一例精氨酸加压素受体2基因突变的先天性肾性尿崩症患者的临床及家系研究

报道1例精氨酸加压素受体2( arginine vasopressin receptor2,AVPR2)基因突变导致的先天性肾性尿崩症.提取患者及家属的基因组DNA,PCR扩增AVPR2的全部外显子,扩增产物经纯化后行双向测序,测序结果与基因库中序列进行比对,找出突变位点,利用同源结构模型探讨突变点对AVPR2结构的影响.发现AVPR2基因第6 036位核苷酸碱基T突变为C,导致基因产物的168位氨基酸由亮氨酸突变为精氨酸,该突变点尚未报道.患者母亲和姐姐基因为杂合子,父亲为正常基因型.     

中国致心律失常性右心室心肌病患者常见基因突变检测及临床分析

目的：确定中国致心律失常性右心室心肌病（ARVC）患者相关基因突变的患病率，并探索潜在的基因型-表型关系。方法：根据2010年修订的国际专家组的ARVC诊断标准，对32例有症状且临床诊断为ARVC的汉族患者的基因型和表型进行研究。结果：18例（18/32,56.3%）患者中发现了4个桥粒基因PKP2、desmoplakin(DSP)、desmoglein-2 (DSG2)、desmocollin-2(DSC2)中17个突变，包括6个新突变（6/17,35.3%）；非桥粒基因未发现突变。32例患者检测到的突变中，PKP2突变11例（11/32,34.4%）,DSP突变3例（3/32,9.4%）,DSG2突变3例（3/32,9.4%）,DSC2突变4例（4/32,12.5%）。5例（5/32,15.6%）患者出现多个突变。基因型-表型分析未显示携带突变患者与未携带患者的任何差别。结论：PKP2突变是本组ARVC队列中最常见的突变基因，在本研究中未发现非桥粒基因突变。     

MYH7基因Arg453Cys突变及TNNT2基因Arg102Trp突变所致肥厚型心肌病的临床表型分析

目的分析携带MYH7基因Arg453Cys突变及TNNT2基因Arg102Trp突变的肥厚型心肌病（hypertrophic cardiomyopathy, HCM）患者的临床表型及预后特点。方法 在接受过全外显子组测序的986例HCM患者中,分析携带上述两个突变的HCM患者的临床表型特点,并通过随访分析预后。结果 在986例HCM患者中发现6例（0.6%）患者携带MYH7基因Arg453Cys突变,患者平均诊断年龄为（24.3±7.5）岁,发病年龄较小;随访过程中5例出现病情进展,其中2例出现心血管死亡。986例HCM患者中发现3例（0.3%）患者携带TNNT2基因Arg102Trp突变,均表现为轻度肥厚,平均左心室最大室壁厚度（left ventricular maximum wall thickness, LVMWT）为（17.33±2.05） mm;2例出现病情恶化,1例因心力衰竭死亡。结论 MYH7基因Arg453Cys突变和TNNT2基因Arg102Trp突变在我国HCM患者中相对常见,虽然携带突变的患者临床表型异质性较大,但发生心血管死亡的风险较高。     

凝血酶原基因G20210A变异与妊娠期高血压的相关性研究

目的探讨凝血系统相关基因凝血酶原（FⅡ）基因G20210A突变与妊娠期高血压疾病（HDCP）的关系。方法采用4引物扩增受阻突变体系聚合酶链反应（ARMS-PCR）检测66例HDCP患者胎盘组织（包括妊娠期高血压组12例和子痫前期组54例）与69例正常妊娠胎盘组织FⅡ基因G20210A突变情况。结果与对照组比较HD．cP组和子痫前期组的FⅡ基因型频率和等位基因频率差异均有统计学意义（P均〈0．05）；相对于GG基因型，HDCP组的GA基因型和AA基因人群的比数比（OR）值分别为2．26、3．63，子痫前期组分别为2．41、4．52，子痫前期组A等位基因相对G等位基因的OR值为2．15。结论HDCP患者胎盘组织中凝血系统相关基因FⅡ基因G20210A突变与HDCP可能有关。     

