Structure-activity relationships of (+)-CC-1065 analogues in the inhibition of helicase-catalyzed unwinding of duplex DNA.

(+)-CC-1065 is a potent antitumor antibiotic produced by Streptomyces zelensis. Previous studies have shown that the potent cytotoxic and antitumor activities of (+)-CC-1065 are due to the ability of this compound to covalently modify DNA. (+)-CC-1065 reacts with duplex DNA to form a (N3-adenine)-DNA adduct which lies in the minor groove of DNA overlapping with a five base-pair region. As a consequence of covalent modification with (+)-CC-1065, the helix bends into the minor groove and also undergoes winding and stiffening. In the studies described here, we have constructed templates for helicase-catalyzed unwinding of DNA that contain site-directed (+)-CC-1065 and analogue DNA adducts. Using these templates we have shown that (+)-CC-1065 and select synthetic analogues, which have different levels of cytotoxicity, all produce a significant inhibition of unwinding of a 3'-tailed oligomer duplex by helicase II when the displaced strand is covalently modified. However, the extent of helicase II inhibition is much more significant for (+)-CC-1065 and an analogue which also produced DNA winding when the winding effects are transmitted in the opposite direction to the helicase unwinding activity. This observed pattern of inhibition of helicase-catalyzed unwinding of drug-modified templates was the same for a 3'-T-tail, for different duplex region sequences, and with the Escherichia coli rep protein. Unexpectedly, the gel mobility of the displaced drug-modified single strand was dependent on the species of drug attached to the DNA. Last, strand displacement by helicase II coupled to primer extension by E. coli DNA polymerase I showed the same pattern of inhibition when the lagging strand was covalently modified. In addition, the presence of helicase II on single-stranded regions of templates caused the premature termination of primer extension by DNA polymerase. These results are discussed from the perspective that (+)-CC-1065 and its analogues have different effects on DNA structure, and these resulting structural changes in DNA molecules are related to the different in vivo biological consequences caused by these drug molecules.     

便携式野战—Ⅰ型多功能骨科手术器械

一种便携式野战多功能骨科手术器械。重量仅１．１ｋｇ，体积为２１５ｍｍ×１０５ｍｍ×１５ｍｍ，如铅笔盒，而功能多达３３种，具有结构紧凑、操作简便、一械多用、轻巧便携。价廉实用、效价比高的特点。是基层巡诊、抢险救灾救治中适用的骨科器械。     

白细胞介素—2新的功能位点及其中枢镇痛作用

白细胞介素－２（ＩＬ－２）不仅是重要的免疫调节因子，而且还具有重要的中枢调节作用。本实验以钾离子透入引起大鼠甩尾反应为指标，发现侧脑室注射ＩＬ—２能显著提高动物痛阈，并能被纳洛酮所阻断，表示ＩＬ－２的中枢镇痛作用可能与阿片受体有关。利用基因定位突变技术获得的无免疫活性ＩＬ－２实查体仍具有中枢镇痛作用，表明ＩＬ—２分子上发挥镇痛和免疫调节作用的功能位点是相互独立的。纳洛酮能够阻断ＩＬ—２的中枢镇痛作用，而不能影响ＩＬ—２增殖ＣＴＬＬ－２细胞的作用，提示ＩＬ－２发挥镇痛和免疫调节作用可能通过不同的受体途径。ＩＬ－２分子中第４５位Ｔｙｒ残基突变为Ｖａｌ后，虽仍保留了免疫活性，但丧失了镇痛功能，表示４５位Ｔｙｒ残基是ＩＬ—２发挥中枢镇痛功能的关键残基之一。我们推测ＩＬ—２的镇痛功能位点可能在ＩＬ—２分子中第４５位Ｔｙｒ残基附近区域。     

A comparative study of pepsinogen (PG) and lactic acid dehydrogenase (LDH) activities and isoenzyme patterns in tissues from human primary gastric cancer, gastric cancer xenografts in nude mice and gastric cancer cell lines]

