DNA changes involved in the formation of metaphase chromosomes,as observed in mouse duodenal crypt cells stained by osmium-ammine I. New structures arise during the S phase and condense at prophase into “chromomeres,” which fuse at prometaphase into mitotic chromosomes

Background: In the hope of understanding how chromosomes condense at mitosis, we took advantage of a subdivision of the cell cycle into 11 stages to examine the changes in DNA taking place during the stages preceding the emergence of metaphase chromosomes. Methods: To identify DNA changes, pieces of mouse duodenum were fixed in formaldehyde, and sections of the rapidly dividing cells of the crypts were stained by the osmium-ammine method, which is specific for the detection of DNA in the electron microscope. Results: Throughout the cell cycle, DNA is present in nucleofilaments composed of rows of 11-nm-wide nucleosomes. At stage I, during which the DNA-synthesizing or S phase of the cell cycle begins, some of the nucleofilaments are compacted in the heterochromatin accumulations associated with nuclear envelope and nucleoli, while the others are scattered in the nucleoplasm where they appear either “free” or “attached” to the heterochromatin. This DNA distribution is similar to that observed in the noncycling cells examined. After the beginning of the S phase, “free” nucleofilaments are seen to assemble into structures composed of compacted nucleofilaments and referred to as “aggregates”; these make their appearance at stage II and increase in size through stage III up to the end of S during stage IV. Meanwhile, the heterochromatin associated with nuclear envelope and nucleoli expands toward the nucleoplasm in the form of protrusions referred to as “bulges,” which gradually enlarge during stages III and IV, while the heterochromatin shrinks and eventually vanishes. On average, a total of 1,171 aggregates and bulges are formed in the nucleus during the S phase. At the apparition of stage V, which corresponds approximately to prophase, aggregates and bulges are rapidly gathered into an average of 288 spheroidal bodies referred to as “chromomeres.” These are connected to one another by nucleofilamentous bridges in such a way as to be lined up in rows. The formation of rows of chromomeres represents in the electron microscope the prophasic condensation observed in the light microscope. Finally, during stage VIa, which corresponds to prometaphase, the chromomeres approach one another within each row, make contact, and coalesce to become the 40 chromosomes of the mouse, which during stage VIb are organized in the equatorial plate of metaphase. Conclusions: The condensation of metaphase chromosomes occurs in three main steps. The first and longest takes place during the S phase, as nucleofilaments are assembled into aggregates, while the heterochromatin give rise to bulges. The brief second step occurs toward the beginning of prophase, when the numerous aggregates and bulges are congregated into a limited number of chromomeres, which are lined up in rows. The third step takes place during the brief prometaphase, when the chromomeres of a row coalesce into a mitotic chromosome. © 1995 Wiley-Liss, Inc.     

护理干预对糖尿病前期患者的影响

目的探讨护理干预对糖尿病前期患者的影响.方法将200例体检门诊糖尿病前期患者随机分为干预组和对照组.干预组实施综合护理干预,对照组不进行干预,1年后比较两组患者转归情况.结果1年后,干预组血糖、血脂、体重指数均优于对照组(P<0.05),转化为糖尿病发生率亦明显低于对照组(P<0.05).结论对糖尿病前期患者进行综合护理干预,可较好地控制其血糖水平并降低糖尿病发病率.     

彩色多普勒显像对宫旁早期异位妊娠及妊娠黄体鉴别诊断的价值

目的:探讨经阴道彩色多普勒超声显像对宫旁早期异位妊娠及妊娠黄体鉴别诊断的临床价值。方法:经彩色多普勒血流显像对296例宫旁妊娠与234例妊娠黄体进行对比分析,观察附件区异常回声区的血流分布情况,并根据血流速度、充盈度及阻力指数等指标鉴别诊断。结果:宫外孕团块周边及内部血流呈条状、点状的占73.0%,呈无明显血流的占10.1%,PSV:(13.3±9.6)cm/s,RI:(0.43±0.08);妊娠黄体周边血流呈环状或半环状的占96.8%,PSV:(33.2±8.2)cm/s,RI:0.41±0.09。结论:经阴道彩超检查子宫附件区包块的血流分析,能有效鉴别早期异位妊娠及妊娠黄体,具有重要临床价值。     

综合护理干预对糖尿病前期患者的影响

目的:探讨综合护理干预对糖尿病前期患者的影响.方法:将160例门诊糖尿病前期患者随机分为干预组和对照组各80例.两组均未用药治疗,干预组实施综合护理干预,对照组不进行干预,比较两组患者转归情况.结果:干预组糖尿病前期相关知识认知、健康生活方式、体重控制及血糖控制情况均优于对照组(P<0.01).结论:对糖尿病前期患者进行综合护理干预,可较好地控制其血糖水平,降低糖尿病发病危险,值得推广应用.     

