Regional blockade by neuroleptic drugs ofin vivo 3H-spiperone binding in the rat brain. Relation to blockade of apomorphine induced hyperactivity and stereotypies

Summary The regional prevention by neuroleptic drugs of specificin vivo ³H-spiperone binding was studied in the rat brain. L-sulpiride, thioridazine and clozapine were found to reduce the³H-spiperone binding selectively in the olfactory tubercle, septum, substantia nigra region and frontal cortex but not the striatum at dose levels which preferentially block apomorphine (APO) induced hyperactivity. The maximal prevention of specific³H-spiperone binding by l-sulpiride and clozapine reached 60–80% in the former structures while the displacement of striatal³H-spiperone binding did not exceed 40%. In contrast to l-sulpiride, thioridazine and clozapine both chlorpromazine and haloperidol reduced the³H-spiperone binding to the same extent in all regions studied. Chlorpromazine and haloperidol were potent in prevention of striatal³H-spiperone bindingin vivo which reached 60–80% in this structure.     

Mitochondrial repair of 8-oxoguanine is deficient in Cockayne syndrome group B

Reactive oxygen species, which are prevalent in mitochondria, cause oxidative DNA damage including the mutagenic DNA lesion 7,8-dihydroxyguanine (8-oxoG). Oxidative damage to mitochondrial DNA has been implicated as a causative factor in a wide variety of degenerative diseases, and in cancer and aging. 8-oxoG is repaired efficiently in mammalian mitochondrial DNA by enzymes in the base excision repair pathway, including the 8-oxoguanine glycosylase (OGG1), which incizes the lesion in the first step of repair. Cockayne syndrome (CS) is a segmental premature aging syndrome in humans that has two complementation groups, CSA and CSB. Previous studies showed that CSB-deficient cells have reduced capacity to repair 8-oxoG. This study examines the role of the CSB gene in regulating repair of 8-oxoG in mitochondrial DNA in human and mouse cells. 8-oxoG repair was measured in liver cells from CSB deficient mice and in human CS-B cells carrying expression vectors for wild type or mutant forms of the human CSB gene. For the first time we report that CSB stimulates repair of 8-oxoG in mammalian mitochondrial DNA. Furthermore, evidence is presented to support the hypothesis that wild type CSB regulates expression of OGG1.     

Interpreting trends in prostate cancer incidence and mortality in the five Nordic countries

Trends in incidence and mortality rates of prostate cancer were analyzed using data from the national cancer registries of Denmark, Finland, Iceland, Norway, and Sweden. Joinpoint regression models were used to quantify temporal trends for the period from 1980 to 2004. Incidence rates were increasing and similar in the Nordic countries during the 1980s. Around 1990, a more rapid incidence increase began in all Nordic countries except Denmark, where an increase was seen 5 years later. In 2001, incidence rates in Denmark were half of those seen in the other Nordic countries, but mortality rates varied only marginally among countries. Mean annual declines in prostate cancer mortality of 1.9% (95% CI = 0.4% to 3.3%) and 1.8% (95% CI = 0.5% to 3.0%) were observed from 1996 to 2004 in Finland and Norway, respectively. During the same period, mortality rates leveled off in Iceland and Sweden but continued to increase in Denmark. The rapid increase in incidence during the early 1990s coincided with the introduction of the prostate-specific antigen (PSA) test and conveys little information about the occurrence of potentially lethal disease. Mortality rates, however, have recently stabilized or declined in countries where PSA testing and curative treatment have been commonly practiced since the late 1980s. Although other explanatory factors may be in operation, these trends are consistent with a moderate effect of increased curative treatment of early diagnosed prostate cancer and improved treatment of more advanced disease.     

Repair of DNA lesions induced by ultraviolet irradiation and aromatic amines in normal and repair-deficient human lymphoblastoid cell lines

A host cell reactivation (HCR) assay was employed to study thecapacity of a normal and three repair-deficient human lymphoblastoidcell lines to repair DNA damage induced by UV irradiation andthe aromatic amines 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine(PhIP) and N-acetyl-2-aminofluorene (AAF) respectively. Thecell line belonging to xeroderma pigmentosum complementationgroup C (XP-C) removed all three types of damage less efficientlythan the normal cell line, but more efficiently than the cellline belonging to xeroderma pigmentosum complementation groupD (XP-D). The cell line belonging to complementation group Bof Cockayne's syndrome (CS-B) showed reduced host cell reactivation.Fibroblasts from CS-B patients have reduced gene-specific DNArepair, but normal total genomic DNA repair, thus our data suggestthat the HCR assay measures the capacity for gene-specific DNArepair. In the XP-D cell line, which has practically no DNArepair capacity, AAF adducts had a more potent inhibitory effecton gene expression than UV and PhIP adducts. When correctedfor this inhibitory effect, the wild-type, XP-C and CS-B celllines repaired low levels of AAF and UV adducts with similarefficiencies, however, PhIP adducts were repaired less efficiently.     

