Norikatsu Yuki

Yakult Central Institute for Microbiological Research, Musashino, Tōkyō, Japan

Are you Norikatsu Yuki?

Claim your profile

Publications (17)37.78 Total impact

  • [Show abstract] [Hide abstract] ABSTRACT: This study investigated the ability of the probiotic Bifidobacterium breve strain Yakult (BbY) to protect against infection, as well as the potentiation of BbY activity by the synbiotic combination of BbY and the prebiotic galactooligosaccharides (GOS). The study employed a mouse model of lethal intestinal multidrug-resistant Acinetobacter baumannii (MDRAb) infection. The endogenous intestinal microbiota was disrupted by the administration of multiple antibiotics, causing the loss of endogenous Bifidobacterium . Oral infection of these mice with MDRAb resulted in marked growth of this organism. Additional treatment of the infected mice with a sublethal dose of 5-fluorouracil (5-FU) induced systemic invasion by MDRAb and subsequent animal death. The continuous oral administration of BbY increased the survival rate and inhibited the intestinal growth and invasion by MDRAb in the infection model. Disruptions of the intestinal environment and barrier function in the infected mice were attenuated by BbY. Protection against the MDRAb infection was markedly potentiated by a synbiotic combination of BbY and GOS, although GOS by itself did not provide protection. Negative correlations were observed between intestinal MDRAb and BbY counts or acetic acid levels; positive correlations were observed between acetic acid levels and intestinal epithelium expression of tight-junction-related genes. These results demonstrated that pro/synbiotic markedly potentiated protection against fatal intestinal infection caused by a multidrug-resistant bacterium. Pro/synbiotic are presumed to provide protection by compensation for the disrupted indigenous populations, thereby maintaining the intestinal environments and barrier functions otherwise targeted during opportunistic infection by MDRAb.
    No preview · Article · Mar 2016 · Antimicrobial Agents and Chemotherapy
  • [Show abstract] [Hide abstract] ABSTRACT: Objectives: This study aims to establish the baseline profile of intestinal microbiota in pre-school and school-age Japanese children and to investigate the effects of a probiotic on the microbiota. Methods: We analyzed the intestinal microbiota and investigated the effects (before, during and after the ingestion period) on intestinal microbiota and the environment of 6 months of daily ingestion of a probiotic (Lactobacillus casei strain Shirota (LcS)-fermented milk). Results: We performed an open trial in 23 children (14 boys, 9 girls; age 7.7 ± 2.4 years (mean ± SD); BMI 19.6 ± 4.6). The composition of intestinal microbiota of healthy pre-school and school-age children resembled that of adults. During probiotic supplementation, the population levels of Bifidobacterium and total Lactobacillus increased significantly, while those of Enterobacteriaceae, Staphylococcus and Clostridium perfringens decreased significantly. A significant increase in fecal concentrations of organic acids and also a decrease in fecal pH were observed during the ingestion period. However, the patterns of fecal microbiota and intestinal environment were found to revert to the baseline levels (i.e. before ingestion) within 6 months following the cessation of probiotic intake. Conclusion: Regular intake of an LcS-containing probiotic product may modify the gut microbiota composition and intestinal environment in pre-school and school-age children while maintaining the homeostasis of the microbiota.
    No preview · Article · Oct 2015 · Annals of Nutrition and Metabolism
  • [Show abstract] [Hide abstract] ABSTRACT: We studied the effectiveness of the continuous intake of Lactobacillus casei strain Shirota (LcS)-fermented milk on inpatients living at facilities for the elderly (n=42, 82±10 years) in open trials that compared the pre- and post-intake. LcS-fermented milk was taken continuously for 6 months. Feces were sampled and analyses of fecal microflora, organic acid and pH measurement were performed. A reduction in the number of days that the inpatients had a fever, constipation and diarrhea was observed in the post-intake of the milk compared to the pre-intake. In the feces of the inpatients before the intake compared to those of staff (n=24, 40±12 years), Bifidobacterium decreased whereas Clostridium species increased However, Bifidobacterium proliferated without the detection of methicillin-resistant Staphylococcus in the samples after the intake. No bacteria causing nosocomial infections were detected among the staff. The acetic acid concentration increased and pH decreased in the feces of the inpatients after such intake. LcS-fermented milk is therefore considered to be useful for improving the clinical conditions, and the effects of the enteral microflora and environment in such inpatients. LcS-fermented milk may therefore have efficacy for reducing the risk of infection among elderly individuals residing at nursing homes.
