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biBackground:/i/bRats are a major carrier of several pathogens, including zoonotic pathogens that can cause fatal diseases in humans. Indonesia has one of the fastest growing populations, with high infestation of rats in urban areas. Therefore, this study aims to assess the seropositivity of zoonotic pathogens in rats from four markets in Bogor, Indonesia.biMaterials and Methods:/i/bA total of 80 brown rats (iRattus norvegicus/i) were captured from the markets and screened for the presence of some zoonotic pathogens, specifically hantavirus,iLeptospira/ispp.,iOrientia tsutsugamushi/i, tick-borne encephalitis virus (TBEV), and lymphocytic choriomeningitis virus (LCMV) antibodies, using indirect fluorescence assay or enzyme-linked immunosorbent assay.biResults:/i/bAmong the 80 rats, 40% were seropositive for hantavirus, 36.3% foriLeptospira/ispp., 11.3% foriO. tsutsugamushi/i, 6.3% for TBEV, and 0% for LCMV.biConclusion:/i/bOverall, these results indicate that rats in Bogor pose a potential zoonotic risk to humans.

The microbiome is believed to be established during the birthing process through exposure to the maternal microbiome and immediate external environment. The absence of a microbiome prior to birth is based on the sterile womb hypothesis, which was formulated at the beginning of the 20th century and is supported primarily by the culture-based approach in microbiological studies.Findings of bacterial presence in products of fertilization such as the placenta, amniotic fluid, foetal membranes, and umbilical cord blood in studies using next-generation DNA sequencing technologies began to challenge the sterile nature of the intrauterine environment during gestation. These studies have been mainly criticized by their approach to contamination and inconclusive evidence of viability. The implications of bacterial presence in utero are far reaching in medicine and basic sciences. If commensal bacteria exist in the foetus, antibiotic therapies in pregnancy particularly for asymptomatic cases will need to be re-evaluated. Experimental studies utilizing gnotobiology may also be impacted by a realignment of theory.This review of existing literature aims to provide insight into the existence of bacteria in utero, specifically the foetal microbiome through analysis of experimental evidence and theoretical concepts, and to suggest approaches that may further provide clarity into this inquiry.

Rats are an important maintenance host of Leptospira spp., the causative agents of leptospirosis, a zoonotic disease with worldwide distribution. Rats are traded as food in the Mekong Delta, where Cambodia exports tons of rats to Vietnam. Handling wild rats is a potential health risk, but the information on Leptospira spp. carried by rats traded in the region remains limited. In this study, we investigated the carriage of Leptospira spp. in rats exported from Cambodia to Vietnam using bacterial culture, nested PCR and DNA sequencing. Isolates were then assessed using serological analysis and whole-genome sequencing (WGS), and Leptospira DNA detected in rat kidney tissues was also analysed by multilocus sequence typing (MLST). Seventy-two rats (2 Bandicota indica, 57 Rattus argentiventer, 11 R. losea, 1 R. norvegicus and 1 R. rattus) were subjected to bacterial culture, and three L. borgpetersenii serogroup Javanica isolates were obtained from R. argentiventer (5.3%). WGS revealed that although Cambodian isolates were genetically related to L. borgpetersenii serogroup Javanica strains widely distributed in East and South-East Asian countries, they formed a different cluster from other strains. In addition to the three L. borgpetersenii sequences, the flaB sequence of L. interrogans was detected in 18 R. argentiventer and 7 R. losea kidney tissue samples (38.9%) using nested PCR followed by DNA sequencing. The L. interrogans flaB-positive samples were further analysed by MLST, revealing that seven housekeeping genes (glmU, pntA, sucA, tpiA, pfkB, mreA and caiB) contained novel sequences with distinct lineages from other sequence types. This study revealed a high prevalence of Leptospira spp. among rats exported from Cambodia to Vietnam, indicating a potential risk to people engaging in rat trade and demonstrating that a fastidious L. interrogans strain circulates among Cambodian rats.

