[A simple biostatistical method for meta analysis of the data on 2 x 2 table]

Meta-analysis is a method in common use for data analysis in evidence-based medicine. In this paper, based on the Mantel-Haenszel and Peto methods used for Meta-analysis of the data on 2 x 2 table, we put forward a simple calculating method for clinicians. It is useful for Meta-analysis and can be easily applied to analysis of the data from multi-studies in evidence-based medicine.

Alcohol consumption, glutathione S-transferase M1 and T1 genetic polymorphisms and breast cancer risk

To evaluate the potential association between GSTM1 and GSTT1 genotypes and development of breast cancer, a hospital based case-control study was conducted in a South Korean study population consisting of 189 histologically confirmed incident breast cancer cases and their 189 age-matched control subjects with no present or previous history of cancer. A multiplex polymerase chain reaction method was used for the genotyping analyses and statistical evaluations were performed by unconditional logistic regression model. The GSTM1 null genotype was significantly associated with breast cancer risk in premenopausal women [odds ratio (OR) = 2.0, 95% confidence interval (CI) = 1-3.7], but not in the postmenopausal women (OR = 0.9, 95% CI = 0.5-1.9), nor in all women grouped together (OR = 1.3, 95% CI = 0.8-1.1). The GSTT1 null genotype posed a similar risk of breast cancer with an OR of 1.6 (95% CI = 1.0-2.5) for the total breast cancer group, OR of 1.7 (95% CI = 0.9-3.2) for pre-menopausal women, and OR of 1.3 (95% CI = 0.6-2.8) for post-menopausal women. The breast cancer risk associated with concurrent lack of both GSTM1 and GSTT1 genes was 2.2 (95% CI = 1.1-4.5), and the risk increased as the number of null genotype increased (P for trend = 0.03). When the data were stratified by the known risk factors of breast cancer, a significant interaction was observed between the GSTM1 genotypes and alcohol consumption (P for interaction = 0.03). An especially remarkable risk of breast cancer was observed for alcohol-consuming premenopausal women lacking both the GSTM1 and GSTT1 genes (OR = 5.3, 95% CI = 1.0-27.8) compared to those with both of the genes. Our findings thus suggest a novel gene-environment interaction which plays an important role in the individual susceptibility to breast cancer. p6

Binding of human mitochondrial transcription factor A, an HMG box protein, to a four-way DNA junction

Mitochondrial transcription factor A (mtTFA), the only known transcription factor in mitochondria, is also implicated in maintenance of mitochondrial genome although little is elucidated about its molecular basis. mtTFA is a member of HMG box proteins family. Some HMG proteins bind with high affinity to four-way DNA junctions that mimic a Holliday structure, a putative intermediate in DNA recombination. To explore possible involvement of a Holliday-like structure in the maintenance of mitochondrial genome, we examine the binding of recombinant human mtTFA to a synthetic four-way DNA junction. The human mtTFA binds to the four-way DNA junction with an approximately 10-fold higher affinity than to the corresponding linear duplex DNA and with essentially the same affinity as to a 40-mer DNA containing the human mitochondrial light strand promoter sequence. The mtTFA binds to the four-way as a monomer. Both of the two HMG box domains of human mtTFA are required for the high affinity binding to the four-way junction.

Accumulation of adenine DNA glycosylase-sensitive sites in human mitochondrial DNA

The mitochondrial respiratory chain inevitably produces reactive oxygen species as byproducts of aerobic ATP synthesis. Mitochondrial DNA (mtDNA), which is located close to the respiratory chain, is reported to contain much more 8-oxoguanine (8-oxoG), an oxidatively modified guanine base, than nuclear DNA. Despite such a high amount of 8-oxoG in mtDNA (1-2 8-oxoG/10(4) G), mtDNA is barely cleaved by an 8-oxoG DNA glycosylase or MutM, which specifically excises 8-oxoG from a C:8-oxoG pair. We find here that about half of human mtDNA molecules are cleaved by another 8-oxoG-recognizing enzyme, an adenine DNA glycosylase or MutY, which excises adenine from an A:8-oxoG pair. The cleavage sites are mapped to adenines. The calculated number of MutY-sensitive sites in mtDNA is approximately 1.4/10(4) G. This value roughly corresponds with the electrochemically measured amount of 8-oxoG in mtDNA (2.2/10(4) G), raising the possibility that 8-oxoG mainly accumulates as an A:8-oxoG pair.

