Altered urinary bladder function in mice lacking the vanilloid receptor TRPV1

In the urinary bladder, the capsaicin-gated ion channel TRPV1 is expressed both within afferent nerve terminals and within the epithelial cells that line the bladder lumen. To determine the significance of this expression pattern, we analyzed bladder function in mice lacking TRPV1. Compared with wild-type littermates, trpv1(-/-) mice had a higher frequency of low-amplitude, non-voiding bladder contractions. This alteration was accompanied by reductions in both spinal cord signaling and reflex voiding during bladder filling (under anesthesia). In vitro, stretch-evoked ATP release and membrane capacitance changes were diminished in bladders excised from trpv1(-/-) mice, as was hypoosmolality-evoked ATP release from cultured trpv1(-/-) urothelial cells. These findings indicate that TRPV1 participates in normal bladder function and is essential for normal mechanically evoked purinergic signaling by the urothelium.

Evaluating the 'Labeled Magnitude Scale' for measuring sensations of taste and smell

The Labeled Magnitude Scale (LMS) is a semantic scale of perceptual intensity characterized by a quasi-logarithmic spacing of its verbal labels. The LMS had previously been shown to yield psychophysical functions equivalent to magnitude estimation (ME) when gustatory, thermal and nociceptive stimuli were presented and rated together, and the upper bound of the LMS was defined as the 'strongest imaginable oral sensation'. The present study compared the LMS to ME within the more limited contexts of taste and smell. In Experiment 1, subjects used both methods to rate either taste intensity produced by sucrose and NaC1 or odor intensity produced by acetic acid and phenyl ethyl alcohol, with the upper bound of the LMS defined as either the 'strongest imaginable taste' or the 'strongest imaginable odor'. The LMS produced psychophysical functions equivalent to those produced by ME. In, Experiment 2 a new group of subjects used both methods to rate the intensity of three different taste qualities, with the upper bound of the LMS defined as the 'strongest imaginable [sweetness, saltiness, or bitterness]'. In all three cases the LMS produced steeper functions than did ME. Experiment 3 tested the hypothesis that the LMS yields data comparable to ME only when the perceptual domain under study includes painful sensations. This hypothesis was supported when the LMS again produced steeper functions that ME after subjects had been explicitly instructed to omit painful sensations (e.g. the 'burn' of hot peppers) from the concept of 'strongest imaginable taste'. We conclude that the LMS can be used to scale sensations of taste and smell when they are broadly defined, but that it should be modified for use in scaling specific taste (and probably odor) qualities. The implications of these results for theoretical issues related to ME, category-ratio scales and the size of the perceptual range in different sensory modalities are discussed.

Saccharomyces cerevisiae commits to a programmed cell death process in response to acetic acid

Recent evidence has revealed the occurrence of an apoptotic phenotype in Saccharomyces cerevisiae that is inducible with oxidative stress. Here, exposure of S. cerevisiae to 20-200 mM acetic acid for 200 min at pH 3.0 resulted in cell death. Yeast mortality induced by 120-200 mM acid was not inhibited by cycloheximide and was accompanied by ultrastructural alterations typical of necrosis. In contrast, alterations associated with cell death induced by 20-80 mM acetic acid included: (i) cycloheximide-inhibitable chromatin condensation along the nuclear envelope; (ii) exposure of phosphatidylserine on the surface of the cytoplasmic membrane, revealed by the FITC-annexin V reaction; and (iii) the occurrence of DNA strand breaks, demonstrated by the TUNEL assay. These results show that a programmed cell death process sharing common features with an apoptotic phenotype can be induced by acetic acid in S. cerevisiae. This observation raises the possibility of this mode of cell death being more generalized in yeasts than previously considered and extended to cell death induced by other stress agents.

