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Biomedical subjects

Atsushi Yokota

Publications and source records attributed to Atsushi Yokota.

At least 19 recordsLinked to original sources
PubMed2006

Population dynamics of Bifidobacterium species in human feces during raffinose administration monitored by fluorescence in situ hybridization-flow cytometry.

The population dynamics of bifidobacteria in human feces during raffinose administration were investigated at the species level by using fluorescence in situ hybridization (FISH) coupled with flow cytometry (FCM) analysis. Although double-staining FISH-FCM using both fluorescein isothiocyanate (FITC) and indodicarbocyanine (Cy5) as labeling dyes for fecal samples has been reported, the analysis was interfered with by strong autofluorescence at the FITC fluorescence region because of the presence of autofluorescence particles/debris in the fecal samples. We circumvented this problem by using only Cy5 fluorescent dye in the FISH-FCM analysis. Thirteen subjects received 2 g of raffinose twice a day for 4 weeks. Fecal samples were collected, and the bifidobacterial populations were monitored using the established FISH-FCM method. The results showed an increase in bifidobacteria from about 12.5% of total bacteria in the prefeeding period to about 28.7 and 37.2% after the 2-week and 4-week feeding periods, respectively. Bifidobacterium adolescentis, the Bifidobacterium catenulatum group, and Bifidobacterium longum were the major species, in that order, at the prefeeding period, and these bacteria were found to increase nearly in parallel during the raffinose administration. During the feeding periods, indigenous bifidobacterial populations became more diverse, such that minor species in human adults, such as Bifidobacterium breve, Bifidobacterium bifidum, Bifidobacterium dentium, and Bifidobacterium angulatum, proliferated. Four weeks after raffinose administration was stopped, the proportion of each major bifidobacterial species, as well as that of total bifidobacteria, returned to approximately the original values for the prefeeding period, whereas that of each minor species appeared to differ considerably from its original value. To the best of our knowledge, these results provide the first clear demonstration of the population dynamics of indigenous bifidobacteria at the species level in response to raffinose administration.

Adult↗
PubMed2006

Modulation of rat cecal microbiota by administration of raffinose and encapsulated Bifidobacterium breve.

To investigate the effects of administration of raffinose and encapsulated Bifidobacterium breve JCM 1192T cells on the rat cecal microbiota, in a preclinical synbiotic study groups of male WKAH/Hkm Slc rats were fed for 3 weeks with four different test diets: basal diet (group BD), basal diet supplemented with raffinose (group RAF), basal diet supplemented with encapsulated B. breve (group CB), and basal diet supplemented with both raffinose and encapsulated B. breve (group RCB). The bacterial populations in cecal samples were determined by fluorescence in situ hybridization (FISH) and terminal restriction fragment length polymorphism (T-RFLP). B. breve cells were detected only in the RCB group and accounted for about 6.3% of the total cells as determined by FISH analysis. B. breve was also detected only in the RCB group by T-RFLP analysis. This was in contrast to the CB group, in which no B. breve signals were detected by either FISH or T-RFLP. Increases in the sizes of the populations of Bifidobacterium animalis, a Bifidobacterium indigenous to the rat, were observed in the RAF and RCB groups. Principal-component analysis of T-RFLP results revealed significant alterations in the bacterial populations of rats in the RAF and RCB groups; the population in the CB group was similar to that in the control group (group BD). To the best of our knowledge, these results provide the first clear picture of the changes in the rat cecal microbiota in response to synbiotic administration.

Administration, Oral↗
PubMed2006

Alterations of cellular physiology in Escherichia coli in response to oxidative phosphorylation impaired by defective F1-ATPase.

