Centromere-telomere (12;8p) fusion, telomeric 12q translocation, and i(12p) trisomy

The concurrence of a short arm isochromosome and a translocation of the entire long arm of the same chromosome to a telomere of another chromosome, implying trisomy for 4p, 5p, 7p, 9p, 10p or 12p, has been described in 13 patients. We have now used fluorescence in situ hybrization (FISH) to better characterize one of these rearrangements in which 12q was translocated to 8pter, whereas 12p was converted into an isochromosome. An alphoid centromere-12 repeat gave a strong signal on the i( 2p) and a weak but distinct signal at the breakpoint junction of the der(8), whereas the pantelomeric probe revealed three clear hybridization sites on the der(8): one at each end and another at the breakpoint junction. These findings suggest that the prime event was a post-fertilization centric fission of chromosome 12 leading to the 12q translocation via a real centromere telomere fusion and the i(12p). Alternatively, the crucial event may have been a centromere telomere recombination. An interstitial telomere has been documented by means of FISH at the breakpoint junction of the sole derivative usually present in 20 constitutional translocations including eight with a jumping behavior. In addition, six other telomeric translocations defined by banding methods, including another case of 12q translocation/i(12p), have also been jumping ones. These telomeric translocations have been de noro events and their proneness to exhibit a jumping behavior appears to be independent of the involved chromosomes, size of the translocated segments, and concomitant abnormalities.     

ABCC10, ABCC11, and ABCC12

Multidrug resistance protein (MRP)7, MRP8, and MRP9 (gene symbols ABCC10, ABCC11, and ABCC12) are recently identified members of the MRP family that are at relatively early stages of investigation. Of these proteins, a physiological function has only been established for MRP8, for which a single nucleotide polymorphism determines wet vs dry earwax type. MRP7 and MRP8 are lipophilic anion pumps that are able to confer resistance to chemotherapeutic agents. MRP7 is competent in the transport of the glucuronide E₂17βG, and its resistance profile, which includes several natural product anticancer agents, is distinguished by the taxane docetaxel. MRP8 is able to transport a diverse range of lipophilic anions, including cyclic nucleotides, E₂17βG, steroid sulfates such as dehydroepiandrosterone (DHEAS) and E₁S, glutathione conjugates such as leukotriene C4 and dinitrophenyl-S-glutathione, and monoanionic bile acids. However, the constituent of earwax that is susceptible to transport by MRP8 has not been identified. MRP8 has complex interactions with its substrates, as indicated by the nonreciprocal ability of DHEAS to stimulate E₂17βG transport. Similar to the case for other MRPs that possess only two membrane spanning domains (MRP4 and MRP5), MRP8 is a cyclic nucleotide efflux pump that is able to confer resistance to nucleoside-based agents, such as PMEA and 5FU. The functional characteristics of MRP9 are currently unknown.     

Abstracts vol 12, issue 2, 1994

Chinese Journal Of Clinical Anatomy

Abstracts vol 12, issue 2, 1994     

Improved method for measuring vitamin B12 in serum using intrinsic factor, 57CoB12, and coated charcoal

An improved and simplified method is described for the measurement of vitamin B(12) in serum using intrinsic factor, (57)CoB(12), and coated charcoal. The extraction of serum in the presence of cyanide and the incorporation of B(12)-deficient serum into the intrinsic factor control has increased the accuracy of the method for both sera and crystalline B(12) solutions. There are interesting differences between the results obtained for some sera by the isotope and L. leichmannii methods and the reasons for these differences are discussed.     

Ovarian follicular concentration of IL-12, IL-15, IL-18 and p40 subunit of IL-12 and IL-23

BACKGROUND: The aim of the study was to determine the presence of interleukin (IL)-12, IL-15, IL-18 and p40 subunit of IL-12/IL-23 in follicular fluid from spontaneous cycles and the relation between the concentration of selected cytokines and IVF-embryo transfer outcome. METHODS: IVF-embryo transfer and enzyme immunoassay (EIA) (R&D Systems, Minneapolis, MN, USA and MBL, Nagoya, Japan) were used. RESULTS: Follicular fluid of women included in the IVF-embryo transfer procedure contained common p40 subunit of IL-12/IL-23 (median 70.1 pg/ml), IL-15 (median 1.3 pg/ml) and IL-18 (median 38.2 pg/ml). There was a significant negative correlation between follicular fluid concentrations of IL-15 and IL-18 (R=-0.392, P=0.003). Significantly higher concentrations of common p40 subunit of IL-12/IL-23 (median 79.8 pg/ml) were found in the follicular fluid taken from follicles containing oocytes, when compared with those without an oocyte (median 44.5 pg/ml, P=0.006). Patients who achieved clinical pregnancy had significantly decreased concentration of IL-15 (median 0.8 pg/ml) compared with patients without successful IVF-embryo transfer outcome (median 1.4 pg/ml, P=0.047). CONCLUSION: Follicular fluid collected from spontaneous cycles contains detectable levels of p40 subunit of IL-12/IL-23, IL-15 and IL-18. Increased concentrations of p40 subunit of IL-12/IL-23 in follicles containing oocytes suggest an important role of this cytokine in reproduction. Possible negative value of IL-15 as a predictor of IVF-embryo transfer success remains to be determined.