Cardiovascular disease mortality in Canada.

During the past two decades approximately one half of all deaths in Canada were due to cardiovascular diseases. Ischemic heart disease and cerebrovascular disease caused more than 60% and 20% of those deaths respectively. The mortality rates for ischemic heart disease in males increased slightly until 1965 and then dropped substantially, whereas the rates for females, which were declining at least since the early 1960s, accelerated in their decline. As a consequence, the rates for males remain almost twice as high as those for females. The reductions were initially observed in males 25 to 34 years old and in all age groups of females, but became apparent in a wider range of ages in the second period reviewed (1969 through 1977). The mortality of cerebrovascular disease has gradually diminished for both sexes since the 1950s, but the decline has been more pronounced among females, who originally had the higher rate. Marked geographic differences in mortality rates still exist in Canada despite the decline in death rates for both ischemic heart disease and cerebrovascular disease in all regions of the country. Surprising regional differences in times of onset of these declines have been demonstrated. For ischemic heart disease Ontario maintains the highest and the Prairies the lowest mortality rates. Quebec, despite a sustained decline, still ranks third, while the Pacific region shows the second-lowest rates in the country. The Atlantic region showed the lowest rates of decline in the period reviewed. The reduction in the mortality of ischemic heart disease in Canada (16.4% between 1969 and 1977) must be considered real for a variety of reasons. Direct evidence is not available to elucidate whether the reduction is the consequence of reduced incidence, increased survival or a combination of the two factors. The potential role of various factors that may have contributed to this decline is briefly discussed in this article.     

Establishment and maintenance of human embryonic stem cell lines on human feeder cells derived from uterine endometrium under serum-free condition

Human embryonic stem (hES) cells are usually established and maintained on mouse embryonic fibroblast (MEFs) feeder layers. However, it is desirable to develop human feeder cells because animal feeder cells are associated with risks such as viral infection and/or pathogen transmission. In this study, we attempted to establish new hES cell lines using human uterine endometrial cells (hUECs) to prevent the risks associated with animal feeder cells and for their eventual application in cell-replacement therapy. Inner cell masses (ICMs) of cultured blastocysts were isolated by immunosurgery and then cultured on mitotically inactivated hUEC feeder layers. Cultured ICMs formed colonies by continuous proliferation and were allowed to proliferate continuously for 40, 50, and 55 passages. The established hES cell lines (Miz-hES-14, -15, and -9, respectively) exhibited typical hES cells characteristics, including continuous growth, expression of specific markers, normal karyotypes, and differentiation capacity. The hUEC feeders have the advantage that they can be used for many passages, whereas MEF feeder cells can only be used as feeder cells for a limited number of passages. The hUECs are available to establish and maintain hES cells, and the high expression of embryotrophic factors and extracellular matrices by hUECs may be important to the efficient growth of hES cells. Clinical applications require the establishment and expansion of hES cells under stable xeno-free culture systems.     

Insulation and wiring specificity of BceR‐like response regulators and their target promoters in Bacillus subtilis

BceRS and PsdRS are paralogous two‐component systems in Bacillus subtilis controlling the response to antimicrobial peptides. In the presence of extracellular bacitracin and nisin, respectively, the two response regulators (RRs) bind their target promoters, P_bceA or P_psdA, resulting in a strong up‐regulation of target gene expression and ultimately antibiotic resistance. Despite high sequence similarity between the RRs BceR and PsdR and their known binding sites, no cross‐regulation has been observed between them. We therefore investigated the specificity determinants of P_bceA and P_psdA that ensure the insulation of these two paralogous pathways at the RR–promoter interface. In vivo and in vitro analyses demonstrate that the regulatory regions within these two promoters contain three important elements: in addition to the known (main) binding site, we identified a linker region and a secondary binding site that are crucial for functionality. Initial binding to the high‐affinity, low‐specificity main binding site is a prerequisite for the subsequent highly specific binding of a second RR dimer to the low‐affinity secondary binding site. In addition to this hierarchical cooperative binding, discrimination requires a competition of the two RRs for their respective binding site mediated by only slight differences in binding affinities.     

