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1.
Environ Pollut ; 258: 113758, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31881510

RESUMO

Natural halloysite nanotubes (HNTs) with a hollow lumen are already applied in numerous fields and enter the environment in increasing quantities, which may have effects on animal and human health. However their in vivo toxicity in mammals is still largely unclear. The aim of this study is to assess acute oral toxicity of HNTs in the stomach of mice and recovery. Oral HNTs at low dose (5 mg HNTs/kg BW) for 30 days increased in daily food and water intake and promoted mouse growth with no obvious adverse effect on the stomach. The promotive effect on mouse growth disappeared after cessation of oral administration of the nanotubes. Oral HNTs for 30 days at high dose (50 mg HNTs/kg BW) induced Si and Al accumulation in the stomach, which caused oxidative stress, inflammation and iNOS-mediated damage in the organ. The damage in the stomach led to slight atrophic gastritis and reduced mouse growth. Oral HNTs-induced changes at high dose were not observed after a 30-days recovery period. The findings provided the evidence that oral HNTs-induced acute toxicity in the stomach was reversible. More importantly, this research showed that Al and Si were cleared out of the mice by hepatic excretion and renal excretion, respectively, during the recovery period. The results suggest that HNTs at low concentration in environments have no adverse effect on mice, while there are health risks to mice under severe contamination by HNTs.


Assuntos
Argila , Nanotubos/toxicidade , Óxido Nítrico Sintase Tipo II/metabolismo , Estômago/enzimologia , Administração Oral , Alumínio , Animais , Camundongos , Estresse Oxidativo , Silício , Estômago/efeitos dos fármacos , Testes de Toxicidade Aguda
2.
Biomed Pharmacother ; 120: 109427, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31648165

RESUMO

Gastric cancer is recognized as one of the most common cancer. In-depth research of gastric precancerous lesions (GPL) plays an important role in preventing the occurrence of gastric cancer. Meanwhile, traditional treatment provides a novel sight in the prevention of occurrence and development of gastric cancer. The current study was designed to assess the effects of therapy with Weipixiao (WPX) decoction on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced GPL rats and the underlying molecular mechanisms. After 10-weeks treatment, all rats were sacrificed. Histopathological changes of gastric tissue were assessed via hematoxylin-eosin (HE) and High-iron diamine-Alcian blue-Periodic acid-Schiff (HID-AB-PAS) staining. To be fully evidenced, RT-qPCR, Western blot and immunohistochemistry were used to detect the expressions of LDHA, CD147, HIF-1α, MCT4, PI3K, AKT, mTOR and miRNA-34a, which were crucial factors for evaluating GPL in the aspect of glycolysis pathogenesis. According to the results of HE and HID-AB-PAS staining, it could be confirmed that MNNG-induced GPL rats were obviously reversed by WPX decoction. Additionally, the increased gene levels of LDHA, CD147, MCT4, PI3K, AKT, mTOR and HIF-1α in model group were down-regulated by WPX decoction, while miRNA-34a expression was decreased and up-regulated by WPX decoction. The significantly increased protein levels of LDHA, CD147, MCT4, PI3K, AKT, mTOR and HIF-1α induced by MNNG were attenuated in rats treated with WPX decoction. In brief, the findings of this study imply that abnormal glycolysis in MNNG-induced GPL rats was relieved by WPX decoction via regulation of the expressions of LDHA, CD147, HIF-1α, MCT4, PI3K, AKT, mTOR and miRNA-34a.


