Functional endogenous LINE-1 retrotransposons are expressed and mobilized in rat chloroleukemia cells.

LINE-1 (L1) is a highly successful autonomous non-LTR retrotransposon and a major force shaping mammalian genomes. Although there are about 600 000 L1 copies covering 23% of the rat genome, full-length rat L1s (L1Rn) with intact open reading frames (ORFs) representing functional master copies for retrotransposition have not been identified yet. In conjunction with studies to elucidate the role of L1 retrotransposons in tumorigenesis, we isolated and characterized 10 different cDNAs from transcribed full-length L1Rn elements in rat chloroleukemia (RCL) cells, each encoding intact ORF1 proteins (ORF1p). We identified the first functional L1Rn retrotransposon from this pool of cDNAs, determined its activity in HeLa cells and in the RCL cell line the cDNAs originated from and demonstrate that it is mobilized in the tumor cell line in which it is expressed. Furthermore, we generated monoclonal antibodies directed against L1Rn ORF1 and ORF2-encoded recombinant proteins, analyzed the expression of L1-encoded proteins and found ORF1p predominantly in the nucleus. Our results support the hypothesis that the reported explosive amplification of genomic L1Rn sequences after their transcriptional activation in RCL cells is based on L1 retrotransposition. Therefore, L1 activity might be one cause for genomic instability observed during the progression of leukemia.

Enhanced constriction of supplying arteries--a mechanism of femoral head necrosis in Wistar rats?

Femoral head necrosis occurs in 8-15% of Wistar Kyoto (WKY) rats, and in up to 46% of spontaneous hypertensive (SHR) rats. For SHR rats, the etiologic factors have been described while the pathomechanism of femoral head necrosis in Wistar rats remains unclear. The aim of this study has been to compare the vasoconstrictive effect of noradrenaline on femoral arteries in common Wistar and SHR rats. Four male SHR rats 180-209 days of age, and four male Wistar rats 179-185 days of age, were used. Seven femoral artery segments were harvested from the SHR rats while 6 artery segments were harvested from the WKY rats. The arterial segments were mounted as ring preparations on a small vessel myograph for isometric force development. The arteries were stimulated cumulatively by adding noradrenaline (0.3-30 microM at 2-min intervals) to obtain the dose-response curve of isometric wall tension. Noradrenaline elicited a concentration-dependent vasocontraction in all arteries. The lumen diameter at standard passive tension L(100) was not different. The dose-response curve showed a stronger constriction of the femoral artery segments in WKY than in SHR rats. The maximal active tension of noradrenaline was 6.4+/-3.4 mN in the WKY, and 3.0+/-1.8 mN (mean+/-S.D), significantly lower, in the SHR group (p<0.05). This study showed that vasoconstriction of the femoral artery in WKY rats was stronger than that of SHR rats. This may be a pathomechanical factor in femoral head necrosis of WKY rats.

Major trauma with multiple injuries in German children: a retrospective review.

BACKGROUND: The aim of this study was to evaluate the demographics, mechanisms, pattern, injury severity, and the outcome (ie, length of intensive care unit [ICU] stay, length of mechanical ventilation, total length of stay, mortality) in multiple-injured children based on a review from the German trauma registry study ("Traumaregister") of the German Society of Trauma Surgery (Deutsche Gesellschaft für Unfallchirurgie e.V.). METHODS: One hundred three German trauma centers took part in the German trauma registry study from January 1997 to December 2003. Five hundred seventeen children (aged 0-15 years) with multiple injuries and an Injury Severity Score of more than 15 in comparison to 11,025 adults were included. Sex, age, and mechanisms and pattern of injury were assessed. The mechanisms of trauma and the anatomical distribution of severe injury (Abbreviated Injury Scale of 3 or more) were analyzed. The Injury Severity Score, the Revised Trauma Score, and the Trauma Score Injury Severity Score were calculated to estimate the severity of injury and mortality. RESULTS: The predominant sex was male. Most cases were caused by traffic-related accidents. Head injuries were most common in children, and severe thoracic injuries increased with age. Mean length of ICU treatment, mechanical ventilation, and total length of stay were shorter in children than in adults. A total of 22.6% of the children aged 0 to 5 years died in the hospital in comparison with in-hospital mortality rate of 13.7% in the 6- to 10-, 20.3% in the 11- to 15-, and 17.0% in the 16- to 55-year-old patients. CONCLUSIONS: There were differences between multiple-injured children and adults concerning injury mechanisms and pattern of injuries. Adults needed a longer mechanical ventilation and a longer ICU therapy. Most deaths could be seen in the youngest patients aged 0 to 5 years.

Cell type-specific expression of LINE-1 open reading frames 1 and 2 in fetal and adult human tissues.

The LINE-1 (L1) family of non-long terminal repeat retrotransposons is a major force shaping mammalian genomes, and its members can alter the genome in many ways. Mutational analyses have shown that coexpression of functional proteins encoded by the two L1-specific open reading frames, ORF1 and ORF2, is an essential prerequisite for the propagation of L1 elements in the genome. However, all efforts to identify ORF2-encoded proteins have failed so far. Here, applying a novel antibody we report the presence of proteins encoded by ORF2 in a subset of cellular components of human male gonads. Immunohistochemical analyses revealed coexpression of ORF1 and ORF2 in prespermatogonia of fetal testis, in germ cells of adult testis, and in distinct somatic cell types, such as Leydig, Sertoli, and vascular endothelial cells. Coexpression of both proteins in male germ cells is necessary for the observed genomic expansion of the number of L1 elements. Peptide mass fingerprinting analysis of a approximately 130-kDa polypeptide isolated from cultured human dermal microvascular endothelial cells led to the identification of ORF2-encoded peptides. An isolated approximately 45-kDa polypeptide was shown to derive from nonfunctional copies of ORF2 coding regions. The presence of both ORF1- and ORF2-encoded proteins in vascular endothelial cells and its apparent association with certain stages of differentiation and maturation of blood vessels may have functional relevance for vasculogenesis and/or angiogenesis.