Gabapentin alleviated the cough hypersensitivity and neurogenic inflammation in a guinea pig model with repeated intra-esophageal acid perfusion

OBJECTIVE

The anti-tussive effect of gabapentin and its underlying neuromodulatory mechanism were investigated via a modified guinea pig model of gastroesophageal reflux-related cough (GERC).

METHODS

Intra-esophageal perfusion with hydrochloric acid (HCl) was performed every other day 12 times to establish the GERC model. High-dose gabapentin (48 mg/kg), low-dose gabapentin (8 mg/kg), or saline was orally administered for 2 weeks after modeling. Cough sensitivity, airway inflammation, lung and esophagus histology, levels of substance P (SP), and neurokinin-1 (NK1)-receptors were monitored.

RESULTS

Repeated intra-esophageal acid perfusion aggravated the cough sensitivity in guinea pigs in a time-dependent manner. The number of cough events was significantly increased after 12 times HCl perfusion, and the hypersensitivity period was maintained for 2 weeks. The SP levels in BALF, trachea, lung, distal esophagus, and vagal ganglia were increased in guinea pigs receiving HCl perfusion. The intensity of cough hypersensitivity in the GERC model was significantly correlated with increased SP expression in the airways. Both high and low doses of gabapentin administration could reduce cough hypersensitivity exposed to HCl perfusion, attenuate airway inflammatory damage, and inhibit neurogenic inflammation by reducing SP expression from the airway and vagal ganglia.

CONCLUSIONS

Gabapentin can desensitize the cough sensitivity in the GERC model of guinea pig. The anti-tussive effect is associated with the alleviated peripheral neurogenic inflammation as reflected in the decreased level of SP.

Growth hormone-releasing hormone antagonists protect against hydrochloric acid-induced endothelial injury in vitro

Growth hormone-releasing hormone (GHRH) regulates the synthesis of growth hormone from the anterior pituitary gland, and it is involved in inflammatory responses. On the other hand, GHRH antagonists (GHRHAnt) exhibit the opposite effects, resulting in endothelial barrier enhancement. Exposure to hydrochloric acid (HCL) is associated with acute and chronic lung injury. In this study, we investigate the effects of GHRHAnt in HCL-induced endothelial barrier dysfunction, utilizing commercially available bovine pulmonary artery endothelial cells (BPAEC). Cell viability was measured by utilizing 3-(4,5-dimethylthiazol2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, fluorescein isothiocyanate (FITC)-dextran was used to assess barrier function. Our observations suggest that GHRHAnt exert protective effects against HCL-induced endothelial breakdown, since those peptides counteract HCL-triggered paracellular hyperpermeability. Based on those findings, we propose that GHRHAnt represent a new therapeutic approach towards HCL-induced endothelial injury.

Vibrio parahaemolyticus CadC regulates acid tolerance response to enhance bacterial motility and cytotoxicity

Pathogens adapted to sub-lethal acidic conditions could increase the virulence and survival ability under lethal conditions. In the aquaculture industry, feed acidifiers have been used to increase the growth of aquatic animals. However, there is limited study on the effects of acidic condition on the virulence and survival of pathogens in aquaculture. In this study, we investigated the survival ability of Vibrio parahaemolyticus at lethal acidic pH (4.0) after adapted the bacteria to sub-lethal acidic pH (5.5) for 1 hr. Our results indicated that the adapted strain increased the survival ability at lethal acidic pH invoked by an inorganic (HCl) or organic (citric) acid. RNA-sequencing (RNA-seq) results revealed that 321 genes were differentially expressed at the sub-lethal acidic pH including cadC, cadBA and groES/groEL relating to acid tolerance response (ATR), as well as genes relating to outer membrane, heat-shock proteins, phosphotransferase system and flagella system. Quantitative real-time polymerase chain reaction (qRT-PCR) confirmed that cadC and cadBA were upregulated under sub-lethal acidic conditions. The CadC protein could directly regulate the expression of cadBA to modulate the ATR in V. parahaemolyticus. RNA-seq data also indicated that 113 genes in the CadC-dependent way and 208 genes in the CadC-independent way were differentially expressed, which were related to the regulation of ATR. Finally, the motility and cytotoxicity of the sub-lethal acidic adapted wild type (WT) were significantly increased compared with the unadapted strain. Our results demonstrated that the dietary acidifiers may increase the virulence and survival of V. parahaemolyticus in aquaculture.

The Effects of Artificially Dosed Adult Rumen Contents on Abomasum Transcriptome and Associated Microbial Community Structure in Calves

This study aimed to investigate the changes in abomasum transcriptome and the associated microbial community structure in young calves with artificially dosed, adult rumen contents. Eight young bull calves were randomly dosed with freshly extracted rumen contents from an adult cow (high efficiency (HE), n = 4), or sterilized rumen content (Con, n = 4). The dosing was administered within 3 days of birth, then at 2, 4, and 6 weeks following the initial dosing. Abomasum tissues were collected immediately after sacrifice at 8 weeks of age. Five genera (Tannerella, Desulfovibrio, Deinococcus, Leptotrichia, and Eubacterium; p < 0.05) showed significant difference in abundance between the treatments. A total of 975 differentially expressed genes were identified (p < 0.05, fold-change > 1.5, mean read-counts > 5). Pathway analysis indicated that up-regulated genes were involved in immune system process and defense response to virus, while the down-regulated genes involved in ion transport, ATP biosynthetic process, and mitochondrial electron transport. Positive correlation (r > 0.7, p < 0.05) was observed between TRPM4 gene and Desulfovibrio, which was significantly higher in the HE group. TRPM4 had a reported role in the immune system process. In conclusion, the dosing of adult rumen contents to calves can alter not only the composition of active microorganisms in the abomasum but also the molecular mechanisms in the abomasum tissue, including reduced protease secretion and decreased hydrochloric acid secretion.

Surviving host - and food relevant stresses: phenotype of L. monocytogenes strains isolated from food and clinical sources

The aim of this study was to compare the phenotype of 40 strains of L. monocytogenes under food and host relevant stress conditions. The strains were chosen to represent food and clinical isolates and to be equally distributed between the most relevant clonal complexes for clinical and food isolates (CC1 and CC6 vs CC121 and CC9), plus one group of eight strains of rare clonal complexes. Human-associated CC1 had a faster maximal growth rate than the other major complexes, and the lag time of CC1 and CC6 was significantly less affected by the addition of 4% NaCl to the medium. Food-associated CC9 strains were hypohemolytic compared to other clonal complexes, and all strains found to be resistant to increased concentrations of benzalkonium chloride belonged to CC121 and were positive for Tn6188 carrying the qacH gene. Lactic acid affected the survival of L. monocytogenes more than HCl, and there was a distinct, strain specific pattern of acid tolerant and sensitive strains. Strains from CC6 and human clinical isolates are less resilient under acid stress than those from other complexes and from food. One strain isolated from a human patient exhibited significant growth defects across all conditions.

Validation of the TrichinEasy® digestion system for the detection of Anisakidae larvae in fish products

Anisakis and other parasites belonging to the Anisakidae family are organisms of interest for human health, because of their high zoonotic potential. Parasites belonging to this family can cause Anisakiasis, a parasitological disease caused by the ingestion of raw, infested fish products. Furthermore, evidence from the EFSA (European Food Safety Authority; EFSA 2010) has highlighted the allergological potential of nematodes belonging to the Anisakis genre. The detection and identification of Anisakidae larvae in fish products requires an initial visual inspection of the fish sample, as well as other techniques such as candling, UV illumination and artificial digestion. The digestion method consists of the simulation of digestive mechanics, which is made possible by the utilization of HCl and pepsin, according to EC Regulation 2075/2005. In this study, a new Anisakidae larvae detection method using a mechanical digestion system called Trichineasy® was developed. A total of 142 fish samples, belonging to 14 different species, were examined to validate the method. A reaction mixture with 100 g of sample, 10 g of pepsin (1:10000 NF) and 50 ml of 10% HCl at 36 ± 1°C for 20 minutes was evaluated to be the best condition for the digestion of fish samples. These parameters have also allowed the detection of viable larvae after digestion. The results confirm this instrumentation as a valuable and safe tool for the detection of Anisakidae larvae in fishery products.

