Order by Quenched Disorder in the Model Triangular Antiferromagnet RbFe(MoO_{4})_{2}.

We observe a disappearance of the 1/3 magnetization plateau and a striking change of the magnetic configuration under a moderate doping of the model triangular antiferromagnet RbFe(MoO_{4})_{2}. The reason is an effective lifting of degeneracy of mean-field ground states by a random potential of impurities, which compensates, in the low-temperature limit, the fluctuation contribution to free energy. These results provide a direct experimental confirmation of the fluctuation origin of the ground state in a real frustrated system. The change of the ground state to a least collinear configuration reveals an effective positive biquadratic exchange provided by the structural disorder. On heating, doped samples regain the structure of a pure compound, thus allowing for an investigation of the remarkable competition between thermal and structural disorder.

Characteristics of sensori-motor interaction in the primary and secondary somatosensory cortices in humans: a magnetoencephalography study.

We studied sensori-motor interaction in the primary (SI) and secondary somatosensory cortex (SII) using magnetoencephalography. Since SII in both hemispheres was activated following unilateral stimulation, we analyzed SIIc (contralateral to stimulation) as well as SIIi (ipsilateral to stimulation). Four tasks were performed in human subjects in which a voluntary thumb movement of the left or right hand was combined with electrical stimulation applied to the index finger of the left or right hand: L(M)-L(S) (movement of the left thumb triggered stimulation to the left finger), L(M)-R(S) (movement of the left thumb triggered electrical stimulation to the right finger), R(M)-R(S) (movement of the right thumb triggered electrical stimulation to the right finger), and R(M)-L(S) (movement of the right thumb triggered electrical stimulation to the left finger). Stimulation to the index finger only (S condition) was also recorded. In SI, the amplitude of N20m and P35m was significantly attenuated in the R(M)-R(S) and L(M)-L(S) tasks compared with the S condition, but that for other tasks showed no change, corresponding to a conventional gating phenomenon. In SII, the R(M)-L(S) task significantly enhanced the amplitude of SIIc but reduced that of SIIi compared with the S condition. The L(M)-L(S) and R(M)-R(S) tasks caused a significant enhancement only in SIIi. The L(M)-R(S) task enhanced the amplitude only in SIIc. The laterality index showed that SII modulation with voluntary movement was more dominant in the hemisphere ipsilateral to movement but was not affected by the side of stimulation. These results provided the characteristics of activities in somatosensory cortices, a simple inhibition in SI but complicated changes in SII depending on the side of movement and stimulation, which may indicate the higher cognitive processing in SII.

Attenuation of the effect of remote muscle contraction on the soleus H-reflex during plantar flexion.

OBJECTIVE: We investigated to what extent the facilitation of the soleus (Sol) Hoffmann (H-) reflex during a phasic voluntary wrist flexion (Jendrássik maneuver, JM) can be modulated by graded plantar flexion force and conditioning wrist flexion force. METHODS: The subjects were asked to perform phasic wrist flexion under a reaction time condition. Sol H-reflex was evoked by stimulating the right tibial nerve at various time intervals (50-400ms) after the 'Go' signal for initiating JM while the ankle was at rest and while plantarflexing. The level of tonic plantar flexion force (isometric contraction of 10, 20 and 30% of maximal EMG) and conditioning wrist flexion (isometric contraction of 30, 50 and 80% of maximum voluntary contraction) during JM was graded systematically. RESULTS: Although JM facilitation could be seen 80-120ms after the flexor carpi radialis (FCR) EMG onset even while plantarflexing, the magnitude of JM facilitation under plantar flexion was significantly decreased compared to that at rest. The degree of decrease in JM facilitation did not depend on the level of plantar flexion force. In contrast, the degree of JM facilitation was proportional to the level of wrist flexion force while the ankle was at rest and while plantarflexing, though the amount of JM facilitation significantly decreased while plantarflexing. CONCLUSIONS: JM facilitation of Sol H-reflex is decreased while performing tonic voluntary contraction of the homonymous muscle. The degree of decrease in JM facilitation is independent of the level of homonymous muscle contraction, but depends on the level of remote FCR contraction. In clinical application, when we intend to elicit a maximum stretch reflex by JM, full relaxation of homonymous muscle should be carefully confirmed. SIGNIFICANCE: Our results provide evidence for better understanding of the features of JM and insight into its clinical application.