Assuntos
Anticarcinógenos/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , Glicólise/efeitos dos fármacos , Metilnitronitrosoguanidina , Lesões Pré-Cancerosas/prevenção & controle , Neoplasias Gástricas/prevenção & controle , Estômago/efeitos dos fármacos , Animais , Citoproteção , Modelos Animais de Doenças , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Masculino , Lesões Pré-Cancerosas/induzido quimicamente , Lesões Pré-Cancerosas/enzimologia , Lesões Pré-Cancerosas/patologia , Ratos Sprague-Dawley , Transdução de Sinais , Estômago/enzimologia , Estômago/patologia , Neoplasias Gástricas/induzido quimicamente , Neoplasias Gástricas/enzimologia , Neoplasias Gástricas/patologia
3.
Fish Physiol Biochem ; 45(4): 1309-1320, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31089992

RESUMO

An experiment was carried out to assess the effect of replacing fishmeal with mopane worm meal in the diet of Clarias gariepinus. Juvenile C. gariepinus weighing 67.04 ± 3 g were stocked in 15 rectangular concrete tanks connected to a recirculating system. Five diets denoted D1, D2, D3, D4 and D5 were formulated to replace fishmeal with mopane worm meal at 0, 10, 20, 40 and 60%. Triplicate groups of C. gariepinus were randomly assigned to each diet at a stocking density of 100 fish per tank. The fish were fed to apparent satiation twice daily for 51 days. All growth performance indices declined with higher mopane worm inclusion levels. Specific growth rate (SGR) declined from 1.85%/day in the control diet to 1.43%/day in diet 5. Protein efficiency ratio (PER) also declined from 25.27% in the control diet to 19.30% in diet 5. Apparent digestibility coefficient (ADC) followed a similar pattern declining from 92.2% in the control diet to 87.1% in diet 5. Both amylase and protease activity in the stomach increased with higher mopane worm inclusion levels. Despite the increased enzyme activity in the stomach, SGR declined. The decline in SGR was attributed to high acid detergent fibre (ADF 58.4 g/kg) and chitin in the mopane worm diets. Lipase and chitinase did not show any discernible pattern with high mopane worm inclusion levels in the stomach. In the intestines, protease, lipase and chitinase did not show any discernible pattern with high mopane worm inclusion levels. Consequently, the relationship between SGR and all these enzymes was weak. However, amylase activity declined with higher mopane worm inclusion levels in the intestines, and this resulted in decreased SGR (r2 = 0.6722). The negative effects of mopane worm meal were further confirmed by the increase in liver degradation scores at high mopane worm inclusion levels. The liver degradation score increased from 1.12 in the control to 2.46 in diet 5.


Assuntos
Ração Animal , Peixes-Gato , Dieta/veterinária , Larva , Mariposas , Amilases/metabolismo , Animais , Peixes-Gato/anatomia & histologia , Peixes-Gato/crescimento & desenvolvimento , Peixes-Gato/metabolismo , Quitinases/metabolismo , Hepatócitos/patologia , Mucosa Intestinal/enzimologia , Lipase/metabolismo , Peptídeo Hidrolases/metabolismo , Estômago/enzimologia
4.
J Pharmacol Exp Ther ; 369(3): 318-327, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30894456

RESUMO

Tegoprazan, a novel potassium-competitive acid blocker (P-CAB), is a next-generation therapeutics developed for the treatment of acid-related gastrointestinal diseases such as gastroesophageal reflux disease (GERD) and peptic ulcers. In the present study, the in vitro and in vivo pharmacological properties of tegoprazan were compared with those of esomeprazole, a representative proton pump inhibitor. In vitro enzyme assays were performed using ion-leaky vesicles containing gastric H+/K+-ATPases isolated from pigs. The in vivo efficacies of tegoprazan were evaluated in rat models of GERD and peptic ulcer. Tegoprazan inhibited the activity of porcine H+/K+-ATPase with an IC50 value of 0.53 µM in a reversible manner, whereas esomeprazole showed weak and irreversible inhibition with an IC50 value of 42.52 µM. In a GERD model, tegoprazan showed dose-dependent efficacy in inhibiting esophageal injury and gastric acid secretion with an ED50 of 2.0 mg/kg, which was 15-fold more potent than that of esomeprazole. In peptic ulcer models, tegoprazan exhibited superior antiulcer activity compared with esomeprazole. The ED50 of tegoprazan in the naproxen-, ethanol-, and water-immersion restraint stress-induced peptic ulcer models were 0.1, 1.4, and 0.1 mg/kg, respectively. In the acetic acid-induced peptic ulcer model, the curative ratio of tegoprazan at 10 mg/kg was higher than that of esomeprazole at 30 mg/kg (44.2% vs. 32.7%, respectively), after 5 days of repeated oral administration. Thus, tegoprazan is a novel P-CAB that shows potent and reversible inhibition of gastric H+/K+-ATPase and may provide stronger efficacy compared with previous proton pump inhibitors.


