Persistence of antibody to hepatitis B surface antigen.

Sera from military personnel found to have antibodies to hepatitis B surface antigen (anti-HBS) in an epidemiological study of a hepatitis B outbreak were tested for persistence of that antibody 1 year later. Initially, 64% of the anti-HBS-positive sera reacted in passive hemagglutination tests with erythrocytes coated with hepatitis B surface antigen of both ayw and adw subtypes; the remaining sera reacted only with adw-coated erythrocytes (19%) or ayw-coated erythrocytes (17%). After 1 year, anti-HBS was detectable by passive hemagglutination tests in 87% of individuals with initial antibody to both subtypes but in only 41% and 16% (P less than 0.001) of those initially reacting only to adw- or ayw-coated erythrocytes, respectively. Seropositivity for anti-HBS correlated best with history of contact with jaundiced people (20.3%) and duty in Asia.     

抗SARS-CoV抗原的人源Fab段噬菌体抗体库的构建

目的 :利用抗SARS冠状病毒IgG抗体阳性的SARS康复患者外周血淋巴细胞 ,构建人源Fab段抗体文库。方法 :制备外周血淋巴细胞总RNA ,逆转录成cDNA。以其为模板 ,利用针对家族特异性Ig基因的引物扩增重链Fd段和轻链基因 ,并重组到噬菌粒载体pComb3中 ,将重组噬菌粒载体电转化大肠杆菌XL 1Blue,酶切鉴定抗体库的重组率 ,并测定噬菌体抗体库的库容量。结果 :构建了源于SARS康复患者血清中抗Fab段的抗体文库 ,轻链、重链Fd段基因的重组率分别为91%和 75 % ,库容量为 7.2 3× 10 7。结论 :成功地构建了抗SARS CoV抗原的人源Fab段噬菌体抗体库     

Selective media in the isolation of tubercle bacilli from tissues

Direct culture on Lowenstein-Jensen slopes and on three media made selective for tubercle bacilli by the addition of four antibacterial agents was compared with guinea-pig inoculation on 490 tissue specimens. Tubercle bacilli were obtained from 15 specimens by culture and 14 by guinea-pig inoculation; only one specimen was positive by guinea-pig and not by culture. The most efficient culture medium was a selective 7H11 slope. Routine guinea-pig inoculation has been replaced by a wider range of culture procedures.     

Clinical, genetic, and biochemical characterization of a Leber hereditary optic neuropathy family containing both the 11778 and 14484 primary mutations.

Four mitochondrial DNA (mtDNA) mutations at nps 3460, 11778, 14484, and 14459 account for roughly 90% of cases of Leber hereditary optic neuropathy (LHON) and are designated as "primary" LHON mutations since they act as major predisposition factors for LHON. Although each primary mutation can arise independently on different mtDNA backgrounds during human evolution, they characteristically do not co-occur in LHON patients. We report here a family with the simultaneous occurrence of the 11778A and 14484C mutations. Neuro-ophthalmological examination of the proband, a nine-year-old Caucasian female, revealed the bilateral optic atrophy, central scotomas, and reduced visual acuity typical of LHON. Her mother had normal appearing optic discs and is today visually asymptomatic. Analysis of the proband blood mtDNA revealed that she harbored both the 11778A (heteroplasmic, 94% mutant) and the 14484C (homoplasmic mutant) mutation. This genotype was maintained in proband lymphoblasts and transmitochondrial cybrids. The mother also had both mutations, with the 14484C mutation homoplasmic in all cell types examined. However, only 31% of her blood mtDNAs carried the 11778 mutation, which segregated to essentially 100% wild-type in lymphoblast and cybrid mtDNA. Complex I-linked respiration and specific enzyme activity were consistently lowest in proband lymphoblast and cybrid mitochondria compared to those from the mother, 11778A patients, 14484C patients, or controls, thus demonstrating both a deleterious synergistic interaction between the 11778A and 14484C mutations and the magnitude of 11778A-associated complex I dysfunction. Remarkably, spontaneous vision recovery occurred in the proband, highlighting the complexities encountered when associating mtDNA genotype and complex I function with LHON expression.     

