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Biomedical subjects

Y Shiomi

Publications and source records attributed to Y Shiomi.

At least 19 recordsLinked to original sources
PubMed2001

A large outbreak of foodborne infection attributed to Providencia alcalifaciens.

The enteropathogenicity of Providencia alcalifaciens, a member of the family Enterobacteriaceae, has not yet been well established. In November 1996, a large outbreak of foodborne infection occurred in Fukui, Japan. In this study, the etiology of the outbreak was investigated. No other recognized enteropathogens were detected in patient fecal samples, but P. alcalifaciens was detected in 7 of 18 samples. The isolates were found to be clonal by pulsed-field gel electrophoresis. The patients who presented with gastroenteritis had elevated levels of specific antibody against the isolated P. alcalifaciens. The isolates showed invasion of Caco-2 cells and fluid accumulation in rabbit ileal loops. This study strongly suggests that the outbreak was caused by P. alcalifaciens. This is the first report of a large outbreak of foodborne infection attributed to the organism and provides definitive evidence that P. alcalifaciens is a causative agent of gastroenteritis.

Animals↗
PubMed2001

Atlantoaxial subluxation in an adult secondary to retropharyngeal abscess.

Atlantoaxial subluxation secondary to a retropharyngeal abscess is well described in children, but very rare in adults. Only two adult cases have been reported in the literature. We present a case of severe atlantoaxial subluxation in an adult secondary to retropharyngeal abscess. His atlas-dens interval was very large, up to 10 mm in flexion. We tried external fixation with a neck collar initially, but for remaining instability, surgical fusion was performed. The mechanism of subluxation is attributed to softening of the ligament allowing greater mobility at the joint. The etiology of this process is speculative.

Atlanto-Axial Joint↗
PubMed2001

Hearing impairment in a patient with unilateral narrowing of the internal auditory canal--a case report.

A 9-year-old boy complaining of left hearing loss with unknown date of onset visited our clinic. The pure tone audiogram showed profound hearing loss in the left ear, while normal in the right ear. Computed tomography and magnetic resonance imaging showed narrowing of the left internal auditory canal (IAC) in contrast with the right IAC. Distortion Product Otoacoustic Emissions of the left ear were not present above the background noise at any frequency tested in contrast to the right one. A retrocochlear lesion might be accompanied, while the profound hearing loss was thought to be caused mainly by a cochlear lesion.

Child↗
PubMed2001

CJ-15,801, a novel antibiotic from a fungus, Seimatosporium sp.

A novel antibiotic, CJ-15,801 (I), was isolated from the fermentation broth of a fungus, Seimatosporium sp. CL28611. The structure was determined to be a pantothenic acid analog having an alpha,beta-unsaturated carboxylic acid moiety by spectroscopic analyses. The compound inhibits the growth of multi-drug resistant (MDR) Staphylococcus aureus strains with MIC ranging from 6.25 to 50 microg/ml.

Anti-Bacterial Agents↗
PubMed2001

Cytokine production inhibitors produced by a fungus, Oidiodendron griseum.

A series of diterpenes were isolated from the fermentation broth of a fungus, Oidiodendron griseum CL37215. The diterpenes were identified as LL-Z1271alpha, LL-Z1271gamma, CJ-14,445, PR 1388, CJ-14,604 and a new diterpene, CJ-14,515. They inhibited both lipopolysaccharide-induced interleukin-1beta and tumor necrosis factor-alpha production in human whole blood with IC50s of the range from 0.049 to 100 microM.

Ascomycota↗
PubMed2001

Novel cytokine production inhibitors produced by a basidiomycete, Marasmiellus sp.

New cytokine production inhibitors, CJ-14,877 (I) and CJ-14,897 (II), were isolated from the fermentation broth of a basidiomycete, Marasmiellus sp. CL21624. Their structures were determined to be methyl-(7S,8S)-5-(7,8-dihydroxypropyl)pyridine-2-carboxylate and methyl-(7S,8S)-5-(8-acetoxy-7-hydroxypropyl)pyridine-2-carboxylate [corrected], respectively, by spectroscopic analyses. These compounds showed inhibitory activities for lipopolysaccharide-induced production of interleukin-1beta and tumor necrosis factor-alpha in human whole blood with IC50 values of the range from 0.059 to 2.6 microM.

