A combined nutrient and lactulose challenge test allows symptom-based clustering of patients with irritable bowel syndrome.

OBJECTIVES: The aim of the present pilot study was to evaluate the usefulness of a test meal containing lactulose in the non-invasive assessment of visceral sensitivity in irritable bowel syndrome (IBS), and to identify subsets of IBS patients based on gastrointestinal (GI) symptom generation. METHODS: We included 43 patients with IBS (Rome III) and 29 healthy controls. The fasted subjects were served three test meals consisting of a 400-ml liquid breakfast alone or containing lactulose (15 or 25 g) in a double-blind crossover design. Seven GI symptoms, overall digestive comfort, and exhaled H2/CH4 were assessed at baseline and every 15 min during 4 h after meal intake. Anxiety and depression were assessed only at baseline. A mapping of the seven GI symptoms was done using a Principal Component Analysis (4 h mean area under the curve, AUC). Independently, a hierarchical cluster analysis was performed on the same parameters to identify GI symptom-based IBS clusters. RESULTS: All three tests were well tolerated. The 25 g lactulose challenge enabled discrimination of IBS from healthy controls according to the symptom response. This challenge also enabled clustering of IBS subjects in two subgroups based mainly on bloating, distension, and discomfort symptoms (2,457 (2,043-2,872), 2,450 (1,910-2,990), 2,602 (2,126-3,079) vs. 537 (383-691), 619 (458-780), 643 (432-854); 4 h mean AUC; P<0.0001), overall digestive comfort (1807 (1318-2295) vs. 3350 (2942-3758); 4 h mean AUC; P<0.0001), and anxiety at baseline (9.2 (7.0-11.5) vs. 5.5 (4.2-6.9); Hospital Anxiety and Depression scale anxiety mean scores; P=0.003). This clustering was independent of the Rome III subtype and the amount of exhaled H2/CH4. CONCLUSIONS: The lactulose challenge test seems to be a promising tool to assess visceral sensitivity in IBS, and to subgroup IBS patients based on their symptom pattern.

Comparison of thermal and chemical enhanced recovery of DNAPL in saturated porous media: 2D tank pumping experiments and two-phase flow modelling.

Pumping experiments were performed in a 2D tank in order to estimate the recovery yield of pure heavy chlorinated organic compounds (DNAPL; dense non-aqueous phase liquids) by varying different parameters: permeability of the saturated zone, pumping flow rates, addition of surfactant and heating. Surfactant was added to decrease capillary forces involved in the entrapment of DNAPL in porous media while temperature was increased to reduce DNAPL viscosity (and hence increase its mobility). Chemical enhancement was performed with the addition of Sodium Dodecyl Benzene Sulfonate (SDBS) (at its Critical Micelle Concentration, to avoid DNAPL dissolution) and thermal enhancement was performed at 50 °C (to avoid DNAPL volatilization). The experiments were monitored with photography allowing, on the basis of image interpretation, to convert optical densities (OD) into water saturations (Sw). Image interpretations were compared with modelling results. The two-phase flow modelling was performed with the pressure-pressure formulation using capillary pressure and relative permeability functions based on the van Genuchten-Mualem equations. Measured volumes of DNAPL recovered as well as the displacement of the DNAPL-water interface (radius and height of the cone of depression) are consistent with the modelling results. Furthermore, chemical enhancement results in a significant increase in the recovery rates of DNAPL. The observed improvement in the recovery of DNAPL with chemical enhancement is due to the fact that: (i) the residual saturation inside the cone of depression is lower and (ii) the cone of depression radius and height increase. Thermal enhancement had no beneficial effect on DNAPL recovery rate or yield. This study shows that it is possible to accurately determine water and DNAPL saturations by image interpretation during pumping tests in a 2D tank in the laboratory. For field-scale applications, the two-phase flow model allows to determine remediation yields as well as the volumes of the cone of depression according to the different operating conditions.

Thermal and chemical enhanced recovery of heavy chlorinated organic compounds in saturated porous media: 1D cell drainage-imbibition experiments.