Tissue and cell homogenates were prepared for PG and LDH study from 20 samples of histologically proven gastric cancer (GC), 6 samples of gastric cancer xenografts (THPGC-1) of different passages (GCXG) and cultured cells of 3 different gastric cancer cell lines (GCCL). Normal gastric mucosa (NGM) was also obtained from the resected stomach far distant from the primary tumor and histologically tumor free. The results indicated that the expression of PG isoenzymes was low or absent and the PG activities were significantly decreased in GC, GCXG and GCCL as compared to NGM. The activity of LDH was also significantly increased in GC, GCXG and GCCL. In addition, there was a change in isoenzyme pattern in GC and GCXG in which isoenzyme type M was observed whereas isoenzyme type H was preponderent in NGM. The results show that the human gastric cancer xenograft, THPGC-1, has biological properties very similar to those of the primary tumor suggesting that THPGC-1 is a reliable model for the study of the molecular biology of human gastric cancer.     

Medullospinal vasomotor neurones mediate hypotension from stimulation of prefrontal cortex.

Electrical stimulation of the prefrontal cortex in anaesthetised, paralysed rats evokes transient hypotension. In this study we have endeavoured to determine whether this evoked response is mediated by the spinal cord-projecting vasomotor neurones of the rostroventrolateral medulla (RVL). The responses of RVL-spinal vasomotor neurones to electrical stimulation of the prefrontal cortex caused a period of inhibition of the neuronal activity in the majority of cases (11 out of 13 neurones tested, 85%) and a short period of excitation in the remaining 2 neurones (15%). The prefrontal cortex-evoked inhibition of RVL-spinal vasomotor neurones was eliminated by iontophoretic application of bicuculline, a GABAa receptor antagonist, to the RVL-spinal vasomotor neurones. Microinjection of 50 nl of bicuculline methiodide into the same area of the RVL where the neurones have been identified converted the prefrontal-evoked hypotension into a vasopressor response. These findings indicate that the hypotension evoked by stimulating the prefrontal cortex is mediated by GABAergic inhibition of the RVL-spinal vasomotor neurones.     

An electrophysiological correlate of protein kinase C isozyme distribution in cultured cerebellar neurons.

Protein kinase C (PKC) is a family of at least seven closely related molecules (isozymes) that vary in terms of their requirements for activation and their distribution among cells of the brain. A striking example of this differential distribution is seen in the cerebellum, where Purkinje cells express PKC-I, an isozyme that is strongly activated by both phorbol ester (PE), and low doses of cis-unsaturated fatty acid (c-UFA), while granule cells predominantly express PKC-II, an isozyme that is strongly activated by PE but not c-UFA. Both Purkinje and granule cells have large, easily recorded voltage-gated K currents. These currents are attenuated by PKC activators in several other varieties of neuron. We hypothesized that the effects of these two PKC activators would be predicted by the distribution of the relevant PKC isozyme, and that the delayed outward rectifier current, IK, would be attenuated by both PE and c-UFA in Purkinje cells, but only by PE in granule cells. This hypothesis was confirmed in perforated-patch recordings. The attenuation produced by both activators could be blocked by application of a specific PKC inhibitor, RO-31-8220, and could not be mimicked by inert forms of PE or c-UFA. To our knowledge, this study represents the first report of an electrophysiological correlate of PKC isozyme distribution.     

移植肾破裂的处理

目的　提高移植肾破裂的防治水平。方法　 6例移植肾破裂 ,手术前 2例 ,手术后 4例。 2例术前供肾破裂 ,采用切开移植肾破裂处包膜 +裂口内明胶海绵填塞 +肠线修补 +肠线编织肾袋收缩保护移植肾。 1例术后移植肾破裂早期 ,出血少 ,针对顽固性高血压采用“硝普钠”降压 ,配合常规抗排斥药物。 3例术后移植肾破裂出血量估计超过 10 0 0ml者 ,采用手术延长移植肾破裂处包膜 +裂口内明胶海绵填塞 +肠线修补 +肠线编织肾袋收缩保护移植肾。结果　 ( 1)手术前 2例手术后 4例 ,采用切开或者延长移植肾破裂处包膜 +裂口内明胶海绵填塞 +肠线修补 +肠线编织肾袋收缩保护移植肾并配合“硝普钠”降压的方法处理 ,均未再破裂出血 ,移植肾功能恢复良好。 ( 2 ) 1例术后移植肾破裂早期的患者 ,针对顽固性高血压采用“硝普钠”降压 ,配合常规抗排斥药物 ,非手术治疗成功。结论　 ( 1)采用手术切开或延长移植肾破裂处包膜 +裂口内明胶海绵填塞 +肠线修补 +肠线编织肾袋收缩保护移植肾可以有效治疗移植肾破裂。 ( 2 )移植肾破裂出血少的情况下 ,可以在密切观察下非手术治疗     

Acquisition of a growth-inhibitory response to phorbol ester involves DNA damage.