The prevalence of antimicrobial resistance (AMR) in small mammals dwelling in the city was used as an indicator of AMR bacteria in the environment. We captured 87 small mammals (79 brown rats and 8 house shrews) in four markets, Bogor, Indonesia in October 2019, and we obtained 20 AMR Escherichia coli (E. coil) from 18 brown rats and two house shrews. Of these, eight isolates were determined to be multi-drug resistant (MDR) E. coli, suggesting the potential contamination of AMR E. coli in the markets in Bogor, Indonesia, and that mammals, including humans, are at risk of infection with AMR E. coli from environment.

Antimicrobial resistance (AMR) is a global public health concern for both clinical and veterinary medicine. Rodent feces are one of the major infectious sources of zoonotic pathogens including AMR bacteria. So far, there are limited studies reported focused on Escherichia coli isolated in rodent feces from rural and suburban areas in Vietnam. In this study, we investigated the prevalence of antimicrobial resistance in E. coli isolated from feces samples of 144 urban rodents caught in Hanoi, Vietnam. A total of 59 AMR E. coli was isolated from urban rodents of which 42 were multidrug-resistant (MDR) isolates (resistance to at least three classes of antimicrobial agents), four were extended-spectrum β-lactamase (ESBL) producing isolates and five were colistin-resistant isolates. The highest prevalence of the resistance was against ampicillin (79.7%: 47/59), followed by tetracycline (78.0%: 46/59), nalidixic acid (67.8%: 40/59), sulfamethoxazole-trimethoprim (59.3%: 35/59), chloramphenicol (45.8%: 27/59), ciprofloxacin (44.1%: 26/59), cefotaxime (30.5%: 18/59), cefodizime (23.7%: 14/59), amoxicillin-clavulanate (22.0%: 13/59), and gentamicin (22.0%: 13/59). With regard to the virulence genes associated with diarrheagenic E. coli (DEC), only aaiC gene found in one AMR isolate. In general, the use of antimicrobials does not aim to treat rodents except for companion animals. However, our findings show the carriage of AMR and MDR E. coli in urban rodents and highlight the potential risk of rodents in Hanoi acting as a reservoir of transferable MDR E. coli, including ESBL-producing, colistin-resistant E. coli, and virulence-associated with DEC.

Leptospirosis is a zoonotic disease that is caused by pathogenic spirochaetes of Leptospira spp. and it has become a public health concern in urban localities in the tropics. Rats are important reservoir animals for the transmission of leptospirosis in urban areas. Leptospirosis is considered endemic in Vietnam. However, information on the causative Leptospira genotypes and serotypes in the country is limited. We investigated the carrier status of Leptospira spp. in rats captured in Hanoi by culturing and DNA detection. Isolates were characterized using a serological method and multiple-locus variable-number tandem repeat analysis (MLVA). We captured 144 rats (1 Rattus argentiventer, 135 R. norvegicus, and 8 R. rattus) and obtained 17 L. interrogans, determined by rrs sequencing, from R. norvegicus (12.6%). Sixteen of the isolates were serogroup Bataviae. Five of the 16 isolates exhibited an MLVA type identical to that of the serovar Bataviae reference strain Van Tienen, while there were nine repeats for the other 11 isolates at VNTR31 compared with the reference strain. The remaining isolate grew poorly, and we were unable to determine its serogroup. However, it had an MLVA type matching those of serogroup Pomona strains isolated from R. norvegicus in Japan. Three different flaB sequences were detected in 23 out of 81 R. norvegicus kidney tissue samples (28.4%) using nested PCR followed by DNA sequencing. Two of the sequences were identical with those of serogroups Bataviae and Pomona, and no strain with another sequence was detected in the present study. The present study reveals a high prevalence rate of L. interrogans among R. norvegicus in Hanoi, Vietnam, indicating a potential risk of rat-borne leptospirosis in the area. The present study also demonstrates that a fastidious L. interrogans strain circulates among rats and that molecular detection is crucial in facilitating the accurate determination of reservoir animals.