Chemical and thermal enhanced recovery of pure heavy chlorinated organic compounds (DNAPL; dense non-aqueous phase liquids) was investigated by using lab-scale 1D cells. Temperature was increased to reduce DNAPL viscosity (and hence increase its mobility), while surfactant was added to decrease capillary forces involved in the entrapment of DNAPL in porous media. Laboratory scale experiments, based on mass balance and indirect monitoring methods (i.e., permittivity, electrical resistivity and optical density), were conducted to quantify the effects of these enhancements. Heating the DNAPL up to 50 °C decreased its viscosity by a factor of two. The addition of a surfactant; i.e., Sodium Dodecyl Benzene Sulfonate (SDBS), at its Critical Micelle Concentration (to prevent DNAPL solubilization), decreased interfacial tensions by a factor of 12. Drainage-imbibition experiments performed in 1D cells provided retention curves (capillary pressure as a function of water saturation) of a two-phase (DNAPL-water) system in experimental glass bead porous media. The observed reduction of residual saturation (Srn) obtained with SDBS was 28% for 0.5 mm-diameter glass beads (GB) and 46% for 0.1 mm GB. No significant decrease in Sm was observed with thermal enhancement. The van Genuchten - Mualem model was found to satisfactorily reproduce the measured retention curves. Indirect measurements of water saturations (Sw) showed that: i. measured permittivities were very close to values modeled with the Complex Refractive Index Model (CRIM); ii. Archie's Law was less successful in reproducing measured electrical resistivities; iii. optical densities provide accurate estimations of Sw. At field scale, the combined monitoring of electrical resistivity (which provides a global picture) and permittivity (which yields locally precise but spatially limited information) is expected to significantly improve the collection of information on residual saturations Srn.

Process-based analysis of waste management systems: a case study.

This paper presents an analysis, using process simulation, of the waste management system applied in a collection basin located in the south of Paris (France). The study was conducted in close cooperation with the "SYCTOM of Paris agglomeration", an operator in charge of managing 2.5 milliontons/yr of municipal solid waste in the Paris area. The analysis includes a description of the current situation of waste management in this collection basin, the construction and calibration of a simulator that reproduces this situation, the simulation of scenarios that account for possible future changes in waste flows and treatment options and finally a comparison of scenario results. Results illustrate the interest of a process-based approach to waste management systems. Such an approach is complementary to life cycle analyses, which usually rely on more generic descriptions of waste treatment units. The detailed analysis of a waste management system using local data on waste streams and treatment units provides technical indicators of system efficiency expressed in terms of recycling rates, energy recovery, emission fluxes and costs. Such information can help reach a consensus with respect to the actual situation of waste management and provides decision-makers with quantitative arguments that can be brought into the public debate.

Multiple-scale dynamic leaching of a municipal solid waste incineration ash.

Predicting the impact on the subsurface and groundwater of a pollutant source, such as municipal solid waste (MSW) incineration ash, requires a knowledge of the so-called "source term". The source term describes the manner in which concentrations in dissolved elements in water percolating through waste evolve over time, for a given percolation scenario (infiltration rate, waste source dimensions, etc.). If the source term is known, it can be coupled with a model that simulates the fate and transport of dissolved constituents in the environment of the waste (in particular in groundwater), in order to calculate potential exposures or impacts. The standardized laboratory upward-flow percolation test is generally considered a relevant test for helping to define the source term for granular waste. The LIMULE project (Multiple-Scale Leaching) examined to what extent this test, performed in very specific conditions, could help predict the behaviour of waste at other scales and for other conditions of percolation. Three distinct scales of percolation were tested: a laboratory upward-flow percolation column (30 cm), lysimeter cells (1-2 m) and a large column (5 m) instrumented at different depths. Comparison of concentration data collected from the different experiments suggests that for some non-reactive constituents (Cl, Na, K, etc.), the liquid versus solid ratio (L/S) provides a reasonable means of extrapolating from one scale to another; if concentration data are plotted versus this ratio, the curves coincide quite well. On the other hand, for reactive elements such as chromium and aluminium, which are linked by redox reactions, the L/S ratio does not provide a means of extrapolation, due in particular to kinetic control on reactions. Hence extrapolation with the help of coupled chemistry-transport modelling is proposed.

Effect of a fermented milk containing Bifidobacterium animalis DN-173 010 on the health-related quality of life and symptoms in irritable bowel syndrome in adults in primary care: a multicentre, randomized, double-blind, controlled trial.

