A knee-specific finite element analysis of the human anterior cruciate ligament impingement against the femoral intercondylar notch

This work presents a finite element analysis of anterior cruciate ligament (ACL) impingement against the intercondylar notch during tibial external rotation and abduction, as a mechanism of noncontact ACL injuries. Experimentally, ACL impingement was measured in a cadaveric knee in terms of impingement contact pressure and six degrees-of-freedom tibiofemoral kinematics. Three-dimensional geometries of the ACL, femur and tibia were incorporated into the finite element model of the individual knee specimen. A fiber-reinforced model was adopted, which accounts for the anisotropy, large deformation, nonlinearity and incompressibility of the ACL. With boundary conditions specified based on the experimental tibiofemoral kinematics, the finite element analysis showed that impingement between the ligament and the lateral wall of intercondylar notch could occur when qthe knee at 45° was externally rotated at 29.1° and abducted at 10.0°. Strong contact pressure and tensile stress occurred at the impinging and nonimpinging sides of the ligament, respectively. The impingement force and contact area estimated from the model matched their counterparts from the corresponding cadaver experiment. The modeling and experimental approach provides a useful tool to characterize potential ACL impingement on a knee-specific basis, which may help elucidate the ACL injury mechanism and develop more effective treatments.     

Contribution of antigen-primed CD8+ T cells to the development of airway hyperresponsiveness and inflammation is associated with IL-13

The role of Th2/CD4 T cells, which secrete IL-4, IL-5, and IL-13, in allergic disease is well established; however, the role of CD8(+) T cells (allergen-induced airway hyperresponsiveness (AHR) and inflammation) is less clear. This study was conducted to define the role of Ag-primed CD8(+) T cells in the development of these allergen-induced responses. CD8-deficient (CD8(-/-)) mice and wild-type mice were sensitized to OVA by i.p. injection and then challenged with OVA via the airways. Compared with wild-type mice, CD8(-/-) mice developed significantly lower airway responsiveness to inhaled methacholine and lung eosinophilia, and exhibited decreased IL-13 production both in vivo, in the bronchoalveolar lavage (BAL) fluid, and in vitro, following Ag stimulation of peribronchial lymph node (PBLN) cells in culture. Reconstitution of sensitized and challenged CD8(-/-) mice with allergen-sensitized CD8(+) T cells fully restored the development of AHR, BAL eosinophilia, and IL-13 levels in BAL and in culture supernatants from PBLN cells. In contrast, transfer of naive CD8(+) T cells or allergen-sensitized CD8(+) T cells from IL-13-deficient donor mice failed to do so. Intracellular cytokine staining of lung as well as PBLN T cells revealed that CD8(+) T cells were a source of IL-13. These data suggest that Ag-primed CD8(+) T cells are required for the full development of AHR and airway inflammation, which appears to be associated with IL-13 production from these primed T cells.     

Metabolic pathways and fermentative production of L-aspartate family amino acids

The L -aspartate family amino acids (AFAAs), L -threonine, L -lysine, L -methionine and L -isoleucine have recently been of much interest due to their wide spectrum of applications including food additives, components of cosmetics and therapeutic agents, and animal feed additives. Among them, L -threonine, L -lysine and L -methionine are three major amino acids produced currently throughout the world. Recent advances in systems metabolic engineering, which combine various high-throughput omics technologies and computational analysis, are now facilitating development of microbial strains efficiently producing AFAAs. Thus, a thorough understanding of the metabolic and regulatory mechanisms of the biosynthesis of these amino acids is urgently needed for designing system-wide metabolic engineering strategies. Here we review the details of AFAA biosynthetic pathways, regulations involved, and export and transport systems, and provide general strategies for successful metabolic engineering along with relevant examples. Finally, perspectives of systems metabolic engineering for developing AFAA overproducers are suggested with selected exemplary studies.     

Differential expression of 10 sweetpotato peroxidase genes in response to bacterial pathogen, Pectobacterium chrysanthemi.

