Mechanisms involved in the gastroprotective activity of esculin on acute gastric lesions in mice

This work describes the gastroprotective actions of esculin (6,7-dihydroxycoumarin-6-o-glucoside) against indomethacin- or ethanol-induced lesions and verifies the role of nitric oxide, ATP-dependent K⁺ channels, prostaglandins, transient receptor potential vanilloid 1 and antioxidant effects in the gastroprotective mechanism of esculin in the ethanol-induced gastric lesion model. The intragastric administration of esculin at doses of 12.5, 25 and 50 mg/kg was able to protect the gastric mucosa against ethanol (0.2 mL/animal p.o.), and esculin at doses of 25 and 50 mg/kg protected against indomethacin-induced lesions (20 mg/kg p.o.). Administration of l-NAME (10 mg/kg i.p.), glibenclamide (10 mg/kg i.p.) or indomethacin (10 mg/kg p.o.), but not capsazepine (5 mg/kg p.o.), was able to reduce the gastroprotection promoted by esculin (25 mg/kg) on the ethanol-induced lesions. Measurements of nitrite, a NO metabolite, were increased in the group that was pretreated with esculin. In terms of antioxidant activity as a gastroprotective mechanism of esculin, the results show that pre-treatment with esculin decreased the amount of GSH, increased SOD activity, did not interfere with the CAT activity and decreased both the MPO activity and the MDA amount. In conclusion, pre-treatment with esculin confers significant gastroprotective and antioxidant activity and leads to a reduction in gastric injury; the mechanisms underlying these effects include stimulation of endogenous prostaglandins, nitric oxide synthesis, opening of K_ATP channels and reduction of free radicals or modulation of antioxidant enzyme systems.     

Protective role of ellagitannins from Eucalyptus citriodora against ethanol-induced gastric ulcer in rats: Impact on oxidative stress,inflammation and calcitonin-gene related peptide

The gastroprotective activity of an ellagitannin-rich fraction obtained from Eucalyptus citriodora (ECF) was investigated against ethanol-induced gastric ulceration in rats. The rats were pretreated with ECF (25, 50 and 100 mg/kg) 1 h before the administration of absolute ethanol to induce acute gastric ulceration. The gastric lesions were significantly reduced by all doses of ECF. Notably, pre-treatment with ECF (100 mg/kg) conferred 99.6% gastroprotection, which is significantly higher than that produced by omeprazole. Moreover, ECF administration markedly increased the mucin content in a dose-dependent manner. The potent gastroprotective effect of ECF could be partly mediated by attenuating ethanol-induced oxidative stress. ECF-pre-treatment markedly increased the depleted GSH and SOD levels in a dose-dependent manner. Moreover, ECF significantly decreased the elevated MDA tissue levels induced by ethanol administration. The results demonstrated that ECF administration exerted a powerful anti-inflammatory activity as evidenced by the reduction in the pro-inflammatory markers; IL-1β, TNF-α, 5-LO and COX-2. Additionally, the caspase-3 tissue levels were significantly reduced in the groups pre-treated with ECF. These results suggest that ECF could exert a beneficial gastroprotective effect through their antioxidant, anti-inflammatory and anti-apoptotic properties. Furthermore, ECF pre-treatment significantly attenuated the ethanol-induced decrease in CGRP expression, which has a protective role against gastric ulceration. Histopathological examination revealed intact mucosal layer, absence of hemorrhage and necrosis in groups treated with ECF. Ellagitannins were identified as the major active constituents responsible for the marked antioxidant and gastroprotective properties of ECF. The HPLC–PDA–ESI/MS/MS technique was employed to identify the ellagitannins of E. citriodora.     

Gastroprotective mechanisms of Citrus lemon (Rutaceae) essential oil and its majority compounds limonene and β-pinene: involvement of heat-shock protein-70, vasoactive intestinal peptide, glutathione, sulfhydryl compounds, nitric oxide and prostaglandin E₂