The physiological changes in an F1-ATPase-defective mutant of Escherichia coli W1485 growing in a glucose-limited chemostat included a decreased growth yield (60%) and increased specific rates of both glucose consumption (168%) and respiration (171%). Flux analysis revealed that the mutant showed approximately twice as much flow in glycolysis but only an 18% increase in the tricarboxylic acid (TCA) cycle, owing to the excretion of acetate, where most of the increased glycolytic flux was directed. Genetic and biochemical analyses of the mutant revealed the downregulation of many TCA cycle enzymes, including citrate synthase, and the upregulation of the pyruvate dehydrogenase complex in both transcription and enzyme activities. These changes seemed to contribute to acetate excretion in the mutant. No transcriptional changes were observed in the glycolytic enzymes, despite the enhanced glycolysis. The most significant alterations were found in the respiratory-chain components. The total activity of NADH dehydrogenases (NDHs) and terminal oxidases increased about twofold in the mutant, which accounted for its higher respiration rate. These changes arose primarily from the increased (3.7-fold) enzyme activity of NDH-2 and an increased amount of cytochrome bd in the mutant. Transcriptional upregulation appeared to be involved in these phenomena. As NDH-2 cannot generate an electrochemical gradient of protons and as cytochrome bd is inferior to cytochrome bo3 in this ability, the mutant was able to recycle NADH at a higher rate than the parent and avoid generating an excess proton-motive force. We discuss the physiological benefits of the alterations in the mutant.

Acetic Acid↗
PubMed2006

Mechanism of growth inhibition by free bile acids in lactobacilli and bifidobacteria.

The effects of the free bile acids (FBAs) cholic acid (CA), deoxycholic acid (DCA), and chenodeoxycholic acid on the bioenergetics and growth of lactobacilli and bifidobacteria were investigated. It was found that these FBAs reduced the internal pH levels of these bacteria with rapid and stepwise kinetics and, at certain concentrations, dissipated DeltapH. The bile acid concentrations that dissipated DeltapH corresponded with the MICs for the selected bacteria. Unlike acetate, propionate, and butyrate, FBAs dissipated the transmembrane electrical potential (DeltaPsi). In Bifidobacterium breve JCM 1192, the synthetic proton conductor pentachlorophenol (PCP) dissipated DeltapH with a slow and continuous kinetics at a much lower concentration than FBAs did, suggesting the difference in mode of action between FBAs and true proton conductors. Membrane damage assessed by the fluorescence method and a viability decrease were also observed upon exposure to CA or DCA at the MIC but not to PCP or a short-chain fatty acid mixture. Loss of potassium ion was observed at CA concentrations more than 2 mM (0.4x MIC), while leakage of other cellular components increased at CA concentrations more than 4 mM (0.8 x MIC). Additionally, in experiments with membrane phospholipid vesicles extracted from Lactobacillus salivarius subsp. salicinius JCM 1044, CA and DCA at the MIC collapsed the DeltapH with concomitant leakage of intravesicular fluorescent pH probe, while they did not show proton conductance at a lower concentration range (e.g., 0.2x MIC). Taking these observations together, we conclude that FBAs at the MIC disturb membrane integrity and that this effect can lead to leakage of proton (membrane DeltapH and DeltaPsi dissipation), potassium ion, and other cellular components and eventually cell death.

Bifidobacterium↗
PubMed2005

Revision surgery for failed thermal capsulorrhaphy.

