[Experimental infection of Naegleria fowleri in mice]

Ten SPF mice (ddY, 4w-old, female) were infected by nasal instillation with an isolate of Naegleria fowleri that was first isolated from a patient with primary amoebic meningoencephalitis (PAM) in Japan. Of these mice, 2 showed clinical signs typical for PAM on the 4th day. On the next day, 5 mice became very ill and remained immobile; their movement and response to painful stimuli diminished progressively. All the infected mice were then examined histopathologically on the same day regardless of their clinical signs. Pathological changes due to invasion and/or proliferation of amoebae were observed in 5 mice with clinical signs. Swelling of the nasal mucosa and ulcerated nasal epithelium with inflammatory cells were observed. Proliferation of amoebae was detected to a lesser extent in nasal cavity including mucous membrane and nasal epithelium. Olfactory lobes and arteriolar hemisphere were necrotic with haemorrhage and filled with amoebae. From these findings the pathogenicity of the isolate was confirmed to develop PAM in experimental animals. It was also observed that the olfactory neuroepithelium was the route of invasion in PAM due to N. fowleri and consequently migration occurred through olfactory lobes into the cerebrum.

Suspension "hypokinesia/hypodynamia" may decrease bone mass by stimulating osteoclast production in ovariectomized mice

This study was conducted to examine, in detail, the histological changes in the femurs of suspended ovariectomized (OVX) mice to assess the role of mechanical stress on bone remodeling. Suspended-OVX, suspended-sham-ope, nonsuspended-OVX, and nonsuspended-sham-operated mice underwent operations 8 weeks after birth. Immediately after operation, hypokinesia/hypodynamia was created by a suspension harness for one week. Five specimens in each group were sacrificed 9 weeks after birth. The trabecular bone of the femurs in the suspended-OVX mice was removed and replaced extensively by bone marrow. The number of tartrate-resistant acid phosphatase (TRAP)-positive cells was larger in the suspended-OVX mice than in the remaining three groups. No significant differences in the number of TRAP positive cells were found between the suspended-sham-ope, nonsuspended-OVX and nonsuspended-sham-ope mice. The femurs of the OVX mouse with suspension "hypokinesia/hypodynamia" thus exhibits extensive trabecular bone loss in association with an increase of osteoclasts.

Regulation of survival and death of mesangial cells by extracellular matrix

BACKGROUND

Cell-matrix interactions exert major effects on such phenotypic features as cell growth and differentiation. Apoptosis is an active form of cell death that is crucial for maintaining the appropriate number of cells as well as the organization of tissue. Recently, it has been suggested that apoptosis of the mesangial cells (MC) is important in glomerular remodeling after injury. The MC are surrounded by an extracellular matrix (ECM) in vivo. Since in disease conditions the mesangial matrix is altered quantitatively and qualitatively, it is of interest to determine whether cell-matrix interactions may influence apoptosis of the MC.

METHODS

We first investigated the differences in the susceptibility to apoptotic stimuli of the MC cultured on various ECM components (type I collagen, fibronectin, basement membrane matrix). We then determined whether the inhibition of MC-matrix interactions would affect apoptosis. Finally, interactions between MC and matrix were disrupted by the inhibition of beta1-integrin expression with antisense oligonucleotides (ODN).

RESULTS

When MC were cultured on type I collagen or fibronectin and deprived of serum for eight hours, the extracted DNA from the MC demonstrated an internucleosomal ladder pattern on gel electrophoresis that constituted the biochemical characteristic of apoptosis. However, no ladder pattern was apparent when MC were cultured on basement membrane matrix. The attachment of cells was completely inhibited when the MC were cultured on agarose-coated dishes for 24 hours. Gel electrophoresis of DNA extracted from these cells showed a ladder pattern. However, the MC attached to the substratum did not show any apoptosis. MC showed an increase in apoptotic cell death after treatment with antisense ODN against beta1-integrin molecule.