BACKGROUND: Health-related quality of life (HRQoL) has been rarely evaluated as a primary endpoint in the assessment of the effect of probiotics on the irritable bowel syndrome (IBS). AIM: To study the effects of fermented milk containing Bifidobacterium animalis DN-173 010 and yoghurt strains on the IBS in a multicentre, double-blind, controlled trial. METHODS: A total of 274 primary care adults with constipation-predominant IBS (Rome II) were randomized to consume for 6 weeks either the test fermented milk or a heat-treated yoghurt (control). HRQoL and digestive symptoms were assessed after 3 and 6 weeks on an intention-to-treat population of 267 subjects. RESULTS: The HRQoL discomfort score, the primary endpoint, improved (P < 0.001) in both groups at weeks 3 and 6. The responder rate for the HRQoL discomfort score was higher (65.2 vs. 47.7%, P < 0.005), as was the decrease in bloating score [0.56 +/- (s.d.)1.01 vs. 0.31 +/- 0.87, P = 0.03], at week 3 in the test vs. the control group. In those subjects with <3 stools/week, stool frequency increased (P < 0.001) over 6 weeks in the test vs. control group. CONCLUSIONS: This study suggests a beneficial effect of a probiotic food on discomfort HRQoL score and bloating in constipation-predominant IBS, and on stool frequency in subjects with <3 stools/week.

The Intestinal Gas Questionnaire: development of a new instrument for measuring gas-related symptoms and their impact on daily life.

BACKGROUND: Although gas-related symptoms (GRS) are common and intrusive, there are no questionnaires to quantitate this problem. This study aimed to develop an instrument to rectify this gap in our knowledge. METHODS: Concepts were initially identified from the literature and interviews with gastroenterologists. Exploratory one-to-one interviews and focus groups with irritable bowel syndrome (IBS) patients (n = 28) and non-IBS subjects (n = 27) with GRS were conducted in UK, France, and Spain leading to a conceptual framework for the questionnaire. Last, iterative rounds of cognitive debriefing were performed with IBS (n = 16) and non-IBS subjects (n = 14). KEY RESULTS: From the first three steps, nine GRS (bloating, distension, flatulence, odorous flatulence, difficult gas evacuation, stomach rumbling, belching, bad breath, and abdominal movement) were identified although abdominal movement was subsequently excluded. Twelve quality of life domains affected by these symptoms were identified as: Clothing, emotional, physical appearance, diet, daily living, work, social life, physical activity, relationships, sex life, sleep, and cognitive function. A 24-h recall for symptoms and a 7-day recall for impact assessment were supported by the qualitative findings. Cognitive debriefing confirmed the understanding of the instrument. Across the three languages, the instrument was conceptually and linguistically consistent. CONCLUSIONS & INFERENCES: The International Gas Questionnaire is a 2-part instrument, developed rigorously and simultaneously in three languages assessing seven symptoms (17 items) and their impact on 12 domains (26 items) in IBS and general population. It is now undergoing psychometric validation and should provide a unique tool for epidemiological surveys and clinical trials for developing new treatments for these symptoms.

Liver subcellular fractions from rats treated by organosulfur compounds from Allium modulate mutagen activation.

The effects of in vivo administration of naturally occurring organosulfur compounds (OSCs) from Allium species were studied on the activation of several mutagens. Male SPF Wistar rats were given p.o. one of either diallyl sulfide (DAS), diallyl disulfide (DADS), dipropyl sulfide (DPS) or dipropyl disulfide (DPDS) during 4 consecutive days and the ability of hepatic S9 and microsomes from treated rats to activate benzo[a]pyrene (BaP), cyclophosphamide (CP), dimethylnitrosamine (DMN), N-nitrosopiperidine (N-PiP) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was determined in the Ames test. Administration of DAS, DPS and DPDS resulted in a significant increase of the activation of BaP, CP, N-PiP and PhIP mediated by S9 and microsomes while DADS treatment only increased the mutagenicity of PhIP. In contrast, S9 from DADS-treated rats significantly inhibited the mutagenicity of N-PiP and BaP. DAS, DADS and DPS strongly inhibited DMN mutagenicity while DPDS enhanced it. To understand the mechanisms underlying these effects, the modifications of the activities of specific isozymes of CYP involved in the activation of these mutagens were studied. DAS, DPS and DPDS strongly enhanced pentoxyresorufin O-dealkylase (PROD) activity related to CYP2B and slightly increased ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities related to CYP1A family. DADS exerted the same effects than other OSCs but to a lesser extent. p-Nitrophenol hydroxylase (PNPH) activity related to CYP2E1 was inhibited by DAS and DADS, whereas DPDS significantly increased this activity. Hence, the effects of OSCs on the mutagenicity of several genotoxic compounds are mediated by modification (enhancement or inhibition) of specific CYP involved in their activation.