Factors affecting quality control of [18F]FDG injection: bacterial endotoxins test, aluminum ions test and HPLC analysis for FDG and CIDG.

High concentrations of citrates and phosphates which are often used in the manufacturing of [18F] fluro-D-glucose (FDG) preparations and wide deviation in the pH value from the neutral level often disturb the detection of endotoxins and aluminum ions using the turbidimetric and aluminum ion paper test method. The column temperature was found to be a major factor influencing the sensitivity of ClDG detection with the HPAEC/PAD method.

The proportion of cells with functional X disomy is associated with the severity of mental retardation in mosaic ring X Turner syndrome females.

Turner syndrome females (45,X) do not have mental retardation (MR), whereas some mosaic ring X Turner syndrome females, with 45,X/46,X,r(X), have severe MR. The MR is believed to be caused by a failure of X chromosome inactivation (XCI) of the small ring X chromosome, which leads to functional X disomy (FXD), To explore this hypothesis, we examined the proportion of FXD cells in the peripheral blood of four ring X Turner syndrome females with various levels of MR, using two newly developed XCI assays based on DNA methylation of X-linked genes. As a result, the two patients with extremely severe MR showed complete FXD patterns, whereas the remaining two patients with relatively milder MR showed partial FXD patterns. These results indicate that the proportion of FXD cells may be associated with the severity of MR in mosaic ring X Turner syndrome females, although this association should be confirmed by examining brain cells during development. One of the cases with severe MR and a complete FXD pattern neither lacked the XIST gene nor had uniparental X isodisomy, and we discuss the mechanism of the failure of XCI in this case.

Induction of various androgen-dependent esteroproteases (trypsin-like and chymotrypsin-like enzymes) by tri-iodo-L-thyronine in the submandibular glands of female mice and mice with testicular feminization.

Trypsin-like and chymotrypsin-like esteroprotease isozymes of the mouse submandibular gland were separated by isoelectric focusing. In normal female mice the following pI-isozyme activities were found; pI-4.6, -5.6 (shoulder), -5.8, -7.1, and -9.9, hydrolytic activities for benzoylarginine ethylester (BAEE) (trypsin-like enzymes), and pI-4.7 and -10.3 hydrolytic activities for acetyltyrosine ethylester (ATEE) (chymotrypsin-like enzymes). In mice with testicular feminization (Tfm mice), only pI4.6 hydrolytic activity for BAEE was found; no ATEE hydrolytic activity was detected. In normal female mice, both 5 alpha-dihydrotestosterone (5 alpha-DHT) and tri-iodo-L-thyronine (T3) significantly increased all these isozymes except the pI-4.6 hydrolytic activity for BAEE. In Tfm mice, T3 also increased all these isozymes except the pI-4.6 hydrolytic activity for BAEE, but 5 alpha-DHT had no effect on any enzymes. These results suggest that the pI-4.6 hydrolytic activity for BAEE is non-inducible by the two hormones. Androgen does not seem to be involved in the inductions of these esteroproteases by T3.

Morphology of a cytochrome c-adsorbed stearic acid monolayer on Brewster angle microscopy.

The morphologies of stearic acid and cytochrome c (cyt.c)-adsorbed stearic acid monolayers were investigated by Brewster angle microscopy (BAM) with various molecular areas of stearic acid. With an area of more than 0.38 nm2/molecule, many blight island domains and some bright circles were observed in the BAM image of the stearic acid monolayer. The blight site part became to occupy all the surface with compression, and then became more closely packed with an area of 0.22 nm2/molecule. On the other hand, a different BAM image was obtained for the cyt.c-adsorbed stearic acid monolayer, as follows: (i) a striped pattern was only observed in the presence of cyt.c; (ii) the number of bright circles in the presence of cyt.c was less than that in its absence. Furthermore, when a uniform BAM image was observed for the stearic acid monolayer with cyt.c, the intensity of the absorbance at 409 nm of cyt.c was the highest. By calculating the amount of cyt.c adsorbed on a stearic acid monolayer from the absorbance value, it was shown that cyt.c was most closely packed when an uniform BAM image was observed. These results suggest that the use of BAM and visible absorption spectroscopy together is useful for studying the morphology of a monolayer.

