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Open Access Publications from the University of California

Scholarly Works (9 results)

  • Article
  • Peer Reviewed
UC Davis Previously Published Works (2023)

Background

Bifidobacteria represent an important gut commensal in humans, particularly during initial microbiome assembly in the first year of life. Enrichment of Bifidobacterium is mediated though the utilization of human milk oligosaccharides (HMOs), as several human-adapted species have dedicated genomic loci for transport and metabolism of these glycans. This results in the release of fermentation products into the gut lumen which may offer physiological benefits to the host. Synbiotic pairing of probiotic species with a cognate prebiotic delivers a competitive advantage, as the prebiotic provides a nutrient niche.

Methods

To determine the fitness advantage and metabolic characteristics of an HMO-catabolizing Bifidobacterium strain in the presence or absence of 2'-fucosyllactose (2'-FL), conventionally colonized mice were gavaged with either Bifidobacterium pseudocatenulatum MP80 (B.p. MP80) (as the probiotic) or saline during the first 3 days of the experiment and received water or water containing 2'-FL (as the prebiotic) throughout the study.

Results

16S rRNA gene sequencing revealed that mice provided only B.p. MP80 were observed to have a similar microbiota composition as control mice throughout the experiment with a consistently low proportion of Bifidobacteriaceae present. Using 1H NMR spectroscopy, similar metabolic profiles of gut luminal contents and serum were observed between the control and B.p. MP80 group. Conversely, synbiotic supplemented mice exhibited dramatic shifts in their community structure across time with an overall increased, yet variable, proportion of Bifidobacteriaceae following oral inoculation. Parsing the synbiotic group into high and moderate bifidobacterial persistence based on the median proportion of Bifidobacteriaceae, significant differences in gut microbial diversity and metabolite profiles were observed. Notably, metabolites associated with the fermentation of 2'-FL by bifidobacteria were significantly greater in mice with a high proportion of Bifidobacteriaceae in the gut suggesting metabolite production scales with population density. Moreover, 1,2-propanediol, a fucose fermentation product, was only observed in the liver and brain of mice harboring high proportions of Bifidobacteriaceae.

