小鼠肠腺瘤类器官培养及其辐射敏感性

目的 建立小鼠肠腺瘤类器官的体外培养方法,观察其对电离辐射的反应。方法 采用氧化偶氮甲烷(azoxymethane,AOM)和葡聚糖硫酸钠(detrain sodium sulfate,DSS)诱导小鼠产生肠腺瘤。体外分离腺瘤类隐窝结构,接种于基质胶。通过培养基筛选,确定肠腺瘤类器官的体外培养条件,采用免疫组化染色检测Ki67和β-catenin表达水平。进一步采用X线照射,观察肠腺瘤类器官损伤情况,比较其与大、小肠类器官的辐射敏感性。 结果 经AOM/DSS诱导,小鼠肠腺瘤成瘤率达95%,肿瘤均位于结肠靠近直肠处,肠腺瘤类器官在改良的小肠类器官中生长良好,Ki67阳性腺瘤细胞比例高且β-catenin入核特征明显。经X线照射,各类器官存活比例随辐射剂量增加而降低。9 Gy照射7天后,腺瘤类器官存活率为11.96%±1.42%,高于同剂量大肠类器官的5.46%±1.22% (t=6.0082,P＜0.01),小肠类器官几乎未见存活。腺瘤类器官剂量存活曲线较大、小肠类器官右移,提示其辐射敏感性低于大肠和小肠。 结论 在AOM/DSS诱导产生的小鼠肠腺瘤中成功分离培养出腺瘤类器官,其辐射敏感性低于大、小肠类器官。     

Protein-Bound Uremic Toxins: New Culprits of Cardiovascular Events in Chronic Kidney Disease Patients

Chronic kidney disease (CKD) has been considered a major risk factor for cardiovascular diseases. Although great advances have recently been made in the pathophysiology and treatment of cardiovascular diseases, CKD remains a major global health problem. Moreover, the occurrence rates of cardiovascular events among CKD patients increase even in cases in which patients undergo hemodialysis, and the mechanisms underlying the so-called “cardiorenal syndrome” are not clearly understood. Recently, small-molecule uremic toxins have been associated with cardiovascular mortality in CKD and/or dialysis patients. These toxins range from small uncharged solutes to large protein-bound structures. In this review, we focused on protein-bound uremic toxins, such as indoxyl sulfate and p-cresyl sulfate, which are poorly removed by current dialysis techniques. Several studies have demonstrated that protein-bound uremic toxins, especially indoxyl sulfate, induce vascular inflammation, endothelial dysfunction, and vascular calcification, which may explain the relatively poor prognosis of CKD and dialysis patients. The aim of this review is to provide novel insights into the effects of indoxyl sulfate and p-cresyl sulfate on the pathogenesis of atherosclerosis.     

Biocompatibility evaluation of dicalcium phosphate/calcium sulfate/poly (amino acid) composite for orthopedic tissue engineering in vitro and in vivo

In vitro cytocompatibility of ternary biocomposite of dicalcium phosphate (DCP) and calcium sulfate (CS) containing 40 wt% poly (amino acid) (PAA) was evaluated using L929 ?broblasts and MG-63 osteoblast-like cells. Thereafter, the biocompatibility of biocomposite in vivo was investigated using an implantation in muscle and bone model. In vitro L929 and MG-63 cell culture experiments showed that the composite and PAA polymer were noncytotoxic and allowed cells to adhere and proliferate. The scanning electron microscope (SEM) confirmed that two kinds of cells maintained their phenotype on all of samples surfaces. Moreover, the DCP/CS/PAA composite showed higher cellular viability than that of PAA; meanwhile, the cell proliferation and ALP activity were much higher when DCP/CS had added into PAA. After implanted in muscle of rabbits for 12 weeks, the histological evaluation indicated that the composite exhibited excellent biocompatibility and no inflammatory responses were found. When implanted into bone defects of femoral condyle of rabbits, the composite was combined directly with the host bone tissue without fibrous capsule tissue, which shown good biocompatibility and osteoconductivity. Thus, this novel composite may have potential application in the clinical setting.     

