Mouse embryonic diastema region is an ideal site for the development of ectopically transplanted tooth germ.

The anterior eye chamber and the kidney capsule of the mouse have been traditionally used for long-term culture of tooth germ grafts. However, although these sites provide an excellent growth environment, they do not represent real in situ sites for the development of a grafted tooth germ. Here, we describe a protocol to transplant a tooth germ into the mandibular diastema region of mouse embryos using exo utero surgery. Our results demonstrate that the mouse embryonic diastema region represents a normal physiological environment for the development of transplanted tooth germs. Transplanted tooth germs developed synchronically with and became indistinguishable from the endogenous ones. These ectopic teeth were vascularized and surrounded with nerve fibers, and were able to erupt normally. Thus, the exo utero transplantation approach will provide a new avenue to study tooth development and regeneration.     

Dynamic imaging of the lungs using x-ray phase contrast

High quality real-time imaging of lungs in vivo presents considerable challenges. We demonstrate here that phase contrast x-ray imaging is capable of dynamically imaging the lungs. It retains many of the advantages of simple x-ray imaging, whilst also being able to map weakly absorbing soft tissues based on refractive index differences. Preliminary results reported herein show that this novel imaging technique can identify and locate airway liquid and allows lung aeration in newborn rabbit pups to be dynamically visualized.     

HIV－1Protease在大肠杆菌中的高表达

艾滋病的致病因子为人免疫缺陷病毒。该病毒的蛋白酶在病毒复制和成熟中具有决定性的意义。由于目前国内外尚未获得艾滋病病毒蛋白酶高效表达的重组子及简便的活性检测系统，限制了它的研究与应用。本文将用ＰＣＲ技术修饰的ＨＩＶＰｒ基因克隆入原核高效表达载体ｐＴＴＱ１８的ＥｃｏＲⅠ和ＨｉｎｄⅢ酶切位点之间，并用豆芽核酸酶将ＥｃｏＲⅠ的粘端削平，构建了读框正确的表达载体，ＩＰＴＧ诱导表明，该重组子在大肠杆菌中获得了高表达，激光扫描结果表明：重组的ＨＩＶＰｒ占细菌总蛋白８．９％以上。     

Clinical experiences of bacteremia caused by metallo-beta-lactamase-producing gram-negative organisms.

The emergence of acquired metallo-beta-lactamase (MBL) in gram-negative bacilli is regarded as a therapeutic challenge since such enzymes are capable of hydrolyzing all beta-lactams in vitro except the monobactams. The clinical characteristics and outcome of 8 episodes of gram-negative bacteremia caused by MBL-producing isolates from January 1997 through December 2000 (Klebsiella pneumoniae, 6 isolates; Pseudomonas stutzeri, 4; Pseudomonas aeruginosa, 1; and Pseudomonas putida, 1) were analyzed. The median age of the patients was 61 years (range, 2-95 years). Most patients (n = 6, 75%) had more than 1 comorbid illness or condition and 6 patients acquired bacteremia in the intensive care unit. The median time from admission to the first positive culture was 34.5 days (range, 1-99 days). Pneumonia was the most common site of infection. Five patients (62.5%) received a carbapenem to treat bacteremia. The median time to defervescence was 6 days (range, 2-12 days). No bacteriologic failure was noted during or after antimicrobial therapy. The overall mortality rate from bacteremia caused by gram-negative, MBL-producing organisms was nil at 14 or 28 days.     

Absence of Epstein-Barr virus (EBV) in intrahepatic cholangiocarcinoma confirmed by lack of EBV-coded nuclear RNA and latent membrane protein-1

AIMS: Studies are disclosing that Epstein-Barr virus (EBV) is involved in the aetiology of various neoplasms including undifferentiated carcinomas of the aerodigestive tract. The aetiology of intrahepatic cholangiocarcinoma (ICC), a malignant neoplasm arising from intrahepatic biliary epithelia, has yet to be fully evaluated. To date, two cases of EBV-related ICC have been reported, and they presented foci of lymphoepitheliomatous undifferentiated carcinoma components. METHODS AND RESULTS: To determine whether EBV is commonly involved in the developments of ICC, we performed in-situ hybridization and immunohistochemistry for EBV in 215 cases of ICC in Japan, using a probe against EBV-coded nuclear RNA (EBER) and a specific antibody against latent membrane protein-1 (LMP-1), respectively. We did not detect EBV-infected carcinoma cells in any of the ICC cases examined. No lymphoepitheliomatous undifferentiated carcinoma components were found either. CONCLUSION: The results suggest that EBV infection is unlikely to be involved in the pathogenesis of ICC.     

盲人智能探路手杖的研究

本文介绍了盲人智能探路手杖的研究.该系统由单片机控制,采用两只超声波传感器的探测模式,对盲人行进路上的路况进行探测和分析,并针对不同的路况发出相应的提示信息,以达到辅助盲人安全行走的目的.     

