115 CYTOLOGICAL ANALYSIS OF HEPATIC GENE EXPRESSION AND IMMUNOLOGICAL RESPONSE OF MHC ANTIGENS IN MOUSE AMNIOTIC EPITHELIAL CELLS

Human amniotic epithelial cells (hAECs) have been reported to have unique properties. They express almost no class I and class II MHC antigens and lack response to interferon-γ (IFN-γ) which mediates the expression of those MHC molecules. Moreover, hAECs express some genes characteristic of hepatic cells. Therefore, hAECs seem to have multipotency and are expected to substitute for hepatic tissues in part. We aimed to develop the experimental model for investigating AECs in mice (mAECs). In this study, we examined the induction of MHC molecules by IFN-γ and the hepatic gene expression in mAECs. Murine amniotic membranes were collected from C57BL/6J females at 17.5 days of gestation. They were digested by 0.03% hyaluronidase followed by 0.2% collagenase treatment. Dissociated mAECs were cultured on dishes in DMEM supplemented with 10% FBS at 37°C under 5%CO2 in air. Embryonic fibroblasts (EFs) collected from C57BL/6J fetuses at 13.5 dpc were cultured in the same condition as mAECs. In Experiment I, the effect of IFN-γ on induction of MHC molecules in mAECs was examined. mAECs and EFs cultured in the presence or absence of IFN-γ at 1 × 103 U mL−1 for 72 h were recovered and incubated with FITC-conjugated antibodies against mouse H-2 MHC class I or I-A/I-E MHC class II antigens. The cells were analyzed by flow cytometry. In Experiment II, the expression of the genes in mAECs was examined by RT-PCR. mRNA was purified from adult liver, EFs, fresh mAECs, and mAECs cultured for 5 days. As the genes characteristic for hepatic cells, HNF-3α, HNF-3β, HNF-3γ, HNF-4, transthyretin (TTR), albumin, α-fetoprotein (AFP), glucose-6-phosphatase (G6P), and asialoglycoprotein receptor-1 (Asgr1) were examined. In Experiment I, cell-surface expression of class I and class II MHC antigens in response to IFN-γ was observed weakly in mAECs as compared to EFs, suggesting different property in hAECs which lack the expression of those antigens. In Experiment II, RT-PCR analysis showed that all of the genes except G6P were expressed in fresh mAECs. However, the expression of transcription factors such as HNF-3α, HNF-3β, HNF-4, and TTR, serum proteins such as albumin and AFP, and Asgr1 decreased after in vitro culture, contrary to the case of hAECs in which, for example, albumin appeared after cultivation. In conclusion, it was evident that mAECs have quite different properties, both in the inductivity of MHC molecules and the expression of hepatic genes, from hAECs. This work was supported by Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence of the JST, and by a Grant-in-Aid for the 21st Century COE Program of the Japan MEXT.

Cellular prion protein regulates intracellular hydrogen peroxide level and prevents copper-induced apoptosis

The function of cellular prion protein (PrPC), which is a copper binding protein, remains unclear. To elucidate the mechanisms in which PrPC is involved in neuroprotection, we compared death signals in prion protein gene-deficient (Prnp-/-) primary cerebellar granular neurons (CGNs) to those with wild-type (WT) CGNs. When copper was exposed to these CGNs, ZrchI, and Rikn Prnp-/- CGNs were more sensitized and underwent apoptotic cell death more readily than WT CGNs. Furthermore, the level of intracellular hydrogen peroxide (H2O2) in WT CGNs increased by copper toxicity, whereas those in ZrchI and Rikn Prnp-/- CGNs did not. These results suggest that PrPC modulates the intracellular H2O2 level as a copper-binding protein to protect CGNs from apoptotic cell death possibly due to inhibiting a Fenton reaction.

Targeted disruption of the IA-2beta gene causes glucose intolerance and impairs insulin secretion but does not prevent the development of diabetes in NOD mice

Insulinoma-associated protein (IA)-2beta, also known as phogrin, is an enzymatically inactive member of the transmembrane protein tyrosine phosphatase family and is located in dense-core secretory vesicles. In patients with type 1 diabetes, autoantibodies to IA-2beta appear years before the development of clinical disease. The genomic structure and function of IA-2beta, however, is not known. In the present study, we determined the genomic structure of IA-2beta and found that both human and mouse IA-2beta consist of 23 exons and span approximately 1,000 and 800 kb, respectively. With this information, we prepared a targeting construct and inactivated the mouse IA-2beta gene as demonstrated by lack of IA-2beta mRNA and protein expression. The IA-2beta(-/-) mice, in contrast to wild-type controls, showed mild glucose intolerance and impaired glucose-stimulated insulin secretion. Knockout of the IA-2beta gene in NOD mice, the most widely studied animal model for human type 1 diabetes, failed to prevent the development of cyclophosphamide-induced diabetes. We conclude that IA-2beta is involved in insulin secretion, but despite its importance as a major autoantigen in human type 1 diabetes, it is not required for the development of diabetes in NOD mice.

