Suppression of cell proliferation and deoxyribonucleic acid synthesis in the cloned rat hepatoma H4-II-E cells overexpressing regucalcin

The role of endogenous regucalcin (RC) in the regulation of cell proliferation was investigated in the cloned rat hepatoma H4-II-E cells overexpressing RC stably. H4-II-E cells were transfected with RC/pCXN2 vector and the multiple neomycin-resistant clones which overexpress stably RC were selected. The RC content of RC/pCXN2-transfected cells used in this study was 19.7-fold as compared with that of the parental wild type H4-II-E cells. Wild type H4-II-E cells, pCXN2 vector-transfected cells (mock type), and RC/pCXN2-transfected cells (transfectants) were cultured for 24, 48, and 72 h in the presence of fetal bovine serum (10% FBS). Cell numbers of wild and mock type were significantly increased with the time course of culture. Cell numbers of transfectants was significantly suppressed as compared with that of wild and mock type. Deoxyribonucleic acid (DNA) synthesis activity in the nuclear fraction of H4-II-E cells was significantly suppressed in transfectants with culture for 12-48 h. The presence of anti-RC monoclonal antibody (10-50 ng/ml) in the reaction mixture caused a significant increase in DNA synthesis activity in the nuclei of wild type and transfectants; this increase was remarkable in transfectants. The effect of anti-RC monoclonal antibody (50 ng/ml) in increasing DNA synthesis activity in transfectants was completely prevented by the addition of regucalcin (1 microM). This study demonstrates that cell proliferation is suppressed in the cloned rat hepatoma H4-II-E overexpressing RC stably.

O(2) delivery and the venous P(O(2))-O(2) uptake relationship in pump-perfused canine muscle

Under the conditions of both an increased red cell affinity for O(2) at a constant rate of O(2) delivery (arterial O(2) content x flow) and a decrease in the rate of O(2) delivery induced by hypoxic hypoxia at constant blood flow, we have obtained a linear relationship between the partial pressure of O(2) in the muscle venous effluent (P(v,)(O(2))) and O(2) uptake (.V(O(2))). The relationship is described by the equation .V(O(2)) = D(a) x P(v,)(O(2)) + .V(O(2)conv)) where D(a) is the apparent O(2) diffusion capacity and .V(O(2)conv)) is O(2) delivery-limited .V(O(2)), and D(a) x P(v,)(O(2)) represents the O(2) diffusion-limited .V(O(2)) .V(O(2)diff)). From these observations, we propose the hypothesis that .V(O(2)) consists of two additive values, .V(O(2)conv)) and .V(O(2)diff)). The mechanism underlying the reduction in .V(O(2)) that is induced by reducing O(2) delivery to markedly below the .V(O(2)conv)) value has only been investigated using a model based on the single compartment of diffusion-limited .V(O(2)), and has not been investigated in terms of this additive .V(O(2)) model. The single compartment analysis appears to overestimate the role of O(2) diffusion in limiting the reduction of .V(O(2)) that occurs in response to a decrease in O(2) diffusion capacity, as reflected by the .V(O(2))/P(v,)(O(2)) ratio. To gain better insight into the mechanism involved, we altered the rate of O(2) delivery by changing arterial P(O(2)) from normoxia (with inhalation of air) to hypoxia (by inhalation of 10-11 % O(2)) and blood flow (with high and low flow rates (n = 7 for both groups), and very low and ischaemic flow rates (n = 4 for both groups)) in pump-perfused dog gastrocnemius preparations during tetanic isometric contractions at 1 Hz. As rates of O(2) delivery were reduced from 23.2 to 10.9 ml min(-1) (100 g)(-1), significant decreases in P(v,)(O(2)) and .V(O(2)) were observed (P < 0.05). From the data of P(v,)(O(2)) and .V(O(2)) values within this range of O(2) delivery rates, we obtained the regression equation .V(O(2)) = 0.22 x P(v,)(O(2)) + 8.14 (r = 0.58). From the equation, the intercept of the .V(O(2))-axis was significantly different from zero (P < 0.05), in accordance with the observation that the .V(O(2)) /P(v,)(O(2)) ratio (ml min(-1) (100 g)(-1) Torr(-1)) increased from 0.54 to 1.35 (P < 0.05). However, at extremely low rates of O(2) delivery (5.6 and 7.3 ml min(-1) (100 g)(-1) the .V(O(2))/P(v,)(O(2)) ratio was 1.51 and 2.80 (P < 0.05), respectively. This indicates a break in the linear .V(O(2))-P(v,)(O(2)) relationship as the rate of O(2) delivery was reduced to below the .V(O(2)conv)) value of the .V(O(2))-axis intercept. These results suggest that the reduction in .V(O(2)) caused by extreme reductions in the rate of O(2) delivery is not attributable to a reduction in O(2) diffusion capacity, as expected from the .V(O(2))/P(v,)(O(2)) ratio, but to a reduction in the O(2) delivery-limited .V(O(2)) component, as evaluated by the .V(O(2))-axis intercept of the linear .V(O(2))-P(v,)(O(2)) relationship.

