Mechanics and Ca2+-sensitivity of human detrusor muscle bundles studied in vitro

Mechanical properties of isolated smooth muscle strips from human urinary bladder were investigated in vitro. Bladder tissue was obtained from tumour-free wall regions of bladders from male patients undergoing cystectomy for bladder carcinoma. In intact muscle strips, activated with high-K⁺ solution, half-maximal force occurred at about 0.9 mm extracellular [Ca²⁺]. The length-active force relation was determined and the muscle strips were fixed for light and electron microscopy at optimal length for active force (I_o). The maximal active force per unit smooth muscle cross-sectional area was 208±49 mN/mm², n= 6. Chemically skinned preparations were obtained by treatment with triton X-100. These preparations had a steep [Ca²⁺]-force relation in the micromolar range which was influenced by calmodulin. The skinned preparations could be maximally activated by irreversible thiophosphorylation of the regulatory light chains. The force-velocity relation was determined in the maximally activated skinned muscle at 22 °C at 0.5 1_o. When the muscle was shortened by 10%, force was reduced by 35% whereas the maximal shortening velocity was little affected.     

Telomere structure, function and maintenance in Arabidopsis

The stability of eukaryotic genomes is provided in part by the integrity of telomeres, the nucleoprotein caps on the ends of chromosome. Recent studies reveal that proper telomere architecture is required for long-term proliferation capacity. Here we describe molecular mechanisms that protect and maintain chromosome ends and discuss why Arabidopsis is emerging as a powerful new model for elucidating fundamental aspects of telomere biology.     

Lactate dehydrogenase activity and isoform distribution in normal and hypertrophic smooth muscle tissue from the rat

The lactate dehydrogenase (LDH) activity and isoform distribution of LDH were investigated in tissue samples from the rat portal vein, aorta and urinary bladder. In addition, samples were obtained from hypertrophic urinary bladder. The total LDH activity per unit smooth muscle volume was higher in the urinary bladder compared to that in portal vein and aorta. Five LDH isoforms, reflecting different combinations of the two polypeptide chains denoted H and M, could be separated by agarose gel electrophoresis. The aorta contained more of the H form compared to the portal vein and urinary bladder. This difference suggests that the aorta, which is a slow smooth muscle, is more adapted for aerobic metabolism than the faster muscles of portal vein and urinary bladder. In the hypertrophic urinary bladder a shift in LDH isoform pattern towards less of the H form was found, which correlates with a better maintenance of contraction in anoxia in this type of hypertrophic smooth muscle.     

肺炎克雷伯杆菌在T24细胞内存活的动态观察

目的：了解肺炎克雷伯杆菌与膀胱上皮细胞的相互关系，观察肺炎克雷伯杆菌在人膀胱上皮细胞抹T24中生存的动态变化。方法：采用肺炎克雷伯杆菌临床分离抹03138侵袭T24细胞，并用庆大霉素杀死细胞外的细菌，分别于细菌进入细胞后的4、24、48及72h裂解细胞，释放出细胞内的活细菌，用平板菌落计数法计数胞内活菌数。结果：T24细胞内的肺炎克雷伯杆菌03138抹在实验48h内有一定生长，试验72h细胞内活菌数量明显减少。加入细胞因子（TNF-αd和INF-γ）可以促进上皮细胞清除胞内细菌。结论：膀胱上皮细胞清除进入细胞内的肺炎克雷伯杆菌，可能是泌尿道天然免疫的一种防御机制，而细胞因子可以调控上皮细胞的抗菌作用。     

家兔躯体(坐骨神经)和内脏(膀胱)初级传入神经元向骶髓后连合核区的投射—HRP跨越神经节追踪观察

本文作者研究了膀胱(内脏)及坐骨神经(躯体)初级传入纤维向脊髓的投射。发现内脏传入纤维和躯体本体觉粗纤维都向S_2—S_4节段后连合核区投射,两者的投射区有重叠。推测内脏传入和躯体本体觉传入的纤维在后连合核可能有汇聚。另外,根据躯体本体党纤维在髓内跨节段分布的范围和位置以及盆腔脏器初级传入的投射位置,结合文献分析和讨论了脊髓后连合核的位置和形态。提出在脊髓内存在着一个和脑部的孤束核在形态及功能上酷似的脊髓后连合核的见解。它在吻侧以对称的狭细细胞带起于胸髓下段,向尾侧逐渐扩大位于Ⅵ层内侧部,到骶髓成为位于中央管背外方的核团,S_3以下两侧者合并形成位于中央管背侧后连合区的较大核团,一直可追踪到尾髓。     

EB病毒转化B淋巴细胞建立的永生细胞株长期传代遗传稳定性的研究

目的 研究EB病毒转化外周血B淋巴细胞建成的永生细胞株在传代过程中遗传特性是否发生改变.方法 对10株永生细胞株进行30代的长期传代培养,采用染色体显带、微卫星DNA及端粒酶活性检测技术,观察不同传代次数的永生细胞株二倍性、染色体核型、微卫星DNA及端粒酶活性的改变.结果 永生细胞株在30代以内,在染色体二倍性、核型、微卫星DNA方面保持稳定,未检测出端粒酶活性.结论 经EB病毒转化的永生细胞株在有限代次内遗传特征是稳定的.     

