Tunable Magnetism in Atomically Thin Itinerant Antiferromagnet with Room-Temperature Ferromagnetic Order

Addressing the need for modulated spin configurations is crucial, as they serve as the foundational building blocks for next-generation spintronics, particularly in atomically thin structures and at room temperature. In this work, we realize intrinsic ferromagnetism in monolayer flakes and tunable ferro-/antiferromagnetism in (Fe0.56Co0.44)5GeTe2 antiferromagnets. Remarkably, the ferromagnetic ordering (≥1 L) and antiferromagnetic ordering (≥4 L) remain discernible up to room temperature. The TC (∼310 K) of the monolayer flakes sets a record high for known exfoliated monolayer van der Waals magnets. Within the framework of A-type antiferromagnetism, a notable odd-even layer-number effect at elevated temperatures (T = 150 K) is observed. Of particular interest is the strong ferromagnetic order in even-layer flakes at low temperatures. The intricate interplay among magnetic field strength, layer number, and temperature gives rise to a diverse array of phenomena, holding promise not only for new physics but also for practical applications.

Anomalous electrons in a metallic kagome ferromagnet

Ordinary metals contain electron liquids within well-defined 'Fermi' surfaces at which the electrons behave as if they were non-interacting. In the absence of transitions to entirely new phases such as insulators or superconductors, interactions between electrons induce scattering that is quadratic in the deviation of the binding energy from the Fermi level. A long-standing puzzle is that certain materials do not fit this 'Fermi liquid' description. A common feature is strong interactions between electrons relative to their kinetic energies. One route to this regime is special lattices to reduce the electron kinetic energies. Twisted bilayer graphene1-4 is an example, and trihexagonal tiling lattices (triangular 'kagome'), with all corner sites removed on a 2 × 2 superlattice, can also host narrow electron bands5 for which interaction effects would be enhanced. Here we describe spectroscopy revealing non-Fermi-liquid behaviour for the ferromagnetic kagome metal Fe3Sn2 (ref. 6). We discover three C3-symmetric electron pockets at the Brillouin zone centre, two of which are expected from density functional theory. The third and most sharply defined band emerges at low temperatures and binding energies by means of fractionalization of one of the other two, most likely on the account of enhanced electron-electron interactions owing to a flat band predicted to lie just above the Fermi level. Our discovery opens the topic of how such many-body physics involving flat bands7,8 could differ depending on whether they arise from lattice geometry or from strongly localized atomic orbitals9,10.

Charge fluctuations in the intermediate-valence ground state of SmCoIn5

The microscopic mechanism of heavy band formation, relevant for unconventional superconductivity in CeCoIn5 and other Ce-based heavy fermion materials, depends strongly on the efficiency with which f electrons are delocalized from the rare earth sites and participate in a Kondo lattice. Replacing Ce3+ (4f1, J = 5/2) with Sm3+ (4f5, J = 5/2), we show that a combination of the crystal electric field and on-site Coulomb repulsion causes SmCoIn5 to exhibit a Γ7 ground state similar to CeCoIn5 with multiple f electrons. We show that with this single-ion ground state, SmCoIn5 exhibits a temperature-induced valence crossover consistent with a Kondo scenario, leading to increased delocalization of f holes below a temperature scale set by the crystal field, Tv ≈ 60 K. Our result provides evidence that in the case of many f electrons, the crystal field remains the dominant tuning knob in controlling the efficiency of delocalization near a heavy fermion quantum critical point, and additionally clarifies that charge fluctuations play a general role in the ground state of "115" materials.

Two-dimensional characterization of three-dimensional magnetic bubbles in Fe3Sn2 nanostructures

We report differential phase contrast scanning transmission electron microscopy (TEM) of nanoscale magnetic objects in Kagome ferromagnet Fe3Sn2 nanostructures. This technique can directly detect the deflection angle of a focused electron beam, thus allowing clear identification of the real magnetic structures of two magnetic objects including three-ring and complex arch-shaped vortices in Fe3Sn2 by Lorentz-TEM imaging. Numerical calculations based on real material-specific parameters well reproduced the experimental results, showing that the magnetic objects can be attributed to integral magnetizations of two types of complex three-dimensional (3D) magnetic bubbles with depth-modulated spin twisting. Magnetic configurations obtained using the high-resolution TEM are generally considered as two-dimensional (2D) magnetic objects previously. Our results imply the importance of the integral magnetizations of underestimated 3D magnetic structures in 2D TEM magnetic characterizations.

Target Bubbles in Fe3Sn2 Nanodisks at Zero Magnetic Field

We report a vortex-like magnetic configuration in uniaxial ferromagnet Fe₃Sn₂ nanodisks using differential phase contrast scanning transmission electron microscopy. This magnetic configuration is transferred from a conventional magnetic vortex using a zero-magnetic-field warming process and is characterized by a series of concentric cylinder domains. We termed them as "target bubbles" that are identified as three-dimensional depth-modulated magnetic objects in combination with numerical simulations. Target bubbles have room-temperature stability even at zero magnetic field and multiple stable magnetic configurations. These advantages render the target bubble an ideal bit to be an information carrier and can advance magnetic target bubbles toward functionalities in the long term by incorporating emergent degrees of freedom and purely electrically controllable magnetism.