Objectives The impacts of modernization on toxic heavy metal exposure and essential trace element intake in indigenous populations of subsistence societies are unknown. We assessed urinary trace element concentrations in rural residents of Northern Laos and examined associations with levels of modernization. Methods A cross-sectional study was conducted comprising 380 residents of three villages in Northern Laos with different levels of modernization. We surveyed general characteristics and measured the weight and height of 341 participants. Arsenic, cadmium, lead, and selenium concentrations were measured in spot urine samples by inductively coupled plasma mass spectrometry. We examined associations between urinary trace element concentrations and variables related to modernization (village, roofing material, possessions index [total number of possessions], and body mass index [BMI]) using multilevel analyses with household as a random effect, after adjusting for sex, age, and smoking status. Results Urinary concentrations of arsenic and cadmium were high, while those of lead and selenium were low in comparison to previous reports of populations in non-contaminated regions or without excess/deficiency. We observed associations between urinary trace element concentrations and village-level modernization: lead and selenium concentrations were higher in more modernized villages and cadmium concentration was highest in the least modernized village. Urinary arsenic concentration was not predicted by the modernization level of a village, although we observed significant differences among villages. In addition, urinary selenium concentration was higher in participants inhabiting more modernized houses. Conclusion Modernization of villages may impact toxic heavy metal exposure and selenium intake in rural residents of Northern Laos.

Japanese encephalitis virus (JEV) is transmitted between swine, migratory birds, and Culex mosquitoes, and has circulated indigenously in Asia for almost a century. Despite being the country with the highest JEV diversity, surveillance targeting of Indonesia’s vectors is scarce. This study collected mosquitoes from several locations in Tabanan Regency, Bali Island, Indonesia. We captured and classified 3,032 adult Culex mosquitoes into seven species, with Culex vishnui subgroup mosquitoes making up approximately 90% of the total. Japanese encephalitis virus was identified by next-generation sequencing (NGS) analysis of a Cx. vishnui mosquito pool. Genetic and phylogenetic analysis revealed the JEV as genotype (G) IV. The nucleotide identity was 99% with other JEV GIV isolates obtained from swine sera in 2017 on Bali Island and from a human patient in Australia with a travel history to Bali in 2019. This finding indicated that JEV GIV persists in restricted areas and is circulating between swine-mosquito vectors.

The prevalence of antimicrobial resistance (AMR) in small mammals dwelling in the city was used as an indicator of AMR bacteria in the environment. We captured 87 small mammals (79 brown rats and 8 house shrews) in four markets, Bogor, Indonesia in October 2019, and we obtained 20 AMR Escherichia coli (E. coil) from 18 brown rats and two house shrews. Of these, eight isolates were determined to be multi-drug resistant (MDR) E. coli, suggesting the potential contamination of AMR E. coli in the markets in Bogor, Indonesia, and that mammals, including humans, are at risk of infection with AMR E. coli from environment.

Recent research suggests that protein deficiency symptoms are influenced by the intestinal microbiota. We investigated the influence of low protein diet on composition of the intestinal microbiota through animal experiments. Specific pathogen-free (SPF) mice were fed one of four diets (3, 6, 9, or 12% protein) for 4 weeks (n = 5 per diet). Mice fed the 3% protein diet showed protein deficiency symptoms such as weight loss and low level of blood urea nitrogen concentration in their serum. The intestinal microbiota of mice in the 3% and 12% protein diet groups at day 0, 7, 14, 21 and 28 were investigated by 16S rRNA gene sequencing, which revealed differences in the microbiota. In the 3% protein diet group, a greater abundance of urease producing bacterial species was detected across the duration of the study. In the 12% diet protein group, increases of abundance of Streptococcaceae and Clostridiales families was detected. These results suggest that protein deficiency may be associated with shifts in intestinal microbiota.

