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.     

Real-time PCR assay for detection of fluoroquinolone resistance associated with grlA mutations in Staphylococcus aureus

Resistance to fluoroquinolones among clinical isolates of Staphylococcus aureus has become a clinical problem. Therefore, a rapid method to identify S. aureus and its susceptibility to fluoroquinolones could provide clinicians with a useful tool for the appropriate use of these antimicrobial agents in the health care settings. In this study, we developed a rapid real-time PCR assay for the detection of S. aureus and mutations at codons Ser-80 and Glu-84 of the grlA gene encoding the DNA topoisomerase IV, which are associated with decreased susceptibility to fluoroquinolones. The detection limit of the assay was 10 genome copies per reaction. The PCR assay was negative with DNA from all 26 non-S. aureus bacterial species tested. A total of 85 S. aureus isolates with various levels of fluoroquinolone resistance was tested with the PCR assay. The PCR assay correctly identified 100% of the S. aureus isolates tested compared to conventional culture methods. The correlation between the MICs of ciprofloxacin, levofloxacin, and gatifloxacin and the PCR results was 98.8%. The total time required for the identification of S. aureus and determination of its susceptibility to fluoroquinolones was about 45 min, including DNA extraction. This new rapid PCR assay represents a powerful method for the detection of S. aureus and its susceptibility to fluoroquinolones.     

Highly immunogenic and protective recombinant vaccine candidate expressed in transgenic plants

Vaccine development has been hampered by difficulties in developing new and safe adjuvants, so alternative technologies that offer new avenues forward are urgently needed. The goal of this study was to express a monoclonal recombinant immune complex in a transgenic plant. A recombinant protein consisting of a tetanus toxin C fragment-specific monoclonal antibody fused with the tetanus toxin C fragment was designed and expressed. Immune complex formation occurred between individual fusion proteins to form immune complex-like aggregates that bound C1q and FcgammaRIIa receptor and could be targeted to antigen-presenting cells. Unlike antigen alone, the recombinant immune fusion complexes were highly immunogenic in mice and did not require coadministration of an adjuvant (when injected subcutaneously). Indeed, these complexes elicited antibody titers that were more than 10,000 times higher than those observed in animals immunized with the antigen alone. Furthermore, animals immunized with only 1 mug of recombinant immune complex without adjuvant were fully protected against lethal challenge. This the first report on the use of a genetic fusion between antigen and antibody to ensure an optimal expression ratio between the two moieties and to obtain fully functional recombinant immune complexes as a new vaccine model.     

Six novel heterozygous MLH1, MSH2, and MSH6 and one homozygous MLH1 germline mutations in hereditary nonpolyposis colorectal cancer

Most hereditary nonpolyposis colorectal cancer (HNPCC) cases are caused by germline mutations of mismatch repair (MMR) genes (i.e., MLH1, MSH2, or MSH6). Here we describe six novel mutations in patients referred for genetic assessment. All of these mutations lead to premature translation termination. Five single base pair deletions lead to frameshift (MLH1: g.38-39insCCCA, g.1971del.T; MSH2: g.163del.C, g.746del.A; MSH6: g.3320del.A) and one nonsense mutation in MSH2 g.1030C>T leads to a stop codon: p.Q344X. In one patient, the previously described MLH1 nonsense mutation g.806C>G was found in a homozygous state. In this patient, the familial histories of both the mother and father suggested HNPCC syndrome. This patient developed colon cancer at 22 years of age, suggesting a more aggressive phenotype. The results of our study provide further insight into the mutational spectrum of MMR genes in HNPCC families.     

Expression and folding of an antibody fragment selected in vivo for high expression levels in Escherichia coli cytoplasm

In this review, we summarize some of our results on folding and directed evolution of an antibody fragment in Escherichia coli cytoplasm. We will also discuss some attempts to construct other antibodies active in this cellular compartment.     

Large Family With Maturity-Onset Diabetes of the Young and a Novel V121I Mutation in HNF4A

Maturity-onset diabetes of the young (MODY) is a subtype of early-onset diabetes mellitus which is characterized by autosomal dominant inheritance. Several genes are known to induce MODY : HNF4A/MODY1, GCK/MODY2, TCF1/MODY3, IPF1/MODY4, TCF2/MODY5 and NEUROD1/MODY6. We studied a Swiss family with 13 diabetic patients over 3 generations. The average age at diagnosis was 35 +/- 15 years (7 subjects before 30). In addition, 2 individuals had an abnormal oral glucose tolerance. The mutation present in this family was located in the DNA binding domain of HNF4A, a strongly conserved region across almost all species, and segregated in all the MODY patients. Identification of this missense mutation allowed for presymptomatic diagnosis in the younger generations and will improve medical follow-up of the predisposed individuals.     

Presence of a linear plasmid-like DNA molecule in the fungal pathogen Ceratocystis fimbriata Ell. & Halst.

Summary A plasmid-like molecule was detected in a strain of the ascomycete Ceratocystis fimbriata Ell. & Halst., a pathogenic fungus of Populus spp. The DNA replicon, designated pFQ501, was found to have a linear structure with a length of 6.0 kb (3.9 × 10⁶ daltons) and a density of 1.685 g/cc. This molecule was found to be associated with the mitochondria and was isolated from the gel; its restriction map was deduced from single and double digestions.     

Analysis of behavioral and hippocampal variation in congenic albino and pigmented BALB mice

Mice of the BALB/c strain are widely used in behavioral research in spite of the albino condition, which can obscure brain-behavior relationships. We have developed a pigmented BALB strain, congenic to BALB/c, which could be more appropriate for neurogenetic studies that aim at identifying the effects of neurological mutations on behavior. Comparison of inbred albino and pigmented congenic BALB arising from the same litters provides a valuable tool for detecting the consequences of the albino mutation on behavioral performances. Preliminary results presented here show that the albino condition does not interfere with the development and patterns of connectivity of mossy fibers in the hippocampus. On the other hand, obvious coat color-linked differences appear for locomotor activity and defecation scores in the open field, pigmented mice being unexpectedlyl less active and more reactive than albino, as if better vision increased their reactions to a novel, anxiogenic environment. Finally, pigmented mice do not show better performances in the radial maze, which confirms that the inability of BALB mice for spatial learning in a highly demanding version of this task cannot be attributed to their inability to process visual information.