Agaricales↗
PubMed2001

New pyrrolizidinone antibiotics CJ-16,264 and CJ-16,367.

Two new antibiotics, CJ-16,264 (I) and CJ-16,367 (II), were isolated from the fermentation broth of an unidentified fungus CL39457. These antibiotics have a pyrrolizidinone skeleton, first discovered in fungi. Compounds I and II inhibit the growth of Gram-positive multi-drug resistant bacteria and some Gram-negative strains such as Moraxella catarrhalis and Escherichia coli with altered permeability (imp). Comparison of an antibacterial profile between the two compounds suggested that the gamma-lactone portion of I is important for the activity.

Anti-Bacterial Agents↗
PubMed2000

ATP-dependent structural change of the eukaryotic clamp-loader protein, replication factor C.

The eukaryotic DNA sliding clamp that keeps DNA polymerase engaged at a replication fork, called proliferating cell nuclear antigen (PCNA), is loaded onto the 3' ends of primer DNA through its interaction with a heteropentameric protein complex called replication factor C (RFC). The ATPase activity of RFC is necessary for formation of a functional PCNA clamp. In the present study, the sensitivity of RFC to partial proteolysis is used to show that addition of ATP, ATPgammaS, or ADP induces different structural changes in RFC. Direct observation by electron microscopy reveals that RFC has a closed two-finger structure called the U form in the absence of ATP. This is converted into a more open C form on addition of ATP. In contrast, the structural changes induced by ATPgammaS or ADP are limited. These results suggest that RFC adapts on opened configuration intermediately after ATP hydrolysis. We further observe that PCNA is held between the two fingers of RFC and propose that the RFC structure change we observe during ATP hydrolysis causes the attached PCNA to form its active ring-like clamp on DNA.

Adenosine Triphosphate↗
PubMed2000

Fucogalactan isolated from Sarcodon aspratus elicits release of tumor necrosis factor-alpha and nitric oxide from murine macrophages.

Eight species of mushrooms were evaluated for mitogenic activity by the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method using spleen cells of C3H/HeN female mice. The hot water-soluble (HWS) fraction extracted from Sarcodon aspratus showed the highest activity. The mitogen in Sa. aspratus was isolated by Sepharose 6B and DEAE-Sepharose CL-6B column chromatography. Preliminary structural analyses indicated that the mitogen was a fucogalactan. Fucogalactan elicited the release of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) in macrophages of mice in vitro. TNF-alpha production induced with 50 microg/ml of fucogalactan was significantly higher than that induced by lentinan (500 microg/ml) by approximately 4.3-fold. Also, fucogalactan showed dose dependence at concentrations from 5 to 500 microg/ml in NO production. Thus, fucogalactan does elicit the release of cytokines such as TNF-alpha and NO.

Adjuvants, Immunologic↗
PubMed2000

Atomic force microscopy with carbon nanotube probe resolves the subunit organization of protein complexes.

Among many scanning probe microscopies, atomic force microscopy (AFM) is a useful technique to analyse the structure of biological materials because of its applicability to non-conductors in physiological conditions with high resolution. However, the resolution has been limited to an inherent property of the technique; tip effect associated with a large radius of the scanning probe. To overcome this problem, we developed a carbon nanotube probe by attaching a carbon nanotube to a conventional scanning probe under a well-controlled process. Because of the constant and small radius of the tip (2.5-10 nm) and the high aspect ratio (1:100) of the carbon nanotube, the lateral resolution has been much improved judging from the apparent widths of DNA and nucleosomes. The carbon nanotube probes also possessed a higher durability than the conventional probes. We further evaluated the quality of carbon nanotube probes by three parameters to find out the best condition for AFM imaging: the angle to the tip axis; the length; and the tight fixation to the conventional tip. These carbon nanotube probes, with high vertical resolution, enabled us to clearly visualize the subunit organization of multi-subunit proteins and to propose structural models for proliferating cell nuclear antigen and replication factor C. This success in the application of carbon nanotube probes provides the current AFM technology with an additional power for the analyses of the detailed structure of biological materials and the relationship between the structure and function of proteins.