Antimutagenic activity of organosulfur compounds from Allium is associated with phase II enzyme induction.

In a previous study, we showed that naturally occurring organosulfur compounds (OSCs) from garlic and onion modulated the activation of carcinogen via the alteration of cytochromes P450. The present study was undertaken to determine the incidence of the in vivo induction of phase II enzymes by individual OSCs on the genotoxicity of several carcinogens. Diallyl sulfide (DAS), diallyl disulfide (DADS), dipropyl sulfide (DPS) and dipropyl disulfide (DPDS), were administered by gavage (1mmol/kg) to male SPF Wistar rats for 4 consecutive days. The effects of treatments on phase II enzymes and on the genotoxicity of carcinogens were evaluated with hepatic cytosols and microsomes from OSCs-treated rats. DADS strongly increased all the phase II enzymes activities examined, i.e. total glutathione S-transferase (GST) activity, mu GST activity, quinone reductase (QR) activity and epoxide hydrolase (EH) activity. In addition, DADS strongly increased the protein level of rGSTP1. QR activity, total and mu GST activities were also increased by DAS and DPDS whereas DPS increased only mu GST activity and QR activity. To assess the repercussions of these inductions on the genotoxicity of carcinogens, the effects of cytosols or microsomes from OSCs-treated rats on the mutagenicity of (+)-anti-7beta,8alpha-dihydroxy-9alpha,10alpha-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), styrene oxide (SO) and 4-nitroquinoline 1-oxide (4-NQO) were measured in the Ames test. DADS showed a very effective antimutagenic activity against BPDE, SO and 4-NQO. DAS reduced the mutagenicity of BPDE and SO. In contrast, DPS and DPDS showed little efficient antimutagenic activity since they only reduced the mutagenicity of BPDE and 4-NQO, respectively. Interestingly, DADS appeared to be as effective as ethoxyquin, a model inducer of phase II enzymes, in both inducing phase II enzymes and inhibiting the mutagenicity of carcinogens. This study demonstrated that the antimutagenic activities of OSCs against several ultimate carcinogens were closely related to their ability to induce phase II enzymes.

Post-initiation modulating effects of allyl sulfides in rat hepatocarcinogenesis.

Effects of administration of diallyl sulfide (DAS) and diallyl disulfide (DADS) on the promotion stage of hepatocarcinogenesis were investigated in rats using the Ito model. They were compared with those of phenobarbital (PB), a well-known liver promoter in rats. Initiation was induced by a single dose of N-nitrosodiethylamine (NDEA) and 3 weeks later, a partial hepatectomy was conducted. Two weeks after the NDEA injection, rats received either 0.05% allyl sulfides, PB or both in their diet for 8 weeks. Feeding with DAS increased the number of liver preneoplastic foci by 63% with respect to the untreated group. However, rats fed DAS showed a lower foci development than rats fed PB. The DADS group did not differ from control group for any of the measured morphometric parameters. Simultaneous administration of DADS with PB partially reduced the promotional activity of PB whereas DAS co-treatment did not modify PB properties. These findings confirm that DAS can act as a promoter in rat liver but exerts no co-promoting effect. Conversely, DADS was found to have promotion-inhibiting ability, suggesting that DADS has greater value than DAS as a chemopreventive agent.

On the hydro-dispersive equivalence between multi-layered mineral barriers.

In the context of municipal solid waste and hazardous waste disposal, the notion of "equivalence" between different barrier designs appears in regulatory documents from several industrialized countries. While in the past, equivalence has been thought of mainly in terms of contaminant travel times, in recent years it has been defined more in terms of the magnitude of a disposal site's potential impact on groundwater resources. This paper presents some original analytical solutions to the problem of contaminant migration through a multi-layered mineral barrier. The solutions account for the two major mechanisms of subsurface contaminant migration, namely, advection and diffusion-dispersion. An example application using the proposed solutions and a numerical model illustrates how one multi-layered mineral barrier can be considered superior to another from a strictly hydro-dispersive viewpoint. The influence of partial saturation of the mineral barrier is investigated using a numerical solution to the Richards equation for unsaturated flow. It is emphasized that conclusions relative to the superiority of one multi-layered barrier, with respect to another, should not only consider hydro-dispersive aspects, but also other processes such as the mechanical and chemical evolutions of the different barrier components. Although such phenomena are poorly addressed by existing models, failure to take them into account, at least in a qualitative fashion, may lead to unconservative conclusions with respect to barrier equivalence.