Citrus lemon (CL) belongs to Rutaceae family and is popularly known in Brazil as limão siciliano. The phytochemical analysis of CL fruit bark essential oil showed two majority components, limonene (LIM) and β-pinene (PIN). This study aimed to evaluate the gastroprotective mechanism of action from CL, LIM and PIN in ethanol- and indomethacin-induced gastric ulcers and its in vitro anti-Helicobacter pylori activity. After ethanol-induced gastric ulcer, the ulcer area was measured and the stomachs were destined to histology (HE and PAS), immunohistochemistry for HSP-70 and VIP and glutathione (GSH) measurement. The involvement of nitric oxide (NO) and sulfhydryl (SH) compounds was determined. The ulcer area for indomethacin-induced gastric ulcers was measured. PGE₂ concentration was biochemically measured. The minimum inhibitory concentration (MIC) against H. pylori was determined in vitro. In ethanol model, CL and LIM demonstrated 100% of gastroprotection, while PIN did not exert effective gastroprotection (53.26%). In the indomethacin model, CL and LIM offered effective gastroprotection but PIN did not show gastroprotective effect. The gastric ulcer area of rats pretreated with NO-synthase inhibitor or SH-blocker was decreased in comparison to the control group. The MIC obtained for CL was 125 μg/mL, for LIM was 75 μg/mL and for PIN was 500 μg/mL. The gastroprotective effect of CL and LIM was involved with increasing in mucus secretion, HSP-70 and VIP, but not with GSH, NO or SH compounds. CL gastroprotective mechanism is involved with PGE₂. PIN did not present gastroprotective activity.     

Healing potential of Pequi (Caryocar coriaceum Wittm.) fruit pulp oil

Caryocar coriaceum Wittm. (Caryocaraceae), popularly known as Pequi, is a common tree frequently used in folk medicine to treat many types of afflictions, such as wound lesions, gastric and inflammatory diseases. The present study was undertaken to evaluate the healing potential of the pulp oil from C. coriaceum (OCC) in rats and mice. OCC was tested by monitoring wound contraction in incised wounds and topical application of OCC accelerated wound contraction in open wounds. The mean values of wound contraction in pulp oil treated rats on day 16 were 6.25 ± 0.51% as against 4.17 ± 0.28% seen in control and the difference was statistically significant (p < 0.01). Gastric lesions induced by ethanol and aspirin were significantly reduced by OCC (200 and 400 mg/kg, p < 0.05). Pretreatment of mice with yohimbine, indomethacin, l-NAME or glibenclamide greatly suppressed the gastroprotective effect of OCC. Thus we provide the first evidence that OCC reduces gastric damage induced by ethanol, at least in part, by mechanisms that involve α₂-receptors, endogenous prostaglandins, nitric oxide and K⁺ATP channels. These results indicate the beneficial effect of C. coriaceum on wound and gastric healing and justify its traditional use for the treatment of wounds and gastric ulcers.     

Role of polyamines in gastroprotection induced by epidermal growth factor.

Polyamines have been shown to stimulate cellular growth and differentiation, though their role in the prevention of acute gastric lesion induced by various noxious agents has been little studied. Epidermal growth factor (EGF) exhibits gastroprotective and ulcer healing properties due to its potent mitogenic and growth promoting action. This study was designed to compare the gastroprotective effects of spermine and EGF against gastric damage induced by absolute ethanol, acidified aspirin and stress and to determine the role of endogenous polyamines in EGF-induced gastroprotection. Spermine and EGF significantly reduced the lesions induced by all three ulcerogens. Oral administration of spermine or subcutaneous infusion of EGF in 24 h fasted rats with chronic gastric fistula resulted in similar inhibition of gastric acid and pepsin secretion. Pretreatment with difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), a key enzyme in the biosynthesis of polyamines, did not affect ethanol lesions, but reversed the protective effect EGF but not spermine against ethanol. This finding indicates that polyamines mediate, at least in part, EGF-induced gastroprotection. In tests with oral administration of aminoguanidine that is known to suppress the activity of diamino-oxidase (DAO) and to inhibit the degradation of polyamines, EGF showed a markedly enhanced gastroprotective activity against ethanol damage. Since indomethacin failed to affect the gastroprotective effects of spermine and EGF and neither of these agents influenced the mucosal generation of PGE2 in intact or injured gastric mucosa, we conclude that prostaglandins are not the major factors in spermine- and EGF-induced gastroprotection. This study demonstrates that polyamines are highly effective against gastric lesions induced by various ulcerogens and that they act as primary mediators of EGF-induced gastroprotection.     