BACKGROUND: With the failure of thermal capsulorrhaphy for shoulder instability, there have been concerns with capsular thinning and capsular necrosis affecting revision surgery. PURPOSE: To report the findings at revision surgery for failed thermal capsulorrhaphy and to evaluate the technical effects on subsequent revision capsular plication. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Fourteen patients underwent arthroscopic evaluation and open reconstruction for a failed thermal capsulorrhaphy. The cause of the failure, the quality of the capsule, and the ability to suture the capsule were recorded. The patients were evaluated at follow-up for failure, which was defined as recurrent subluxations or dislocations. RESULTS: The origin of the instability was traumatic (n = 6) or atraumatic (n = 8). At revision surgery in the traumatic group, 4 patients sustained failure of the Bankart repair with capsular laxity, and the others experienced capsular laxity alone. In the atraumatic group, all patients experienced capsular laxity as the cause of failure. Of the 14 patients, the capsule quality was judged to be thin in 5 patients and ablated in 1 patient. A glenoid-based capsular shift could be accomplished in all 14 patients. At follow-up (mean, 35.4 months; range, 22 to 48 months), 1 patient underwent revision surgery and 1 patient had a subluxation, resulting in a failure rate of 14%. CONCLUSIONS: Recurrent capsular laxity after failed thermal capsular shrinkage is common and frequently associated with capsular thinning. In most instances, the capsule quality does not appear to technically affect the revision procedure.

Adolescent↗
PubMed2005

Development and assessment of a real-time pcr assay for rapid and sensitive detection of a novel thermotolerant bacterium, Lactobacillus thermotolerans, in chicken feces.

A new real-time PCR assay was successfully developed using a TaqMan fluorescence probe for specific detection and enumeration of a novel bacterium, Lactobacillus thermotolerans, in chicken feces. The specific primers and probe were designed based on the L. thermotolerans 16S rRNA gene sequences, and these sequences were compared to those of all available 16S rRNA genes in the GenBank database. The assay, targeting 16S rRNA gene, was evaluated using DNA from a pure culture of L. thermotolerans, DNA from the closely related bacteria Lactobacillus mucosae DSM 13345(T) and Lactobacillus fermentum JCM 1173(T), and DNA from other lactic acid bacteria in quantitative experiments. Serial dilutions of L. thermotolerans DNA were used as external standards for calibration. The minimum detection limit of this technique was 1.84 x 10(3) cells/ml of an L. thermotolerans pure culture. The assay was then applied to chicken feces in two different trials. In the first trial, the cell population was 10(4) cells/g feces on day 4 and 10(5) cells/g feces on days 11 to 18. However, cell populations of 10(6) to 10(7) cells/g feces were detected in the second trial. The total bacterial count, measured by 4',6-diamidino-2-phenylindole (DAPI) staining, was approximately 10(11) cells/g feces. These results suggest that in general, L. thermotolerans is a normal member of the chicken gut microbiota, although it is present at relatively low levels in the feces.

Animals↗
PubMed2005

Effects of difructose anhydride III (DFA III) administration on rat intestinal microbiota.

The effects of difructose anhydride III (di-D-fructofuranose-1,2':2,3'-dianhydride; DFA III) administration (3% DFA III for 4 weeks) on rat intestinal microbiota were examined using denaturing gradient gel electrophoresis (DGGE). According to DGGE profiles, the number of bacteria related to Bacteroides acidofaciens and uncultured bacteria within the Clostridium lituseburense group decreased, while that of bacteria related to Bacteroides vulgatus, Bacteroides uniformis and Ruminococcus productus increased in DFA III-fed rat cecum. In the cecal contents of DFA III-fed rats, a lowering of pH and an increase in short chain fatty acids (SCFAs), especially acetic acid, were observed. The DFA III-assimilating bacterium, Ruminococcus sp. M-1, was isolated from the cecal contents of DFA III-fed rats. The strain had 98% similarity with R. productus ATCC 27340T (L76595), and mainly produced acetic acid. These results confirmed that the bacteria harmful to host health were not increased by DFA III administration. Moreover, DFA III stimulated the growth of Ruminococcus sp. M-1 producing acetic acid, which may alter the intestinal microbiota towards a healthier composition. It is expected that DFA III would be a new candidate as a prebiotic.

Administration, Oral↗
PubMed2005

Effects of difructose anhydride III (DFA III) administration on bile acids and growth of DFA III-assimilating bacterium Ruminococcus productus on rat intestine.