Carbon↗
PubMed2000

Mechanisms of chloride secretion induced by thermostable direct haemolysin of Vibrio parahaemolyticus in human colonic tissue and a human intestinal epithelial cell line.

Thermostable direct haemolysin (TDH) produced by Vibrio parahaemolyticus is thought to play an important role in the severe diarrhoea caused by this organism. This study investigated the enterotoxicity of TDH for human intestinal cells. Addition of TDH to the mucosal side of human colonic tissue in Ussing chambers caused increased short circuit currents (Isc), a process that was inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS), an inhibitor of Ca2+ -activated chloride (Cl-) channels. With human colonic epithelial (Caco-2) cells, high Isc and intracellular Ca2+ concentrations ([Ca2+]in) were detected after the addition of TDH to the apical side of the cell monolayer. The Isc decreased with the addition of DIDS, but not with glybenclamide, 5-nitro-2-(3-phenylpropylamino) benzoic acid, or gadolinium chloride. No Isc increase with TDH was observed when the Cl- in the medium was replaced by gluconate or when Ca2+ was depleted. Similarly, TDH did not raise [Ca2+]in after depletion of extracellular Ca2+. R7, a mutant form of TDH, reduced the effects of TDH on Isc and [Ca2+]in, as did protein kinase C (PKC) inhibitors. Thus, TDH increases Cl- secretion in human colonic epithelial cells, apparently through mechanisms involving cell binding and Ca2+ influx, followed by elevation of [Ca2+]in associated with PKC phosphorylation.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1999

Correlation between rCBF and speech perception in cochlear implant users.

OBJECTIVE: Although cochlear implants (CIs) have provided the opportunity for bilaterally deaf individuals to recover their hearing abilities, the speech perception performances of the CI users varies considerably. To elucidate the cortical mechanisms of processing speech signals coded by CIs, we evaluated the correlation between the brain activity during speech activation and speech perception in CI users by PET. METHODS: Fourteen postlingually deaf CI users were examined. CI used in the patients was a 22-channel system and its speech-coding strategy was the Nucleus spectral peak (SPEAK) strategy. To evaluate the speech perception performances, we examined vowel perception, consonant perception and speech tracking performances in the Japanese language. Regional cerebral blood flow (rCBF) was measured during no sound stimulation and speech sound stimulation. PET data of the silent condition was subtracted from that of speech stimulation to determine changes in rCBF. In the search for changes in rCBF in the areas for auditory processing, three regions of interest (ROI) were selected; primary auditory area, auditory association area and Broca's area. The correlation between the rCBF changes in the ROIs and the speech perception performances was analyzed using Pearson's correlation coefficient. RESULTS: The patient's speech perception performances ranged widely. Although there were no significant correlations between the speech perception and the rCBF increases in the primary auditory area and Broca's area, there were positive correlations in the auditory association area. In the left auditory association area, the correlation coefficient of the vowel perception performance was 0.546 (P <0.05) and that of the speech-tracking test was 0.657 (P < 0.05). Regarding the consonant perception performance, the correlation coefficient was 0.743 (P < 0.01). There was a positive correlation only between the consonant perception performance and the rCBF increase (R = 0.576, P < 0.05) in the right auditory association area. These correlations are stronger in the left hemisphere than in the right hemisphere. CONCLUSIONS: It is suggested that the improvement of the auditory processing of speech in CI users with SPEAK strategy is accompanied by the recruitment of more neurons in the auditory association areas. The adult auditory cortices may still have plasticity or

Adult↗
PubMed1999

Cochlear implant in patients with residual hearing.