Cloning and spatial and temporal expression of the zebrafish dopamine D1 receptor.

Dopamine plays important roles in the regulation of central nervous system (CNS) development and functions. In vertebrates, two families of dopamine receptors, collectively known as dopamine D1 and D2 receptors, have been identified. Recently, dopamine receptors have been targeted by pharmacological and therapeutic studies of neurological disorders, such as Parkinson's disease. Here, we report a study on the molecular characterization of dopamine D1 receptor in zebrafish (Danio rerio). We cloned the full-length cDNA of a zebrafish dopamine D1 receptor, designated as drd1. The sequence of drd1 shares high homology to the sequences of dopamine D1 receptors in mammalian, amphibian, and other fish species. drd1 is expressed in the CNS. The first drd1 expression was observed at approximately 30 hours postfertilization, at which time the expression was seen in the developing diencephalon and hindbrain. In developing retinas, the expression of drd1 was detected in the inner nuclear layer with the exception of the marginal zones. In adult retinas, drd1 expression was detected in most cell types in the inner and outer nuclear layers as well as ganglion cell layer. Differential expression of drd1 in developing and adult retinas may play various roles in regulating visual system functions.     

钙池操纵的钙通道的调控机制

钙池操纵的钙通道(store-operated calciumchannel,SOC)系存在于细胞膜表面的一种新发现的钙通道,它是非兴奋性细胞Ca2 内流的主要通道。SOC的开启是由钙库耗竭所激发,然而,钙库耗竭如何开启SOC仍不十分清楚。文章综述了SOC开启调控机制的有关研究进展。     

磷酸组织胺诱导的Ⅰ型超敏反应对肝损伤作用的研究

目的:通过观察与Ⅰ型超敏反应相关的生物活性介质--组织胺对家兔肝脏有无直接损伤作用,进一步论证Ⅰ型超敏反应对肝脏的损伤作用.方法:选择34只家兔随机分为对照组、实验Ⅰ组和实验Ⅱ组3组;对照组只进行正常饲料喂养,实验Ⅰ组在正常饲料喂养的同时每天给予0.4μg/kg耳静脉注射磷酸组胺注射液,实验Ⅱ组在正常饲料喂养的同时每天给予0.08 μg/kg耳静脉注射磷酸组胺注射液;动态观察以上3个组的血清谷丙转氨酶(ALT)及血清谷草转氨酶(AST)变化;利用光学显微镜观察以上3个组肝组织的病理变化.结果:无论是实验Ⅰ组或实验Ⅱ组,经过一段时间的观察,发现血清内ALT和AST含量均显着高于对照组(P＜0.01),但Ⅰ、Ⅱ组之间无显着性差异(P＞0.05);实验Ⅰ组和实验Ⅱ组在显微镜下观察,其肝脏均有不同程的损伤和病理改变,且实验Ⅱ组的损伤和变化大于实验Ⅰ组,而对照组的肝脏则无明显的病理变化.结论:组织胺对家兔肝脏确实有一定的损伤作用,而且随着投予剂量和时间的增加,肝脏的损伤和病理变化也越显著;通过本研究,可以得出Ⅰ型超敏反应导致肝脏病理变化及损伤的见解.     

Plasmids encoding foot-and-mouth disease virus VP1 epitopes elicited immune responses in mice and swine and protected swine against viral infection

VP1 is a capsid protein of foot-and-mouth disease virus (FMDV) and contains epitopes of the virus. Plasmids encoding two VP1 epitopes (amino acid residues 141-160 and 200-213) and a host-self immunoglobulin molecule were constructed to produce a new type of FMD DNA vaccine. Two plasmids, namely, pCEIM and pCEIS, containing mouse immunoglobulin (IgG) or swine IgG were subjected to immunogenicity testing in mice and swine, respectively. In mice administrated pCEIM in the abdomen using a genegun, both FMDV-specific T-cell proliferation and neutralizing antibodies were detected. In swine immunized with pCEIS at the back of the ear, immune responses were achieved after the second administration. Swine showed a T-cell proliferative response with a stimulation index (SI) of up to 8.1 and a neutralizing antibody response that was able to protect suckling mice from 10(2) LD(50) (lethal dose 50) FMDV challenge. To compare the immunogenicity of the DNA-based vaccine candidate, versus the protein-based vaccine candidates, a second group of swine was immunized with the protein F1-scIgG, which was encoded by the plasmid pCEIS. Injection with F1-scIgG elicited a T-cell proliferative response of SI < 1.7 and a neutralizing antibody response that protected suckling mice from up to 10(5) LD(50) FMDV challenge. In the challenge test, three of three swine immunized with pCEIS were fully protected from FMDV challenge.