    No preview · Article · Jan 2011 · International Journal of Probiotics and Prebiotics
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: The anti-infectious activity of lactobacilli against multi-drug resistant Salmonella enterica serovar Typhimurium DT104 (DT104) was examined in a murine model of an opportunistic antibiotic-induced infection. Explosive intestinal growth and subsequent lethal extra-intestinal translocation after oral infection with DT104 during fosfomycin (FOM) administration was significantly inhibited by continuous oral administration of Lactobacillus casei strain Shirota (LcS), which is naturally resistant to FOM, at a dose of 10(8) colony-forming units per mouse daily to mice. Comparison of the anti-Salmonella activity of several Lactobacillus type strains with natural resistance to FOM revealed that Lactobacillus brevis ATCC 14869(T) , Lactobacillus plantarum ATCC 14917(T) , Lactobacillus reuteri JCM 1112(T) , Lactobacillus rhamnosus ATCC 7469(T) and Lactobacillus salivarius ATCC 11741(T) conferred no activity even when they obtained the high population levels almost similar to those of the effective strains such as LcS, Lact. casei ATCC 334(T) and Lactobacillus zeae ATCC 15820(T) . The increase in concentration of organic acids and maintenance of the lower pH in the intestine because of Lactobacillus colonization were correlated with the anti-infectious activity. Moreover, heat-killed LcS was not protective against the infection, suggesting that the metabolic activity of lactobacilli is important for the anti-infectious activity. These results suggest that certain lactobacilli in combination with antibiotics may be useful for prophylaxis against opportunistic intestinal infections by multi-drug resistant pathogens, such as DT104. Antibiotics such as FOM disrupt the metabolic activity of the intestinal microbiota that produce organic acids, and that only probiotic strains that are metabolically active in vivo should be selected to prevent intestinal infection when used clinically in combination with certain antibiotics.
    Full-text · Article · Oct 2010 · Journal of Applied Microbiology
  • [Show abstract] [Hide abstract] ABSTRACT: We developed a novel selective medium, modified-rhamnose-2,3,5-triphenyltetrazolium chloride-LBS-vancomycin agar (M-RTLV agar), that utilizes the fermentability of L-rhamnose to distinguish Lactobacillus casei and Lactobacillus paracasei from Lactobacillus rhamnosus. Whereas L. casei and L. paracasei formed red colonies on the M-RTLV agar, L. rhamnosus formed either pink-toned colonies or white colonies with a red spot. An intervention study was conducted to confirm the capability of M-RTLV agar to detect ingested L. casei when recovered from human feces. Subjects consumed one bottle daily of a fermented milk product (Yakult or Yakult Light, which contains L. casei strain Shirota; LcS) for 7 days. Diluents of the fecal samples were cultivated on M-RTLV agar. We were able to enumerate circular medium-sized red colonies, which were morphologically similar to L. casei/L. paracasei but clearly distinguishable from the remaining colonies owing to the color difference. These colonies were then subjected to enzyme-linked immunosorbent assay in order to identify the LcS. The viable counts of LcS were 6.6+/-0.7 log(10) CFU/g feces after intake of Yakult and 6.5+/-0.6 log(10) CFU/g feces after intake of Yakult Light (mean+/-SD).
