含银介孔二氧化硅-壳聚糖复合材料的制备与性能研究

目的探讨含银介孔二氧化硅-壳聚糖复合材料(Ag/MSN-Chi)的制备方法及其微观表征、细胞毒性、吸水性能、抗菌性能及止血性能。 方法以正硅酸乙酯为前驱体，十六烷基三甲基溴化铵为致孔剂，采用离子交换法在介孔二氧化硅纳米粒子(MSN)中引入银离子，制备出具有抗菌作用的新型有序的含银介孔二氧化硅纳米粒子(Ag/MSN)材料。再利用烷基化壳聚糖负载Ag/MSN，制备出Ag/MSN-Chi。根据所用材料不同将实验分为实验组和空白对照组，实验组又分为3个亚组：MSN组、Ag/MSN组、Ag/MSN-Chi组，空白组为不加任何材料的阳性对照。计算MSN和Ag/MSN的比表面积、孔容、孔径和Ag/MSN与Ag/MSN-Chi的电荷。并通过吸水实验、体外凝血实验、抗菌实验对MSN、Ag/MSN和Ag/MSN-Chi的细胞毒性、吸水性能、止血性能及抗菌性能进行评价，计算细胞相对存活率、吸水率、凝血酶原时间(PT)、凝血活酶时间(APTT)及抑菌率。取健康成年新西兰大白兔18只，随机分成3组：对照组(采用医用纱布处理)、Ag/MSN组(采用Ag/MSN处理)、Ag/MSN-Chi组(采用Ag/MSN-Chi处理)，每组6只，建立肝创伤出血模型，计算止血时间。数据比较采用方差分析和t检验。 结果MSN的比表面积为(523.8±12.4) m²/g、孔容为(1.2±0.4) m³/g、孔径为(3.5±0.9) nm；Ag/MSN的比表面积为(521.6±11.7) m²/g、孔容为(1.15±0.5) m³/g、孔径为(3.6±0.7) nm，2种材料的比表面积、孔容、孔径比较差异均无统计学意义(t＝0.224、0.135、0.015，P值均大于0.05)。经测量，Ag/MSN的Zeta电位为－19.7 mV，Ag/MSN-Chi的Zeta电位为10.27 mV，表明Ag/MSN表面电荷从负值变为正值。Ag/MSN-Chi组、Ag/MSN组和MSN组与小鼠成肌细胞共培养1、4、7 d的细胞相对存活率比较，差异均无统计学意义(F＝2.61、4.72、3.52, P值均大于0.05)。Ag/MSN组吸水率分别与MSN组和Ag/MSN-Chi组比较，差异均无统计学意义(t＝0.482、1.159，P值均大于0.05)。经检测，Ag/MSN-Chi组、Ag/MSN组、MSN组和空白对照组的PT比较，差异无统计学意义(F＝10.28，P>0.05)；Ag/MSN-Chi组、Ag/MSN组、MSN组和空白对照组APTT分别为(20.9±2.1)、(28.5±3.4)、(31.4±2.6)、(38.7±2.5) s，4组比较差异有统计学意义(F＝8.70，P<0.05)；Ag/MSN-Chi组、Ag/MSN组、MSN组APTT分别与空白对照组比较，差异均有统计学意义(t＝9.443、4.186、3.506，P值均小于0.05)；Ag/MSN-Chi组APTT与Ag/MSN组比较，差异有统计学意义(t＝3.294，P<0.05)。MSN组在培养0.5、2、4、6、24 h 5个时间点抑菌率比较差异无统计学意义(F＝5.437，P>0.05)；培养0.5 h，Ag/MSN组和Ag/MSN-Chi组抑菌率分别为(99.7±5.2)%、(97.1±5.4)%，与培养0.5 h MSN组抑菌率(11.2±5.8)%比较，差异均有统计学意义(t＝19.678、18.775, P值均小于0.05)；培养24 h，Ag/MSN组和Ag/MSN-Chi组抑菌率分别为(73.2±5.1)%和(72.9±6.9)%，与MSN组(11.8±5.7)%比较，差异均有统计学意义(t＝13.904、11.825, P值均小于0.05)。Ag/MSN-Chi组、Ag/MSN组和对照组止血时间分别为(12.3±1.5)、(17.2±3.4)、(28.1±3.8) s，3组比较差异有统计学意义(F＝5.892，P<0.05)；Ag/MSN-Chi组和Ag/MSN组止血时间分别与对照组比较，差异均有统计学意义(t＝9.473、5.236, P值均小于0.05)；且Ag/MSN-Chi组与Ag/MSN组止血时间比较，差异有统计学意义(t＝3.230，P<0.05)。 结论Ag/MSN-Chi在不增加细胞毒性的基础上具有有较好的吸水性能、止血性能及抗菌性能。     

