Jumping translocations in multiple myeloma

Jumping translocations (JT) have been defined as nonreciprocal translocations involving a same donor chromosome arm or chromosome segment onto two or more recipient chromosomes in different cell lines in the same patient, leading to a mosaic karyotype. This definition has been expanded to also include extra copies of a same donor segment on different recipient chromosomes in a single clone. Six patients with multiple myeloma and JT involving chromosome arm 1q were identified among 37 patients presenting with chromosome 1 abnormalities. All six patients had an advanced disease and a short survival. The literature review allowed us to identify 24 additional patients with JT. Chromosomes 16 and 19 were the recipients in 11 (45.8%) and 6 (25%) of these 24 patients, respectively. Breakpoints on the recipient chromosomes were pericentromeric in 46.2% and telomeric in 40.4% of the breakpoints recorded. Since telomeres are made of (TTAGGG)n tandem DNA repeats that are also found in the pericentromeric heterochromatic regions (interstital telomeric sequences), it is presumed that jumping translocations arise through illegimate recombination between telomere repeat sequences and interstitial telomeric sequences.     

Expression of ATM, p53, and the MRE11-Rad50-NBS1 complex in myoepithelial cells from benign and malignant proliferations of the breast

AIMS: To analyse the expression of proteins involved in DNA double strand break detection and repair in the luminal and myoepithelial compartments of benign breast lesions and malignant breast tumours with myoepithelial differentiation. METHODS: Expression of the ataxia telangiectasia (ATM) and p53 proteins was immunohistochemically evaluated in 18 benign and malignant myoepithelial tumours of the breast. Fifteen benign breast lesions with prominent myoepithelial compartment were also evaluated for these proteins, in addition to those in the MRE11-Rad50-NBS1 (MRN) complex, and the expression profiles were compared with those seen in eight independent non-cancer (normal breast) samples and in the surrounding normal tissues of the benign and malignant tumours examined. RESULTS: ATM expression was higher in the myoepithelial compartment of three of 15 benign breast lesions and lower in the luminal compartment of eight of these lesions compared with that found in the corresponding normal tissue compartments. Malignant myoepithelial tumours overexpressed ATM in one of 18 cases. p53 was consistently negative in benign lesions and was overexpressed in eight of 18 malignant tumours. In benign breast lesions, expression of the MRN complex was significantly more reduced in myoepithelial cells (up to 73%) than in luminal cells (up to 40%) (p=0.0005). CONCLUSIONS: Malignant myoepithelial tumours rarely overexpress ATM but are frequently positive for p53. In benign breast lesions, expression of the MRN complex was more frequently reduced in the myoepithelial than in the luminal epithelial compartment, suggesting different DNA repair capabilities in these two cell types.     

Novel immunofluorescence assay using recombinant nucleocapsid-spike fusion protein as antigen to detect antibodies against severe acute respiratory syndrome coronavirus

Severe acute respiratory syndrome (SARS) is caused by a novel and highly infectious virus named SARS coronavirus (SARS-CoV). Among the serological tests currently available for the detection of SARS-CoV, a whole-virus-based immunofluorescence assay (IFA) was considered one of the most sensitive assays and served as a "gold standard" during the SARS epidemic in Singapore in 2003. However, the need to manipulate live SARS-CoV in the traditional IFA limits its wide application due to the requirement for a biosafety level 3 laboratory and the risk of laboratory infection. Previously, we have identified two immunodominant epitopes, named N195 and Sc, in the two major structural proteins, the N and S proteins, of SARS-CoV (Q. He, K. H. Chong, H. H. Chng, B. Leung, A. E. Ling, T. Wei, S. W. Chan, E. E. Ooi, and J. Kwang, Clin. Diagn. Lab. Immunol., 11:417-422, 2004; L. Lu, I. Manopo, B. P. Leung, H. H. Chng, A. E. Ling, L. L. Chee, E. E. Ooi, S. W. Chan, and J. Kwang, J. Clin. Microbiol. 42:1570-1576, 2004). In the present study, the N195-Sc fusion protein was highly expressed in insect (Sf9) cells infected with a recombinant baculovirus bearing the hybrid gene under the control of a polyhedrin promoter. An IFA based on Sf9 cells producing the fusion protein was standardized with 23 serum samples from patients with SARS, 20 serum samples from patients with autoimmune diseases, and 43 serum samples from healthy blood donors. The detection rates were comparable to those obtained with a commercial SARS-CoV IFA kit (EUROIMMUN, Gross Groenau, Germany) and a conventional IFA performed at the Singapore General Hospital. Our data showed that the newly developed IFA could detect SARS-CoV in 22 of the 23 SARS-CoV-positive serum samples and gave no false-positive results when the sera from patients with autoimmune diseases and healthy individuals were tested. The detection rate was identical to those of the two whole-virus-based IFAs. Thus, the novel N-S fusion antigen-based IFA could be an attractive alternative to present whole-virus-based IFAs for the diagnosis of SARS-CoV infection.     

