Increased expression of queuosine synthesizing enzyme, tRNA-guanine transglycosylase, and queuosine levels in tRNA of leukemic cells

Queuosine is a modified nucleoside located at the first position of the tRNA anticodon, which is synthesized by tRNA-guanine transglycosylase (TGT). Although the levels of queuosine in cancer cells have been reported to be lower than those in normal cells, the expression levels of TGT remain to be determined. We determined the expression levels of a subunit of TGT (TGT60KD). Contrary of our expectations, the results revealed higher levels of expression of TGT60KD than that in normal cells, and the level of queuosine in the tRNA fraction corresponded with that of TGT60KD expression. These results suggest the possibilities that the expression levels of TGT60KD regulate TGT activity and the levels of queuosine, and that TGT60KD plays significant roles in carcinogenesis. To our knowledge, this is a first report of increased expression levels of TGT60KD in human cancer cells.

A transposon carrying the gene mphB for macrolide 2'-phosphotransferase II

The mphB gene for macrolide 2'-phosphotransferase II is located on two plasmids, pTZ3721 and pTZ3723, in Escherichia coli BM2506. We examined translocation of mphB that originated from pTZ3721. The transposable element carrying mphB is 39 kb long and has a Tn21-like transposition module at one end and a Tn1721-like transposition module at other. The structure of the transposition modules of this element resembles that of Tn2610. However, the gene arrangement of the internal region on the transposon carrying mphB was reverse to that of Tn2610. The nucleotide sequences of both terminal regions suggested that the inversion of the DNA fragment occurred between the res sites by resolvase-mediated recombination.

Regulation of transcription of the mph(A) gene for macrolide 2'-phosphotransferase I in Escherichia coli: characterization of the regulatory gene mphR(A)

The synthesis of macrolide 2'-phosphotransferase I [Mph(A)], which inactivates erythromycin, is inducible by erythromycin. The expression of high-level resistance to erythromycin requires the mph(A) and mrx genes, which encode Mph(A) and an unidentified protein, respectively. We have studied the mphR(A) gene, which regulates the inducible expression of mph(A). An analysis of the synthesis of Mph(A) in minicells and results of a complementation test indicated that mphR(A) is located downstream from mrx and that its product, MphR(A), represses the production of Mph(A). DNA sequencing indicated that the mph(A), mrx, and mphR(A) genes exist as a cluster that begins with mph(A) and that the deduced amino acid sequence of MphR(A) can adopt an alpha-helix-turn-alpha-helix structure. To study the regulation of gene expression by MphR(A), we performed Northern blotting and primer extension. A transcript of 2. 9 kb that corresponded to the transcript of mph(A) through mphR(A) was detected, and its level was elevated upon exposure of cells to erythromycin. Gel mobility shift assays and DNase I footprinting indicated that MphR(A) binds specifically to the promoter region of mph(A), and the amount of DNA shifted as a results of the binding of MphR(A) decreased as the concentration of erythromycin was increased. These results indicate that transcription of the mph(A)-mrx-mphR(A) operon is negatively regulated by the binding of a repressor protein, MphR(A), to the promoter of the mph(A) gene and is activated upon inhibition of binding of MphR(A) to the promoter in the presence of erythromycin.

N-[[1-(2-phenylethyl)pyrrolidin-2-yl]methyl]cyclohexanecarboxamides as selective 5-HT1A receptor agonists

A series of benzamides was synthesized as selective agonists for the 5-HT1A receptor. It was found that (S)-N-[[1-(2-phenylethyl)pyrrolidin-2-yl]methyl]cyclohexanecarb oxamide(7-(S)) has potent and selective agonistic activity for the 5-HT1A receptor (5-HT1A; Ki 0.49 nmol/L, D2; IC50 = >1000 nmol/L, 5-HT2; Ki = 240 nmol/L).

