个体化下肢小腿假肢接受腔设计的生物力学评价技术研究

作为传递体重、固定假肢的部件 ,接受腔对于小腿假肢使用的舒适性和方便程度有决定性的作用。本研究建立了基于有限元应力分析的小腿假肢生物力学评价技术平台 ,实现了小腿残端 /接受腔 3D几何建模与信息交互、三维有限元自动建模及应力分析。 3D模型与信息交互的实现基于得到广泛支持的OpenGL技术 ,有限元模型的构建采用了专门针对小腿残端 /接受腔结构特点的自动建模方法 ,通过构建档案数据库系统作为整个系统的操作平台。该技术平台可与现有的CAD/CAM系统相结合 ,为接受腔的个体化设计提供生物力学定量化依据。其临床应用将改善传统的设计流程 ,提高设计效率。同时 ,它也是未来构建接受腔设计专家 /智能系统的基础。     

Relationship between Candida albicans virulence during experimental hematogenously disseminated infection and endothelial cell damage in vitro

Candida albicans must penetrate the endothelial cell lining of the vasculature to invade the deep tissues during a hematogenously disseminated infection. We compared 27 C. albicans mutants with their wild-type parent for their capacity to damage endothelial cells in vitro and cause a lethal infection in mice following tail vein inoculation. Of 10 mutants with significantly impaired capacity to damage endothelial cells, all had attenuated virulence. Therefore, the endothelial cell damage assay can be used as a screen to identify some virulence factors relevant to hematogenously disseminated candidiasis.     

Dendritic spine abnormalities in the occipital cortex of C57BL/6 Fmr1 knockout mice.

Fragile X syndrome (FXS) is the most common form of inherited mental retardation. Observed neuropathologies associated with FXS include abnormal length, morphology, and density of dendritic spines, reported in individuals with FXS and in Fmr1 knockout (KO) mice, an animal model of FXS. To date, however, these neuropathologies have been studied in Fmr1 KO mice bred in a FVB background (a strain with genetic mutations that complicate interpretation of results) and findings have been inconsistent. Here, Golgi-Cox impregnation was used to investigate length, morphology, and density of dendritic spines on layer V pyramidal neurons in visual cortices of Fmr1 KO and wildtype (WT) mice bred in a C57BL/6 background. We report that spine abnormalities in these animals parallel abnormalities reported in humans with FXS, perhaps to a greater degree than KO mice bred in an FVB background. Specifically, Fmr1 KO mice bred in a C57BL/6 background exhibited significantly more longer dendritic spines and fewer shorter spines, as well as more spines with immature-appearing morphology and fewer with mature-appearing morphology than WT littermates. Spine length abnormalities were demonstrated to be largely independent of spine morphology abnormalities, as the length phenotype was observed in KOs even within a morphological category. Fmr1 KO mice also had a greater overall spine density than WTs. These findings provide powerful support for the essence of the dendritic spine abnormalities in the absence of FMRP, now found to be largely consistent with human data across two mouse backgrounds.     

Germinal center and activated b-cell profiles separate Burkitt lymphoma and diffuse large B-cell lymphoma in AIDS and non-AIDS cases

Morphologic features of Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) overlap. No single phenotypic marker or molecular abnormality is pathognomonic. We tested a panel of 8 germinal center (GC) and activated B-cell (ABC) markers for their ability to separate BL and DLBCL. We diagnosed 16 BL and 39 DLBCL cases from 21 patients with AIDS and 34 without AIDS based on traditional morphologic criteria, Ki-67 proliferative index, and c-myc rearrangement (fluorescence in situ hybridization). After immunohistochemically staining tissue microarrays of BL and DLBCL for markers of GC (bcl-6, CD10, cyclin H) and ABC (MUM1, CD138, PAK1, CD44, bcl-2), we scored each case for the percentage of positive cells. Hierarchical clustering yielded 2 major clusters significantly associated with morphologic diagnosis (P < .001). For comparison, we plotted the sum of the GC scores and ABC scores for each case as x and y data points. This revealed a high-GC/low-ABC group and a low-GC/high-ABC group that were associated significantly with morphologic diagnosis (P < .001). Protein expression of multiple GC and ABC markers can separate BL and DLBCL.     