319. RELAXIN REGULATES AQUAPORIN EXPRESSION IN THE CERVIX OF LATE PREGNANT MICE

Aquaporins (AQPs) have been implicated in the regulation of fluid balance in the cervix during pregnancy to promote hydration, a characteristic of cervical ripening in late gestation.There are four AQPs in the cervix; AQP3, 4, 5 and 8. Cervical fluid balance involves AQP5 and 8 in early pregnancy and AQP3 and 4 in late pregnancy [1]. However, the factors involved in the regulation of cervical AQPs are unknown. We propose that the ovarian peptide hormone relaxin regulates cervical AQPs because high circulating levels of relaxin correspond to changes in AQPs and it is involved in cervical ripening. To test this hypothesis, expression of aqp3, 5 and 8 was compared in the cervices of relaxin wildtype (Rln+/+) and relaxin knockout (Rln–/–) at various stages of pregnancy (day 14.5, 16.5 and 18.5 pregnancy) by quantitative PCR. In the Rln–/– mice, aqp3 expression was significantly lower on day 18.5 gestation compared to Rln+/+ littermates. Aqp5 and 8 expression did not change significantly between genotypes. To determine whether relaxin could restore the Rln+/+ phenotype, Rln–/– mice were implanted with Alzet osmotic minipumps on day 12.5 pregnancy to infuse either recombinant H2 human relaxin (200 μg/mL; Corthera Inc) or 0.9% saline as a control. Cervices were collected after 4 or 6 days of infusion for gene expression analysis. Relaxin infusion in pregnant Rln–/– mice increased cervical aqp3, and also decreased aqp5 expression compared with saline-controls in the 6-day infusion group. Additionally, relaxin treatment caused a 6-fold increase in cervix wet weight, dispersal of collagen fibres and a decrease in relaxin receptor (Rxfp1) expression. These data suggest that relaxin promotes cervical hydration through an action on AQPs. (1) Anderson et al, 2006. Endocrinology 147(1): 130–140.

Rapid degradation of hypoxia-inducible factor-1alpha by KRH102053, a new activator of prolyl hydroxylase 2

BACKGROUND AND PURPOSE

Hypoxia-inducible factor (HIF) is a transcription factor induced by hypoxia and degraded by ubiquitin-dependent proteasomes in normoxic conditions. Under hypoxic conditions, hydroxylation of HIF-1alpha subunit by prolyl hydroxylase (PHD) is suppressed, thus leading to increased levels of HIF. Although PHD2 plays a key role in regulating the levels of HIF, chemical activators of PHD2 are relatively unknown. The aim of this study was to identify small molecule activators of PHD2 that could be used, eventually, to suppress the level of HIF-1alpha.

EXPERIMENTAL APPROACH

By using the overproduced PHD2 as a target, a molecular library consisting of more than 600 small molecules with a benzopyran structure was screened with an HPLC assay method.

KEY RESULTS

We found a potent activator of PHD2, KRH102053 (2-amino-4-methylsulphanyl-butylic acid-4-methoxy-6-(4-methoxy-benzylamino)-2,2-dimethyl-chroman-3-yl ester). The effects of KRH102053 on controlling HIF were studied in human HOS osteosarcoma, rat PC12 phaeochromocytoma and human HepG2 hepatoma cells. Under our experimental conditions, KRH102053 decreased the protein level of HIF-1alpha and the mRNA levels of HIF-regulated downstream target genes, such as vascular endothelial growth factor, aldolase A, enolase 1 and monocarboxylate transporter 4. Consistent with these results, KRH102053 also inhibited the rates of HIF-related migration and invasion of HOS cells as well as the degree of tube formation in human umbilical vein endothelium cells.

CONCLUSIONS AND IMPLICATIONS

These results suggest that KRH102053 and its structural analogues have the potential for use as therapeutic agents against various diseases associated with HIF.

Nuclear localisation of glutathione S-transferase pi is an evaluation factor for drug resistance in gynaecological cancers

AIMS

Nuclear glutathione S-transferase pi (GST7pi) has been reported to protect cancer cells against anticancer drugs. The aim of the present study was to evaluate the clinical significance of nuclear GSTpi in gynaecological cancer.

MATERIALS AND METHODS

We carried out an immunohistochemical analysis of GSTpi, and examined the correlation between nuclear GSTpi: expression and prognosis in 43 epithelial ovarian cancers. We compared expression levels before and after chemotherapy in uterine cervical cancers and endometrial cancers.

RESULTS

The 5-year progression-free survival rate of the nuclear GSTpi-positive group was lower than that of the cytoplasmic GSTpi-positive group, and was significantly lower than that of the negative group (14.3% vs 34.8% vs 66.7%; P = 0.041). The expression of nuclear GSTpi was compared before and after chemotherapy in uterine cervical and endometrial cancers. In eight out of 12 cases (66.7%), the expression turned positive after the chemotherapy.