Stimulatory effect of zinc on insulin-like growth factor-I and transforming growth factor-beta1 production with bone growth of newborn rats

The effect of zinc, an essential trace element, on insulin-like growth factor-I (IGF-I) and transforming growth factor-beta1 production was investigated to determine the role of this metal in bone growth of newborn rats. Femoral-diaphyseal and metaphyseal tissues were obtained between 1 and 28 days after birth of newborn rats, and cultured for 24 h in a serum-free Dulbecco's modified Eagle's medium containing either vehicle or zinc sulfate (10(-6) - 10(-4) M). Protein concentration in the medium was significantly increased by culture with bone tissues of newborn rats with increasing age (14 and 21 days). Medium IGF-I and TGF-beta1 concentration was gradually reduced with increasing age after birth. The presence of zinc (10(-5) and 10(-4) M) caused a significant increase in protein, IGF-I, and TGF-beta1 concentrations in the medium cultured with the diaphyseal or metaphyseal tissues obtained at 7 and 14 days after birth. The expression of IGF-I and TGF-beta1 mRNA was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis in the diaphyseal and metaphyseal tissues cultured for 24 h using rat IGF-I or TGF-beta1-specific primers. These expressions were significantly raised in the presence of zinc (10(-4) M) in culture medium. The present study demonstrates that zinc has a stimulatory effect on IGF-I and TGF-beta1 production in the femoral tissues with bone growth of newborn rats.

An evaluation of screening for lung cancer in Niigata Prefecture, Japan: a population-based case-control study

Although an annual screening programme for lung cancer has been carried out widely in Japan since 1987, there is insufficient evidence to confirm its efficacy in terms of reducing mortality. In order to evaluate the efficacy of the lung cancer screening which has been widely carried out in Japan since 1987, a case-control study was conducted in Niigata Prefecture, Japan. In the study area, chest X-ray examinations for all participants and sputum cytology for high-risk participants were offered annually. Case subjects, who had died from lung cancer (174), and control subjects matched by sex, year of birth, residence and smoking status (801), who had been alive at the time of diagnosis of the corresponding case, were selected from the National Health Insurance holders. Screening histories of the subjects were compared between cases and matched controls for the identical calendar period before the time of diagnosis of the cases. The odds ratio of death from lung cancer for those screened within 12 months vs those not screened was 0.401 (95% CI: 0.272-0.591) with adjustment by smoking index. Our results suggest that annual lung cancer screening might reduce mortality from lung cancer by approximately 60%.

Molecular cloning and sequencing of the cDNA coding for a novel regucalcin gene promoter region-related protein in rat, mouse and human liver

The molecular cloning and sequencing of the cDNA coding for a novel regucalcin gene promoter region-related protein (RGPR) was investigated using rat, mouse and human liver cDNA library with a yeast one-hybrid system and a rapid amplification of cDNA ends (RACE) method. The clone coding an unknown protein was isolated, and a novel protein was identified. This protein was termed as RGPR-p117. RGPR-p117 in rat, mouse and human liver consisted of 1058, 1051 and 1060 amino acid residues with calculated molecular mass of 117, 115 and 117 kDa and estimated pI of 5.69, 5.70 and 5.71, respectively. The homologies of amino acids among rat, mouse and human RGPR-p117 were at least 70%. RGPR-p117 had a leucine zipper motif. The expression of RGPR-p117 mRNA was found in the liver, kidney, heart, spleen, and brain of rats. The database search of the human RGPR-p117 showed that its gene consisted of at least 26 exons spanning approximately 4.1 kbp and localized on human chromosome 1q25.2. Furthermore, we found a cDNA clone which was highly identical to a front half part of the human RGPR-p117 cDNA, using the BLAST search of human RGPR-p117. This cDNA clone was a splicing variant of human RGPR-p117, which derived from human placental choriocarcinoma. Our study demonstrates that a novel gene coding RGPR-p117 is present in rat, mouse and human.