The growth of DFA III-assimilating bacteria in the intestines of rats fed 3% DFA III for 2 weeks was examined. Sixty-four percent of the DFA III intake had been assimilated on day 3 of ingestion, and almost all of the DFA III was assimilated at the end of the experiment. The DFA III-assimilating bacterium, Ruminococcus productus, in DFA III-fed rats was in the stationary state of 10(8)-10(9) cells/g dry feces within a week from 10(6) cells/g dry feces on day 1 of DFA III ingestion. The number of R. productus cells was associated with the amount of DFA III excreted in the feces. The acetic acid produced from DFA III by R. productus lowered the cecal pH to 5.8. In control-fed rats and DFA III-fed rats, 94% of secondary bile acids and 94% of primary bile acids, respectively, were accounted for in the total bile acids analyzed. DFA III ingestion increased the ratio of primary bile acids and changed the composition of fecal bile acids. In conclusion, R. productus assimilated DFA III, produced short chain fatty acids, and the cecal pH was lowered. The acidification of rat intestine perhaps inhibited secondary bile acid formation and decreased the ratio of secondary bile acids. Therefore, it is expected that DFA III may prevent colorectal cancer and be a new prebiotic candidate.

Administration, Oral↗
PubMed2005

Enhanced glutamic acid production by a H+-ATPase-defective mutant of Corynebacterium glutamicum.

Previously we reported that a mutant of Corynebacterium glutamicum ATCC14067 with reduced H+-ATPase activity, F172-8, showed an approximately two times higher specific rate of glucose consumption than the parent, but no glutamic acid productivity under the standard biotin-limited culture conditions, where biotin concentration was set at 5.5 microg/l in the production medium (Sekine et al., Appl. Microbiol. Biotechnol., 57, 534-540 (2001)). In this study, various culture conditions were tested to check the glutamic acid productivity of strain F172-8. The mutant was found to produce glutamic acid under exhaustive biotin limitation, where the biotin concentration of the medium was set at 2.5 microg/l with much smaller inoculum size. When strain F172-8 was cultured under the same biotin-limited conditions using a jar fermentor, 53.7 g/l of glutamic acid was produced from 100 g/l glucose, while the parent produced 34.9 g/l of glutamic acid in a medium with 5.5 microg/l biotin. The glutamic acid yield of strain F172-8 also increased under Tween 40-triggered production conditions (1.2-fold higher than the parent strain). The amounts of biotin-binding enzymes were investigated by Western blot analysis. As compared to the parent, the amount of pyruvate carboxylase was lower in the mutant; however, the amount of acetyl-CoA carboxylase did not significantly change under the glutamic acid production conditions. To the best of our knowledge, this is the first report showing that the H+-ATPase-defective mutant of C. glutamicum is useful in glutamic acid production.

Biotin↗
PubMed2005

Diagnostic accuracy of clinical tests for the different degrees of subacromial impingement syndrome.

BACKGROUND: Several tests for making the diagnosis of rotator cuff disease have been described, but their utility for diagnosing bursitis alone, partial-thickness rotator cuff tears, and full-thickness rotator cuff tears has not been studied. The hypothesis of this study was that the degree of severity of rotator cuff disease affects the diagnostic values of the commonly used clinical tests. METHODS: Eight physical examination tests (the Neer impingement sign, Hawkins-Kennedy impingement sign, painful arc sign, supraspinatus muscle strength test, Speed test, cross-body adduction test, drop-arm sign, and infraspinatus muscle strength test) were evaluated to determine their diagnostic values, including likelihood ratios and post-test probabilities, for three degrees of severity in rotator cuff disease: bursitis, partial-thickness rotator cuff tears, and full-thickness rotator cuff tears. A forward stepwise logistic regression analysis was used to determine the best combination of clinical tests for predicting the various grades of impingement syndrome. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of the eight tests varied considerably. The combination of the Hawkins-Kennedy impingement sign, the painful arc sign, and the infraspinatus muscle test yielded the best post-test probability (95%) for any degree of impingement syndrome. The combination of the painful arc sign, drop-arm sign, and infraspinatus muscle test produced the best post-test probability (91%) for full-thickness rotator cuff tears. CONCLUSIONS: The severity of the impingement syndrome affects the diagnostic values of the commonly used clinical tests. The variable accuracy of these tests should be taken into consideration when evaluating patients with symptoms of rotator cuff disease.