CONCLUSIONS

We suggest that nuclear localisation of GSTpi is associated with drug resistance. The nuclear localisation of GSTpi in tumour cells is a useful prognosticator, and may contribute to the selection of anticancer drugs for gynaecological cancers.

Differential cell death induced by salsolinol with and without copper: possible role of reactive oxygen species

Salsolinol (SAL), a novel dopaminergic catechol tetrahydroisoquinoline neurotoxin, has been speculated to contribute to the etiology of Parkinson's disease and neuropathology of chronic alcoholism. Our previous studies have demonstrated that SAL induces strand scission in øX174 supercoiled DNA and oxidative base modification in calf thymus DNA in the presence of cupric ion. We now report that treatment of rat pheochromocytoma (PC12) cells with SAL causes reduced viability, which was exacerbated by Cu(2+). The copper chelator bathocuproinedisulfonic acid ameliorated cytotoxicity induced by SAL and Cu(2+). N-Acetyl-L-cysteine and reduced glutathione protected against SAL- plus Cu(2+)-mediated PC12 cell death. Cells exposed to SAL underwent apoptosis, as revealed by characteristic morphological and biochemical changes. SAL treatment resulted in increased levels of Bax with a concomitant decrease in expression of Bcl-x(L). Furthermore, SAL rapidly activated c-Jun N-terminal kinase, whereas the activity of extracellular signal-regulated protein kinase remained unchanged. Transfection with Bcl-x(L) or Bcl-2 led to protection against SAL-mediated PC12 cell death. Although SAL alone could cause apoptotic death in PC12 cells, cells treated with SAL together with Cu(2+) became necrotic. Cells exposed to both SAL and Cu(2+) exhibited higher levels of intracellular reactive oxygen species, malondialdehyde, and 8-oxo-7,8-dihydro-2'-deoxyguanosine than did those treated with SAL alone. These results suggest that copper accelerates redox cycling of SAL, leading to massive production of reactive oxygen species, which can divert the SAL-induced cell death to necrosis.

Neuroprotective and neurotrophic effects of quinic acids from Aster scaber in PC12 cells

Aster scaber T. (Asteraceae) has been used to treat bruises, snakebite, headache, and dizziness in traditional Chinese medicine. In the present study, the neuroprotective effect of four quinic acid derivatives from A. scaber on amyloid Abeta-induced PC12 cell toxicity was investigated. When cells were treated with quinic acid derivatives prior to Abeta, cell toxicity was significantly diminished. Among quinic acid derivatives, (-)4,5-dicaffeoyl quinic acid (1) gave the highest protection against Abeta-induced cell toxicity. In addition, the neurotrophic effects of compounds were evaluated by microscopically monitoring their potency to induce neurite outgrowth in PC12 cells. Four quinic acid derivatives from A. scaber promoted neurite outgrowth in PC12 cells. Interestingly, a novel quinic acid, (-)3,5-dicaffeoyl-muco-quinic acid (2) was more effective than the other compounds in promoting neurite outgrowth. Unlike nerve growth factor, the withdrawal of quinic acids did not result in any significant decrease in cell viability. The results suggest that quinic acid derivatives from A. scaber might potentially be used as a therapeutic agent in Alzheimer disease.

Apoptosis of PC12 cells by 4-hydroxy-2-nonenal is mediated through selective activation of the c-Jun N-terminal protein kinase pathway

Cytotoxic lipid peroxides such as 4-hydroxy-2-nonenal (HNE) are produced when cells are exposed to toxic chemicals. However, the mechanism by which HNE induces cell death has been poorly understood. In this study, we investigated the molecular mechanism of HNE-induced apoptosis in PC12 cells by measuring the activities of the mitogen-activated protein (MAP) kinases involved in early signal transduction pathways. Within 15-30 min after HNE treatment, c-Jun N-terminal protein kinase (JNK) was maximally activated, before returning to control level after 1 h post-treatment. In contrast, activities of extracellular signal regulated kinase (ERK) and p38 MAP kinase remained unchanged from their basal levels. SEK1, an upstream kinase of JNK, was also activated (phosphorylated) within 5 min after HNE treatment and remained activated for up to 60 min. Marked activation of the JNK pathway through SEK1 was demonstrated by the transient transfection of cDNA for wild type SEK1 and JNK into COS-7 cells. Furthermore, significant reductions in JNK activation and HNE-induced cell death were observed when the dominant negative mutant of SEK1 was co-transfected with JNK. Pretreatment of PC12 cells with a survival promoting agent, 8-(4-chlorophenylthio)-cAMP, prevented both the HNE-induced JNK activation and apoptosis. Nonaldehyde, a nontoxic aldehyde, caused neither apoptosis nor JNK activation. Pretreatment of PC12 cells with SB203580, a specific inhibitor of p38 MAP kinase, had no effect on HNE-induced apoptosis. All these data suggest that the HNE-mediated apoptosis of PC12 cells is likely to be mediated through the selective activation of the SEK1-JNK pathway without activation of ERK or p38 MAP kinase.

