Search

A transport system for branched-chain amino acids (designated as LIV-II system) in Pseudomonas aeruginosa requires Na+ for its operation. Coupling cation for this system was identified by measuring cation movement during substrate entry using cation-selective electrodes. Uptakes of Na+ and Li+ were induced by the imposition of an inwardly-directed concentration gradient of leucine, isoleucine, or valine. No uptake of H+ was found, however, under the same conditions. In addition, effects of Na+ and Li+ on the kinetic property of the system were examined. At chloride salt concentration of 2.5 mM, values of apparent Km and Vmax for leucine uptake were larger in the presence of Na+ than Li+. These results indicate that the LIV-II transport system is a Na+(Li+)/substrate cotransport system, although effects of Na+ and Li+ on kinetics of the system are different. [ABSTRACT FROM AUTHOR]

Ultrasound can deliver speech information when it is amplitude-modulated with speech and presented via bone conduction. This speech-modulated bone-conducted ultrasound (SM-BCU) can also transmit prosodic information. However, there is insufficient research on the recognition of vowel duration in SM-BCU. The aim of this study was to investigate the categorization of vowel durational changes in SM-BCU using a behavioral test. Eight Japanese-speaking participants with normal hearing participated in a forced-choice behavioral task to discriminate between "hato" (pigeon) and "haato" (heart). Speech signal stimuli were presented in seven duration grades from 220 ms to 340 ms. The threshold at which 50% of responses were "haato" was calculated and compared for air-conducted audible sound (ACAS) and SM-BCU. The boundary width was also evaluated. Although the SM-BCU threshold (mean: 274.6 ms) was significantly longer than the ACAS threshold (mean: 269.6 ms), there were no differences in boundary width. These results suggest that SM-BCU can deliver prosodic information about vowel duration with a similar difference limen to that of ACAS in normal hearing.