Clarithromycin resistance, but not CYP2C-19 polymorphism, has a major impact on treatment success in 7-day treatment regimen for cure of H. pylori infection: a multiple logistic regression analysis

Mutations in the gene encoding the CYP2C-19 enzyme for PPI metabolism have been shown to enhance the chance for a cure in a H. pylori-positive patients using a two-week dual-therapy regimen involving omeprazole and amoxicillin. However, the impact of CYP2C-19 genetic polymorphism on eradication rates of a one-week triple-therapy regimen has not been examined. In this cohort study, 156 H. pylori-positive peptic ulcer or NUD patients who presented to our university hospital were recruited. They were treated by one-week omeprazole-amoxicillin-clarithromycin therapy. Host and bacterial predictive factors including H. pylori susceptibility and CYP2C-19 genotyping, as well as cure rate for H. pylori infection, were studied. Cure rate was 85.9% (95% CI: 79-91%) on an intent to treat (ITT) basis. By multiple logistic regression analysis, only clarithromycin resistance had a significant impact on treatment success (odds ratio 28.7: 95% CI: 6-172). CYP2C-19 genetic polymorphism was not associated with a significant change in cure rate. These observations indicate only clarithromycin susceptibility, not CYP2C-19 polymorphism, has a major impact on the treatment success when using a seven-day OAC H. pylori treatment regimen.

Involvement of nuclear factor-1 (NF1) binding motif in the regucalcin gene expression of rat kidney cortex: the expression is suppressed by cisplatin administration

The binding of nuclear factor on the promoter region of the regucalcin gene and the expression of regucalcin in the kidney cortex of rats was investigated. Nuclear extracts from kidney cortex were used for oligonucleotide competition gel mobility shift assay. An oligonucleotide between position -523 and -506 in the 5'-flanking region of the rat regucalcin gene, which contains a nuclear factor 1 (NF1) consensus motif TTGGC(N)6CC, competed with the probe for the binding of the nuclear protein from kidney cortex. The mutation of TTGGC in the consensus sequence caused an inhibition of the binding of nuclear factors. The binding of nuclear factor on the 5'-flanking region was clearly reduced in the kidney cortex obtained at 1, 2, and 3 days after a single intraperitoneal administration of cisplatin (1.0 mg/100 g body wt) to rats. Moreover, cisplatin administration caused a remarkable decrease in regucalcin mRNA levels and regucalcin concentration in the kidney cortex. Also, serum regucalcin concentration was significantly decreased by cisplatin administration. Meanwhile, serum urea nitrogen concentration was markedly elevated by cisplatin administration. The present study demonstrates that the specific nuclear factor binds to the NF1-like sequence in the promotor region of regucalcin gene in the kidney cortex of rats, and that the nuclear factor binding and regucalcin expression are suppressed by cisplatin administration.

Distribution of the high-affinity choline transporter in the central nervous system of the rat

In cholinergic nerve terminals, Na(+)- and Cl(-)-dependent, hemicholinium-3-sensitive, high-affinity choline uptake is thought to be the rate-limiting step in acetylcholine synthesis. The high-affinity choline transporter cDNA responsible for the activity was recently cloned. Here we report production of a highly specific antibody to the high-affinity choline transporter and distribution of the protein in the CNS of the rat. The antibody stained almost all known cholinergic neurons and their terminal fields. High-affinity choline transporter-immunoreactive cell bodies were demonstrated in the olfactory tubercle, basal forebrain complex, striatum, mesopontine complex, medial habenula, cranial nerve motor nuclei, and ventral horn and intermediate zone of the spinal cord. Noticeably, high densities of high-affinity choline transporter-positive axonal fibers and puncta were encountered in many brain regions such as cerebral cortex, hippocampus, amygdala, striatum, several thalamic nuclei, and brainstem. Transection of the hypoglossal nerve resulted in a loss of high-affinity choline transporter immunoreactivity in neurons within the ipsilateral hypoglossal motor nucleus, which paralleled a loss of immunoreactivity to choline acetyltransferase. The antibody also stained brain sections from human and mouse, suggesting cross-reactivity. These results confirm that the high-affinity choline transporter is uniquely expressed in cholinergic neurons and is efficiently transported to axon terminals. The antibody will be useful to investigate possible changes in cholinergic cell bodies and axon terminals in human and rodents under various pathological conditions.