基质金属蛋白酶3和尿激酶型纤溶酶原激活物受体在2型糖尿病大血管病变中的变化

目的： 探讨基质金属蛋白酶3（MMP-3）和尿激酶型纤溶酶原激活物受体（uPAR）在2型糖尿病大血管病变中的变化。方法: 用ELISA双抗体夹心法测定26例正常对照和39例2型糖尿病患者（其中单纯2型糖尿病15例、合并大血管病变24例）的血浆MMP-3和uPAR水平。结果: 单纯糖尿病组uPAR高于正常对照（P<0.05）而MMP-3无显著差异；合并大血管病变组MMP-3显著高于正常对照和单纯糖尿病组（P<0.01，P<0.01），而uPAR亦高于正常对照及单纯病变组（P<0.01，P<0.05）。2型糖尿病血浆MMP-3水平和uPAR水平呈正相关， LDL-C与uPAR呈正相关且是uPAR主要影响因素。 结论: MMP-3和uPAR与2型糖尿病大血管病变发生密切相关，MMP-3可作为2型糖尿病血管病变的循环标志物。     

Energy turnover and lactate dehydrogenase activity in detrusor smooth muscle from rats with streptozotocin-induced diabetes

Force generation and tissue glucose metabolism were measured in the urinary bladder smooth muscle from rats with streptozotocin-induced diabetes (7–8 wk duration). Bladder wet wt was almost 4–fold higher in the diabetic animals compared with the untreated controls. Morphological analysis showed that the growth was associated with hypertrophy of the smooth muscle component in the bladder wall. Force generation of isolated bladder strip preparations was measured in vitro at different ambient oxygen tensions. Activation of intramural nerves, with electrical field stimulation, induced contractions that were unaffected by reduction of oxygen tension down to Po₂ 100 mmHg for both control and diabetic muscle strips. At zero Po₂ force was reduced by approximately 10–20% in both groups. High-K⁺ solution induced ‘tonic’ contractions that were slightly more inhibited by lowering Po₂. At intermediate Po₂ (between 100 and 20 mmHg) the diabetic muscle gave slightly higher force. At zero Po₂ no significant difference could be detected between strips from control and diabetic animals. Oxygen consumption and lactate production in the preparations were determined at a Po₂ of 290 mmHg and related to the volume of smooth muscle. At zero Po₂ lactate formation increased 3- to 4-fold. The metabolic tension cost was lower at zero Po₂ No differences in basal and contraction related metabolic rates could be detected between the two groups under normoxic and anoxic conditions. The maximal activity of lactate dehydrogenase (LDH) determined in tissue sampIes was about 2-fold higher in the diabetic bladder muscle. This increased enzymatic activity could thus not be correlated with any altered metabolic properties of the smooth muscle in the urinary bladder from diabetic rats.     

Immunohistochemically demonstrated variation in expression of cathepsin E between uracil-induced papillomatosis and N-butyl-N-(4-hydroxybutyl)nitrosamine-induced preneoplastic and neoplastic changes in rat urinary bladder

Expression of rat urinary bladder cathepsin E in benign papillomatosis induced by uracil and various stages of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced carcinogenesis was investigated immunohistochemically. Seven-week-old, male F344/DuCrj rats were used. In the normal urothelium of control rats, cathepsin E stained in all layers of cells, although in umbrella cells and some basal cells the reaction was relatively weak. In rats given a diet containing 3% uracil for 5 weeks immunoreactivity of cathepsin E in uracil-induced papillomatosis was consistently homogeneous in all layers, but weaker than in normal urothelium. In rats given 0.05% BBN in drinking water for 12 weeks and subsequently maintained without treatment for 48 weeks cells with little cathepsin E, never observed in normal urothelium, appeared at 5 weeks above the basement membrane in the earliest stage of BBN-induced urinary bladder cancer (simple hyperplasia). Throughout the neoplastic process, groups of cells with a little cathepsin E were randomly distributed, with expression in the urothelium being markedly unstable. Almost all areas of squamous cell proliferation in TCC were negative for cathepsin E. Instability of cathepsin E expression in rat urothelium therefore appears characteristic for carcinogenesis and offers the possibility of using this feature as an early biomarker for urinary bladder carcinogenesis.