Using a photon phase-space source for convolution/superposition dose calculations in radiation therapy

For a given linac design, the dosimetric characteristics of a photon beam are determined uniquely by the energy and radial distributions of the electron beam striking the x-ray target. However, in the usual commissioning of a beam from measured data, a large number of variables can be independently tuned, making it difficult to derive a unique and self-consistent beam model. For example, the measured dosimetric penumbra in water may be attributed in various proportions to the lateral secondary electron range, the focal spot size and the transmission through the tips of a non-divergent collimator; the head-scatter component in the tails of the transverse profiles may not be easy to resolve from phantom scatter and head leakage; and the head-scatter tails corresponding to a certain extra-focal source model may not agree self-consistently with in-air output factors measured on the central axis. To reduce the number of adjustable variables in beam modelling, we replace the focal and extra-focal sources with a single phase-space plane scored just above the highest adjustable collimator in a EGS/BEAM simulation of the linac. The phase-space plane is then used as photon source in a stochastic convolution/superposition dose engine. A photon sampled from the uncollimated phase-space plane is first propagated through an arbitrary collimator arrangement and then interacted in the simulation phantom. Energy deposition kernel rays are then randomly issued from the interaction points and dose is deposited along these rays. The electrons in the phase-space file are used to account for electron contamination. 6 MV and 18 MV photon beams from an Elekta SL linac are used as representative examples. Except for small corrections for monitor backscatter and collimator forward scatter for large field sizes (<0.5% with <20 x 20 cm2 field size), we found that the use of a single phase-space photon source provides accurate and self-consistent results for both relative and absolute dose calculations.     

先天性巨结肠患者人类巨细胞病毒UL144基因多态性的研究

目的研究人类巨细胞病毒（human cytomegalovirus,HCMV）UL144基因在先天性巨结肠（Hirschsprung＇s disease,HD）临床株中的多态性,探讨HCMV UL144基因多态性与致病性之间的关系.方法随机选取53个先天性巨结肠患儿痉挛段结肠手术标本及经荧光定量PCR方法检测HCMV DNA为阳性的4个HD患儿的尿标本,对照组为无症状或仅有皮肤轻度黄疸的6个尿标本.应用巢式聚合酶链反应的方法,扩增HCMV UL144基因开放阅读框架（ORF）,扩增阳性的临床株进行双向DNA测序,最后通过DNAclub、Bioedit、DNAstar、GeneDoc等软件进行分析.结果23份HD痉挛段肠组织（46%）及4份尿标本HCMV UL144基因扩增阳性,并且完成测序.种系进化树分析结果显示25个HD患儿的DNA序列分为3个基因型,G1A型64.0%,G2型24%,G3型12%.与对照组比较,经χ^2检验,χ^2=10.93,P为0.012;其中HD临床株G1A和G3型基因经Fisher检验,P为0.015,差异具有统计学意义.全结肠型、长段型及普通型HD分散分布于UL144各个基因型中.结论HD与HCMV感染有关,HCMV可能是HD的病因之一;在HD患儿中,HCMV感染以UL144基因G1A型为主;HD的临床分型与HCMV UL144基因分型无关.     

Characterization of Sm13, a tegumental antigen of Schistosoma mansoni

Sm13, a 13-kDa Schistosoma mansoni tegumental antigen, is one of the principal polypeptides recognized by antibodies from mice protectively vaccinated with adult-worm tegumental membranes. To obtain the complete gene encoding Sm13 we subcloned and sequenced a cDNA and a fragment of a genomic clone. The collated sequence contains 1088 nucleotides and represents the full-length open reading frame of the gene, encoding a protein of 104 amino acids with a calculated molecular mass of 11,923 Da, compatible with the native protein identified in the tegumental membranes. The sequence derived from genomic DNA contains a 45-nucleotide intron. The analysis of the predicted protein suggests the presence of both N- and C-terminal hydrophobic membrane-spanning segments, and the coding region contains no homology in the currently available data bases. Additionally, the coding region is preceded by putative CCAAT and TATA boxes that may be involved in the control of expression. Western-blot analysis and indirect immunofluorescence resulted in the identification of a 13-kDa protein (Sm13) in the tegument of adult worms. The present study reveals that Sm13 behaves as an integral membrane protein upon partitioning in Triton X-114 and that it is present in worms of 3 weeks or older but not in schistosomula or miracidia. Moreover, it is also specifically recognized by sera from some schistosomiasis patients in enzyme-linked immunosorbent assay and Western-blot analysis, suggesting that it is immunogenic in human schistosomiasis. Received: 17 February 2000 / Accepted: 22 March 2000     