Objectives: Hearing loss is a serious problem in infants and children because it may interfere with the development of typical speech, verbal language, and auditory and communication skills. By measuring hearing ability (thresholds) as early as possible, even as early as during infancy, effective treatment can be administered. These treatments may significantly reduce the handicap associated with hearing loss. However, at times during behavioral auditory tests, observers cannot determine whether or not an accurate threshold was obtained. To support the use of infant audiometry for accurate diagnosis, audiologic behavioral responses may be obtained by selecting stimuli that interest infants, e.g., their mothers' voices., Methods: We evaluated 30 infants who were presented to our hospital for behavioral auditory assessment in 2016. The infants' ages ranged from 4 months to 3 years and 6 months. The mean age was 1 year and 10 months ±10 months (±standard deviation). The infants' hearing thresholds for their mothers' voices and warble tones at 250-4000 Hz were measured. Auditory brainstem response (ABR) had already been evaluated in 24 infants. Relationships between mother's voice and warble tone or ABR thresholds as well as responses to the initial stimuli and stimuli at the threshold were investigated. These responses were classified into four grades (no response, uncertain response, possible positive response, and positive response), and the response to mother's voice and warble tone were subsequently compared., Results: Mother's voice thresholds significantly correlated with all warble tone thresholds. In the relationship between the mother's voice threshold and average hearing levels of 500, 1000, and 2000 Hz, two infants were outliers. In these infants, the average hearing levels were relatively higher than the mother's voice thresholds. Judging from their ABR thresholds, the mother's voice thresholds were valid and the average hearing levels were worse than their original assessed hearing ability. The responses to mothers' voices were more distinct than those to warble tones, both for initial stimuli presentation and the determined threshold., Conclusions: Audiologic behavioral responses to mothers' voices were clearer than those for warble tones. Evaluations that use the mother's voice threshold are useful for estimating hearing levels in infants., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Bone-conducted ultrasound (BCU) can be heard for both normal-hearing and some profoundly deaf individuals. Moreover, amplitude-modulated BCU can transmit the speech signal. These characteristics of BCU provide the possibility of the developing a bone-conducted ultrasonic hearing aid. Previous studies on the perception mechanism of speech-modulated BCU have pointed to the importance of temporal rather than frequency information. In order to elucidate the perception of speech-modulated BCU, further investigation is need concerning the processing of temporal information. The temporal processing of air-conducted audible sounds (ACASs) involves the integration of closely presented sounds into a single information unit. The long-temporal window of integration was estimated approximately 150-200 ms, which contribute to the discrimination of speech sound. The present study investigated the long-temporal integration system for BCU evaluated by stimulus omission using magnetoencephalography. Eight participants with normal hearing took part in this study. Ultrasonic tone burst with the duration of 50 ms and frequency of 30 kHz was used as the standard stimulus and presented with steady onset-to-onset times or stimulus-onset asynchronies (SOAs). In each sequence, the duration of the SOAs were set to 100, 125, 150, 175, 200, or 350 ms. For deviant, tones were randomly omitted from the stimulus train. Definite mismatch fields were elicited by sound omission in the stimulus train with an SOA of 100-150 ms, but weren't with an SOA of 200 and 350 ms for all participants. We found that stimulus train for BCUs can be integrated within a temporal window of integration with an SOA of 100-150 ms, but are regarded as a separate event when the SOA is 200 or 350 ms in duration. Therefore, we demonstrated that the long-temporal window of integration for BCUs estimated by omission was 150-200 ms, which was similar to that for ACAS (Yabe et al. NeuroReport 8 (1997) 1971-1974 and Psychophysiology. 35 (1998) 615-619). These findings contribute to the elucidation and improvement of the perception of speech-modulated BCU., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Discovery of novel phases and their associated transitions in low-dimensional nanoscale systems is of central interest as the origin of emergent phenomena and new device paradigms. Although typical ferroelectrics such as PbTiO 3 exhibit diverse phase transition sequences, the conventional incompatible mechanisms of ferroelectricity and magnetism keep them as simply nonmagnetic phases, despite the immense practical prospective of multiferroics in novel functional devices. Here, we demonstrate using density function theory that PbTiO 3 nanodots exhibit unconventional multiferroic phase transitions. The nanosize and nonstoichiometric effects intrinsic to nanodots bring about the coexistence of ferromagnetism with the host electric polarization, mediated by the termination and surface morphology. We also predict the key features of the size-dependent phase diagram of nanodots that involve a rich sequence of ferroelectric-multiferroic-ferromagnetic/nonmagnetic (FE-MF-FM/NM) multiferroic phase transitions. The present work thus provides an avenue to realizing multiferroics and multifunctional oxides in low-dimensional systems.

Unconventional phases and their transitions in nanoscale systems are recognized as an intriguing avenue for both unique physical properties and novel technological paradigms. Although the multiferroic phase has attracted considerable attention due to the coexistence and cross-coupling of electric and magnetic order parameters, mutually exclusive mechanism between ferroelectricity and ferromagnetism leaves conventional ferroelectrics such as PbTiO 3 simply nonmagnetic. Here, we demonstrate from first-principles that ultrathin PbTiO 3 nanowires exhibit unconventional multiferroic phases with emerging ferromagnetism and coexisting ferroelectric/ferrotoroidic ordering. Nanometer-scale and nonstoichiometric effects intrinsic to the nanowires bring about nonzero and nontrivial magnetic moments that coexist with the host ferroelectricity. The multiferroic order is susceptible to surface termination and nanowire morphology. Furthermore, calculations suggest that the nanowires undergo size-dependent ferroelectric-multiferroic-ferromagnetic phase transitions. This work therefore provides a route to multiferroic transitions in conventional nonmagnetic ferroelectric oxides.