Ultrathin films of charged polysaccharides assembled alternately with linear polyions

As a means of preparation of biocompatible molecular surfaces, an alternate assembly of charged polysaccharides and oppositely-charged synthetic polymers was conducted. Cationic chitosan was assembled alternately with anionic poly(sodium styrenesulfonate) (PSS) at pH 4. Regular film growth and its dependence on ionic strength were detected by the quartz crystal microbalance (QCM) method. Averaged film thicknesses for the chitosanCPSS layer were 15, 31, 46, and 69 A° , respectively, when 0, 0.25, 0.5, and 1 M of NaCl was contained in aqueous chitosan. Adsorption of chitosan did not reach saturation in 20 min at 0 M NaCl, while the adsorption became saturated within 6 min with 0.25 M NaCl. Anionic sodium chondroitin sulfate was also assembled in alternation with cationic poly(dimethyldiallylammonium chloride) (PDDA) at pH 6.5. The adsorption of chondroitin sulfate was less sensitive to ionic strength. Surface morphology of chitosan–PSS films was investigated by non-contact atomic force microscopy (AFM) observation. Maximum height difference and Ra value for a 1000 × 1000 nm area were 11 and 0.69 nm, respectively, indicating the formation of a molecularly flat surface by alternate layer-by-layer adsorption.     

A bilayer scaffold prepared from collagen and carboxymethyl cellulose for skin tissue engineering applications

Abstract

Treatment of chronic skin wound such as diabetic ulcers, burns, pressure wounds are challenging problems in the medical area. The aim of this study was to design a bilayer skin equivalent mimicking the natural one to be used as a tissue engineered skin graft for use in the treatments of problematic wounds, and also as a model to be used in research related to skin, such as determination of the efficacy of transdermal bioactive agents on skin cells and treatment of acute skin damages that require immediate response. In this study, the top two layers of the skin were mimicked by producing a multilayer construct combining two different porous polymeric scaffolds: as the dermis layer a sodium carboxymethyl cellulose (NaCMC) hydrogel on which fibroblasts were added, and as the epidermis layer collagen (Coll) or chondroitin sulfate-incorporated collagen (CollCS) on which keratinocytes were added. The bilayer construct was designed to allow cross-talk between the two cell populations in the subsequent layers and achieves paracrine signalling. It had interconnected porosity, high water content, appropriate stability and elastic moduli. Expression of vascular endothelial growth factor (VEGF), basic-fibroblast growth factor (bFGF) and Interleukin 8 (IL-8), and the production of collagen I, collagen III, laminin and transglutaminase supported the attachment and proliferation of cells on both layers of the construct. Attachment and proliferation of fibroblasts on NaCMC were lower compared to performance of keratinocyte on collagen where keratinocytes created a dense and a stratified layer similar to epidermis. The resulting constructs succesfully mimicked in vitro the natural skin tissue. They are promising as grafts for use in the treatment of deep wounds and also as models for the study of the efficacy of bioactive agents on the skin.     

Chemical,Mechanical, and Durability Properties of Concrete with Local Mineral Admixtures under Sulfate Environment in Northwest China

Over the vast Northwest China, arid desert contains high concentrations of sulfate, chloride, and other chemicals in the ground water, which poses serious challenges to infrastructure construction that routinely utilizes portland cement concrete. Rapid industrialization in the region has been generating huge amounts of mineral admixtures, such as fly ash and slags from energy and metallurgical industries. These industrial by-products would turn into waste materials if not utilized in time. The present study evaluated the suitability of utilizing local mineral admixtures in significant quantities for producing quality concrete mixtures that can withstand the harsh chemical environment without compromising the essential mechanical properties. Comprehensive chemical, mechanical, and durability tests were conducted in the laboratory to characterize the properties of the local cementitious mineral admixtures, cement mortar and portland cement concrete mixtures containing these admixtures. The results from this study indicated that the sulfate resistance of concrete was effectively improved by adding local class F fly ash and slag, or by applying sulfate resistance cement to the mixtures. It is noteworthy that concrete containing local mineral admixtures exhibited much lower permeability (in terms of chloride ion penetration) than ordinary portland cement concrete while retaining the same mechanical properties; whereas concrete mixtures made with sulfate resistance cement had significantly reduced strength and much increased chloride penetration comparing to the other mixtures. Hence, the use of local mineral admixtures in Northwest China in concrete mixtures would be beneficial to the performance of concrete, as well as to the protection of environment.     