Involvement of resident macrophages and mast cells in the writhing nociceptive response induced by zymosan and acetic acid in mice

Intraperitoneal administration of zymosan and acetic acid induced a dose-dependent nociceptive writhing response in mice. Lavage of the peritoneal cavities with saline reduced the number of total resident peritoneal cells and caused a proportional decrease in the nociceptive responses induced by these stimuli. Furthermore, the specific reduction of the peritoneal mast cell population by intraperitoneal administration of compound 48/80 also reduced the nociceptive responses induced by zymosan and acetic acid. In contrast, enhancement of the peritoneal macrophage population by pretreatment of the cavities with thioglycollate caused an increase in the number of writhes induced by both stimuli. These data suggest that the nociceptive responses induced by zymosan and acetic acid are dependent upon the peritoneal resident macrophages and mast cells. These cells modulate the nociceptive response induced by zymosan and acetic acid via release of tumour necrosis factor alpha (TNF-alpha), interleukin 1beta and interleukin 8. This suggestion is supported by the following observations: (a) pretreatment of the peritoneal cavities with antisera against these cytokines reduced the nociceptive responses induced by these stimuli; (b) peritoneal cells harvested from cavities injected with zymosan or acetic acid released both interleukin 1beta and TNF-alpha; (c) although individual injection of TNF-alpha, interleukin 1beta or interleukin 8 did not induce the nociceptive effect, intraperitoneal injection of a mixture of these three recombinant cytokines caused a significant nociceptive writhing response. In conclusion, our results suggest that the nociceptive activity of zymosan and acetic acid in the writhing model is due to the release of TNF-alpha, interleukin 1beta and interleukin 8 by resident peritoneal macrophages and mast cells.

Activation of G protein-coupled receptor 43 in adipocytes leads to inhibition of lipolysis and suppression of plasma free fatty acids

G protein-coupled receptor 43 (GPR43) has been identified as a receptor for short-chain fatty acids that include acetate and propionate. A potential involvement of GPR43 in immune and inflammatory response has been previously suggested because its expression is highly enriched in immune cells. GPR43 is also expressed in a number of other tissues including adipocytes; however, the functional consequences of GPR43 activation in these other tissues are not clear. In this report, we focus on the potential functions of GPR43 in adipocytes. We show that adipocytes treated with GPR43 natural ligands, acetate and propionate, exhibit a reduction in lipolytic activity. This inhibition of lipolysis is the result of GPR43 activation, because this effect is abolished in adipocytes isolated from GPR43 knockout animals. In a mouse in vivo model, we show that the activation of GPR43 by acetate results in the reduction in plasma free fatty acid levels without inducing the flushing side effect that has been observed by the activation of nicotinic acid receptor, GPR109A. These results suggest a potential role for GPR43 in regulating plasma lipid profiles and perhaps aspects of metabolic syndrome.

Apoptosis induced by environmental stresses and amphotericin B in Candida albicans

New antifungal agents are urgently required to combat life-threatening infections caused by opportunistic fungal pathogens like Candida albicans. The manipulation of endogenous fungal programmed cell death responses could provide a basis for future therapies. Here we assess the physiology of death in C. albicans in response to environmental stresses (acetic acid and hydrogen peroxide) and an antifungal agent (amphotericin B). Exposure of C. albicans to 40-60 mM acetic acid, 5-10 mM hydrogen peroxide, or 4-8 microg.ml-1 amphotericin B produced cellular changes reminiscent of mammalian apoptosis. Nonviable cells that excluded propidium iodide displayed the apoptotic marker phosphatidylserine (as shown by annexin-V-FITC labeling), were terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL)-positive (indicating nuclease-mediated double-strand DNA breakage), and produced reactive oxygen species. Ultrastructural changes in apoptotic cells included chromatin condensation and margination, separation of the nuclear envelope, and nuclear fragmentation. C. albicans cells treated at higher doses of these compounds showed cellular changes characteristic of necrosis. Necrotic cells displayed reduced TUNEL staining, a lack of surface phosphatidylserine, limited reactive oxygen species production, and an inability to exclude propidium iodide. Necrotic cells lacked defined nuclei and showed extensive intracellular vacuolization. Apoptosis in C. albicans was associated with an accumulation of cells in the G2/M phase of the cell cycle, and under some apoptosis-inducing conditions, significant proportions of yeast cells switched to hyphal growth before dying. This is a demonstration of apoptosis in a medically important fungal pathogen.