Sustained high O2 use for Ca2+ handling in rat ventricular slices under decreased free shortening after ryanodine

We hypothesized that O2 wasting of Ca2+ handling in the excitation-contraction coupling in ryanodine-treated failing hearts might derive from an increased external Ca2+ extrusion via Na+/Ca2+ exchanger and futile Ca2+ cycling via sarcoplasmic reticulum (SR) Ca2+-ATPase. We tested this hypothesis by mechanoenergetic studies using rat left ventricular slices. After the slices were treated with ryanodine (0.1 microM), 1-Hz free shortening significantly decreased by 78-85%, whereas the observed O2 consumption (VO2) required for total Ca2+ handling, increased from 0.79 to 1.13 ml O2 x min(-1) x 100 g x LV(-1) (155.6% of control). We reconfirmed that cyclopiazonic acid (10 microM), a blocker of SR Ca2+-ATPase, decreased VO2 by 75-80% in normal slices. However, 100 microM of cyclopiazonic acid was needed to inhibit the VO2 by 80% after ryanodine treatment. Blockade of a sarcolemmal Na+/Ca2+ exchanger by KB-R7943 (10 microM) significantly decreased VO2 by 45% after ryanodine treatment without significant effects on normal slices. Our results indicated that the VO2 increase following ryanodine treatment was derived from a net change of an increased external Ca2+ extrusion via Na+/Ca2+ exchanger and futile Ca2+ cycling via SR Ca2+-ATPase.

Glucose sensing based on interdigitated array microelectrode

A micro glucose sensor consisting of an interdigitated array gold microelectrode was developed. The interdigitated array structure, which has 10 microns band width and 10 microns band gap, was fabricated in a small region (2.5 x 5 mm2) on a quartz substrate. Glucose oxidase was chemically fixed onto the electrode surface through self-assembled monolayer of 11-mercaptoundecanoic acid; ferroceneacetic acid was used as electron mediator. Electrochemical properties of the glucose oxidase-immobilized microelectrode were investigated by cyclic voltammogram measurements. Results confirmed that the reductive ferroceneacetic acid generated at counter electrode diffuses through a narrow band gap (10 microns) and can reach the working electrode surface.

Cellular mRNA expression of the transcription factor NGFI-B suggests a gene regulatory role in striatal opiate-peptide neurons

Previous studies have shown that NGFI-B mRNA is highly expressed in the adult striatum. In the present study we analyzed the anatomical distribution of NGFI-B mRNA within this brain region as well as the degree of co-existence of NGFI-B with different striatal markers in the adult brain. NGFI-B mRNA levels were found to be significantly higher within the dorsomedial portion of the striatum as compared to the ventrolateral striatum. This distribution pattern was maintained throughout the rostro--caudal axis of the striatum. Double in situ hybridization studies showed that striatal NGFI-B mRNA colocalized with a subset of preproenkephalin and prodynorphin positive spiny neurons within the dorsomedial striatum; 22--28% of all opiate-peptide positive cells co-expressed NGFI-B mRNA. NGFI-B did not colocalize with striatal aspiny interneurons expressing choline acetyl transferase mRNA or those containing the calcium-binding protein parvalbumin. The pattern of NGFI-B mRNA expression within different striatal spiny projecting neurons suggests that this transcription factor may have a direct effect on the function of different striatal efferent pathways.

Circulating transforming growth factor beta 1 as a predictor of liver metastasis after resection in colorectal cancer

Plasma transforming growth factor beta1 (TGF-beta1) has been reported to be correlated with the extent of disease in colorectal cancer, but it is not known whether measuring this cytokine can help predict liver metastasis after curative resection. We prospectively studied whether plasma TGF-beta1 levels could predict liver metastasis in 117 patients with colorectal cancer before and after curative resection. Blood samples were drawn before and 2 weeks after surgery to determine the cytokine levels. Abdominal ultrasonography or computed tomography was done every 3 months after surgery. The primary end point for follow-up was recurrence. Seventy-seven of 117 cases (66%) had preoperative levels of the cytokine higher than the borderline limit of 7.5 ng/ml. Postoperative levels were >7.5 ng/ml in 29 of 117 patients (25%). The median follow-up period was 42 months (range, 5--66 months), with follow-up of all 117 patients. No recurrence was observed in 13 patients with Dukes' stage A lesions. Liver metastasis occurred in 18 of 104 patients (17%) with Dukes' stage B or C disease. Fourteen of 18 patients (78%) who developed liver metastasis had shown a postoperative plasma TGF-beta1 level of >7.5 ng/ml. Cox proportional hazards regression analysis showed that the postoperative level was a significant predictive factor for liver metastasis (P < 0.001). A single point measurement of plasma TGF-beta1 levels at 2 weeks after curative resection seems to be able to predict liver metastasis in colorectal cancer. This finding suggests the value of a prospective trial of liver-targeted adjuvant therapy for patients with elevated postoperative plasma TGF-beta1 levels.