Adaptation of rat gastric tissue against indomethacin toxicity

Indomethacin is used in the treatment of inflammatory diseases. But the drug toxicity limits its usage. This study investigated whether adaptation occurred after various dosages of repeated (chronic) indomethacin in rats to the gastro-toxic effects of indomethacin. It also examined whether the adaptation was related to oxidant–antioxidant mechanisms and oxidative DNA damage in gastric tissue. To illuminate the adaptation mechanism in the gastric tissue of rats given various dosages of chronic indomethacin, the levels of oxidants and antioxidants (GSH, MDA, NO, SOD and MPO), activities of COX-1 and COX-2 enzymes and oxidative DNA damage (8-OHd Gua/10⁵ Gua) were measured. Results were compared to 25-mg/kg single-dose indomethacin group, and the role of oxidant and antioxidant parameters and oxidative DNA damage in the adaptation mechanism was evaluated. The average ulcer areas of gastric tissue of the 0.5-, 1-, 2-, 3-, 4-, and 5-mg/kg dosages of chronic indomethacin given to rats were 19.5 ± 3.7, 12.5 ± 3.3, 10 ± 5.2, 4.5 ± 3.6, 8.6 ± 2.4, and 9.5 ± 2.1 mm², respectively. This rate was measured as 21.3 ± 2.6 mm² in the single-dose indomethacin group. Consequently, after various dosages of repeated (chronic) indomethacin administration in rats, it was observed that a clear adaptation developed against gastric damage and that gastric damage was reduced. The best adaptation was observed in the gastric tissue of the 3-mg/kg chronic indomethacin group. In parallel with the damage reduction, the oxidant parameters (MDA and MPO) and oxidative DNA damage (8-OHd Gua/10⁵ Gua) were reduced, and the antioxidant parameters (GSH, NO and SOD) were increased. There is no relation between COX enzymes and adaptation mechanism. This circumstance shows that not COX-1 and COX-2 enzymes, oxidant and antioxidant parameters may play a role in the adaptation mechanism.     

The effect of trans-ferulic acid and gamma-oryzanol on ethanol-induced liver injury in C57BL mouse

The effects of the oral administration of trans-ferulic acid and gamma-oryzanol (mixture of steryl ferulates) with ethanol (5.0 g per kg) for 30 days to c57BL mice on ethanol-induced liver injury were investigated. Preventions of ethanol-induced liver injury by trans-ferulic acid and gamma-oryzanol were reflected by markedly decreased serum activities of plasma aspartate aminotransferase, alanine aminotransferase and significant decreases in hepatic lipid hydroperoxide and TBARS levels. Furthermore, the trans-ferulic acid- and gamma-oryzanol-treated mice recovered ethanol-induced decrease in hepatic glutathione level together with enhancing superoxide dismutase activity. These results demonstrate that both trans-ferulic acid and gamma-oryzanol exert a protective action on liver injury induced by chronic ethanol ingestion.     

Inhibition of CYP2E1 attenuates chronic alcohol intake-induced myocardial contractile dysfunction and apoptosis

Alcohol intake is associated with myocardial contractile dysfunction and apoptosis although the precise mechanism is unclear. This study was designed to examine the effect of the cytochrome P450 enzyme CYP2E1 inhibition on ethanol-induced cardiac dysfunction. Adult male mice were fed a 4% ethanol liquid or pair-fed control diet for 6 weeks. Following 2 weeks of diet feeding, a cohort of mice started to receive the CYP2E1 inhibitor diallyl sulfide (100 mg/kg/d, i.p.) for the remaining feeding duration. Cardiac function was assessed using echocardiographic and IonOptix systems. Western blot analysis was used to evaluate CYP2E1, heme oxygenase-1 (HO-1), iNOS, the intracellular Ca^2 + regulatory proteins sarco(endo)plasmic reticulum Ca^2 +-ATPase, Na⁺Ca^2 + exchanger and phospholamban, pro-apoptotic protein cleaved caspase-3, Bax, c-Jun-NH₂-terminal kinase (JNK) and apoptosis signal-regulating kinase (ASK-1). Ethanol led to elevated levels of CYP2E1, iNOS and phospholamban, decreased levels of HO-1 and Na⁺Ca^2 + exchanger, cardiac contractile and intracellular Ca^2 + defects, cardiac fibrosis, overt O₂^? production, and apoptosis accompanied with increased phosphorylation of JNK and ASK-1, the effects were significantly attenuated or ablated by diallyl sulfide. Inhibitors of JNK and ASK-1 but not HO-1 inducer or iNOS inhibitor obliterated ethanol-induced cardiomyocyte contractile dysfunction, substantiating a role for JNK and ASK-1 signaling in ethanol-induced myocardial injury. Taken together, these findings suggest that ethanol metabolism through CYP2E1 may contribute to the pathogenesis of alcoholic cardiomyopathy including myocardial contractile dysfunction, oxidative stress and apoptosis, possibly through activation of JNK and ASK-1 signaling.     