Specificity of blebbistatin, an inhibitor of myosin II

Blebbistatin is a small molecule inhibitor discovered in a screen for inhibitors of nonmuscle myosin IIA. We have examined the specificity and potency of the drug by assaying its effects on the actin-activated MgATPase assay of diverse members of the myosin superfamily. Blebbistatin potently inhibits several striated muscle myosins as well as vertebrate nonmuscle myosin IIA and IIB with IC₅₀ values ranging from 0.5 to 5 μM. Interestingly, smooth muscle which is highly homologous to vertebrate nonmuscle myosin is only poorly inhibited (IC₅₀=80 μM). The drug potently inhibits Dictyostelium myosin II, but poorly inhibits Acanthamoeba myosin II. Blebbistatin did not inhibit representative myosin superfamily members from classes I, V, and X. This revised version was published online in July 2006 with corrections to the Cover Date.     

CD39 activity correlates with stage and inhibits platelet reactivity in chronic lymphocytic leukemia

Background  

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of mature appearing lymphocytes and is rarely complicated by thrombosis. One possible explanation for the paucity of thrombotic events in these patients may be the presence of the ecto-nucleotidase CD39/NTDPase-1 on the surface of the malignant cells in CLL. CD39 is the major promoter of platelet inhibition in vivo via its metabolism of ADP to AMP. We hypothesize that if CD39 is observed on CLL cells, then patients with CLL may be relatively protected against platelet aggregation and recruitment and that CD39 may have other effects on CLL, including modulation of the disease, via its metabolism of ATP.     

Nonrandomness of D-group chromosomes involved in centric-fusion translocation

Ten members of two families with D/G translocation, three members of a family with D/D translocation, and one patient with non-familial and one with apparently non-familial D/D translocation were examined. The trdnslocation chromosomes were identified by SH-thymidine labeling and autoradio-graphy as 14q21q and 13q14q, respectively. These findings support the hypothesis of nonrandomness of D group chromosomes involved in centric-fusion translocation. The importance of the identification of Dgroup chromosomes involved in centriofusion translocation in relation to genetic counseling is discussed.     

Phylogeny and sequence variability of the Sarcocystis singaporensis Zaman and Colley, (1975) 1976 ssrDNA

The coccidium Sarcocystis singaporensis (Apicomplexa: Sarcocystidae) is a cyst-forming parasite with potential as a biological agent for the control of wild populations of rodents in non-native environments. Phylogenetic analysis based on the ssrDNA supports S. singaporensisisolates as a sister species to sarcosporidians transmitted between snakes and rodents but an association with the carnivore-ruminant Sarcocystis spp. could not be rejected by likelihood ratio tests. Four complete and six partial ssrDNA sequences representing this species are monophyletic in any tree reconstruction method; however, they possess very high pairwise distances of up to 0.053. The obtained sequences suggest the probable existence of at least two divergent paralogous ssrDNAs. Moreover, our results support the co-evolution of lsrDNA and ssrDNA in S. singaporensis. The utility of coccidian lsrDNA and ssrDNA for evolutionary studies and their abundance in the primary nucleotide databases is discussed.     

Involvement of central amygdalar and bed nucleus of the stria terminalis corticotropin-releasing factor in behavioral responses to social defeat

The authors investigated whether corticotropin-releasing factor (CRF) within the central nucleus of the amygdala (CeA) and bed nucleus of the stria terminalis (BNST) is a critical component of the neural circuitry mediating conditioned defeat. In this model, hamsters that have experienced social defeat subsequently display only submissive-defensive agonistic behavior instead of territorial aggression. Conditioned defeat was significantly reduced following infusion of the CRF receptor antagonist D-Phe CRF((12-41)) into the BNST but not into the CeA. In another experiment, hamsters given unilateral lesions of the CeA and infusions of D-Phe CRF((12-41)) into the contralateral BNST displayed significantly less submissive behavior than did controls. These data suggest that CRF acts within a neural circuit that includes the amygdala and the BNST to modulate agonistic behavior following social defeat.