Novel chiral bisoxazoline ligands with a biphenyl backbone: preparation, complexation, and application in asymmetric catalytic reactions

Novel C(2)-symmetric chiral bisoxazoline ligands 1 were easily prepared from enantiomerically pure 2-amino alcohols and achiral 2, 2'-biphenyldicarboxylic acid via the corresponding amide and mesylate as intermediates. Since these ligands bear only two ortho-substituents on the biphenyl backbone, the biphenyl axis is not fixed, and the two diastereomers of these ligands exist in equilibrium in solution. Interestingly, when the ligands 1 were coordinated with a metal ion, only one of the two possible diastereomer complexes, an (S,aS,S)-complex, can be formed depending on the combination of the ligand and the metal ion. Thus, copper(I) afforded only the (S,aS,S)-complexes with all ligands 1, while zinc(II), palladium(II), and silver(I) afforded the (S,aS, S)-complexes as the sole product only with 1b, which has a bulky tert-butyl group on the oxazoline ring, and a mixture of the two diastereomer complexes with 1a,c,d. The copper(I)-catalyzed asymmetric cyclopropanation of styrene with diazoacetate proceeded successfully with these ligands and good to excellent enantioselectivities were afforded.

Three point mutations of human butyrylcholinesterase in a Japanese family and the alterations of three-dimensional structure.

Three different mutations at codons 330 (TTA to ATA), 365 (GGA to AGA) and 515 (CGT to TGT) of human butyrylcholinesterase (hBChE) were identified in a Japanese family. We correlated alterations in in the patient's hBChE activity with possible structural alterations in the three-dimensional structure of hBChE caused by the point mutations. This study was performed using the published computer-generated three-dimensional structure of hBChE based on the structure of acetylcholinesterase. The amino acid substitution at L330I was adjacent to hydrophobic residues that form the channel domain of the active center. This side chain faced the side opposite the active center. The amino acid substitution at G365R was located at the position most remote from the active center, and this substitution site was exposed to the surface of the BChE protein. Alpha-helical structure was present to the active center, and the guanidyl residue of native Arg 515 was hydrogen-bonded to the carboxyl group of Asp 395 in the alpha-helix. These point mutations may cause steric effects on the present patient's hBChE activity. This is the first report of three-dimensional structural analysis performed on the L330I, G365R, and R515C mutations of hBChE.

Metabolite analysis of [11C]Ro15-4513 in mice, rats, monkeys and humans.

We performed in vitro and in vivo assays of the metabolism of [(11)C]Ro15-4513 over time in the plasma of mice, rats, monkeys and humans, using a radio-HPLC equipped with a sensitive positron detector, in order to compare the metabolic rates of the radiopharmaceutical agent among the different animal species and to establish a highly sensitive analytical method for the radiotracer agent. We also examined the metabolism of [(11)C]Ro15-4513 in the brain tissue of mice and rats. The analytical method used in this study permitted detection of even extremely low levels of radioactivity (approximately 5,000 dpm). In vitro experiments revealed that [(11)C]Ro15-4513 in the blood was metabolized to hydrolysate [(11)C]A. The species were classified in descending order of the metabolic rate of the radiotracer in vitro as follows; mice, rats, and monkeys/humans. In the in vitro experiment, the percentage of the unchanged drug in the plasma at 60 minutes postdose was 9% in mice, 70% in rats, 97% in monkeys, and 98% in humans. In vivo metabolite analysis in the blood showed the presence of two radioactive metabolites, consisting of one hydrolysate [(11)C]A and another unidentified substance. The species were classified in descending order of the metabolic rate of the radiotracer in vivo as follows; mice, rats/humans, and monkeys. The percentage of the unchanged drug in the plasma was 6% in mice, 21% in rats, 26% in humans, and 40% in monkeys. Furthermore, the in vitro and in vivo experiments conducted to analyze the metabolism of [(11)C]Ro15-4513 in the brain tissue of mice and rats revealed that the radiotracer was metabolized to some extent in the brain tissue of these animals. In the in vivo experiment, the percentage of the unchanged drug at 60 min postdose was 86% in the brain tissue of mice and 88% in the brain tissue of rats, while in the in vitro experiment, the corresponding percentage was 93% in mice, and 91% in rats.