ObjectiveAlthough immunoglobulin A (IgA) is abundantly expressed in the gut and known to be an important component of mucosal barriers against luminal pathogens, its precise function remains unclear. Therefore, we tried to elucidate the effect of IgA on gut homeostasis maintenance and its mechanism.DesignWe generated various IgA mutant mouse lines using the CRISPR/Cas9 genome editing system. Then, we evaluated the effect on the small intestinal homeostasis, pathology, intestinal microbiota, cytokine production, and immune cell activation using intravital imaging.ResultsWe obtained two lines, with one that contained a tm/tm) and the other that lacked the most constant region of the IgH α chain, which resulted in the deficiency of IgA production (IgA−/−). IgA−/− exhibited spontaneous inflammation in the ileum but not the other parts of the gastrointestinal tract. Associated with this, there were significantly increased lamina propria CD4+ T cells, elevated productions of IFN-γ and IL-17, increased ileal segmented filamentous bacteria and skewed intestinal microflora composition. Intravital imaging using Ca2+ biosensor showed that IgA−/− had elevated Ca2+ signalling in Peyer’s patch B cells. On the other hand, IgAtm/tm seemed to be normal, suggesting that the IgA cytoplasmic tail is dispensable for the prevention of the intestinal disorder.ConclusionIgA plays an important role in the mucosal homeostasis associated with the regulation of intestinal microbiota and protection against mucosal inflammation especially in the ileum.

Protective effect of quercetin on high-fat diet-induced non-alcoholic fatty liver disease in mice has been reported. Recent research has revealed that several intestinal bacteria metabolize quercetin. We hypothesize that the difference in composition of intestinal microbiota affects quercetin absorption from the intestine. Germ-free BALB/cA female mice (18 weeks old) were randomly divided into four groups and orally administered with fecal suspension from four human individuals (HF1, HF2, HF3, HF4) to produce the human microbiota-associated mice. All mice were fed the 0.05% quercetin-containing pelleted diet for four weeks. Significant differences were observed in plasma total cholesterol and cecal microbiota among the four groups. Plasma quercetin concentration was significantly higher in the HF3 group than in the HF1 group. The plasma isorhamnetin/quercetin ratio showed significant negative correlation with visceral fat levels (r = −0.544, p = 0.013). Positive correlation was observed between the Log10 Enterobacteriaceae count and the plasma quercetin metabolites. Principal component analysis showed that all groups were distributed in different regions by using the correlation diagram with the second and third principal component. This study indicates that intestinal microbiota of human microbiota-associated mice inoculated with different fecal suspensions react to dietary quercetin in different ways.

OBJECTIVE To elucidate the pathogenesis of postpancreatectomy diabetes mellitus (PPDM). RESEARCH DESIGN AND METHODS Forty-eight patients without diabetes undergoing either pancreatoduodenectomy (PD) (n = 20) or distal pancreatectomy (DP) (n = 28) were included. A 75-g oral glucose tolerance test was performed every 6 months. Microbiome composition and short-chain fatty acids (SCFAs) in feces were examined before and 6 months after surgery. The association of histological characteristics of the resected pancreas with PPDM was examined. RESULTS During follow-up (median 3.19 years), 2 of 20 PD patients and 16 of 28 DP patients developed PPDM. Proteobacteria relative abundance, plasma glucagon-like peptide 1 (GLP-1), and fecal butyrate levels increased only after PD. Postsurgical butyrate levels were correlated with postsurgical GLP-1 levels. With no significant difference in the volume of the resected pancreas between the surgical procedures, both β-cell and α-cell areas in the resected pancreas were significantly higher in DP patients than in PD patients. In DP patients, the progressors to diabetes showed preexisting insulin resistance compared with nonprogressors, and both increased α- and β-cell areas were predictors of PPDM. Furthermore, in DP patients, α-cell and β-cell areas were associated with ALDH1A3 expression in islets. CONCLUSIONS We postulate that a greater removal of β-cells contributes to the development of PPDM after DP. Islet expansion along with preexisting insulin resistance is associated with high cellular plasticity, which may predict the development of PPDM after DP. In contrast, PD is associated with alterations of gut microbiome and increases in SCFA production and GLP-1 secretion, possibly protecting against PPDM development.