Main and interaction effects of acetic acid, furfural, and p-hydroxybenzoic acid on growth and ethanol productivity of yeasts

The influence of the factors acetic acid, furfural, and p-hydroxybenzoic acid on the ethanol yield (YEtOH) of Saccharomyces cerevisiae, bakers' yeast, S. cerevisiae ATCC 96581, and Candida shehatae NJ 23 was investigated using a 2(3)-full factorial design with 3 centrepoints. The results indicated that acetic acid inhibited the fermentation by C. shehatae NJ 23 markedly more than by bakers' yeast, whereas no significant difference in tolerance towards the compounds was detected between the S. cerevisiae strains. Furfural (2 g L-1) and the lignin derived compound p-hydroxybenzoic acid (2 g L-1) did not affect any of the yeasts at the cell mass concentration used. The results indicated that the linear model was not adequate to describe the experimental data (the p-values of curvatures were 0.048 for NJ 23 and 0.091 for bakers' yeast). Based on the results from the 2(3)-full factorial experiment, an extended experiment was designed based on a central composite design to investigate the influence of the factors on the specific growth rate (mu), biomass yield (Yx), volumetric ethanol productivity (QEtOH), and YEtOH. Bakers' yeast was chosen in the extended experiment due to its better tolerance towards acetic acid, which makes it a more interesting organism for use in industrial fermentations of lignocellulosic hydrolysates. The inoculum size was reduced in the extended experiment to reduce any increase in inhibitor tolerance that might be due to a large cell inoculum. By dividing the experiment in blocks containing fermentations performed with the same inoculum preparation on the same day, much of the anticipated systematic variation between the experiments was separated from the experimental error. The results of the fitted model can be summarised as follows: mu was decreased by furfural (0-3 g L-1). Furfural and acetic acid (0-10 g L-1) also interacted negatively on mu. Furfural concentrations up to 2 g L-1 stimulated Yx in the absence of acetic acid whereas higher concentrations decreased Yx. The two compounds interacted negatively on Yx and YEtOH. Acetic acid concentrations up to 9 g L-1 stimulated QEtOH, whereas furfural (0-3 g L-1) decreased QEtOH. Acetic acid in concentrations up to 10 g L-1 stimulated YEtOH in the absence of furfural, and furfural (0-2 g L-1) slightly increased YEtOH in the absence of acetic acid whereas higher concentrations caused inhibition. Acetic acid and furfural interacted negatively on YEtOH.

Cytochrome c release and mitochondria involvement in programmed cell death induced by acetic acid in Saccharomyces cerevisiae

Evidence is presented that mitochondria are implicated in the previously described programmed cell death (PCD) process induced by acetic acid in Saccharomyces cerevisiae. In yeast cells undergoing a PCD process induced by acetic acid, translocation of cytochrome c (CytC) to the cytosol and reactive oxygen species production, two events known to be proapoptotic in mammals, were observed. Associated with these events, reduction in oxygen consumption and in mitochondrial membrane potential was found. Enzymatic assays showed that the activity of complex bc(1) was normal, whereas that of cytochrome c oxidase (COX) was strongly decreased. This decrease is in accordance with the observed reduction in the amounts of COX II subunit and of cytochromes a+a(3). The acetic acid-induced PCD process was found to be independent of oxidative phosphorylation because it was not inhibited by oligomycin treatment. The inability of S. cerevisiae mutant strains (lacking mitochondrial DNA, heme lyase, or ATPase) to undergo acetic acid-induced PCD and in the ATPase mutant (knockout in ATP10) the absence of CytC release provides further evidence that the process is mediated by a mitochondria-dependent apoptotic pathway. The understanding of the involvement of a mitochondria-dependent apoptotic pathway in S. cerevisiae PCD process will be most useful in the further elucidation of an ancestral pathway common to PCD in metazoans.