线粒体DNA ND1基因nt3394 T→C突变与老年人2型糖尿病

目的：了解线粒体烟酰胺腺嘌呤脱氧核苷酸（NADH）脱氢酶第一亚单位（ND1）基因中339位点T→C突变与我国老年人2型糖尿病的关系。方法：收集无血缘关系的208例老年2型糖尿病患者，同时以180例无糖尿病家族史的老年糖耐量正常者作为对照，用聚合酶链反应扩增。限糖尿病患者，同时以180例无糖尿病家族史的老年糖耐量正常者作为对照，用聚合酶链反应扩增、限制性内切酶HaeⅢ消化进行点突变筛选。结果：发现9例患者存在线粒体DNA ND1基因3394位点T→C突变（4．3％），非糖尿病者中仅有1例突变（0．6％），两组比较差异有显著性（P＜0．05）。结论：线粒体DNA ND1基因中3394位点T→C突变可能与我国老年人2型糖尿病的发病有关。     

心脏型肌球蛋白结合蛋白C基因13261 G＞A突变导致肥厚型心肌病的临床表型分析

目的研究中国人肥厚型心肌病致病基因,分析基因型与临床表型的关系。方法在一肥厚型心肌病家系中进行心脏型肌球蛋白结合蛋白C基因（MYBPC3）和β-肌球蛋白重链基因（MYH7）突变筛查,利用聚合酶链反应（PCR）扩增其功能区的外显子片段,双脱氧末段终止法测序。家系调查资料包括临床表现、体格检查、心脏超声和心电图。结果在该家系27例有血缘关系的研究对象中9例携带MYBPC3 13261 G〉A（G758D）突变,正常对照组同一位置未见异常。该突变位点是MYBPC3基因第23号外显子的甘氨酸突变为天冬氨酸,其中2例携带者发病,一例表现为心室扩大,左室射血分数减低等扩张型心肌病样表现,伴室间隔不对称肥厚,厚度为14mm,另外一例患者为典型的肥厚型心肌病表现。MYH7基因未发现突变。结论MYBPC3基因13261 G〉A突变是该肥厚型心肌病家系的致病突变,其外显率为22％,其中一例患者表现为肥厚型心肌病的扩张相,MYBPC3基因G758D突变可能是肥厚型心肌病进展为扩张型心肌病样改变的原因之一。对临床表现为扩张型心肌病的患者进行家族史调查及基因检查十分必要。     

湖南地区肝豆状核变性基因突变热区的序列检测与分析

目的检测湖南地区汉族人群肝豆状核变性患者（WD）ATP7B基因常见突变种类和形式。方法提取22例WD患者外周血基因组DNA，聚合酶链反应（PCR）扩增ATP7B基因第5、8、12及13号外显子并进行DNA直接测序检测，应用在线BLAST软件分析。结果22例患者中共发现15例患者存在基因突变。其中10例患者存在8号外显子2273G→T杂合突变（即Arg778Leu），且均伴有2250C→G多态（即Leu770Leu，均为杂合子），未发现纯合突变。12号外显子中共发现2855G→A多态（即Arg952Lys）7例（杂合突变4例，纯合突变3例），其中1例合并12号外显子2828G→A杂合突变（即Gly943Asp），另3例合并Arg778Leu杂合突变。13号外显子2975C→T杂合突变（即Pro992Leu）1例。5号外显子未发现突变。结论Arg778Leu是湖南地区汉族WD患者的突变热点，5号外显子为非突变热点。     

正常核型急性髓系白血病NPM1基因突变的临床研究

目的探讨正常核型急性髓系白血病（AML）患者核仁磷酸蛋白1（NPM1）基因突变发生情况,并了解其临床特征及预后。方法采用基因组DNA-PCR方法检测123例初发AML患者NPM1基因及正常核型AML患者FMS样酪氨酸激酶3（FLT3）基因,直接测序法检测AML患者NPM1基因第12外显子的突变情况,琼脂糖电泳分析正常核型AML患者FLT3基因内部串联重复（ITD）突变。结果 123例AML患者中检出NPM1突变24例（19.5%）,其中A型突变22例、B型突变1例、D型突变1例。57例正常核型中FLT3-ITD阳性10例,其中5例同时发生NPM1和FLT3-ITD两种突变。NPM1突变在正常核型中的发生率为40.3%（23/57）,显著高于异常核型的2.1%（1/47）（P〈0.01）。正常核型中NPM1基因突变者发病年龄高、缓解率高,但合并FLT3-ITD突变者缓解率低。结论 NPM1基因突变是AML尤其是正常核型AML患者常见的分子学异常,NPM1基因突变检测对指导AML患者治疗及评估预后有重要意义。     

