Comparison of DNA-adduct and tissue-available dose levels of MeIQx in human and rodent colon following administration of a very low dose

[2-14C]2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was administered orally (304 ng/kg body-weight dose based upon an average 70-kg-body-weight subject) to 5 human colon-cancer patients (58 to 84 years old), as well as to F344 rats and B6C3F1 mice. Colon tissue was collected from the human subjects at surgery and from the rodents 3.5 to 6 hr after administration. Colon DNA-adduct levels and tissue available doses were measured by accelerator mass spectrometry (AMS). The mean levels of MeIQx in the histologically normal colon tissue were not different among the human (97 +/- 26 pg MeIQx/g), rat (133 +/- 15 pg/g) or mouse (78 +/- 10 pg/g) tissues; and no difference existed between the levels detected in human normal and tumor tissue (101 +/- 15 pg/g). Mean DNA-adduct levels in normal human colon (26 +/- 4 adducts/10(12) nucleotides) were significantly greater (p < 0.01) than in rats (17.1 +/- 1 adduct/10(12) nucleotides) or mice (20.6 +/- 0.9 adduct/10(12) nucleotides). No difference existed in adduct levels between normal and tumor tissue in humans. These results show that MeIQx forms DNA adducts in human colon at low dose, and that the human colon may be more sensitive to the effects of MeIQx than that of mice or rats.     

Eight inhibitory monoclonal antibodies define the role of individual P-450s in human liver microsomal diazepam, 7-ethoxycoumarin, and imipramine metabolism

Serotonergic 5-hydroxytryptamine-1A (5-HT1A) receptors are of interest in the pathophysiology of several neuropsychiatric disorders such as anxiety, depression and schizophrenia. [Carbonyl-11C]WAY-100635 has recently been shown to be suitable for quantitative determination of 5-HT1A receptors in the human brain using PET. For group comparisons of neuroreceptor distribution on a pixel-by-pixel basis, an anatomic standardization technique is required. In the current study, we have built a database of normal 5-HT1A receptor distribution using [carbonyl-11C]WAY-100635 and an anatomic standardization technique. METHOD: A PET examination lasting 63 min was performed on six subjects after intravenous injection of [carbonyl-11C]WAY-100635. The radioactivity of the PET images were integrated in the interval 12-63 min and normalized by the radioactivity of the cerebellum, providing a measure of the binding potential (BP) in each pixel. Each PET image was transformed into a standard brain anatomy using a computerized brain atlas system. From the standardized PET images, the sample mean and the SD of the BP were calculated in each pixel. RESULT: On the anatomically standardized average image, high BP was observed in the cerebral cortices, hippocampus and raphe nucleus, whereas low BP was observed in the basal ganglia and thalamus. This regional distribution is in good agreement with the distribution of 5-HT1A receptors known from in vitro studies. CONCLUSION: The anatomic standardization technique permits building of a database of the normal 5-HT1A receptor distribution in the living human brain. This technique can be applied for group comparisons of neuroreceptor distribution on a pixel-by-pixel basis.     

Pattern of macrophage subpopulations in post-traumatic bone infections after combined operative/antibiotic treatment

Serum samples of 485 uveitis patients were screened for the presence of anti-neutrophil cytoplasmic antibodies using a standardized immunofluorescence test (IIF) on neutrophil granulocytes. Seventeen of these sera contained cytoplasmic (C)-ANCA antibodies, while two of the sera contained perinuclear (P)-ANCA antibodies (both antinuclear antibody (ANA)-positive, one anti-myeloperoxidase (MPO)-positive). None of the C-ANCA-positive sera reacted with proteinase-3 in ELISA using a highly purified proteinase-3 preparation. Four C-ANCA and one P-ANCA-positive serum reacted with MPO. The majority of the sera did react with azurophilic granules in ELISA. The implication of these results is that in patients with uveitis a positive C-ANCA test is not diagnostic for Wegener's granulomatosis, but is most probably caused by the presence of autoantibodies against as yet unknown constituents of azurophilic granules.     

SV40 large T antigen with c-Jun down-regulates myelin P0 gene expression: a mechanism for papovaviral T antigen-mediated demyelination

Expression of myelin proteins has been shown to be altered in transgenic mice that express papovaviral large tumor (T) antigens. This paper analyzes the effect on P0 gene expression in secondary Schwann cells transfected with the SV40 T antigen gene and in Schwann cells immortalized by T antigen. In secondary Schwann cells, both T antigen and c-Jun are required for significant inhibition of the P0 promoter; expression of only one of the proteins is insufficient for repression of the P0 gene. T antigen, c-Jun (p39), and c-Jun-related protein (p47) form an immunoprecipitable complex in SV40 immortalized Schwann cell lines, and T antigen and c-Jun bind independently and as a complex to the P0 promoter. Our data suggest that the probable molecular mechanism underlying the hypomyelination observed in transgenic animals expressing T antigen may be due to the repression of the P0 gene by T antigen and c-Jun.     

Retroviral display of antibody fragments; interdomain spacing strongly influences vector infectivity

Five different single-chain antibody fragments (scFv) against human cell-surface antigens were displayed on murine ecotropic retroviral vectors by fusing them to the Moloney SU envelope glycoprotein. The spacing between the scFv and the SU glycoprotein was varied by fusing the scFv to residue +7 or to residue +1 of Moloney SU and by inserting linker sequences of different lengths between the domains. All of the chimeric envelopes were efficiently incorporated into vector particles and could bind to human cells through their displayed antibody fragments, but did not infect them. The spacing between the scFvs and the SU glycoproteins had no significant effect on the efficiency of envelope expression or viral incorporation and did not affect the binding properties of the chimeric envelopes, nor did it influence the efficiency of targeted gene delivery to human cells by scFv-displaying vectors. However, on murine fibroblasts the infectivity of vectors incorporating the chimeric envelopes was strongly influenced by the length of the interdomain spacer. The titers were very low when the single-chain antibodies were fused through a tripeptide linker to SU residue +7 and were greatly enhanced (up to 10(5)-fold) when they were fused to SU residue +1 through a heptapeptide linker. These results point to the importance of steric interactions between the domains of chimeric envelope glycoproteins and may have implications for retroviral vector design for human gene therapy.