An improved method for utilization of peptide substrates for antibody characterization and enzymatic assays

Synthetic peptides have become an important tool in antibody production and enzyme characterization. The small size of peptides, however, has hindered their use in assays systems, such as Western blots, and as immunogens. Here, we present a facile method to improve the properties of peptides for multiple applications by ligating the peptides to intein-generated carrier proteins. The stoichiometric ligation of peptide and carrier achieved by intein-mediated protein ligation (IPL) results in the ligation product migrating as a single band on a SDS-PAGE gel. The carrier proteins, HhaI methylase (M.HhaI) and maltose-binding protein (MBP), were ligated to various peptides; the ligated carrier-peptide products gave sharp, reproducible bands when used as positive controls for antibodies raised against the same peptides during Western blot analysis. We further show that ligation of the peptide antigens to a different thioester-tagged carrier protein, paramyosin, produced immunogens for the production of antisera in rabbits or mice. Furthermore, we demonstrate the generation of a substrate for enzymatic assays by ligating a peptide containing the phosphorylation site for Abl protein tyrosine kinase to a carrier protein. This carrier-peptide protein was used as a kinase substrate that could easily be tested for phosphorylation using a phosphotyrosine antibody in Western blot analysis. These techniques do not require sophisticated equipment, reagents, or skills thereby providing a simple method for research and development.     

Defective Treg response in acute kidney injury was caused by a reduction in TIM-3+ Treg cells

Background: Despite years of research, the treatment of acute kidney injury (AKI) remains a significant challenge. Animal studies presented causal links between elevated regulatory T cell (Treg) response and better prognosis in AKI. Previous studies in mice and humans showed that TIM-3+ Treg cells were more potent than TIM-3- Treg cells. In this study, we investigated the role of TIM-3 in Treg in AKI patients.

Methods: Peripheral blood from AKI patients and healthy controls were gathered, and TIM-3+ Treg subset was examined.

Results: Compared to healthy controls, the AKI patients presented a significant upregulation in the frequency of circulating CD4+CD25+ T cells; however, the majority of this increase was from the CD4+CD25+TIM-3- subset, and the frequency of CD4+CD25+TIM-3+ T cells was downregulated in AKI patients. In both healthy controls and AKI patients, the CD4+CD25+TIM-3+ T cells expressed higher levels of Foxp3, and were more potent at expressing LFA-1, LAG-3, CTLA-4, IL-10 and TGF-β. In addition, the CD4+CD25+TIM-3+ T cells from both healthy controls and AKI patients presented higher capacity to suppress CD4+CD25- T cell proliferation than the CD4+CD25+TIM-3- T cells. Interestingly, the total CD4+CD25+ T cells from AKI patients presented significantly lower inhibitory capacity than those from healthy controls, indicating that the low frequency of CD4+CD25+TIM-3+ T cells was restricting the efficacy of the Treg responses in AKI patients.

Conclusions: We demonstrated that TIM-3 downregulation impaired the function of Treg cells in AKI. The therapeutic potential of CD4+CD25+TIM-3+ T cells in AKI should be investigated in future studies.     

The effects of tibial rotation on patellar position

The effects of external and internal tibial rotation on patellar motion were investigated using a magnetic 3Space^® tracker system (Polhemus, Colchester, VT 05446, USA). Seven fresh-frozen adult cadaver knees were used in this study. The muscle alignment of each quadriceps muscle was measured to determine the direction of loading forces. Three loading patterns were used to simulate the unresisted knee extension during sitting, standing from squatting and the stance phase of walking, with different weights applied to each quadriceps muscle at each knee flexion angle. The position of the patella, along with patellar shift, tilt and rotation was measured and compared to external or internal tibial rotation and neutral rotation. In the sitting and squatting simulations the patella showed at the terminal extension of the knee more lateral shift and a more lateral tilt with tibial external rotation than in a neutral position (P < 0.05). In walking simulation, the patella showed more external rotation with external rotation of the tibia than with a neutral one, at the 0, 72 and 90% of the stance phase of walking (P < 0.05). These results demonstrate the importance of external tibial rotation as a factor in the development of patellar dislocations or subluxations, especially in athletes.     