CONCLUSIONS

These results indicate that normal ECM may prevent the MC from undergoing apoptosis and serve as a survival factor for MC. Signals from ECM that prevent apoptosis may be mediated by beta1-integrin molecules.

Novel members of the Vesl/Homer family of PDZ proteins that bind metabotropic glutamate receptors

Vesl-1S (186 amino acids, also called Homer) is a protein containing EVH1- and PDZ-like domains whose expression in the hippocampus is regulated during long term potentiation (LTP), one form of synaptic plasticity thought to underlie memory formation (Kato, A., Ozawa, F., Saitoh, Y., Hirai, K., and Inokuchi, K. (1997) FEBS Lett. 412, 183-189; Brakeman, P. R., Lanahan, A. A., O'Brien, R., Roche, K., Barnes, C. A., Huganir, R. L., and Worley, P. F. (1997) Nature 386, 284-288). Here we report additional members of the Vesl/Homer family of proteins, Vesl-1L and Vesl-2. Vesl-1L (366 amino acids), a splicing variant of Vesl-1S, shares N-terminal 175 amino acids with Vesl-1S and contains additional amino acids at the C terminus. Vesl-2 (354 amino acids) was highly related to Vesl-1L in that both contain EVH1- and PDZ-like domains at the N terminus (86% conservation) and an MCC (mutated in colorectal cancer)-like domain and a leucine zipper at the C terminus. In contrast to vesl-1S, we observed no changes in the levels of vesl-1L and vesl-2 mRNAs during dentate gyrus LTP. All these proteins interacted with metabotropic glutamate receptors (mGluR1 and mGluR5) as well as several hippocampal proteins in vitro. Vesl-1L and Vesl-2, but not Vesl-1S, interacted with each other through the C-terminal portion that was absent in Vesl-1S. Vesl-1L and Vesl-2 may mediate clustering of mGluRs at synaptic junctions. We propose that Vesl-1S may be involved in the structural changes that occur at metabotropic glutamatergic synapses during the maintenance phase of LTP by modulating the redistribution of synaptic components.

Structural studies of a stable parallel-stranded DNA duplex incorporating isoguanine:cytosine and isocytosine:guanine basepairs by nuclear magnetic resonance spectroscopy

Isoguanine (2-hydroxyladenine) is a product of oxidative damage to DNA and has been shown to cause mutation. It is also a potent inducer of parallel-stranded DNA duplex structure. The structure of the parallel-stranded DNA duplex (PS-duplex) 5'-d(TiGiCAiCiGiGAiCT) + 5'-d(ACGTGCCTGA), containing the isoguanine (iG) and 5-methyl-isocytosine (iC) bases, has been determined by NMR refinement. All imino protons associated with the iG:C, G:iC, and A:T (except the two terminal A:T) basepairs are observed at 2 degrees C, consistent with the formation of a stable duplex suggested by the earlier Tm measurements [Sugiyama, H., S. Ikeda, and I. Saito. 1996. J. Am. Chem. Soc. 118:9994-9995]. All basepairs are in the reverse Watson-Crick configuration. The structural characteristics of the refined PS-duplex are different from those of B-DNA. The PS duplex has two grooves with similar width (7.0 A) and depth (7.7 A), in contrast to the two distinct grooves (major groove width 11.7 A, depth 8.5 A, and minor groove width 5.7 A, depth 7.5 A) of B-DNA. The resonances of the amino protons of iG and C are clearly resolved and observable, but those of the G and iC are very broad and difficult to observe. Several intercalators with different complexities, including ethidium, daunorubicin, and nogalamycin, have been used to probe the flexibility of the backbone of the (iG, iC)-containing PS-duplex. All of them produce drug-induced UV/vis spectra identical to their respective spectra when bound to B-DNA, suggesting that those drugs bind to the (iG, iC)-containing PS-duplex using similar intercalation processes. The results may be useful in the design of intercalator-conjugated oligonucleotides for antisense applications. The study presented in this paper augments our understanding of a growing number of parallel-stranded DNA structures, including the G-quartet, the i-motif, and the unusual homo basepaired parallel-stranded double helix. Their possible relevance is discussed.