No dependency of a new index for oxygen cost of left ventricular contractility on heart rates in the blood-perfused excised rat heart

We have reported the linear relation of myocardial oxygen consumption per beat (VO(2)) and systolic pressure-volume area (PVA) in the left ventricle of the cross-circulated rat heart. The VO(2) intercept (PVA-independent VO(2)) is primarily composed of VO(2) for Ca(2+) handling in excitation-contraction coupling and basal metabolism. Recently, we proposed a new index for oxygen cost of contractility obtainable as a slope of a linear relation between PVA-independent VO(2) and left ventricular contractility. This index indicates the Ca(2+) handling VO(2) per unit contractility change. However, a dependency of this index on heart rate has not yet been investigated. The aim of the present study was to investigate the dependency of oxygen cost of contractility on heart rate. This is a critical point to compare this cost under different heart rates. At first we found no differences of VO(2)-PVA relations at 240 and 300 beats/min (bpm). Therefore, after control VO(2)-PVA relation at 300 bpm, we gradually enhanced left ventricular contractility by Ca(2+) at a midrange left ventricular volume and obtained the gradually increased PVA-independent VO(2). At each contractility level, the pacing rate was alternately changed at 240 and 300 bpm. We obtained the two composite VO(2)-PVA relation lines and found no significant differences between the slopes of PVA-independent VO(2) and left ventricular contractility relations at 240 and 300 bpm. The present results indicated no dependency of oxygen cost of left ventricular contractility on heart rates within 240--300 bpm. Based on this fact, we concluded that even under the different pacing rates within 240--300 bpm, this oxygen cost is valid for assessing cardiac mechanoenergetics, especially the economy of total Ca(2+) handling in E-C coupling.

Contrasting localizations of MALS/LIN-7 PDZ proteins in brain and molecular compensation in knockout mice

Proteins containing PDZ (postsynaptic density-95, discs large, zonula occludens) domains play a general role in recruiting receptors and enzymes to specific synaptic sites. In Caenorhabditis elegans, a complex of three PDZ proteins, LIN-2/7/10, mediates basolateral targeting of a receptor tyrosine kinase. Homologs of these LIN proteins have also been identified in higher organisms, and here we analyze the MALS/Veli (mammalian LIN-7/vertebrate homolog of LIN-7) proteins in brain. Immunohistochemical staining and in situ hybridization show that MALS occur differentially in discrete populations of neurons throughout the brain. Most neurons express only one MALS protein, although some cells contain two or even all three MALS isoforms. At the subcellular level, MALS proteins are found in both dendritic and axonal locations, suggesting that they may regulate processes at both pre- and postsynaptic sites. Targeted disruption of MALS-1 and MALS-2 does not yield a detectable phenotype, and hippocampal synaptic function and plasticity are intact in the MALS-1/2 double knockouts. Interestingly, MALS-3 protein is dramatically induced in the MALS-1/2 double knockouts, implying that dynamic changes in protein expression may play an important regulatory role for this family of synaptic PDZ proteins.

Arbitrary-lattice photonic crystals created by multiphoton microfabrication

We used voxels of an intensely modified refractive index generated by multiphoton absorption at the focus of femtosecond laser pulses in Ge-doped silica as photonic atoms to build photonic lattices. The voxels were spatially organized in the same way as atoms arrayed in actual crystals, and a Bragg-like diffraction from the photonic atoms was evidenced by a photonic bandgap (PBG) effect. Postfabrication annealing was found to be essential for reducing random scattering and therefore enhancing PBG. This technique has an intrinsic capability of individually addressing single atoms. Therefore the introduction of defect structures was much facilitated, making the technique quite appealing for photonic research and applications.

Femtosecond laser-assisted three-dimensional microfabrication in silica

We demonstrate direct three-dimensional (3-D) microfabrication inside a volume of silica glass. The whole fabrication process was carried out in two steps:(i) writing of the preprogrammed 3-D pattern inside silica glass by focused femtosecond (fs) laser pulses and (ii) etching of the written structure in a 5% aqueous solution of HF acid. This technique allows fabrication of 3-D channels as small as 10mum in diameter inside the volume with any angle of interconnection and a high aspect ratio (10mum -diameter channels in a 100mum -thick silica slab).