Identification of lucerne stem cell wall traits related to in vitro neutral detergent fibre digestibility

Genetic improvement of forage digestibility, especially utilizing marker assisted selection and recombinant DNA techniques, requires identification of specific biochemical traits and associated genes that impact digestibility. We undertook a study to identify cell wall (CW) traits of lucerne (Medicago sativa L.) stems that were consistently and strongly correlated with in vitro neutral detergent fibre (NDF) digestibility, a measurement that has been shown to correlate with animal performance. Spring and summer harvested lucerne stem material, for 2 years, from 24 individual plants in each of two germplasm sources were analyzed for 16 and 96 h in vitro NDF digestibility, and cell wall concentration and composition (monosaccharide constituents of cellulose, hemicellulose, and pectin; and Klason lignin (KL)) by the Uppsala dietary fibre method using near-infrared reflectance spectroscopy (NIRS). Pearson correlation coefficients were calculated for the relationships among these cell wall traits and with in vitro NDF digestibility. Concentrations of the pectin monosaccharide components were all negatively correlated (r=−0.73 to −0.94) with total cell wall concentration. In contrast, the three most abundant cell wall components glucose (Glc), xylose (Xyl) and Klason lignin were not correlated, or only weakly positively correlated (r<0.35), with cell wall concentration. Cell wall concentration was consistently negatively correlated (r=−0.60 to −0.94) with both 16 and 96 h in vitro NDF digestibility. In contrast, Klason lignin concentration was only marginally correlated (r<0.30) with 16 h in vitro NDF digestibility, but strongly negatively correlated (r=−0.71 to −0.74) with 96 h in vitro NDF digestibility. This is consistent with previous reports which show that lignin affects potential extent of digestion, but not rate. Cell wall glucose and xylose concentrations were inconsistently correlated with fibre digestibility. The monosaccharide components of pectin were consistently positively correlated (r=0.54–0.90) with in vitro NDF digestibility, except for 96 h in vitro NDF digestibility of spring harvested stems. Growth environment (year) and germplasm source had only minor impacts on the preceding correlation patterns, whereas spring versus summer harvests accounted for the inconsistencies observed among correlations for cell wall traits. The results of this study indicate that genetic improvement of fibre digestibility of lucerne stems should target genes that reduce total cell wall concentration, perhaps by reducing the rate of xylem tissue deposition during maturation, and reduce Klason lignin and increase pectin concentrations in the cell wall to improve potential extent and rate of fibre digestibility, respectively.     

Kinetic Monte Carlo simulation for the striation distribution of void defects in Czochralski silicon growth

Unique crystal-originated pit (COP) distribution, similar to a striation pattern, is well matched with the oxygen profile in experimental analysis. It shows the strong relationship between oxygen concentration and COP distribution. In this paper, we study the generation of void defects and the relationship between interstitial oxygen and vacancy using the kinetic lattice Monte Carlo (KLMC) method. The KLMC method has been applied extensively in various forms to the study of micro-defects in silicon wafers. It explained well the formation of void defects such as vacancy–oxygen complex and vacancy–vacancy complex. The formation of clusters is strongly affected by oxygen concentration, which showed the relationship between COP distribution and oxygen concentration. The unique COP distribution could be correctly explained with KLMC results, and this kind of meso-scale results has not yet been reported.     

Comparison of PERV genomic locations between Asian and European pigs

Xenotransplantation from pigs provides a possible solution to the shortage of human organs for allotransplantation. Porcine endogenous retroviruses (PERVs) are a possible obstacle to using porcine organs in addition to the immunological barriers. Three main types of PERVs (A, B and C) have been previously investigated in diverse pig breeds. To examine the copy numbers of PERVs and their genomic locations in the Korean native pig genome, we screened a BAC (Bacterial Artificial Chromosome) library with PERV-specific protease primers for initial recognition of PERV-positive clones and three sets of envelope-specific primers for the identification of PERV types. A total of 45 PERV-positive clones, nine PERV-A and 36 PERV-B, have been identified from the library screening and the BAC contigs were constructed using the primers designed from BAC end sequences (BESs). These primers were also used for SCH (Somatic Cell Hybrid) and RH (Radiation Hybrid) mapping of the PERV-positive clones. The results indicate that 45 PERV-positive BAC clones belong to nine contigs and a singleton. SCH and IMpRH (INRA-Minnesota Porcine Radiation Hybrid) mapping results indicated that there are at least eight separate PERV genomic locations, consisting of three PERV-A and five PERV-B. One contig could not be mapped, and two contigs are closely located on SSC7. Southern blotting indicates there may be up to 15 additional sites. Further investigation of these clones will contribute to a general strategy to generate PERV-free lines of pigs suitable for xenotransplantation.     