Exercise blood pressure in young adults as a predictor of future blood pressure: a 12-year follow-up of medical school graduates

It has not been fully clarified whether exercise blood pressure (BP) in young adult men and women is useful to predict future BP, especially in Asian people. A long-term prospective study was conducted in graduates of a medical school in Japan; 138 men and 76 women whose mean age was 19.8 and 19.2, respectively, at baseline. A 5-min exercise tolerance test was performed at baseline, and BP immediately after exercise was measured. BP at 50% intensity exercise was also calculated. Multiple regression analysis was carried out to clarify the relationship of exercise BP at baseline to follow-up BP after an average of 12 years. In multivariate-adjusted models, the relationship of systolic blood pressure (SBP) at follow-up was stronger to SBP immediately after exercise (F=7.7, P=0.006) than to resting SBP (F=3.7, P=0.055) in men. The models in men showed that SBP immediately after exercise was a stronger predictor of follow-up SBP than SBP at 50% intensity exercise, and the results were similar for diastolic blood pressure (DBP) in men. For SBP in women, resting SBP was the strongest predictor of follow-up SBP (F=14.3, P<0.001), and exercise SBP was not significant predictor. For DBP in women, any DBP at rest or after exercise was not significantly related to DBP at follow-up. In young adult men, SBP and DBP immediately after exercise would be a stronger predictor of future SBP and DBP rather than BP at rest. However, in young adult women, resting SBP rather than exercise SBP would be better to predict future SBP.

Hyperbaric Oxygen Enhances the Expression of Prion Protein and Heat Shock Protein 70 in a Mouse Neuroblastoma Cell Line

1. Cellular prion protein, PrP(C), is a ubiquitous glycoprotein strongly expressed in neurons with an as yet unknown biological function. In previous studies, we demonstrated that PrP(C) could be regulated by heat shock stress, implying that it might be a stress-responsive protein. Hyperbaric oxygen (HBO) administration is a well-defined model for the study of oxidative stress. 2. This study investigated the effect of HBO on PrP(C) and Hsp 70 expression in mouse neuroblastoma cell lines (N18), assessing the expression of PrP(C) and Hsp 70 using RT-PCR and Western blotting. HBO administration resulted in a time- and dose-dependent increase in PrP(C) and Hsp70 expression in N18 cells at both mRNA and protein levels, with a concomitant upregulation of c-Jun N-terminal kinase (JNK). 3. Under HBO treatment, luciferase reporter constructs of the rat PrP(C) promoter, containing the heat shock element (HSE) also present in Hsp70, expressed higher luciferase activity (3- to 10-fold) than those constructs without HSE. 4. In summary, these data suggest that PrP(C) and Hsp 70 may be regulated by HBO, through the activation of JNK. Thus, the activated heat shock transcriptional factor 1, phosphorylated by JNK interacted with HSE in the promoter of PrP(C) resulted in increased gene expression. These findings are vital for future therapeutic approaches in transmissible spongiform encephalopathies and the understanding of the function of the PrP(C).

Prion protein suppresses perturbation of cellular copper homeostasis under oxidative conditions

Prion protein (PrP) binds copper and exhibits superoxide dismutase-like activity, while the roles of PrP in copper homeostasis remain controversial. Using Zeeman graphite furnace atomic absorption spectroscopy, we quantified copper levels in immortalized PrP gene (Prnp)-deficient neuronal cells transfected with Prnp and/or Prnd, which encodes PrP-like protein (PrPLP/Dpl), in the presence or absence of oxidative stress induced by serum deprivation. In the presence of serum, copper levels were not significantly affected by the expression of PrP and/or PrPLP/Dpl, whereas serum deprivation induced a decrease in copper levels that was inhibited by PrP but not by PrPLP/Dpl. The inhibitory effect of PrP on the decrease of copper levels was prevented by overexpression of PrPLP/Dpl. These findings indicate that PrP specifically stabilizes copper homeostasis, which is perturbed under oxidative conditions, while PrPLP/Dpl overexpression prevents PrP function in copper homeostasis, suggesting an interaction of PrP and PrPLP/Dpl and distinct functions between PrP and PrPLP/Dpl on metal homeostasis. Taken together, these results strongly suggest that PrP, in addition to its antioxidant properties, plays a role in stabilizing cellular copper homeostasis under oxidative conditions.