[Drug Compliance Scale. I. Development of the Drug Compliance Scale]

The failure of patients to comply with treatment regimens recommended by their physicians is a significant clinical problem. Researches on the assessment of compliance have, however, been precluded by methodological difficulties such as lack of adequate measures. The purpose of this study was to develop a self-administered questionnaire to evaluate drug compliance. First, questionnaire containing a 52-items complied by two doctors, a pharmacist and a nurse, was tested on 81 outpatients, all volunteers, attending the departments of psychosomatic medicine and internal medicine. Four items were temporarily removed for later analysis because they directly inquired about drug compliance (drug compliance items). The other 48 items were analyzed and three factors consisting of 26 items were further studied: expectation on taking medicine, rejection to taking medicine and seeking knowledge of drugs. Chronback's alpha coefficients representing internal consistency of the three factors were sufficiently high (ranging from .75 to .84). Furthermore, we preformed a simplified pill count to validate the 4 drug compliance items. There was a weak to moderate correlation between the result of pill count and each of 4 drug compliance items. A new self-administered questionnaire of 30 items was thus developed and named the Drug Compliance Scale.

[Drug Compliance Scale. II. Psychological factors affecting drug compliance in the department of psychosomatic medicine]

The purpose of this study was to investigate psychological factors affecting drug compliance in the department of psychosomatic medicine. Seventy-four outpatients were asked to answer a battery of self-administered questionnaire including the Drug Compliance Scale (DCS) that we had recently developed and other questionnaire evaluating psychological and vegetative symptoms, self-efficacy and attributional styles on the promotion of health and personality closely related to interpersonal relationships. Results of path analysis indicated that attributional styles and self-efficacy mainly affected three factors of DCS such as expectation on taking medicine, rejection to taking medicine and seeking knowledge of drugs, through which they influenced drug compliance, and also indicated that personality and self-efficacy mainly affected the stability of mood state, suggesting a further influence on drug compliance.

Changes of the thromboxane A2/prostacyclin balance in the urine of patients with renal diseases analyzed by gas chromatography/selected ion monitoring

The thromboxane A2/prostacyclin (TX/PGI) ratios were measured in patients with renal diseases to elucidate the relationship between the ratios and the pathological changes of the diseases. Urinary stable metabolites of thromboxane A2 and prostacyclin, 11-dehydro-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1alpha, respectively, were converted to 1-methyl ester-propylamide-9,12,15-tris-dimethylisopropylsilyl ether derivative and 1-methyl ester-6-methoxime-9,12,15-tris-dimethylisopropylsilyl ether derivative, respectively, and applied to a gas chromatography/selected ion monitoring. The TX/PGI ratios of 10 outpatients and 6 inpatients with chronic glomerulonephritis were higher than those of 13 healthy volunteers. In an inpatient with systemic lupus erythematoides, the TX/PGI ratios were gradually lowered to the normal level with the therapies. Furthermore, the ratios seemed to change in advance of the changes of the levels of urinary protein and hematuria. These observations suggested that the TX/PGI ratio was a useful index to assess the pathological condition of renal diseases and the effects of treatment.

Auditory and visual P300 topography from a 3 stimulus paradigm

OBJECTIVE

The P300 event-related brain potential (ERP) was elicited with auditory and visual stimuli in a separate session of a 3 stimulus oddball paradigm, and the scalp topography was assessed with 15 electrode locations.

METHODS

Target (0.10), standard (0.80), and infrequent non-target (0.10) stimuli in the auditory task were 2000, 1000 and 500 Hz tone, and in the visual task, 'X', 'O', and 'H', respectively. The stimuli were presented in a random series, once every 2 s, and participants responded only to the target (N = 12).

RESULTS

Target stimuli elicited larger P300 components than non-target did in both stimulus modalities. For both target and non-target stimuli, P300 amplitude was larger and latency longer for the visual compared with the auditory stimulus. Analysis of normalized P300 amplitude data indicated that the target and non-target P300s from both modalities had identical topography.

CONCLUSION

The findings suggest that both target and non-target stimuli in 3 stimulus oddball paradigm elicited the same type of P300 (P3b) for both stimulus modalities.

Excitatory amino acid responses in relay neurons of the rat lateral geniculate nucleus