A strategy for increasing the brain uptake of a radioligand in animals: use of a drug that inhibits plasma protein binding.

A positron-emitter labeled radioligand for the glycine-binding site of the N-methyl-D-aspartate (NMDA) receptor, [(11)C]L-703,717, was examined for its ability to penetrate the brain in animals by simultaneous use with drugs having high-affinity separate binding sites on human serum albumin. [(11)C]L-703,717 has poor blood-brain barrier (BBB) permeability because it binds tightly to plasma proteins. Co-injection of warfarin (50-200 mg/kg), a drug that binds to albumin and resembles L-703,717 in structure, dose-dependently enhanced the penetration by [(11)C]L-703,717 in mice, resulting in a five-fold increase in the brain radioactivity at 1 min after the injection. Drugs structurally unrelated to L-703,717, salicylate, phenol red, and L-tryptophan, were less effective or ineffective in increasing the uptake of [(11)C]L-703,717. These results suggest that the simultaneous use of a drug that inhibits the binding of a radioligand to plasma proteins is a useful way to overcome the poor BBB permeability of the radioligand triggered by its tight binding to plasma proteins. In brain distribution studies in rodents, it was found that, after the increase in brain uptake with warfarin, much of the glycine site antagonist accumulates in the cerebellum but its pharmacological specificity did not match the glycine site of NMDA receptors.

Telomerase activity is down regulated via decreases in hTERT mRNA but not TEP1 mRNA or hTERC during the differentiation of leukemic cells.

BACKGROUND: Recent studies have determined several telomerase-associated molecules, but the precise mechanisms regulating telomerase activity by those molecules has not been fully understood. MATERIALS AND METHODS: The telomerase activity was determined by TRAP assay. Using TaqMan RT-PCR, the quantitative and kinetic values of mRNA expression of the three telomerase-associated molecules were examined in HL60 cells differentiated with tumor necrosis factor mutant and all-transretinoic acid. RESULTS: The levels of telomerase activity in leukemic cell lines, leukemic cells from patients, and normal peripheral blood cells were distributed over a very wide range. Human telomerase catalytic subunit (hTERT) mRNA expression declined to nearly undetectable levels more rapidly than the inhibition of telomerase activity after treatment with these reagents in HL60 cells. Telomerase-associated protein (TEP1) mRNA increased approximately 6-fold over its level in untreated cells. The levels of human telomerase RNA component (hTERC) also increased approximately 2.7-fold at 5 days after treatment. CONCLUSIONS: These results suggest that telomerase activity is down-regulated mainly via decreases in hTERT, but not TEP1 and hTERC expression during the differentiation of leukemic cells.

The fermentation, isolation and characterization of a macromolecular peptide antibiotic: AN-3.

A new macromolecular peptide antibiotic, named AN-3, was isolated from the culture broth of Streptomyces albulus. From 19 liters of culture broth containing AN-3 with 90 units/ml activity, a 400 mg sample with a specific activity of 109 units/mg was obtained. Purified AN-3 gave a single band on polyacrylamide gel electrophoresis. AN-3 was a basic polypeptide with a molecular weight of 12,000 approximately 12,500 and an isoelectric point of pH 7.6. It showed a peak of absorption at 280 nm and seemed to have no nonprotein chromophoric component. It was soluble in water but insoluble in ethanol, butanol and acetone, and was stable at pH 4 approximately 9 but unstable at pH2. AN-3 had no antibacterial activity against Gram-positive and Gram-negative bacteria so far as tested. But, it showed a strong inhibitory effect on a macromolecule permeable mutant of Escherichia coli. It was not mutagenic. It appeared to inhibit synthesis of DNA and RNA without affecting DNA itself. It also inhibited the in vitro cell growth of L1210 and its ED50 was 5 micrograms/ml. AN-3 had antitumor activity against Lewis lung carcinoma in mouse in vivo.

