兔心窦房结的亚微结构观察

本文观查了8例杂种成免心脏窦房结的亚微结构。窦房结主要由P细胞和T细胞构成。P细胞多成团存在。细胞圆形或多边形,胞核大,可见双核细胞;胞质内肌原纤维和线粒体较少;核糖体、糖原颗粒、高尔基氏器、粗面和滑面内质网均较丰富;高尔基氏器附近有电子密度较高的球形颗粒;胞膜下见到许多小凹和小囊;P细胞间有散在的中间连接。T细胞的形态和结构介于P细胞和心肌细胞之间。最后对窦房结内各细胞的功能特点加以讨论。     

Two cis-acting elements in negative RNA strand of Hepatitis C virus involved in synthesis of positive RNA strand in vitro

Sequences at the 3'-ends of both positive and negative strands of Hepatitis C virus (HCV) RNA harbor cis-acting elements required for RNA replication. However, little is known about the properties of the negative RNA strand as a template for the synthesis of positive RNA strand. In this study, a purified recombinant HCV RNA-dependent RNA polymerase (RdRp) was used to investigate the synthesis of positive RNA strand using the 3'-terminal region of negative RNA strand ((-)3'T RNA) as template. A mutagenesis analysis was performed to evaluate the role of the 3'-proximal stem-loop and the first 3'-cytidylate (3'C) of the negative RNA strand in the synthesis of the positive RNA strand. A negative RNA strand of wild type (wt) HCV as template was able to direct the synthesis of a full-length positive RNA strand. Deletion of the 3'-proximal stem-loop resulted in an approximately 90% decrease in RNA synthesis. Disruption of the 3'-proximal stem-loop structure by nucleotide substitutions led to a 70-80% decrease in RNA synthesis. However, the restoration of the stem-loop by compensatory mutations in the stem region restored also the RNA synthesis. Likewise, the deletion or substitution of the first 3'C by guanylate (G) led to a 90% decrease in the RNA synthesis; while the substitution by adenylate (A) or uridylate (U) resulted in a 60-80% decrease in the RNA synthesis only. These findings demonstrate that the 3'-proximal stem-loop and the first 3'C of the negative RNA strand of HCV are two cis-acting elements involved in the synthesis of the positive RNA strand.     

4种少见脑膜瘤的临床病理观察

报告４种少见的脑膜瘤亚型：分泌型、微囊型、脂肪瘤和黄色瘤型。临床表现主要有头痛、恶心、轻度呕吐、眼底水肿和肢体功能障碍。形态学：分泌型脑膜瘤以散在多个嗜酸性近圆形包含体为特征，包含体对ＣＥＡ、ＥＭＡ呈特异性表达；微囊性脑膜瘤含微小囊腔状如海绵，囊内含粉染浆液，囊壁由疏松和涡漩状排列之瘤细胞组成；脂肪瘤和黄色瘤型脑膜瘤分别在其瘤组织中含有大量脂肪细胞或泡沫细胞为特征。文中讨论了肿瘤形成机制及鉴别要点。     

Ⅱ型糖尿病患者机体脂质过氧化及抗氧化能力研究

测定了Ⅱ型糖尿病患者及健康对照者红细胞超氧化物歧化酶、血中谷胱甘肽过氧化物酶、过氧化氢酶活力及丙二醛（ＭＤＡ）含量。结果：糖尿病患者病程从～１０年组ＳＯＤ活力开始下降，与对照组比较差异有高度显著性（Ｐ＜０．０１），与病程呈高度负相关。ＧＳＨ－Ｐｘ、ＭＤＡ与对照组比较差异均有高度显著性（Ｐ＜０．０１），并与病程呈高度正相关，ＣＡＴ仅１５年以上组与对照组比较差异有显著性（Ｐ＜０．０１），与病程相关不显著（Ｐ＞０．０５）。结果说明，Ⅱ型糖尿病患者脂质过氧化作用增强及抗氧化能力下降，对心血管系统造成氧化性损伤是心血管并发症的重要原因之一。     

Cyclooxygenase-2 mRNA expression is associated with c-fos mRNA expression and transient water ADC reduction detected with diffusion MRI during acute focal ischemia in rats

Cyclooxygenase-2 (COX-2) plays an important role in the development of injury during cerebral ischemia and inhibition of its activity can reduce infarct size. COX-2 expression during acute ischemia is caused by activation of post-synaptic glutamate receptors, which occurs during spreading depression and ischemic depolarization. Both of these phenomena cause a reduction in the apparent diffusion coefficient of water (ADC), which can be detected with diffusion-weighted magnetic resonance imaging. The reduction is believed to be caused by cellular swelling that occurs as cells depolarize. The goal of this work was to determine the spatial relationship between cyclooxygenase-2 mRNA (cox-2) expression, c-fos mRNA expression and ADC reduction during acute focal cerebral ischemia. Adult rats were subjected to either 30- or 60-min permanent occlusion of the middle cerebral artery. A 2-Tesla scanner was used to acquire diffusion-weighted echo-planar images throughout the ischemic period, which were used to calculate ADC maps. Cox-2 and c-fos mRNA were detected with (35)S in situ hybridization. The results indicate that, for rats subjected to 60-min ischemia, cox-2 was observed in superficial layers of cortex, where transient ADC reduction and c-fos expression were observed. The same was true for most rats subjected to 30-min ischemia. However, in a small number of rats of the 30-min group, cox-2 mRNA expression was observed in regions exhibiting transient and persistent ADC reduction with no c-fos expression. The results suggest that cox-2 mRNA expression during acute MCA occlusion is caused by either or both spreading depression and transient ischemic depolarization.     