Responses to glutamate receptor agonists were recorded from identified relay neurons in the dorsal lateral geniculate nucleus of the rat, using the nystatin-perforated patch-clamp technique. Rapid application of glutamate, N-methyl-D-aspartate, (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and kainate induced inward currents at a holding potential of -44 mV. The responses to low concentrations of each agonist were composed only of steady-state currents, but the responses to high concentrations were additionally composed of a rapid transient peak component except in the kainate-induced current. The currents induced by 10(-3)M N-methyl-D-aspartate in the external solution containing 0 mM Mg2+ and 10(-6)M glycine were reduced in amplitude when the external solution contained 1 mM Mg2+, and were abolished when the solution contained no glycine. The currents induced by a neurotransmitter candidate at retinogeniculate synapses, N-acetyl-aspartyl-glutamate, were markedly reduced in amplitude when the solution contained 1 mM Mg2+ or 10(-4)M DL-2-amino-5-phosphonovaleric acid. The current abolished in the Mg2+-containing, glycine-free solution (N-methyl-D-aspartate component) and the current remaining in the same solution (non-N-methyl-D-aspartate component) of the N-acetyl-aspartyl-glutamate response were both increased in a concentration-dependent manner, as the N-acetyl-aspartyl-glutamate concentration was increased. The current-voltage relationship of the currents induced by N-methyl-D-aspartate and N-acetyl-aspartyl-glutamate was characterized by Mg2+-dependent block at hyperpolarized potentials. The inward currents induced by 3 x 10(-4)M AMPA and 3 x 10(-4)M glutamate were markedly potentiated by 10(-4)M cyclothiazide, but the currents induced by 3 x 10(-4)M kainate and 10(-3)M N-acetyl-aspartyl-glutamate (non-N-methyl-D-aspartate component) were little affected. The currents induced by any agonist were not affected by 3 x 10(-4)g/ml concanavalin A. The current induced by 10(-4)M kainate was markedly suppressed by pretreatment with 10(-4)M AMPA or 10(-4)M glutamate, but only weakly by 10(-3)M N-acetyl-aspartylglutamate. The Ca2+ permeability (PCa/PCs) of the N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors was 9.57 and 0.16, respectively. These results suggest that dorsal lateral geniculate nucleus relay neurons of the rat possessed both Ca2+-permeable N-methyl-D-aspartate receptors and less permeable non-N-methyl-D-aspartate (presumably AMPA) receptors, and that N-acetyl-aspartyl-glutamate mainly acts at N-methyl-D-aspartate receptors with a weak kainate-like action on non-N-methyl-D-aspartate receptors.

Nucleotide sequence of the gene cluster containing the mphB gene for macrolide 2'-phosphotransferase II

Escherichia coli BM2506 produced macrolide 2'-phosphotransferase II [MPH (2') II]. A gene for MPH (2') II, designated mphB, is located on plasmids pTZ3721 and pTZ3723 in E. coli BM2506. In the present study, we determined the nucleotide sequence of the 6.5-kb EcoRI-PstI fragment containing mphB on pTZ3721. The DNA region of 6.5-kb EcoRI-PstI fragment contained five open reading frames (ORFs). ORF4 corresponded to mphB. Respective products deduced from ORF1, ORF2, ORF3, and ORF5 were similar to the penicillin-binding protein 4 of Streptomyces lactamduras, the repressor protein AcrR of the acrAB operon, the enzyme RdmC involved in the biosynthesis of the antibiotic aklavinone, and IS801 transposase-like protein from Pseudomonas pseudoalcakigenes, respectively. Among these genes, ORF2, ORF3, and mphB formed a gene cluster with ORF2 in the lead sequence. Our results suggest that mphB may originate from an operon related to antibiotic biosynthesis.

ERPs, semantic processing and age

ERPs (N400, LPC and CNV) were elicited in two sets of subjects grouped according to age (young vs. elderly) using a word-pair category matching paradigm. Each prime consisted of a Japanese noun (constructed from two to four characters of the Hiragana) followed by one Chinese character (Kanji) as the target, this latter representing one of five semantic categories. There were two equally probable target conditions: match or mismatch. Each target was preceded by a prime, either belonging to, or not belonging to, the same semantic category. The subjects were required to respond with a specified button press to the given target according to the condition. We found RTs to be longer in the elderly subjects and under the mismatch condition. N400 amplitude was reduced in the elderly subjects under the mismatch condition and there was no difference between match and mismatch response, which were similar in amplitude to that under match condition for the young subjects. In addition, the CNV amplitudes were larger in the elderly subjects. These results suggested that functional changes in semantic processing through aging (larger semantic networks and diffuse semantic activation) were the cause of this N400 reduction, attributing a subsidiary role to attentional disturbance. We also discuss the importance of taking age-related changes into consideration in clinical studies.