妊高征患者淋巴细胞β_2－肾上腺素能受体结合量改变及与新生儿体重关系的研究

应用放射配体结合分析，测定４０例正常晚期妊娠妇女及４０例妊高征妇女外周血淋巴细胞β_２－肾上腺素能受体（β_２－ＡＲ）结合量，并测定两组妇女分娩的新生儿体重。结果为：１．正常晚期妊娠妇女外周淋巴细胞β_２－ＡＲ结合量明显降低，妊高征妇女β_２－ＡＲ结合量降低更显著；２．妊高征孕妇组的新生儿出生体重明显低于正常妊娠组的新生儿体重；３．孕妇β_２－ＡＲ结合量与新生儿出生体重呈明显正相关，提示好高征与机体β_２－ＡＲ结合量下降有关，β_２－ＡＲ改变影响胎儿生长发育。     

Monocyte chemotactic protein-3 (MCP3) interacts with multiple leukocyte receptors: binding and signaling of MCP3 through shared as well as unique receptors on monocytes and neutrophils

The diversity of monocyte chemotactic protein (MCP)3 target cell types, as well as the capacity of MCP3 to desensitize leukocyte responses to other CC chemokines, suggested that MCP3 may interact with multiple CC chemokine receptors. The purpose of this study is to establish how MCP3 binds and activates monocytes and neutrophils. We show that human monocytes exhibit high-affinity binding for ¹²⁵I-MCP3 with an estimated Kd of 1–3 nM and about 10000 binding sites/cell. The binding of ¹²⁵I-MCP3 to monocytes was progressively less well competed by CC chemokines macrophage inflammatory protein (MIP)lα (Kd = 5–10 nM), RANTES (Kd = 5–10 nM), MCP1 (monocyte chemoattractant and activating factor, or MCAF) (Kd = 60 nM) and MIP1β (Kd > 100 nM). On the other hand, unlabeled MCP3 displaced the binding of radiolabeled MIP1α, RANTES, MCP1 and MIP1β as effectively as the isologous CC chemokines. In agreement with the binding data, pretreatment of monocytes with MCP3 completely desensitized the calcium flux in response to MIP1α and RANTES. However, MIP1α and RANTES failed to desensitize the response of monocytes to MCP3. MCP3 and MCP1 partially desensitized each other's effects on monocytes. These binding and cross-desensitization results suggest that MCP3 binds and signals through other binding sites in addition to those shared with MIP1α, RANTES and MCP1. The unidirectional competition for MIP1β binding and signaling by MCP3 suggests the existence of an as-yet unidentified site for MCP3 shared with MIP1β. The existence of another unique binding site(s) for MCP3 was further shown by the failure of any of the other CC chemokines to compete effectively for MCP3 binding on neutrophils. MCP3 in our study was also the only human CC chemokine that consistently chemoattracted neutrophils. These results suggest that MCP3 is a ligand that can bind and activate a broad range of target cells through receptors shared by other CC chemokines as well as its own receptor.     

Identification of testis development and spermatogenesis-related genes in human and mouse testes using cDNA arrays

We have constructed cDNA microarrays from the human testis large insert cDNA library, containing 9216 genes, together with several housekeeping genes. The cDNA microarrays were used to identify gene expression differences between human fetal and adult testes. Of >8700 hybridized clones, 731 exhibited significant differential expression characteristics. About 7500 genes were identified when the same cDNA microarrays were used for hybridization with cDNA probes from mouse testis, with 256 genes having significant differential expression between the age of 1-4 weeks. Among these genes, 101 were identified as critically related to testis development and possibly to spermatogenesis since they were found in both human and mouse testes, and expressed differentially at different stages of testis development. Of the 101 development-related genes, 59 full-length cDNAs have been sequenced previously, while the full-length cDNAs of the other 42 genes have not been published. We have obtained 11 full-length sequences of the 42 genes and deposited them in the GenBank. The conserved testis development-related genes found in both human and mouse testes may include genes that are likely to be involved in testicular functions, especially spermatogenesis, thus providing a basis for further functional characterization of the genes in mouse models.     