Suppressor mechanism of serum thymic factor on tumor necrosis factor-alpha-induced apoptosis in the mouse pancreatic beta-cell line

Tumor necrosis factor-alpha (TNF-alpha) is a cytokine considered to play a key role in beta-cell destruction in insulin-dependent diabetes mellitus (IDDM). Serum thymic factor (Facteur thymique serique; FTS) is a nonapeptide thymus hormone known to inhibit IDDM in a mouse model. In this study, the effect of TNF-alpha on the murine pancreatic beta-cell line MIN6 was examined. Cell shrinkage and detachment were seen in cells treated with 0-50 ng/ml TNF-alpha for 12h. Oligonucleosomal DNA fragmentation was determined from non-adherent cells, indicating that the TNF-alpha-induced cell destruction was attributed to apoptosis. Fragmented DNA was quantified by enzyme-linked immunosorbent assay to measure the amount of histone-bound oligonucleosomes. FTS was treated with TNF-alpha and the percentage of fragmented DNA was analyzed. The data indicate a distinct reduction of fragmented DNA at a concentration of 1 ng/ml FTS. Expression of TNF receptor I, inducible form of nitric oxide synthase (iNOS), interleukin-1 beta-converting enzyme (ICE), Bcl-2, and nuclear factor kappa B (NF-kappa B) was analyzed by reverse transcriptase-polymerase chain reaction to investigate the suppressor mechanism of FTS on TNF-alpha-induced apoptosis. FTS treatment suppressed the expression of iNOS and Bcl-2 mRNA in TNF-alpha-treated cells. The expression of NF-kappa B mRNA in TNF-alpha-treated cells was enhanced after FTS treatment, while that of ICE mRNA did not change in TNF-alpha-treated cells with or without FTS treatment. These results suggest that the inhibition of MIN6 cell death by FTS on TNF-alpha-induced apoptosis is caused by a negative feedback mechanism involving the inhibition of iNOS induction.

Transfection of prion protein gene suppresses coxsackievirus B3 replication in prion protein gene-deficient cells

The susceptibility of prion protein gene (Prnp)-null cells to coxsackievirus B3 (CVB3) was investigated. Primary cultures of murine Prnp(-/-) brain cells were more sensitive to CVBs than corresponding cells from wild-type mice. The viral susceptibility of a Prnp-null cell line (HpL3-4) derived from the murine hippocampus was compared with that of two established cell lines (HeLa and HEp-2) that are widely employed for CVB3 studies. After infection with CVB3, HpL3-4 cells showed a very rapid and complete cytopathic effect (CPE). CPE developed earlier and viruses replicated at higher titres in HpL3-4 cells compared with HeLa and HEp-2 cells. Under a semi-solid medium, plaques developed rapidly in CVB3-infected HpL3-4 cells. To confirm the effect of Prnp on virus infection, a Prnp(-/-) cell line and a Prnp-transfected neuronal cell line were analysed. The replication and release of infectious particles of CVB3 in Prnp(-/-) cells were significantly more effective than those of the Prnp-transfected cell line. Levels of type I interferon (IFN) after CVB3 infection were higher in the Prnp-transfected cell line than in Prnp(-/-) cells, whereas apoptotic cells were more obvious in the Prnp(-/-) cells than in those of the Prnp-transfected cell line. These findings suggest that the absence of Prnp retards the induction of CVB3-induced IFNs, resulting in an enhanced CVB3 production and apoptotic cell death. Furthermore, our data indicate that the HpL3-4 cell line may provide a novel and sensitive system for isolation of CVB3 from clinical specimens.

