儿童幽门螺杆菌感染

幽门螺杆菌感染不仅能引起胃炎、消化性溃疡,诱发胃癌等胃肠道的病变,还与许多胃肠外疾病密切相关,如果不经过特殊治疗将终生带菌,严重的影响小儿的生长发育和身心健康。这些问题引起了儿科医生和儿童保健医生的共同关注。儿童期既是幽门螺杆菌感染的特殊时期,也是控制感染的关键时期。本文将从小儿幽门螺杆菌国内外的感染状况、相关疾病、诊断方法、治疗及预防等几个方面综述如下。     

端粒酶活性与幽门螺杆菌相关性胃疾病

端粒酶在胃肿瘤的发生发展中可能具有重要作用,幽门螺杆菌感染与胃肠道疾病的关系密切,且幽门螺杆菌已被列为第一类致癌因子,近年来,一些研究显示了幽门螺杆菌感染与端粒酶活性之间存在一定关系,本文就端粒酶与幽门螺杆菌相关性胃疾病予以综述。     

幽门螺杆菌与胃癌

幽门螺杆菌(Helicobacter pylori,Hp)是一种革兰阴性微需氧菌,世界上约50%的人群有Hp感染.感染通常发生在儿童时期,如不进行治疗,可终身定植于人的胃黏膜上皮,引起多种胃肠道疾病.     

幽门螺杆菌

幽门螺杆菌是一种呈螺旋状或S形、微需氧的革兰阴性杆菌,专一性定居于人胃,是人类慢性胃炎、消化性溃疡、胃癌和胃MALT淋巴瘤的主要病因。幽门螺杆菌在人群中的感染率非常高,达40%~90%,通常在儿童期感染,而且一经感染,若不根除治疗,将终生携带,携带者是幽门螺杆菌的传染源。幽门螺杆菌感染的诊断有侵入性方法如细菌培养、快速脲酶试验等,亦有非侵入性方法如脲呼吸试验、抗体检测等。幽门螺杆菌感染引起胃-十二指肠疾病的机制涉及细菌本身毒力因子、细菌黏附与定植、宿主炎症/免疫反应、氧化应激、细胞的增殖与凋亡等,情况复杂。迄今,幽门螺杆菌的确切致病机制未有定论。幽门螺杆菌相关疾病的治疗普遍采用根除细菌的抗菌疗法。预防幽门螺杆菌感染以及治疗幽门螺杆菌相关疾病的疫苗正在研究中。     

幽门螺杆菌球状体的研究进展

幽门螺杆菌在体内外各种不利因素的作用下可转变为球状体。该菌球状体是一种有活力但不能培养成活的幽门螺杆菌形态变异体,可能在幽门螺杆菌感染的传播途径及其相关性消化系统疾病的复发中发挥重要作用。本文拟对幽门螺杆菌球状体的诱变因素、超微结合、分子生物学特征、毒力以及与疾病的关系、与原生质球的区别等方面作一综述。     

儿童幽门螺杆菌感染与胃肠外疾病相关性的研究进展

幽门螺杆菌（Hp）感染是儿童慢性活动性胃炎和消化性溃疡的主要原因。有证据显示Hp感染在一些胃肠外疾病中也起一定作用,特别是Hp感染与儿童缺铁性贫血、特发性血小板减少性紫癜、生长发育障碍等有较为密切的关系。本文就近期Hp感染与胃肠外疾病的研究进展作一综述。     

益生菌对腹痛儿童幽门螺杆菌根除的影响

目的观察微生态制剂金双歧(双歧杆菌、乳杆菌和嗜热链球菌三联活茵片)对腹痛儿童幽门螺杆菌根除治疗的影响。方法将54例幽门螺杆菌(H.pylori)阳性的腹痛儿童随机分成A组(奥美拉唑、克拉霉素、阿莫西林三联疗法)和B组(金双歧联用三联疗法),疗程均为2周,治疗结束4周后复查13C-尿素呼气试验,统计患儿治疗期间的不良反应。结果 A、B两组根除根除率分别为74.3%和88.8%,差异无统计学意义(P>0.05);B组胃肠道不良反应明显少于A组(P<0.01)。结论微生态制剂不能显著增加腹痛儿童幽门螺杆菌根除率,但降低三联根除疗法的胃肠道不良反应。     

幽门螺杆菌感染动物模型与疫苗发展

目前认为人是幽门螺杆菌的唯一自然感染宿主,常见其他动物中虽然螺杆菌属细菌感染相当普遍,但并未发现有幽门螺杆菌的自然感染存在;用临床分离的普通幽门螺杆菌菌株感染动物发现,仅有雪貂等少数动物可感染;从大量菌株中筛选出的能够成功定植大、小鼠的幽门螺杆菌菌(如SS1菌株等),虽在致病机制研究及临床药物筛选中发挥了重要作用,但由于其具有与在人类不同的黏附定居机制,无法成功地作为疫苗效果评价中的动物模型使用,国内外使用者均遇到了疫苗动物保护率与在人群中保护率的明显反差问题,成为幽门螺杆菌疫苗发展中的主要瓶颈之一。当前幽门…     

聚合酶链反应检测人动脉粥样硬化斑中肺炎衣原体和幽门螺杆菌的DNA

肺炎衣原体和幽门螺杆菌能分别引起呼吸系统和胃肠道的持续感染,研究显示这些菌持续感染动脉可能引起动脉粥样硬化的发生.本文通过聚合酶链反应(PCR)检测动脉粥样硬化斑中肺炎衣原体和幽门螺杆菌(Hp)DNA,研究动脉粥样硬化与肺炎衣原体和Hp感染之间的关系.     

幽门螺杆菌感染对胃肠道菌群影响及其与胃部疾病相关性的研究进展

幽门螺杆菌(H.pylori)是一种定植在胃黏膜上皮的革兰阴性螺旋杆菌,可以诱发多种消化系统疾病,全球有一半以上的人感染H.pylori。在人体复杂而庞大的胃肠道微生态系统中,H.pylori可通过影响胃内环境来降低胃肠道菌群丰富度及多样性。胃肠道菌群与H.pylori共同作用,影响消化性溃疡、胃癌及缺铁性贫血等一系列消化系统疾病的发生发展,但其具体致病机制尚不明确。根除H.pylori可以提高胃肠道菌群的多样性,有助于预防H.pylori相关疾病的代际传播和进一步发展。H.pylori治疗期间补充益生菌可提高根除率,减少抗生素相关不良反应的发生。本文就H.pylori与胃肠道菌群关系的研究进展作一综述,以期探讨H.pylori的致病机制。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.