Isolation and characterization of two plasmids that mediate macrolide resistance in Escherichia coli: transferability and molecular properties

Escherichia coli BM2506 is highly resistant to macrolide antibiotics; it produces macrolide 2'-phosphotransferase II [MPH(2')II] which inactivates such drugs. We investigated the localization and the transfer of the macrolide-resistance determinant that encoded the mphB gene for MPH(2')II in strain BM2506. Although we detected no clear band of plasmid DNA after agarose gel electrophoresis, transformation analysis using satellite DNA that corresponded to plasmid DNA after CsCl-ethidium bromide gradient centrifugation and restriction analysis of plasmid DNA in transformants showed that strain BM2506 harbored two plasmids, pTZ3721 (84 kb) and pTZ3723 (24 kb), that specified resistance to macrolides, ampicillin, streptomycin, tetracycline and sulfonamide and to macrolides and ampicillin, respectively. Southern hybridization showed that the mphB gene hybridized to both plasmids. Furthermore, pTZ3721 was transferred by conjugation to another strain of E. coli and pTZ3723 was mobilized with a self-transferable plasmid RP1 to other strains of E. coli. Therefore, it appears that the mphB gene is located on two plasmids in BM2506 and can be transferred to other strains of E. coli by conjugation or mobilization.

Expression of the mphB gene for macrolide 2'-phosphotransferase II from Escherichia coli in Staphylococcus aureus

The genes mphA and mphB encode macrolide 2'-phosphotransferases I and II, respectively, and they confer resistance to macrolide antibiotics in Escherichia coli. To study the expression of these genes in Gram-positive bacteria, we constructed recombinant plasmids that consisted of an mph gene and the pUB110 vector in Bacillus subtilis. When these plasmids were introduced into Staphylococcus aureus, the mphB gene was active and macrolide 2'-phosphotransferase II was produced. The gene endowed S. aureus with high-level resistance to spiramycin, a macrolide antibiotic with a 16-membered ring. Moreover, transcription of the mphB gene in S. aureus began at the promoter that was active in E. coli.

Expression in Pseudomonas aeruginosa of an erythromycin-resistance determinant that encodes the mphA gene for macrolide 2'-phosphotransferase I from Escherichia coli

We studied the expression in Pseudomonas aeruginosa of an erythromycin-resistance (EMr) determinant that included the mphA gene for macrolide 2'-phosphotransferase I and originated in Escherichia coli. A recombinant plasmid, pTZ3609, that consisted of the EMr determinant and a broad-host-range vector RSF1010, endowed P. aeruginosa with high-level resistance to erythromycin. Furthermore, the EMr determinant on a self-transferable plasmid, RP1, was transferred from E. coli to P. aeruginosa by conjugation.

Stimulus context determines P3a and P3b

P300 differences for target (.10), nontarget (.10), and standard tones (.80) were assessed using a three-stimulus oddball paradigm in which participants responded only to the target (n = 12). Target/standard (easy or difficult) and nontarget/standard (large or small) pitch differences were manipulated orthogonally. In all conditions, target tones elicited a parietal P300, which was affected only by the target/standard discrimination ease. Nontarget in the easy/large and difficult/small conditions elicited a parietal but smaller P300 than the target but in the easy/small condition elicited similar ERPs to the standard. However, nontarget stimuli in the difficult/large condition elicited an anterior maximum and earlier P300 (P3a) component. The findings suggest that target P300s are not influenced by the nontarget stimulus configuration, whereas the nontarget P300 outcomes are determined directly by the stimulus context. The theoretical implications are discussed.

Discovery of a novel thrombopoietin mimic agonist peptide

A random phage peptide library was constructed for the filamentous bacteriophage fuse5. The library was made by inserting a degenerate oligonucleotide which encodes 15 variable amino acids into the NH2-terminal region of the phage gene III protein. This library, containing 1x10(9) different phages, was screened with a human immunoglobulin fusion protein containing the extracellular region of human thrombopoietin receptor. Several phages were isolated following four cycles of enrichment and amplification. These phages specifically bound to the fusion protein. One phage peptide acted as an agonist of the thrombopoietin receptor, since it stimulated the proliferation of thrombopoietin-dependent cells and the differentiation of mouse bone marrow cells to megakaryocytes. The amino acid sequence of this peptide is not present in the primary amino acid sequence of thrombopoietin. This discovery may lead to the design of a small-molecular mimic of thrombopoietin.