Molecular mechanism of GG-specific photooxidation of DNA

Oxidative DNA damage has been implicated in a variety of pathophysiological processes especially cancer and aging. Therefore, considerable interest has recently been given to the chemical structure and repair mechanisms of the damaged sites. In examining types of novel oxidative DNA damage, our group recently found that 2-aminoimidazolone (Iz) is formed in amounts larger than that of 8-oxo-G during the photoreaction of DNA with riboflavin. Our group also pointed out the intriguing possibility that the Iz thus formed can produce a stable base pair with C, thereby giving rise to a G:C to C:G transversion mutation. In this short review, we focused on the new type of oxidative DNA damage, Iz.

Responses of plasma norepinephrine and heart rate during exercise in patients after Fontan operation and patients with residual right ventricular outflow tract obstruction after definitive reconstruction

To determine the exercise responses of patients with congenital heart disease, 20 patients-5 who had undergone a right ventricular outflow tract reconstruction (group R; age, 15 +/- 2 years), eight who had undergone a Fontan operation (group F; age, 13 +/- 2 years), and seven who had a history of Kawasaki disease (group C; age, 15 +/- 1 years)-performed a treadmill exercise test. Patients of group R had a significant residual right ventricular outflow obstruction. Oxygen uptake (VO2), heart rate (HR), and plasma norepinephrine (NE) concentrations were measured at rest, during warm-up, at ventilatory threshold (VT), and at peak exercise. Exercise capacity was determined as a percentage of the predicted normal peak VO2 (%pVO2). The %pVO2 for groups R and F was 65 +/- 10 and 56 +/- 11, respectively. Peak HR for groups R and F was 171 +/- 4 and 155 +/- 5, which were lower than the HR for group C (p < 0.001). Although NE concentrations at rest, during warm-up, and at VT were significantly greater in groups R and F (p < 0.05), there were no significant differences in the NE concentrations at peak exercise. Peak HR correlated with %pVO2 (p < 0.001). The ratio of the increase in HR to NE from rest to VT was significantly lower in groups R and F than in group C (p < 0.001) and correlated with %pVO2 (r = 0.80; p < 0. 001). These data suggest that sympathetic nervous activity in groups R and F is increased at rest and during mild to moderate exercises, and reduced sinus node sensitivity to NE may be partly responsible for the abnormal HR response during exercise of patients with uncorrected congenital heart disease.

Evidence of Trolox and some gallates as synergistic protectors of erythrocytes against peroxyl radicals

The peroxidation of human erythrocytes induced by peroxyl radical initiator and its inhibition by several gallate esters (e.g., propyl, methyl, ethyl) and Trolox (a more polar analogue of vitamin E) have been studied. The antioxidant activity was determined on erythrocytes against hemolysis generated by a thermal activator, 2,2prime-azobis-(2-amidinopropane)dihydrogenchloride. It was found that propyl gallate and its two analogues were more effective than Trolox in preventing cell lysis. However, the combination of gallate esters and Trolox produced a protective effect exceeding the arithmetic sum of their individual contributions. These perceived synergisms occur at more than one level of Trolox at a given level of a gallate ester.Key words: Trolox, gallates, synergism, peroxyl radicals.