Chemical changes and leachate mass balance of municipal solid waste bottom ash submitted to weathering.

A study on the chemical stability of municipal solid waste (MSW) bottom ash submitted to weathering was carried out in order to identify and quantify the physico-chemical maturation mechanisms in a large heap (375 tonnes) over a period of about 18 months. The mineralogy and chemical composition of MSW bottom ash were analysed on fresh and maturated material. Calcite is the predominant newly formed mineral during bottom ash maturation, combined with aluminium hydroxides and various sulphates. Lead and zinc are trapped primarily by newly formed carbonates. Monitoring of the pore water and the outlet leachates revealed a marked contrast in the physico-chemical conditions within the heap and at the outlet. The salinity of the fluids peaked at around 16 g/l within the first few weeks and then progressively decreased to fluctuate between 5 and 8 g/l. Due to the high pH of the pore water, the average concentrations of heavy metals in the heap are high: 42.7, 9.6 and 0.8 mg/l for Cu, Pb and Zn. At the heap outlet, however, the leachates are buffered by carbonate precipitation due to equilibration with atmospheric CO2. Copper complexed as a chloride at the outlet remains at a relatively high concentration (10.2 mg/l), whereas Pb and Zn concentrations are below the limit of detection (<25 microg/l). A mass balance carried out over the 18 months of monitoring indicated that 86% of remobilized material within the heap is evacuated from the system. Within the heap, carbonation trapped 43 and 54% of the calcium and bicarbonate flux. The copper, lead and zinc flux at the heap outlet represent only 34, 18 and 19% of the actual remobilized mass of heavy metals.

Effect of a low-flatulogenic diet in patients with flatulence and functional digestive symptoms.

BACKGROUND: Diets rich in fermentable residues increase intestinal gas production. Our aim was to demonstrate the potential effects of diet on gas-related symptoms. METHODS: The effect of a low-flatulogenic test diet (restricted to foodstuffs low in fermentable residues; n = 15) was compared to that of a balanced control diet (Mediterranean type; n = 15) in 30 patients complaining of flatulence and other abdominal symptoms using a randomized parallel design. The following outcomes were measured daily: number of anal gas evacuations by an event marker, severity of gas-related symptoms by 0-10 scales, and sensation of digestive comfort by a -5 (unpleasant) to +5 (pleasant) scale. Measurements were taken pretreatment for 3 days on their habitual diet and for 7 days during the treatment phase. KEY RESULTS: No pretreatment differences were detected between patients allocated to the control or test diets. The test diet significantly reduced the number of gas evacuations (by 54 ± 10%; p = 0.002 vs basal diet) whereas the control diet had a lesser effect (reduction by 28 ± 9%; p = 0.059 vs basal diet; p = 0.089 vs test diet). Compared to the control diet, the test diet significantly reduced flatulence (by 48 ± 7% vs 27 ± 8%, respectively; p = 0.018), abdominal distension (by 48 ± 4% vs 22 ± 12%, respectively; p = 0.038), and enhanced digestive well-being (by 149 ± 18% vs 58 ± 22%, respectively; p = 0.006). CONCLUSIONS & INFERENCES: In patients with gas-related symptoms, a low-flatulogenic diet produces immediate beneficial effects with digestive, cognitive, and emotive dimensions. The number of gas evacuations is an objective biological marker of response to dietary treatment.

A randomized, double-blind, controlled study and pooled analysis of two identical trials of fermented milk containing probiotic Bifidobacterium lactis CNCM I-2494 in healthy women reporting minor digestive symptoms.