Cytochrome P450 2E1 (CYP2E1)-dependent production of a 37-kDa acetaldehyde-protein adduct in the rat liver

Ethanol-inducible cytochrome P450 2E1 (CYP2E1) has been shown to be involved in the metabolism of both ethanol and acetaldehyde. Acetaldehyde, produced from ethanol metabolism, is highly reactive and can form various protein adducts. In this study, we investigated the role of CYP2E1 in the production of a 37-kDa acetaldehyde-protein adduct. Rats were pairfed an isocaloric control or an alcohol liquid diet with and without cotreatment of YH439, an inhibitor of CYP2E1 gene transcription, for 4 weeks. The soluble proteins from rat livers of each group were separated on SDS-polyacrylamide gels followed by immunoblot analysis using specific antibodies against the 37-kDa protein acetaldehyde adduct. In addition, catalytic activities of the enzymes involved in alcohol and acetaldehyde metabolism were measured and compared with the adduct level. Immunoblot analysis revealed that the 37-kDa adduct, absent in the pair-fed control, was evident in alcohol-fed rats but markedly reduced by YH439 treatment. Immunohistochemical analysis also showed that the 37-kDa adduct is predominantly localized in the pericentral region of the liver where CYP2E1 protein is mainly expressed. This staining disappeared in the pericentral region after YH439 treatment. The levels of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase isozymes were unchanged after YH439 treatment. However, the level of the 37-kDa protein adduct positively correlated with the hepatic content of P4502E1. These data indicate that the 37-kDa adduct could be produced by CYP2E1-mediated ethanol metabolism in addition to the ADH-dependent formation.

Selective activation of the c-Jun N-terminal protein kinase pathway during 4-hydroxynonenal-induced apoptosis of PC12 cells

The by-product of lipid peroxidation, 4-hydroxynonenal (HNE), was shown to cause apoptosis in PC12 cells. In this study, we investigated the molecular mechanism of HNE-induced apoptosis in these cells. Specifically, we determined the effect of HNE on the activities of mitogen-activated protein (MAP) kinases involved in early signal transduction. Within 15 to 30 min after HNE treatment, c-Jun N-terminal protein kinase (JNK) was maximally activated, before it returned to control level at 1 h post-treatment. In contrast, activities of extracellular signal-regulated kinase and p38 MAP kinase remained unchanged from their baseline levels. Stress-activated protein kinase kinase (SEK1), an upstream kinase of JNK, was also activated within 5 min after HNE treatment and remained activated for up to 60 min. Marked activation of the JNK pathway through SEK1 and apoptosis signal-regulating kinase 1 (ASK1), an upstream kinase of SEK1, was demonstrated by the transient transfection of cDNA for wild-type SEK1 or ASK1 together with JNK into COS-7 cells. Furthermore, significant reductions in JNK activation and HNE-induced cell death were observed when either of the dominant negative mutant of SEK1 or ASK1 was cotransfected with JNK. Pretreatment of PC12 cells with a survival-promoting agent, 8-(4-chlorophenylthio)-cAMP, prevented both the HNE-induced JNK activation and apoptosis. Nonaldehyde, a nontoxic aldehyde, neither caused apoptosis nor JNK activation. Pretreatment of PC12 cells with SB203580, a specific inhibitor of p38 MAP kinase, had no effect on HNE-induced apoptosis. All these data suggest that the selective JNK activation by HNE is critical for the apoptosis of PC12 cells and that the HNE-mediated apoptosis is likely to be mediated through the activation of the ASK1-SEK1-JNK pathway without activation of extracellular signal-regulated kinase or p38 MAP kinase.

Purification and characterization of a novel protamine kinase in HL60 cells

A protamine kinase from HL60 cells was purified to near homogeneity by DEAE-Sephacel, protamine-agarose, Hydroxylapatite, and S-200 chromatography. It was purified by 75.8-fold through four chromatographic steps, and 0.67% of total activity was recovered. The purified enzyme had an apparent molecular mass of 120 kDa and was activated by Mg(2+) or Mn(2+), but inhibited by Ca(2+). Neither phospholipid nor phorbol ester significantly affected the enzyme activity. Staurosporine was the most potent inhibitor of the enzyme among the protein kinase inhibitors tested, K(252a), H(7), heparin, and staurosporine. The purified protamine kinase exhibited a maximum velocity of 5,000 pmol/min/mg and K(m) of 1.3 mM for protamine sulfate as a substrate. Myelin basic protein and protamine sulfate served as the best substrates for the protamine kinase among those tested. The activity of the protamine kinase remained unchanged upon treatment with PMA, retinoic acid, dimethyl sulfoxide, or 1,25 dihydroxy vitamin D(3) for 15 min, while treatment with a differentiating agent, 1,25 dihydroxy vitamin D(3), for one week increased its activity. These results suggest that protamine kinase in HL60 cells is involved in the late stage of the macrophage-monocytic differentiation pathway and may play a role in maintenance of the differentiation after HL60 cells are committed.