Amino-terminal region of SecA is involved in the function of SecG for protein translocation into Escherichia coli membrane vesicles

Protein translocation across the cytoplasmic membrane of Escherichia coli is accomplished by concerted actions of the translocation ATPase SecA and the membrane-embedded SecE/Y/G complex. SecA interacts with preproteins and undergoes ATP-driven cycles of membrane insertion-deinsertion. To address how SecA interacts functionally with other components in the translocation machinery, we characterized a SecA mutant lacking amino-terminal 8 amino acid residues (SecA N-8). Although the absence of the 8 residues did not grossly affect the interaction of SecA with a preprotein, ATP, or phospholipids, nor did it affect the intrinsic ATPase activity, it gave differential effects on the translocation of different preproteins. It also affected the translocation ATPase activity, the ability of membrane insertion, and the topology inversion of SecG coupled with the membrane insertion-deinsertion of SecA. Most noteworthy, SecA N-8 was pronouncedly defective in the translocation of proton motive force-dependent preproteins, in which SecG might have a role. We propose that the amino-terminal region of SecA is important for the functional interaction with SecG.

Cdc2-cyclin B phosphorylates p70 S6 kinase on Ser411 at mitosis

The carboxyl terminus of p70 S6 kinase (p70(s6k)) has a set of Ser and Thr residues (Ser411, Ser418, Ser424, and Thr421) phosphorylated in vivo by an unidentified kinase(s). These Ser/Thr sites are immediately followed by proline, a motif that is commonly seen in the substrates of cyclin-dependent kinases (Cdk) and mitogen-activated protein kinases. A previous study has shown that Cdc2 (Cdk1) indeed phosphorylates these p70(s6k) Ser/Thr residues in vitro. Here, we demonstrate that Cdc2-cyclin B complex phosphorylates Ser411 in the KIRSPRR sequence, whereas other Cdk-cyclin complexes including those containing Cdk2, Cdk4, or Cdk6 do not. Additionally, Ser411 phosphorylation in vivo was increased at mitosis in parallel with Cdc2 activation, and it was suppressed by a dominant negative form of Cdc2. These data indicate that p70(s6k) is a physiological substrate of Cdc2-cyclin B in mitosis. Since the activity of p70(s6k) is low during mitosis, Cdc2-cyclin B may play a role in inactivating p70(s6k) during mitosis, where protein synthesis is suppressed.

Inhibition of mesangial cell proliferation by E2F decoy oligodeoxynucleotide in vitro and in vivo

The transcription factor E2F coordinately activates several cell cycle-regulatory genes. We attempted to inhibit the proliferation of mesangial cells in vitro and in vivo by inhibiting E2F activity using a 25-bp decoy oligodeoxynucleotide that contained consensus E2F binding site sequence (E2F-decoy) as a competitive inhibitor. The decoy's effect on human mesangial cell proliferation was evaluated by [3H]thymidine incorporation. The E2F decoy inhibited proliferation in a concentration-dependent manner, whereas a mismatch control oligodeoxynucleotide had little effect. Electrophoretic mobility shift assays demonstrated that the decoy's inhibitory effect was due to the binding of the decoy oligodeoxynucleotide to E2F. The effect of the E2F decoy was then tested in a rat anti-Thy 1.1 glomerulonephritis model. The E2F decoy oligodeoxynucleotide was introduced into the left kidney 36 h after the induction of glomerulonephritis. The administration of E2F decoy suppressed the proliferation of mesangial cells by 71%. Furthermore, treatment with the E2F decoy inhibited the glomerular expression of proliferating cell nuclear antigen at the protein level as well as the mRNA level. These findings indicate that decoy oligonucleotides can suppress the activity of the transcription factor E2F, and may thus have a potential in treating glomerulonephritis.