Conclusions

This study reinforces that the colonization of the gut with a commensal microorganism does not guarantee a specific functional output. Video Abstract.
    Cover page: Milk oligosaccharide-driven persistence of Bifidobacterium pseudocatenulatum modulates local and systemic microbial metabolites upon synbiotic treatment in conventionally colonized mice
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2019)
    Background: There is growing evidence to support the beneficial effects of supplementing direct-fed microbials (DFM) on performance, health status, and immune responses of weaned pigs. Therefore, the objective of this study was to investigate dietary supplementation of Bacillus subtilis (DSM 25841) on growth performance, diarrhea, gut permeability and immunity of weaned pigs experimentally infected with a pathogenic F-18 Escherichia coli (E. coli). Results: The F18 E. coli infection reduced (P < 0.05) growth performance and intestinal villi height, whereas increased (P < 0.05) diarrhea and transcellular and paracellular permeability in the jejunum compared with non-challenged control. Supplementation of Bacillus subtilis linearly enhanced average daily gain of E. coli infected pigs from d 0 to 5 post-inoculation (PI) (P < 0.05) and d 0 to 11 PI (P = 0.058). Supplementation of high dose of Bacillus subtilis reduced (P < 0.05) both transcellular and paracellular permeability on d 5 and d 11 PI compared with the E. coli infected pigs fed with control diet. E. coli infection up-regulated (P < 0.05) the mRNA expression of SLC5A10 (soluble carrier family 5 member 10) and MUC2 (mucin 2) on d 5 PI, but down-regulated (P < 0.05) expression of SLC5A10, MUC2, and CLDN1 on d 11 PI in jejunal mucosa when pigs were fed with the control diet. Supplementation of Bacillus subtilis linearly up-regulated (P < 0.05) the mRNA expression of CFTR and ZO1 on d 5 PI and SLC5A10 and MUC2 on d 11 PI in jejunal mucosa of E. coli infected pigs. In addition, E. coli infection increased (P < 0.05) the mRNA expression of several immune genes (IL1A, IL1B, and IL7 on d 5 PI, and IL1B, IL6, IL7, and TNF on d 11 PI) in the ileal mucosa of weaned pigs. Inclusion of Bacillus subtilis to control diet linearly down-regulated gene expression of IL1A on d 5 PI (P = 0.07) and IL6 on d 11 PI (P < 0.05) in ileal mucosa of E. coli infected pigs. Conclusions: Supplementation of Bacillus subtilis (DSM 25841) enhanced growth rate and improved gut barrier function of weaned pigs experimentally infected with a pathogenic E. coli.
      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2019)
      Most of the commercially available β-glucans are derived from yeast, while there are limited research on algae-derived β-glucan in pigs. Therefore, the objective of this experiment was to investigate the influence of dietary supplementation of algae-derived β-glucan on diarrhea, gut permeability, and immune responses of weaned pigs experimentally infected with a pathogenic Escherichia coli (E. coli). Thirty-six weaned pigs (7.69 ± 0.77 kg BW) were individually housed in disease containment rooms and randomly allotted to one of three dietary treatments (n = 12): control diet and 2 additional diets containing either 54 or 108 mg/kg of β-glucan. The experiment lasted 17 d [5 d before and 12 d post inoculation (PI)]. The inoculum used in this experiment was F18 E. coli, containing heat-labile toxin, heat-stable toxin b, and shiga-lie toxin 2. The inoculation doses were 10 10 cfu/3 mL oral dose daily for 3 days. Diarrhea score (1, normal, to 5, watery diarrhea) was recorded for each pig daily to calculate frequency of diarrhea. Blood samples were collected on d 0 before E. coli challenge, and on d 2, 5, 8, and 12 PI to measure total and differential blood cell count in whole blood and several inflammatory markers in serum. Fresh jejunal tissues were collected from 4 pigs in the control group and high dose β-glucan group to analyze gut permeability on d 5 and d 12 PI with Ussing Chamber. Jejunal and ileal mucosa were also collected to measure the mRNA expression of several genes related to gut barrier function and immune responses. Results of this experiment revealed that inclusion of high dose β-glucan reduced (P < 0.05) frequency of diarrhea (29.01% vs. 17.28%) for the entire experimental period. This was likely due to the reduced (P < 0.05) gut permeability and increased (P < 0.05) mRNA expression of gut barrier function genes (Claudin, Occludin, and MUC2) in jejunal mucosa of E. coli challenged pigs as β-glucan supplemented. Supplementation of β-glucan also reduced (P < 0.05) white blood cells, neutrophils, serum tumor necrosis factor (TNF)-α cortisol, and haptoglobin, and down-regulated (P < 0.05) the mRNA expression of several immune genes (IL1B, IL6, and TNFA) in ileal mucosa of E. coli challenged pigs, compared with the control diet. In conclusion, in feed supplementation of algae-derived β-glucan alleviated diarrhea of F18 E. coli infected pigs by enhancing gut integrity. Feeding β-glucan also boosted host immune response against E. coli infection.
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2021)
        Understanding how exogenous microbes stably colonize the animal gut is essential to reveal mechanisms of action and tailor effective probiotic treatments. Bifidobacterium species are naturally enriched in the gastrointestinal tract of breast-fed infants. Human milk oligosaccharides (HMOs) are associated with this enrichment. However, direct mechanistic proof of the importance of HMOs in this colonization is lacking given milk contains additional factors that impact the gut microbiota. This study examined mice supplemented with the HMO 2'fucosyllactose (2'FL) together with a 2'FL-consuming strain, Bifidobacterium pseudocatenulatum MP80. 2'FL supplementation creates a niche for high levels of B.p. MP80 persistence, similar to Bifidobacterium levels seen in breast-fed infants. This synergism impacted gut microbiota composition, activated anti-inflammatory pathways and protected against chemically-induced colitis. These results demonstrate that bacterial-milk glycan interactions alone drive enrichment of beneficial Bifidobacterium and provide a model for tunable colonization thus facilitating insight into mechanisms of health promotion by bifidobacteriain neonates.
          Cover page: Bifidobacterium catabolism of human milk oligosaccharides overrides endogenous competitive exclusion driving colonization and protection
          • Article
          • Peer Reviewed
          ICTS Publications (2017)

          A streamlined transition from inpatient to outpatient care can decrease 30-day readmissions. Outpatient parenteral antibiotic therapy (OPAT) programs have not reduced readmissions; an OPAT bundle has been suggested to improve outcomes. We implemented a transition-of-care (TOC) OPAT bundle and assessed the effects on all-cause, 30-day hospital readmission.