[Changes in gastric function in rats after intragastric introduction of corvitin at high doses]

Intragastric administration of corvitin at doses of 10, 20 and 40 mg/kg dose-dependently increased the volume of gastric juice and the total production of hydrochloric acid (HA). Amplification of hexosamines and cysteine production was observed only when the study drug was administered at a dose of 10 mg/kg. When corvitin was used at 20 and 40 mg/kg, these parameters were at the level of control values. Protein production increased in response to 10 and 20 mg/kg corvitin, but fell below the control values after administration of 40 mg/kg of the drug. The level of blood flow in the gastric mucosa increased following administration of 10 mg/kg corvitin, was not different from the baseline after 20 mg/kg of the drug and significantly decreased in response to 40 mg/kg of flavonoid. Our results indicate that a single intragastric application of corvitin at dose of 10 mg/kg activates gastric defense mechanisms. At 20 and 40 mg/kg, corvitin does not affect them but gradually reduces blood flow in gastric mucosa, causes a disturbance of protein synthesis and hypersecretion of HA into the cavity of the stomach, which can lead to disruption of the digestive process and the integrity of gastric mucosa.

Ethanol-based organosolv treatment with trace hydrochloric acid improves the enzymatic digestibility of Japanese cypress (Chamaecyparis obtusa) by exposing nanofibers on the surface

The effects of adding trace acids in ethanol based organosolv treatment were investigated to increase the enzymatic digestibility of Japanese cypress. A high glucose yield (60%) in the enzymatic hydrolysis was obtained by treating the sample at 170 °C for 45 min in 50% ethanol liquor containing 0.4% hydrochloric acid. Moreover, the enzymatic digestibility of the treated sample was improved to ∼70% by changing the enzyme from acremonium cellulase to Accellerase1500. Field emission scanning electron microscopy revealed the presence of lignin droplets and partial cellulose nanofibers on the surface of the treated sample. Simultaneous saccharification and fermentation of the treated samples using thermotolerant yeast (Kluyveromyces marxianus NBRC1777) was tested. A high ethanol concentration (22.1 g/L) was achieved using the EtOH50/W50/HCl0.4-treated sample compared with samples from other treatments.

Simulated gastrointestinal digestion of Pru ar 3 apricot allergen: assessment of allergen resistance and characterization of the peptides by ultra-performance liquid chromatography/electrospray ionisation mass spectrometry

RATIONALE

Non-specific lipid transfer proteins (ns-LTPs) are major food allergens of the Rosaceae family. The severity of allergic reactions often relates to resistance of the allergen to digestion. Thus, it is important to evaluate the digestibility of these proteins and characterise the peptides generated in the gastrointestinal tract.

METHODS

Simulated gastrointestinal digestion of purified allergen Pru ar 3 was performed using pepsin for the gastric phase in aqueous HCl at pH = 2 and chymotrypsin and trypsin for the intestinal phase in aqueous NH(4)HCO(3) at pH = 7.8. The peptide mixture obtained was analysed by ultra-performance liquid chromatography/electrospray ionisation mass spectrometry (UPLC/ESI-MS). Peptide sequences were identified by comparing their molecular mass to that obtained by in silico digestion, and were confirmed by the ions obtained by in-source fragmentation. Semi-quantification was performed for the intact protein by comparison with internal standards.

RESULTS

The resistance to gastrointestinal digestion of Pru ar 3 allergen was evaluated to be 9%. This value is consistent with that found for grape LTP, but much lower than the resistance found for peach LTP (35%). All the peptides generated were identified by ESI-MS on the basis of their molecular mass and from the ions generated from in-source fragmentation. Apart from low molecular mass peptides, five high molecular mass peptides (4500-7000 Da) containing disulphide bridges were identified. ESI-MS of the intact protein indicated a less compact folded structure when compared to that of the homologous peach LTP.

CONCLUSIONS

An extensive characterisation of the peptides generated from the gastrointestinal digestion of Pru ar 3 allergen was performed here for the first time via UPLC/ESI-MS analysis. The digestibility of the allergen was evaluated and compared with that of other LTPs, demonstrating that only a small amount of undigested protein remains, and that specific proteolytic action involves immunodominant epitopes. These data might explain the lower allergenicity of apricot LTP compared to peach LTP, despite their high sequence homology.

[Study on germination characteristic of seed of Dendranthema indicum]

OBJECTIVE

To find out the optimum condition for the germination of seed of Dendranthema indicum by studying the effects of pretreatment,phytohormone and temperature on it, and offer the basis for its standardized culture.

METHODS

The seed purity, weight per 1000 seeds, seed moisture content and seed viability were determined. The germination of D. indicum seed was tested under following conditions: pretreatment (acid, base, warm water, boiling water), phytohormone (IBA, 6-BA, NAA) and treatments under different temperature (10, 20, 25, 30 degrees C).

RESULTS

The seed purity was 99.4%; The weight per 1000 seeds was 0.2941 g; The seed moisture content was 4.39%; The seed viability was 85.3%; The tests of pretreatment couldnt increase the germination of D. indicum seed; Phytohormone had limited effect on the germination of the seed; Temperature condition showed significant effects on the germination.

CONCLUSION

The optimum condition for the germination of the seed of D. indicum is 25 degrees C on filter paper.

[Clinical and functional disorders of the stomach-in patients with psoriasis in the presence of chronic opisthorchiasis]

OBJECTIVE

to study the clinical and functional status of the stompach in patients with psoriasis in the presence of chronic opisthorchiasis (CO). Subjects and methods. Ninety patients with psoriasis concurrent with CO (a study group (Group 1)), 70 with psoriasis (a comparison group (Group 2)), 70 with CO (Group 3), and 30 healthy individuals were examined. All the patients underwent fractional gastric secretory studies and esophagogastroduodenoscopy (EGDS).

RESULTS

The study group showed a reduction in stimulated hydrochloric acid output (4.25+/-0.38 mmol/hour), which was significantly less than that in Groups 2 and 3 and healthy individuals [5.87+/-0.51 (p<0.001); 6.86+/-0.59 (p<0.05), and 10.73+/-0.84 mmnol/hour (p<0.001), respectively]. In the study group, stimulated pepsin output (4.87+/-0.49 mmol/hour) was also significantly less than that in the other groups. Reduced basal hydrochloric acid output was found in 65.5% of the study group patients, whose number was significantly larger than that in the comparison group [44.3% (p<0.05)] and its stimulated output was less in 80 and 62.9% in the study and comparison groups, respectively (p < 0.05). A reduction in pepsin output in the basal secretion phase was revealed in 57.8 and 37.1% of the patients in the study and comparison groups, respectively (p<0.05) while that in the stimulated phase was in 63.3 and 34.3% (p<0.001). Thus, gastric secretory function in psoriatic patients is characterized by reduced hydrochloric acid and pepsin outputs and it is more impaired in patients with mixed pathology, which necessitates anthelmintic therapy in this category of patients.

The effect of acid pretreatment on the anaerobic digestion and dewatering of waste activated sludge

Waste activated sludge (WAS) is difficult to degrade in anaerobic digestion systems and pretreatments have been shown to speed up the hydrolysis stage. Here the effects of acid pretreatment (pH 6-1) using HCl on subsequent digestion and dewatering of WAS have been investigated. Optimisation of acid dosing was performed considering digestibility benefits and level of acid required. Pretreatment to pH 2 was concluded to be the most effective. In batch digestion this yielded the same biogas after 13 days as compared to untreated WAS at 21 days digestion. In semi-continuous digestion experiments (12 day hydraulic retention time at 35°C) it resulted in a 14.3% increase in methane yield compared to untreated WAS, also Salmonella was eradicated in the digestate. Dewatering investigations suggested that the acid pretreated WAS required 40% less cationic polymer addition to achieve the same cake solid content. A cost analysis was also carried out.