A solid-phase assay to screen monoclonal antibodies against DNA-binding protein

A method is described for selecting monoclonal antibodies (mAb) against DNA-binding protein. The protocol involves a non-radioactive solid-phase DNA binding assay using a 96-well plate. Because the solid-phase assay is highly specific and sensitive, partially purified antigen is sufficient for the immunization, and mAb screening can be performed with crude cell extract as the antigen. MAbs obtained by this method could supershift the DNA-protein complex in the electromobility shift assay, and were sufficient for immunoscreening of a cDNA expression library.

Comparison of ultrastructural changes in thyrotrophs of the rat pituitary between intermittent and continuous treatments with sulfadimethoxine

To clarify relationships between serum thyroid-stimulating hormone (TSH) levels and ultrastructural changes in thyrotrophs caused by intermittent or continuous treatments with antithyroid compound, male Fischer-344 rats initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN) were given water containing 0.1% sulfadimethoxine (SM) for 8 wk and then sacrificed (Group 1). Additional groups were examined 2 wk after withdrawal (Group 2), after 4 wk retreatment following a 2-wk withdrawal period (Group 3), and after 14 wk continuous exposure (Group 4). Control rats (Group 5) remained untreated for 8 wk after the DHPN initiation. Microscopic examination revealed hypertrophy of thyrotrophs and depletion of TSH-positive material in Groups 1, 3, and 4 but a return to normal in Group 2. Electron microscopic examination of thyrotrophs in the anterior pituitary in Groups 1, 3, and 4 revealed dilated rough endoplasmic reticulum (ER) cisternae with intracisternal dense granules as well as diminished numbers of intracytoplasmic secretory granules, these changes being most marked in Group 1 and least pronounced in Group 4. The number of intracytoplasmic secretory granules in Group 3 was much lower than in Group 4, as demonstrated by morphometric analysis. In Group 2, thyrotrophs showed dilated rough ER cisternae without intracisternal dense granules and essentially the same component of intracytoplasmic secretory granules as Group 5. The present study suggest that while prolonged continuous treatment with SM results in gradual acclimation to an increased demand for TSH, intermittent treatment elicits a persistent state of reduced TSH storage in thyrotrophs due to a continued strong feedback through the hypothalamus-pituitary-thyroid axis.

Characterization of the K+ current mediated by 5-HT1A receptor in the acutely dissociated rat dorsal raphe neurons

The action of 5-hydroxytryptamine (5-HT) via the 5-HT1A receptor on dissociated rat dorsal raphe neurons was characterized under the whole-cell mode by using the nystatin-perforated patch-clamp technique. Under voltage-clamp conditions, 5-HT induced an inwardly rectifying K+ current (I5-HT) in a concentration-dependent manner. I5-HT was mimicked by 8-OH-DPAT and buspirone, which are both 5-HT1A receptor agonists. I5-HT was reversibly blocked by such 5-HT1A receptor antagonists as (S)-UH-301 a 5-HT4 receptor antagonist. I5-HT was antagonized concentration-dependently by such K+ channel blockers as quinine, Ba2+ and 4-aminopyridine but was relatively insensitive to both CS+ and tetraethylammonium. When the neurons were loaded with guanosine 5'-O-3-thiotriphosphate through a patch pipette, the K+ current induced by 5-HT became irreversible. N-ethylmaleimide (NEM), a sulfhydryl alkylating agent, irreversibly blocked I5-HT. The intracellular perfusion with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a Ca2+ chelator, or neomycine, a phospholipase C inhibitor, never significantly affected the 5-HT-induced response. 12-Myristate 13-acetate diester (PMA), a protein kinase C (PKC) activator, had only a weak inhibitory effect on I5-HT, and staurosporine, a PKC inhibitor, failed to significantly occlude I5-HT. Therefore, the K+ conductance activated via the 5-HT1a receptor of dorsal raphe neurons was thus characterized by the sensitivity to such K+ channel blockers as quinine, Ba2+ and 4-aminopyridine. Moreover, G protein which is NEM-sensitive and can couple to the 5-HT1A receptor, is thus considered to activate the inwardly rectifying K+ conductance without being mediated by such second messengers as Ca2+ and PKC.