Trichoplusia ni lebocin, an inducible immune gene with a downstream insertion element

A cDNA clone encoding a lebocin-like protein was obtained from the cabbage looper Trichoplusia ni by using differential display PCR. Northern blot analysis showed that lebocin gene expression was inducible upon bacterial challenge. Transcripts were mainly found in fat body but were also observed in hemocytes. Expression reached its highest level at 20 h and continued at least until 60 h after bacterial injection. The deduced protein is proline-rich and contains 143 amino acid residues. At position 128, a possible O-glycosylation site is observed. The whole protein shows 35% identity to Bombyx mori lebocin. The mature peptide displays an N-terminus similar to that of lebocin and a C-terminus to that of Drosophila metchnikowin. A 39-bp repetitive element is located downstream of the coding region.

Polyglutamine expansion down-regulates specific neuronal genes before pathologic changes in SCA1

The expansion of an unstable CAG repeat causes spinocerebellar ataxia type 1 (SCA1) and several other neurodegenerative diseases. How polyglutamine expansions render the resulting proteins toxic to neurons, however, remains elusive. Hypothesizing that long polyglutamine tracts alter gene expression, we found certain neuronal genes involved in signal transduction and calcium homeostasis sequentially downregulated in SCA1 mice. These genes were abundant in Purkinje cells, the primary site of SCA1 pathogenesis; moreover, their downregulation was mediated by expanded ataxin-1 and occurred before detectable pathology. Similar downregulation occurred in SCA1 human tissues. Altered gene expression may be the earliest mediator of polyglutamine toxicity.

The D-loop structure of human mtDNA is destabilized directly by 1-methyl-4-phenylpyridinium ion (MPP+), a parkinsonism-causing toxin

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine has been reported to cause parkinsonism via its neurotoxic form, 1-methyl-4-phenylpyridinium ion (MPP+), which inhibits complex I of the mitochondrial respiratory chain. Its parkinsonism-causing mechanisms attract a great deal of interest as a model of the disease. Recently, we reported that MPP+ strongly decreases the amount of mtDNA independent of the inhibition of complex I. Maintenance of a proper amount of mtDNA is essential for the normal function of mitochondria as exemplified in many mitochondrial diseases. The most characteristic feature in vertebral mtDNA replication is that H-strand synthesis proceeds displacing the parental H-strand as a long single strand. It forms the D-loop, a triplex replication intermediate composed of the parental L-strand, nascent H-strand and displaced H-strand. Here we show that MPP+ does not inhibit DNA synthesis by DNA polymerase gamma, but rather releases the nascent H-strands from mtDNA both in organello and in vitro. This indicates that MPP+ directly destabilizes the D-loop structure, thereby inhibiting replication. This study raises a new mechanism, i.e. destabilization of replication intermediates, for depletion of mtDNA.

FK506 attenuates developing and established joint inflammation and suppresses interleukin 6 and nitric oxide expression in bacterial cell wall induced polyarthritis

OBJECTIVE

To determine the efficacy of therapeutic administration of FK506 (Tacrolimus) in suppressing developing and established joint inflammation, proinflammatory cytokine expression, and nitric oxide (NO) production in peptidoglycan-polysaccharide (PG/PS) induced experimental polyarthritis in rats.

METHODS

Chronic joint inflammation was induced by intraperitoneal injection of PG/PS, and joint inflammation was quantified using arthritis index and paw volume. Serum and joint levels of interleukin 6 (IL-6) were measured by bioassay and Western blot analysis respectively, and serum levels of NO production were determined by the Griess procedure and the expression of the inducible isoform of nitric oxide synthase (i-NOS) in the joints was determined by Western blot analysis.

RESULTS

Arthritis induced by PG/PS is biphasic, progressing through an initial acute phase and a remission phase, which is followed by a persistent chronic phase. Daily administration of FK506 initiated during the remission phase significantly attenuated the onset and development of chronic joint inflammation. We observed a significant reduction in joint inflammation and swelling, an apparent suppression of pannus development, and minimal erosive damage to the articular cartilage and subchondral bone. Fully established chronic joint inflammation was also ameliorated by daily administration of FK506. Joint swelling and inflammation was significantly reduced by 5 days post-treatment with FK506 and the erosive activity associated with the pannus appeared diminished. The elevated expression of IL-6 and NO characteristic of chronic joint inflammation in the serum and in joint tissue was significantly reduced by FK506 treatment.

