Ovalbumin gene: evidence for a leader sequence in mRNA and DNA sequences at the exon-intron boundaries.

Selected regions of cloned EcoRI fragments of the chicken ovalbumin gene have been sequenced. The positions where the sequences coding for ovalbumin mRNA (ov-mRNA) are interrupted in the genome have been determined, and a previously unreported interruption in the DNA sequences coding for the 5' nontranslated region of the messenger has been discovered. Because directly repeated sequences are found at exon-intron boundaries, the nucleotide sequence alone cannot define unique excision-ligation points for the processing of a possible ov-mRNA precursor. However, the sequences in these boundary regions share common features; this leads to the proposal that there are, in fact, unique excision-ligation points common to all boundaries.     

6-氟喹诺酮类衍生物的合成及抗菌活性

报道一系列7,8-双取代的1-环丙基和1-乙基-6-氟-1,4-二氢-4-氧-3-喹啉羧酸衍生物的合成和体外抗菌活性。其中,1-环丙基-6-氟-7-(4-乙酰氧基哌啶)-8-氯-1,4-氢-4-氧-3-喹啉羧酸(11c)和1-环丙基-6-氟-7-(4-羟基哌啶)-8-氯-1,4-二氢-4-氧-3-喹啉羧酸(11b)同环丙沙星相比有更强的体外活性,尤其对金黄色葡萄球菌、耐甲氧青霉素金葡菌(MRSA)和绿脓杆菌。     

Frequency of Asymptomatic Hepatitis Types B and C in an Inner City Community and Relation to Possible Risk Factors

The frequency of asymptomatic carriage of the hepatitis virustypes B and C in an inner city area (South London) was assessedin a survey of 1002 subjects attending their General Practitionerfor minor, non-hepatic complaints. Ten subjects were seropositivefor hepatitis B surface antigen (HBsAg) (1 per cent), but onlyone, who declined liver biopsy, had any clinical laboratoryevidence of hepatitis B virus-related chronic liver disease.Carriage of, and exposure to, hepatitis B virus was significantlymore frequent among people born outside the UK/Eire and thosewith a history of jaundice. Among people of Caribbean originthe frequency of hepatitis B virus markers fell from 31 percent among those born in the Caribbean to 11 per cent amongstsecond generation subjects born in this country. Despite carefulcounselling, offers of further investigation and treatment ofthose affected, and vaccination of vulnerable children or partners,were often declined. Four percent of the same population hadantibodies to the hepatitis C virus using the Ortho anti-hepatitisC virus enzyme-linked immunosorbent assay but this figure fellto 0.9 per cent when a second test, based on synthetic peptidesrather than a recombinant antigen, was used. None had any abnormalityof standard liver function tests. Chronic asymptomatic carriage of hepatitis, particularly ininner city areas, may be more common than previously recognized.Effective use of antiviral agents and vaccination will be limiteduntil appropriate health education dispels the widespread misconceptionsand fears associated with a diagnosis of chronic viral hepatitis.     

Spinobulbar muscular atrophy: polyglutamine-expanded androgen receptor is proteolytically resistant in vitro and processed abnormally in transfected cells

The neuronotoxicity of genes with expanded CAG repeats is most likely mediated by their respective polyglutamine (Gln)-expanded gene products. Gln- expanded portions of these products may be sufficient, or necessary, for pathogenesis. We tested whether a Gln-expanded human androgen receptor (AR) is structurally altered, so that it allows for the proteolytic generation of a potentially pathogenic portion that may be resistant to further degradation. We found, in vitro , that a Gln- expanded AR is more proteolytically resistant than normal, and that it yields a distinct set of Gln-expanded fragments even after extended proteolysis in the presence of 2 M urea. Furthermore, COS cells transfected with CAG-expanded AR cDNA generate an aberrant, nuclear- associated 75 kDa derivative containing the Gln-expanded tract. They are also twice as likely to die by 24 h apoptotically than those transfected with normal AR cDNA. Our data support the notion that an unconventional derivative of the Gln- expanded AR is a component of the proximate motor neuronopathic agent in spinobulbar muscular atrophy. They also focus attention on two ways in which neuronotoxic derivatives may originate from various Gln-expanded proteins: (i) generation of an unusual derivative that is pathogenic de novo ; and (ii) the toxic accumulation of a normal derivative because of an inability to dispose of it.      