Francisella tularensis, which causes tularemia, is an intracellular gram-negative bacterium. F. tularensis has received significant attention in recent decades because of its history as a biological weapon. Thus, development of novel vaccines against tularemia has been an important goal. The attenuated F. tularensis strain ΔpdpC, in which the pathogenicity determinant protein C gene (pdpC) has been disrupted by TargeTron mutagenesis, was investigated as a potential vaccine candidate for tularemia in the present study. C57BL/6J mice immunized s.c. with 1 × 106 CFUs of ΔpdpC were challenged intranasally with 100× the median lethal dose (LD50 ) of a virulent SCHU P9 strain 21 days post immunization. Protection against this challenge was achieved in 38% of immunized C57BL/6J mice administered 100 LD50 of this strain. Conversely, all unimmunized mice succumbed to death 6 days post challenge. Survival rates were significantly higher in vaccinated than in unimmunized mice. In addition, ΔpdpC was passaged serially in mice to confirm its stable attenuation. Low bacterial loads persisted in mouse spleens during the first to tenth passages. No statistically significant changes in the number of CFUs were observed during in vivo passage of ΔpdpC. The inserted intron sequences for disrupting pdpC were completely maintained even after the tenth passage in mice. Considering the stable attenuation and intron sequences, it is suggested that ΔpdpC is a promising tularemia vaccine candidate.

Tularemia is a severe infectious zoonotic disease caused by Francisella tularensis. Although F. tularensis is considered to be a potential biological weapon due to its high infectivity and mortality rate, no vaccine has been currently licensed. Recently, we reported that F. tularensis SCHU P9 derived ΔpdpC strain lacking the pathogenicity determinant protein C gene conferred stable and good protection in a mouse lethal model. In this study, the protective effect of ΔpdpC was evaluated using a monkey lethal model. Two cynomolgus macaques (Macaca fascicularis) intratracheally challenged with the virulent strain SCHU P9 were euthanized on 7 and 11 days post-challenge after the development of severe clinical signs. The bacterial replication in alveolar macrophages and type II epithelial cells in the lungs would cause severe pneumonia accompanied by necrosis. Conversely, two animals subcutaneously immunized with ΔpdpC survived 3 weeks after SCHU P9 challenge. Though one of the two animals developed mild symptoms of tularemia, bacterial replication was limited in the respiratory organs, which may be due to a high level of humoral and cellular immune responses against F. tularensis. These results suggest that the ΔpdpC mutant would be a safe and promising candidate as a live attenuated tularemia vaccine.

Severe fever with thrombocytopenia syndrome (SFTS) was detected for the first time in China in 2011. Since then, human cases have been reported in endemic regions, including Japan. To investigate the presence of tick-borne pathogens in Tokyo, 551 ticks (266 samples) were collected from October 2015 to October 2016. Although the SFTS virus was not detected by RT-PCR, a novel phlebovirus was detected in one sample. In a phylogenetic analysis based on the partial nucleotide sequences of the L and S segments of the virus, the virus clustered with Lesvos virus (Greece), Yongjia tick virus, and Dabieshan tick virus (China). Further studies involving virus isolation are required to characterize this novel phlebovirus and to expand the epidemiological knowledge of related pathogens.

Non-primate hepacivirus (NPHV) is recently identified as a closely related homologue of hepatitis C virus. The previous studies showed a high prevalence of NPHV infection among Japanese domestic horses originated from abroad. The historical distribution of NPHV among horses in Japan, therefore, is still unknown. In this study, seroepidemiological study of NPHV was conducted using 335 sera from five breeds of Japanese native horses. These horses are maintained as the pedigree and are reared apart from other horse breeds. The detection of antibodies against NPHV were conducted by western blot analysis using the recombinant protein of the NPHV core protein. The antibodies against NPHV were detected in all five breeds, 83 out of 335 (23.4%) horses. These results suggested that NPHV was circulating among Japanese native horses.