339CORRELATION BETWEEN FOLLICLE SIZE AND QUALITY OF OOCYTES FROM THE SUPEROVULATED CYNOMOLGUS MONKEY

Variability in the superovulatory response continues to be one of the most frustrating problems with the application of assisted reproductive technologies in non-human primates. Superstimulation of donor animals with equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) is widely used, but individual responses to these hormones vary widely. In human in vitro fertilization, follicle size is commonly used as a marker to determine the timing of hCG treatment in order to acquire oocytes matured in vivo. Incorporation of techniques designed to control follicular size in humans may improve superstimulatory response in non-human primates. In this study, we measured follicle size and examined oocyte quality in Cynomologus Monkeys superstimulated as described below. On the first day of spontaneous menses, monkeys were treated with long-acting GnRH (Luprin: Takeda Pharm, Co. Ltd., Osaka, Japan;; Day 0). A dose of 25IU/kg/day eCG (Serotoropin;; Teikokuzoki Pharm, Co. Ltd., Tokyo, Japan) was administered i.m. from Day 1 to Day 9, followed by 200IUkg−1 hCG (Puberogen;; Sankyo Pharm, Co. Ltd., Tokyo, Japan) i.m. on Day 10. Dominant follicle sizes were measured on Days 7 and 9 by ultrasonography. Oocytes were collected by laparoscopy in anesthetized monkeys 40h after the hCG injection. Oocytes were classified by nuclear status. Immature oocytes at the stages of germinal vesicles (GV) and metaphase (MI) were cultured until reaching the stage of Metaphase II (MII). Matured oocytes (MII) were fertilized by ICSI and cultured for 7 days. At the end of culture, the developmental stage of oocytes was examined. The ovaries with different-sized follicles on Day 7 were divided into two groups;; ovaries with large follicles (&gt;4.5mm) were in the first group and ovaries with small follicles (&lt;4.0mm) were in the second group. On Day 9, follicles in first group grew to more than 5.0mm and follicles in second group remained less than 5.0mm. Sixty-two percent of oocytes from follicles in first group were at MI or MII stage, while only 15% of oocytes in second group reached the MI or MII stage. After ICSI, 42% of MII oocytes from first group developed to the blastocyst stage, while no blastocyts were observed in second group. These results suggest that the size of dominant follicle was a limiting factor for the developmental ability of oocytes in vitro. For production of Cynomolgus monkey blastocysts derived from ICSI, the diameter of dominant follicle was required to be at least 5mm before hCG in order to collect MI and MII oocytes. Incorporation of hormonal treatments designed to optimize follicular size probably reduced the variability in quality of oocytes. Therefore, we expect that an adjustment of dose and duration of eCG and hCG treatment may improve developmental ability of oocytes from follicles that had not reached 5mm.

72EFFECTS OF GENE EXPRESSION IN BOVINE EMBRYOS RECONSTRUCTED WITH FIBROBLASTS TRANSFECTED WITH LUCIFERASE GENE ON THE SUBSEQUENT DEVELOPMENT

During embryo development, embryonic gene activation (EGA) is one of the first critical events. Inappropriate EGA results in failure of further development. We have reported that gene expression in bovine embryos reconstructed with fibroblasts begins at 48 hours postfusion (hpf) and reaches a maximum level at 60hpf as detected by their bioluminescence following injection of chicken β-actin/firefly luciferase fusion gene (β-act/luc+) into their nuclei (Saeki et al., 2001 Theriogenology 55, 289). In the present study, effects of gene expression in embryos reconstructed with bovine fibroblasts transfected with luciferase gene on their subsequent development to the blastocyst stage were examined. Cultured bovine fibroblasts taken from an ear of a female calf were transfected with plasmid containing β-act/luc+/IRES/EGFP and neor using GeneJammer (StrataGene, La Jolla, CA, USA). Neomycin-resistant cells were selected by culturing with G418. Then, EGFP-positive colonies were further selected under fluorescence microscopy to obtain stably transfected cells. The transfected cells were cultured for several passages. Growing (50 to 60% confluence, GCs) and serum-starved cells (SCs) were used as donor cells. In vitro-matured bovine oocytes derived from slaughterhouse ovaries were enucleated at 20h post maturation. Enucleated oocytes were electrofused with the cells, and activated with calcium ionophore and cycloheximide. Luminescence in the embryos was detected with an imaging photon counter at 0 and 60hpf. Luminescence-positive (P) and -negative (N) embryos were cultured separately at each detection time. Embryos were cultured until 168hpf, and examined for cleavage and blastocyst development. Experiments were repeated 3 times, and totals of 91 and 123 embryos were reconstructed with GCs and SCs, respectively. Data were analyzed with Fisher’s PLSD test following ANOVA by Stat View software (Ver. 5.0). At 0hpf, luminescence was detected in 55 and 4% of embryos reconstructed with GCs and SCs, respectively. At 60hpf, luminescence was detected in 47 and 28% of P and N embryos with GCs, and 17 and 40% of P and N embryos with SCs at 0hpf, respectively. Cleavage rates were not different among groups (P&gt;0.05). Blastocysts were obtained only from the groups of embryos that were N at 0hpf and P at 60hpf (8% with GCs and 17% with SCs). No embryos in the other groups developed to the blastocyst stage. These results suggest that appropriate gene expression in embryos reconstructed with somatic cells is important for their subsequent development and that detecting the reporter gene expression can be used for selection of viable cloned embryos.