To understand the function of each peroxidase (POD, EC 1.11.1.7) in terms of biotic stress, changes in POD specific activity and expression of 10 POD genes were investigated in four cultivars of sweetpotato (Ipomoea batatas) after infection with Pectobacterium chrysanthemi. POD specific activity (units mg(-1) protein) increased from 16 h after inoculation (HAI) in three varieties. POD activities of two cultivars, Shinwhangmi and White Star, reached a maximum level at 24 HAI by about three times compared to mock treatment (MT), and then decreased, whereas those of Zami and Yulmi continuously increased until 36 HAI. Native gel analysis revealed that one POD isoenzyme with a high electrophoretic mobility significantly increased in response to pathogen infection in all cultivars. Additionally, 10 POD genes displayed differential expression patterns upon bacterial infection by northern analysis. Several POD genes such as swpa2, swpa3, swpa4, swpa5, swpb1 were induced upon bacterial infection, but other genes were not. Particularly, swpa4 gene was markedly expressed in response to bacterial infection in four different cultivars, suggesting that this gene has a stress-inducible promoter. These results indicate that some specific POD isoenzymes are involved in defense in relation to pathogenesis of P. chrysanthemi in sweetpotato plants.     

Prediction of novel synthetic pathways for the production of desired chemicals

Background  

There have been several methods developed for the prediction of synthetic metabolic pathways leading to the production of desired chemicals. In these approaches, novel pathways were predicted based on chemical structure changes, enzymatic information, and/or reaction mechanisms, but the approaches generating a huge number of predicted results are difficult to be applied to real experiments. Also, some of these methods focus on specific pathways, and thus are limited to expansion to the whole metabolism.     

Purification and biochemical characterization of a 17 kDa fibrinolytic enzyme from <Emphasis Type="Italic">Schizophyllum commune</Emphasis>

A fibrinolytic enzyme of the mushroom, Schizophyllum commune was purified with chromatographic methods, including a DEAE-Sephadex A-50 ion-exchange column and gel filtrations with Sephadex G-75 and Sephadex G-50 columns. The analysis of fibrin-zymography and SDS-PAGE showed that the enzyme was a monomeric subunit that was estimated to be approximately 17 kDa in size. The fibrinolytic activity of the enzyme in plasminogen-rich and plasminogen-free fibrin plates was 1.25 and 0.44 U/ml, respectively. The N-terminal amino acid sequence of the purified enzyme was identified as HYNIXNSWSSFID, which was highly distinguished from known fibrinolytic enzymes. The relative activity of the purified enzyme with an addition of 5 mM EDTA, Phosphoramidon, and Bestatin was about 76, 64, and 52%, respectively, indicating that it is a metalloprotease. The optimum temperature for the purified enzyme was approximately 45°C, and over 87% of the enzymatic activity was maintained as a stable state in a pH range from 4.0 to 6.0. Therefore, our results suggest that the potential thrombolytic agent from S. commune is a unique type of fibrinolytic enzyme.     

Protective effect of ginseng sapogenins against 2,2'-azobis (1-aminopropane) dihydrochloride (AAPH)-induced LLC-PK₁ cell damage

The effect of ginseng sapogenins, aglycone parts of ginsenosides, against oxidative damage by radical generator, 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH), in renal epithelial LLC-PK(1) cells was investigated to identify the structural characteristics of sapogenins to have renoprotective effects. Of the tested sapogenins, Δ(20(21))-protopanaxatriol showed the strongest protective effect against the AAPH-induced LLC-PK(1) cell damage. Based on the structure and stronger activity of Δ(20(21))-protopanaxatriol than the other sapogenins, the hydroxyl group in C-6 and double bond in C-20(21) position were important for renoprotective effect of sapogenin against oxidative stress.     

Hox proteins coordinate peripodial decapentaplegic expression to direct adult head morphogenesis in Drosophila

The Drosophila BMP, decapentaplegic (dpp), controls morphogenesis of the ventral adult head through expression limited to the lateral peripodial epithelium of the eye-antennal disc by a 3.5kb enhancer in the 5' end of the gene. We recovered a 15bp deletion mutation within this enhancer that identified a homeotic (Hox) response element that is a direct target of labial and the homeotic cofactors homothorax and extradenticle. Expression of labial and homothorax are required for dpp expression in the peripodial epithelium, while the Hox gene Deformed represses labial in this location, thus limiting its expression and indirectly that of dpp to the lateral side of the disc. The expression of these homeodomain genes is in turn regulated by the dpp pathway, as dpp signalling is required for labial expression but represses homothorax. This Hox-BMP regulatory network is limited to the peripodial epithelium of the eye-antennal disc, yet is crucial to the morphogenesis of the head, which fate maps suggest arises primarily from the disc proper, not the peripodial epithelium. Thus Hox/BMP interactions in the peripodial epithelium of the eye-antennal disc contribute inductively to the shape of the external form of the adult Drosophila head.