A solid-state 17O NMR study of L -phenylalanine and L -valine hydrochlorides

We have presented an experimental investigation of the oxygen-17 chemical shielding (CS) and electric-field-gradient (EFG) tensors for alpha-COOH groups in polycrystalline amino acid hydrochlorides. The 17O CS and EFG tensors including the relative orientations between the two NMR tensors are determined in [17O]-L-phenylalanine hydrochloride and [17O]-L-valine hydrochloride by the analysis of the 17O magic-angle-spinning (MAS) and stationary NMR spectra obtained at 9.4, 11.7, 16.4, and 21.8 T. The quadrupole coupling constants (CQ) and the span of the CS tensors are found to be 8.41-8.55 MHz and 7.35-7.41MHz, and 548-570 ppm and 225-231 ppm, for carbonyl and hydroxyl oxygen atoms, respectively. Extensive quantum chemical calculations using density functional theory (DFT) have been also carried out for a hydrogen-bonding model. It is demonstrated that the behavior of the dependence of hydrogen-bond distances on 17O NMR tensors for the halogen ions is different from those for the water molecule.

Deuterium quadrupolar tensors of L-histidine hydrochloride monohydrate-d7

A deuterium NMR study at 14 T of a single crystal of L-histidine hydrochloride monohydrate has determined the deuteron quadrupole coupling constants CQ, asymmetry parameters eta, and electric field gradient orientation for the imidazolium and primary ammonium groups and for a water of crystallization. The imidazolium deuterons, which have very long relaxation times, have quite different coupling constants, reflecting different hydrogen bonding but nearly identical orientations, with the most distinct principal axis in both cases nearly parallel to the N-D vector. The -ND3 groups undergo 3-fold hops about the C-N bond axis and have typical quadrupole couplings; the D2O undergoes 2-fold hops, leading to a tensor with a large asymmetry parameter. With appropriate corrections for vibrational averaging, density functional cluster calculations give an excellent fit to the imidazolium tensor magnitudes and orientations.

In vitro effects of hydrochloric acid and various concentrations of acetic, propionic, butyric, or valeric acids on bioelectric properties of equine gastric squamous mucosa

OBJECTIVE

To compare the effects of hydrochloric acid (HCl) and various concentrations of volatile fatty acids (VFAs) on tissue bioelectric properties of equine stomach nonglandular (NG) mucosa.

SAMPLE POPULATION

Gastric tissues obtained from 48 adult horses.

PROCEDURES

NG gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference (PD) were measured and electrical resistance (R) and conductance calculated for tissues after addition of HCl and VFAs (5, 10, 20, and 40 mM) in normal Ringer's solution (NRS).

RESULTS

Mucosa exposed to HCl in NRS (pH of 1.5 and, to a lesser extent, 4.0) had a significant decrease in Isc, PD, and R, whereas tissues exposed to acetic acid at a pH of < 4.0, propionic and butyric acids at a pH of <or= 4.0, and valeric acid at a pH of <or= 7.0 induced a concentration-dependent effect on reduction in these same values. Values for Isc returned to baseline (recovery of sodium transport) after addition of calcium carbonate in tissues exposed to all concentrations of VFAs except the higher concentrations of valeric acid at a pH of <or= 4.0. Histologic examination revealed cell swelling in the mucosal layers below and adjacent to the stratum corneum in tissues exposed to HCl and VFAs at a pH of <or= 4.0.

CONCLUSIONS AND CLINICAL RELEVANCE

The VFAs, especially acetic acid, in the presence of HCl at a pH of <or= 4.0 appear to be important in the pathogenesis of NG mucosal ulcers in horses.

Global Structure Analysis of Acid-Unfolded Myoglobin with Consideration to Effects of Intermolecular Coulomb Repulsion on Solution X-ray Scattering†

To obtain information on the global structure of protein in the acid-unfolded (AU) state, the structure of apomyoglobin (apoMb) was analyzed by using the solution X-ray scattering (SXS) method. SXS profiles were obtained over a wide range of protein concentrations, 1-18 mg mL-1, under strongly acidic conditions. From analysis of the SXS profile extrapolated to a zero protein concentration, the mean square radius, Rsq, of AU-apoMb at 20 mM HCl was estimated to be 4.81 +/- 0.31 nm. This estimate is more than 1.3 nm larger than those of 3.0-3.5 nm reported thus far. The difference originates from the fact that effects of Coulomb repulsive forces acting between AU-apoMb molecules have not been correctly taken into account in the conventional analysis. In fact, even at a low protein concentration of 1 mg mL-1 close to the limit of measurement in the present SXS method, the solution condition applicable to estimating accurately structural parameters of AU-apoMb is very limited. At HCl concentrations lower than 10 mM, the scattering intensity at a small scattering vector decreases remarkably through the effect of intermolecular repulsive forces and the forward scattering intensity is significantly lower than the estimate from the partial specific volume of protein. On the other hand, at HCl concentrations higher than 50 mM, some compact molten-globule-like structures emerge. As a result, the intermediate concentration of 20 mM HCl is the best choice of the solution condition for determining Rsq of AU-apoMb. The effect of intermolecular Coulomb repulsion on the SXS profile of AU-apoMb is at its maximum for forward scattering and decreases monotonously with an increase in the scattering angle to be virtually negligible at K approximately 0.63 nm(-1). Whereas urea-denatured apoMb shows a SXS profile typical of Gaussian chains, the intrinsic SXS profile of AU-apoMb differs significantly from those of Gaussian chains.

A comparative study of proteolysis methods for the measurement of 3-nitrotyrosine residues: enzymatic digestion versus hydrochloric acid-mediated hydrolysis

A common approach for the quantification of 3-nitrotyrosine (NY) in routine analyses relies on the cleavage of peptide bonds in order to release the free amino acids from proteins in tissues or fluids. NY is usually monitored by either GC-MS(/MS) or LC-MS/MS techniques. Various proteolysis methods have been employed to combine digestion efficiency with prevention of artifactual nitration of tyrosine. However, so far, no study was designed to compare the HCl-based hydrolysis method with enzymatic digestion in terms of reliability for the measurement of NY. The present work addresses the digestion efficiency of BSA using either 6M HCl, pronase E or a cocktail of enzymes (pepsin, pronase E, aminopeptidase, prolidase) developed in our laboratory. The HCl-based hydrolysis leads to a digestion yield of 95%, while 25 and 75% are achieved with pronase E and the cocktail of enzymes, respectively. These methods were compared in terms of NY measurement and the results indicate that a prior reduction of the disulfide bonds ensures a reliable quantification of NY. We additionally show that the enzyme efficacy is not altered when the digestion is carried out in the presence of BSA with a high content of NY.

Comparative study on chemical pretreatments to accelerate enzymatic hydrolysis of aquatic macrophyte biomass used in water purification processes

In this study, enzymatic hydrolysis of two floating aquatic plants which are suitable for water purification, water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.), was performed to produce sugars. Twenty chemical pretreatments were comparatively examined in order to improve the efficiency of enzymatic hydrolysis. As a result, the alkaline/oxidative (A/O) pretreatment, in which sodium hydroxide and hydrogen peroxide were used, was the most effective pretreatment in terms of improving enzymatic hydrolysis of the leaves of water hyacinth and water lettuce. The amount of reducing sugars in enzymatic hydrolysate of water lettuce leaves was 1.8 times higher than that of water hyacinth leaves, therefore water lettuce seems to be more attractive as a biomass resource than water hyacinth. Although roots of these plants contained large amounts of polysaccharides such as cellulose and hemicellulose, they generated less monosaccharides than from leaves, no matter which chemical pretreatment was tested.