Cloning and nucleotide sequence of the mphB gene for macrolide 2'-phosphotransferase II in Escherichia coli

Macrolide 2'-phosphotransferase II [MPH(2')II] inactivates macrolide antibiotics. The mphB gene for MPH(2')II was cloned from Escherichia coli and sequenced. Analysis of the nucleotide sequence indicated that mphB encoded a protein of 302 amino acids with a molecular mass of 34483 Da. The carboxy terminal region of the deduced protein contained a sequence that resembled a conserved functional domain in aminoglycoside phosphotransferases.

P300, probability, and the three-tone paradigm

The effects of stimulus probability on P300 from a 3-tone paradigm were examined in two experiments. Experiment 1 manipulated the probability of the non-target tone as 0.10, 0.45, or 0.80, while the target tone probability was always 0.10. Experiment 2 manipulated the probability of 3 tones as 0.10, 0.30, or 0.60, with one of the infrequent tones assigned as the target in each condition. Subjects were required to press a button in response to the target stimulus in both experiments. The results indicated that the P300 to the target and the non-target were both affected by the probability of the eliciting stimulus, such that component amplitude was inversely related to probability; no reliable P300 latency effects were found. Target tones elicited larger P300 amplitude than the non-target tones at the same probability. The findings suggest that probability effects on P300 amplitude are independent of responding to a specific target stimulus and are discussed with reference to the clinical utility of the 3-tone paradigm.

P300 from one-, two-, and three-stimulus auditory paradigms

P300 event-related potentials (ERPs) from 1-, 2-, and 3-tone oddball paradigms were elicited and compared from the same subjects. In the 1-tone paradigm, only a target tone was presented, with the standard tone replaced by silence. The 2-tone paradigm was a typical oddball task, wherein the target and standard tones were presented every 2.0 s in a random order with a target-tone probability of 0.10. In the 3-tone paradigm, in addition to the infrequent target (p = 0.10) and the frequent standard (p = 0.80), infrequent nontarget tones (p = 0.10) also were presented. The subject responded with a button press only to the target stimulus in each task. The target stimulus in each paradigm elicited a P300 component with a parietal maximum distribution. No P300 amplitude differences were found among paradigms, although peak latency from the 1-tone paradigm was shorter than those from the other two tasks. Both P300 peak amplitude and latency demonstrated strong positive correlations between each pair of paradigms. The results suggest that P300 was produced by the same neural and cognitive mechanisms across tasks. The possible utility of each paradigm in clinical testing is discussed.

Two components of metabotropic glutamate responses in acutely dissociated CA3 pyramidal neurons of the rat

The excitatory and inhibitory actions of metabotropic glutamate receptor (mGluR) agonists were investigated in acutely dissociated rat hippocampal CA3 pyramidal neurons, using the conventional whole-cell and nystatin-perforated patch recording configurations under the voltage-clamp condition. With the conventional whole-cell recording, glutamate (Glu) and quisqualic acid (QA) induced only ionotropic inward currents accompanied by increased membrane conductance at a holding potential (VH) of -45 mV. The response was reversibly blocked in the presence of D-2-amino-5-phosphonopentanoic acid (D-AP5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), the antagonists of N-methyl-D-aspartate (NMDA) receptor and non-NMDA receptor, respectively. With nystatin-perforated patch recording, mGlu responses insensitive to both D-AP5 and CNQX were observed. Fifty-five % of the cells responded by a slow inward current accompanied by conductance decrease (ImGlui) at a VH of -44 mV. One % of the neurons showed an outward current with conductance increase (ImGluo), and 34% of the neurons showed ImGluo followed by ImGlui. The onset of ImGluo occurred approximately 900 ms after the response to 30 mM K+. The time to peak of ImGluo were 32- to 79-times longer than those of ionotropic responses. ImGlui appeared at lower concentrations than ionotropic Glu responses, whereas ImGluo appeared at similar concentrations as ionotropic responses. The rank order of affinity was QA > Glu > (+/-)-1-aminocyclopentane-trans-1, 3-dicarboxylic acid (tACPD) for both ImGlui and ImGluo. Half-maximal effective concentrations (EC50) and the threshold concentrations for the three agonists were four- to tenfold lower for ImGlui than for ImGluo. The current-voltage relationship showed that the reversal potentials of ImGlui and ImGluo shifted 55 and 59 mV, respectively, for a tenfold change in extracellular K+ concentration, indicating that K+ is the charge carrier of both mGlu responses. During ImGlui, both the leakage current and muscarine-sensitive voltage-dependent K+ current (M current) were suppressed. ImGluo induced by 10(-4) M tACPD was abolished by 3.10(-7) M charybdotoxin and 10(-6) M ryanodine. These results show that there are two components of mGlu responses in CA3 pyramidal neurons and that ImGlui and ImGluo show different pharmacological properties.