Ethanol-Induced Gastric Injury: Microscopic Analysis of the Protective Effect of Frutalin

Obtained from breadfruit seeds (Artocarpus incisa), frutalin (FTL) has a range of important pharmacological properties. FTL activates and modulates lymphocytes and neutrophils and possesses gastroprotective effects. The purpose of this study was to evaluate the ability of FTL to protect the gastric mucosa of mice submitted to ethanol-induced gastric injury. The gastroprotective effect of frutalina was evaluated using a murine model of ethanol-induced gastric injury. Damage of the gastric mucosa was assessed morphologically by light, scanning electron and atomic force microscopy. Lymphocyte infiltration, necrosis, disruption of the mucosal structures and epithelial desquamation were observed in the control group. In the group pretreated with frutalina at 0.5 mg/kg, gastroprotection, reduced tissue damage and preserved submucosal and mucosal structures were observed. In conclusion, FTL displayed gastroprotective activity against ethanol-induced gastric injury, preventing the formation of gastric ulcer and reducing epithelial desquamation, glandular damage, mucosal necrosis and infiltration. The observed effects appear to be due to mechanisms previously described for frutalin.     

Antiulcerogenic activity of the hydroalcoholic extract of leaves of Annona muricata Linnaeus in mice

Annona muricata Linnaeus, popularly known as “graviola” and also called soursop, is a species typical of countries with a tropical climate, and it is used in folk medicine as an anticancer, analgesic and antispasmodic agent. The aim of the present study was to validate the gastroprotective activity of the hydroalcoholic extract of the leaves of A. muricata (HEAM) and to investigate the underlying mechanisms of action for this effect. Gastric lesions were induced in mice by absolute ethanol, acidified ethanol or indomethacin. Before, the animals were pretreated with saline, omeprazole or HEAM orally at doses of 50–400 mg/kg. To determine the mechanism of action of the extract, we investigated, using specific inhibitors, the involvement of nitric oxide (NO), prostaglandins (PGEs), ATP-dependent K⁺ channels and α2-noradrenergic receptors. HEAM showed significant antiulcer activity against lesions induced by absolute ethanol, acidified ethanol or indomethacin, which was mediated by endogenous gastric prostaglandins.     

Synergistic effect of Se-methylselenocysteine and vitamin E in ameliorating the acute ethanol-induced oxidative damage in rat

The present study was conduced to investigate the synergistic effects of combined treatments with Se-methylselenocysteine (SeMSC) and vitamin E (Vit E) in reversing oxidative stress induced by ethanol in serum and different tissues of rats. Sixty female rats were randomly divided into six groups for 30 days’ consecutive pretreatments as followed: control (I), physiological saline (II), 2.8 μg kg⁻¹ Se as SeMSC (III), 2.8 μg kg⁻¹ Se as sodium selenite (Na₂SeO₃, IV), 5 mg kg⁻¹ α-tocopherol as α-tocopherol acetate (Vit E, V), 5 mg kg⁻¹ α-tocopherol as α-tocopherol acetate and 2.8 μg kg⁻¹ Se as SeMSC (VI). All animals in groups II–VI were treated by ethanol treatment to cause oxidative stress. After 6 h of ethanol treatment, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), the contents of total antioxidant capacity (T-AOC), malondialdehyde (MDA), glutathione (GSH) and carbonyl protein (CP) in the serum, liver, heart and kidney were measured. The result showed that the individual SeSMC, Na₂SeO₃ and vitamin E could effectively increase the SOD, T-AOC, GSH-Px and GSH contents as well as significantly decrease the MDA and CP concentrations in the tissues of ethanol-induced rats. At the same dose on different forms of Se, SeMSC showed greater antioxidant activity than Na₂SeO₃. Moreover, group VI (SeMSC and α-tocopherol acetate) showed much better antioxidant activity than individual group III (SeMSC) and V (α-tocopherol acetate) due to the synergistic effect.     