Unique uptake of acid-prepared mesoporous spheres by lung epithelial and mesothelioma cells

Lung cancers, malignant mesotheliomas (MM), and fibrosis are devastating diseases with limited treatment strategies, in part due to poorly-effective drug delivery to affected areas of lung. We hypothesized that acid-prepared mesoporous spheres (APMS) (1-2 microm diameter, 40 A pore size) might be effective vehicles for pulmonary chemotherapeutic drug delivery. To assess this, APMS, chemically modified with different surface molecules (lipid, a linker having a terminal amine group, a thiol group, or tetraethylene glycol [TEG]), were evaluated for uptake and possible cytotoxic effects after in vitro administration to murine alveolar epithelial Type II (C10) and human mesothelioma (MM) cells and after intrapleural or intranasal administration to C57Bl/6 mice. APMS coated with TEG (APMS-TEG) were most efficiently taken up by C10 and MM cells. The mechanism of cell uptake was rapid, actin-dependent, and did not involve clathrin- or caveolae-mediated mechanisms nor fusion of membrane-bound APMS with lysosomes. When injected intrapleurally in mice, APMS-TEG were taken up by both CD45-positive and -negative cells of the diaphragm, lung, and spleen, whereas APMS administered by the intranasal route were predominantly in lung epithelial cells and alveolar macrophages. After intrapleural or intranasal administration, APMS were nonimmunogenic and nontoxic as evaluated by differential cell counts and lactate dehydrogenase levels in bronchoalveolar and pleural lavage fluids. In the treatment of lung and pleural diseases, APMS-TEG may be useful tools to deliver chemotherapeutic drugs or molecular constructs.

The use of a D-optimal design to model the effects of temperature, NaCl, type and acid concentration on Lactobacillus pentosus IGLAC01

AIMS

To study the effects of temperature, NaCl and acid (HCl, citric, acetic and lactic) concentrations on the specific growth rate (mu), lag phase (lambda), and h0 of Lactobacillus pentosus IGLAC01.

METHODS AND RESULTS

Response surface (RS) methodology (D-optimal design) was used with a dummy variable, to account for the different types of acids. The variable ranges were: 16-30 degrees C, 0-70 g l-1 NaCl, and 0-5 g l-1 acid (or 0-2.5 g l-1 HCl). Time to detection from optical density data was used to deduce mu and lambda. The RS models for log2mu and log2lambda, according to acid types, were estimated and the effects of variables were quantified by their z-generalized values. A relationship between ln h0 with temperature was also found.

CONCLUSIONS

The mu of L. pentosus IGLAC01 can be doubled by increasing temperature by 10.3 degrees C or by decreasing NaCl by 48 g l-1 (harmonic, averaged, z values, Z); citric was the least inhibitory acid (zmu=-96.2) and lactic the strongest (zmu=-5.7), according to their generalized z values, z. A twofold lambda increase was achieved from a decrease of 3.1 degrees C (HCl), or 4.27 degrees C (citric) or 36 g l-1 NaCl increase (both acids) (expressed as zlambda ); the same effect was obtained from a decrease of 4.37 degrees C, 54 g l-1 NaCl increase, or 10 g l-1 acetic or lactic acid additions (expressed as Zlambda values).

SIGNIFICANCE AND IMPACT OF THE STUDY

Valuable information on the effects of environmental variables on the biological parameters of L. pentosus IGLAC01, which could be used for the optimization of olive, cucumber or other vegetable fermentations, is obtained.

c-Src control of chloride channel support for osteoclast HCl transport and bone resorption

Bone degradation by osteoclasts depends upon active transport of hydrogen ions to solubilize bone mineral. This transport is supported by the parallel actions of a proton ATPase and a chloride channel located in the osteoclast ruffled membrane. We have previously identified a novel chloride channel, p62, which appears to be the avian counterpart to CLIC-5b and is expressed coincident with the appearance of acid secretion as avian osteoclasts differentiate in culture. In this article, we show that suppression of CLIC-5b in differentiating avian osteoclasts results in decreased acidification by vesicles derived from these cells and decreased ability of the cells to resorb bone. Acidification is rescued by the presence of valinomycin, consistent with a selective loss of chloride channel but not proton pump activity. Osteoclast bone resorption is known to be dependent on the expression of the tyrosine kinase, c-Src. We show that CLIC-5b from osteoclasts has affinity for both Src SH2 and SH3 domains. We find that suppression of expression of Src in developing osteoclasts results in decreased vesicular acidification, which is rescued by valinomycin, consistent with the loss of chloride conductance in the proton pump-containing vesicles. Suppression of c-Src causes no change in the steady state level of CLIC-5b expression, but does result in failure of proton pump and CLIC-5b to colocalize in cultured osteoclast precursors. We conclude that suppression of c-Src interferes with osteoclast bone resorption by disrupting functional co-localization of proton pump and CLIC-5b.

Distribution of Orally Ingested Hydrochloric Acid in the Thoracoabdominal Cavity After Death

The authors encountered a case of hydrochloric acid (HCl) poisoning, thought to be caused by oral ingestion of concentrated HCl. Coagulation of the surface of the tongue and the mucosa of the pharynx, esophagus, and stomach were observed at forensic autopsy. An overabundance of Cl- was found in the gastric contents, corresponding to 8.19 mL of concentrated HCl. This was suggested to be a lethal oral dose of concentrated HCl, and the cause of death was determined to be HCl poisoning. Measuring the pH and concentrations of various ions in body fluids and contents of the alimentary tract enabled postmortem diffusion of HCl to be determined.

Dyspeptic symptoms associated with hypersensitivity to gastric distension induced by duodenal acidification

BACKGROUND AND AIM

Duodenal acidification might increase sensitivity to gastric distension, which seems to play a role in the genesis of dyspeptic symptoms in a subset of patients with functional dyspepsia. The aim of the present study was to investigate the characteristics of dyspeptic symptoms associated with hypersensitivity to gastric distension induced by duodenal acidification.

METHODS

An infusion tube and a barostat bag were positioned in the duodenum and gastric fundus, respectively. Sensitivity to stepwise fundic distensions with severity scoring of the seven dyspeptic symptoms was assessed before and during duodenal acid infusion in 20 healthy subjects.

RESULTS

Acid infusion significantly decreased the pressures and the corresponding wall tensions at the thresholds for discomfort. At the distending level of minimal distending pressure (MDP) + 2 mmHg, significantly higher scores of fullness and bloating were obtained during acid infusion. With distending stimuli of MDP + 4 and 6 mmHg, fullness, bloating, nausea, satiety, epigastric burning and epigastric pain were significantly more severe during acid infusion than before acid infusion. At the level of MDP + 8 mmHg, the severity of epigastric pain was significantly greater, compared with that before acid infusion.

CONCLUSIONS

Duodenal acidification might aggravate dyspeptic symptoms through the induction of hypersensitivity to gastric distension in healthy individuals. Those symptoms are diverse and variable, depending on the strength of the distending stimuli.

Pathways of Chemical Degradation of Polypeptide Antibiotic Bacitracin

We described the main pathways of bacitracin (Bc) decomposition, chromatographically set the position of its major degradation products and evaluated microbiological activity of isolated components of Bc and its degradation products. All processes of Bc decomposition under stress and accelerated test conditions were monitored with HPLC, performed mainly on a new type reversed-phase (RP-18e) monolithic silica column (Chromolith) enabling fast separation times and some of them also on conventional HPLC columns. Diode array detection, preparative HPLC and FAB mass spectrometry were used for identification of individual Bc components. We found that the major decomposition mechanism in water solutions of Bc is oxidation, and in alkaline solutions, deamidation. In oxidation process the components B1, B2 and B3 and A are oxidized into their corresponding oxidative products H1, H2, H3 and F respectively by the same mechanism. A detailed study of oxidative degradation products revealed that HPLC separation with an acid mobile phase caused splitting of peaks of components H2, H3 and F into two peaks but the peak of component H1 did not split due to its special structural properties. For the component A we confirmed gradual formation of desamido product through an intermediate. We found oxidative degradation products of Bc to be relatively stable, and desamido degradation products to be rather unstable. The estimation of kinetics of Bc decomposition was presented with a semi-quantitative model. Microbiological activity of individual isolated active components of Bc was established and the negligible antimicrobial activity of the degradation products was confirmed.