          Retrospectively, patients receiving postdischarge intravenous antibiotics were evaluated before and after implementation of a TOC-OPAT program in Bronx, New York, between July, 2015 and February, 2016. Pearson's χ2test was used to compare 30-day readmissions between groups, and logistic regression was used to adjust for covariates. Time from discharge to readmission was analyzed to assess readmission risk, using log-rank test to compare survival curves and Cox proportional hazards model to adjust for covariates. Secondary outcomes, 30-day emergency department (ED) visits, and mortality were analyzed similarly.

          Compared with previous standard care (n = 184), the TOC-OPAT group (n = 146) had significantly lower 30-day readmissions before (13.0% vs 26.1%,P< .01) and after adjustment for covariates (odds ratio [OR] = 0.51; 95% confidence interval [CI], 0.27-0.94;P= .03). In time-dependent analyses, TOC-OPAT patients were at significantly lower risk for readmission (log-rank test,P< .01; hazard ratio = 0.56; 95% CI, 0.32-0.97;P= .04). Propensity-matched sensitivity analysis showed lower readmissions in the TOC-OPAT group (13.6% vs 24.6%,P= .04), which was attenuated after adjustment (OR = 0.51; 95% CI, 0.25-1.05;P= .07). Mortality and ED visits were similar in both groups.

          Our TOC-OPAT patients had reduced 30-day readmissions compared with the previous standard of care. An effective TOC-OPAT bundle can successfully improve patient outcomes in an economically disadvantaged area.

            Cover page: Bundle in the Bronx: Impact of a Transition-of-Care Outpatient Parenteral Antibiotic Therapy Bundle on All-Cause 30-Day Hospital Readmissions.Creative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UC Davis Previously Published Works (2020)

            Background

            Bifidobacterium longum subsp. infantis (B. infantis) is a commensal bacterium that colonizes the gastrointestinal tract of breast-fed infants. B. infantis can efficiently utilize the abundant supply of oligosaccharides found in human milk (HMO) to help establish residence. We hypothesized that metabolites from B. infantis grown on HMO produce a beneficial effect on the host.

            Results

            In a previous study, we demonstrated that B. infantis routinely dominated the fecal microbiota of a breast fed Bangladeshi infant cohort (1). Characterization of the fecal metabolome of binned samples representing high and low B. infantis populations from this cohort revealed higher amounts of the tryptophan metabolite indole-3-lactic acid (ILA) in feces with high levels of B. infantis. Further in vitro analysis confirmed that B. infantis produced significantly greater quantities of the ILA when grown on HMO versus lactose, suggesting a growth substrate relationship to ILA production. The direct effects of ILA were assessed in a macrophage cell line and intestinal epithelial cell lines. ILA (1-10 mM) significantly attenuated lipopolysaccharide (LPS)-induced activation of NF-kB in macrophages. ILA significantly attenuated TNF-α- and LPS-induced increase in the pro-inflammatory cytokine IL-8 in intestinal epithelial cells. ILA increased mRNA expression of the aryl hydrogen receptor (AhR)-target gene CYP1A1 and nuclear factor erythroid 2-related factor 2 (Nrf2)-targeted genes glutathione reductase 2 (GPX2), superoxide dismutase 2 (SOD2), and NAD(P) H dehydrogenase (NQO1). Pretreatment with either the AhR antagonist or Nrf-2 antagonist inhibited the response of ILA on downstream effectors.

            Conclusions

            These findings suggest that ILA, a predominant metabolite from B. infantis grown on HMO and elevated in infant stool high in B. infantis, and protects gut epithelial cells in culture via activation of the AhR and Nrf2 pathway.
              Cover page: Indole-3-lactic acid associated with Bifidobacterium-dominated microbiota significantly decreases inflammation in intestinal epithelial cells
              • Article
              • Peer Reviewed
              ICTS Publications (2017)

              A streamlined transition from inpatient to outpatient care can decrease 30-day readmissions. Outpatient parenteral antibiotic therapy (OPAT) programs have not reduced readmissions; an OPAT bundle has been suggested to improve outcomes. We implemented a transition-of-care (TOC) OPAT bundle and assessed the effects on all-cause, 30-day hospital readmission.