Inhibition of Escherichia coli growth by acetic acid: a problem with methionine biosynthesis and homocysteine toxicity

The mechanism by which methionine relieves the growth inhibition of Escherichia coli K-12 that is caused by organic weak acid food preservatives was investigated. In the presence of 8 mM acetate the specific growth rate of E. coli Frag1 (in MacIlvaine's minimal medium pH 6.0) is reduced by 50%. Addition of methionine restores growth to 80% of that observed in untreated controls. Similar relief was seen with cultures treated with either benzoate or propionate. Mutants with an elevated intracellular methionine pool were almost completely resistant to the inhibitory effects of acetate, suggesting that the methionine pool becomes limiting for growth in acetate-treated cells. Measurement of the intracellular concentrations of pathway intermediates revealed that the homocysteine pool is increased dramatically in acetate-treated cells, suggesting that acetate inhibits a biosynthetic step downstream from this intermediate. Supplementation of the medium with homocysteine inhibits the growth of E. coli cells. Acetate inhibition of growth arises from the depletion of the intracellular methionine pool with the concomitant accumulation of the toxic intermediate homocysteine and this augments the effect of lowering cytoplasmic pH.

Acid sensing by the Drosophila olfactory system

The odour of acids has a distinct quality that is perceived as sharp, pungent and often irritating. How acidity is sensed and translated into an appropriate behavioural response is poorly understood. Here we describe a functionally segregated population of olfactory sensory neurons in the fruitfly, Drosophila melanogaster, that are highly selective for acidity. These olfactory sensory neurons express IR64a, a member of the recently identified ionotropic receptor (IR) family of putative olfactory receptors. In vivo calcium imaging showed that IR64a+ neurons projecting to the DC4 glomerulus in the antennal lobe are specifically activated by acids. Flies in which the function of IR64a+ neurons or the IR64a gene is disrupted had defects in acid-evoked physiological and behavioural responses, but their responses to non-acidic odorants remained unaffected. Furthermore, artificial stimulation of IR64a+ neurons elicited avoidance responses. Taken together, these results identify cellular and molecular substrates for acid detection in the Drosophila olfactory system and support a labelled-line mode of acidity coding at the periphery.

Effects of acetic acid and lactic acid on the growth of Saccharomyces cerevisiae in a minimal medium

Specific growth rates (mu) of two strains of Saccharomyces cerevisiae decreased exponentially (R2 > 0.9) as the concentrations of acetic acid or lactic acid were increased in minimal media at 30 degrees C. Moreover, the length of the lag phase of each growth curve (h) increased exponentially as increasing concentrations of acetic or lactic acid were added to the media. The minimum inhibitory concentration (MIC) of acetic acid for yeast growth was 0.6% w/v (100 mM) and that of lactic acid was 2.5% w/v (278 mM) for both strains of yeast. However, acetic acid at concentrations as low as 0.05-0.1% w/v and lactic acid at concentrations of 0.2-0.8% w/v begin to stress the yeasts as seen by reduced growth rates and decreased rates of glucose consumption and ethanol production as the concentration of acetic or lactic acid in the media was raised. In the presence of increasing acetic acid, all the glucose in the medium was eventually consumed even though the rates of consumption differed. However, this was not observed in the presence of increasing lactic acid where glucose consumption was extremely protracted even at a concentration of 0.6% w/v (66 mM). A response surface central composite design was used to evaluate the interaction between acetic and lactic acids on the specific growth rate of both yeast strains at 30 degrees C. The data were analysed using the General Linear Models (GLM) procedure. From the analysis, the interaction between acetic acid and lactic acid was statistically significant (P < or = 0.001), i.e., the inhibitory effect of the two acids present together in a medium is highly synergistic.