Ability of a perfluoropolymer membrane to tolerate by-products of ethanol fermentation broth from dilute acid-pretreated rice straw

A perfluoropolymer (PFP) membrane has been prepared for use in vapor permeation to separate aqueous ethanol mixtures produced from rice straw with xylose-assimilating recombinant Saccharomyces cerevisiae. PFP membranes commonly have been used for dehydration process and possess good selectivity and high permeances. The effects of by-products during dilute acid pretreatment, addition of yeast extract, and ethanol fermentation on PFP membrane performance were investigated. While feeding mixtures of ethanol (90 wt%) in water, to which individual by-products (0.1–2 g/L) were added, the PFP membrane demonstrated no clear change in permeation rate (439–507 g m⁻² h⁻¹) or separation factor (14.9–23.5) from 2 to 4 h of the process. The PFP membrane also showed no clear change in permeation rate (751–859 g m⁻² h⁻¹) or separation factor (12.5–13.8) while feeding the mixture (final ethanol conc.: 61 wt%) of ethanol and distillation of the fermentation broth using a suspended fraction of dilute acid-pretreated rice straw for 20 h. These results suggest that the PFP membrane can tolerate actual distillation liquids from ethanol fermentation broth obtained from lignocellulosic biomass pretreated with dilute acid.     

Nicotine improves ethanol-induced memory impairment: The role of dorsal hippocampal NMDA receptors

AimsThe current study was undertaken to determine the role of dorsal hippocampal N-methyl-d-aspartate (NMDA) receptors in nicotine's effect on impairment of memory by ethanol.Main methodsAdult male mice were cannulated in the CA1 regions of dorsal hippocampi and trained on a passive avoidance learning task for memory assessment.Key findingsWe found that pre-training intraperitoneal (i.p.) administration of ethanol (0.5 and 1 g/kg) decreased memory retrieval when tested 24 h later. Pre-test administration of ethanol reversed the decrease in inhibitory avoidance response induced by pre-training ethanol. Similar to ethanol, pre-test administration of nicotine (0.125–0.75 mg/kg, s.c.) prevented impairment of memory by pre-training ethanol. In the animals that received ethanol (1 g/kg, i.p) before training and tested following intra-CA1 administration of different doses of NMDA (0.0005–0.005 µg/mouse), no significant change was observed in the retrieval latencies. Co-administration of the same doses of NMDA with an ineffective dose of nicotine (0.125 mg/kg, s.c.) significantly improved the memory retrieval and mimicked the effects of pre-test administration of a higher dose of nicotine. Pre-test intra-CA1 microinjection of MK-801 (0.25–1 µg/mouse), which had no effect alone, in combination with an effective dose of nicotine (0.75 mg/kg, s.c.) prevented the improving effect of nicotine on memory impaired by pre-training ethanol. Moreover, intra-CA1 microinjection of MK-801 reversed the NMDA-induced potentiation of the nicotine response.SignificanceThe results suggest the importance of NMDA glutamate system(s) in the CA1 regions of dorsal hippocampus for improving the effect of nicotine on the ethanol-induced amnesia.     

Subcritical water and dilute acid pretreatments for bioethanol production from Melaleuca leucadendron shedding bark

The feasibility of bioethanol production using the lignocellulose of the shedding bark of Melaleuca leucadendron (Paper bark tree) was investigated. The effects of pretreatment parameters (temperature, time and acid concentration) on the yields of sugars and inhibitors, and optimal pretreatment conditions were determined. At very low severity conditions (combined severity factor, CSF ≤ 0.335), 28% of xylan was recovered and this recovery increased with increasing CSF till it peaked to 64.4% (11.2 g xylose L⁻¹) at a CSF of 1.475. However, at CSF > 2.0, xylose yield declined due to degradation. Mild and progressive glucose yield was detected in prehydrolysate at CSF ≥ 1.514, and subsequent enzymatic hydrolysis allowed complete glucan solubilization. Implementing environmentally friendly subcritical water pretreatment at CSF ≤ 0.335 on the shedding bark, about 85% of glucan solubilization was achieved after enzymatic hydrolysis. An industrial Saccharomyces cerevisiae strain readily fermented crude hydrolysate within 12 h, yielding 24.7 g L⁻¹ ethanol at an inoculum size of 2% (v/v), representing a glucose to ethanol conversion rate of 0.475 g g⁻¹ (91% ethanol yield). Based on our findings, the shedding bark is a potential feedstock for bio-ethanol production.     