[Study on reflux esophagitis treated by Tongjiang granule]

OBJECTIVE

To study the mechanism of Tongjiang granule on treating GERD.

METHOD

The rats in the model group received steel wire ring-cardiamyopexy. A steel wire ring was fixed firmly on cardia. The rats in the control group underwent the cardia-plasty plus pylori ligation plus stomach-empty intestine Roux-en-Y anastomosis. The rats were divided into six groups after operations at random, which were fed up respectively with Tongjiang granule of different dosage and perpulsid. No treatment groups were taken as control.

RESULT

The experiment showed that Tongjiang granule could lighten or cure RE in the pathology, decrease the hydrochloric acid in gastric juice, in the meantime, increase the motilin in the animal blood. This study indicated that the effect of Tongjiang granule group from experimental research was better than that of the control group (perpulsid).

CONCLUSION

The effects of Tongjiang granule on treating GERD can be achieved by decreasing the hydrochloric acid in gastric juice, increasing the motilin in blood and promoting the gastric impetus in the animal experiment.

In vitro model of acute esophagitis in the cat

We have shown that IL-1beta and IL-6, possibly originating from the mucosa in response to injury, inhibit neurally mediated contraction of esophageal circular muscle but do not affect ACh-induced contraction, reproducing the effect of experimental esophagitis on esophageal contraction. To examine the interaction of mucosa and circular muscle in inflammation, we examined the effect of HCl on in vitro esophageal mucosa and circular muscle. Circular muscle strips, when directly exposed to HCl, contracted normally. However, when circular muscle strips were exposed to supernatants of mucosa incubated in HCl (2-3 h, pH 5.8), contraction decreased, and the inhibition was partially reversed by an IL-6 antibody. Supernatants from the mucosa of animals with in vivo-induced acute esophagitis (AE) similarly reduced contraction. IL-6 levels were higher in mucosal tissue from AE animals than in control mucosa and in AE mucosa supernatants than in normal mucosa supernatants. IL-6 levels increased significantly in normal mucosa and supernatants in response to HCl, suggesting increased production and release of IL-6 by the mucosa. IL-6 increased H2O2 levels in the circular muscle layer but not in mucosa. Exposure of the mucosa to HCl caused IL-1beta to increase only in the mucosa and not in the supernatant. These data suggest that HCl-induced damage occurs first in the mucosa, leading to the production of IL-1beta and IL-6 but not H2O2. IL-1beta appears to remain in the mucosa. In contrast, IL-6 is produced and released by the mucosa, eventually resulting in the production of H2O2 by the circular muscle, with this affecting circular muscle contraction.

Surfactant alterations in acute inflammatory lung injury from aspiration of acid and gastric particulates

This study examines surfactant dysfunction in rats with inflammatory lung injury from intratracheal instillation of hydrochloric acid (ACID, pH 1.25), small nonacidified gastric particles (SNAP), or combined acid and small gastric particles (CASP). Rats given CASP had the most severe lung injury at 6, 24, and 48 h based on decreases in arterial oxygenation and increases in erythrocytes, total leukocytes, neutrophils, total protein, and albumin in bronchoalveolar lavage (BAL). The content of large surfactant aggregates in BAL was reduced in all forms of aspiration injury, but decreases were greatest in rats given CASP. Large aggregates from aspiration-injured rats also had decreased levels of phosphatidylcholine (PC) and increased levels of lyso-PC and total protein compared with saline controls (abnormalities for CASP were greater than for SNAP or ACID alone). The surface tension-lowering ability of large surfactant aggregates on a bubble surfactometer was impaired in rats with aspiration injury at 6, 24, and 48 h, with the largest activity reductions found in animals given CASP. There were strong statistical correlations between surfactant dysfunction (increased minimum surface tension and reduced large aggregate content) and the severity of lung injury based on arterial oxygenation and levels of albumin, protein, and erythrocytes in BAL (P < 0.0001). Surfactant dysfunction also correlated strongly with reduced lung volumes during inflation and deflation (P = 0.0004-0.005). These results indicate that surfactant abnormalities are functionally important in gastric aspiration lung injury and contribute significantly to the increased severity of injury found in CASP compared with ACID or SNAP alone.

[Concentration of hydrochloric acid and pepsin in gastric juice in dogs after starvation and refeeding]

Feeding fogs with meat after a 3-day period of starvation increased hydrochloric acid concentration with subsequent return of the parameter to normal values. Under the same conditions, pepsin concentration decreased and raised up after re-feeding. Histamine administration following the starvation decreased hydrochloric acid concentration with subsequent normalising. In three days after re-feeding and histamine administration, pepsin concentration drooped owing, probably, to a decrease of parietal cell H2-receptor affinity to histamine. Pentagastrin administration after the starvation increased hydrochloric acid concentration. The findings suggest G-cell function inhibition occurring after a 3-day starvation which is important for the stomach mucous membrane protection.

Comparison of the Acid Combinations in Microwave-assisted Digestion of Marine Sediments for Heavy Metal Analyses

Sediments as a tool for monitoring contamination by heavy metals in the environment has long been considered. It is therefore a necessity to produce reliable data for such purposes. Microwave-assisted acid dissolution has proved to be a suitable method for digesting complex matrices, such as sediments. However, due to the infancy of the technique, the procedures are numerous and varied in both the reagents used and microwave conditions. In this study, the efficiency of two recommended acid mixtures, a HNO3-HF mixture and an aqua regia-HF mixture, under the same microwave digestion conditions were compared using certified reference materials. It was observed that the HNO3-HF mixture showed better efficiency than the aqua regia-HF mixture in most of the heavy metals analyzed in all certified reference materials used.

Inactivation of the bovine-spongiform-encephalopathy (BSE) agent by the acid and alkaline processes used in the manufacture of bone gelatine

A validation study was carried out to determine the capacity of the traditional acid and alkaline processes used in the manufacture of bovine bone gelatine to remove and/or inactivate the transmissible agent that causes BSE (bovine spongiform encephalopathy). Using an accurately scaled down laboratory process that precisely mimicked the minimum conditions of the industrial processes, gelatine (gelatin) was manufactured from industrial starting material that had been spiked with mouse brain infected with the 301V strain of mouse-passaged BSE agent. Clearance factors were determined by titrating the infectivity levels of the infected mouse brain tissue, the gelatine extracts, and the final sterilized gelatine solution. The infectivity level of the spiked starting material was 10(8.4) mouse intracerebral ID(50)/kg (ID(50) is the dose at which half of the challenged animals were infected). Clearance factors of 10(2.6) and 10(3.7) ID(50) were demonstrated for the first stages of the acid and alkaline processes respectively during which the bones are converted to crude gelatine. It was further demonstrated that the complete acid and alkaline processes both reduced infectivity to undetectable levels, giving clearance factors of >/=10(4.8) ID(50) for the acid process, and >/=10(4.9) ID(50) for the alkaline process.