乙型肝炎病毒基本核心启动子突变与基因型的关系

目的研究乙型肝炎病毒（HBV）基本核心启动子（BCP）突变与HBV基因型的关系。方法随机选取我院68例慢性乙型肝炎患者外周血，采用荧光定量PCR结合TaqmanMGB探针技术检测HBV基因型，并用基因扩增和DNA测序方法检测BCPT1762／A1764双突变。结果68例患者HBV分型中，B基因型20例，C基因型46例，B、C混合型1例，未分型（非B非C型）1例。66例B、C两基因型中，B基因型组T1762／A1764双突变5例，突变率25．0％（5／20），C基因型组T1762／A1764双突变24例，突变率52．2％（24／46），C基因型T1762／A1764双突变率明显高于B基因型（P〈0．05）。结论苏州地区慢性乙型肝炎患者基因型以C型和B型为主，C基因型比B基因型更易发生T1762／A1764双突变。     

中国大陆人散发性先天性巨结肠症患者内皮素受体B基因的研究

目的 探讨中国大陆人散发性先天性巨结肠症（sHD）易患基因内皮素受体B（EDNRB）的突变与多态性特征。方法 以92例sHD及其中32例患儿双亲为研究对象，并以60例正常儿为对照。提取受检者外周静脉血DNA，采用聚合酶链反应-单链构象多态性技术（PCR-SSCP）对EDNRB基因外显子-2（exon-2）进行分析，并通过DNA测序检测阳性标本的核苷酸改变方式，与文献报道的其他种族sHD同一基因特征做比较。结果 全部标本EDNRB基因exon-2均未发现突变与多态性位点的存在。结论 中国大陆人sHD患者EDNRB基因的exon-2不存在突变与多态性位点。     

Clostridial toxins: sensing a target in a hostile gut environment

The current global outbreak of Clostridium difficile infection exemplifies the major public health threat posed by clostridial glucosylating toxins. In the western world, C. difficile infection is one of the most prolific causes of bacterial-induced diarrhea and potentially fatal colitis. Two pathogenic enterotoxins, TcdA and TcdB, cause the disease. Vancomycin and metronidazole remain readily available treatment options for C. difficile infection, but neither is fully effective as is evident by high clinical relapse and fatality rates. Thus, there is an urgent need to find an alternative therapy that preferentially targets the toxins and not the drug-resistant pathogen. Recently, we addressed these critical issues in a Nature Medicine letter, describing a novel host defense mechanism for subverting toxin virulence that we translated into prototypic allosteric therapy for C. difficile infection. In this addendum article, we provide a continued perspective of this antitoxin mechanism and consider the broader implications of therapeutic allostery in combating gut microbial pathogenesis.     

Jejuno-jejunal intussusception in a hemophiliac: a case report

Reported is a case of jejuno-jejunal intussusception with an intramural hematoma as a lead point, occurring in a hemophiliac after blunt trauma to the abdomen. Exploratory laparotomy was performed, the jejunal hematoma was evacuated, and the intussusception was reduced. No similar case was found in the literature.     

Forensic echocardiography: a case in point

Transthoracic echocardiography (TTE) has an important role in the assessment of patients with acute penetrating chest trauma. We report the case of a 36-year-old man who sustained a stab wound to the chest. After admission, he required emergency pericardiocentesis. TTE revealed a traumatic ventricular septal defect and a defect in the anterior mitral valve leaflet. To assess whether these lesions were related to the initial stab wound or the pericardiocentesis, the transducer was positioned over the stab wound, and the lesions were shown to be in the same plane as the entry site, thus ruling out iatrogenic trauma.     

Glucagon,a useful adjunct in anastomosis with a stapling device

Spasm of the proximal sigmoid colon has been a major hindrance in the use of the EEA stapler in low anterior resections. Intravenous glucagon, by causing rapid relaxation and hypotonicity of the sigmoid colon, appears to help correct this problem and allows for a safer and more atraumatic anastomosis. Read at Residents' Participation Night, New York Society of Colon and Rectal Surgeons. New York, New York, March 8, 1979.     

