Lactobacillus rhamnosus GG (GG) is a widely used and intensively studied probiotic bacterium. Although the health benefits of strain GG are well documented, the systematic exploration of mechanisms ...by which this strain exerts probiotic effects in the host has only recently been initiated. The ability to survive the harsh conditions of the gastrointestinal tract, including gastric juice containing bile salts, is one of the vital characteristics that enables a probiotic bacterium to transiently colonize the host. Here we used gene expression profiling at the transcriptome and proteome levels to investigate the cellular response of strain GG toward bile under defined bioreactor conditions. The analyses revealed that in response to growth of strain GG in the presence of 0.2% ox gall the transcript levels of 316 genes changed significantly (p < 0.01, t test), and 42 proteins, including both intracellular and surface-exposed proteins (i.e. surfome), were differentially abundant (p < 0.01, t test in total proteome analysis; p < 0.05, t test in surfome analysis). Protein abundance changes correlated with transcriptome level changes for 14 of these proteins. The identified proteins suggest diverse and specific changes in general stress responses as well as in cell envelope-related functions, including in pathways affecting fatty acid composition, cell surface charge, and thickness of the exopolysaccharide layer. These changes are likely to strengthen the cell envelope against bile-induced stress and signal the GG cells of gut entrance. Notably, the surfome analyses demonstrated significant reduction in the abundance of a protein catalyzing the synthesis of exopolysaccharides, whereas a protein dedicated for active removal of bile compounds from the cells was up-regulated. These findings suggest a role for these proteins in facilitating the well founded interaction of strain GG with the host mucus in the presence of sublethal doses of bile. The significance of these findings in terms of the functionality of a probiotic bacterium is discussed.
Acidic environments encountered in food products and during gastrointestinal tract passage affect the survival of bacteria that are marketed as probiotics. In this study, the global proteome ...responses of the probiotic lactic acid bacterium
Lactobacillus rhamnosus GG to two physiologically relevant pH conditions (pH 4.8 and pH 5.8) were studied by 2-D DIGE. The proteomics data were complemented with transcriptome analyses by whole-genome DNA microarrays. The cells were cultured in industrial-type whey medium under strictly defined bioreactor conditions. In total, 2-D DIGE revealed the pH-dependent formation of 92 protein spots. In response to lower pH conditions, the strongest up-regulation of all proteins was detected for a predicted surface antigen, LGG_02016. In addition, the acid pH was found to up-regulate the expression of F
0F
1-ATP synthase genes whereas the abundance of proteins participating in nucleotide biosynthesis and protein synthesis was significantly diminished. Moreover, the results suggest that
L. rhamnosus GG modulates its pyruvate metabolism depending on the growth pH. Furthermore, a growth pH-dependent protein phosphorylation phenomenon was detected in several
L. rhamnosus GG proteins with ProQ Diamond 2-DE gel staining. Proteins participating in central cellular pathways were shown to be phosphorylated, and the phosphorylation of glycolytic enzymes was found to be especially extensive.
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► We studied the response of probiotic
L. rhamnosus GG to acid stress. ► 2-D DIGE revealed pH-dependent production in 65 different proteins. ► The proteomics data were complemented with transcriptome analyses. ► pH-dependent protein phosphorylation was detected in several