Inhibition of gastric H,K-ATPase activity and gastric epithelial cell IL-8 secretion by the pyrrolizine derivative ML 3000

Background

ML 3000 ([2,2-dimethyl-6-(4-chlorophenyl)-7-phenyl-2,3-dihydro-1H-pyrrolizine-5-yl]-acetic acid) is an inhibitor of both cyclooxygenase and 5-lipoxygenase in vitro, and shows promise as a novel non-steroidal anti-inflammatory drug (NSAID). Unlike conventional NSAIDs which are associated with gastric ulcerogenic effects, ML 3000 causes little or no damage to the gastric mucosa, even though it significantly depresses gastric prostaglandin synthesis.

Methods

As part of an effort to clarify mechanisms underlying the gastric sparing properties of ML 3000, we studied the effects of ML 3000 on H,K-ATPase activity in vitro, on acid accumulation in isolated gastric parietal cells, and on IL-8 secretion by gastric epithelial cells in culture.

Results

SCH28080-sensitive H,K-ATPase activity in highly-purified pig gastric microsomes was dose-dependently inhibited by ML 3000 (IC₅₀ = 16.4 μM). Inhibition was reversible, and insensitive to ML 3000 acidification in the pH range 2.0–8.0. In rabbit gastric parietal cells,

ML 3000 dose-dependently inhibited histamine-stimulated acid accumulation (IC₅₀ = 40 μM) and forskolin-stimulated acid accumulation (IC₅₀ = 45 μM). Lastly, in human gastric adenocarcinoma (AGS) cells, ML 3000 dose-dependently inhibited both baseline and IL-1β-stimulated (20 ng/ml) IL-8 secretion with IC₅₀s of 0.46 μM and 1.1 μM respectively.

Conclusion

The data indicate that ML 3000 affects acid-secretory mechanisms downstream of cAMP mobilization induced by histamine H₂ receptor activation, that it directly inhibits H,K-ATPase specific activity, and that baseline gastric epithelial cell IL-8 secretory inhibition may be mediated by ML 3000 inhibition of 5-lipoxygenase activity. We conclude that these gastric function inhibitory data may underlie the gastric sparing properties of ML 3000.

In vitro gastrointestinal digestion study of broccoli inflorescence phenolic compounds, glucosinolates, and vitamin C

Broccoli (Brassica oleracea L. var. italica cv. Marathon) inflorescences are a good source of bioactive compounds, such as phenolics (flavonoids and hydroxycinnamoyl derivatives), glucosinolates, and vitamin C. In this work, these health-promoting compounds were submitted to digestion under in vitro gastrointestinal conditions (pH, temperature, enzyme, and chemical conditions). This technique differentiated among the compounds associated with macromolecules in soluble and insoluble form and those that are freely soluble. In addition, it evaluates the chemical stability of the broccoli compounds under simulated physiological conditions. The gastric digestion of broccoli caused high losses in glucosinolates (69% loss), whereas phenolics and vitamin C presented higher stability under these conditions. Thus, there were no losses in flavonoids, a 7% loss of vitamin C, and a variable rate of loss (6-25%) in hydroxycinnamic acid derivatives. The stability of all of the compounds was affected by the in vitro intestinal conditions. Under the in vitro conditions, flavonoids and hydroxycinnamoyl acid derivatives were of low availability, due to their significant losses under these conditions, at the end of the experiment (84 and 80% loss, respectively). Vitamin C was the metabolite that showed the greater decrease after intestinal digestion (91% loss). Regarding the remaining glucosinolates, these compounds presented higher stability under intestinal conditions, rendering an availability similar to that found for phenolics (75% loss). Therefore, broccoli components were affected by gastric and/or intestinal conditions depending on the type of compound. Thus, glucosinolates were mainly degraded by gastric conditions, whereas phenolic compounds and vitamin C were degraded by intestinal conditions.

[Gastric secretion in dogs following three day fasting and resumed feeding]

The investigation into the influence of a three-day starvation on the gastric secretion in dogs with Pavlov pouches stimulated by meat, histamine and pentagastrin, was carried out. A 72-hour starvation did not change the summary volume of the gastric juice, debit of the gastric acid, and quantity of pepsin. At the same time the starvation decreased the average rate of gastric juice secretion, gastric acid and pepsin secretion in response to histamine and decreased the pepsin secretion in response to pentagastrin. In this way re-feeding enhanced the average rate of gastric juice secretion and gastric acid secretion on 3-day and pepsin on 5-day in response to meat. The average rate of gastric juice secretion increased on the 5-day after refeeding in response to histamine and the average rate of gastric juice, gastric acid and pepsin secretion in response to pentagastrin.

Augmenting effect of acetic acid for acidification on bactericidal activity of hypochlorite solution

AIMS

Bactericidal activity of chlorine solution is enhanced by weak acidification. We compared the effects of various acids on the bactericidal activity of hypochlorite solution to establish a method for safe and effective use of an acidic hypochlorite solution.

METHODS AND RESULTS

The bactericidal activities of acidic hypochlorite solutions that had been adjusted to pH 5.0 with hydrochloric acid, acetic acid, citric acid, lactic acid, formic acid, phosphoric acid or sulphuric acid against Bacillus subtilis spores were compared. The acidic solutions prepared with hydrochloric acid and acetic acid showed the highest bactericidal activity, and all of the spores (5 x 106 cfu ml(-1)) were killed within 10 min. On the other hand, the solutions prepared with citric acid and lactic acid showed no bactericidal activity against any bacterial strains tested in this study despite the low pH. The amount of chlorine gas produced by the preparation using acetic acid was sixfold less than that produced from the preparation using hydrochloric acid.

CONCLUSIONS

Acetic acid is the most suitable and safe acid for the preparation of an acidic hypochlorite solution.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of this study provide useful information for establishing a method for safe and effective use of an acidic hypochlorite solution.

[The biology of aerobic methylobacteria capable of degrading halomethanes]

Recent data on the biology of aerobic methylotrophic bacteria capable of utilizing toxic halogenated methane derivatives as sources of carbon and energy are reviewed, with particular emphasis on the taxonomic, physiological, and biochemical diversity of mono- and dihalomethane-degrading methylobacteria and the enzymatic and genetic aspects of their primary metabolism. The initial steps of chloromethane dehalogenation to formate and HCl through a methylated corrinoid and methyletrahydrofolate are catalyzed by inducible cobalamin methyl transferase, made up of two proteins (CmuA and CmuB) encoded by the cmuA and cmuB genes. At the same time, the primary dehalogenation of dichloromethane to formaldehyde and HCl is catalyzed by cytosolic glutathione transferase with S-chloromethylglutathione as an intermediate. The latter enzyme is encoded by the structural dcmA gene and is under the negative control of the regulatory dcmR gene. In spite of considerable progress in the study of halomethane dehalogenation, some aspects concerning the structural and functional organization of this process and its regulation remain unknown, including the mechanisms of halomethane transport, the release of toxic dehalogenation products (S-chloromethylglutathione, CH2O, and HCl) from cells, and the maintenance of intracellular pH. Of particular interest is quantitative evaluation of the ecophysiological role of aerobic methylobacteria in the mineralization of halomethanes and protection of the biosphere from these toxic pollutants.

Oesophageal intraluminal nitric oxide facilitates the acid-induced oesophago-salivary reflex

BACKGROUND

The present study explores some aspects of the triggering of the acid-induced oesophago-salivary reflex. In addition to hydrogen ions, there are two acid-dependent molecules with messenger potential in the oesophageal lumen: CO2 and NO. The aim of this study was to clarify whether oesophageal NO and CO2 participate in the regulation of salivary neutralizing capacity in response to acid exposure.

METHODS

Healthy volunteers received oesophageal acidification composed of HCl, with NO3-, or HCO3- or NO3- and HCO3- in combination. In a second series of experiments, the exposure period was divided into 2 separate 10-min events. Saliva volume and titratable buffering capacity were used to calculate alkaline secretion.