Tumor necrosis factor attenuates prion protein-deficient neuronal cell death by increases in anti-apoptotic Bcl-2 family proteins

Prion protein gene (Prnp)-deficient(Prnp(-/-)) neuronal cells are more susceptible to serum deprivation compared to Prnp(+/+) neuronal cells. However, little is known about the cell death of Prnp(-/-) neuronal cells under serum deprivation. In this study, as a known neuroprotective agent we analyzed the effect of tumor necrosis factor-alpha (TNF-alpha) on the cell death of Prnp(-/-) neuronal cells. Although expression of Bcl-2 and Bcl-x(L) decreased in a time-dependent manner under serum deprivation, treatment with TNF-alpha protected Prnp(-/-) neuronal cells from serum deprivation with an increase in anti-apoptotic proteins Bcl-2 and Bcl-x(L). Nuclear morphological analysis using fluorescence microscopy and flow cytometry analysis showed that gene transfer of bcl-2 or bcl-x(L) significantly inhibited apoptosis induced by serum deprivation. These findings indicate that TNF-alpha attenuated cell death of Prnp(-/-) neuronal cells by induction of Bcl-2 and Bcl-x(L),and that decreases in Bcl-2 and Bcl-x(L) played crucial roles in the apoptosis of Prnp(-/-) neuronal cells.

Analysis of T-cell receptor Vbeta gene from infiltrating T cells in insulitis and myocarditis in encephalomyocarditis virus-infected BALB/C mice

Encephalomyocarditis (EMC) virus induces insulin-dependent diabetes and myocarditis in several strains of mice. The T-cell receptor (TCR) Vbeta genes of infiltrating T cells in the pancreas and myocardium of BALB/C mice infected with EMC virus D-variant (EMC-D virus) were analyzed. Using a nested two-step polymerase chain reaction (PCR), TCR Vbeta cDNAs were cloned and sequenced. Two and four kinds of TCR Vbeta clones were obtained from T cells infiltrating into the pancreas and myocardium of BALB/C mice infected with EMC-D virus, respectively. The infiltrating lymphocytes in the diabetic mice expressed Vbeta 8.1, 8.2, and 8.3 genes predominantly. Previously, the use of Vbeta 8.2 has been reported in autoimmune diseases such as murine experimental allergic encephalomyelitis (EAE) and non-obese diabetic (NOD) mouse. This study suggests that mice infected with EMC virus are a useful animal model for autoimmune diseases such as insulin-dependent diabetes.

Impairment of superoxide dismutase activation by N-terminally truncated prion protein (PrP) in PrP-deficient neuronal cell line

Previous studies have reported a neuroprotective role for cellular prion protein (PrP(C)) against apoptosis induced by serum deprivation in an immortalized prion protein gene (Prnp)-deficient neuronal cell line, but the mechanisms remain unclear. In this study, to investigate the mechanisms by which PrP(C) prevents apoptosis, the authors compared apoptosis of Prnp(-/-) cells with that of Prnp(-/-) cells expressing the wild-type PrP(C) or PrP(C) lacking N-terminal octapeptide repeat region under serum-free conditions. Re-introduction of Prnp rescued cells from apoptosis, upregulated superoxide dismutase (SOD) activity, enhanced superoxide anion elimination, and inhibited caspase-3/9 activation. On the other hand, N-terminally truncated PrP(C) enhanced apoptosis accompanied by potentiation of superoxide production and caspase-3/9 activation due to inhibition of SOD. These results suggest that PrP(C) protects Prnp(-/-) cells from apoptosis via superoxide- and caspase-3/9-dependent pathways by upregulating SOD activity. Furthermore, the octapeptide repeat region of PrP(C) plays an essential role in regulating apoptosis and SOD activity.

Expression of normal cellular prion protein (PrP(c)) on T lymphocytes and the effect of copper ion: Analysis by wild-type and prion protein gene-deficient mice

The purpose of this report was to determine the effect of prion protein (PrP) gene disruption on T lymphocyte function. Previous studies have suggested that normal cellular prion protein (PrP(c)) binds to copper and Cu(2+) is essential for interleukin-2 (IL-2) mRNA synthesis. In this study, IL-2 mRNA levels in a copper-deficient condition were investigated using T lymphocytes from prion protein gene-deficient (PrP(0/0)) and wild-type mice. Results showed that Cu(2+) deficiency had no effect on PrP(c) expression in Con A-activated splenocytes. However, a delay in IL-2 gene expression was observed in PrP(0/0) mouse T lymphocyte cultures using Con A and Cu(2+)-chelator. These results suggest that PrP(c) expression may play an important role in rapid Cu(2+) transfer in T lymphocytes. The rapid transfer of Cu(2+) in murine T lymphocytes could be one of the normal functions of PrP(c).