Francisella tularensis, which causes tularemia, is an intracellular gram-negative bacterium. F. tularensis has received significant attention in recent decades because of its history as a biological weapon. Thus, development of novel vaccines against tularemia has been an important goal. The attenuated F. tularensis strain ΔpdpC, in which the pathogenicity determinant protein C gene (pdpC) has been disrupted by TargeTron mutagenesis, was investigated as a potential vaccine candidate for tularemia in the present study. C57BL/6J mice immunized s.c. with 1 × 10

It has been demonstrated that intestinal commensal bacteria induce immunoglobulin (Ig) A production by promoting the development of gut-associated lymphoid tissues in the small intestine. However, the precise mechanism whereby these bacteria modulate IgA production in the large intestine, which harbors the majority of intestinal commensals, is poorly understood. In addition, it is not known which commensal bacteria induce IgA production in the small intestine and which induce production in the large intestine. To address these issues, we generated gnotobiotic mice mono-associated with different murine commensal bacteria by inoculating germ-free (GF) mice with Lactobacillus johnsonii or Bacteroides acidifaciens. In GF mice, IgA production was barely detectable in the small intestine and was not detected in the large intestine. Interestingly, total IgA secretion in the large intestinal mucosa of B. acidifaciens mono-associated (BA) mice was significantly greater than that of GF and L. johnsonii mono-associated (LJ) mice. However, there was no difference in total IgA production in the small intestine of GF, LJ and BA mice. In addition, in the large intestine of BA mice, the expression of IgA(+) cells and germinal center formation were more remarkable than in GF and LJ mice. Furthermore, B. acidifaciens-specific IgA was detected in the large intestine of BA mice. These results suggest that the production of IgA in the large intestine may be modulated by a different mechanism than that in the small intestine, and that B. acidifaciens is one of the predominant bacteria responsible for promoting IgA production in the large intestine.

The transition of intestinal microbiota with age has been well described in humans. However, the age-related changes in intestinal microbiota of cats have not been well studied. In the present study, we investigated the composition of intestinal microbiota of cats in 5 different age groups (pre-weanling, weanling, young, aged, senile) with a culture-based method. For lactobacilli and bifidobacteria, we also quantified with molecular-based method, real-time PCR. The results suggested that the composition of the feline intestinal microbiota changes with age, while the changes were different from those of humans and dogs. Bifidobacteria which are predominant in human intestine or lactobacilli which are predominant in dog intestine, did not appear to be important in cat intestines. Enterococci, instead, seem to be major lactic acid producing bacteria in cats. We also identified lactobacilli and bifidobacteria at the species level based on 16S rRNA gene sequences and found that the species composition of Lactobacillus also changed with age.

Probiotics, such as lactic acid bacteria (LAB) and Bacillus subtilis var. natto, have been shown to modulate immune responses. It is important to understand how probiotic bacteria impact intestinal epithelial cells (IECs), because IECs are the first line of defense at the mucosal surface barrier and their activities substantially affect the gut microenvironment and immunity. However, to date, their precise mechanism remains unknown due to a lack of analytical systems available for live animal models. Recently, we generated a conditional Ca2+ biosensor Yellow Cameleon (YC3.60) transgenic mouse line and established 5D (x, y, z, time, and Ca2+) intravital imaging systems of lymphoid tissues including those in Peyer’s patches and bone marrow. In the present study, we further advance our intravital imaging system for intestinal tracts to visualize IEC responses against orally administrated food compounds in real time. Using this system, heat-killed Bacillus subtilis natto, a probiotic TTCC012 strain, is shown to directly induce Ca2+ signaling in IECs in mice housed under specific pathogen-free conditions. In contrast, this activation is not observed in the Lactococcus lactis strain C60; however, when we generate germ-free YC3.60 mice and observe the LAB stimulation of IECs in the absence of gut microbiota, C60 is capable of inducing Ca2+ signaling. This is the first study to successfully visualize the direct effect of probiotics on IECs in live animals. These data strongly suggest that probiotic strains stimulate IECs under physiological conditions, and that their activity is affected by the microenvironment of the small intestine, such as commensal bacteria.