L. rhamnosus GG proteins.
The present study reports the identification and comparison of all expressed cell-surface exposed proteins from the well-known probiotic L. rhamnosus GG and a related dairy strain, Lc705. To obtain ...this information, the cell-surface bound proteins were released from intact cells by trypsin shaving under hypertonic conditions with and without DTT. Liquid chromatography tandem mass spectrometry (LC−MS/MS) analyses of the purified peptides identified a total of 102 and 198 individual proteins from GG and Lc705, respectively. Comparison of both data sets suggested that the Msp-type antigens (Msp1, Msp2) and the serine protease HtrA were uniquely exposed at the cell surface of GG, whereas the Lc705-specific proteins included lactocepin and a wider range of different moonlighting proteins. ImmunoEM analyses with the GG and Lc705 antibodies suggested that the whole-cell immunization yielded antibodies toward surface-bound proteins and proteins that were secreted or released from the cell-surface. One of the detected antigens was a pilus-like structure on the surface of GG cells, which was not detected with Lc705 antibodies. Further 2-DE immunoblotting analysis of GG proteins with both L. rhamnosus antisera revealed that majority of the detected antigens were moonlighting proteins with potential roles in adhesion, pathogen exclusion or immune stimulation. The present study provides the first catalog of surface-exposed proteins from lactobacilli and highlights the importance of the specifically exposed moonlighting proteins for adaptation and probiotic functions of L. rhamnosus.
Lactobacillus rhamnosus GG (LGG) is one of the most extensively studied and widely used probiotic bacteria. While the benefits of LGG treatment in gastrointestinal disorders and immunomodulation are ...well-documented, functional genomics research of this bacterium has only recently been initiated. In the present study, a 2-D DIGE approach was used for the quantitative analysis of growth media-dependent changes in LGG protein abundance. Proteins were isolated from cells grown in industrial-type whey-based medium or in rich laboratory medium for subsequent 2-D DIGE. The analysis revealed patterns of protein abundance unique to each growth condition. In total, 196 quantitatively altered protein spots (at least 1.5-fold change in relative abundance, p < 0.05) representing approximately 13% of all protein spots in the gel were detected. From these protein spots, 157 were identified by mass spectrometry and were found to represent 100 distinct gene products. Collectively, these data show that growth of LGG in whey medium increased the relative abundance of proteins involved in purine biosynthesis, galactose metabolism, and fatty acid biosynthesis. In comparison, growth of LGG in laboratory medium resulted in an increase in the amount of proteins involved in translation and the general stress response, as well as pyrimidine and exopolysaccharide biosynthesis. Moreover, several enzymes of the proteolytic system of LGG demonstrated growth medium-dependent production. The present study demonstrates the fundamental effects of culture conditions on the proteome of LGG, which are likely to affect the functionality and characteristics of its use as a probiotic.
Summary
The growth phase during which probiotic bacteria are harvested and consumed can strongly influence their performance as health‐promoting agents. In this study, global transcriptomic and ...proteomic changes were studied in the widely used probiotic Lactobacillus rhamnosus GG during growth in industrial‐type whey medium under strictly defined bioreactor conditions. The expression of 636 genes (P ≤ 0.01) and 116 proteins (P < 0.05) changed significantly over time. Of the significantly differentially produced proteins, 61 were associated with alterations at the transcript level. The most remarkable growth phase‐dependent changes occurred during the transition from the exponential to the stationary growth phase and were associated with the shift from glucose fermentation to galactose utilization and the transition from homolactic to mixed acid fermentation. Furthermore, several genes encoding proteins proposed to promote the survival and persistence of L. rhamnosus GG in the host and proteins that directly contribute to human health showed temporal changes in expression. Our results suggest that L. rhamnosus GG has a highly flexible and adaptable metabolism and that the growth stage during which bacterial cells are harvested and consumed should be taken into consideration to gain the maximal benefit from probiotic bacteria.
Hyvää verkko-opetusta etsimässä Ahteenmäki-Pelkonen, Leena; Kajamaa, Anu; Koponen, Johanna ...
Aikuiskasvatus,
09/2004, Letnik:
24, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Hyvää verkko-opetusta etsimässä : oppimista edistävät ja estävät tekijät verkko-oppimisympäristöissä : opiskelijoiden kokemukset ja opettajien arviot, Anne Nevgi ja Kirsi Tirri, Turku (2003)
The vasoactive-inotropic score (VIS) predicts mortality and morbidity after paediatric cardiac surgery. Here we examined whether VIS also predicted outcome in adults after cardiac surgery, and ...compared predictive capability between VIS and three widely used scoring systems.