Involvement of vanilloid receptor VR1 and prostanoids in the acid-induced writhing responses of mice

We found that intraperitoneal injection of organic acids, such as propionic and lactic acid, are able to develop writhing responses in mice similarly as that of acetic acid. These acid-induced writhing reactions were significantly attenuated by capsazepine, a VR1 receptor-specific antagonist, but the phenylbenzoquinone-induced one was not, suggesting that the acids but not phenylbenzoquinone activate the VR1 receptor, which is involved in polymodal pain perception. Hoe 140, a bradykinin B2 receptor antagonist, also suppressed the acid-induced writhing response. Furthermore, these writhing responses were significantly suppressed after neonatal treatment with capsaicin, which treatment is known to destroy peripheral sensory afferent C-fibers. Capsazepine and Hoe 140 did not further attenuate the already reduced writhing responses of capsaicin-treated mice, suggesting that the acids stimulate the VR1 and the bradykinin B2 receptor in the pathway comprising sensory afferent C-fibers. On the other hand, indomethacin further significantly suppressed the writhing number of the capsaicin-treated animals, suggesting that the acid-induced pain perception requires prostanoid receptors not only in the pathway via capsaicin-sensitive C-fibers but also in other sensory pathways. These results provide the first evidence for the involvement of the vanilloid receptor in the acid-induced inflammatory pain perception via sensory C-fibers in addition to the known mediators bradykinin, neurokinins, and prostanoids.

Hog1 mitogen-activated protein kinase phosphorylation targets the yeast Fps1 aquaglyceroporin for endocytosis, thereby rendering cells resistant to acetic acid

Aquaporins and aquaglyceroporins form the membrane channels that mediate fluxes of water and small solute molecules into and out of cells. Eukaryotes often use mitogen-activated protein kinase (MAPK) cascades for the intracellular signaling of stress. This study reveals an aquaglyceroporin being destabilized by direct MAPK phosphorylation and also a stress resistance being acquired through this channel loss. Hog1 MAPK is transiently activated in yeast exposed to high, toxic levels of acetic acid. This Hog1 then phosphorylates the plasma membrane aquaglyceroporin, Fps1, a phosphorylation that results in Fps1 becoming ubiquitinated and endocytosed and then degraded in the vacuole. As Fps1 is the membrane channel that facilitates passive diffusional flux of undissociated acetic acid into the cell, this loss downregulates such influx in low-pH cultures, where acetic acid (pKa, 4.75) is substantially undissociated. Consistent with this downregulation of the acid entry generating resistance, sensitivity to acetic acid is seen with diverse mutational defects that abolish endocytic removal of Fps1 from the plasma membrane (loss of Hog1, loss of the soluble domains of Fps1, a T231A S537A double mutation of Fps1 that prevents its in vivo phosphorylation, or mutations generating a general loss of endocytosis of cell surface proteins [doa4Delta and end3Delta]). Remarkably, targetting of Fps1 for degradation may be the major requirement for an active Hog1 in acetic acid resistance, since Hog1 is largely dispensable for such resistance when the cells lack Fps1. Evidence is presented that in unstressed cells, Hog1 exists in physical association with the N-terminal cytosolic domain of Fps1.

Colposcopic appearance of anal squamous intraepithelial lesions: relationship to histopathology

PURPOSE

The incidence of anal cancer is increased in men with a history of anal receptive intercourse. Analogous to cervical cancer, whose precursor is cervical high-grade squamous intraepithelial lesion (HSIL), anal cancer may be preceded by anal HSIL. Although not yet proven, detection, follow-up, and treatment of HSIL may prevent development of anal cancer. Cervical colposcopic methodology was used to describe anal lesions and to determine if HSIL could be distinguished from low-grade squamous intraepithelial lesion (LSIL).

METHODS

The colposcopic characteristics of 385 biopsied anal lesions were described and correlated with results of histopathology in a cohort of 121 human immunodeficiency virus-positive and 31 human immunodeficiency-negative homosexual/bisexual men with anal lesions followed as part of a longitudinal study of anal squamous intraepithelial lesions. Color, contour, surface, and vascular patterns of anal lesions were analyzed and correlated with histologic diagnosis.