Absence of superoxide dismutase activity in a soluble cellular isoform of prion protein produced by baculovirus expression system

A method for expression and purification of a soluble form of histidine (HIS)-tagged murine prion protein (bacMuPrP), which lacks the entire C-terminal cleavage and glycosyl phosphatidyl inositol (GPI) addition site, has been developed using a recombinant baculovirus expression system and purification with Ni-NTA agarose affinity chromatography. In mammalian sources, PrP(C) is attached to the cell membrane by a GPI anchor. However, in our system, bacMuPrP was secreted into the media, enabling its easy purification in abundance. Indirect immunofluorescence studies and immunoblot analysis localized not in cell membrane but in the perinuclear endoplasmic reticulum region in cells and is secreted into the media. Tunicamycin treatment revealed non-glycosylated proteins were secreted into the media, suggesting that glycosylation is not necessary for bacMuPrP secretion. Density-gradient sedimentation analysis demonstrated a sedimentation coefficient of secretory bacMuPrP as 2.3 S, indicating a monomeric form. Although affinity-purified PrP from mouse brain or recombinant prion protein (PrP) produced by Escherichia coli and refolded in the presence of copper has been reported to display superoxide dismutase (SOD) activity, bacMuPrP did not show SOD activity. These results suggest that bacMuPrP has a different biochemical and biophysical characterization from mammalian and bacterial-derived PrP. Furthermore, this simple expression system may provide an adequate source for structural, functional, and biochemical analyses of PrP.

Relationships between bacterial tolerance levels and forms of copper and zinc in soils

The effects of various fractions of copper (Cu) and zinc (Zn) on soil bacteria were evaluated by the heavy metal tolerance level of the bacterial community (IC50) in soil samples collected near a mine. The IC50 values had no relationship with the total concentrations of Zn and Cu in the soils, but were weakly correlated with the 0.05 M CaCl2-extractable form of each metal in the soils (Cu: R2 = 0.670, p < 0.01; Zn: R2 = 0.453, p < 0.05). It was found that the IC50 correlated strongly with the total concentration of each metal in the extracts from water-saturated soil samples, described below as "soil solution" (Cu: R2 = 0.789, p < 0.01; Zn: R2 = 0.617, p < 0.01). The speciation of these metals in the soil solutions was estimated using an equilibrium thermodynamic computer model, SOILCHEM. Simulated free Cu ion ranged from 18 to 98% of total Cu, and organic complexes of Cu ranged from < 1 to 56%. In all samples, Zn existing as the free ion was estimated to be more than 80% of total Zn in the soil solutions. The IC50 values were also correlated with the estimated free metal ion activities, but with slightly lower correlation coefficients than found for total concentration in the soil solutions (Cu: R2 = 0.735, p < 0.01; Zn: R2 = 0.610, p < 0.01). The results suggest that not only high metal ion activities, but also total dissolved metal concentrations in soil solutions may affect the bacterial community.

Molecular modulation of expression of prion protein by heat shock

Prion diseases (also known as transmissible spongiform encephalopathies) are associated with the conversion of the normal cellular form of the prion protein (PrPC) to an abnormal scrapie-isoform (PrP(Sc). The conversion of PrP(C) to PrP(Sc) is post-translational and is owing to protein conformational change. This has led to the hypothesis that molecular chaperones may be involved in the folding of prion proteins, and hence the disease process. By treating human NT-2 cells with heat-shock stress, we found that both the mRNA levels for prion protein (PrP) and heat shock protein 70 (HSP70) increased simultaneously after heat treatment. Western-blot analysis of PrP also showed a two-fold increase in PrP protein level 3 after heat treatment. Furthermore, two heat-shock elements (HSEs) were located at the positions of -680 bp (HSE1; GGAACTATTCTTGACATTGCT), and -1653 bp (HSE2; TGAGAACTCAGGAAG) of the rat PrP (RaPrP) gene promoter. Luciferase reporter constructs of the RaPrP promoter with HSE expressed higher luciferase activity (10- to 15-fold) than those constructs without HSE. Electrophoretic gel mobility shift assay (EMSA) and super-shift assay confirmed the interaction of HSE1 and HSE2 with the heat-shock transcription factor-1 (HSTF-1). These results suggest that cellular stress up-regulates both the transcription and translation of PrP through interaction with the HSEs on the PrP gene promoter, resulting in an increase in protein synthesis.