Wilms tumor gene (WT1) as a new marker for the detection of minimal residual disease in leukemia

WT1 (Wilms tumor gene) expression is a new tumor marker of leukemic blast cells of AML, ALL, and CML. Minimal residual disease (MRD) of leukemia can be detected at frequencies as low as 1 in 10(3) to 10(4) normal bone marrow (BM) cells and 1 in 10(5) normal peripheral blood (PB) cells by means of the quantitation of expression levels of the WT1 gene using reverse transcriptase-polymerase chain reaction (RT-PCR). This is regardless of the types of leukemia or the presence or absence of tumor-specific DNA markers. Thus, the WT1 assay makes it possible to rapidly assess the effectiveness of treatment and to evaluate the degree of eradication of leukemic cells in individual leukemia patients. Moreover, molecular relapse using PCR can be diagnosed by the monitoring of WT1 expression levels in BM or PB 1-24 months (means, 7 months for BM and 8 months for PB) before the clinical relapse became apparent. In case of rapid or gradual increase in WT1 expression levels to or over 10(-2) after return to normal BM levels during CR; or retention of the WTI expression at levels near or over 10(-2) in BM without return to normal BM levels even in CR (WT1 expression level in K562 cells was defined as 1.0), it seems that clinical relapse is impending. Since WT1 antisense oligomers inhibit the growth of leukemic cells, it is apparent that the WT1 gene plays an important role in leukemogenesis.

Structure of DNA containing aristeromycin analog

The melting temperatures and thermodynamic properties of several oligodeoxynucleotide duplexes containing one modified deoxyadenosine residue (carbocyclic deoxyadenosine, dAr) were investigated. It was found that the introduction of carbocyclic deoxyadenosine slightly destabilized oligonucleotide duplexes mainly due to an entropic contribution.

Photoreaction of 5-halouracil-containing Z-form DNA

Photoreactions of IU-containing Z-form DNA were investigated. By introducing 8-methylguanine, stable Z-form IU-containing oligonucleotides were prepared. DNA conformational change from B to Z leads to the remarkable acceleration of the photoreactivity of IU-containing oligonucleotides. In particular 2'-hydrogen abstraction was observed preferentially in Z-form DNA, and 2'-hydroxylation occurred specifically at the 5' side of IU in Z-form DNA.

Analysis of guanine oxidation product via electron transfer in 5'-d(TTGGTA)-3'

The photoirradiation of 5'-TTGGTA-3' in the presence of riboflavin with or without complementary oligomer 5'-ATACCAAA-3' was investigated by HPLC analysis. It was found that 2-aminoimidazol-4-one (Iz) containing hexamers, 5'-TTIzGTA-3' and 5'-TTGIzTA-3', were the major products.

Modulation of glutamate sensitivities by inhibitors of a protein kinase and a protein phosphatase in cultured rat Purkinje cells

We examined the effects of inhibitors of calcium-calmodulin-dependent protein kinase II (CaM kinase II) and protein phosphatases on the glutamate (Glu) responses in cultured rat cerebellar Purkinje cells. CaM kinase II inhibitors significantly potentiated Glu responses, and activation of metabotropic Glu receptors facilitated this potentiation. In contrast, a phosphatase inhibitor calyculin A significantly reduced Glu responses. It was suggested that the Glu responsiveness of Purkinje cells may be regulated by the dynamic balance of phosphorylation and dephosphorylation of receptors or other relevant factors under basal conditions.

A practically zero horizontal magnetic field in a planar undulator used in the Tristan Super Light Facility

The Tristan Main Ring (MR) at KEK (High Energy Accelerator Research Organization) has been used as a third-generation synchrotron radiation ring with an undulator installed in the MR as a third-generation light source. The magnetic field irregularities of the undulator were examined precisely. Measurement of the magnetic field after synchrotron radiation experiments showed that the magnetic irregularities in both the horizontal and vertical directions are negligibly small. This result suggests that our previous estimates of emittance, made using the measured undulator spectrum, should correctly represent the properties of the electron beam in the MR.