This single-centre retrospective cohort study included 3213 cardiac surgery patients. Maximal VIS (VISmax) was calculated using the highest doses of vasoactive and inotropic medications administered during the first 24 h post-surgery. We established five VISmax categories: 0–5, >5–15, >15–30, >30–45, and >45 points. The predictive accuracy of VISmax was evaluated for a composite outcome, which included 30-day mortality, mediastinitis, stroke, acute kidney injury, and myocardial infarction.
VISmax showed good prediction accuracy for the composite outcome area under the curve (AUC), 0.72; 95% confidence interval (CI), 0.69–0.75. The incidence of the composite outcome was 9.6% overall and 43% in the highest VISmax group (>45). VISmax predicted 30-day mortality (AUC, 0.76; 95% CI, 0.69–0.83) and 1-yr mortality (AUC, 0.70; 95% CI, 0.65–0.74). Prediction accuracy for unfavourable outcome was significantly better with VISmax than with Acute Physiology and Chronic Health Evaluation II (P=0.01) and Simplified Acute Physiological Score II (P=0.048), but not with the Sequential Organ Failure Assessment score (P=0.32).
In adults after cardiac surgery, VISmax predicted a composite of unfavourable outcomes and predicted mortality up to 1 yr after surgery.
Our aim was to review recent studies and estimate the rate of cannabis use disorders (CUDs) in schizophrenia, as well as to examine the factors affecting this rate.
We conducted an electronic search ...of 3 literature databases and a manual search of articles from 1996 to 2008. The key words used were "schizophreni*," "psychos*s," "psychotic," "cannabis abuse," "cannabis dependence," "cannabis use disorder," "substance use disorder," "substance abuse," "substance dependence," and "dual diagnosis." Articles that reported diagnoses according to the Diagnostic and Statistical Manual of Mental Disorders or International Classification of Diseases were included. Regression analysis was used to examine how estimated rates of CUDs are affected by various study characteristics such as the classification system, inpatient vs outpatient status, study location, proportion of males, age of the sample, or duration of illness.
Thirty-five studies met our search criteria. The median current rate of CUDs was 16.0% (interquartile range IQR = 8.6-28.6, 10 studies), and the median lifetime rate was 27.1% (IQR = 12.2-38.5, 28 studies). The median rate of CUDs was markedly higher in first-episode vs long-term patients (current 28.6%/22.0%, lifetime 44.4%/12.2%, respectively) and in studies where more than two-thirds of the participants were males than in the other studies (33.8%/13.2%). CUDs were also more common in younger samples than in the others (current 38.5%/16.0%, lifetime 45.0%/17.9%).
Approximately every fourth schizophrenia patient in our sample of studies had a diagnosis of CUDs. CUDs were especially common in younger and first-episode patient samples as well as in samples with a high proportion of males.
The shear rheology of two mechanically manufactured microfibrillated cellulose (MFC) suspensions was studied in a consistency range of 0.2–2.0% with a pipe rheometer combined with ultrasound velocity ...profiling. The MFC suspensions behaved at all consistencies as shear thinning power law fluids. Despite their significantly different particle size, the viscous behavior of the suspensions was quantitatively similar. For both suspensions, the dependence of yield stress and the consistency index on consistency was a power law with an exponent of 2.4, similar to some pulp suspensions. The dependence of flow index on consistency was also a power law, with an exponent of − 0.36. The slip flow was very strong for both MFCs and contributed up to 95% to the flow rate. When wall shear stress exceeded two times the yield stress, slip flow caused drag reduction with consistencies higher than 0.8%. When inspecting the slip velocities of both suspensions as a function of wall shear stress scaled with the yield stress, a good data collapse was obtained. The observed similarities in the shear rheology of both the MFC suspensions and the similar behavior of some pulp fiber suspensions suggests that the shear rheology of MFC suspensions might be more universal than has previously been realized.
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