Effects of feed sugar concentration on continuous ethanol fermentation of cheese whey powder solution (CWP)

Cheese whey powder (CWP) solution with different CWP or sugar concentrations was fermented to ethanol in a continuous fermenter using pure culture of Kluyveromyces marxianus (DSMZ 7239). Sugar concentration of the feed CWP solution varied between 55 and 200 g l⁻¹ while the hydraulic residence time (HRT) was kept constant at 54 h. Ethanol formation, sugar utilization and biomass formation were investigated as functions of the feed sugar concentration. Percent sugar utilization and biomass concentrations decreased and the effluent sugar concentration increased with increasing feed sugar concentrations especially for the feed sugar contents above 100 g l⁻¹. Ethanol concentration and productivity (DP) increased with increasing feed sugar up to 100 g l⁻¹ and then decreased with further increases in the feed sugar content. The highest ethanol concentration (3.7%, v v⁻¹) and productivity (0.54 gE l⁻¹ h⁻¹) were obtained with the feed sugar content of 100 g l⁻¹ or 125 g l⁻¹. The ethanol yield coefficient (Y_P/S) was also maximum (0.49 gE gS⁻¹) when the feed sugar was between 100 and 125 g l⁻¹. The growth yield coefficient (Y_X/S) decreased steadily from 0.123 to 0.063 gX gS⁻¹ when the feed sugar increased from 55 to 200 g l⁻¹ due to adverse effects of high sugar contents on yeast growth. The optimal feed sugar concentration maximizing the ethanol productivity and sugar utilization was between 100 and 125 g l⁻¹ under the specified experimental conditions.     

Combined effect of bone marrow derived mesenchymal stem cells and nitric oxide inducer on injured gastric mucosa in a rat model

AimTo study the effect of intravenous injection of bone marrow mesenchymal stem cells (BMMSCs), alone and combined with NO inducer in gastric ulcer healing in a rat model.MethodsRats were divided into controls, gastric ulcer, gastric ulcer receiving mesenchymal stem cells (MSCs), gastric ulcer receiving NO inducer (l-Arginine), gastric ulcer receiving MSCs plus NO inducer (l-Arginine) groups. MSCs were given in a dose of (10⁶cells) by intravenous injection. l-Arginine was given 300 mg/kg body weight intraperitoneally. 24 h and 7 days after BMMSCs and NO inducer injection, VEGF, PGE, TNF-α were assessed by ELISA. Gene expression of HGF, caspase-3, eNOS and BAX/Bcl-2 in gastric tissues were studied by real time PCR. Histopathology staining of gastric tissues was performed.ResultsInjection of MSCs or NO inducer or both to the gastric ulcer group significantly decreased caspase-3 and BAX genes expression (apoptotic factors) and increased Bcl-2 gene expression (anti-apoptotic factor) compared to that of the gastric ulcer group after both 24 h and 7 days with more significant results in the gastric group received both MSCs and NO inducer. HGF gene expression was significantly increased in the groups injected with MSCs or NO inducer or both compared with the corresponding gastric ulcer group (p < 0.05, p < 0.05 & p < 0.001 respectively). There was a significant decrease in the mean PGE2 and TNF-α levels in the gastric ulcer group receiving MSCs, the gastric ulcer group receiving NO and the gastric ulcer group receiving both MSCs and  NO compared to the gastric ulcer group after both 24 h and 7 days. Histopathological examination of gastric tissue of groups that received stem cells or NO alone, showed mucosal regenerative changes with increased thickness together with reduced inflammatory cellular infiltrate in the submucosa and decreased congestion. There was complete restoration in gastric mucosa in the group that received both stem cells and NO.ConclusionAdministration of MSCs, NO, or MSCs plus NO may exert a therapeutic effect on the mucosal lesion in gastric ulcer through their anti-inflammatory, angiogenic and antiapoptotic actions.     