Oxygen wasting for Ca2+ extrusion activated by partial inhibition of sarcoplasmic reticulum Ca2+ -atpase by cyclopiazonic acid in rat left ventricles

In the excised Langendorff-perfused rat whole-heart preparation, a linear relation between left ventricular myocardial oxygen consumption per beat (Vo2) and systolic pressure-volume area (PVA, a total mechanical energy per beat) is obtained from a curved end-systolic pressure-volume relation as in the blood-perfused preparation. The ordinate Vo2 intercept of the Vo2-PVA relation is composed of Vo2 for total Ca2+ handling in the excitation-contraction coupling and basal metabolism. The Vo2 for total Ca2+ handling is mainly consumed by sarcoplasmic reticulum (SR) Ca2+ -ATPase. The aim of the present study was to investigate, in terms of left ventricular mechanoenergetics, how an inhibition of SR Ca2+ -ATPase by cyclopiazonic acid (CPA; 4 micromol/l) affects Ca2+ handling mechanisms in the excised Langendorff-perfused rat whole-heart preparation. The short-term (for 3 to 6 min after onset of the infusion) CPA infusion decreased Vo2 proportionally to the decrease in PVA. The long-term (for 9 to 12 min after the short-term CPA infusion) CPA infusion gradually increased Vo2 almost to the control level with an increase in PVA. The increases in both Vo2 and PVA during this infusion were completely abolished by a Na+/Ca2+ exchanger inhibitor, 3'9,4'9-dichlorobenzamil, indicating the contribution of Na+/Ca2+ exchanger to the increases in Vo2 and PVA. The O2 cost of left ventricular contractility during the long-term CPA infusion was significantly higher than during the short-term CPA infusion. All these results suggest the possibility of the contribution of greater energy-wasting Ca2+ extrusion processes (such as Na+/K+-ATPase coupled to the Na+/Ca2+ exchanger; its stoichiometry is 1 ATP : 1 Ca2+ to the larger oxygen cost of left ventricular contractility.

Synthesis of ketonylplatinum(III) dinuclear complexes: observation of the competitive radical vs electrophilic displacement in Pt(III)-promoted C-H bond activation of ketones

New ketonylplatinum(III) dinuclear complexes [Pt(2)((CH(3))(3)CCONH)(2)(NH(3))(4)(CH(2)COPh)](NO(3))(3) (4), [Pt(2)((CH(3))(3)CCONH)(2)(NH(3))(4)(CH(CH(3))COC(2)H(5))](NO(3))(3) (5), and [Pt(2)((CH(3))(3)CCONH)(2)(NH(3))(4)(CH(2)COCH(2)COCH(3))](NO(3))(3) (6) were prepared by treatment of platinum blue complex [Pt(4)(NH(3))(8)((CH(3))(3)CCONH)(4)](NO(3))(5) (2) with acetophenone, 3-pentanone, and acetylacetone, respectively, in the presence of concentrated HNO(3). The structures of complexes 4 and 6 have been confirmed by X-ray diffraction analysis, which revealed that the C-H bonds of the methyl groups in acetophenone and acetylacetone have been cleaved and Pt(III)-C bonds are formed. Formation of diketonylplatinum(III) complex 6 provides a novel example of the C-H bond activation not at the central alpha-C-H but at the terminal methyl of acetylacetone. Reaction with butanone having unsymmetrical alpha-H atoms led to two types of ketonylplatinum(III) complexes [Pt(2)((CH(3))(3)CCONH)(2)(NH(3))(4)(CH(CH(3))COCH(3))](NO(3))(3) (7a) and [Pt(2)((CH(3))(3)CCONH)(2)(NH(3))(4)(CH(2)COCH(2)CH(3))](NO(3))(3) (7b) at a molar ratio of 1.7 to 1 corresponding to the C-H bond activation of methylene and methyl groups, respectively. Use of 3-methyl-2-butanone instead of butanone gave complex [Pt(2)((CH(3))(3)CCONH)(2)(NH(3))(4)(CH(2)COCH(CH(3))(2))](NO(3))(3) (8) as a sole product via C-H bond activation in the alpha-methyl group. The reactivity of the ketonylplatinum(III) dinuclear complexes toward nucleophiles, such as H(2)O and HNEt(2), was examined. The alpha-hydroxyl- and alpha-amino-substituted ketones were generated in the reactions of [Pt(2)((CH(3))(3)CCONH)(2)(NH(3))(4)(CH(2)COCH(3))](NO(3))(3) (1), 5, and a mixture of 7a and 7b with water and amine, which indicates that the carbon atom in the ketonyl group bound to the Pt(III) atom can receive a nucleophilic attack. The high electrophilicity of the ketonylplatinum(III) complexes can be accounted for by the high electron-withdrawing ability of the platinum(III) atom. A competition between the radical and electrophilic displacement pathways was observed directly in the C-H bond activation reaction with butanone giving complexes 7a and 7b. Addition of a radical trapping agent suppressed the radical pathway and gave complex 7b as the predominant product. On the contrary, 7a was formed as the main product when the reaction solution was irradiated by mercury lamp light. These results together with other mechanistic studies demonstrate that complex 7a was produced via a radical process, whereas complex 7b is produced via electrophilic displacement of a proton by the Pt(III) atom. The competitive processes were further observed in the reactions of platinum blue complex 2 with a mixture of acetone and 3-pentanone in the presence of HNO(3). The relative molar ratio of acetonyl complex 1 to pentanoyl complex 5 was 3 to 1 under room light, whereas formation of complex 5 was almost suppressed when the reaction was carried out in the dark with the addition of a radical trapping agent.

