Ubiquitous Presence in Mammalian Cells of Enzymatic Activity Specifically Cleaving 8-Hydroxyguanine-containing DNA

Here we report the finding of enzymatic activity that specifically cleaves DNA containing 8-hydroxyguanine (oh⁸Gua) residues in various mammalian cells. To detect this activity, we used a synthetic double-stranded DNA containing a single oh⁸Gua at a defined position as the substrate, and analyzed the products of enzymatic digestion by polyacrylamide gel electrophoresis. Two cleavage sites near the oh⁸Gua residue were detected with partially purified fractions from cow brain and rat liver, and also with preparations from all mammalian tissues examined. These results suggest that enzymatic activity for the removal of oh⁸Gua from DNA is widely distributed in mammalian cells.     

Recent research on the JC virus]

JC virus (JCV) is a causative agent of progressive multifocal leukoencephalopathy and belongs to Polyomavirus. In this article we describe our recent research relating to this virus. First, JCV's major capsid protein VP1 possesses a nuclear localization signal (NLS) and has the ability to construct a virus-like particle (VLP). We have investigated the mechanism of nuclear entry of JCV using VLP, and clarified the role of NLS. In vitro transport assay revealed that wild type VLP (wtVLP), but not deltaNLSVLP, entered the nuclei of cells. The nuclear transport of wtVLP was dependent on the addition of importins alpha and beta and was prevented by antibodies to nuclear pore complex (NPC). These results suggested that JCV VLP binds to cellular importins via the NLS of VP1 and is transported into the nucleus through the NPC. Second, a yeast two-hybrid screen of a human brain cDNA library demonstrated that the fasciculation and elongation protein zeta 1 (FEZ1) and the heterochromatin protein lalpha (HPla) are proteins that interacted with JCV agnoprotein (Agno). In vitro binding assay showed that Agno interacts directly with FEZ1 and HPlalpha. We have also shown that Agno induces the dissociation of FEZ1 from microtubules and dissociates the interaction between HPlalpha and lamin B receptor. We have demonstrated that interaction between Agno and these host proteins inhibited nuclear egress of JCV. Third, in order to inhibit JCV infection in infected cells, we synthesized siRNA which is specific for JCV Agno. Immunoblotting and immunocytochemical analysis demonstrated that expression levels of agnoprotein and VP1 were significantly inhibited by specific siRNA. In addition, levels of viral mRNAs and viral production were decreased in the cells transfected with Agno siRNA. Furthermore, viral production of cell treated with Agno siRNA was significantly inhibited. These results indicate that post-infection treatment with siRNAs, that targets JCV Agno suppresses virus production in JCV infected cells. Thus, siRNA directed against JCV encoding genes may provide a useful tool for suppression of JCV infection.     

The effect of adjuvant therapy with or without tamoxifen on the endocrine function of patients with breast cancer

The ovarian and pituitary functions of 64 operable breast cancer patients undergoing adjuvant therapy with cytotoxic chemotherapy and/or tamoxifen were investigated. The post menopausal patients, divided into 3 treatment groups, one with tamoxifen alone, one with tamoxifen and chemotherapy and the other with chemotherapy alone had serum estradiol 17-β (E2) and progesterone levels lower than the evaluable limits. Although there was no significant difference in the level of estrone sulfate (E1-S) between these three groups, the level of lutainizing hormone (LH) and follicle stimulating hormone (FSH) in the patients treated with tamoxifen alone and tamoxifen and chemotherapy were significantly lower than those treated with chemotherapy alone. The decrease in gonadotropin levels induced by tamoxifen treatment was reversible as it appeared after the initiation of tamoxifen and recovered after its cessation. In the premenopausal patients, a group treated with tamoxifen and chemotherapy had significantly higher E1-S, E2 and progesterone levels and significantly lower gonadotropin levels than a group treated with chemotherapy alone or one treated with a cyclophosphamide regimen. These increases in the levels of estrogen and progesterone were also reversible, and induced by tamoxifen. Thus, adjuvant endocrinochemotherapy causes profound alteration in the hypothalamo-pituitary-ovarian axis and therefore, monitoring a variety of hormonal levels is thought to be necessary for assessing the consequences of adjuvant therapy in breast cancer patients, especially in premenopausal patients using tamoxifen.     

Multiplex PCR assay for rapid identification of oculopathogenic adenoviruses by amplification of the fiber and hexon genes

Eye infections caused by adenovirus (Ad) often result in nosocomial infections and community epidemics with significant rates of morbidity. No antiviral agent effective against Ad is yet available for clinical use. Therefore, early diagnosis is still the mainstay for patient management and the prevention of epidemics. A multiplex PCR assay based on amplification of a combination of the fiber and hexon genes which can identify the six important oculopathogenic serotypes of Ads (Ad serotype 3[Ad3], Ad4, Ad7, Ad8, Ad19, and Ad37) in a single-tube amplification reaction was developed. Ad serotypes could be distinguished by the different amplicon sizes. The assay correctly identified prototype strains as well as isolates in clinical specimens. In comparison with a previously described PCR-restriction fragment polymorphism method, our assay gave unequivocal results for clinical specimens. Our multiplex PCR has the potential to serve as a rapid and cost-effective tool for the typing of important ocular Ads.     