Application of an integrated statistical design to optimize the cold enzyme hydrolysis conditions for ethanol production

Cold enzyme hydrolysis was investigated on the ethanol production by Saccharomyces cerevisiae during simultaneous saccharification and fermentation (SSF) processing. An integrated statistical design, which incorporated single factor design, response surface methodology (RSM) and weighting coefficient method, was used to determine the optimum hydrolysis conditions leading to maximum biomass, ethanol concentration and starch utilization ratio. After the studied ranges of α-amylase, glucoamylase and liquefaction time were identified by single factor design, RSM was used to further optimize the hydrolysis conditions for each objective. The results showed that, under hydrolysis condition optimized with RSM, biomass, ethanol concentration and starch utilization ratio reached 4.401 ± 0.042 × 10⁸ cells/ml, 14.81 ± 0.23% (wt.%) and 94.52 ± 0.53%, respectively. Finally, multi-objective optimization (MOO) was applied to obtain a compromised result of three desirable responses by weighting coefficient methodology. Biomass of 4.331 ± 0.038 × 10⁸ cells/ml, ethanol concentration of 14.12 ± 0.21% (wt.%) and starch utilization ratio of 92.88 ± 0.21% were simultaneous obtained when hydrolysis at pH 5.9 for 114 min with 233 IU/g_starch α-amylase and 778 IU/g_starch glucoamylase. The optimized conditions were shown to be feasible and reliable through verification tests.     

Radiation damage effects at four specimen temperatures from 4 to 100 K

Radiation damage is the primary factor that limits resolution in electron cryo-microscopy (cryo-EM) of frozen-hydrated biological samples. Negative effects of radiation damage are attenuated by cooling specimens to cryogenic temperatures using liquid nitrogen or liquid helium. We have examined the relationship between specimen temperature and radiation damage across a broad spectrum of resolution by analyzing images of frozen-hydrated catalase crystal at four specimen temperatures: 4, 25, 42, and 100 K. For each temperature, “exposure series” were collected consisting of consecutive images of the same area of sample, each with 10 e^?/Ų exposure per image. Radiation damage effects were evaluated by examining the correlation between cumulative exposure and normalized amplitudes or IQ values of Bragg peaks across a broad range of resolution (4.0–173.5 Å). Results indicate that for sub-nanometer resolution, liquid nitrogen specimen temperature (100 K) provides the most consistent high-quality data while yielding statistically equivalent protection from radiation damage compared to the three lower temperatures. At lower resolution, suitable for tomography, intermediate temperatures (25 or 42 K) may provide a modest improvement in cryo-protection without introducing deleterious effects evident at 4 K.     

Ethanol addition as a strategy for start-up and acclimation of an AnSBBR for the treatment of landfill leachate

This study evaluated the ethanol addition as a strategy for start-up and acclimation of a pilot scale (1300 L) anaerobic sequencing batch biofilm reactor (AnSBBR) for the treatment of municipal landfill leachate with seasonal biodegradability variations. The treatment was carried out at ambient temperature (23.8 ± 2.1 °C) in the landfill area. In a first attempt, the leachate collected directly from landfill showed to be predominantly recalcitrant to anaerobic treatment and the acclimation was not possible. In a second attempt, adding ethanol to leachate, the reactor was successfully acclimated. After acclimation, without ethanol addition, the COD_Total influent ranged from 4970 to 13040 mg L^?1 and the removal efficiencies ranged from 12.1% to 70.7%. A final test was carried out increasing the ammonia and free-ammonia concentration from 2486 mgN L^?1 and 184 mgN L^?1 to 4519 mgN L^?1 and 634 mgN L^?1, respectively, with no expressive inhibition verified. The start-up strategy was found to be feasible, providing the acclimation of the biomass in the AnSBBR, and maintaining the biomass active even when the leachate was recalcitrant.     

Gastroprotective activity of Sterculia striata A. St. Hil. & Naudin (Malvaceae) in rodents

The Sterculia striata ethanolic extract (Ss-EtOH) inhibited gastric lesions induced by ethanol, HCl/ethanol, and ischemia/reperfusion, but not those induced by indomethacin, and did not alter the gastric secretion. Ss-EtOH restored the catalase activity and content of nonprotein sulfhydryl groups in the stomach of mice treated with ethanol. The gastroprotection induced by Ss-EtOH in the ethanol-induced gastric lesion model was abolished by N(G)-nitroL-arginine methyl ester (L-NAME) pretreatment, suggesting the involvement of nitric oxide and antioxidant compounds, but not prostaglandins, in this activity. Lupeol obtained from Ss-EtOH promoted gastroprotection as well as the extract at the same dose, and it must therefore contribute to the observed effects.