Lysosomal routing of Fc gamma RI from early endosomes requires recruitment of tyrosine kinases.

The high-affinity receptor for immunoglobulin G (Fc gamma RI) plays a central role in the clearance of immune complexes by mediating their internalization and delivery to lysosomes. In monocytic U937 cells, receptor internalization is independent of tyrosine kinase activity. However, the tyrosine kinase inhibitor, genistein, prevents further progress of the receptor to lysosomes and traps it in a sub-plasma membrane early endosome. Similarly, Fc gamma RI expressed in COS cells is able to internalize immune complexes but is unable to translocate to lysosomes. This suggests that Fc gamma RI, whose cytoplasmic tail is devoid of known signalling motifs, must recruit tyrosine kinases via its gamma-chain to achieve lysosomal delivery. We show that a chimera of the extracellular domain of Fc gamma RI and the cytoplasmic tail of the gamma-chain is both internalized and efficiently trafficked to lysosomes. Our study suggests that a key function of the gamma-chain is recruitment of tyrosine kinases to initiate the intracellular signalling pathways required to target Fc gamma RI following immune complex aggregation to lysosomes and not to initiate endocytosis per se.     

Terminal-Phase Chronic Myelogenous Leukemia: Approaches to Treatment

The prognosis of patients with CML has improved little in the past 50 years. The relatively benign chronic phase invariably deteriorates to a refractory and rapidly fatal terminal phase. This terminal stage has been found to have two major subtypes as defined by morphologic, cytochemical, immunologic, and enzymatic criteria--myeloblastoid and lymphoblastoid. Aggressive combination chemotherapy has achieved minimal improvement in survival once the terminal phase has begun, perhaps because only Ph1-positive stem cells remain to repopulate the marrow at this stage. Bone marrow transplantation has also been unsuccessful as therapy for the terminal phase, possibly because the patients are too debilitated to tolerate transplantation once the terminal phase has begun. Combination chemotherapy has been applied in an effort to eliminate the Ph1 chromosome-containing clone during the chronic phase. This goal has not yet been consistently achieved. Chemotherapy has also not been able to delay the onset of the terminal phase nor to prolong survival. Even in those patients in whom the Ph1 chromosome-containing clone has been eliminated, relapse to the chronic phase with return of the Ph1 chromosome has generally occurred within a brief period of time. Bone marrow transplantation during the chronic phase may hold the promise of true cure for CML, with permanent elimination of the malignant clone. However, the chronic phase can be unpredictably long and patients in the chronic phase often have few, if any symptoms. Therefore, there has been a reluctance to employ drastic therapy during the chronic phase. Techniques to predict the transformation to the terminal phase prior to overt morphologic or clinical conversion are now being developed. It may be possible in the future to attempt HLA-matched sibling donor bone marrow transplantation at the earliest signs of transformation from the chronic to the terminal phase. In this manner, optimal survival might be achieved by allowing patients to be maintained in the chronic phase for as long as possible prior to the initiation of aggressive therapy. Until this is routinely possible, continued research designed to improve the therapy of the terminal phase must be pursued. These attempts are likely to include the development and evaluation of new chemotherapeutic agents, novel methods of administration of existing drugs to better exploit their pharmacokinetics (for example, continuous infusion), and the utilization of newly described treatment approaches (such as the use of "differentiating" agents in an attempt to prevent progression to blastic transformation).(ABSTRACT TRUNCATED AT 400 WORDS)