早发型重度子痫患者前期发病情况分析及母婴结局临床研究

[目的]探讨早发型重度子痫患者前期发病情况及母婴结局。[方法]将某院收治的早发型重度子痫前期患者97例,依据发病孕周分成A组(28～31周)47例、B组(32～34周)50例,比较两组的母婴结局。[结果]两组病例均无孕产妇死亡和子痫发生;A组的妊娠并发症发生率为38.3%,明显高于B组的18.0%,两组比较差异有统计学意义(P﹤0.05);A组的新生儿窒息发生率为21.3%,明显高于B组的6.0%,且A组的新生儿阿氏评分明显低于B组,两组间差异均有统计学意义(P﹤0.05)。[结论]早发型重度子痫患者前期发病越早,母婴结局越差,临床上应及早发现该类疾病患者,并及时采取正确的保守治疗以改善母婴预后。     

老年前期动脉硬化罹患人群腹主动脉病变的超声检测

目的探讨老年前期(45～59岁)高血压病、高血脂症和糖尿病患者腹主动脉内膜—中层病变情况,研究老年前期动脉硬化罹患人群腹主动脉病变,为临床提供预防和治疗的基础资料。方法应用超声对186例老年前期罹患者与30例对照组进行腹主动脉内膜—中层厚度的检测。所选例数均行超声测量腹主动脉内径、中-内膜厚度及回声变化。结果186例罹患组老年前期患者腹主动脉中层-内膜病变,与正常老年前期对照组进行统计学处理,发现老年前期罹患人群腹主动脉中层—内膜厚度及病变例数均大于对照组。结论本研究表明罹患人群腹主动脉中层—内膜的厚度和斑块,与高血压及高血压合并高脂血症时间的长短呈正相关性。     

老年前期动脉硬化罹患人群腹主动脉病变的超声检测

目的探讨老年前期（45～59岁）高血压病、高血脂症和糖尿病患者腹主动脉内膜-中层病变情况，研究老年前期动脉硬化罹患人群腹主动脉病变，为临床提供预防和治疗的基础资料。方法应用超声对186例老年前期罹患者与30例对照组进行腹主动脉内膜-中层厚度的检测。所选例数均行超声测量腹主动脉内径、中-内膜厚度及回声变化。结果186例罹患组老年前期患者腹主动脉中层-内膜病变，与正常老年前期对照组进行统计学处理，发现老年前期罹患人群腹主动脉中层-内膜厚度及病变例数均大于对照组。结论本研究表明罹患人群腹主动脉中层-内膜的厚度和斑块，与高血压及高血压合并高脂血症时间的长短呈正相关性。     

五年制口腔医学专业牙体牙髓病学前期实习教学改革探讨

牙体牙髓病学前期实习是学生由课堂理论学习通往临床实践操作的桥梁，要提高牙体牙髓病学前期实习的教学效果，教学中需要做到：①了解学生的心理状态，激发学生动手操作的兴趣；②引导学生树立爱伤观念，扎实基本技能；③营造良好教学氛围，进行PBL教学；④以问题为中介促进师生间及学生间的信息交流。     

早期脊髓复苏在急性颈脊髓损伤治疗中的临床意义

目的评价早期脊髓复苏在急性脊髓损伤治疗中的临床意义。方法对86例急性颈脊髓损伤患者,其中脊髓完全性损伤17例,脊髓不完全性损伤69例。早期脊髓复苏方案包括：①保持呼吸道通畅和足够有效的血容量,维持平均动脉血压在100mmHg以上,血氧饱和度在95％以上。②应用大剂量甲基强的松龙或地塞米松等药物治疗。③行颅骨牵引制动或复住颈椎。④早期进行颈椎减压植骨融合内固定术。⑤术后早期应用高压氧治疗。结果死亡6例,失访4例,76例获得12～54个月的随访。随访病例中56例神经功能获得改善,其中完全性损伤组有效率为23．5％,不完全性损伤组有效率为73．9％,总有效率为65．1％。结论颈脊髓损伤后,早期复苏治疗是保留和恢复残存脊髓神经功能较为有效的措施,应在临床积极推广应用。     

五年制口腔医学专业牙体牙髓病学前期实习教学改革探讨

牙体牙髓病学前期实习是学生由课堂理论学习通往临床实践操作的桥梁,要提高牙体牙髓病学前期实习的教学效果,教学中需要做到:①了解学生的心理状态,激发学生动手操作的兴趣;②引导学生树立爱伤观念,扎实基本技能;③营造良好教学氛围,进行PBL教学;④以问题为中介促进师生间及学生间的信息交流。