RESULTS

Salivary alkaline secretion increased markedly following 20 min intraluminal exposure to HCl. The initial part of this response was 22% +/- 2.2% larger (P < 0.05) if NO3- was present. When HCO3- was added, or if NO3- and HCO3- were given simultaneously, the secretory response tended to be lower. The accumulated responses over 70 min to 2 short HCl exposures (10 min each separated by a 30 min 'rest') compared to one long one lasting 20 min were similar regardless of the presence of NO3-.

CONCLUSION

The data suggest that oesophageal intraluminal NO facilitates initiation of the oesophago-salivary reflex. CO2 seems to have a negligible effect on alkaline salivation, and repeated stimulation does not influence the magnitude of the response over time.

Distribution of aflatoxins in product and by-products during glucose production from contaminated corn

Aflatoxins are known to be hepatotoxic, carcinogenic, and teratogenic. A positive correlation has been established between the consumption of aflatoxin-contaminated foods and the increased incidence of liver cancer worldwide. A survey of Egyptian corn and corn-based products and by-products shows that the majority of the samples had higher limits of aflatoxin. We have conducted experiments to determine the fate and distribution of aflatoxin during wet-milling process fractions and investigate the aflatoxin destruction during starch conversion to glucose syrup. The present results showed that about half of the aflatoxin content (48.1%) in the infected corn grain was found to be lost in steep liquor, depending upon the aflatoxin type, arranged in the order G1 > G2 > B1 > B2. After wet-milling aflatoxins were distributed into starch, gluten, fiber, and germ. Gluten, fiber, and germ were the most highly contaminated fractions. The loss of aflatoxin during process of starches reached 54.4% in steep water and water process. Although the gluten fraction represents only 9.6% of corn, the higher percentage (25.3%) of aflatoxin was found in this fraction, the fiber and germ account for nearly 29% of the milled corn and contain 11.6% of the aflatoxin. On the other hand, 8.7% of the total aflatoxins in start corn was found in starch fraction which accounts 61% of the milled corn. Aflatoxins G1 and G2 were found lost in higher concentrations compared to the aflatoxin B1 and B2. A higher percentage of AfG1 (86.35%) and AfG2 (78.36%) and a lower percentage of AfB1 (16.3%) and AfB2 (14.7%) were found in starch fraction. The conversion percent of contaminated starch was 89.5% compared with control starch. It can be concluded that aflatoxins were destroyed during starch conversion. Consequently, glucose syrup produced from contaminated starch was found aflatoxin-free.

Intracellular and extracellular pHs of Streptococcus mutans after addition of acids: loading and efflux of a fluorescent pH indicator in streptococcal cells

A pH-sensitive fluorescent dye, 2', 7'-bis-(2-carboxyethyl)-5 and 6-carboxyfluorescein (BCECF), was used to determine intracellular pH (pH(in)). The efflux of BCECF loaded into oral streptococcal cells was determined after incubation of the cells at 35 degrees C for 20 min in the presence and absence of glucose. In the absence of glucose, the fluorescence of intracellular BCECF in Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius and Streptococcus sobrinus decreased only very slightly, indicating that the dye could be useful for pH(in) determination. In the presence of glucose, however, the fluorescence decreased by 57%. Thus, the pH(in) of S. mutans cells was measured by the BCECF method in the absence of glucose at various acidic pH levels by adding lactic, acetic and hydrochloric acids to the cell suspensions. The pH(in) was almost equal to the extracellular pH (pH(out)) for pH(out) values of between 8 and 5, indicating that protons permeated easily across the S. mutans cell membrane. For pH(out) between 5 and 4, pH(in) was constant at around 5, suggesting that the cell membrane was impermeable to protons, or that a cytoplasmic buffering system functioned. pH(in) decreased at pH(out) values of < 4. The constant pH(in) at acidic pH(out) levels could protect intracellular components, such as proteins, against acidification by sugar fermentation.

Quenching of bathocuproine disulfonate fluorescence by Cu(I) as a basis for copper quantification

In this paper we report the up to now ignored fluorescence properties of the specific Cu(I)-chelator bathocuproine disulfonate and their application in assays of total copper and Cu(I). The method is based on the linear quenching of the bathocuproine disulfonate emission at 770 nm (lambda(ex)580 nm) by increasing concentrations of Cu(I), at pH 7.5. Copper concentrations as low as 0.1 microM can be determined. Other metal ions (iron, manganese, zinc, cadmium, cobalt, nickel) do not interfere. The procedure for total copper determination in proteins includes HCl treatment to release the copper, neutralization to pH 7.5 in the presence of citrate to stabilize the copper, and reduction of the copper to Cu(I) by ascorbate in the presence of the chelator. This assay gave results coincident with the analysis by atomic absorption spectroscopy in two selected proteins. In addition, conditions are described (omitting HCl treatment and reduction by ascorbate) for direct measurement of Cu(I) in native proteins, as illustrated for the Escherichia coli NADH dehydrogenase-2. Data show that the fluorometric assays described in this paper are simple and convenient procedures for total copper and direct Cu(I) quantification in determined biological samples.

Effect of thermal and chemical pretreatments on anaerobic ammonium removal in treating septage using the UASB system

This work investigated how thermal and chemical pretreatments influenced the anaerobic ammonium oxidation process in anaerobic digestion using biogranules that had been acclimated to septage. The digestion experiments were performed in serum vials using thermally and chemically pretreated septage as the substrate. The experimental results indicated that heat pretreatment reduced both dinitrogen production and ammonium removal. HCl and NaOH pretreatments increased both values by near 45% and 55% over the control. Alkali addition was more efficient than acid addition in enhancing dinitrogen production and ammonium removal.

Ion channel formation from a calix[4]arene amide that binds HCl

The ion transport activity of calix[4]arene tetrabutylamide 1,3-alt 2 was studied in liposomes, planar lipid bilayers, and HEK-293 cells. These experiments, when considered together with (1)H NMR and X-ray crystallography data, indicate that calix[4]arene tetrabutylamide 2 (1) forms ion channels in bilayer membranes, (2) mediates ion transport across cell membranes at positive holding potential, (3) alters the pH inside liposomes experiencing a Cl(-) gradient, and (4) shows a significant Cl(-)/SO(4)(2)(-) transport selectivity. An analogue, calix[4]arene tetramethylamide 1, self-assembles in the presence of HCl to generate solid-state structures with chloride-filled and water-filled channels. Structureminus signactivity studies indicate that the hydrophobicity, amide substitution, and macrocyclic framework of the calixarene are essential for HCl binding and transport. Calix[4]arene tetrabutylamide 2 is a rare example of an anion-dependent, synthetic ion channel.

HCl causes less intracellular acidification in Necturus gastric mucosa surface epithelial cells than other acids

Luminal acid causes intracellular acidification in the gastric epithelium, but the mechanism by which H(+) enters surface cells remains obscure. This study addressed the problem by assessing how different acids affect intracellular pH in gastric surface cells. Isolated Necturus maculosus antral mucosa was exposed to HCl, HNO(3), H(2)SO(4), and H(3)PO(4) at pH 2.30. Intracellular pH was measured with microelectrodes. The physicochemical interaction of a synthetic model of gastric phospholipids with the different acids was studied using Langmuir film balance. Exposure to luminal HNO(3), H(2)SO(4), or H(3)PO(4) caused significantly larger intracellular acidification than exposure to HCl. The degree of acidification was not dependent on the valence or nature of the anionic counterion of the acid but significantly correlated with the amount of molecular acid. By Langmuir film balance, subphases acidified with HNO(3), H(2)SO(4), or H(3)PO(4) caused more close packing of phospholipid molecules than those acidified with HCl, possibly allowing hydrogen bonding between head groups to facilitate H(+) movement across the phospholipid membrane. HCl causes significantly less intracellular acidification in gastric epithelium than HNO(3), H(2)SO(4), or H(3)PO(4). This may be caused by the lower amount of molecular HCl in solution and possible hydrogen bonding between the head groups of phospholipid molecules and the other acids.