Although it is established that the composition of the human intestinal microbiota changes with age, transition of the intestinal microbiota of animals with age has not been well studied. In the present study, we collected fresh fecal samples from dogs of 5 different age groups (pre-weanling, weanling, young, aged, senile) and analyzed the compositions of their intestinal microbiota with a culture-based method. The results suggested that the composition of the canine intestinal microbiota also changes with age. Among intestinal bacteria predominant in dog intestines, lactobacilli appeared to change with age. Both the number and the prevalence of lactobacilli tended to decrease when dogs became older. Bifidobacteria, on the other hand, was not predominant in the intestine of the dogs. We also identified lactobacilli at the species level based on 16S rRNA gene sequences and found that the species composition of Lactobacillus also changed with age. It was further suggested that bacteria species beneficial to host animals may differ depending on the host species.

Isoflavones contained in the root and flower of Kudzu (Pueraria lobata and related species) are suggested to be the critical component for its effects. Although metabolism of soy isoflavones has been well studied, the composition of isoflavones found in Kudzu is completely different from that of soy isoflavones. In the present study, we investigated whether isoflavones found in the flower of Pueraria thomsonii, a species of Kudzu, were metabolized by human fecal microbiota and murine small intestinal enzymes. Among 5 glycosidic isoflavones of the Pueraria thomsonii flower, tectorigenin 7-O-xylosylglucoside, tectoridin, genistin and glycitin were completely hydrolyzed by a homogenate of germfree mouse small intestine without contribution of bacteria. Released aglycones were not further metabolized, except that up to half of glycitein disappeared. Mouse small intestinal enzymes did not metabolize 6-hydroxygenistein 6,7-di-O-glucoside. Isoflavone aglycones as well as 6-hydroxygenistein 6,7-di-O-glucoside were highly metabolized by most of the human fecal suspensions. Metabolites were not detected with the present analytical methods in most cases. Although further investigations of the pharmacokinetics of Pueraria thomsonii flower isoflavones are needed, the results of the present study indicate active metabolism of Pueraria thomsonii flower isoflavones in the human intestine.

Intestinal microbiota have marked metabolic activity and influences the host in both beneficial and harmful ways. In the present study, we developed an apparatus to measure the amount of CO 2 in the gas excreted during defecation and investigated whether this amount of CO 2 can be used as an indicator of the intestinal environment. The apparatus consists of a fan and a commercial CO 2 sensor attached to a toilet stool. Fecal pH, fecal water content, concentrations of short chain organic acids (SCFAs) and intestinal putrefactive products and composition of fecal microbiota were analyzed as indicators of the intestinal environment. The apparatus could measure the amount of CO 2 in the gas with good reproducibility, irrespective of the open area at the top of the toilet stool, position of gas injection and composition of the gas. In a volunteer study, the amount of C0 2 in defecation gas correlated with pH, water content and concentrations of SCFAs and intestinal putrefactive products in the feces, although correlation with the composition of intestinal microbiota was not be observed. The results indicate that the amount of CO 2 in defecation gas can be measured with simple and sanitary procedures and is a good indicator of the intestinal environment.

BACKGROUND: Few previous reports have considered the effects of dietary fibre on the plasma lipids and caecal enzyme activity of mice fed a rutin-supplemented diet. This investigation studied the effects of pectin on the plasma lipids and caecal enzyme activities of mice fed a diet supplemented with the quercetin glycoside rutin. RESULTS: Male mice were randomly divided into two groups and fed either a pectin–rutin (PR) diet or a cellulose–rutin (CR) diet for 14 days. Plasma cholesterol and triglyceride concentrations and caecal β-glucosidase and β-glucuronidase activities were measured. The plasma cholesterol and triglyceride concentrations were significantly higher in the CR diet group, as were the caecal β-glucosidase and β-glucuronidase activities. The caecal β-glucuronidase/β-glucosidase activity ratio was significantly higher in the PR diet group, indicating differences in the metabolic activity of the intestinal flora. CONCLUSION: The PR diet greatly affected the caecal enzyme activities. A pectin diet supplemented with the quercetin glycoside rutin might affect the lipid metabolism and metabolic activity of the intestinal flora. The plasma lipid-lowering effects of the PR diet might have been partially caused by the metabolic actions of the intestinal gut flora. Copyright © 2009 Society of Chemical Industry