The fermentation, isolation and characterization of macromolecular peptide antibiotics: AN-7A, -7B and -7D.

A group of new macromolecular peptide antibiotics, named AN-7, was isolated from the culture broth of Streptomyces griseoincarnatus AJ9424. AN-7 was fractionated into three different components, A, B and D. From 18 liters of culture broth (78 units/ml), 10 mg of AN-7A with a specific activity of 2,053 units/mg, 9 mg of AN-7B (1,167 units/mg) and 11 mg of AN-7D (6,225 units/mg) were obtained. All of these samples gave single bands on polyacrylamide gel electrophoresis. They are acidic polypeptides with molecular weights ranging from 12,400 to 13,000. Their UV absorption spectra showed maxima peaks at 280 nm and shoulders at 290 nm. Each AN-7 component has a nonprotein chromophoric component. AN-7A, -7B and -7D have no antibacterial activity against the Gram-negative bacteria tested but strongly inhibit the growth of Gram-positive bacteria and Escherichia coli MP2, a macromolecule permeable mutant strain. The AN-7 components are mutagenic. These antibiotics inhibit the in vitro growth of L1210 cells (ED50 0.13 approximately 0.18 micrograms/ml). AN-7A, -7B and -7D also inhibit the growth of L1210 cells in mice.

The fermentation, isolation and characterization of a macromolecular peptide antibiotic: AN-1.

A new macromolecular peptide antibiotic, named AN-1, was isolated from the culture broth of Streptomyces albus AJ9003. From 18 liters of culture broth (110 units/ml activity) a 300 mg sample of AN-1 was obtained with a specific activity of 1,160 units/mg was obtained. AN-1 is a basic polypeptide with a molecular weight of 12,000, isoelectric point of pH 8.3, and gives a single band on SDS polyacrylamide gel electrophoresis. It is soluble in water but insoluble in ethanol, butanol and acetone. It was stable at pH 6 approximately 9 but very unstable at pH 2. The UV absorption spectrum shows a maximum at 280 nm. AN-1 had no antibacterial activity against the Gram-positive and Gram-negative bacteria tested, but shows strong inhibitory activity toward Escherichia coli MP2, a macromolecule permeable mutant. In addition to being highly mutagenic, AN-1 inhibits the in vitro cell growth of L1210 (ED50 0.41 micrograms/ml). However, AN-1 had no antitumor activity against mouse leukemia L1210 or Lewis lung carcinoma in mouse.

New streptothricin-group antibiotics, AN-201 I and II. Screening, fermentation, isolation, structure and biological activity.

Two streptothricin-group antibiotics, AN-201 I and II, were newly discovered and isolated from the culture broth of Streptomyces nojiriensis C-13. These antibiotics were purified by IRC-50 (H+) and CM-Sephadex C-50 chromatography, and paper electrophoresis. Structural analysis of AN-201 I and II showed that they were N beta-acetylated derivatives of streptothricin E and D, respectively. They had antibacterial activities against several strains of Escherichia coli, Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus, and showed a strong selective cytotoxic effect on 3T3 cells transformed with SV-40 as compared with their normal cells in a test system in vitro as well as in vivo.

New streptothricin-group antibiotics, AN-201 I, II and III. II. Chemical structures.

The new, belonging to the streptothricin-group antibiotics AN-201 I, II and III were found to be produced by a soil actinomycete identified as Streptomyces nojiriensis C-13. The chemical structures and the physical and spectroscopic properties of these compounds are reported here. On the basis of NMR and fast atom bombardment mass spectrometry (FAB-MS) spectra the antibiotics were identified as N beta-acetylated derivatives of streptothricins E, D and F.

The mechanism and change in the optic nerve head (ONH) circulation in rabbits after glucose loading.