CONCLUSION

Therapeutic administration of FK506 has a profound antiinflammatory effect on the development of the chronic, erosive arthritis induced by PG/PS. This attenuation in joint inflammation was associated with suppression of IL-6 and NO production systemically and locally in the joints. Our data suggest that FK506 may be effective in the treatment of chronic joint inflammation associated with rheumatoid arthritis.

Molecular phenotype of the human oocyte by PCR-SAGE

Consecutive application of PCR and serial analysis of gene expression (SAGE) was used to generate a catalog of approximately 50, 000 SAGEtags from nine human oocytes. Matches for known genes were identified using the National Institutes of Health SAGEtag database. This database links directly to the UniGene database, providing rapid discrimination between SAGEtags that match known genes and expressed sequence tags and those that currently have no match. Matches in the oocyte SAGE catalog were found for surface receptors, second-messenger systems, and cytoskeletal, apoptotic, and secreted proteins. Many of these proteins were not previously known to be expressed in mammalian oocytes. The relative abundances of transcripts for cytoskeletal proteins and proteins known to be in oocytes are consistent with their documented expression, suggesting an absence of representational distortion by the PCR step. The expression profile of the human oocyte may help identify factors that reprogram somatic cell nuclei to totipotency.

Increased 8-oxo-dGTPase in the mitochondria of substantia nigral neurons in Parkinson's disease

There is growing evidence for the involvement of oxidative stress and mitochondrial respiratory failure in nigral neuronal death in Parkinson's disease (PD). We report increased immunoreactivity of 8-oxo-dGTPase (8-oxo-7, 8-dihydrodeoxyguanosine triphosphatase [hMTH1]), an enzyme known to play an important role in controlling spontaneous mutagenesis, and 8-oxo-7, 8-deoxyguanosine (8-oxo-dG) in the mitochondria of the substantia nigra of 6 PD patients. Our results suggest that hMTH1 might be a useful marker of oxidative stress and can be used to explore the relation between such oxidative stress and genomic instability.

Nucleic acid-binding properties of low-density lipoproteins: LDL as a natural gene vector

The role of apo B-100 as a transcription factor is indicated by the presence of regions in its primary structure that are similar to the DNA-binding domains of the transcription factors ISGF3gamma, STATs, IRFs, and SREBPs as well as by the presence of 11 RNA-binding KH domains. The Apo B-100 sequence also contains numerous bipartite nuclear localization sequences (NLS). A modified gel shift assay was used to show binding of highly purified preparations of human LDLs to fragmented genomic DNA, plasmid DNA, synthetic oligonucleotides (ISRE, 5'-GGGAAACCGAAACTG and E/C, E-box motif and CCAAT, adipocyte-specific genes promoter site), and total RNA from human liver. LDL was observed to bind preferentially to plasmid DNA containing the hCMV IE2 promoter region. In experiments using human liver total RNA, RNA for five different genes was recovered from LDL and VLDL bands. Gene transfection experiments using human skin fibroblast cells were used to study the gene transfer capacity of LDL. Cells transfected with a pEGFP-N1 plasmid DNA and LDL expressed functional GFP, as indicated by fluorescence, at approximately 3 hrs after transfection. Our results strongly support an alternative role for apo B-100, in toto or perhaps as functional fragments, in the control of gene expression and as gene transfer vector.

Pretransitional behavior above the nematic-isotropic phase transition of an auxetic trimer liquid crystal

Static light scattering and electric field-induced Kerr measurements were performed above the nematic-isotropic phase transition of a terminal-lateral-lateral-terminal negative Poisson ratio trimer. For both measurements the inverse susceptibility was observed to be nearly linear with temperature, a result inconsistent with our previously reported Kerr data [Phys. Rev. E 58, 2041 (1998)].