Functional magnetic resonance imaging evidence for binocular interactions in human visual cortex

Using functional magnetic resonance imaging (fMRI), we explored the binocular interactions occurring when subjects viewed dichoptically presented checkerboard stimuli. A flickering radial checkerboard was presented to each eye of the subject, while T2*-weighted images were acquired over the visual cortex with gradient-echo, echoplanar sequences. We compared responses in striate and extrastriate visual cortex under four conditions: both eyes were stimulated at the same time (binocular condition), each eye was stimulated in alternation (monocular condition) or first the one eye then the other eye was stimulated (left eye first - right eye trailing, or vice versa). The results indicate that only the striate area, in and near the calcarine fissure, shows significant differences for these stimulation conditions. These differences are not evident in more remote extrastriate or associational visual areas, although the BOLD response in the stimulation-rest comparison was robust. These results suggest that the effect could be related to inhibitory interactions across ocular dominance columns in striate visual cortex.     

An electrical admittance based index of thoracic intracellular water during head-up tilt in humans

During 50 degrees head-up tilt (HUT), the number of erythrocytes within the thorax has been shown to be reduced by approximately 25% and this level is retained during a maintained tilt, whilst that in the thigh increases by approximately 70%. To evaluate whether the electrical admittance of intracellular water (ICW) may be used to monitor this redistribution of red cells in humans, we determined the regional difference in the reciprocal value of the impedance at 1.5 and 100 kHz for the thorax (thoraxICW) and for the leg (legICW). In ten subjects all variables remained unchanged during head-down tilt but during HUT, presyncopal symptoms were induced in eight subjects after a mean of 27 (SEM 7) min as mean heart rate dropped from 85 (SEM 4) to 66 (SEM 3) beats x min(-1), mean arterial blood pressure from 80 (SEM 3) to 60 (SEM 5) mmHg, and mean oxygen saturation of venous blood from 76 (SEM 2)% to 73 (SEM 3)% (P < 0.05). The mean haematocrit increased from 50 (SEM 5)% to 52.5 (SEM 3.5)% (P < 0.01) and mean central venous pressure decreased during tilting (from a mean of 1 (SEM 1) to a mean of -1 (SEM 1) mmHg; P < 0.05) and returned to value at rest during the maintained tilt. Mean thoracic impedances increased by 7.0 (SEM 1.0) ohms (1.5 kHz) and 5.4 (SEM 1.2) ohms (100 kHz), and mean leg impedances decreased by 9.3 (SEM 1.2) ohms (1.5 kHz) and 3.1 (SEM 1.0) ohms (100 kHz) (P < 0.01). Mean thoraxICW decreased at 40 degrees HUT and remained reduced by 11 (SEM 2) S x 10(-4) (P < 0.05) until the presyncopal symptoms developed, at which time it was lower by 16 (SEM 2) S x 10(-4) (P < 0.01). Mean legICW increased from 97 (SEM 15) to 99 (SEM 15) S x 10(-4) (P = 0.08) during HUT but decreased during maintained tilt (to 94 (SEM 15) S x 10(-4); P < 0.05). The results suggested that during HUT, the difference in electrical admittance at a high and a low frequency current reflects the reduced number of red cells within the thorax.     

汉族男子体格及生殖器发育特点

2411例汉族男性大学生体格和生殖器的测量结果如下:阴茎周径8.17±0.64cm,阴茎长度7.43±1.04cm,阴茎牵长13.33±1.19cm,右睾丸容积17.91±4.09ml,左睾丸容积17.83±4.05ml,身高171.07±5.66cm,体重58.43±7.75kg.北方学生体格和生殖器发育均优于南方.城、县、乡学生的生殖器发育无明显差异,但城市学生体格发育优于农村.16岁后阴茎、睾丸大小变化不大,但生殖器的发育可持续到30岁.