Ultimately thin multiferroics arouse remarkable interest, motivated by the diverse utility of coexisting ferroelectric and (anti)ferromagnetic order parameters for novel functional device paradigms. However, the ferroic order is inevitably destroyed below a critical size of several nanometers. Here, we demonstrate a new path toward realization of atomically thin multiferroic monolayers while resolving a controversial origin for unexpected "dilute ferromagnetism" emerged in nanocrystals of nonmagnetic ferroelectrics PbTiO3. The state-of-the-art hybrid functional of Hartree-Fock and density functional theories successfully identifies the origin and underlying physics; oxygen vacancies interacting with grain boundaries (GBs) bring about (anti)ferromagnetism with localized spin moments at the neighboring Ti atoms. This is due to spin-polarized defect states with broken orbital symmetries at GBs. In addition, the energetics of oxygen vacancies indicates their self-assembling nature at GBs resulting in considerably high concentration, which convert the oxygen-deficient GBs into multiferroic monolayers due to their atomically thin interfacial structure. This synthetic concept that realizes multiferroic and multifunctional oxides in a monolayered geometry through the self-assembly of atomic defects and grain boundary engineering opens a new avenue for promising paradigms of novel functional devices.

Speech-modulated bone-conducted ultrasound (BCU) can transmit speech sounds for some profoundly deaf individuals. Hearing aids using BCU are considered to be a novel hearing system for such individuals. In our previous study, the speech discrimination for speech-modulated BCU was objectively confirmed using a magnetoencephalography. Moreover, in our previous behavioral study, prosodic information for speech-modulated BCU could also be discriminated in the normal hearing. However, the prosodic discrimination for speech-modulated BCU has not objectively been studied. In order to evaluate the prosodic discrimination for speech-modulated BCU, mismatch fields (MMFs) elicited by prosodic and segmental change were measured for speech-modulated BCU and air-conducted speech. Ten Japanese participants with normal hearing took part in this study. Stimuli re-synthesized from the speech of a native Japanese female adult were used. Standard stimulus was /itta/ with a flat pitch pattern, and two deviant stimuli were /itta?/ with a rising pitch pattern and /itte/ with a flat pitch pattern. All and nine participants elicited the prominent MMF elicited by the prosodic and segmental change for the speech-modulated BCU, respectively. The moment of MMF components for speech-modulated BCU was significantly smaller than those for air-conducted speech, while no difference in the MMF latency elicited by the prosodic and segmental change were observed between both stimulus conditions. Comparing the MMFs elicited by prosodic and segmental change, no significant differences were observed for both stimulus conditions. Thus, it is suggested that the prosodic change can be discriminate to the same degree as segmental change even for speech-modulated BCU. However, discrimination capability for speech-modulated BCU is slightly inferior to that for air-conducted speech., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

When two tones are presented in a short interval of time, the presentation of the preceding tone (masker) suppresses the response evoked by the subsequent tone (signal). To address the processing in forward suppression, we applied 2- and 4-kHz maskers, followed by a 1-kHz signal at varying signal delays (0 to 320 ms) and measured the signal-evoked N1m. A two-way analysis of variance revealed a statistically significant effect for signal delay in both masker presentation conditions. The N1m peak amplitude at the signal delay of 320 ms was significantly larger than those of 10, 20, 40, and 80 ms (p < 0.05). No significant enhancement for the very short signal delay was observed. The results suggest that the enhancement of N1m peak amplitude for short signal delay conditions is maximized when the frequency of the masker is identical to that of the signal.