Assuntos
Derivados de Benzeno/farmacologia , Ácido Gástrico/metabolismo , Refluxo Gastroesofágico/tratamento farmacológico , Refluxo Gastroesofágico/metabolismo , Imidazóis/farmacologia , Úlcera Péptica/tratamento farmacológico , Úlcera Péptica/metabolismo , Potássio/metabolismo , Animais , Derivados de Benzeno/uso terapêutico , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Esomeprazol/farmacologia , ATPase Trocadora de Hidrogênio-Potássio/metabolismo , Imidazóis/uso terapêutico , Ratos , Estômago/efeitos dos fármacos , Estômago/enzimologia , Distribuição Tecidual
5.
Nat Protoc ; 14(4): 991-1014, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30886367

RESUMO

Developing a mechanistic understanding of the impact of food structure and composition on human health has increasingly involved simulating digestion in the upper gastrointestinal tract. These simulations have used a wide range of different conditions that often have very little physiological relevance, and this impedes the meaningful comparison of results. The standardized protocol presented here is based on an international consensus developed by the COST INFOGEST network. The method is designed to be used with standard laboratory equipment and requires limited experience to encourage a wide range of researchers to adopt it. It is a static digestion method that uses constant ratios of meal to digestive fluids and a constant pH for each step of digestion. This makes the method simple to use but not suitable for simulating digestion kinetics. Using this method, food samples are subjected to sequential oral, gastric and intestinal digestion while parameters such as electrolytes, enzymes, bile, dilution, pH and time of digestion are based on available physiological data. This amended and improved digestion method (INFOGEST 2.0) avoids challenges associated with the original method, such as the inclusion of the oral phase and the use of gastric lipase. The method can be used to assess the endpoints resulting from digestion of foods by analyzing the digestion products (e.g., peptides/amino acids, fatty acids, simple sugars) and evaluating the release of micronutrients from the food matrix. The whole protocol can be completed in ~7 d, including ~5 d required for the determination of enzyme activities.


Assuntos
Materiais Biomiméticos/metabolismo , Ingredientes de Alimentos/análise , Intestinos/enzimologia , Modelos Biológicos , Boca/enzimologia , Estômago/enzimologia , Aminoácidos/análise , Aminoácidos/química , Bile/enzimologia , Materiais Biomiméticos/química , Digestão/fisiologia , Ingestão de Alimentos/fisiologia , Ensaios Enzimáticos/normas , Ácidos Graxos/análise , Ácidos Graxos/química , Alimentos , Suco Gástrico/enzimologia , Humanos , Concentração de Íons de Hidrogênio , Hidrólise , Oligossacarídeos/análise , Oligossacarídeos/química , Fragmentos de Peptídeos/análise , Fragmentos de Peptídeos/química , Saliva/enzimologia
6.
Sci Rep ; 9(1): 159, 2019 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-30655565

RESUMO

Chitin is a polymer of N-acetyl-D-glucosamine (GlcNAc) and a main constituent of insects' exoskeleton. Insects are rich in protein with high energy conversion efficiency. Recently, we have reported that acidic chitinases (Chia) act as digestive enzymes in mouse, pig and chicken (omnivorous) but not in dog (carnivorous) and bovine (herbivorous), indicating that feeding behavior affects Chia expression levels, and determines chitin digestibility in the particular animals. Common marmoset (Callithrix jacchus) belongs to New World monkey family and provides a potential bridge between mouse models and human diseases. Common marmoset is an insectivorous nonhuman primate with unknown expression levels and enzymatic functions of the Chia homologue, CHIA. Here, we report that common marmoset highly expresses pepsin-, trypsin- and chymotrypsin-resistant CHIA in the stomach. We show that CHIA is most active at pH 2.0 and degrades chitin and mealworm shells into GlcNAc dimers under gastrointestinal conditions. Although common marmoset and crab-eating monkey (Old World monkey) have two CHIA genes in their genomes, they primarily express one gene in the stomach. Thus, this study is the first to investigate expression levels and enzymatic functions of CHIA in a New World primate, contributing to the understanding of dietary adaptation and digestion in this taxon.