BACKGROUND: The probiotic fermented milk (PFM) containing Bifidobacterium lactis CNCM I-2494 improved gastrointestinal (GI) well-being and digestive symptoms in a previous trial involving women reporting minor digestive symptoms. Our objective is to confirm these findings in a second study and in a pooled analysis of both studies. METHODS: In this double-blind, controlled, parallel design study, subjects without diagnosed GI disorders consumed PFM or control dairy product daily for 4 weeks. Endpoints comprised weekly assessment of GI well-being (primary endpoint), rate of responders and digestive symptoms. Data were analyzed on full analysis set population (n = 324) and on the pooled data of randomized subjects of this study with those of the first study (n = 538). KEY RESULTS: In this second study, no significant difference was observed in the percentage of women reporting an improvement in GI well-being [OR = 1.20 (95% CI 0.87, 1.66)] and rate of responders [OR = 1.38 (95% CI 0.89, 2.14)]. Composite score of digestive symptoms was significantly (P < 0.05) reduced in PFM when compared to the control group [LSmean = -0.42 (95% CI -0.81, -0.03)]. In the pooled analysis, significant differences were observed in favor of PFM group for all endpoints: percentage of women with improved GI well-being [OR = 1.36 (95% CI 1.07, 1.73)], rate of responders [OR = 1.53 (95% CI 1.09, 2.16)] and composite score of digestive symptoms [LSmean = -0.48 (95% CI -0.80, -0.16)]. CONCLUSIONS & INFERENCES: This second study did not confirm improvement on the primary endpoint. However, a pooled analysis of the two trials showed improvement in GI well-being and digestive symptoms in women reporting minor digestive symptoms.

Mineralogy and pore water chemistry of a boiler ash from a MSW fluidized-bed incinerator.

This paper presents an investigation of the mineralogy and pore water chemistry of a boiler ash sampled from a municipal solid waste fluidized-bed incinerator, subject to 18 months of dynamic leaching in a large percolation column experiment. A particular focus is on the redox behaviour of Cr(VI) in relation to metal aluminium Al(0), as chromium may represent an environmental or health hazard. The leaching behaviour and interaction between Cr(VI) and Al(0) are interpreted on the basis of mineralogical evolutions observed over the 18-month period and of saturation indices calculated with the geochemical code PhreeqC and reviewed thermodynamic data. Results of mineralogical analyses show in particular the alteration of mineral phases during leaching (e.g. quartz and metal aluminium grains), while geochemical calculations suggest equilibria of percolating fluids with respect to specific mineral phases (e.g. monohydrocalcite and aluminium hydroxide). The combination of leaching data on a large scale and mineralogical analyses document the coupled leaching behaviour of aluminium and chromium, with chromium appearing in the pore fluids in its hexavalent and mobile state once metal aluminium is no longer available for chromium reduction.

Clinical trial: the effects of a fermented milk product containing Bifidobacterium lactis DN-173 010 on abdominal distension and gastrointestinal transit in irritable bowel syndrome with constipation.

BACKGROUND: A sensation of abdominal swelling (bloating) and actual increase in girth (distension) are troublesome features of irritable bowel syndrome (IBS), which is more common in patients with constipation, especially those with delayed transit. AIM: To establish whether a fermented dairy product containing Bifidobacterium lactis DN-173 010 reduces distension in association with acceleration of gastrointestinal transit and improvement of symptoms in IBS with constipation. METHODS: A single centre, randomized, double-blind, controlled, parallel group study in which patients consumed the test product or control product for 4 weeks. Distension, orocaecal and colonic transit and IBS symptoms were assessed on an intention-to-treat population of 34 patients. RESULTS: Compared with control product, the test product resulted in a significant reduction in the percentage change in maximal distension [median difference - 39%, 95% CI (-78, -5); P = 0.02] and a trend towards reduced mean distension during the day [-1.52 cm (-3.33, 0.39); P = 0.096]. An acceleration of orocaecal [-1.2 h (-2.3,0); P = 0.049] as well as colonic [-12.2 h (-22.8, -1.6); P = 0.026] transit was observed and overall symptom severity [-0.5 (-1.0, -0.05); P = 0.032] also improved. CONCLUSIONS: This probiotic resulted in improvements in objectively measured abdominal girth and gastrointestinal transit, as well as reduced symptomatology. These data support the concept that accelerating transit is a useful strategy for treating distension.

Construction and growth properties of a yeast strain defective in sterol 14-reductase.