Acid regulates inflammatory response in a rat model of induction of gastric ulcer recurrence by interleukin 1beta

BACKGROUND

In a previous study we showed that interleukin 1beta (IL-1beta) caused recurrence of gastric ulcers in rats, and that adhesion molecules (intercellular adhesion molecule 1 and leucocytic beta2 integrins) play a role in this recurrence. Although gastric acid plays an important role in many types of gastric injuries, including peptic ulcer recurrence, the mechanism(s) remains unclear.

AIMS

To examine the involvement of gastric acid in induction of ulcer recurrence by IL-1beta, and to investigate the role of gastric acid in inflammatory responses during ulcer recurrence.

METHODS

Rats with healed ulcers were used. Rats were given 1 microg/kg IL-1beta intraperitoneally. Another group of rats was given 20 mg/kg omeprazole for three days to inhibit acid secretion, and received IL-1beta 20 hours after the first administration of omeprazole. They were then given 0.15 N HCl or vehicle at 0, 12, 24, and 36 hours after IL-1beta treatment. Some rats were given acid alone at the same time points. Expression of adhesion molecules was examined immunohistochemically and concentrations of IL-1beta and tumour necrosis factor alpha (TNF-alpha) were measured by ELISA in scar tissue 24 hours after IL-1beta treatment.

RESULTS

IL-1beta increased expression of adhesion molecules and concentrations of IL-1beta and TNF-alpha in scar tissue by 24 hours after IL-1beta treatment, and nine of 11 healed ulcers had recurred by 48 hours. Omeprazole inhibited the effects of IL-1beta. HCl acid abolished the inhibitory effects of omeprazole. Acid alone affected neither expression of adhesion molecules nor cytokine concentrations, and did not cause recurrence.

CONCLUSIONS

Gastric acid is required for recurrence of gastric ulcers caused by IL-1beta, and gastric acid stimulates the inflammatory process in scarred mucosa during ulcer recurrence.

NH(4)Cl inhibition of acid secretion: possible involvement of an apical K(+) channel in bullfrog oxyntic cells

This study was undertaken to determine the mechanism by which ammonium chloride (NH(4)Cl) inhibits stimulated acid secretion in the bullfrog gastric mucosa. To this end, four possible pathways of inhibition were studied: 1) blockade of basolateral K(+) channel, 2) blockade of ion transport activity, 3) neutralization of secreted H(+) in the luminal solution, or 4) ATP depletion. Addition of nutrient 10 mM NH(4)Cl (calculated NH(3) concentration = 92.5 microM and NH(4)(+) concentration = 9.91 mM) inhibited acid secretion within 30 min. Inhibition of acid secretion did not occur by blockade of basolateral K(+) channel activity or ion transport activity or by neutralization of the luminal solution. Although ATP depletion occurred in the presence of NH(4)Cl, the magnitude of ATP depletion in 30 min was not sufficient to inhibit stimulated acid secretion. By comparing the effect of NH(4)Cl on the resistance of inhibited or stimulated tissues, we demonstrate that NH(4)Cl acts specifically on stimulated tissues. We propose that NH(4)Cl blocks activity of an apical K(+) channel present in stimulated oxyntic cells. Our data suggest that the activity of this channel is important for the regulation of acid secretion in bullfrog oxyntic cells.

Effects of rabbit gastrointestinal mucins and dextran on hydrochloride diffusion in vitro

We compared a viscous fingering formation of hydrochloric acid (HCl) in rabbit corpus, antral and duodenal mucins and with dextran under neutral and acidic conditions with respect to relative viscosity, molecular mass, and carbohydrate composition. The effect of desialyzation of duodenal mucin on the viscous fingering formation of HCl was also examined. HCl (0.1 N) was injected into 1% solutions of mucins and dextran and a subsequent viscous fingering formation was assessed based on an influx volume rate of HCl. A low influx volume rate indicates a high ability of the solutions to produce viscous fingers. The influx volume rate of HCl was lowest in duodenal mucin followed bl corpus mucin, antral mucin, and dextran at pH 7. The influx volume rate of HCl was inversely correlated with the relative viscosity of the solution. Maximum molecular masses were large in the order of corpus, antral, and duodenal mucins, and they were larger than dextran T2000. Rabbit gastrointestinal mucins were very polydisperse system. Duodenal mucin contains more sialic acid than gastric mucins; the influx volume rate of HCl increased in desialylated duodenal mucin. It is suggested that the higher ability of gastric mucins to prevent HCl diffusion than dextran were due to the differences in the molecular mass. The ability of duodenal mucin to prevent HCl diffusion was probably attributed to its high sialic acid content, which may reflect a physiological role of duodenal mucin in the duodenum that has to deal with HCl influx from the stomach.

Possible involvement of undissociated acid molecules in the acid response of the chorda tympani nerve of the rat

To test whether undissociated acid is capable of exciting the chorda tympani nerves in rats, we have used buffered acid solutions as taste stimuli. These solutions were prepared by adding alkali to weak acids, such as acetic acid, so that the proportion of undissociated and dissociated acids was varied whereas keeping the total acid concentration constant. When acetic acid solutions, adjusted to wide ranges of pH by NaOH, were applied to the tongue, the response magnitude of the chorda tympani nerves was not varied systematically with pH changes. However, if the sodium effect was eliminated by amiloride or replacement of cation by potassium or Tris[hydroxymethyl]aminomethane; NH(2)C(CH(2)OH)(3) (Tris-base), the chorda tympani response was reduced systematically as pH increased. Similar results were obtained with citric acid and ascorbic acid. This pH-dependent change in taste nerve response to acid cannot be solely attributed to the proton gradient because the response magnitude induced by hydrogen itself, which was estimated from responses to strong acids, was much smaller than that by equi-pH acetic acid ( approximately 85%). Thus we cannot explain the pH-dependent responses of the chorda tympani nerves to weak acids unless effects of undissociated acid molecules are postulated. It is therefore concluded that undissociated acids in weak acid solutions can be a stimulant to taste receptor cells.

Flow injection atomic absorption spectrometric determination of iodide using an on-line preconcentration technique

A continuous flow atomic absorption spectrometric system was used to develop an efficient on-line preconcentration-elution procedure for the determination of iodide traces. Chromium (VI) is introduced into the flow system and is reduced to chromium (III) in acid medium proportionally to the iodide present in the sample. The Cr(III) reduced by iodide is retained on a minicolumn packed with a poly(aminophosphonic acid) chelating resin, while unreduced Cr(VI) is not retained. Reduced Cr(III) is preconcentrated by passing the sample containing iodide through the system during 3 min, and is then eluted with 0.5 mol L(-1) hydrochloric acid and determined by flame atomic absorption spectrometry (FAAS). The detection limit (3sigma) obtained is 2.5 microg L(-1). Other ions typically present in waters do not interfere. The proposed method allows the determination of iodide in the range 6-220 microg L(-1) with a relative standard deviation of 2.7% at a rate of 17 samples h(-1). The method has been applied to the determination of iodide in tap and sea waters.

Mechanism of the hypotensive action of Rhazya stricta leaf extract in rats

The hypotensive action of Rhazya stricta lyophilized leaf extract was found to be partly caused by the electrolyte content of the extract, and partly caused by a strongly basic alkaloidal fraction (AF). AF (0.05-1.6 mg animal(-1)) caused a dose-dependent reduction in mean arterial blood pressure (MAP) of urethane-anaesthetized rat preparations. In naiuml;ve pithed rats, AF administration (0.5-2.0 mg animal(-1)) significantly increased MAP. In pithed or spinalized rats made normotensive by noradrenaline infusion, AF (0.25 mg animal(-1)) did not cause any significant changes. Direct intracerebroventricular injection of AF (0.1-0.4 mg) markedly and significantly reduced MAP. It is suggested that the hypotensive action of AF to be mediated by a central mechanism.