Diagnostic Techniques and Procedures↗
PubMed2004

NMR characterization of three-disulfide variants of lysozyme, C64A/C80A, C76A/C94A, and C30A/C115A--a marginally stable state in folded proteins.

Our earlier NMR study showed that a two-disulfide variant of hen lysozyme containing intra-alpha-domain disulfide bridges, C6-C127 and C30-C115, is partially folded, with the alpha domain tightly folded to the nativelike conformation and the beta domain flexible or unfolded. With a view that the formation of a third disulfide bridge is a key for the accomplishment of the overall chain fold, three-dimensional structures of three-disulfide variants of hen lysozyme lacking one disulfide bridge (C64A/C80A, C76A/C94A, and C30A/C115A) were studied in detail using NMR spectroscopy. Amide hydrogen exchange rates were measured to estimate the degree of conformational fluctuation in a residue-specific manner. The structure of C76A/C94A was found to be quite similar to that of the wild type, except for the peptide segment of residues 74-78. The structure of C64A/C80A was considerably disordered in the entire region of the loop (residues 62-79). Further, it was found that a network of hydrogen bonds within the beta sheet and the 3(10) helix in the beta domain were disrupted and fluctuating. In C30A/C115A, the D helix was unstructured and the interface of the B helix with the D helix was significantly perturbed. However, the structural disorder generated in the hydrophobic core of the alpha domain was prevented by the C helix from propagating toward the beta domain. A marginally stable state in folded proteins is discussed based on the structures remaining in each three-disulfide variant.

Amides↗
PubMed2004

Return to play for rotator cuff injuries and superior labrum anterior posterior (SLAP) lesions.

The shoulder is a frequently injured joint in athletes, and the most common injuries in active patients include instability, rotator cuff injuries, and superior labrum lesions. These three types of injuries often involve different mechanisms of injury, variable methods of surgical repair, and different considerations in rehabilitation and return to play. This article focuses upon rotator cuff injuries and superior labrum lesions, treated nonoperatively and operatively. Return to play with these injuries depends upon many factors including upon the age of the patient, the severity of the pathology,the type of treatment rendered, and the expectations of the patient.

Athletic Injuries↗
PubMed2004

Shoulder arthroscopy: principles and practice.

Shoulder arthroscopy has an expanding role in the diagnostic and therapeutic management of shoulder disorders. This article describes the principles of shoulder arthroscopy, including basic technique,indications, and complications. The clinical applications to several shoulder pathologies, such as rotator cuff disorders, glenohumeral instability, and biceps anchor superior lesions, ar reviewed.

Acromioclavicular Joint↗
PubMed2004

The effects of di-D-fructofuranose-1,2':2,3'-dianhydride (DFA III) administration on human intestinal microbiota.

Di-D-fructofuranose-1,2':2,3'-dianhydride (DFA III) was shown to enhance Ca absorption in rat and human intestine. The effects of DFA III administration (9 g per day for 4 weeks that corresponded to 3-fold the optimal dosage of DFA III) on human intestinal microbiota were studied using denaturing gradient gel electrophoresis (DGGE). The major groups of human intestinal microbiota reported previously: the Bacteroides, the Clostridium coccoides group (Clostridium cluster XIVa), the Clostridium leptum group (Clostridium cluster IV), and the Bifidobacterium group were detected. The similarity of 30 DGGE profiles based on the V3 region (before and after administration to the 15 subjects) of the 16S rDNA were calculated using Pearson's correlation based on numbers, positions and intensity of bands, and then a dendrogram of DGGE profiles was constructed by the unweighted pair group method using arithmetic average (UPGMA) clustering method. By these analyses, no difference in DGGE profiles after DFA III administration was observed in healthy subjects, while two subjects with chronic constipation showed different profiles, namely on numbers, positions and the intensity of some bands. Their stools were softer and stool frequencies increased and they obtained relief from constipation.