CCL5/CCR5 axis promotes the motility of human oral cancer cells

CCL5 (previously called RANTES) is in the CC‐chemokine family and plays a crucial role in the migration and metastasis of human cancer cells. On the other hand, the effect of CCL5 is mediated via CCR receptor. RT‐PCR and flow cytometry studies demonstrated CCR5 but not CCR1 and CCR3 mRNA in oral cancer cell lines, especially higher in those with high invasiveness (SCC4) as compared with lower levels in HSC3 cells and SCC9 cells. Stimulation of oral cancer cells with CCL5 directly increased the migration and metalloproteinase‐9 (MMP‐9) production. MMP‐9 small interfering RNA inhibited the CCL5‐induced MMP‐9 expression and thereby significantly inhibited the CCL5‐induced cell migration. Activations of phospholipase C (PLC), protein kinase Cδ (PKCδ), and NF‐κB pathways after CCL5 treatment was demonstrated, and CCL5‐induced expression of MMP‐9 and migration activity was inhibited by the specific inhibitor of PLC, PKCδ, and NF‐κB cascades. In addition, migration‐prone sublines demonstrate that cells with increasing migration ability had more expression of MMP‐9, CCL5, and CCR5. Taken together, these results indicate that CCL5/CCR5 axis enhanced migration of oral cancer cells through the increase of MMP‐9 production. J. Cell. Physiol. 220: 418–426, 2009. © 2009 Wiley‐Liss, Inc.     

Heterotic patterns in rapeseed (<Emphasis Type="Italic">Brassica napus</Emphasis> L.): I. Crosses between spring and Chinese semi-winter lines

Chinese semi-winter rapeseed is genetically diverse from Canadian and European spring rapeseed. This study was conducted to evaluate the potential of semi-winter rapeseed for spring rapeseed hybrid breeding, to assess the genetic effects involved, and to estimate the correlation of parental genetic distance (GD) with hybrid performance, heterosis, general combining ability (GCA) and specific combining ability (SCA) in crosses between spring and semi-winter rapeseed lines. Four spring male sterile lines from Germany and Canada as testers were crossed with 13 Chinese semi-winter rapeseed lines to develop 52 hybrids, which were evaluated together with their parents and commercial hybrids for seed yield and oil content in three sets of field trials with 8 environments in Canada and Europe. The Chinese parental lines were not adapted to local environmental conditions as demonstrated by poor seed yields per se. However, the hybrids between the Chinese parents and the adapted spring rapeseed lines exhibited high heterosis for seed yield. The average mid-parent heterosis was 15% and ca. 50% of the hybrids were superior to the respective hybrid control across three sets of field trials. Additive gene effects mainly contributed to hybrid performance since the mean squares of GCA were higher as compared to SCA. The correlation between parental GD and hybrid performance and heterosis was found to be low whereas the correlation between GCA_{(f + m)} and hybrid performance was high and significant in each set of field trials, with an average of r = 0.87 for seed yield and r = 0.89 for oil content, indicating that hybrid performance can be predicted by GCA_{(f + m)}. These results demonstrate that Chinese semi-winter rapeseed germplasm has a great potential to increase seed yield in spring rapeseed hybrid breeding programs in Canada and Europe.     

An improved transformation protocol for studying gene expression in hairy roots of sugar beet (Beta vulgaris L.)

A transformation protocol, based on co-inoculation with two strains of Agrobacterium, Agrobacterium tumefaciens LBA4404 and A. rhizogenes 15834 containing a binary vector with the GUS gene, was established for the induction of transgenic hairy roots from sugar beet (Beta vulgaris L.) explants. It resulted in marked improvement in the formation of hairy roots and the integration of the binary vector T-DNA into the host genome. Of 250 inoculated sugar beet hypocotyls, 84% yielded hairy roots 5–7 days after inoculation, of which 70% were co-transformed with the binary vector T-DNA. To determine stable expression of alien genes in hairy roots, the nematode resistance gene Hs1 ^pro-1 was used as a reporter gene. In addition, molecular marker analysis was applied to monitor stable incorporation of a translocation from the wild beet B. procumbens. The molecular analysis and the nematode (Heterodera schachtii) resistance test in vitro demonstrated that the genomic structure and the expression of the Hs1 ^pro-1 -mediated nematode resistance were well-maintained in all hairy root cultures even after repeated sub-culture. Received: 25 November 1997 / Revision received: 26 May 1998 / Accepted: 15 June 1998