TPA (12-O-tetradecanoylphorbol-13-acetate), a potent tumor promoter, has been shown to stimulate or inhibit cell growth depending on the cell type investigated. We recently found that RT101 cells, a transformed mouse JB6 epidermal cell line, acquired a greater growth inhibition response to TPA during conventional subcultivation. The growth of low-passage RT101 cells was slightly inhibited by TPA in monolayer culture but stimulated in soft agar. In contrast, the growth of high-passage cells was greatly inhibited by TPA in both monolayer culture and in soft agar. Inhibition was dose dependent, directly correlated with protein kinase C-activating activities of tumor promoters, and was found to be reversible. TPA-treated high-passage cells were greatly reduced in volume, showed extensive abnormal mitoses, and were more susceptible to detachment. High-passage cells were also found to be less tumorigenic as indicated by in vivo tumorigenicity assay in nude mice. TPA treatment rendered cells still less tumorigenic in the case of both cell lines. The mechanism for acquisition of increased sensitivity to TPA of RT101 cells during subculture was investigated; it involved nonrandom DNA damage and detachment of nonviable cells. The results suggest the possibility that early-passage RT101 cells contained two subpopulations, one TPA-sensitive and one TPA-resistant population. Conventional subcultivation may have selected for the former subpopulation. The sensitive subpopulation may have been irreversibly inhibited as a result of TPA-induced cell killing, possibly apoptosis.     

纤维连接蛋白在膀胱癌丝裂霉素化疗药物耐受中的作用

目的 :探讨纤维连接蛋白 (FN)在膀胱癌化疗药物耐受中的作用。方法 :将T2 4膀胱肿瘤细胞分别接种于包被FN、牛血清蛋白 (BSA)的培养板上孵育 2 4h ,加入不同浓度的丝裂霉素C(MMC)作用 2h ,用MTT比色法检测作用后不同时间肿瘤细胞的存活率 ,用ANNEXINⅤ流式细胞分析仪检测不同时间肿瘤细胞的凋亡率。结果 :FN黏附的膀胱肿瘤细胞在不同浓度MMC作用 2h、12h和 2 4h后的平均存活率为 6 8.3%、4 5 .7%及 5 9.1% ,与BSA黏附的膀胱肿瘤细胞平均存活率 4 5 .0 %、2 1.3%、2 6 .6 %比较 ,差异有统计学意义 (P <0 .0 5 )。FN黏附的膀胱肿瘤细胞在不同浓度MMC作用 2h和 12h后平均凋亡率分别为 1.4 %和 1.0 % ,而BSA组的细胞平均凋亡率为4 .9%和 8.2 % ,两组比较差异有统计学意义 (P <0 .0 1)。结论 :与FN黏附后的膀胱肿瘤细胞对化疗药物MMC的敏感性下降 ,细胞存活率增高 ;FN能抑制MMC引起的膀胱肿瘤细胞凋亡 ,产生药物耐受。     

Innervation of the trapezius muscle: is cervical contribution important to its function?

OBJECTIVE: To study the effect of the cervical plexus and the accessory nerve to the function of the trapezius muscle. STUDY DESIGN AND SETTING: Eighteen adult male Sprague-Dawley rats were randomly divided into three groups. The neurotomies were performed in the left sides and the right sides served as within-subject controls. In group A, the accessory nerve was transected. The C2-5 were transected in group B, and both of the accessory nerve and C2-5 were cut in group C. The electrophysiologic, myophysiologic, and histologic changes of the muscles were measured. RESULTS: There were significant differences (P < 0.05) between the three groups in the recovery rates of the transverse area of the muscles. The CMAP recorded from the experimental sides in group B were similar to the control sides. The values of the maximum tension of the tetanus contraction between the two sides showed no differences either (P > 0.05). CONCLUSION: The accessory nerve supplies the most important motor input to the trapezius. Motor innervations of the cervical plexus are not very significant.