Use of 99mTc-mercaptoacetyltriglycine (MAG3)-biocytin hepatobiliary scintigraphy to study the protective effect of a synthetic enzyme inhibitor on acute hepatotoxicity in mice

Recent data suggest that inhibitors of ethanol-inducible cytochrome P450 (CYP2E1) can protect the liver from injury caused by various substrates of CYP2E1. In this study, we measured the protective effect of isopropyl-2-(1,3-dithioetane-2-ylidene)-2[N-(4-methylthiazol -2-yl)-carbamoyl]acetate (YH439), a transcriptional inhibitor of CYP2E1, against carbon tetrachloride (CCl4)-induced hepatotoxicity by using various conventional methods and dynamic scintigraphy with 99mTc-mercaptoacetyltriglycine (MAG3)-biocytin, a recently developed scintigraphic agent. Balb/c mice were pretreated with two doses of YH439 (50 or 150 mg/kg per day) at 48 h and 24 h and one dose of CCl4 (0.25 mL/kg) at 18 h before scintigraphy. The results were compared with those of two other groups, one that received CCl4 but not YH439, and the other that received neither (control). Scintigraphic images were acquired continuously at 15-sec intervals for 30 min. Pharmacokinetic parameters, such as peak liver/heart ratio (r(max)), peak liver uptake time (t(max)), and hepatic half-clearance time (HCT), were obtained from time-activity curves derived from regions-of-interest (ROI) over the liver and the heart. Acute administration of CCl4 alone caused centrilobular necrosis and serum transaminase levels to rise more than 5 times higher than those of the control group. Pharmacokinetic parameters also changed significantly from those of the control group. Administration of YH439 prevented centrilobular necrosis and significantly improved pharmacokinetic parameters. This study demonstrates for the first time that hepatobiliary scintigraphy can be used to study in vivo biochemistry of the CYP2E1 inhibitor (YH439) against liver toxicity.

Critical role of arg433 in rat transketolase activity as probed by site-directed mutagenesis

It has been shown that one arginine per monomer at an unknown position is essential for enzyme activity of the homodimeric transketolase (TK) [Kremer, Egan and Sable (1980) J. Biol. Chem. 255, 2405-2410]. To identify the critical arginine, four highly conserved arginine residues of rat TK (Arg102, Arg350, Arg433 and Arg506) were replaced with alanine by site-directed mutagenesis. Wild-type and mutant TK proteins were produced in Escherichia coli and characterized. The Arg102-->Ala mutant exhibited similar catalytic activity to the wild-type enzyme, whereas Arg350-->Ala, Arg506-->Ala and Arg433-->Ala mutants exhibited 36.7, 37.0 and 6.1% of the wild-type activity respectively. Three recombinant proteins (wild-type, Arg350-->Ala and Arg433-->Ala) were purified to apparent homogeneity using Ni2+-affinity chromatography and further characterized. All these proteins were able to form homodimers (148 kDa), as shown by immunoblot analysis subsequent to non-denaturing gel electrophoresis. The Arg433-->Ala mutant protein was less stable than the wild-type and Arg350-->Ala proteins at 55 degrees C. Kinetic analyses revealed that both Vmax and Km values were markedly affected in the Arg433-->Ala mutant. The Km values for two substrates xylulose 5-phosphate and ribose 5-phosphate were 11.5- and 24.3-fold higher respectively. The kcat/Km values of the Arg433-->Ala mutant for the two substrates were less than 1% of those of the wild-type protein. Molecular modelling of the rat TK revealed that Arg433 of one monomer has three potential hydrogen-bond interactions with the catalytically important highly conserved loop of the other monomer. Thus, our biochemical analyses and modelling data suggest the critical role of the previously uncharacterized Arg433 in TK activity.

Molecular characterization of fetal alcohol syndrome using mRNA differential display

The molecular pathogenesis of fetal alcohol syndrome (FAS) has not been well elucidated. The technique of mRNA differential display was used to characterize the etiology and to identify potential markers for FAS. Out of approximately 1,080 mRNA transcripts in mouse embryos that were analyzed, the levels of three mRNAs were altered by ethanol. Two of these mRNAs (one novel and one encoding heat shock protein 47) were also modulated by another teratogen, 3-methylcholanthrene. The third mRNA, encoding alpha-tropomyosin, was specifically up-regulated by ethanol. Consistent with the Northern blot data, immunoblot analysis demonstrated that the level of alpha-tropomyosin protein (31 kDa, most likely a brain specific isoform) was elevated in the embryos exposed to ethanol.

Immunological detection of CYP2E1 in fresh rat lymphocytes and its pretranslational induction by fasting

The level of ethanol-inducible cytochrome P450 2E1 (CYP2E1) in fresh lymphocytes compared with cultured cells and its induction mechanism by fasting were studied. CYP2E1 in the homogenate and S-9 fraction of fresh lymphocytes was elevated about 5-fold by fasting, comparable to the induction observed in cultured lymphocytes. This induction was accompanied by increased level of CYP2E1 mRNA, confirmed by nested RT-PCRs, Southern blot, and DNA sequence analysis. Our data thus demonstrated that CYP2E1 in fresh lymphocytes is pretranslationally induced by fasting, in parallel to the hepatic enzyme, and that measurement of CYP2E1 in the lymphocyte homogenate can be useful to estimate the hepatic CYP2E1 level in a relatively noninvasive manner.

