产ESBLs菌株的TEM型基因检测及其标本分布

目的 了解我院ESBLs菌株中TEM型基因携带状况及其标本分布.方法 采用PCR技术300例ESBLs菌株进行扩增,以双纸片协同法检测阴性菌株为对照.结果 300株ESBLs菌株中TEM型基因阳性228株(76%),其中痰液、血液、尿液、分泌物及胆汁分离率为33.3%、17.5%、37.7%、8.3%及3.2%.结论 TEM型ESBLs是ESBLs菌株中主要型别,各种标本中都有较高的分离率.     

表达Tie2基因的单核细胞研究进展

肿瘤血管的生成和发展在肿瘤的生长和恶化过程中起着关键作用。一类表达Tie2基因的单核细胞（TEM）通过一些生长因子和化学信号被募集到肿瘤组织中,旁分泌细胞因子促进肿瘤血管的生成和发展。TEM在促进肿瘤血管形成中起着重要作用,与血管内皮细胞祖细胞（EPC）不同的是,TEM只是在肿瘤的血管生成中起促进作用,但在肿瘤周围临近的正常组织中没有发现其存在,TEM被认为是一类肿瘤组织特异性的细胞。以TEM为载体细胞,通过TEM表达抗肿瘤药物,靶向递送的抗肿瘤药物能够有效的抑制肿瘤的生长和恶化。     

镧盐处理后骨髓基质干细胞内超微结构及镧元素分析

目的:探讨镧离子(La3 )能否进入体外成骨化诱导的骨髓基质干细胞(BMSCs)并对其超微结构与金属成分产生影响。方法:取杂种犬第3代体外成骨化诱导培养的BMSCs,于培养基中分别加5.564×102、5.564、5.564×10-2μg/mlLa3 干预,设无La3 干预对照组。用透射电镜(TEM)、电子探针波谱(EM-WS)及高分辨透射电镜能谱(HRTEM)观察BMSCs超微结构与金属成分。结果:TEM下观察3种浓度La3 作用后BMSCs溶酶体内有电子致密物质存在,对照组无此现象;3组BMSCs的部分细胞器有轻微变性现象,与对照组相似;EMWS检测到5.564×102μg/ml的La3 作用后BMSCs中有镧元素存在;3种浓度La3 作用后HRTEM检测BMSCs内均未测出镧元素。结论:一定浓度下La3 可能进入BMSCs。     

An ultrastructural study of the effects of acidic phospholipid substitutions on calcium phosphate precipitation in anionic liposomes

Summary A model membrane system was used to investigate the ability of specific membrane constituents to modulate the precipitation of calcium phosphate. Intraliposomal precipitation was induced in phosphate-encapsulated liposomes composed of 7:2:1 molar mixtures of phosphatidylcholine (PC), dicetyl phosphate (DCP), and cholesterol (Chol) by ionophore-supported (X-537A) Ca²⁺ uptake. Extraliposomal precipitation occurred when these reactions were initiated in metastable external solutions. In this case, the endogenously formed crystals penetrated through the enclosing lipid bilayers and seeded the external solution phase. Transmission electron microscopy (TEM) was used to monitor the effect of acidic phospholipids [phosphatidic acid (PA), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylglycerol (PG)] on the precipitation reactions when these molecular species were incorporated into the liposome membranes. Compared with the precipitation reactions in 7PC:2DCP:1Chol liposomes containing no acidic phospholipids, calcium phosphate formation in the presence of monoester phosphate (PA) and amino-(PS) phospholipids was inhibited. Analyses of the lipid-mineral interactions in PA-containing (10 mol%) liposomes revealed close physical contact between the small crystals of apatite and the inner lipid bilayers; there was only minimal extraliposomal precipitation. A few small crystals adhered to the external surfaces of the liposomes. In PS-containing liposomes, lipid-mineral interactions were dependent upon the DCP content of the lipid membrane. Discrete clusters of crystals formed within the interior aqueous compartment when intraliposomal precipitation was initiated in 7PC:2DCP:1Chol liposomes doped with up to 10 mol% PS. There was no evidence for specific associations between these crystals and the enclosing lipid bilayers. In contrast, the liposomes clustered around extraliposomally formed crystals, with the lipid membranes adhering tightly to the exposed crystal surfaces. These crystallipid interactions were reversed when the DCP component was omitted from the liposome membrane (7PC:1PS:1Chol liposomes). These results suggest that PS may be localized preferentially on the outer membrane surface in the presence of DCP but concentrated on the inner aspect in its absence. No such interactions were observed in PI or PG-containing liposomes. The liposome-mediated precipitation events were not affected in these preparations. The data suggest that the inhibition of calcium phosphate formation resulted from specific interactions between the nascent crystals and lipid species present in the liposome membrane. The molecular conformation of the head group, the molecular geometry of the phospholipids in the membrane, and the relative affinity of the incorporated species for Ca²⁺ were key determinats of these interactions.     