We have transformed Saccharomyces cerevisiae with a genomic library contained in the replicative vector pFL44. The resulting transformants were screened for resistance to fenpropidin, a specific inhibitor of sterol 14-reductase. A plasmid was isolated that transformed yeast both to resistance to fenpropidin and to an increased specific activity of sterol 14-reductase. Sterol analysis of transformed cells grown in the presence of increasing concentrations of the inhibitor confirmed that resistance was a consequence of over-production of sterol 14-reductase. By chromosomal gene disruption, we have, for the first time, constructed yeast strains defective in sterol 14-reductase. As expected, since yeast in unable to take up sterols in aerobiosis, the disrupted strains do not grow in the presence of oxygen, even if exogenous sterols are supplied. However, disrupted cells grow in anaerobiosis with exogenous oleic acid and ergosterol supplements. They also grow in aerobiosis if they bear an additional mutation allowing sterol uptake. In this last growth condition the cells require a "sparking" ergosterol supplementation (25 nM) and accumulate ignosterol (ergosta-8,14-dienol) as the end-product of the sterol pathway. These results reveal that ignosterol is not obviously toxic to yeast membranes and strongly suggest that the molecular basis of the antifungal-activity morpholine and piperidine is directly related to the specific inhibition of ergosterol formation.

The Saccharomyces cerevisiae mevalonate diphosphate decarboxylase is essential for viability, and a single Leu-to-Pro mutation in a conserved sequence leads to thermosensitivity.

The mevalonate diphosphate decarboxylase is an enzyme which converts mevalonate diphosphate to isopentenyl diphosphate, the building block of isoprenoids. We used the Saccharomyces cerevisiae temperature-sensitive mutant defective for mevalonate diphosphate decarboxylase previously described (C. Chambon, V. Ladeveve, M. Servouse, L. Blanchard, C. Javelot, B. Vladescu, and F. Karst, Lipids 26:633-636, 1991) to characterize the mutated allele. We showed that a single change in a conserved amino acid accounts for the temperature-sensitive phenotype of the mutant. Complementation experiments were done both in the erg19-mutated background and in a strain in which the ERG19 gene, which was shown to be an essential gene for yeast, was disrupted. Epitope tagging of the wild-type mevalonate diphosphate decarboxylase allowed us to isolate the enzyme in an active form by a versatile one-step immunoprecipitation procedure. Furthermore, during the course of this study, we observed that a high level of expression of the wild-type ERG19 gene led to a lower sterol steady-state accumulation compared to that of a wild-type strain, suggesting that this enzyme may be a key enzyme in mevalonate pathway regulation.

Method for rapid purification of class IIa bacteriocins and comparison of their activities.

A three-step method was developed for the purification of mesentericin Y105 (60% yield) from the culture supernatant of Leuconostoc mesenteroides Y105. The same procedure was successfully applied to the purification of five other anti-Listeria bacteriocins identified by mass spectrometry. Specific activities of the purified bacteriocins were compared.

Modulation of phase II enzymes by organosulfur compounds from allium vegetables in rat tissues.

The naturally occurring organosulfur compounds (OSCs) diallyl sulfide (DAS), diallyl disulfide (DADS), dipropyl sulfide (DPS), and dipropyl disulfide (DPDS) were studied with respect to their effects on hepatic, intestinal, renal, and pulmonary phase II drug metabolizing enzymes, i.e., glutathione S-transferase (GST), microsomal epoxide hydrolase (mEH), quinone reductase (QR), and UDP-glucuronosyltransferase (UGT). OSCs were administered po to male SPF Wistar rats. In addition to assays of total enzyme activity, the ability of OSCs to modify the levels of mEH and rGSTA1/A2, A3/A5, M1, M2, and P1 was assessed by Western blotting. Remarkably, DADS significantly increased all Phase II enzyme activities, except the pulmonary mEH. It was noteworthy that only DADS induced QR activity. DAS, DPS, and DPDS induced mEH, GST, and UGT activities in the liver. Interestingly, DAS, DPS, and DPDS significantly decreased renal GST activity. In the same manner, DAS, DPS, and DPDS decreased rGSTA1/A2 and A3/A5 levels in the kidney. Conversely, all OSCs were able to induce GST of alpha and mu classes in the liver. In the intestine, DADS and DAS increased rGSTA1/A2, M2, and P1, while rGSTA3/A5 and M2 were only increased by DADS. In addition, DADS induced rGSTP1 dramatically in the four tissues analyzed. DADS also increased the mEH levels in the liver, intestine, and kidney, while DAS and DPS moderately induced mEH level in the liver. This study brings additional insights into the effects of OSCs on Phase II enzymes and suggests that DADS could be a promising chemopreventive agent considering its pleiotropic capacity of induction.