Targeted disruption of the protein tyrosine phosphatase-like molecule IA-2 results in alterations in glucose tolerance tests and insulin secretion

IA-2 is a major autoantigen in type 1 diabetes. Autoantibodies to IA-2 appear years before the development of clinical disease and are being widely used as predictive markers to identify individuals at risk for developing type 1 diabetes. IA-2 is an enzymatically inactive member of the transmembrane protein tyrosine phosphatase family and is an integral component of secretory granules in neuroendocrine cells. To study its function, we generated IA-2-deficient mice. Northern and Western blot analysis showed that neither IA-2 mRNA nor protein was expressed. Physical examination of the IA-2(- /-) animals and histological examination of tissues failed to reveal any abnormalities. Nonfasting blood glucose levels, measured over 6 months, were slightly elevated in male IA-2(-/-) as compared to IA-2(+ /+) littermates, but remained within the nondiabetic range. Glucose tolerance tests, however, revealed statistically significant elevation of glucose in both male and female IA-2(-/-) mice and depressed insulin release. In vitro glucose stimulation of isolated islets showed that male and female mice carrying the disrupted gene released 48% (P < 0.001) and 42% (P < 0.01) less insulin, respectively, than mice carrying the wild-type gene. We concluded that IA-2 is involved in glucose-stimulated insulin secretion.

Comparative analysis of the prion protein open reading frame nucleotide sequences of two wild ruminants, the moufflon and golden takin

The prion protein (PrP) nucleotide sequences of two ruminants were determined in order to elucidate the differences in susceptibility to spongiform encephalopathy agents in each species. The nucleotide sequences of PrP coding regions of the moufflon and the golden takin encompassed 771 bp in length. The PrP gene sequences of the golden takin were closely related to those of sheep with one amino acid difference. The PrP gene sequence of the moufflon was identical to that of sheep. The similarities between the PrP genes of these two animals and sheep imply that the species barriers between these animals are small or non-existent. These PrP genes could be used to establish transgenic mice with higher susceptibility to prion-related diseases.

Surgically treated primary lung cancer associated with Brugada syndrome: report of a case

A 71-year-old man with primary lung cancer associated with Brugada syndrome was safely operated on following the placement of an implantable cardioverter defibrillator (ICD). During examinations for Brugada syndrome, a tumor in the apicoposterior segment of the left lung was incidentally detected by chest computed tomography. Following the implantation of an ICD, surgical treatment of the left lung tumor was scheduled. A lung biopsy was thoracoscopically performed and adenocarcinoma was diagnosed based on a frozen section analysis. A left upper lobectomy with lymph node dissection was performed through a standard posterolateral thoracotomy. Ventricular fibrillation, which occurred during the night of the first day following surgery, was successfully managed by the ICD.

Recurrent growth factor starvation promotes drug resistance in human leukaemic cells

Multi-drug resistance can be induced by various environmental stresses including an exposure to chemical drugs and X-ray irradiation. In addition, hypo-nutritive conditions are known to promote multi-drug resistance in solid tumours. To understand the importance of nutritive conditions in the development of drug resistance in non-solid tumours and to know whether a transient malnutrition could induce a permanent reduction in drug sensitivity, leukaemic cells were transiently cultured under growth factor-starved conditions. Granulocyte-macrophage colony-stimulating factor-dependent human leukaemic MO7e cells were cultured in the absence of granulocyte-macrophage colon-stimulating factor for 2 weeks, during which the majority of the cells died, and the minor viable cells were expanded in the presence of granulocyte-macrophage colon-stimulating factor for following 1 week. This procedure was repeated three times, and the surviving cells were cloned by limiting dilution. These clones underwent G1 arrest in the absence of granulocyte-macrophage colon-stimulating factor, while parental cells underwent apoptosis. Interestingly, activities of the downstream targets of granulocyte-macrophage colon-stimulating factor receptor were regulated in a granulocyte-macrophage colon-stimulating factor-independent manner, indicating that the ligand-independent activation of granulocyte-macrophage colon-stimulating factor receptor had not taken place. Moreover, the 4--7-fold increases in IC(50) for etoposide and the 2--6-fold increase in IC(90) for doxorubicin was observed. Furthermore, Bcl-2 protein expression was significantly up-regulated in the clones while no significant changes in Bax, Bcl-(xL), P-glycoprotein and Hsp70 protein expression and no consistent changes in p53 expression were detected. We propose that recurrent growth factor starvation, which may occur in vivo when stromal function is damaged after intensive chemotherapy or bone marrow occupation by malignant cells, causes selection of drug resistant leukaemia cells that will expand when the growth factor supply recovers.