[Functional imaging of the sensorimotor cortex using an ultra-fast MR imaging method]

The aim of this study was to assess changes in brain activity during a motor task and variable sensory stimulation using echo planar imaging, which represents the fastest clinically usefull imaging technique available.

MATERIALS AND METHODS

The subjects of this study were 11 healthy-volunteers, 4 males and 11 females, with an average of 26.4 years. The subjects were instructed to tap the fingers of one hand as the motor task. Compressed air was applied 5 times a second as "simple" sensory stimulation. Simple figures were drawn on the subjects palm as "complex" sensory stimulation. In all cases, functional imaging was performed by T2*-weighted echo planar imaging (TE = 53 msec, TR = 3000 msec, flip angle = 90 degrees, matrix 64 x 64, FOV = 205 mm, slice thickness = 8 mm) alternately at rest and during the task (intervals: 30 sec). A total of 60 images was collected in 3 minutes. Images obtained by subtracting images at rest and during the task were analyzed.

RESULTS AND DISCUSSION

Almost all subjects showed a transient signal increase in the contralateral paracentral region during simple sensory stimulation. Continuous signal increases in the contra- and/or ipsi-lateral para-central region were observed during complex sensory stimulation. Some exhibited signal increases in the parietal or frontal association cortex, but they disappeared when subject's attention was distracted during stimulation. All subjects displayed signal increases in the contralateral para-central region during the motor task. Some of them exhibited signal increases in the medial frontal area (supplementary motor area) and ipsilateral para-central region. These results suggest that the signal increases of functional MRI reflect not only simple reactions to stimulation but higher cerebral function as well.

Effect of rat thyroid proliferative lesion development by intermittent treatment with sulfadimethoxine

To determine whether production of thyroid proliferative lesions would be enhanced by intermittent rather than continuous treatment with a goitrogen, male F344 rats initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN, 2800 mg/kg body weight, single s.c. injection) were given water containing 0.1% sulfadimethoxine (SM) for 20 weeks (group 1) or 0.1% SM for the first 8 weeks followed by 2 cycles consisting of 2 weeks withdrawal and 4 weeks retreatment with 0.1% SM (group 2). Control rats (group 3) were untreated for 20 weeks after the DHPN initiation. Serum T3 and T4 levels were significantly decreased in groups 1 and 2 compared to group 3. Serum thyroid stimulating hormone level was significantly increased in all treated groups compared to group 3. The numbers of follicular cell hyperplasias were significantly increased in group 2 compared to group 1. BrdU labeling indices for follicular cells and hyperplasias were also significantly elevated in group 2 compared to group 1. Electron microscopic examination of thyrotrophs in the anterior pituitary in groups 1 and 2 revealed dilated rough ER cisternae with intracisternal dense granules. The number of intracytoplasmic secretory granules in group 2 was moderately decreased compared to group 1. Therefore, the results of the present study suggest that it may be possible to enhance production of thyroid neoplastic lesions by intermittent treatment.

The measurement of intracellular sodium ion concentration in the horizontal cells of the stingray retina

Membrane potentials, and intracellular concentrations of sodium ions in the horizontal cells of the stingray retina were measured directly by means of ion-selective microelectrodes. The electrodes used were of the double-barreled type and bis[(12-crown-4)methyl]methyldodecylmalonate was used as the ion-selective resin. The average intracellular concentration of Na+ ions in the horizontal cells and the extracellular concentration of Na+ ions near the horizontal cells were 123 mM and 351 mM, respectively (n = 27). The equilibrium potential was estimated to be +27.3 mV. Although each value of the equilibrium potential was scattered over a wide range, they were always positive regardless of the membrane potential. This was the first direct measurement of the sodium ion-concentration for the retinal horizontal cells. The results support the idea that the origin of the dark depolarization of the stingray horizontal cell is caused by the glutamate-induced high-sodium conductance of the membrane.