RESULTS

Sixty-seven percent of biopsies showed LSIL and 26 percent showed HSIL. The positive predictive value for anal HSIL in lesions with characteristics typical of cervical LSIL was 7.7 percent (95 percent confidence interval, 1.8-14), whereas the positive predictive value for anal HSIL in lesions with characteristics typical of cervical HSIL was 49 percent (95 percent confidence interval, 40-58).

CONCLUSIONS

The colposcopic appearance of different grades of anal squamous intraepithelial lesions was similar to those described for the cervix. Incorporation of colposcopy into assessment of anal disease could aid in distinguishing anal LSIL from HSIL.

Acetic acid increases stability of silage under aerobic conditions

The effects of various compounds on the aerobic stability of silages were evaluated. It has been observed that inoculation of whole-crop maize with homofermentative lactic acid bacteria leads to silages which have low stability against aerobic deterioration, while inoculation with heterofermentative lactic acid bacteria, such as Lactobacillus brevis or Lactobacillus buchneri, increases stability. Acetic acid has been proven to be the sole substance responsible for the increased aerobic stability, and this acid acts as an inhibitor of spoilage organisms. Therefore, stability increases exponentially with acetic acid concentration. Only butyric acid has a similar effect. Other compounds, like lactic acid, 1,2-propanediol, and 1-propanol, have been shown to have no effect, while fructose and mannitol reduce stability.

Probiotic bifidobacteria protect mice from lethal infection with Shiga toxin-producing Escherichia coli O157:H7

The anti-infectious activity of probiotic Bifidobacteria against Shiga toxin-producing Escherichia coli (STEC) O157:H7 was examined in a fatal mouse STEC infection model. Stable colonization of the murine intestines was achieved by the oral administration of Bifidobacterium breve strain Yakult (naturally resistant to streptomycin sulfate) as long as the mice were treated with streptomycin in their drinking water (5 mg/ml). The pathogenicity of STEC infection, characterized by marked body weight loss and subsequent death, observed in the infected controls was dramatically inhibited in the B. breve-colonized group. Moreover, Stx production by STEC cells in the intestine was almost completely inhibited in the B. breve-colonized group. A comparison of anti-STEC activity among several Bifidobacterium strains with natural resistance to streptomycin revealed that strains such as Bifidobacterium bifidum ATCC 15696 and Bifidobacterium catenulatum ATCC 27539(T) did not confer an anti-infectious activity, despite achieving high population levels similar to those of effective strains, such as B. breve strain Yakult and Bifidobacterium pseudocatenulatum DSM 20439. The effective strains produced a high concentration of acetic acid (56 mM) and lowered the pH of the intestine (to pH 6.75) compared to the infected control group (acetic acid concentration, 28 mM; pH, 7.15); these effects were thought to be related to the anti-infectious activity of these strains because the combination of a high concentration of acetic acid and a low pH was found to inhibit Stx production during STEC growth in vitro.

Anti-inflammatory and antinociceptive activity of diphenyl diselenide

OBJECTIVE AND DESIGN

Ebselen, an organoselenium compound is able to modulate the inflammatory response in rodents. In the present study, the anti-inflammatory and antinociceptive activity of diaryl diselenides and ebselen was studied.

MATERIALS

Adult male Wistar rats and albino mice were treated with diaryl diselenides and ebselen in different doses.

METHODS

Carrageenin-induced paw edema, tail-flick, formalin, acetic acid-induced abdominal writhing and capsaicin models of pain were carried out. Data were analyzed by ANOVA followed by Duncan's multiple range when appropriate.

RESULTS

In all models, the most promising profile was displayed by diphenyl diselenide, which produced anti-inflammatory and antinociceptive activity significantly higher than ebselen. Diphenyl diselenide also produced dose-dependent antinociception when assessed in acetic acid-induced abdominal constriction, tail-flick test or formalin and capsaicin-induced nociception.