Urinary 1-hydroxypyrene and other PAH metabolites as biomarkers of exposure to environmental PAH in air particulate matter

Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) from occupational, environmental, medicinal and dietary sources. PAH metabolites in human urine can be used as biomarkers of internal dose to assess recent exposure to PAHs. The most widely used urinary PAH metabolites are 1-hydroxypyrene (1-OHP) or 1-hydroxypyrene-O-glucuronide (1-OHP-gluc), the major form of 1-OHP in human urine, because of their relatively high concentration and prevalence in urine and their relative ease of measurement. Elevated levels of 1-OHP or 1-OHP-gluc have been demonstrated in smokers, in patients receiving coal tar treatment (vs. pre-treatment), in postshift road pavers or coke oven workers, and in subjects ingesting charbroiled meat. This metabolite is found (at low levels) in most human urine samples, even in persons without apparent occupational or smoking exposure. Recent studies suggest that environmental exposure to PAHs (and air particles) is associated with increased excretion of 1-OHP-gluc or 1-OHP. These findings raise the possibility of using urinary concentration of 1-OHP-gluc, or another PAH metabolite, as a surrogate biomarker of exposure to airborne fine (sooty) particulate matter--the major source of PAHs in polluted air. Reported associations between ambient particulate matter concentrations and health effects among adults and children, including respiratory disease and mortality, indicate the need for biomarkers of fine particle exposure. If validated, such biomarkers would be useful in supplementing and refining exposure information obtained by ambient monitoring.

Comparison of three analytical methods for 1-hydroxypyrene glucuronide in urine after non-occupational exposure to polycyclic aromatic hydrocarbons

Urinary pyrene metabolites, 1-OHP and 1-OHPG, have been used as biomarkers for the assessment of occupational and environmental exposure to PAHs. This study compares the sensitivity and applicability of the different analytical methods of 1-OHPG for human biomonitoring of low level exposure to PAHs. Three analytical methods were compared: (1) HPLC method from that reported by Singh et al. (Singh, R., Tucek, M., Maxa, K., Tenglerova, J., Weyand, E.H., 1995. A rapid and simple method for the analysis of 1-hydroxypyrene glucuronide: a potential biomarker for polycyclic aromatic hydrocarbon exposure. Carcinogenesis 16, 2909-2915); (2) IAC-SFS method: the rapid and simple assay using IAC purification using monoclonal antibody specific for PAH-DNA adduct and PAH metabolites and SFS quantitation; and (3) IAC-HPLC method: IAC and HPLC separation and quantitation. The correlation between the IAC-SFS method, HPLC method, and the IAC-SFS method was determined in 20 first year-grade junior high school students (age 12-13) from Yochon, Korea who participated in a nationwide survey for the environmental disease surveillance projects in Korea. Chromatograms obtained by the IAC purification and HPLC quantitation method were clear with no interfering peaks adjacent to 1-OHPG, thus 1-OHPG could be easily quantitated. However, the HPLC method produced chromatogram profiles with many interfering peaks adjacent to 1-OHPG peak. The concentrations of 1-OHPG in 20 urine samples were similar when analyzed by all three analytical methods. The correlation coefficient between the IAC-HPLC and IAC-SFS methods was 0.915, and between the IAC-HPLC and HPLC methods was 0.844, and between the IAC-SFS and HPLC methods was 0.805. The analytical methods for 1-OHPG compared in this study showed a good correlation with one another. These results suggest that any of the methods can be applied to human biomonitoring of PAH exposure. However, SFS quantitation after IAC purification is rapid and simple because this method does not need HPLC separation of 1-OHPG.

Variations in urinary 1-hydroxypyrene glucuronide in relation to smoking and the modification effects of GSTM1 and GSTT1

The measurement of the pyrene metabolite, 1-hydroxypyrene, in human urine has been used to assess recent exposure to polycyclic aromatic hydrocarbons (PAH). The objective of this study was to see whether genetic polymorphisms in metabolic enzymes could explain some of the variation in urinary 1-hydroxypyrene glucuronide (1-OHPG) excretion in relation to smoking. Forty-seven male hospital workers, who were not occupationally exposed to PAH, participated in this study. The urine samples were analyzed for 1-OHPG utilizing immunoaffinity chromatography and synchronous fluorescence spectroscopy. The analysis of GSTM1 and GSTT1 polymorphism was performed by PCR. The 1-OHPG concentration in the urine of the hospital workers was 0.57 +/- 0.85 micromol/mol creatinine, and ranged from 0.02 to 5.04 mciromol/mol creatinine. Cigarette smoking was significantly correlated with urinary 1-OHPG (r = 0.3976, P = 0.0056). The 1-OHPG excretion in GSTM1-deficient smokers was higher than that in GSTM1-positive smokers. On the other hand, 1-OHPG excretion was higher in GSTT1-positive smokers than in GSTT1-deficient smokers. It is important to note the variability of individual PAH metabolite excretion due to different GSTM1 and GSTT1 genotypes.