银川地区Hp阳性患者慢性胃病患者血清Hp-CagA IgG测定

0　引言　我们于 1999- 0 2 /1999- 0 6采用斑点金免疫渗滤试验(dot immunogold fitrationassay,DIGFA)对银川地区慢性胃病 Hp阳性患者行血清 Hp- Cag A Ig G测定 ,现报道如下 .1　材料和方法1.1　材料　本院胃镜室 1999- 0 2 /1999- 0 6经纤维胃镜及病理诊断确诊 ,慢性胃病 Hp阳性患者 2 6 0 (男 143,女 117)例 .年龄 15～ 85 (中位 43)岁 .慢性浅表性胃炎 45例 ,慢性萎缩性胃炎 144例 ,消化性溃疡 48例 ,胃癌 2 3例 .1.2　方法　空腹行纤维胃镜检查 ,用消毒过的活检钳在胃窦部取胃黏膜 1块 ,取 1min快速型 Hp诊断试纸 (珠海珠信生物…     

肾组织环磷酸鸟苷通过直接的肾小管作用引起泌钠作用

目的　检测NO(一氧化氮)和cGMP(环磷酸鸟苷)可引起肾脏泌钠作用的假设。方法　cGMP及其类似物,NO合成酶底物通过微透析泵输入肾组织间隙以及肾动脉。通过慢性及急性动物实验,观察肾脏泌钠作用及血流动力学变化。结果　肾组织间隙给予cGMP及其8-Br-cGMP1μg/h,使24h尿钠排出从对照组(0.6±0.1)mmol/24h增加到(1.2±0.10)mmol/24h及(2.15±0.42)mmol/24h(P＜0.001)。蛋白激酶G抑制剂Rp-8-pCPT-cGMP能够拮抗二者的利钠作用,L-精氨酸(L-Arg)(NO合成酶底物)40mg*kg-1*min-1可引起尿钠排出增加(急性动物实验),从对照组(1.6±0.1)μmol/30min到(4.1±0.1)μmol/30min(P<0.001),这一效应能被可溶性鸟苷酸环化酶的抑制剂ODQ阻断。NO供体SNAP可增加肾脏利钠作用从(1.65±0.11)μmol到(2.93±0.08)μmol/30min(P＜0.001),这一效应同样被ODQ阻断。肾动脉输入cGMP(3μg/min),可引起尿钠排出增加,肾血流量及肾小球滤过率增加。肾组织cGMP增加肾脏泌钠作用,但不影响肾血流量及肾小球滤过率。结论　肾脏NO诱导利钠作用通过可溶性的鸟苷酸环化酶的激活以及cGMP产生。cGMP通过蛋白激酶G抑制肾小管钠的重吸收,与血流动力学改变无关。     

Repeatability of lung function tests during methacholine challenge in wheezy infants

BACKGROUND: The repeatability of lung function tests and methacholine inhalation tests was evaluated in recurrently wheezy infants over a one month period using the rapid thoracic compression technique. METHODS: Eighty-one wheezy, symptom free infants had pairs of methacholine challenge tests performed one month apart. Maximal flow at functional residual capacity (VmaxFRC) and transcutaneous oxygen tension (Ptco2) were measured at baseline and after methacholine inhalation. Provocative doses of methacholine causing a 15% fall in Ptco2 (PD15 Ptco2) or a 30% fall in VmaxFRC (PD30 VmaxFRC) were determined. RESULTS: Large changes in VmaxFRC were measured from T1 to T2 with a mean difference between measurements (T2-T1) of 7 (113) ml/s and a 95% range for a single determination for VmaxFRC of 160 ml/s. The mean (SD) difference between pairs of PD30 VmaxFRC measurements was 0.33 (1.89) doubling doses with a 95% range for a single determination of 2.7 doubling doses. Repeatability of PD15Ptco2 was similar. A change of 3.7 doubling doses of methacholine measured on successive occasions represents a significant change. CONCLUSIONS: Baseline VmaxFRC values are highly variable in wheezy, symptom free infants. Using either VmaxFRC or Ptco2 as the outcome measure for methacholine challenges provided similar repeatability. A change of more than 3.7 doubling doses of methacholine is required for clinical significance.