CONCLUSION

The data presented here provide evidence that administration of diphenyl diselenide produced anti-inflammatory and antinociceptive activity.

Acetic acid upregulates the expression of genes for fatty acid oxidation enzymes in liver to suppress body fat accumulation

We investigated the effect of acetic acid (AcOH) on the prevention of obesity in high-fat-fed mice. The mice were intragastrically administrated with water or 0.3 or 1.5% AcOH for 6 weeks. AcOH administration inhibited the accumulation of body fat and hepatic lipids without changing food consumption or skeletal muscle weight. Significant increases were observed in the expressions of genes for peroxisome-proliferator-activated receptor alpha (PPARalpha) and for fatty-acid-oxidation- and thermogenesis-related proteins: acetyl-CoA oxidase (ACO), carnitine palmitoyl transferase-1 (CPT-1), and uncoupling protein-2 (UCP-2), in the liver of the AcOH-treatment groups. PPARalpha, ACO, CPT-1, and UCP-2 gene expressions were increased in vitro by acetate addition to HepG2 cells. However, the effects were not observed in cells depleted of alpha2 5'-AMP-activated protein kinase (AMPK) by siRNA. In conclusion, AcOH suppresses accumulation of body fat and liver lipids by upregulation of genes for PPARalpha and fatty-acid-oxidation-related proteins by alpha2 AMPK mediation in the liver.

Do fishes have nociceptors? Evidence for the evolution of a vertebrate sensory system

Nociception is the detection of a noxious tissue-damaging stimulus and is sometimes accompanied by a reflex response such as withdrawal. Pain perception, as distinct from nociception, has been demonstrated in birds and mammals but has not been systematically studied in lower vertebrates. We assessed whether a fish possessed cutaneous nociceptors capable of detecting noxious stimuli and whether its behaviour was sufficiently adversely affected by the administration of a noxious stimulus. Electrophysiological recordings from trigeminal nerves identified polymodal nociceptors on the head of the trout with physiological properties similar to those described in higher vertebrates. These receptors responded to mechanical pressure, temperatures in the noxious range (more than 40 degrees C) and 1% acetic acid, a noxious substance. In higher vertebrates nociceptive nerves are either A-delta or C fibres with C fibres being the predominating fibre type. However, in the rainbow trout A-delta fibres were most common, and this offers insights into the evolution of nociceptive systems. Administration of noxious substances to the lips of the trout affected both the physiology and the behaviour of the animal and resulted in a significant increase in opercular beat rate and the time taken to resume feeding, as well as anomalous behaviours. This study provides significant evidence of nociception in teleost fishes and furthermore demonstrates that behaviour and physiology are affected over a prolonged period of time, suggesting discomfort.

Thalamic control of visceral nociception mediated by T-type Ca2+ channels

Sensations from viscera, like fullness, easily become painful if the stimulus persists. Mice lacking alpha1G T-type Ca2+ channels show hyperalgesia to visceral pain. Thalamic infusion of a T-type blocker induced similar hyperalgesia in wild-type mice. In response to visceral pain, the ventroposterolateral thalamic neurons evokeda surge of single spikes, which then slowly decayed as T type-dependent burst spikes gradually increased. In alpha1G-deficient neurons, the single-spike response persisted without burst spikes. These results indicate that T-type Ca2+ channels underlie an antinociceptive mechanism operating in the thalamus andsupport the idea that burst firing plays a critical role in sensory gating in the thalamus.

When transcriptome meets metabolome: fast cellular responses of yeast to sudden relief of glucose limitation

Within the first 5 min after a sudden relief from glucose limitation, Saccharomyces cerevisiae exhibited fast changes of intracellular metabolite levels and a major transcriptional reprogramming. Integration of transcriptome and metabolome data revealed tight relationships between the changes at these two levels. Transcriptome as well as metabolite changes reflected a major investment in two processes: adaptation from fully respiratory to respiro-fermentative metabolism and preparation for growth acceleration. At the metabolite level, a severe drop of the AXP pools directly after glucose addition was not accompanied by any of the other three NXP. To counterbalance this loss, purine biosynthesis and salvage pathways were transcriptionally upregulated in a concerted manner, reflecting a sudden increase of the purine demand. The short-term dynamics of the transcriptome revealed a remarkably fast decrease in the average half-life of downregulated genes. This acceleration of mRNA decay can be interpreted both as an additional nucleotide salvage pathway and an additional level of glucose-induced regulation of gene expression.