Positive association between DNA strand breaks in peripheral blood mononuclear cells and polyunsaturated fatty acids in red blood cells from women

Lipid peroxidation of polyunsaturated fatty acids (PUFA) generates reactive products that may cause DNA damage. To examine the possible relationship between DNA damage in peripheral blood mononuclear cells (PBMC) and the concentration of PUFA in red blood cells (RBC), endogenous DNA strand breaks, formamidopyrimidine DNA glycosylase (FPG) sites, and hydrogen peroxide (H2O2) sensitive sites were evaluated by the comet assay in blood samples from 98 Icelandic women. Fatty acid composition of RBC was analyzed by gas chromatography. Endogenous DNA strand breaks in PBMC correlated positively with the concentration of total PUFA, total n-3 PUFA, docosahexaenoic acid, linoleic acid, oleic acid, and palmitic acid in RBC. However, there was no association between FPG sites or H(2)O(2) sensitive sites in DNA in PBMC and the concentration of total PUFA or total saturated fatty acid in RBC. As there was no association between oxidative DNA damage or sensitivity of DNA to oxidative stress and the concentration of PUFA in RBC, the positive association between endogenous DNA strand breaks in PBMC and the concentration of total PUFA in RBC is probably not related to oxidative stress.     

Studies on the role of topoisomerases in general, gene- and strand-specific DNA repair

Using specific inhibitors we have assessed the role of topoisomerasesI and II in DNA repair of the overall genome and in both strandsof an essential gene, the dihydrofolate reductase (DHFR) genein chinese hamster ovary (CHO) cells. In these studies we have:(1) used inhibitors of topoisomerases during the repair incubationand (2) studied the DNA repair in cells with altered levelsof topoisomerase activity. When cells were allowed to repairafter UV irradiation, the gene-specific DNA repair was not affectedby either topoisomerase I or topoisomerase II inhibitors alone.However, when topoisomerase I and topoisomerase II inhibitorswere added simultaneously the gene- and strand-specific DNArepair were markedly inhibited. In contrast, the overall genomeDNA repair was only marginally affected. This suggests thattopoisomerases are involved in gene-specific DNA repair andthat one type may substitute for the other in the repair process.That concept is further supported by our findings using a mutantcell line with a decreased level of topoisomerase I: gene-specificDNA repair can be inhibited by a topoisomerase II inhibitoralone. By analyzing the steady-state expression of the DHFRgene we find that inhibition of repair in the DHFR gene is notascribed to an obvious change in the messenger level. Furthermore,using agents other than UV, we observe that the inhibitors haveno effect on gene-specific repair of DNA damage introduced bythe chemotherapeutic agents cisplatin and nitrogen mustard.     

Acute isovolemic hemodilution triggers proinflammatory and procoagulatory endothelial activation in vital organs: role of erythrocyte aggregation

OBJECTIVES: The essential role of erythrocytes as oxygen carriers is historically well established, but their function to aggregate and the consequences on the microcirculation is under debate. The pathogenic potential of low erythrocyte aggregation could be important for patients undergoing on-pump cardipopulmonary bypass. These patients are severely hemodiluted due to preoperative isovolemic hemodilution (IHD), circuit priming, and large fluid infusions perioperatively. Considering the vascular endothelium sensitivity to variations in blood rheology, the authors hypothesize that low erythrocyte aggregation will be responsible for activation of vascular endothelium during acute IHD. METHODS: Acute IHD (30 mL/kg exchange transfusion with colloid solutions) was induced in an "aggregating species"(pigs, n = 15). The hypoxic oxidative stress (plasma malondialdehyde, ex vivo oxygen radicals production in heart, lung, kidney, liver, and ileum tissue biopsies), erythrocyte aggregation (LORCA), and endothelial activation (real-time quantitative RT-PCR on von Willebrand factor (vWF), E- and P-selectins, endothelial nitric oxide synthase gene-expression in tissue biopsies) were investigated. RESULTS: The production of superoxide and hydroxyl radicals, measured as H2O2 generation, was similar at all times in sham-operated and hemodiluted animals, proving a maintained oxygen delivery to tissues. Acute IHD was followed by a dramatic drop in erythrocyte aggregation and immediate prothrombotic (significant vWF mRNA upregulation in heart, lungs, kidney, liver, ileum) and proinflammatory (significant E- and P-selectins mRNA upregulation in lungs and ileum) endothelial activation. Low erythrocyte aggregation was significantly correlated with increased mRNA-expression of vWF (heart, liver, ileum) and P-selectin (lungs, ileum, and heart). CONCLUSIONS: These results suggest that low erythrocyte aggregation might trigger endothelium-dependent thrombogenic and proinflammatory response during acute isovolemic hemodilution.     

Testicular germ cell tumours in Iceland: a nationwide clinicopathological study

The purpose of this study was to examine the pathology of all germ cell tumours of the testis diagnosed in Iceland 1955-2002. A total of 214 patients were included in the study. The current age-standardized incidence was found to be 6.1 per 100,000 and had increased almost fourfold during the study period. Seminoma was diagnosed in 55% of cases. Non-seminomas were diagnosed in 45%, and these were further classified as mixed germ cell tumours (33%), embryonal carcinoma (8%), teratoma (3%), and yolk sac tumour (n=1). The mean age at diagnosis was significantly higher for the seminomas than the non-seminomas (38 years versus 29 years) (p<0.001) and the non-seminomas were diagnosed at a significantly higher stage than the seminomas (p<0.001). Thus, in seminoma patients the tumour was localized to the testis (stage I) in 81% of cases, in 17% of patients the tumour had spread to the lymph nodes (stage II or III), and only 2% had extranodal metastasis at diagnosis (stage IV). In contrast, in the non-seminoma patients, the tumours were found to be stage I in 56%, stage II or III in 24%, and stage IV in 20% of cases. No significant difference in staging was found between non-seminoma subtypes. Identification of necrosis or vascular invasion was significantly associated with metastatic disease at diagnosis (p=0.002). During the study period a significant increase in stage I tumours was found as well as a decrease in the size of the tumours.