Color change of primary teeth following exposure to an experimentally synthesized liposomal nano-encapsulated ferrous sulfate drop versus the commercially available iron drops

ObjectivesThis study aimed to assess the color change of primary teeth following exposure to an experimentally synthesized liposomal nano-encapsulated ferrous sulfate drop compared with the commercially iron drops.Materials and methodsIn this in-vitro study, liposomal nano-encapsulated ferrous sulfate (lipo-nano-ferr) drop was first synthesized. Next, 110 extracted primary anterior teeth were randomized into two equal groups (sound and demineralized). Each group was randomly divided into 5 subgroups (n = 11) and exposed to Irofant, Feroglobin, Sideral, and lipo-nano-ferr drops for 540 cycles. One subgroup was remained in artificial saliva as the negative control. Tooth color was analyzed before and after the interventions visually, and the rate of iron adsorption was analyzed by atomic absorption spectrometry (AAS), and energy-dispersive X-ray spectroscopy/scanning electron microcopy (EDS/SEM). Data were analyzed using t-test, one-way ANOVA, and LSD test.ResultsIron adsorption was significantly higher by the demineralized specimens than the sound specimens in all subgroups (P < 0.001). A significant difference was noted in iron adsorption among the four subgroups in each of the sound and demineralized groups (P < 0.001). Iron adsorption in the lipo-nano-ferr subgroup was significantly lower than that in Irofant and Feroglobin groups (P < 0.001). The visual inspection results were similar to AAS results. EDS-SEM showed that the atomic percentage of iron in Sideral and lipo-nano-ferr groups was significantly lower than that in Irofant and Feroglobin groups (P < 0.001).ConclusionUse of nano-encapsulation technology in production of iron drops can significantly decrease the resultant tooth discoloration, causing a clinically negligible color change.     

Relaxant effects of metoclopramide and magnesium sulfate on isolated pregnant myometrium: an in vitro study

BackgroundMetoclopramide and magnesium sulfate are extensively used agents in obstetrics. In this study, the relaxant properties of metoclopramide and magnesium sulfate on pregnant myometrium, together with the possible reversing influences of oxytocin and cabergoline (a dopamine D₂ receptor agonist), were investigated.MethodsMyometrial strips from 24 parturients were randomly allocated to four groups: control (Group CON), magnesium sulfate and oxytocin (Group MSO), metoclopramide and oxytocin (Group MEO), and metoclopramide and cabergoline (Group MEC). Myometrial strips were mounted on a myograph bathed in Krebs buffer. Saline (Group CON) and five incremental doses of magnesium sulfate (Group MSO) or metoclopramide (Groups MEO and MEC) were sequentially microinjected into the bath. Subsequently, oxytocin (Groups CON, MSO and MEO) or cabergoline (Group MEC) was microinjected into the bath. The myometrial contractile characteristics after each drug injection, including contractile force, interval and duration, were analyzed.ResultsMagnesium sulfate was more potent for prolonging myometrial contractile interval than reducing contractile force. Metoclopramide relaxed myometrial contractions by inhibiting contractile force and prolonging contractile interval in a concentration-dependent manner. Oxytocin reversed both the inhibited contractile force and the prolonged contractile interval caused by a high concentration of magnesium sulfate but accelerated the contractile interval and had no significant effect on the contractile force suppressed by metoclopramide. The relaxant effects of metoclopramide were completely reversed by cabergoline.ConclusionsBoth magnesium sulfate and metoclopramide relaxed myometrial contractions, and exhibited different responses to subsequent oxytocin treatment. The relaxant mechanism of metoclopramide may be via blockade of dopamine D₂ receptor, which requires further investigation.