    No preview · Article · Mar 2010 · International journal of food microbiology
  • [Show abstract] [Hide abstract] ABSTRACT: Infants with severe congenital anomaly often need to undergo operation followed by antibiotic therapy. As a result they inevitably acquire abnormal intestinal microbiota, which cause severe infections such as necrotizing enterocolitis. Also, intestinal function deteriorates and their nutritional state is very poor. In order to prevent these situations probiotic therapy is proposed as an effective supporting treatment. Probiotic therapy were therefore applied to infants with severe congenital anomaly as early as possible to ascertain its efficacy. As probiotics, two bacteria were used: Bifidobacterium breve Yakult and Lactobacillus casei Shirota. Probiotic therapy was used in four infants with severe congenital anomaly as early as possible after surgery. Their intestinal microbiota and physical growth were followed through the treatment course. Two patients suffered from meconium peritonitis with ileal atresia. One patient was born with complex anomalies (omphalocele, bladder exstrophy, myelomeningocele). The fourth patient suffered from complete urorectal septum malformation. The intestinal microbiota of these four patients was first induced to be probiotic dominant and finally changed to commensal anaerobe dominant that was similar to normal intestinal microbiota. Pathogenic bacteria were seldom detected. The patients' physical growth was excellent despite short bowel and pulmonary hypoplasia. Probiotic therapy was effective in inducing probiotic dominant intestinal microbiota and normal intestinal microbiota in infants with severe congenital anomalies. As a result their intestinal absorptive functions were activated and severe infections were completely prevented. All of the infants grew well despite their physical disadvantages.
    No preview · Article · Sep 2009 · Pediatrics International
  • [Show abstract] [Hide abstract] ABSTRACT: We evaluated the effects of ingestion of a synbiotic fermented milk beverage containing Lactobacillus casei strain Shirota (LcS) at 3 × 1010 and transgalactosylated oligosaccharides (GOS) at 2.5 g per 80 ml (once a day, 2 weeks) on the defecation frequency in 35 female university students with constipation as well as the defecation frequency, intestinal microflora, and intestinal environment in elderly persons in whom the intestinal microflora and the levels of putrefactive metabolites were abnormal in a placebo-controlled double-blind study. In the female students, the defecation frequency after 1 week of synbiotic fermented milk beverage ingestion was significantly higher than that after 1 week of placebo ingestion or before ingestion. In the elderly persons, the fecal Bifidobacterium and Lactobacillus bacterial counts after 1 and 2 weeks of synbiotic fermented milk beverage ingestion were significantly higher than those after placebo ingestion or before ingestion (p<0.05 and p<0.01, respectively). The fecal lecithinase-positive Clostridium bacterial count after 1 week of synbiotic fermented milk beverage ingestion and the fecal Enterobacteriaceae bacterial counts after 1 and 2 weeks of synbiotic fermented milk beverage ingestion were significantly lower than those after placebo ingestion (p<0.05). LcS at 107 CFU per gram of stool was collected during the ingestion period. The acetic acid levels after 1 and 2 weeks of synbiotic fermented milk beverage ingestion were significantly higher than those after placebo ingestion (p<0.01). The stool pH values after 1 and 2 weeks of synbiotic fermented milk beverage ingestion and the ammonia and phenol levels after 2 weeks of synbiotic fermented milk beverage ingestion were significantly lower than those after placebo ingestion (p<0.05). These results suggest that ingestion of the synbiotic fermented milk beverage containing LcS and GOS improves the stool quality, intestinal microflora, and intestinal environment.
    No preview · Article · Jan 2006
  • [Show abstract] [Hide abstract] ABSTRACT: Probiotic and prebiotic therapies are potent new strategies to treat various intestinal diseases, including inflammatory bowel disease and viral and bacterial infections. Synbiotics is defined as the combined use of probiotics and prebiotics and is expected to have a stronger effect on intestinal diseases than probiotics or prebiotics alone, but there has been no report of its clinical application. The authors designed a protocol for synbiotic therapy composed of Bifidobacterium breve, Lactobacillus casei, and galactooligosaccharides and preliminarily ascertained its clinical effects in humans. This protocol of synbiotic therapy was applied for more than 1 year to 7 malnourished patients with short bowels who suffered from refractory enterocolitis. The therapeutic protocol improved the intestinal bacterial flora (inducing the domination by anaerobic bacteria and suppressing the residence of pathogenic bacteria) and increased short chain fatty acids in the feces (from 27.8 to 65.09 micromol/g wet feces). All patients but 1 accelerated their body weight gain, and 5 patients showed increased serum rapid turnover proteins. This protocol for synbiotic therapy might be a potent modulator of intestinal flora and a promising strategy to treat short bowel patients with refractory enterocolitis.