Assuntos
Callithrix/metabolismo , Quitina/metabolismo , Quitinases , Estômago/enzimologia , Animais , Quitinases/química , Quitinases/metabolismo , Dieta , Comportamento Alimentar/psicologia
7.
Food Funct ; 10(1): 469-478, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30632597

RESUMO

The identification and isolation of bioactive compounds are of great interest in the drug delivery field, despite being a difficult task. We describe here an innovative strategy for the identification of a new gastric lipase inhibitor from star anise for the treatment of obesity. After plant screening assays for gastric lipase inhibition, star anise was selected and investigated by bioactivity guided fractionation. MALDI-TOF mass spectrometry and peptide mass fingerprinting allowed the detection of an inhibitor covalently bound to the catalytic serine of gastric lipase. A mass-directed screening approach using UPLC-HRMS and accurate mass determination searching identified the flavonoid myricitrin-5-methyl ether (M5ME) as a lipase inhibitor. The inhibitory activity was rationalized based on molecular docking, showing that M5ME is susceptible to nucleophilic attack by gastric lipase. Overall, our data suggest that M5ME may be considered as a potential candidate for future application as a gastric lipase inhibitor for the treatment of obesity.


Assuntos
Inibidores Enzimáticos/química , Illicium/química , Lipase/química , Extratos Vegetais/química , Estômago/enzimologia , Sítios de Ligação , Inibidores Enzimáticos/isolamento & purificação , Cinética , Espectrometria de Massas , Simulação de Acoplamento Molecular , Extratos Vegetais/isolamento & purificação
8.
J Gastrointestin Liver Dis ; 27(4): 371-378, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30574618

RESUMO

BACKGROUND AND AIMS: The increased oxidative stress plays an important role in gastro-duodenal ulcers and gastric cancer occurrence. We investigated the association between the genetic polymorphisms of genes encoding the antioxidative enzymes CAT, GPX and SOD and the occurrence of gastric lesions, considering also the environmental risk factors such as H. pylori infection, drug exposure, smoking and alcohol consumption. METHODS: We included 373 patients who underwent endoscopy for symptoms, anemia or bleeding investigation. A complete set of demographical, clinical and pathological data was recorded. All patients were successfully genotyped. RESULTS: In the multivariate logistic regression model, the patients having Pro/Pro genotype of GPX1 gene polymorphism had more severe gastric lesions as compared with patients with the Leu/Pro or Leu/Leu genotype (OR= 1.89, 95%CI: 0.99-3.57, p=0.051). The GPX1 Pro198Leu and the MnSOD Ala16Val gene polymorphism could be independent risk factors for reactive gastropathy changes, as shown by their association very close to statistical significance (p=0.059 and p=0.054, respectively). Consumption of anticoagulants was a significant independent predictor (p=0.023, OR:0.43 95%CI:0.21-0.89) for the absence of active gastritis, while low-dose aspirin consumption was a risk factor for active gastritis in biopsy samples (p=0.025, OR:1.71, 95%CI:1.07-2.74). CONCLUSION: The variant genotype of GPX1Pro198Leu was associated with an increased risk for reactive gastropathy changes in gastric biopsies and with less severe endoscopic lesions, while MnSODAla16Val variant genotype (Val/Val or Val/Ala) seems to be related to the reactive gastropathy. However, none of them were associated with inflammatory or premalignant gastric lesions.