Mitochondrial electron transport complex I is a potential source of oxygen free radicals in the failing myocardium

Oxidative stress in the myocardium may play an important role in the pathogenesis of congestive heart failure (HF). However, the cellular sources and mechanisms for the enhanced generation of reactive oxygen species (ROS) in the failing myocardium remain unknown. The amount of thiobarbituric acid reactive substances increased in the canine HF hearts subjected to rapid ventricular pacing for 4 weeks, and immunohistochemical staining of 4-hydroxy-2-nonenal ROS-induced lipid peroxides was detected in cardiac myocytes but not in interstitial cells of HF animals. The generation of superoxide anion was directly assessed in the submitochondrial fractions by use of electron spin resonance spectroscopy with spin trapping agent, 5, 5'-dimethyl-1-pyrroline-N-oxide, in the presence of NADH and succinate as a substrate for NADH-ubiquinone oxidoreductase (complex I) and succinate-ubiquinone oxidoreductase (complex II), respectively. Superoxide production was increased 2.8-fold (P<0.01) in HF, which was due to the functional block of electron transport at complex I. The enzymatic activity of complex I decreased in HF (274+/-13 versus 136+/-9 nmol. min(-1). mg(-1) protein, P<0.01), which may thus have caused the functional uncoupling of the respiratory chain and the deleterious ROS production in HF mitochondria. The present study provided direct evidence for the involvement of ROS in the mitochondrial origin of HF myocytes, which might be responsible for both contractile dysfunction and structural damage to the myocardium.

Anticlinic coupling between layers of an antiferroelectric liquid crystal

The anticlinic interlayer coupling coefficient U was evaluated as a function of temperature for a pitch-compensated liquid crystal by optical observation of the electric field-induced optic mode. U was found to exhibit an unusual "S-shaped" dependence on temperature, with values ranging between 0.4x10(4) and 2.2x10(4) erg cm(-3) over a 10 degrees C temperature range below the smectic-A-smectic-C(*)(A) phase-transition temperature. The results are in good agreement with estimates for U based upon the threshold field for the onset of solitary waves, and provide strong support in the low-field regime for the single Fourier component model proposed by Li et al. [Phys. Rev. B 52, R13 075 (1995)].

[Health-related quality of life in hypertensive patients]

OBJECTIVES

To explore the health-related quality of life (HRQOL) for hypertensive patients (HBP) and to provide reasonable evidence for evaluating the effectiveness of antihypertensive therapy in clinical practice.

METHODS

A cross-sectional study was used to survey 106 patients with HBP and 127 nomotensives using SF-36 short form of quality of life in the community. The cutoff point score of HRQOL was decided by receiver operating characteristic (ROC) Curve analysis. There were 60 patients with BP > or = 160/95 mm Hg who had been treated by antihypertensive drugs for 6 months. Before and after the treatment, their HRQOL was measured and evaluated, and the relationship between the change of HRQOL and antihypertensive effect was evaluated.

RESULTS

Apart from physical function and pain, other 7 domains were significantly lower in the hypertensive group than in the normotensive group, which included social function, role limitations attributed to both physical and emotional problems, mental health, activity or fatigue and overall evaluation of health (P < 0.05-0.001). A cutoff point of HRQOL was decided using ROC analysis in which the 290 score was the best one for diagnostic HRQOL with the sensitivity of 80% and a specificity of 70%. The target rate of the antihypertensive care and the improved rate of HRQOL for 60 patients with HBP were 63% and 75% separately for a 6-month treatment.

CONCLUSION

The HRQOL of these hypertensives was significantly lower than that in the normotensives in the study. The measurement of HRQOL was more useful to evaluate the antihypertensive effectiveness in clinical practice.