Journal Article↗
PubMed2004

Effects of indigenous starter cultures on the microbial and physicochemical characteristics of Urutan, a Balinese fermented sausage.

Urutan is a Balinese traditional dry fermented sausage prepared from lean pork and various kinds of spice. Urutan is different from the European sausages, because it is fermented under warm condition with fluctuating temperatures of approximately 25 degrees C at night to 50 degrees C during sun drying. In this study, two of the 71 strains of lactic acid bacteria (LAB) isolated from natural urutan fermentation were used as starter cultures: Lactobacillus plantarum U201, the dominant LAB, and Pediococcus acidilactici U318, a bacteriocin producer. A soft urutan with yellowish brown color was produced using these strains as multiple starters. The starter cultures grew in characteristic succession which reconstructed the natural fermentation process. Lactobacilli were dominant until 48 h fermentation and pediococci dominated at the later stage of fermentation. Proliferation of starter cultures produced lactic acid which resulted in the decrease in pH and coagulation of soluble protein in urutan. Both strains could eliminate the Enterobacteriaceae in urutan after 24 h fermentation, and could suppress and eliminate the occurrence of micrococci at 120 h fermentation. By using a single starter culture, no succession was observed to occur in urutan and the time of elimination of Enterobacteriaceae was delayed. Thus, the strains of L. plantarum U201 and P. acidilactici U318 have great potential for use as multiple starter cultures in urutan fermentation.

Journal Article↗
PubMed2004

Isolation of a cadmium-releasing bacterium and characterization of its novel protease.

Microorganisms were screened for their ability to release cadmium from scallop hepatopancreas, which is the main residue after removing of the edible parts of scallop. The isolated strain, 23-0-11, identified as Arthrobacter nicotinovorans, secreted a protease which released cadmium from scallop hepatopancreas into the liquid medium. The molecular mass of the enzyme was estimated to be 27 kDa. The sequence of the 15 N-terminal amino acids of the protease showed no close similarity with any other protein. Compared with a commercial enzyme, the purified protease had greater ability to release cadmium. The enzyme activity was greatest at 50 degrees C and pH 7.0, and was enhanced in the presence of Ca(2+), Mg(2+) and Mn(2+), while being strongly inhibited by Co(2+). The inhibition profile by the serine protease inhibitor, phenylmethylsulphonyl fluoride (PMSF), confirmed that the protease belonged to the serine protease family.

Animals↗
PubMed2003

Molecular cloning of the gene for 2,6-beta-D-fructan 6-levanbiohydrolase from Streptomyces exfoliatus F3-2.

The gene encoding a 2,6-beta-D-fructan 6-levanbiohydrolase (LF2ase) (EC 3.2.1.64) that converts levan into levanbiose was cloned from the genomic DNA of Streptomyces exfoliatus F3-2. The gene encoded a signal peptide of 37 amino acids and a mature protein of 482 amino acids with a total length of 1560 bp and was successfully expressed in Escherichia coli. The similarities of primary structure were observed with levanases from Clostridium acetobutylicum, Bacillus subtilis, B. stearothermophilus (51.0-54.3%) and with LF2ase from Microbacterium levaniformans (53.9%). The enzyme from S. exfoliatus F3-2 shared the conserved six domains and the completely conserved five amino acid residues with family 32 glycosyl hydrolases, which include levanase, inulinase, and invertase. These observations led to the conclusion that the enzyme belongs to family 32 glycosyl hydrolases.

Amino Acid Sequence↗