Multiple combination-sensitive neurons in the auditory cortex of the mustached bat

The mustached bat, Pteronotus parnellii, emits biosonar pulses consisting of four constant-frequency (CF(1-4)) and four frequency-modulated (FM(1-4)) components. The FM-FM area of its auditory cortex consists of three subdivisions, containing either FM(1)-FM(2), FM(1)-FM(3) or FM(1)-FM(4) combination-sensitive neurons. The FM-FM area also contains 'multiple combination-sensitive' neurons: FM(1)-FM(2,3), FM(1)-FM(3,4), FM(1)-FM(2,4), and FM(1)-FM(2,3,4) neurons. All FM-FM neurons are tuned to a time delay (echo delay) of FM(n) (n=2-4) from FM(1). In the present study, we made the following four major findings. (1) Multiple combination-sensitive neurons show the strongest response to a combination of more than two signal elements. (2) Multiple combination-sensitive neurons are located in about 100 microm wide bands at the boundaries between two adjacent subdivisions of the FM-FM area. (3) Iso-best-delay contour lines across the three single combination-sensitive subdivisions are not interrupted by multiple combination-sensitive bands. (4) Each subdivision of the FM-FM area has frequency-vs.-frequency coordinates in terms of best FM(1) and best FM(n) frequencies for facilitation, although such coordinates were not obtained with single tone bursts.

A novel function of synapsin II in neurotransmitter release

Although synapsin has been localized to presynaptic structures, its function remains poorly understood. In the present study, we investigated the presynaptic function of synapsin II using a synaptic vesicle recycling process using synapsin-II-overexpressing NG108-15 cells. Western blot analysis with antibodies for synaptic-vesicle-associated protein indicated that the number of synaptic vesicles was approximately doubled in synapsin II transfectants as reported previously. In differentiated synapsin-II-overexpressing and control cells, the application of high potassium induced strong intracellular calcium elevation along neurites and varicosities after differentiation and a weak calcium rise in the cell bodies. The uptake and release of the fluorescent dye FM1-43 revealed that synaptic vesicle recycling in synapsin-II-transfected cells occurred with the same kinetics in the cell body and neuritic varicosities. Furthermore, the area labeled with FM1-43 fluorescence in the synapsin-II-transfected cells was approximately twice as much as in control cells after stimulation, and ATP released after synaptic vesicle fusion with the plasma membrane in synapsin-II-expressing cells was significantly elevated relative to controls. The number of synaptic vesicles paralleled the amount of transmitter released from the cells leading to the conclusion that the number of releasable synaptic vesicles were increased by synapsin II transfection into NG108-15 cells, suggesting that synapsin II may have a role in the regulation of synaptic vesicle number in presynapse-like structures in NG108-15 cells.

Intracellular signaling factors--enhanced hepatic nuclear protein binding to TTGGC sequence in the rat regucalcin gene promoter: involvement of protein phosphorylation

The transcriptional mechanism of regucalcin gene expression was determined using gel mobility shift assay with TTGGC oligonucleotide (II-b) which is located between position -523 and -506 in the promoter region, containing a nuclear factor I (NF1) consensus motif TTGGC(N)(6)CC. The mutation analysis in this motif showed that TTGGC sequence was a specific binding region of the nuclear protein in rat liver and the cloned rat hepatoma cells (H4-II-E). When liver nuclei were incubated with ATP (1 mM), the nuclear protein binding to TTGGC sequence was increased. This binding was also increased in the nuclei of H4-II-E cells cultured with 10% FBS. Such an increase was also seen by culture with vanadate (100 microM), a potent inhibitor of protein tyrosine phosphatase. Serum-enhanced nuclear protein binding to TTGGC sequence was decreased in the presence of TFP (10 microM), staurosporine (100 nM), genistein (10 microM), PD98059 (10 microM), or wortmannin (10 nM), which are inhibitors of various protein kinases. Treatment of a monoclonal phosphotyrosine antibody (4G10) caused an alteration in the TTGGC oligonucleotide-nuclear protein complex formation, indicating that tyrosine phosphorylation of nuclear protein is partly involved in the binding to TTGGC sequence. Moreover, when H4-II-E cells were cultured with FBS (10%), Bay K 8644 (5 microM), PMA (1 microM), or insulin (20 nM), the protein binding to TTGGC sequence in the nuclei was increased, while it was reduced in the cytoplasm, indicating a nuclear localization of the TTGGC sequence-binding protein. This study demonstrates that hepatic nuclear protein can specifically bind to the TTGGC sequence in rat regucalcin gene promoter region, and that this binding is enhanced by intracellular signaling factors which are partly mediated through protein phosphorylation.