PURPOSE: To assess the influence of the blood glucose level on ocular capillary circulation, we induced clinically significant hyperglycemia (200--300 mg/dl) in rabbits and investigated the changes in the optic nerve head (ONH) circulation. METHODS: Hyperglycemia was induced by injection of glucose (5.6 mmol/kg) into an auricular vein of healthy albino rabbits and changes in the ONH circulation were measured by the laser speckle method. In order to examine the role of nitric oxide (NO), glucose was administered after intravenous injection of an NO synthetase inhibitor (N(G)-nitro-L-arginine methyl ester, L-NAME, 1 mg/kg), then changes in the ONH circulation were measured. RESULTS: The blood glucose level reached a peak at 30 min after glucose loading and returned to its initial level by 2 hours. ONH circulation showed a 60% increase compared with its initial level at 15 min after glucose loading and subsequently remained almost unchanged throughout the 2-hour observation period. There were no significant changes of the blood pressure, heart rate, or intraocular pressure. The glucose-induced increase of ONH circulation was completely inhibited by pretreatment with L-NAME. CONCLUSIONS: ONH circulation was increased by administration of glucose to healthy rabbits. A high blood glucose level seems to promote ocular capillary circulation and NO as well as insulin appear to have a role in this process.

The effect of nipradilol, an alpha-beta blocker, on retinal blood flow in healthy volunteers.

PURPOSE: To study the effects of topically applied nipradilol, an alpha-beta blocker recently developed in Japan as an ocular hypotensive drug, on retinal blood flow (RBF) in healthy volunteers. METHODS: Seven healthy volunteers (mean age, 33 years) underwent measurement of RBF using a newly developed stabilized laser Doppler velocimetry system. In a double-blind trial, retinal arterial blood flow, intraocular pressure (IOP), and blood pressure (BP) were measured before and after the instillation of nipradilol or saline every hour for 5 hours. RESULTS: Retinal arterial blood flow and the diameter of the retinal artery significantly (p< 0.05) increased at 4 hours after instillation in nipradilol-treated eyes. Retinal blood velocity did not change significantly. Nipradilol evoked a significant (p< 0.05) bilateral decrease in IOP. Mean BP decreased significantly (p< 0.05) 3 hours after instillation. Ocular perfusion pressure (OPP), calculated from the mean BP and IOP, did not change significantly during the study. CONCLUSION: Topical nipradilol significantly increased retinal arterial blood flow in healthy volunteers, not through a secondary effect dependent on a change in OPP, but likely through the vasodilatory action of the drug.

Involvement of nitric oxide in the ocular hypotensive action of nipradilol.

PURPOSE: To evaluate the role of nitric oxide (NO) in the mechanism of the ocular hypotensive action of nipradilol, a beta-blocker with alpha( 1)-blocking activity. METHODS: Change in intraocular pressure (IOP) of albino rabbits was measured after a single application of carboxy-PTIO (c-PTIO), an NO trapping agent. Next, IOP change was measured every hour for 5 hours after the instillation of 0.25% nipradilol into one of the eyes with and without c-PTIO pretreatment of both eyes. IOP change induced by desnitro-nipradilol was also examined. The outflow facility and uveoscleral outflow were determined by two-level constant pressure and anterior chamber perfusion methods before and at 3 hours after the application of nipradilol with and without c-PTIO pretreatment. RESULTS: Topical administration of c-PTIO showed no significant effect on IOP. Unilateral instillation of nipradilol reduced IOP significantly compared with control eyes with a maximum reduction of 3.6 mmHg and effect duration of 3 hours. Pretreatment with c-PTIO partially inhibited the reduction during an earlier period (1 approximately 2 hours) and completely at 3 hours. IOP change by desnitro-nipradilol was similar to that by nipradilol with c-PTIO pretreatment. Nipradilol increased both outflow facility and uveoscleral outflow at 3 hours, whereas pretreatment with c-PTIO inhibited both of these outflows. CONCLUSIONS: Results indicate that ocular hypotensive action by nipradilol during the relatively late period may be mainly due to enhancement of aqueous humor outflow by NO at least in the rabbits.