Dietary acetic acid reduces serum cholesterol and triacylglycerols in rats fed a cholesterol-rich diet

To investigate the efficacy of the intake of vinegar for prevention of hyperlipidaemia, we examined the effect of dietary acetic acid, the main component of vinegar, on serum lipid values in rats fed a diet containing 1% (w/w) cholesterol. Animals were allowed free access to a diet containing no cholesterol, a diet containing 1% cholesterol without acetic acid, or a diet containing 1% cholesterol with 0·3% (w/w) acetic acid for 19 d. Then, they were killed after food deprivation for 7 h. Cholesterol feeding increased serum total cholesterol and triacylglycerol levels. Compared with the cholesterol-fed group, the cholesterol and acetic acid-fed group had significantly lower values for serum total cholesterol and triacylglycerols, liver ATP citrate lyase (ATP-CL) activity, and liver 3-hydroxy-3-methylglutaryl-CoA content as well as liver mRNA levels of sterol regulatory element binding protein-1, ATP-CL and fatty acid synthase (P<,0·05). Further, the serum secretin level, liver acyl-CoA oxidase expression, and faecal bile acid content were significantly higher in the cholesterol and acetic acid-fed group than in the cholesterol-fed group (P<0·05). However, acetic acid feeding affected neither the mRNA level nor activity of cholesterol 7a-hydroxylase. In conclusion, dietary acetic acid reduced serum total cholesterol and triacylglycerol: first due to the inhibition of lipogenesis in liver; second due to the increment in faecal bile acid excretion in rats fed a diet containing cholesterol.

Modelling the growth kinetics of Listeria as a function of temperature, pH and organic acid concentration

The combined effects of temperature, pH and organic acids (lactic, acetic and propionic) on the growth kinetics of Listeria innocua ATCC 33090 were studied. First, a multiplicative model was built assuming independent effects of all environmental factors. Thus, the model was expanded by the inclusion of a novel term describing the effects of interactions on the growth/no growth limits. The proposed approach allows an accurate description of the boundary between growth and no growth of Listeria.

Crataegus pinnatifida polysaccharide alleviates colitis via modulation of gut microbiota and SCFAs metabolism

Inflammatory bowel disease (IBD) afflicted individual and most medications have side-effects. Crataegus pinnatifida (Hawthorn), which is a safe medicine and food homolog plant, has been reported to prevent colitis in murine. Yet the bioactivity component and the underlying molecular mechanism remain unclear. Here, we established a direct link between colitis induced by dextran sulphate sodium (DSS) in mice and polysaccharide HAW1-2 isolated from hawthorn. Our results showed HAW1-2 restored the pathological lesions in colon and inhibited the expression of inflammatory cytokines including IL-1β, IL-6 and TNF-α. Meanwhile, IKKα/β, IκBα, NF-κB and the phosphorylation levels were inhibited significantly. These findings suggested HAW1-2 could alleviate the inflammation of colon. Further, we found the composition of gut microbiota was modified and Bacteroides including Alistipes and Odoribacter were significantly enriched. Besides, we showed Alistipes and Odoribacter were positively co-related with acetic acid and propionic acid while were negatively co-related with inflammatory cytokines. Finally, we demonstrated the anti-inflammation activity of HAW1-2 might be induced by acetic acid. Together, the present data revealed HAW1-2 could directly modify the gut microbiota, especially for Bacteroides, and generate SCFAs to inhibit colitis. It also implies microbiota-directed intervention in IBD patients should be particularly given more attention.