Complementary use of local excision and transanal endoscopic microsurgery for rectal cancer after neoadjuvant chemoradiation

Background Neoadjuvant therapies have significantly improved local control and survival of patients with rectal cancer. Nevertheless, although a complete pathologic response can be achieved in 30% of cases, a transabdominal surgical resection is always required. This study aimed, for the first time, to test in the literature the feasibility of local excision combined with transanal endoscopic microsurgery (TEM) as a surgical option for patients treated with neoadjuvant chemoradiation. Methods Between July 1997 and December 2002, 30 patients with rectal cancer affected by an extraperitoneal tumor entered a protocol consisting of neoadjuvant chemoradiation followed by surgery. The surgical treatment, consisting of open surgery, local excision, or TEM, was planned according to the patient’s clinical response after chemoradiation and distance from the anal verge. Results A significant clinical downstaging was observed in eight patients. Five of these patients underwent TEM, and three had local excision. Consequently, open surgery was performed for 22 patients. Histology showed six cases of complete pathologic response: three in the open surgery group and three in the transanal excision group. After a mean follow-up period of 47 months, the disease-free survival rate was 77% in the open surgery group and 100% in TEM or local excision group. Conclusions The findings suggest the complementary feasibility of TEM and local excision after neoadjuvant chemoradiation. However, randomized trials are needed to confirm the oncologic safety of this approach.     

Athermal ω Phase and Lattice Modulation in Binary Zr-Nb Alloys

To further explore the potential of Zr-based alloys as a biomaterial that will not interfere with magnetic resonance imaging (MRI), the microstructural characteristics of Zr-xat.% Nb alloys (10 ≤ x ≤ 18), particularly the athermal ω phase and lattice modulation, were investigated by conducting electrical resistivity and magnetic susceptibility measurements and transmission electron microscopy observations. The 10 Nb alloy and 12 Nb alloys had a positive temperature coefficient of electrical resistivity. The athermal ω phase existed in 10 Nb and 12 Nb alloys at room temperature. Alternatively, the 14 Nb and 18 Nb alloys had an anomalous negative temperature coefficient of the resistivity. The selected area diffraction pattern of the 14 Nb alloy revealed the co-occurrence of ω phase diffraction and diffuse satellites. These diffuse satellites were represented by g_β + q when the zone axis was [001] or [113], but not [110]. These results imply that these diffuse satellites appeared because the transverse waves consistent with the propagation and displacement vectors were q = <ζ ζ¯ 0>* for the ζ~1/2 and <110> directions. It is possible that the resistivity anomaly was caused by the formation of the athermal ω phase and transverse wave. Moreover, control of the athermal ω-phase transformation and occurrence of lattice modulation led to reduced magnetic susceptibility, superior deformation properties, and a low Young’s modulus in the Zr-Nb alloys. Thus, Zr-Nb alloys are promising MRI-compatible metallic biomaterials.     

Platelet-rich plasma with keratinocytes and fibroblasts enhance healing of full-thickness wounds

Advances in tissue engineering led to the development of various tissue-engineered skin substitutes (TESS) for the treatment of skin injuries. The majority of the autologous TESS required lengthy and costly cell expansion process to fabricate. In this study, we determine the possibility of using a low density of human skin cells suspended in platelet-rich plasma (PRP)-enriched medium to promote the healing of full-thickness skin wounds. To achieve this, full-thickness wounds of size 1.767 cm² were created at the dorsum part of nude mice and treated with keratinocytes (2 × 10⁴ cells/cm²) and fibroblasts (3 × 10⁴ cells/cm²) suspended in 10% PRP-enriched medium. Wound examination was conducted weekly and the animals were euthanized after 2 weeks. Gross examination showed that re-epithelialization was fastest in the PRP+cells group at both day 7 and 14, followed by the PRP group and NT group receiving no treatment. Only the PRP+cells group achieved complete wound closure by 2 weeks. Epidermal layer was presence in the central region of the wound of the PRP+cells and PRP groups but absence in the NT group. Comparison between the PRP+cells and PRP groups showed that the PRP+cells-treated wound was more mature as indicated by the presence of thinner epidermis with single cell layer thick basal keratinocytes and less cellular dermis. In summary, the combination of low cell density and diluted PRP creates a synergistic effect which expedites the healing of full-thickness wounds. This combination has the potential to be developed as a rapid wound therapy via the direct application of freshly harvested skin cells in diluted PRP.     

Anthrax toxin triggers the activation of src-like kinases to mediate its own uptake

AB-type toxins, like other bacterial toxins, are notably opportunistic molecules. They rely on target cell receptors to reach the appropriate location within the target cell where translocation of their enzymatic subunits occurs. The anthrax toxin, however, times its own uptake, suggesting that toxin binding triggers specific signaling events. Here we show that the anthrax toxin triggers tyrosine phosphorylation of its own receptors, capillary morphogenesis gene 2 and tumor endothelial marker 8, which are not endowed with intrinsic kinase activity. This is required for efficient toxin uptake because endocytosis of the mutant receptor lacking the cytoplasmic tyrosine residues is strongly delayed. Phosphorylation of the receptors was dependent on src-like kinases, which where activated upon toxin binding. Importantly, src-dependent phosphorylation of the receptor was required for its subsequent ubiquitination, which in turn was required for clathrin-mediated endocytosis. Consistently, we found that uptake of the anthrax toxin and processing of the lethal factor substrate MEK1 are inhibited by silencing of src and fyn, as well as in src and fyn knockout cells.