The gut mucosal immune system is crucial in host defense against infection by pathogenic microbacteria and viruses via the production of IgA. Previous studies have shown that intestinal commensal bacteria enhance mucosal IgA production. However, it is poorly understood how these bacteria induce IgA production and which genera of intestinal commensal bacteria induce IgA production effectively. In this study, we compared the immunomodulatory effects of Bacteroides and Lactobacillus on IgA production by Peyer's patches lymphocytes. IgA production by Peyer's patches lymphocytes co-cultured with Bacteroides was higher than with Lactobacillus. In addition, the expression of activation-induced cytidine deaminase increased in co-culture with Bacteroides but not with Lactobacillus. We found that intestinal commensal bacteria elicited IgA production. In particular, Bacteroides induced the differentiation of Peyer's patches B cell into IgA(+) B cells by increasing activation-induced cytidine deaminase expression.

Much attention has focused on the health benefits of isoflavone. Investigating the absorption and metabolism of isoflavonoids is essential for understanding their biological activity. We explored the effect of a high fiber diet containing rice bran hemicellulose on the plasma and cecal isoflavonoids in mice. Mice were fed a 5% rice bran hemicellulose and 5% cellulose-0.1% daidzein diet (RBI diet) or a 5% cellulose-0.1% daidzein diet (CI diet) for 30 days. After the 30-day feeding period, the mice were sacrificed and blood and cecal contents were collected. The plasma isoflavonoids and plasma total cholesterol concentrations were measured. The plasma daidzein concentrations were significantly lower in the RBI group compared to the CI group. In contrast, there were no significant differences in the plasma equol concentrations or plasma total cholesterol concentrations between the RBI and CI groups. Binding affinity against isoflavonoids and/or the bulking effect in the gut might be related with the reduction in plasma daidzein concentration in the RBI group.

Previously, we produced two groups of gnotobiotic mice, GB-3 and GB-4, which showed different responses to Escherichia coli O157:H7 challenge. E. coli O157:H7 was eliminated from GB-3, whereas GB-4 mice became carriers. It has been reported that the lag time of E. coli O157:H7 growth in 50% GB-3 caecal suspension was extended when compared to GB-4 caecal suspension. In this study, competition for nutrients between intestinal microbiota of GB-3 and GB-4 mice and E. coli O157:H7 was examined. Amino acid concentrations in the caecal contents of GB-3 and GB-4 differed, especially the concentration of proline. The supplementation of proline into GB-3 caecal suspension decreased the lag time of E. coli O157:H7 growth in vitro. When E. coli O157:H7 was cultured with each of the strains used to produce GB-3 mice in vitro, 2 strains of E. coli (proline consumers) out of 5 enterobacteriaceae strains strongly suppressed E. coli O157:H7 growth and the suppression was attenuated by the addition of proline into the medium. These results indicate that competition for proline with indigenous E. coli affected the growth of E. coli O157:H7 in vivo and may contribute to E. coli O157:H7 elimination from the intestine.

Previously, we produced two groups of gnotobiotic mice, GB-3 and GB-4, which showed different responses to Escherichia coli O157:H7 challenge. E. coli O157:H7 was eliminated from GB-3, whereas GB-4 became carriers. In this study, we analysed the mechanisms of E. coli O157:H7 elimination using GB-3 and GB-4. When GB-3 and GB-4 mice were challenged with E. coli O157:H7, the E. coli O157:H7 population was reduced in the caecum of GB-3 when compared to that in the GB-4 caecum, although the numbers of E. coli O157:H7 in the small intestine were not significantly different between these two groups of gnotobiotic mice. The lag time of E. coli O157:H7 growth in a 50% GB-3 caecal suspension increased when compared to that in a GB-4 caecal suspension. Acetate and lactate were detected in the GB-3 caecal contents, and acetate and propionate in those from GB-4. Although E. coli O157:H7 growth was not suppressed when it was cultured in anaerobic broth supplemented with these organic acids, the motility of E. coli O157:H7 was suppressed when it was cultured on semi-solid agar supplemented with the combination of acetate and lactate. These results indicate that the organic acid profile in the caecum is an important factor related to the elimination of E. coli O157:H7 from the intestine.