Bifidobacterium adolescentis Isolated from Different Hosts Modifies the Intestinal Microbiota and Displays Differential Metabolic and Immunomodulatory Properties in Mice Fed a High-Fat Diet

The incidence of obesity, which is closely associated with the gut microbiota and chronic inflammation, has rapidly increased in the past 40 years. Therefore, the probiotic-based modification of the intestinal microbiota composition has been developed as a strategy for the treatment of obesity. In this study, we selected four Bifidobacterium adolescentis strains isolated from the feces of newborn and elderly humans to investigate whether supplementation with B. adolescentis of various origins could alleviate obesity in mice. Male C57BL/6J mice fed a high-fat diet (HFD, 60% energy as fat) received one of the following 14-week interventions: (i) B. adolescentis N4_N3, (ii) B. adolescentis Z25, (iii) B. adolescentis 17_3, (iv) B. adolescentis 2016_7_2, and (v) phosphate-buffered saline. The metabolic parameters, thermogenesis, and immunity of all treated mice were measured. Cecal and colonic microbial profiles were determined by 16S rRNA gene sequencing. Intestinal concentrations of short-chain fatty acids (SCFAs) were measured by gas chromatography-mass spectrometry (GC-MS). The B. adolescentis strains isolated from the feces of elderly humans (B. adolescentis Z25, 17_3, and 2016_7_2) decreased the body weight or weight gain of mice, whilst the strain isolated from the newborn (B. adolescentis N4_N3) increased the body weight of mice. The B. adolescentis strains isolated from the elderly also increased serum leptin concentrations and induced the expression of thermogenesis- and lipid metabolism-related genes in brown adipose tissue. All the B. adolescentis strains alleviated inflammations in the spleen and brain and modified the cecal and colonic microbiota. Particularly, all strains reversed the HFD-induced depletion of Bifidobacterium and reduced the development of beta-lactam resistance. In addition, the B. adolescentis strains isolated from the elderly increased the relative abundances of potentially beneficial genera, such as Bacteroides, Parabacteroides, and Faecalibaculum. We speculate that such increased abundance of commensal bacteria may have mediated the alleviation of obesity, as B. adolescentis supplementation decreased the intestinal production of SCFAs, thereby reducing energy delivery to the host mice. Our results revealed that certain strains of B. adolescentis can alleviate obesity and modify the gut microbiota of mice. The tested strains of B. adolescentis showed different effects on lipid metabolism and immunity regulation, with these effects related to whether they had been isolated from the feces of newborn or elderly humans. This indicates that B. adolescentis from different sources may have disparate effects on host health possibly due to the transmission of origin-specific functions to the host.     

Ethanol sensitivity and tolerance in long-term memory mutants of Drosophila melanogaster

Background:  It has become increasingly clear that molecular and neural mechanisms underlying learning and memory and drug addiction are largely shared. To confirm and extend these findings, we analyzed ethanol-responsive behaviors of a collection of Drosophila long-term memory mutants.
Methods:  For each mutant, sensitivity to the acute uncoordinating effects of ethanol was quantified using the inebriometer. Additionally, 2 distinct forms of ethanol tolerance were measured: rapid tolerance, which develops in response to a single brief exposure to a high concentration of ethanol vapor; and chronic tolerance, which develops following a sustained low-level exposure.
Results:  Several mutants were identified with altered sensitivity, rapid or chronic tolerance, while a number of mutants exhibited multiple defects.
Conclusions:  The corresponding genes in these mutants represent areas of potential overlap between learning and memory and behavioral responses to alcohol. These genes also define components shared between different ethanol behavioral responses.     

Early experience of sentinel lymph node biopsy in breast cancer with blue dye technique

Objective: Sentinel lymph node biopsy (SLNB) is a minimally invasive staging procedure for breast cancer. Results of the first 30 cases of SLNB performed at Kwong Wah Hospital, Hong Kong, were reviewed. Design: This feasibility study applied and assessed a new procedure in Chinese patients. The study was carried out at the Breast Centre, Kwong Wah Hospital, Hong Kong. Sentinel lymph node biopsy was performed with a blue dye technique alone. All patients had full axillary dissection after SLNB. Patients: Female patients with invasive carcinoma of breast and no clinical palpable axillary lymph node were included. Main outcome measures: Pathological results of both the SLN and the remaining axillary content were compared. Results and Conclusion: Sentinel lymph nodes were successfully biopsied in 83% of cases. Sensitivity was 75% and accuracy was 88%. With experience, sentinel lymph node biopsy is feasible in Chinese patients.