Investigation of initial changes in the mouse olfactory epithelium following a single intravenous injection of vincristine sulphate

To investigate initial changes in the olfactory epithelium, vincristine sulphate (VCR) was administered intravenously once to male BALB/c mice on day 1 in comparison with unilateral bulbectomy (UBT). The light and electron microscopy of the olfactory epithelium, nerve and/or bulb with BrdU-morphometry was performed sequentially. Further, whole-body radioluminography was conducted at 1 and 24 hours postdose. Apoptosis and an increased number of mitotic cells with a tendency toward decreasing BrdU-positive olfactory epithelial cell counts were observed in olfactory epithelial cells at 6 hours postdose of VCR and became more pronounced at 24 hours postdose. These changes disappeared on days 4 or 15, but minimal axonal degeneration was seen in the olfactory nerve from day 4 onward. Semiquantitative measurement of VCR levels in the ethmoturbinals elicited high drug retention even 24 hours after administration. In contrast, UBT showed no effect on mitosis and BrdU-positive cell counts at 6 hours postdose, but severe lesions in the olfactory epithelium and nerve were seen on days 2, 4, and/or 15. The above results suggest that the initial event of VCR-induced apoptosis in the mouse olfactory epithelium would be mitotic arrest with high drug retention, unlike that evoked by UBT.     

Development of enrofloxacin ELISA using a monoclonal antibody tolerating an organic solvent with broad cross-reactivity to other newquinolones

Antibacterial reagents, especially quinolones, are widely used in animals and humans, and have caused serious problems to human health because of their residual contaminants in food. In order to screen for different kinds of newquinolones at the same time, a sensitive and specific enzyme-linked immunoassay (ELISA) has been developed. The anti-enrofloxacin monoclonal antibody was selected because of its ability to react with structurally related newquinolones in organic solvent. The antibody has 100% cross-reactivity with norfloxacin, ciprofloxacin and other newquinolones at 50% inhibition of control values IC₅₀, but not with nitroflazone, sulphadimethoxine. The lowest detection limit of this ELISA was 0.7 ng/ml (ppb) when enrofloxacin was used as the calibrator. Eel extracts were spiked with enrofloxacin and the average recoveries at 10, 50, 100 ng/ml were 98, 102 and 91%, respectively. The proposed ELISA is a useful method for the practical microquantitation of various newquinolones in biological and environmental specimens.     

Establishment of an HIV cell-cell fusion assay by using two genetically modified HeLa cell lines and reporter gene

Infection of human cells with the human immunodeficiency virus type I (HIV-1) can be mimicked by a fusion process between cells expressing the HIV envelope protein (Env) and cells expressing both human CD4 together with the appropriate human chemokine receptors. In this study, a T-tropic HIV cell-cell fusion assay was established that utilized CD4, human CXCR4 and HIV NL4-3 gp160 as fusion components and a T7 polymerase-activated luciferase as a reporter system. The HeLa T4 cells used, expressed CD4 and CXCR4, and the applied HeLa KS386 cells expressed HIV NL4-3 gp160. By combining HeLa T4 cells with HeLa KS386 cells, an approximately about 100- to 300-fold increase in luciferase activity could be elicited relative to the control. The addition of anti-CD4 monoclonal antibody (Mab) (RPA-T4) or anti-CXCR4 Mab (12G5) in the assay significantly inhibited the fusion event; in contrast, an anti-CCR5 Mab (2D7) had no effect, indicating that the fusion assay was CD4 and CXCR4 dependent. In this report, fusion events could be monitored by both the luciferase reporter system and syncytia formation. Fusion events were monitored and compared using these two approaches. The luciferase reporter system was found to be more sensitive than syncytia formation. Moreover, compared with previous HIV fusion models, such as using recombinant vaccinia viruses, this system has several advantages, including simplicity and sensitivity. Finally, the system provides a powerful tool to study fusion mechanisms mediated by T-tropic HIV gp160, as well as to screen for fusion-blocking antibodies and antiviral agents.     

Familial lateral semicircular canal malformation with external and middle ear abnormalities

We report a family with inner ear lateral semicircular canal (LSC) malformation and external and middle ear abnormalities. The family had no history of known syndromes or toxic exposures. Distinct phenotypic manifestations were found in three family members. A young girl exhibited bilateral LSC malformation with a right-sided preauricular tag, a mildly deformed auricle, a stenotic external auditory canal, and a constricted middle ear cavity. She had moderate conductive hearing loss in the right ear but normal hearing in the left ear. Her younger brother exhibited right-sided LSC malformation, microtia, external auditory canal atresia, a malformed middle ear cavity, and abnormal auditory ossicles. He had severe mixed hearing loss in his right ear. Their mother exhibited left-sided LSC malformation without external and middle ear abnormalities, and the hearing was normal in her left ear. None of the three cases had vestibular symptoms, and their results of balance tests were appropriate for the corresponding ages. In contrast, significantly decreased LSC function was revealed by caloric tests in an ear with LSC malformation. Previously, LSC malformation may have been underdiagnosed in patients presenting with external and middle ear abnormalities and their relatives, since this malformation is frequently associated with normal hearing and balance or conductive hearing loss only. To our knowledge, this condition has not been described previously. This condition supports a genetic basis for the combination of LSC malformation and external and middle ear abnormalities and may represent an autosomal dominant condition with variable expressivity.     

Chromosome 1q terminal deletion resulting fromde novo translocation with an acrocentric chromosome

Summary Distal deletion of chromosome 1q has been reported in nearly 30 patients, all being associated with a deletion ranging from the 1q42 or q43 band to 1qter region. Here, we describe a girl with 1q terminal deletion resulting from an unbalancedde novo translocation t(1;D or G)(q44; p11), as revealed by the presence of a satellited feature and an NOR-stained region at the tip of 1q. We suggest that most of the phenotypic abnormalities seen in patients with 1q distal deletion are attributable to the monosomy for band 1q44.