Transcriptional inhibition of cytochrome P4502E1 by a synthetic compound, YH439

The molecular mechanism of cytochrome P4502E1 (CYP2E1) inhibition by a synthetic compound, YH439, was studied. In rats treated with YH439, N-nitrosodimethylamine demethylase activity and the amount of immunoreactive CYP2E1 were rapidly decreased in time- and dose-dependent manners. Within 2 h after a single dose of YH439 (150 mg/kg), the CYP2E1-catalyzed activity in uninduced rats was decreased by about 30% and by 43% at 24 h after YH439 injection. YH439 treatment also reduced the elevation of CYP2E1 enzyme activity in starved (induced) animals by 34%. More profound inhibition of CYP2E1 protein levels was observed by immunoblot analysis. The level of CYP2E1 catalytic activity and immunoreactive protein remained suppressed for at least 48 h and returned to normal level at 72 h after YH439 treatment. The levels of immunoreactive CYP2B1/2 protein and catalytic activity were moderately increased while little change was observed in the levels of NADPH-dependent P450 oxidoreductase activity and its protein after treatment with YH439. Unlike competitive inhibitors of CYP2E1, YH439 rapidly (within 2 h) decreased the level of CYP2E1 mRNA, while malotilate, a structural analog of YH439, slightly suppressed its level. Nuclear run-on transcription analyses at 2, 4, and 8 h post-YH439 administration revealed that the inhibition of CYP2E1 by YH439 is at the level of transcription, indicating that YH439 is a new class of CYP2E1 inhibitor. Our data demonstrate that YH439 is a powerful inhibitor of CYP2E1 expression and is thus potentially useful as a pharmacological tool to study CYP2E1 function as well as a potential therapeutic agent.

Ethanol induces CYP2E1 by protein stabilization. Role of ubiquitin conjugation in the rapid degradation of CYP2E1

In the present study, we demonstrate that ethanol induces CYP2E1 by protein stabilization in vivo. The control half-life of CYP2E1 was determined to be 6-7 h followed by a slower secondary phase. The half-life of ethanol-stabilized CYP2E1 was calculated to be 38 h. The mechanism underlying the rapid degradation of CYP2E1 was also investigated and appears to involve the ubiquitin-proteasome proteolytic pathway. An in vitro assay using the cytosolic fraction was developed to further characterize CYP2E1 degradation. Using this assay, 40-50% loss of CYP2E1 was observed in 1 h, coincident with the formation of high M(r) ubiquitin-CYP2E1 conjugates. At concentrations approximating those found in vivo, ethanol protects CYP2E1 from cytosolic degradation. No loss of CYP2B1/2 was observed under identical conditions, suggesting that this reaction is specific for certain P-450s which are rapidly turned over.

Characterization and differential expression of protein kinase C isoforms in PC12 cells. Differentiation parallels an increase in PKC beta II

Nerve growth factor (NGF) treatment of PC12 cells induced a 2.8-fold increase in protein kinase C activity concomitant with differentiation and acquisition of neuritis. PKC protein isoforms were separated by sequential chromatography on DEAE-Sephacel/hydroxylapatite. A broad peak of PKC activity eluted which corresponded to the alpha PKC isoform. In control cells, message for all six PKC isoforms was detected and expressed as epsilon greater than zeta = gamma greater than delta greater than beta greater than alpha. Western blot of whole cell lysates revealed a large increase in the beta II, while slight changes were observed for the other five PKC isoforms during treatment (1-14 days) with NGF (50 ng/ml). In parallel, coordinate changes in the expression of the individual transcripts for the six isoforms occurred during NGF treatment. Induction and accumulation of PKC beta II may play a role in maintenance of neuronal morphology.

[Clinical reevaluation of continuous intravenous infusion of 5-fluorouracil--plasma concentrations and clinical dose by continuous intravenous and 60-min infusions]

Daily and intermittent continuous intravenous infusions [by gravity drip, (IVG) or infusion pump, (IVP)] and intermittent short-time intravenous drip infusion of 5-FU were carried out on advanced cancer patients. The MTD and dose-limiting toxicity were investigated in relation to the plasma concentrations of 5-FU determined by HPLC. Responses in eleven patients receiving IVG administration daily at 8-21 mg/kg/day were NC, but those given 5-FU alone showed no adverse reactions. Plasma concentrations were too low to be determined. In 9 patients receiving IVG or IVP administration weekly at 60 mg/kg for 24 hr, 1 of the 5 evaluable patients showed reduced hepatic metastatic lesions. One of 4 patients receiving IVP administration weekly at 120 mg/kg for 48 hr showed a disappearance of metastatic lesions in the skeletal muscle, but bone marrow suppression was observed as dose-limiting toxicity. Pharmacokinetics were more stable in IVP than in IVG with less individual difference in the plasma concentrations. Among the outpatients receiving short-time iv, IVG administration once or twice a week, 2 patients given weekly administrations at 20 mg/kg for 60 min showed slight adverse reactions. In 6 patients given high-dose administrations, bone marrow suppression was observed. When pharmacokinetics in the patients given 5-FU for 60 min were compared between the IVG and IVP groups, there were individual differences in plasma concentrations, but the differences were not significant. It was concluded from above results that the following practical dose schedules would be recommendable: 60 mg/kg for 24hr/week by IVP for inpatients and 20 mg/kg for 60 min/week by IVG for outpatients.