Negative brain potentials elicited by an unexpected color patch or word

The purpose of this study was to examine whether a physical stimulus that deviates from a semantic context can elicit the N400 component of event-related brain potentials (ERPs). ERPs were recorded while 12 students judged the veracity of a simple statement (e.g., red/is not/blue) presented with the order of subject (S), object (O), and verb (V), which is normal in Japanese grammar. In one condition, S was a color patch and O was a word representing the color, while in the other condition, S was a color name and O was a patch. In both conditions, a late additional negative potential was elicited by the O stimulus when it was mismatched with S. In addition, the negativities elicited by the incongruous color patch and word had the same morphology and scalp distribution. The results indicate that not only a word but a physical stimulus which deviates from a semantic context can elicit the N400 component.

Intracellular and extracellular chloride ions in the horizontal cells of the stingray retina

Intracellular and extracellular concentrations of chloride ([Cl-]i, [Cl-]o) ions in the horizontal cells of the stingray retina were studied by means of ion-selective microelectrodes. The electrodes used were of the double-barreled type and Corning's #477315 resin was used as the exchanger. The average [Cl-]o and [Cl-]i in the L-type cells were 320 and 130 mM, respectively (n = 37), and the equilibrium potential (ECl) was calculated as -23.3 mV. In some cases, dark membrane potentials were more positive than the ECl. With white light stimulus, the membrane hyperpolarized to a more negative level than ECl. Based on the experiments described above, the hypothesis that the hyperpolarizing response of horizontal cells is due to the permeability change of the membrane to chloride ion was excluded in the stingray retina.

Negative brain potentials reflect the subjective distance between standard and deviant tones

The purpose of this study was to examine the effects on event-related brain potentials (ERPs) of occasionally presented deviants in a sequence of tones. The sequence consisted of a series of frequent standard C5 tones from the diatonic musical scale, in which three deviants (F #5, C6, and F #6) and a target (C4) were occasionally embedded. Twenty subjects were asked to detect the target. The deviants elicited frontal N2. The amplitude of the N2 was smaller for C6 than for the other two deviants, whereas peak latencies increased as a function of the frequency distance between the deviant and the standard. The smaller N2 to C6 than that to the other deviants was considered to reflect closer subjective distance due to the octave relationship between C6 and the standard C5.

Sentence verification and event-related brain potentials

The purpose of this study was to examine whether the decision process affected scalp recorded event-related brain potentials (ERPs). ERPs were recorded while 10 subjects evaluated the veracity of four types of Japanese sentences; true-affirmative (TA), true-negative (TN), false-affirmative (FA), and false-negative (FN). Each sentence was presented visually, one word at a time in the following order: Subject (S); object (O); and verb (V). This order of words, which is normal in Japanese grammar, allowed the ERP waveforms associated with semantic mismatch between the S and O occurring in the middle of the sentence to be separated from those elicited by the decision concerning the sentence's truth or falsity occurring at the end of the sentence. Semantic mismatch was associated with a negative component (N310) following the O-word. In addition, P3s were elicited by sentence final words. Affirmative sentences elicited larger P3s than did negative sentences, and true sentences elicited earlier P3s than did false sentences. P3s were smaller in amplitude when they followed a mismatch between the S and O words. The result suggested that by using Japanese sentences, it may be possible to examine sentence-level rather than word-level processes.

[A report of five cases of multiple cancer with hematologic malignancies]

Five patients with multiple cancers that included hematologic malignancies are described. The incidence of multiple cancers in hematologic malignancies has been 8.8% in the past two and a half years at our hospital. The combinations were: 1) primary bilateral breast cancers and acute monocytic leukemia; 2) breast cancer, malignant lymphoma and gastric cancer; 3) malignant lymphoma and gastric cancer; 4) malignant lymphoma and prostate cancer, and 5) colon cancer and multiple myeloma. Our experience suggests an increasing incidence of multiple cancer in hematologic malignancies.

Wegener's granulomatosis: successful treatment with high-dose cyclophosphamide

A 30-year-old male taxi driver developed extensive purpuric necrotic lesions all over his body. He had a consolidated shadow in the right upper lung field, proteinuria with microscopic hematuria, and granulomatous change in the nasal mucosa. The standard regimen of prednisolone alone or in combination with cyclophosphamide showed only a limited effect on the lesion. However, weekly intravenous injections of a high dose of cyclophosphamide (500 mg/week) in combination with 60 mg/day of prednisolone exhibited dramatical suppression of the disease activity.