人乳头瘤病毒18型L1-E6、L1-E7嵌合基因表达载体的构建及表达

目的 构建HPV 18 L1－E6，L1－E7嵌合基因的表达载体，并在CHO细胞中表达。方法 克隆HPV18 L1－E6和L1－E7基因，插入中介载体pGEMT-Easy中并测序鉴定。采用PCR定点突变法，突变L1－E6，L1－E7基因序列中与转化作用相关的位点，分别与L1基因连接后插入真核表达载体pVAX1，构建真核表达质粒pVAX-1L1 E6Mxx,L1E7Mxx。用磷酸钙沉淀法，转染CHO细胞，以抗HPV－18L1，抗E6和抗E7特异性单克隆抗体（mAb)做ELISA和免疫细胞化学法检测。结果 ELISA检测显示，转染各种pVAX1-LIE6Mxx-L1E7Mxx融合蛋白表达质粒的细胞提取物的P－N值均＞2．1；免疫细胞化学检测，在胞浆，胞核可见棕黄色颗粒。结论 我建的pVAX1-L1E6Mxx-E7Mxx融合蛋白质表达质粒，可在转当细胞内表达相应的L1－E6Mxx和L1－E7Mxx蛋白，为今后进行DNA疫苗的研究奠定了基础。     

Validation of an ELISA for the diagnosis of recent Campylobacter infections in Guillain–Barré and reactive arthritis patients

Weeks or months following Campylobacter infection, a small proportion of infected individuals develop Guillain-Barré syndrome (GBS) or reactive arthritis (ReA). Stool culture for Campylobacter is often negative in these patients, and serology is therefore the method of choice for diagnosing a recent infection with Campylobacter. This study developed a capture ELISA system to detect anti-Campylobacter IgA and IgM antibodies indicative of a recent infection. The sensitivity of the assay was 82.0% in uncomplicated Campylobacter enteritis patients, 96.2% in GBS patients who were culture-positive for Campylobacter, and 93.1% in culture-positive ReA patients, with a specificity of 93.0%. The assay allows identification of Campylobacter infection in patients with post-infectious neurological and rheumatological complications.     

<Emphasis Type="Italic">Trypanosoma evansi</Emphasis> in inbred and Swiss-Webster mice: distinct aspects of pathogenesis

Trypanosoma evansi (Trypanosomatidae, Kinetoplastida) is a salivarian trypanosomatid that infects eight mammal orders spread over America, Europe and Asia. In Brazil, T. evansi is the etiological agent of Mal de Cadeiras, a horse disease very often described in the region known as Pantanal do Mato Grosso. Few data concerning the genetic diversity and biology of subpopulations of T. evansi that circulate in Brazil are available. The factors that modulate the interaction of this parasite with its hosts also remain to be elucidated. Here we evaluated the course of experimental infection of six T. evansi isolates derived from domestic and wild animals in Swiss-Webster mice and three Mus musculus lineages. The follow-up included biological, immunological as well as biochemical and hematological parameters. The same isolates as well as three others were characterized by pulsed-field electrophoresis. Our results showed that T. evansi isolates displayed significant differences regarding behavior and morbidity patterns in the distinct mouse lineages. Nevertheless, these differences could not be correlated with pulsed-field electrophoresis profiles. Indeed, concerning this molecular marker, only microheterogeneity was observed. Moreover, we observed that the outcome of the infection is defined by both host genetic background and peculiarities (virulence factors) of the distinct T. evansi isolates. Anemia and hypoglycemia were the only features that could be observed in all mouse lineages, independently of the inoculated T. evansi subpopulation. In addition, our data also show that Mus musculus is a suitable model host for the study of the different pathogenetic features of T. evansi infection.     