High-Resolution X-ray Diffraction of Muscle Using Undulator Radiation from the Tristan Main Ring at KEK

High Energy Accelerator Research Organization (KEK), Tsukuba, Japan.High-resolution X-ray diffraction studies on striated muscle fibres were performed using a hard X-ray undulator installed in the Tristan main ring at KEK, Tsukuba, Japan. The performance of the undulator, along with an example experiment which exploited the unique characteristics of undulator radiation, are reported. The vertical divergence angle of the first harmonic of the undulator was approximately 10 micro rad under 8 GeV multi-bunch operating conditions and the peak photon flux density was estimated to be approximately 3 x 10(16) photons s(-1) mrad(-2) (0.1% bandwidth)(-1) (10 mA)(-1). The well collimated X-ray beam from the undulator made it possible to resolve clearly, with high angular resolution ( approximately 700 nm), the closely spaced diffraction peaks on the meridional axis in the X-ray patterns arising from the thick filaments of a striated muscle under static conditions. By fitting the meridional intensity pattern, a model for the molecular arrangement of the constituent proteins in the thick filaments is proposed. These studies of muscle demonstrate the promise of undulator radiation from third-generation sources for high-resolution diffraction studies.

Characterization of windows and filters for coherent X-ray beamlines

Beryllium windows and graphite heat absorbers used in coherent X-ray beamlines must be optically flat. If the optical path through the window varies by more than lambda/4, the X-ray wave front will be distorted after passing through the window, and the divergence of the X-ray beam may be increased. This reduces the beam coherence. Beryllium, graphite and Kapton films have been tested using ultra-small-angle X-ray scattering. Wave-front distortion was also directly observed by means of phase-contrast X-ray microradiography. The measured increase of angular divergence is about 4 micro rad. The wave-front distortion is larger than 2pi (optical path difference of lambda). These are serious problems for utilizing coherent X-ray beams.

Wilms' tumor gene (WT1) competes with differentiation-inducing signal in hematopoietic progenitor cells

The WT1 gene is a tumor-suppressor gene that was isolated as a gene responsible for Wilms' tumor, a childhood kidney neoplasm. We have previously reported that the WT1 gene is strongly expressed in leukemia cells with an increase in its expression levels at relapse and an inverse correlation between its expression levels and prognosis, thus making it a novel tumor marker for leukemic blast cells. Furthermore, WT1 antisense oligomers have been found to inhibit the growth of leukemic cells. These results strongly suggested the involvement of the WT1 gene in human leukemogenesis. The present study was performed to prove our hypothesis that the WT1 gene plays a key role in leukemogenesis and performs an oncogenic function in hematopoietic progenitor cells, rather than a tumor-suppressor gene function. 32D cl3, an interleukin-3-dependent myeloid progenitor cell line, differentiates into mature neutrophils in response to granulocyte colony-stimulating factor (G-CSF). However, when transfected wild-type WT1 gene was constitutively expressed in 32D cl3, the cells stopped differentiating and continued to proliferate in response to G-CSF. As for signal transduction mediated by G-CSF receptor (G-CSFR), Stat3alpha was constitutively activated in wild-type WT1-infected 32D cl3 in response to G-CSF, whereas, in WT1-uninfected 32D cl3, activation of Stat3alpha was only transient. However, most interesting was the fact that G-CSF stimulation resulted in constitutive activation of Stat3beta only in wild-type WT1-infected 32D cl3, but not in WT1-uninfected 32D cl3. Thus, WT1 expression constitutively activated both Stat3alpha and Stat3beta. A transient activation of Stat1 was detected in both wild-type WT1-infected and uninfected 32D cl3 after G-CSF stimulation, but no difference in its activation was found. No activation of MAP kinase was detected in both wild-type WT1-infected and uninfected 32D cl3 after G-CSF stimulation. These results demonstrated that WT1 expression competed with the differentiation-inducing signal mediated by G-CSFR and constitutively activated Stat3, resulting in the blocking of differentiation and subsequent proliferation. Therefore, the data presented here support our hypothesis that the WT1 gene plays an essential role in leukemogenesis and performs an oncogenic function in hematopoietic progenitor cells and represent the first demonstration of an important role of the WT1 gene in signal transduction in hematopoietic progenitor cells.