Rapid protection in a monkeypox model by a single injection of a replication-deficient vaccinia virus

The success of the World Health Organization smallpox eradication program three decades ago resulted in termination of routine vaccination and consequent decline in population immunity. Despite concerns regarding the reintroduction of smallpox, there is little enthusiasm for large-scale redeployment of licensed live vaccinia virus vaccines because of medical contraindications and anticipated serious side effects. Therefore, highly attenuated strains such as modified vaccinia virus Ankara (MVA) are under evaluation in humans and animal models. Previous studies showed that priming and boosting with MVA provided protection for >2 years in a monkeypox virus challenge model. If variola virus were used as a biological weapon, however, the ability of a vaccine to quickly induce immunity would be essential. Here, we demonstrate more rapid immune responses after a single vaccination with MVA compared to the licensed Dryvax vaccine. To determine the kinetics of protection of the two vaccines, macaques were challenged intravenously with monkeypox virus at 4, 6, 10, and 30 days after immunization. At 6 or more days after vaccination with MVA or Dryvax, the monkeys were clinically protected (except for 1 of 16 animals vaccinated with MVA), although viral loads and number of skin lesions were generally higher in the MVA vaccinated group. With only 4 days between immunization and intravenous challenge, however, MVA still protected whereas Dryvax failed. Protection correlated with the more rapid immune response to MVA compared to Dryvax, which may be related to the higher dose of MVA that can be tolerated safely.     

Extreme polyploidy in a large bacterium

Cells rely on diffusion to move metabolites and biomolecules. Diffusion is highly efficient but only over short distances. Although eukaryotic cells have broken free of diffusion-dictated constraints on cell size, most bacteria and archaea are forced to remain small. Exceptions to this rule are found among the bacterial symbionts of surgeonfish; Epulopiscium spp. are cigar-shaped cells that reach lengths in excess of 600 mum. A large Epulopiscium contains thousands of times more DNA than a bacterium such as Escherichia coli, but the composition of this DNA is not well understood. Here, we present evidence that Epulopiscium contains tens of thousands of copies of its genome. Using quantitative, single-cell PCR assays targeting single-copy genes, we have determined that copy number is positively correlated with Epulopiscium cell size. Although other bacteria are known to possess multiple genomes, polyploidy of the magnitude observed in Epulopiscium is unprecedented. The arrangement of genomes around the cell periphery may permit regional responses to local stimuli, thus allowing Epulopiscium to maintain its unusually large size. Surveys of the sequences of single-copy genes (dnaA, recA, and ftsZ) revealed genetic homogeneity within a cell consistent with only a small amount ( approximately 1%) of the parental DNA being transferred to the next generation. The results also suggest that the abundance of genome copies in Epulopiscium may allow for an unstable genetic feature, a long mononucleotide tract, in an essential gene. With the evolution of extreme polyploidy and large cell size, Epulopiscium has acquired some of the advantages of eukaryotic cells.     

Long-term effects of a trophic cascade in a large lake ecosystem

Introductions or invasions of nonnative organisms can mediate major changes in the trophic structure of aquatic ecosystems. Here we document multitrophic level impacts in a spatially extensive system that played out over more than a century. Positive interactions among exotic vertebrate and invertebrate predators caused a substantial and abrupt shift in community composition resulting in a trophic cascade that extended to primary producers and to a nonaquatic species, the bald eagle. The opossum shrimp, Mysis diluviana, invaded Flathead Lake, Montana, the largest freshwater lake in the western United States. Lake trout had been introduced 80 y prior but remained at low densities until nonnative Mysis became established. The bottom-dwelling mysids eliminated a recruitment bottleneck for lake trout by providing a deep water source of food where little was available previously. Lake trout subsequently flourished on mysids and this voracious piscivore now dominates the lake fishery; formerly abundant kokanee were extirpated, and native bull and westslope cutthroat trout are imperiled. Predation by Mysis shifted zooplankton and phytoplankton community size structure. Bayesian change point analysis of primary productivity (27-y time series) showed a significant step increase of 55 mg C m(-2) d(-1) (i.e., 21% rise) concurrent with the mysid invasion, but little trend before or after despite increasing nutrient loading. Mysis facilitated predation by lake trout and indirectly caused the collapse of kokanee, redirecting energy flow through the ecosystem that would otherwise have been available to other top predators (bald eagles).