Mitochondrial DNA replication in human T lymphocytes is regulated primarily at the H-strand termination site

The most unique feature in the replication of mitochondrial DNA (mtDNA) is that most of the newly synthesized heavy strands (H-strands) terminate prematurely, resulting in the formation of displacement loop (D-loop) strands. Only the H-strand which proceeds past the termination site is a true nascent H-strand leading to the overall replication on a circular mtDNA molecule. The physiological significance of the D-loop formation has long been unclear. To examine the role of premature termination in mtDNA replication, we therefore developed a method for selectively measuring both the total amount of nascent H-strands and the amount of true nascent H-strands using ligation-mediated polymerase chain reaction, which, for the first time, enabled us to estimate the frequency of premature termination. The stimulation of cell proliferation with interleukin 2 and phytohemagglutinin in human peripheral T lymphocytes caused an increase in the net replication rate of mtDNA. In stimulated cells, in comparison to resting ones, the amount of true nascent H-strands increased approx. 2.6-fold while the total amount of nascent H-strands remained unchanged, indicating that premature termination decreased while the initiation of replication remained the same. Our findings thus demonstrate the first clear example that premature termination plays a primary role in the up-regulation of the net rate of mtDNA replication in human cells.

Evidence for functional conservation of a mammalian homologue of the light-responsive plant protein COP1

Identified in Arabidopsis as a repressor of light-regulated development, the COP1 (constitutively photomorphogenic 1) protein is characterized by a RING-finger motif and a WD40 repeat domain [1]. The subcellular localization of COP1 is light-dependent. COP1 acts within the nucleus to repress photomorphogenic development, but light inactivates COP1 and diminishes its nuclear abundance [2]. Here, we report the identification of a mammalian COP1 homologue that contains all the structural features present in Arabidopsis COP1 (AtCOP1). When expressed in plant cells, a fusion protein comprising mammalian COP1 and beta-glucuronidase (GUS) responded to light by changing its subcellular localization pattern in a manner similar to AtCOP1. Whereas the mammalian COP1 was unable to rescue the defects of Arabidopsis cop1 mutants, expression of the amino-terminal half of mammalian COP1 in Arabidopsis interfered with endogenous COP1 function, resulting in a hyperphotomorphogenic phenotype. Therefore, the regulatory modules in COP1 proteins that are responsible for the signal-dependent subcellular localization are functionally conserved between higher plants and mammals, suggesting that mammalian COP1 may share a common mode of action with its plant counterpart in regulating development and cellular signaling.

The Alzheimer-related gene presenilin 1 facilitates notch 1 in primary mammalian neurons

The normal functional neurobiology of the Alzheimer's disease (AD) related gene presenilin 1 (PS1) is unknown. One clue comes from a genetic screen of Caenorhabditis elegans, which reveals that the presenilin homologue sel-12 facilitates lin-12 function [D. Levitan, I. Greenwald, Facilitation of lin-12-mediated signalling by sel-12, a Caenorhabditis elegans S182 Alzheimer's disease gene, Nature 377 (1995) 351-355]. The mammalian homologue of lin-12, Notch1, is a transmembrane receptor that plays an important role in cell fate decisions during development, including neurogenesis, but does not have a known function in fully differentiated cells. To better understand the potential role of Notch1 in mammalian postmitotic neurons and to test the hypothesis that Notch and PS 1 interact, we studied the effect of Notch1 transfection on neurite outgrowth in primary cultures of hippocampal/cortical neurons. We demonstrate that Notch1 inhibits neurite extension, and thus has a function in postmitotic mature neurons in the mammalian CNS. Furthermore, we present evidence demonstrating that there is a functional interaction between PS1 and Notch1 in mammalian neurons, analogous to the sel-12/lin-12 interaction in vulval development in C. elegans [D. Levitan, T. Doyle, D. Brousseau, M. Lee, G. Thinakaran, H. Slunt, S. Sisodia, I. Greenwald, Assessment of normal and mutant human presenilin function in Caenorhabditis elegans, Proc. Natl. Acad. Sci. U.S.A. 93 (1996) 14940-14944; D. Levitan, I. Greenwald, Effect of Sel-12 presenilin on Lin-12 localization and function in Caenorhabditis elegans, Development, 125 (1998) 3599-3606]. The inhibitory effect of Notch1 on neurite outgrowth is markedly attenuated in neurons from PS1 knockout mice, and enhanced in neurons from transgenic mice overexpressing wild type PS1, but not mutant PS1. These data suggest that PS1 facilitates Notch1 function in mammalian neurons, and support the hypothesis that a functional interaction exists between PS1 and Notch1 in postmitotic mammalian neurons.