Diverse effects of cytochalasin B on priming and triggering the respiratory burst activity in human neutrophils and monocytes

Cytochalasin B, despite its potent enhancing effect on superoxide (O2-) release triggered by N-formyl-methionyl-leucyl-phenylalanine (FMLP) and many other agonists, significantly inhibited O2- release triggered by interleukin 8 (IL-8) and platelet-activating factor in human neutrophils. Cytochalasin B also enhanced changes in membrane potential stimulated by FMLP but inhibited those stimulated by IL-8. Using IL-8 as a triggering agonist, we found that the priming effect of tumor necrosis factor (TNF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) on O2- release was slightly but significantly potentiated by cytochalasin B. O2- release triggered by TNF and GM-CSF was completely abolished by cytochalasin B. In contrast to these diverse effects of cytochalasin B on O2- release, changes in cytoplasmic pH stimulated by FMLP, IL-8, TNF, and GM-CSF were not or were only minimally affected by cytochalasin B. Unlike human neutrophils, human monocytes stimulated by FMLP showed inhibition of O2- release and changes in membrane potential in response to cytochalasin B, and the priming effect of TNF and GM-CSF on O2- release in human monocytes was completely abolished by cytochalasin B. These findings indicate the diverse effects of cytochalasin B on phagocytes and suggest distinct regulatory mechanisms according to the functions, agonists, and cell types.

Induction of phagocyte oxidase components during human myeloid differentiation: independent protein expression and discrepancy with the function

We investigated the content of four components of the O2(-)-producing enzyme (p47, p67, p22, and gp91) and the O2(-)-producing capacity in human myeloid cell lines. The content of the four components of the phagocyte oxidase was minimal before differentiation induction. During differentiation, expression of p22 and gp91 was at consistently low levels, even when the O2(-)-producing capacity was equivalent to that of normal neutrophils. On the other hand, p47 was consistently and rapidly induced to the level comparable to normal neutrophils. The results indicate that low expression of p22 and gp91 is sufficient to obtain normal O2- production, and that p47 might play an important regulatory role in the functional differentiation.

Activation of extracellular signal-regulated kinases and CREB/ATF-1 mediate the expression of CCAAT/enhancer binding proteins beta and -delta in preadipocytes

The essential role of CCAAT/enhancer binding proteins (C/EBPs) beta and delta for adipocyte differentiation has been clearly established. In preadipocytes, their expression is up-regulated by the activation of leukemia inhibitory factor receptor (LIF-R) and prostacyclin receptor (IP-R) via the extracellular signal-regulated kinase (ERK) pathway and cAMP production, respectively. However, the molecular mechanisms by which LIF and prostacyclin-induced signals are propagated to the nucleus and the transcription factors mediating ERK and cAMP-induced C/EBP gene expression were unknown. Here we report that both pathways share cAMP responsive element binding protein/activation transcription factor 1 (CREB/ATF-1) as common downstream effectors. LIF-R and IP-R activation induced binding of CREB and/or ATF-1 to C/EBP promoters and CREB-dependent transcription. Expression of dominant negative forms of CREB dramatically reduced the LIF- and prostacyclin-stimulated C/EBP beta and C/EBP delta expression. Upon stimulation of the IP-R, the ERK pathway was activated in a PKA-dependent manner. ERK activation by the PKA pathway was not required for CREB/ATF-1 phosphorylation but rather was necessary for CREB-dependent up-regulation of C/EBPs expression. Our findings suggest that ERK activation is required for CREB transcriptional activity, possibly by recruitment of a coactivator.

Stability after medial collateral ligament release in total knee arthroplasty

Six knees from cadavers were tested for change in stability after release of the medial collateral ligament with posterior cruciate-retaining and substituting total knee replacements. Load deformation curves of the joint were recorded in full extension and 30 degrees, 60 degrees, and 90 degrees flexion under a 10 N-m varus and valgus torque, 1.5 N-m internal and external rotational torque, and a 35 N anterior and posterior force to test stability in each knee. The intact specimen and posterior cruciate ligament-retaining total joint replacement were tested for baseline comparisons. The superficial medial collateral ligament was released, followed by release of the posterior cruciate ligament. The knee then was converted to a posterior-stabilized implant. After medial collateral ligament release, valgus laxity was statistically significantly greater at 30 degrees, 60 degrees, and 90 degrees flexion after posterior cruciate ligament sacrifice than it was when the posterior cruciate ligament was retained. The posterior-stabilizing post added little to varus and valgus stability. Small, but significant, differences were seen in internal and external rotation before and after posterior cruciate ligament sacrifice. The posterior-stabilized total knee arthroplasty was even more rotationally constrained in full extension than the knee with intact medial collateral ligament and posterior cruciate ligament.