              Retrospectively, patients receiving postdischarge intravenous antibiotics were evaluated before and after implementation of a TOC-OPAT program in Bronx, New York, between July, 2015 and February, 2016. Pearson's χ2test was used to compare 30-day readmissions between groups, and logistic regression was used to adjust for covariates. Time from discharge to readmission was analyzed to assess readmission risk, using log-rank test to compare survival curves and Cox proportional hazards model to adjust for covariates. Secondary outcomes, 30-day emergency department (ED) visits, and mortality were analyzed similarly.

              Compared with previous standard care (n = 184), the TOC-OPAT group (n = 146) had significantly lower 30-day readmissions before (13.0% vs 26.1%,P< .01) and after adjustment for covariates (odds ratio [OR] = 0.51; 95% confidence interval [CI], 0.27-0.94;P= .03). In time-dependent analyses, TOC-OPAT patients were at significantly lower risk for readmission (log-rank test,P< .01; hazard ratio = 0.56; 95% CI, 0.32-0.97;P= .04). Propensity-matched sensitivity analysis showed lower readmissions in the TOC-OPAT group (13.6% vs 24.6%,P= .04), which was attenuated after adjustment (OR = 0.51; 95% CI, 0.25-1.05;P= .07). Mortality and ED visits were similar in both groups.

              Our TOC-OPAT patients had reduced 30-day readmissions compared with the previous standard of care. An effective TOC-OPAT bundle can successfully improve patient outcomes in an economically disadvantaged area.

                Cover page: Bundle in the Bronx: Impact of a Transition-of-Care Outpatient Parenteral Antibiotic Therapy Bundle on All-Cause 30-Day Hospital Readmissions.Creative Commons 'BY' version 4.0 license
                • Article
                • Peer Reviewed
                UCLA Previously Published Works (2015)
                Tightly regulated Ca(2+) homeostasis is a prerequisite for proper cardiac function. To dissect the regulatory network of cardiac Ca(2+) handling, we performed a chemical suppressor screen on zebrafish tremblor embryos, which suffer from Ca(2+) extrusion defects. Efsevin was identified based on its potent activity to restore coordinated contractions in tremblor. We show that efsevin binds to VDAC2, potentiates mitochondrial Ca(2+) uptake and accelerates the transfer of Ca(2+) from intracellular stores into mitochondria. In cardiomyocytes, efsevin restricts the temporal and spatial boundaries of Ca(2+) sparks and thereby inhibits Ca(2+) overload-induced erratic Ca(2+) waves and irregular contractions. We further show that overexpression of VDAC2 recapitulates the suppressive effect of efsevin on tremblor embryos whereas VDAC2 deficiency attenuates efsevin's rescue effect and that VDAC2 functions synergistically with MCU to suppress cardiac fibrillation in tremblor. Together, these findings demonstrate a critical modulatory role for VDAC2-dependent mitochondrial Ca(2+) uptake in the regulation of cardiac rhythmicity.
                  Cover page: Mitochondrial Ca2+ uptake by the voltage-dependent anion channel 2 regulates cardiac rhythmicity
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2022)

                  Background

                  Cognitive impairment, including dementia, is frequently under-detected in primary care. The Consortium for Detecting Cognitive Impairment, including Dementia (DetectCID) convenes three multidisciplinary teams that are testing novel paradigms to improve the frequency and quality of patient evaluations for detecting cognitive impairment in primary care and appropriate follow-up.

                  Objective

                  Our objective was to characterize the three paradigms, including similarities and differences, and to identify common key lessons from implementation.

                  Methods

                  A qualitative evaluation study with dementia specialists who were implementing the detection paradigms. Data was analyzed using content analysis.

                  Results

                  We identified core components of each paradigm. Key lessons emphasized the importance of engaging primary care teams, enabling primary care providers to diagnose cognitive disorders and provide ongoing care support, integrating with the electronic health record, and ensuring that paradigms address the needs of diverse populations.

                  Conclusion

                  Approaches are needed that address the arc of care from identifying a concern to post-diagnostic management, are efficient and adaptable to primary care workflows, and address a diverse aging population. Our work highlights approaches to partnering with primary care that could be useful across specialties and paves the way for developing future paradigms that improve differential diagnosis of symptomatic cognitive impairment, identifying not only its presence but also its specific syndrome or etiology.
                    Cover page: Lessons from Detecting Cognitive Impairment Including Dementia (DetectCID) in Primary Care.
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