Expression and differential intracellular localization of two major forms of human 8-oxoguanine DNA glycosylase encoded by alternatively spliced OGG1 mRNAs

We identified seven alternatively spliced forms of human 8-oxoguanine DNA glycosylase (OGG1) mRNAs, classified into two types based on their last exons (type 1 with exon 7: 1a and 1b; type 2 with exon 8: 2a to 2e). Types 1a and 2a mRNAs are major in human tissues. Seven mRNAs are expected to encode different polypeptides (OGG1-1a to 2e) that share their N terminus with the common mitochondrial targeting signal, and each possesses a unique C terminus. A 36-kDa polypeptide, corresponding to OGG1-1a recognized only by antibodies against the region containing helix-hairpin-helix-PVD motif, was copurified from the nuclear extract with an activity introducing a nick into DNA containing 8-oxoguanine. A 40-kDa polypeptide corresponding to a processed form of OGG1-2a was detected in their mitochondria using antibodies against its C terminus. Electron microscopic immunocytochemistry and subfractionation of the mitochondria revealed that OGG1-2a locates on the inner membrane of mitochondria. Deletion mutant analyses revealed that the unique C terminus of OGG1-2a and its mitochondrial targeting signal are essential for mitochondrial localization and that nuclear localization of OGG1-1a depends on the NLS at its C terminus.

Large-scale optimization of neuron arbors

At the global as well as local scales, some of the geometry of types of neuron arbors-both dendrites and axons-appears to be self-organizing: Their morphogenesis behaves like flowing water, that is, fluid dynamically; waterflow in branching networks in turn acts like a tree composed of cords under tension, that is, vector mechanically. Branch diameters and angles and junction sites conform significantly to this model. The result is that such neuron tree samples globally minimize their total volume-rather than, for example, surface area or branch length. In addition, the arbors perform well at generating the cheapest topology interconnecting their terminals: their large-scale layouts are among the best of all such possible connecting patterns, approaching 5% of optimum. This model also applies comparably to arterial and river networks.

R-Loop in the replication origin of human mitochondrial DNA is resolved by RecG, a Holliday junction-specific helicase

Stable RNA-DNA hybrids (R-loops) prime the initiation of replication in Escherichia coli cells. The R-loops are resolved by Escherichia coli RecG protein, a Holliday junction specific helicase. A stable RNA-DNA hybrid formation in the mitochondrial D-loop region is also implicated in priming the replication of mitochondrial DNA. Consistent with this hypothesis, the 3' ends of the mitochondrial R-loop formed by in vitro transcription are located close to the initiation sites of the mitochondrial DNA replication. This mitochondrial R-loop is resolved by RecG in a dose-dependent manner. Since the resolution by RecG requires ATP, the resolution is dependent on the helicase activity of RecG. A linear RNA-DNA heteroduplex is not resolved by RecG, suggesting that RecG specifically recognizes the higher structure of the mitochondrial R-loop. This is the first example that R-loops of an eukaryotic origin is sensitive to a junction-specific helicase. The resolution of the mitochondrial R-loop by RecG suggests that the replication-priming R-loops have a common structural feature recognized by RecG.

[Estimation of healthy reference intervals for elderly people through the use of outpatient data]

It is important to determine transferable reference intervals as well as uniformity in measured values for inter-regional and inter-institutional availability of clinical test results. For that purpose, the National Committee for Clinical Laboratory Standards (NCCLS) issued forth guidelines in 1995. Some regional institutions in Japan are making efforts to determine normal reference intervals based on these guidelines. We, the Fukuoka Five Hospitals Group, have selected 3,375 healthy reference individuals and have determined the normal reference intervals for the age groups of 20-29, 30-39, 40-49, and 50-59 years old. The rapidly increasing percentage of elderly people gives rise to ever increasing health-care needs for the elderly, which requires normal reference intervals for older age groups. However, we were unable to collect the required number of the reference individuals above 60 years of age. To obtain reference intervals with adequate reliability and usefulness temporally, we made use of the laboratory data of outpatients at Kyushu University Hospital, and were then easily able to collect the required number of elderly individuals. By performing a very simple selection from among the outpatients, our outpatient group became virtually indistinguishable from the group of healthy reference individuals established by us, with regard to many clinical tests, thus enabling us to estimate reference intervals for older age groups. This approach could be adopted in other regions.