OBJECTIVE: The postoperative speech perception abilities of severely hearing-impaired patients with multi-channel cochlear implant were compared with preoperative speech perception performance with conventional hearing aids. METHODS: Cochlear implantation was performed in six severely to profoundly hearing-impaired patients. They had unaided pure-tone thresholds of 70-100-dB HL and aided thresholds of 35-90-dB HL in the better ear, but were not able to perceive speech sounds well with hearing aids. RESULTS: Postoperatively, all the patients had significantly improved speech perception performance, exceeded the average skills of profoundly deaf cochlear implant users, and were able to communicate without writing. CONCLUSION: These results imply that cochlear implant may be indicated for severely to profoundly deaf subjects, if they receive little or no benefit from conventional hearing aids.

Adult↗
PubMed1999

Comparison of bacterial community structures in the rhizoplane of tomato plants grown in soils suppressive and conducive towards bacterial wilt.

It has been reported that the growth of Ralstonia solanacearum is suppressed at the rhizoplane of tomato plants and that tomato bacterial wilt is suppressed in plants grown in a soil (Mutsumi) in Japan. To evaluate the biological factors contributing to the suppressiveness of the soil in three treated Mutsumi soils (chloroform fumigated soil; autoclaved soil mixed with intact Mutsumi soil; and autoclaved soil mixed with intact, wilt-conducive Yamadai soil) infested with R. solanacearum, we bioassayed soil samples for tomato bacterial wilt. Chloroform fumigation increased the extent of wilt disease. More of the tomato plant samples wilted when mixed with Yamadai soil than when mixed with Mutsumi soil. Consequently, the results indicate that the naturally existing population of microorganisms in Mutsumi soil was significantly able to reduce the severity of bacterial wilt of tomato plants. To characterize the types of bacteria present at the rhizoplane, we isolated rhizoplane bacteria and classified them into 22 groups by comparing their 16S restriction fragment length polymorphism patterns. In Yamadai soil a single group of bacteria was extremely predominant (73.1%), whereas in Mutsumi soil the distribution of the bacterial groups was much more even. The 16S rDNA sequence analysis of strains of dominant groups suggested that gram-negative bacteria close to the beta-proteobacteria were most common at the rhizoplane of the tomato plants. During in vitro assays, rhizoplane bacteria in Mutsumi soil grew more vigorously on pectin, one of the main root exudates of tomato, compared with those in Yamadai soil. Our results imply that it is difficult for the pathogen to dominate in a diversified rhizobacterial community that thrives on pectin.

Bacteria↗
PubMed1998

Influence of unilateral deafness on auditory evoked magnetic field.

To investigate the effect of unilateral deafness on central auditory mechanisms, we examined patients with unilateral deafness of various durations. Auditory evoked magnetic fields (AEF) were recorded using a whole-head neuromagnetometer. In patients who had unilateral deafness for more than 3 weeks, the average N100m latency in the ipsilateral hemisphere did not differ from that in the contralateral hemisphere. In addition, in some patients with congenital or early onset deafness, the equivalent current dipole (ECD) moment was larger in the ipsilateral hemisphere than in the contralateral hemisphere. These findings suggest that unilateral deafness may cause reorganization of the central auditory pathway. They also suggest that central auditory pathway in adults has some plasticity, though not as much as in childhood.

Adult↗
PubMed1997

Characteristics of DPOAE audiogram in tinnitus patients.

To investigate cochlear activity in tinnitus, the DPOAE (distortion product otoacoustic emission) audiograms (DP-gram) of tinnitus patients were measured. Nine tinnitus patients (15 ears) with normal hearing and 55 tinnitus patients (75 ears) with hearing impairment were included in this study. Significant decreases in DPOAE amplitude over a limited frequency range were observed in 93.3% of the normal hearing tinnitus group and in 96% of the hearing-impaired tinnitus group. The averaged DP-gram of the normal hearing tinnitus group was significantly different from that of the normal subject (repeated-measures ANOVA, P < 0.01). These results imply that tinnitus may be evaluated objectively by DPOAE.

Adult↗