When two tones are presented in a short time interval, the response to the second tone is suppressed. This phenomenon is referred to as forward suppression. To address the effect of the masker laterality on forward suppression, magnetoencephalographic responses were investigated for eight subjects with normal hearing when the preceding maskers were presented ipsilaterally, contralaterally, and binaurally. We employed three masker intensity conditions: the ipsilateral-strong, left-right-balanced, and contralateral-strong conditions. Regarding the responses to the maskers without signal, the N1m amplitude evoked by the left and binaural maskers was significantly larger than that evoked by the right masker for the left-strong and left-right-balanced conditions. No significant difference was observed for the right-strong condition. Regarding the subsequent N1m amplitudes, they were attenuated by the presence of the left, binaural, and right maskers for all conditions. For the left- and right-strong conditions, the subsequent N1m amplitude in the presence of the left masker was smaller than those of the binaural and right maskers. No difference was observed between the binaural and right masker presentation. For left-right-balanced condition, the subsequent N1m amplitude decreased in the presence of the right, binaural, and left maskers in that order. If the preceding activity reflected the ability to suppress the subsequent activity, the forward suppression by the left masker would be superior to that by the right masker for the left-strong and left-right-balanced conditions. Furthermore, the forward suppression by the binaural masker would be expected to be superior to that by the left masker owing to additional afferent activity from the right ear. Thus, the current results suggest that the forward suppression by ipsilateral maskers is superior to that by contralateral maskers although both maskers evoked the N1m amplitudes to the same degree. Additional masker at the contralateral ear can attenuate the forward suppression by the ipsilateral masker.

Ultrasound can be perceived by bone conduction, and its characteristics differ from those of air-conducted audible sound (ACAS) in some respects. Despite many studies on ultrasonic hearing, the details have not yet been clarified. In this study, to elucidate the perception mechanism, the masking of bone-conducted ultrasound (BCU) produced by ACAS and the sensitivity of BCU in hearing impaired subjects were evaluated. We found that BCU was masked by high frequency ACAS, especially in the frequency range of 10-14 kHz. The most effective masker frequency depended on masker intensity. For hearing impaired subjects, the pure tone thresholds at 1-8 kHz and the maximum audible frequencies at cut-off intensities of 70-100 dB HL were significantly associated with the BCU threshold (p < 0.01 or p < 0.05). No subjects with estimated total loss of the inner hair cell system in the cochlear basal turn could hear BCU. These results suggest the peripheral perceptual region to be located in the cochlea. The results of masking show the faster excitation spread to the lower frequency range, depending on the intensity. This faster excitation spread may be due to nonlinearity in cochlear mechanics, which may work even without cochlear amplifier, and induce unique characteristics of BCU., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Bone-conducted ultrasound (BCU) modulated by speech sound is recognized as speech sound and activates the auditory cortex similar to audible sound. To investigate the mechanisms of perception, the effects of stimulus duration on N1m were compared among air-conducted audible speech sound (AC speech), AC speech with carrier BCU and speech-modulated BCU in eight native Japanese with normal hearing. The Japanese vowel sound /a/ was used as a stimulus with durations of 10, 15, 20, 30, 40 and 60 ms. Comparison between AC speech with and without carrier showed that the presentation of carrier had no effect on N1m evoked by AC speech. Comparison among the three conditions showed that N1m amplitude for speech-modulated BCU differed from that for the two AC speeches. Moreover, N1m amplitude growth saturated at 40 ms for speech-modulated BCU, and at 20 ms for two AC speeches. These results suggest a difference in temporal integration of N1m between speech-modulated BCU and AC speech. Considering these results, it is reasonable to conclude that N1m evoked by speech-modulated BCU is influenced mainly by the ultrasonic component rather than demodulated audible sound. Given this finding, the notion needs to be considered that the mechanisms underlying perception and recognition of speech-modulated BCU depend on the ultrasonic component to some extent., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Latexin, a protein possessing inhibitory activity against rat carboxypeptidase A1 (CPA1) and CPA2, is expressed in a neuronal subset in the cerebral cortex and cells in other neural and non-neural tissues of rat. Although latexin also inhibits mast-cell CPA (MCCPA), the expression of latexin in rat mast cells has not previously been confirmed. In the present study we examined the expression and subcellular localization of latexin in rat peritoneal mast cells. Western blot and reverse-transcriptase-mediated PCR analyses showed that latexin was contained and expressed in the rat peritoneal mast cells. Immunocytochemically, latexin immunofluorescence was localized on granular structures distinct from MCCPA-, histamine- or cathepsin D-immunopositive granules. Immunoelectron microscopy revealed that latexin was associated with a minority population of granules. The latexin-associated granules were separated from MCCPA- or histamine-containing granules on a self-generating density gradient of polyvinylpyrrolidone-coated silica-gel particles (Percoll). Treatments with high ionic strength and heparinase released latexin from the granules, suggesting that latexin is non-covalently associated with a heparin-like component of the granules. MCCPA and histamine were released from the mast cells after non-immunological and immunological stimulation with compound 48/80, A23187 and anti-IgE antibody, whereas latexin was not released. These results show that latexin is synthesized in rat peritoneal mast cells and suggest that it is associated with a unique type of intracellular granules distinct from MCCPA- and histamine-containing secretory granules and lysosomes.

