P53 germline mutations in childhood cancers and cancer risk for carrier individuals

The family history of cancer in children treated for a solid malignant tumour in the Paediatric Oncology Department at Institute Gustave-Roussy, has been investigated. In order to determine the role of germline p53 mutations in genetic predisposition to childhood cancer, germline p53 mutations were sought in individuals with at least one relative (first- or second-degree relative or first cousin) affected by any cancer before 46 years of age, or affected by multiple cancers. Screening for germline p53 mutation was possible in 268 index cases among individuals fulfilling selection criteria. Seventeen (6.3%) mutations were identified, of which 13 were inherited and four were de novo. Using maximum likelihood methods that incorporate retrospective family data and correct for ascertainment bias, the lifetime risk of cancer for mutation carriers was estimated to be 73% for males and nearly 100% for females with a high risk of breast cancer accounting for the difference. The risk of cancer associated with such mutations is very high and no evidence of low penetrance mutation was found. These mutations are frequently inherited but de novo mutations are not rare. © 2000 Cancer Research Campaig

Influence of curing period and curing medium on corrosion, surface properties and compressive strength of concrete mixed with seawater

Water scarcity is one of the main problems faced by the world today. The Philippines is at risk of reaching the state of vulnerability in terms of the availability of freshwater. In every construction project, concrete curing is necessary. A significant amount of freshwater is needed to cure concrete. Thus, there is a need to find an alternative medium for curing concrete, such as seawater. This study reports the effects of curing period and curing medium on the concrete mixed with seawater to be able to evaluate the capability of seawater to be an alternative curing medium. The effects of seawater were determined through the corrosion, surface properties and compressive strength of the concrete mixed with seawater. The corrosion of the embedded steel bars in the rectangular specimens was tested every seven (7) days for four (4) months using the CT-7 (Corrosion Monitoring Test). The compressive strength of the cylindrical concrete specimens was evaluated using the ASTM C39 (Standard Test Method of Cylindrical Concrete Specimen). The data obtained for the surface properties were evaluated by observation. The data were interpreted by comparing the strength of the seawater cured (SWC) specimens and the freshwater cured (FWC) specimens. Curing the specimens in either freshwater or seawater does not have significant differences in either freshwater or seawater does not have significant difference in terms of its compressive strength and its corrosion current density until its 84th day. While in terms of corrosion potential, SWC specimens tend to have higher value only on the 2nd week of testing. However, from the results, it can be said that the corrosion potential on the early weeks of testing is still stabilizing. Seawater as a curing medium for CMSW can produce the same effect as freshwater curing on their 84th day, in terms of corrosion, compressive strength and surface properties, given that the specimens will only be cured for 7 days

Cloning and mapping of infA, the gene for protein synthesis initiation factor IF1.

The gene for translation initiation factor IF1, infA, has been identified by using two synthetic oligonucleotides to screen a Charon 30 library of Escherichia coli DNA. A recombinant lambda phage, C1921, was purified from a plaque positive for both probes. A 2.8 kb BglII fragment and a 2.0 kb HindIII fragment isolated from C1921 were subcloned into the BamHI and HindIII sites of pBR322 to yield pTB7 and pTH2 respectively. Synthesis of IF1 in maxicells transformed with pTB7 or pTH2 indicates the presence of inf A in both inserts. This was confirmed by DNA sequencing: a region was found that codes for a 8,119 dalton protein with an amino acid sequence corresponding to IF1. The chromosomal location of inf A was determined by mapping the closely linked beta-lactamase gene (Ampr) in pTB7 and pTH2. pTB7 and pTH2 were transformed into polA Hfr hosts, and integration of the plasmid by homologous recombination near inf A was selected on the basis of ampicillin resistance. The site of integration was confirmed by Southern blot analysis of restriction nuclease digested wild type and transformed genomic DNA. The Ampr marker (and therefore inf A) was mapped to about 20 minutes by Hfr interrupted matings and P1 transduction experiments. The structure and regulation of the inf A operon currently are being investigated