    No preview · Article · Dec 2004 · Journal of Pediatric Surgery
  • No preview · Article · Jul 2003 · Pediatrics International
  • [Show abstract] [Hide abstract] ABSTRACT: To demonstrate the beneficial effects of synbiotic therapy (combined use of probiotics and prebiotics) in critically ill patients, we designed a new protocol for such therapy. Three agents were used as synbiotics: Bifidobacterium breve, Lactobacillus casei, and galactooligosaccharides. More than 1 x 10(9) of probiotic bacteria were contained in each 1.0 g pack. We administered 3.0 g per day of each agent to the patient.A critically ill 9-month-old girl with laryngotracho-esophageal cleft (type IV) was treated by our new synbiotic therapy. Abundant amounts of synbiotic bacteria were detected in the feces which suggests that these administered bacteria affected intestinal function in situ. Bowel movements resumed soon after the commencement of synbiotic therapy and considerable amounts of short chain fatty acids were detected in the feces. Growth of the patient was satisfactory under this treatment. Our new synbiotic therapy had a beneficial effect to improve intestinal function. We recommend synbiotic therapy for critically ill patients in intensive care units as an important immunonutritional therapy.
    No preview · Article · Jan 2003 · Clinical Nutrition
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: Lactobacillus equi sp. nov. is described on the basis of 18 strains isolated as one of the predominant intestinal lactobacilli from horse faecal specimens. These 18 strains were isolated from 10 horses of 6 different farms out of 20 horses of 10 farms examined. They were gram-positive, facultatively anaerobic, catalase-negative, non-spore-forming, non-motile, lactic-acid-homofermentative rods. The DNA G+C content was 38.9+/-0.8 mol %. DNA-DNA hybridization failed to associate these strains closely with any of the validly described type strains used. Analysis of the 16S rRNA gene sequence of representative strain YIT 0455T revealed that the new isolates represent a new Lactobacillus species, for which the name Lactobacillus equi is proposed. The type strain is YIT 0455T (= ATCC BAA-261T = JCM 10991T).
    Full-text · Article · Feb 2002 · International Journal of Systematic and Evolutionary Microbiology
  • Source
    Full-text · Article · Oct 2001 · Digestive Diseases and Sciences
  • No preview · Article · Aug 2001 · Digestive Diseases and Sciences
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: Selective adhesion to only certain epithelia is particularly common among the bacterial members of the indigenous microflora of mammals. We have found that the stratified squamous epithelium of the nonsecreting area of horse stomach is colonized by gram-positive rods. The microscopic features of a dense layer of these bacteria on the epithelium were found to be similar to those reported in mice, rats, and swine. Adhering microorganisms were isolated and identified asLactobacillus salivarius, L. crispatus,L. reuteri, and L. agilis by DNA-DNA hybridization and 16S rRNA gene sequencing techniques. These lactobacilli associated with the horse, except for L. reuteri, were found to adhere to horse epithelial cells in vitro but not to those of rats. A symbiotic relationship of these lactobacilli with the horse is suggested.
    Full-text · Article · Dec 2000 · Applied and Environmental Microbiology
  • No preview · Article · Jun 1999 · Composite Structures
  • Yukiko SAKAITANI · Norikatsu YUKI · Yoko TAGAMI · Masami MOROTOMI
    No preview · Article · May 1999 · Nippon Saikingaku Zasshi
  • [Show abstract] [Hide abstract] ABSTRACT: Lactobacillus casei strain Shirota (LCS) is a probiotic bacterium used in the production of fermented milk products and lactic acid bacteria preparations. To investigate the survival of LCS in the gastrointestinal tract, we have developed a selective medium and specific monoclonal antibodies to isolate and identify this strain. Selective LLV agar medium was prepared by modifying LBS medium, a selective medium for lactobacilli, through the replacement of glucose with lactitol as a carbon source and vancomycin as a selective antibiotic. Culture in LLV agar medium followed by ELISA using monoclonal antibodies specific for LCS was able to detect the organism in faeces. Using this method, we studied the faecal recovery of LCS in individuals who drank 125 ml of fermented milk which contained 10(10) live LCS for 3 days. The mean recovery was about 10(7) live bacteria per gram of faeces, indicating that LCS survived transit through the gastrointestinal tract after ingestion of the fermented milk.
    No preview · Article · May 1999 · International Journal of Food Microbiology