Hypoxia can contribute to the induction of the Epstein-Barr virus (EBV) lytic cycle.

BACKGROUND: Like other herpes viruses, latent Epstein-Barr virus (EBV) infection can be reactivated to lytic replication. Reactivation can be achieved by treatment with various reagents, including tetradecanoyl phorbol acetate (TPA) and Ca2+ ionophores. Relatively little is known about the physiological factors related to reactivation of EBV. Previous studies have demonstrated that G0/G1 cell cycle arrest is associated with EBV activation, and that hypoxic conditions can induce cell cycle arrest. In the present study we investigated the effect of hypoxia on reactivation of EBV. OBJECTIVE AND METHODS: Hypoxic culture conditions were established and the expression of Zta protein and the number of EBV DNA copies were measured in B95-8 cells maintained under these conditions. RESULTS: Hypoxia treatment not only increased the expression of the EBV immediate-early protein Zta (which mediates the switch between the latent and lytic form of infection), but also increased the number of EBV DNA copies in B95-8 cells. CONCLUSIONS: EBV in latent infection can be activated to lytic infection by hypoxia treatment.     

Predicting HIV-1 coreceptor usage with sequence analysis

Bioinformatics approaches are increasingly being used to identify and understand the genetic variation underlying changes in HIV-1 biological phenotype. The variable regions of the viral envelope are the major determinant of virus coreceptor usage and cell tropism. Specifically, amino acids 11 and 25 in the 3rd variable (V3) loop have been found to strongly influence viral syncytium inducing capacity and coreceptor usage. Many additional V3 loop changes, however, as well as changes elsewhere in Env, are thought to contribute to phenotype. In this review we describe several recently developed methods to analyze this variability and their use to predict biological phenotype based on sequence information. These approaches have identified changes in the V3 loop, in addition to the known changes at positions 11 and 25, that affect phenotype and significantly enhance our ability to predict phenotype from genotype. Besides improving phenotype prediction, methods that score V3 sequences on a continuous scale can also assist in the interpretation of evolutionary information about shifts in phenotype, and the relationship between that evolution and pathogenesis. Several examples and potential practical applications of this scoring are discussed. We conclude that advances in computational approaches have enhanced both our ability to predict and to understand HIV-1 biological phenotype evolution. Further development of these methods, by extending analysis to regions outside the V3 loop and to clades beyond subtype B, will extend our understanding of HIV-1 pathogenesis and inform treatment strategies.     

Oligoclonal interspecific origin of ‘North Indian’ and ‘Chinese’ sugarcanes

Sugarcanes consist of several groups of complex polyploid forms. The origin of North Indian and Chinese sugarcanes (referred to as S. barberi and S. sinense) was investigated using genomic in-situ hybridization (GISH), detection of species-specific repeated sequences and RFLP. GISH proved their interspecific hybrid origin. Together with the distribution of species-specific repeated sequences and earlier RFLP data, the results show that both taxa are derived from interspecific hybridization between S. officinarum and S. spontaneum and that no other genus has been directly involved. RFLP indicates that the clones are clustered into a few groups, each derived from a single interspecific hybrid that has subsequently undergone a few somatic mutations. These groups correspond quite well with those already defined based on morphological characters and chromosome numbers. However, the calculated genetic similarities do not support the existence of two distinct taxa. The North Indian and Chinese sugarcanes represent a set of horticultural groups rather than established species.