitors (NAIs) within 2 days after the onset of symptoms (early NAI therapy) has been shown to reduce mortality in adult patients with severe influenza. ...However, there is no sufficiently solid evidence supporting the effectiveness of early NAI therapy on mortality. We reviewed the clinical data from 506 adult patients who were hospitalized for influenza between March 2010 and March 2014, to investigate the impact of early NAI therapy on mortality. Nearly one-third of the study patients were infected with influenza B (influenza A, influenza B, and co-infection of both in 68.8%, 28.1%, and 3.2%, respectively), and were diagnosed using the polymerase chain reaction (PCR) method (33.6%). Less than half (233, 46.0%) had received early NAI therapy. Patients with early NAI therapy were admitted to the hospital earlier, more frequently infected with influenza A, and more frequently diagnosed using rapid influenza detection tests compared to those without early NAI therapy. Although patients without early NAI therapy presented with more serious clinical manifestations, such as an initial symptom of dyspnea, pneumonia, and intensive care unit admission, than those with early NAI therapy, the in-hospital mortality of the former (2.9%, 8/273) did not differ from that of the latter (3.4%, 8/233) (
p
= 0.75). We did not find a reduction in mortality associated with early NAI therapy in adult patients hospitalized for influenza. Further clinical studies including a large number of influenza B-infected patients with virus identification using PCR methodology rather than viral culture may be required to confirm the beneficial impact of early NAI therapy on mortality.
Abstract The Korean Superconducting Tokamak Advanced Research has been focused on exploring the key physics and engineering issues for future fusion reactors by demonstrating the long pulse operation ...of high beta steady-state discharge. Advanced scenarios are being developed with the goal for steady-state operation, and significant progress has been made in high ℓ i , hybrid and high beta scenarios with β N of 3. In the new operation scenario called fast ion regulated enhanced (FIRE), fast ions play an essential role in confinement enhancement. GK simulations show a significant reduction of the thermal energy flux when the thermal ion fraction decreases and the main ion density gradient is reversed by the fast ions in FIRE mode. Optimization of 3D magnetic field techniques, including adaptive control and real-time machine learning control algorithm, enabled long-pulse operation and high-performance ELM-suppressed discharge. Symmetric multiple shattered pellet injections (SPIs) and real-time disruption event characterization and forecasting are being performed to mitigate and avoid the disruptions associated with high-performance, long-pulse ITER-like scenarios. Finally, the near-term research plan will be addressed with the actively cooled tungsten divertor, a major upgrade of the NBI and helicon current drive heating, and transition to a full metallic wall.
We examined the effect of angiopoietin-1 (Ang1) on apoptosis in human umbilical vein endothelial cells (HUVECs). Ang1 (5–1000 ng/ml) dose-dependently inhibited apoptosis under a serum-deprived state. ...A significant apoptotic inhibition occurred with as low as 50 ng/ml. Two hundred ng/ml of Ang1 inhibited to approximately 50% of the control apoptotic rates for 96 h. Furthermore, an augmented antiapoptotic effect of Ang1 by the addition of 20 ng/ml vascular endothelial growth factor was observed. This Ang1-induced strong antiapoptotic effect in endothelial cells is a novel and intriguing finding and could be an additional description of Ang1-induced direct biological function.
We examined the prevalence and characteristics of extended-spectrum beta-lactamase (ESBL)-producing clinical isolates among Enterobacter spp., Serratia marcescens, Citrobacter freundii, and ...Morganella morganii, and evaluated screening criteria, clinical characteristics and outcomes of infections caused by ESBL-producing organisms. Between January and June 2005, a total of 493 nonduplicate consecutive isolates were collected at Asan Medical Center, a 2,300-bed tertiary hospital in Seoul, Republic of Korea. Fifty isolates (10.1%) were positive for phenotypical ESBL-test. The positive rate of phenotypical ESBL-test in Enterobacter spp., S. marcescens, C. freundii, and M. morganii was 12.8%, 12.4%, 4.9%, and 0% respectively. SHV-12 (18 isolates), CTX-M-9 (17 isolates), and TEM-52 (five isolates) were the most prevalent ESBL types. The ESBL in 17 strains could not be identified. As an ESBL screening criterion, the cefepime MIC >or=1 microg/ml had the highest sensitivity (0.84) and specificity (0.87). Half of the ESBL-producing isolates (25/50) were judged as pathogens. Cholangitis (ten cases), and pneumonia (six cases) were the most common infections. The overall mortality was 12.0%.
The RNA world hypothesis presumes that RNA will be competent for varied essential cellular functions. One such indispensable cell function is regulation of membrane permeability. Though this was not ...a known RNA activity, selection-amplification yielded RNAs that bound phosphatidylcholine:cholesterol liposomes. At least eight distinct, ≈ 95-mer sequences bind well to the outside of the lipid bilayer, though randomized sequences had no such activity. No distinct sequence motif for lipid binding was found. However, truncation of one such RNA shows that a smaller, 44-nucleotide irregular RNA hairpin is an active membrane binding domain. Bound RNA increases the permeability of liposomes to22Na+. In addition, using voltage clamp technique, four individual RNAs increase the ion permeability of the plasma membrane of cultured human cells. The existence of multiple sequences that bind membranes and provoke permeability changes suggests that these may be elementary RNA functions that could be selected in vivo.
Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that has a central role in the regulation of tumour metabolism under hypoxic conditions. HIF-1 stimulates glycolytic energy production and ...promotes tumour growth. Sirtuins are NAD+-dependent protein deacetylases that regulate cellular metabolism in response to stress; however, their involvement in the hypoxic response remains unclear. In this study, it is shown that SIRT2-mediated deacetylation of HIF-1 regulates its stability in tumour cells. SIRT2 overexpression destabilized HIF-1 under hypoxic conditions, whereas HIF-1 protein levels were high in SIRT2-decient cells. SIRT2 directly interacted with HIF-1 and deacetylated Lys709 of HIF-1. Deacetylation of HIF-1 by SIRT2 resulted in increased binding afnity for prolyl hydroxylase 2, a key regulator of HIF-1 stability, and increased HIF-1 hydroxylation and ubiquitination. Moreover, a pharmacological agent that increased the intracellular NAD+/NADH ratio led to the degradation of HIF-1 by increasing SIRT2-mediated deacetylation and subsequent hydroxylation. These ndings suggest that SIRT2-mediated HIF-1 deacetylation is critical for the destablization of HIF-1 and the hypoxic response of tumour cells.
Using degenerate polymerase chain reaction, we isolated a cDNA encoding a novel 493-amino acid protein from human and mouse adult heart cDNAs and have designated it angiopoietin-related protein-2 ...(ARP2). The NH(2)-terminal and COOH-terminal portions of ARP2 contain the characteristic coiled-coil domain and fibrinogen-like domain that are conserved in angiopoietins. ARP2 has two consensus glycosylation sites and a highly hydrophobic region at the NH(2) terminus that is typical of a secretory signal sequence. Recombinant ARP2 expressed in COS cells is secreted and glycosylated. In human adult tissues, ARP2 mRNA is most abundant in heart, small intestine, spleen, and stomach. In rat embryos, ARP2 mRNA is most abundant in the blood vessels and skeletal muscles. Endothelial and vascular smooth muscle cells also contain ARP2 mRNA. Recombinant ARP2 protein induces sprouting in vascular endothelial cells but does not bind to the Tie1 or Tie2 receptor. These results suggest that ARP2 may exert a function on endothelial cells through autocrine or paracrine action.
PDF