Portal blood flow: measurement with MR imaging

Portal blood flow was measured by means of direct bolus imaging (DBI), a method of measuring flow velocity with magnetic resonance imaging. DBI allows immediate visualization of fluid movement, thereby enabling calculation of a flow velocity from fluid displacement. In a study of 14 healthy male volunteers, portal blood flow was measured with electrocardiographic gating during the 18 seconds subjects could suspend respiration. These measurements showed a close correlation (r = .968) with those obtained by means of Doppler ultrasound (US). Increases in portal blood flow after oral administration of ethanol and glucose were measured with DBI. Glucose caused a statistically greater increase in portal blood flow volume in healthy control subjects than in patients with chronic hepatitis. Blood sugar, on the other hand, showed a significantly greater increase in these patients, possibly reflecting the greater vascular resistance of the liver. DBI is a useful noninvasive method of measuring portal blood flow without the limitations imposed on Doppler US by obesity and intestinal gas.

[Effect of vasopressin on rabbit hepatic energy metabolism evaluated using in vivo P-31 magnetic resonance spectroscopy]

Changes in metabolic state of rabbit livers after administration of vasopressin (10 mU/kg/min d.i.v.) were evaluated using in vivo P-31 magnetic resonance (MR) spectroscopy. Targets were nine normal control rabbits and eight with chronically carbon tetrachloride-damaged livers. A 2.0 Tesla whole-body MR imager was used for measurement. After administration of vasopressin, liver spectroscopy showed a mild ischemic pattern. The inorganic phosphate peak increased statistically significantly (p less than 0.05) both in the normal control group and in the damaged-liver group (20% and 16% above base line value respectively). In the normal control group, there was a statistically significant decrease (p less than 0.05) in the ATP peak to 18% below the base line value while the PME (phosphomonoester) peak increased slightly (about 10%); there was little change in the damaged-liver group. It was thought that the difference between the two groups was due to differences in blood flow mechanism and liver metabolism. Magnetic resonance spectroscopy was considered to be useful in studying the detailed changes in metabolic state of rabbit liver after administration of vasopressin.

[Experimental study of periodontal tissue regeneration using biodegradable membranes]

This study was designed to investigate the effect on new attachment formation using a biodegradable membrane as a barrier to the regeneration of periodontal tissue. One-wall wide periodontal osseous defects with exposed root surfaces were prepared in three adult mongrel dogs. After surgical debridement of the periodontal defects, 3 types of biodegradable membranes, [Poly(L-lactic acid); (P-L-LA)] membrane, [Poly(lactic acid-co-glycolic acid); (PLGA)] (81: 19 mole%) membrane and PLGA (50: 50 mole%) membrane, were arranged to cover the denuded root surfaces. Specimen blocks were removed 8 weeks postoperatively for histological evaluation of their effect on the regeneration of periodontal tissue. The results were as follows: 1. Gingival regions containing P-L-LA or PLGA (81: 19 mole%) membranes showed delayed wound healing macroscopically. 2. Almost all P-L-LA membranes were present in the experimental sites failing to be resorbed during the 8-week experimental period. PLGA (81: 19 mole%) membranes were also present but showed with some degree of resorption and fragility, while PLGA (50: 50 mole%) membranes were completely resorbed. 3. This showed that the membranes used in this experiment are possible barriers to the generation of new attachment. It is important to make sure keeping the membrane. 4. There was no relationship between osteogenesis and cementogenesis. It seems that osteogenesis was depressed by membrane shrinkage and the gingival pressure which limited "the regenerative space of bone." 5. Moderate resorption was observed on the root surface, and new cementum was formed at the resorbed surface. 6. Ankylosis was observed between the new cementum and bone at the experimental sites. Newly formed cementum was seen on coronal sections of this area.

[Measurement of portal blood flow with magnetic resonance imaging]

A new method for measuring portal blood flow using magnetic resonance imaging has been developed. Flow velocities are calculated from distances that are directly visualized using a new pulse sequence. In a phantom study, the measured flow rates showed a close correlation (r = 0.9996) with actual flow rates in the range 4.7 cm/sec to 22.8 cm/sec. In a study using volunteers, portal blood flow was quickly measured (about 18 seconds) using electrocardiographic gating. These measurements were compared with those obtained by Doppler ultrasound, with which they showed a close correlation in flow velocity (r = 0.968) and flow volume (r = 0.936). This method allows reasonably accurate quantitative analysis of portal blood flow in patients in whom the Doppler method can not be used because of obesity or intestinal gas.

Central signals of gallstones in magnetic resonance imaging

The magnetic resonance imaging of gallstones was studied in 34 patients. Diagnosis of the gallstones using magnetic resonance imaging was possible in 29 patients (85%). The gallstones showed as no-signal areas in all cases, with relatively strong signals being detected from the center of the stones in six cases. Postoperative studies showed the stones with the central signals to be of the so-called mixed stone type, in which the central area consists of cholesterol with a radiating structure. The central signal was thought to originate in water that accumulates in the central cavity of the stone, the cavity not being isolated from the exterior of the stone and there being a passage of fluids. The central signal is a characteristic indication of the stone's structure.