Very strong correlation between dominant negative activities of mutant thyroid hormone receptors and their binding avidity for corepressor SMRT

The syndrome of resistance to thyroid hormone (RTH) is an inherited disorder involving a mutation of the thyroid hormone receptor (TR) gene. Mutant (m) TR inhibits wild-type (wt) TR functions in a dominant negative manner, and this dominant negative effect (DNE) is a crucial factor in RTH pathogenesis. The molecular mechanism of the DNE is still unclear, although several possibilities (including competition between wt- and mTRs at the T(3) response element (TRE), sequestration of TR-associated protein(s) and titration out of functional TR) have been considered. Here we report that the DNE of mTRs is strongly correlated with their binding avidity for the retinoid X receptor (RXR), and especially for corepressor SMRT (silencing mediator for retinoid and thyroid hormone receptor), but not for the nuclear receptor corepressor, NCoR. The DNE of six natural TRs and four artificially constructed mTRs was assayed using a TR reporter gene containing TRE-DR4 (DR=direct repeat), TRE-pal (pal=palindrome) or TRE-lap (lap=inverted palindrome) in CV1 cells treated with 10 nM T(3). Of the mTRs examined, F451X (with a carboxy-terminal 11-amino-acid truncation) identified in a patient with RTH exhibited the strongest DNE on all TREs. The binding affinities between mTRs and corepressors SMRT or NCoR were quantified using a two-hybrid interference assay system consisting of VP16-TR(LBD) (LBD=ligand binding domain) and Gal4(DBD)-SMRT (DBD=DNA binding domain), or Gal4(DBD)-NCoR respectively, together with the Gal4 reporter gene. In this assay, VP16-TR(LBD) and Gal4(DBD)-SMRT (or Gal4 (DBD)-NCoR) interact with each other and trans-activate the Gal4 reporter gene. When an equal amount of mTR is coexpressed, it reduces the transcriptional activity of the reporter gene, depending on its binding avidity for a corepressor. A very strong correlation was observed between the SMRT-binding activity and the potency of the DNE among six natural mTRs and also among all mTRs, including four artificially constructed ones. The relationship between NCoR and DNE, however, was not significant. When we assayed the binding avidity of mTRs for RXR by using a two-hybrid assay system consisting of Gal4(DBD)-RXR(LBD) and VP16-TR(LBD), a significant correlation between DNE and binding avidity for the RXR was also observed. These results suggest that a corepressor plays an important role in DNE pathogenesis.

Translocation of regucalcin to rat liver nucleus: involvement of nuclear protein kinase and protein phosphatase regulation

The translocation of regucalcin to the nuclei of normal rat liver was investigated. The existence of endogenous regucalcin in isolated liver nuclei was confirmed by Western blotting using anti-regucalcin antibody. Nuclear translocation of regucalcin was estimated by sodium sulfate-polyacrylamide gel electrophoresis analysis. When isolated liver nuclei were incubated in the presence of exogenous regucalcin (50 microg/ml; 1.5 microM), potent band for regucalcin was found in the nuclei, indicating that the protein is translocated into the nucleus. This translocation was an early event. Nuclear regucalcin translocation was not appreciably changed in the presence of adenosine 5'-triphosphate (2 mM), guanosine 5'-triphosphate (2 mM), calcium chloride (0.1 mM), and the lectin wheat germ agglutinin (50 or 100 microg/ml), suggesting that its translocation is not mediated through nuclear localization signal. Moreover, Ca2+-dependent protein kinase and protein tyrosine phosphatase activities in isolated liver nuclei were significantly increased in the presence of anti-regucalcin monoclonal antibody (100 ng/ml) in the enzyme reaction mixture, and these increases were completely abolished by the addition of regucalcin (50 microg/ml). This study demonstrates that regucalcin is translocated into liver nucleus, and that it can regulate the nuclear function.