For functional reconstitution of bacterial cotransporters (carriers or permeases) including the sodium-coupled branched-chain amino acid carrier (LIV-II carrier) of Pseudomonas aeruginosa, the presence of phospholipid is required through the process of solubilization and purification of the transporters from the bacterial membranes, suggesting the possibility that phospholipid may stabilize the structure of the cotransporter proteins to be in a functional form. In this study, this possibility was examined by studying the effect of denaturant on the secondary structure of the LIV-II carrier purified in the absence and presence of phospholipid using circular dichroism (CD) spectroscopy. CD spectra of the purified LIV-II carrier solubilized in n-octyl-beta-D-glucopyranoside (OG), OG/dioleoylphosphatidylethanolamine (DOPE)/dioleoylphosphatidylglycerol (DOPG) mixture, and dispersed into DOPE/DOPG small unilamellar vesicles were measured in the absence of denaturant. The three spectra were very similar and had a trough at 222 nm with mean residue molar ellipticity of -23000 deg.cm(2)/dmol and a shoulder at 208 nm. CD spectral analyses with three different methods (S.W. Provencher, J. Glöckner, Estimation of globular protein secondary structure from circular dichroism, Biochemistry 20 (1981) 33-37; J.Y. Yang, C.-S.C. Wu, H.Z. Martinez, Calculation of protein conformation from circular dichroism, Methods Enzymol. 130 (1986) 208-269; N. Sreerama, R.W. Woody, A self-consistent method for the analysis of protein secondary structure from circular dichroism, Anal. Biochem. 209 (1993) 32-44) revealed that the LIV-II carrier solubilized in OG/DOPE/DOPG mixture contained 69-75% alpha-helix and 0-9% beta-sheet. Addition of 6 M guanidine hydrochloride decreased 48% of the amplitude at 222 nm of the CD spectrum of the carrier solubilized in OG alone and 9-14% of the CD amplitude of the carrier solubilized in OG/DOPE/DOPG or OG/dioleoylphosphatidylcholine mixture and dispersed in liposomes composed of DOPE/DOPG. These results show that the ordered secondary structure of the LIV-II carrier is partially unfolded in OG without phospholipid by denaturant but is greatly stabilized with phospholipids with oleoyl chains independently of their polar head group composition and suggest that the alpha-helical structure of the carrier is mainly embedded in the lipid environment.

The monoclonal antibody (mAb) PC3.1 recognizes a subset of neurons distributed in the infragranular layers of the lateral neocortex of the rat. Immunoaffinity chromatography with mAb PC3.1 showed that this antibody specifically binds a peptide epitope on a 29 kDa protein named latexin. To study the molecular details of the protein, we isolated four independent cDNA clones for latexin from cDNA libraries of the rat cerebral cortex and whole brain using the amino acid sequences of latexin fragments. Analysis of these cDNA clones showed that the predicted primary structure of latexin consists of 223 amino acids, and has no strict homology to any sequences so far known. Western and Northern blots demonstrated that the latexin and its mRNA were expressed predominantly in neural tissues with some expression in non-neural tissues. The gene that encodes latexin in the rat appeared to have homologues in other mammalian species and in the chick. In situ hybridization showed that latexin mRNA is synthesized in a subset of neurons in the lateral but not the dorsal neocortex, and that the distribution profile of these neurons is quite similar to that of neurons expressing latexin. These results indicate that latexin is a novel class of neuronal protein which represents intracortical regionality, and suggest that the regional specification of the neocortex involves selective parcellation of neurons which express a particular gene.