Portal hemodynamics in patients with hepatocellular carcinoma

The protal blood flow was assessed in 46 patients with hepatocellular carcinoma, 81 with cirrhosis, and 110 control subjects using an ultrasonic B-mode pulsed Doppler duplex system. The cross-sectional area of the portal vein was increased, and the velocity of portal blood flow was decreased in hepatocellular carcinoma and cirrhosis, whereas the blood flow volume was not significantly different. A significant decrease in portal blood flow was found in hepatocellular carcinoma only when at least three of the four major branches of the portal vein were occluded. The change in portal hemodynamics before and after transcatheter arterial embolization (TAE) was investigated. Immediately after TAE, neither portal venous pressure nor portal blood flow showed any constant trend. The portal blood flow reached a peak 1 week after TAE and then returned to its former value after 3-4 weeks, while all cases with poor prognoses showed a drop in portal blood flow after TAE.

Dietary risk factors of stroke and hypertension in Japan -- Part 2: Validity of urinalysis for dietary salt and protein intakes under a field condition

Utility of urinalysis as a method for estimating dietary salt and protein intakes was examined in volunteers from farming and fishing villages in Japan and the data was compared to findings in a survey on diets. We found that partial urine samples and even a fasting single spot urine in the a.m. could serve as valid substitutes for 24-hour (hr) urine collections. Further, significant correlations were obtained between levels of salt in the diet estimated by survey interviews and urinary sodium (Na) and between interview-estimated dietary total or animal protein and urinary inorganic sulfate (SO4). In comparative studies between farming and fishing villages, almost the same findings, higher salt in a farming village and higher animal protein in a fishing village, were obtained in the urinalysis and the survey on diets. These findings clearly indicate that urinalysis, as a method for estimating dietary salt and protein intake in population surveys, has distinct advantages.

Dietary risk factors of stroke and hypertension in Japan -- Part 1: Methodological assessment of urinalysis for dietary salt and protein intakes

In our attempt to design a method which would be more reliable than dietary survey interviews when estimating salt and protein intakes in a population survey, a urinalysis-related study was done on volunteers. Urinary sodium (Na), urea nitrogen (UN) and inorganic sulfate (SO4), all indices of dietary salt, protein and sulfoamino acids, respectively, were confirmed to reflect the nutritional condition. Interaction between salt and protein was not observed at least at the dietary levels used in the present study (for salt, 0.33 and 0.1 g/kg body weight/day; for protein, 1.6 and 0.7 g/kg body weight/day). Excretion of components was delayed several days or more after dietary ingestion, and nutritional estimation by urinalysis, therefore, may not be so much affected by daily variables in the diet intake. Further, partial urine samples proved to have a highly significant correlation with 24-hour (hr) urine, as for urinary Na, potassium (K), SO4, UN and their creatinine (Cr) ratios, thus indicating the availability of partial urine samples as substitutes for 24-hr urine specimens. Thus, urinalysis is a more readily facilitated, more scientific and more quantitative method for epidemiological nutritional surveys.

Dietary risk factors of stroke and hypertension in Japan -- Part 3: Comparative study on risk factors between farming and fishing villages in japan

General medical examinations were performed in two rural areas of Shimane Prefecture in Japan, one was a farming village and the other a fishing village where incidences of death due to stroke differed, higher in the former and lower in the latter. Comparisons were made on salt and protein intake by analyzing the fasting single spot urine collected in the morning and by blood tests. Urine samples were analyzed for sodium (Na), potassium (K), urea nitrogen (UN), inorganic sulfate (SO4) and creatinine (Cr) and blood samples for cholesterol (Chl), triglyceride (TG), hematocrit (Ht) and hemoglobin (Hb). Blood pressure, Na/Cr, Na/K and Ht were higher in the farming village and K/Cr, UN/Cr, SO4/Cr, SO4/UN, Chl and TG were higher in the fishing village. These findings indicate the higher salt intake and lower intake of K, animal protein and fat in the farming village. This typical dietary pattern of the Japanese may explain the higher incidence of hypertension and stroke in the farming village.

[Clinical evaluation of cefmetazole in the dermatologic field]

The therapeutic efficacy and safety of cefmetazole, a cephamycin-derived antibiotic in an injectable form were evaluated in patients with pyogenic infection in the dermatological field. Especially, it was found to be extremely effective for the skin diseases due to staphylococci or streptococci. The results obtained were the following; marked improvement in 18 cases and moderate improvement in 34 cases out of 61 cases, attaining efficacy of 86.7%. Side effects were noted as the rise of GOT and GPT in 3 cases, which were normalized by ceasing its further administration. The MIC of cefmetazole against Staphylococcus aureus isolated out of foci was 0.39-6.25 microgram/ml, while those of CEZ, CXM and ABPC used as the controls exceeded 50 microgram/ml in some cases. It is considered thus, that cefmetazole, is superior to these other antibiotics also in terms of MIC.