The gene braB, encoding the Na(+)-coupled carrier for branched-chain amino acids in Pseudomonas aeruginosa PAO, was cloned on cosmid pMMB34. The cosmid clones carrying the braB gene were identified as those that restored growth at low leucine concentration and Na(+)-dependent leucine transport activity to P. aeruginosa PAO3536 defective in the transport of branched-chain amino acids. Determination of the nucleotide sequence of the DNA fragment shows that the braB gene comprises 1311 bp and encodes a hydrophobic protein of 437 amino acids with a calculated Mr of 45,279. The hydropathy profile suggests that there exist in the carrier protein 12 hydrophobic segments long enough to traverse the membrane. The amino acid sequence shows a high degree of homology with the brnQ product, a branched-chain amino acid carrier of Salmonella typhimurium, while no homology in the nucleotide sequences is found in the braB and brnQ genes.

Pyocin R1, a bacteriocin of Pseudomonas aeruginosa, is a protein particle shaped like a bacteriophage tail composed of a contractile sheath, core, baseplate and tail fibers. Alkaline treatment with sodium carbonate caused sheath contraction without considerable disassembly of other components. Circular dichroism (CD) spectra of pyocin R1 before and after the treatment, and of isolated sheath, were measured in wavelength regions around 220 and 290 nm at neutral pH. The alkaline treatment caused a red shift of the minimum from 208 nm to 212 nm. A marked difference in the CD spectrum was found in the near-ultraviolet region. THe difference is considered to be mainly due to a CD spectra change of tryptophan residues in the sheath subunits.

Antithrombin III (AT III) with defective biological functions and altered antigenicity has been found in a thrombophilic patient. Circular dichroism (CD) spectra of antithrombin III purified from the patient's plasma were measured in near and far-ultraviolet (UV) wavelength regions. The far-UV CD spectrum of the patient's AT III was similar at room temperature to that of normal AT III derived from healthy adult males. Mean residue ellipticity at 221 nm of the patient's AT III, however, decreased its magnitude by 6% gradually as temperature increased up to 74 degrees C, whereas that of the normal AT III reduced its magnitude sharply at around 63-64 degrees C and by 18%. The near-UV CD spectrum of patient's AT III was different from that of normal AT III. These results indicate that the secondary structure of patient's AT III is similar to that of normal AT III at room temperature, while local conformation of aromatic amino acid residues in the abnormal protein is different from that in the normal one and that the secondary structure of the patient's AT III is heat-stable, while that of the normal one is heat-labile.

Additon of pyocin R1, a bacteriocin of Pseudomonas aeruginosa, to sensitive cells caused a fluorescence increase of 8-anilino-1-naphthalenesulfonate (ANS) in the cell suspension. The reaction was rapid, starting with a short time lag after adsorption of pyocin onto the cells and finishing within several minutes. The fluorescence response was attributed to the interaction of the cell body and ANS, not to that of the medium outside the cells and ANS. The maximal amplitude of fluorescence after pyocin addition was dependent on temperature, and the relation appeared to be biphasic. Similarly, Arrhenius plots of the initial rate of fluorescence change were biphasic. The transition of slopes in both cases occurred in the temperature range between 18 and 19 degrees. These results suggest that ANS interacts with lipids in the cell envelope and that pyocin causes a structural change of the cell envelope leading to increased fluorescence of ANS.