Assuntos
Catalase/genética , Glutationa Peroxidase/genética , Estresse Oxidativo/genética , Polimorfismo Genético , Gastropatias/genética , Estômago/enzimologia , Superóxido Dismutase/genética , Idoso , Consumo de Bebidas Alcoólicas/efeitos adversos , Biópsia , Feminino , Gastroscopia , Estudos de Associação Genética , Predisposição Genética para Doença , Infecções por Helicobacter/diagnóstico , Infecções por Helicobacter/microbiologia , Helicobacter pylori/isolamento & purificação , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Fatores de Risco , Fumar/efeitos adversos , Estômago/microbiologia , Estômago/patologia , Gastropatias/diagnóstico , Gastropatias/enzimologia , Gastropatias/microbiologia
9.
Chem Pharm Bull (Tokyo) ; 66(9): 896-900, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30175749

RESUMO

To investigate the inhibitory effect of a commercial proton pump inhibitor (lansoprazole) on the gastric proton pump H+,K+-ATPase in vitro, we used orally disintegrating (OD) tablets including original brand-name and generic tablets. In the course of the development of generic products, dissolution and clinical tests are necessary to ensure their bioequivalence to the original brand-name products; by contrast, there is almost no opportunity to demonstrate their activity in vitro. This study initially compared the similarity of the dissolution of test generic tablets with that of the original brand-name tablets. The dissolution tests for 15 and 30-mg lansoprazole tablets found their dissolution properties were similar. Subsequently, the dissolution media were sampled and then their effects on the H+,K+-ATPase activity were measured using tubulovesicles prepared from the gastric mucosa of hogs. We confirmed that the inhibitory effects of the generic tablets on H+,K+-ATPase activity were consistent with those of the original brand-name tablets. Furthermore, lansoprazole contents in each tablet estimated from their inhibitory effects were in good agreement with their active pharmaceutical ingredient content. To our knowledge, this is the first technical report to compare the in vitro biochemical activity of lansoprazole OD tablets between the original brand-name and generic commercial products.


Assuntos
Adenosina Trifosfatases/antagonistas & inibidores , Lansoprazol/farmacologia , Inibidores da Bomba de Prótons/farmacologia , Adenosina Trifosfatases/metabolismo , Administração Oral , Animais , Medicamentos Genéricos , Humanos , Lansoprazol/química , Inibidores da Bomba de Prótons/química , Solubilidade , Estômago/citologia , Estômago/enzimologia , Suínos , Comprimidos , Equivalência Terapêutica
10.
Fish Shellfish Immunol ; 80: 191-199, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29803665

RESUMO

Aquatic animals are frequently suffered from starvation due to restricted food availability or deprivation. It is currently known that gut microbiota assists host in nutrient acquisition. Thus, exploring the gut microbiota responses would improve our understanding on physiological adaptation to starvation. To achieve this, we investigated how the gut microbiota and shrimp digestion and immune activities were affected under starvation stress. The results showed that the measured digestion activities in starved shrimp were significantly lower than in normal cohorts; while the measured immune activities exhibited an opposite trend. A structural equation modeling (SEM) revealed that changes in the gut bacterial community were directly related to digestive and immune enzyme activities, which in turn markedly affected shrimp growth traits. Notably, several gut bacterial indicators that characterized the shrimp nutrient status were identified, with more abundant opportunistic pathogens in starved shrimp, although there were no statistical differences in the overall diversity and the structures of gut bacterial communities between starved and normal shrimp. Starved shrimp exhibited less connected and cooperative interspecies interaction as compared with normal cohorts. Additionally, the functional pathways involved in carbohydrate and protein digestion, glycan biosynthesis, lipid and enzyme metabolism remarkably decreased in starved shrimp. These attenuations could increase the susceptibility of starved shrimp to pathogens infection. In summary, this study provides novel insights into the interplay among shrimp digestion, immune activities and gut microbiota in response to starvation stress.


Assuntos
Digestão , Microbioma Gastrointestinal , Penaeidae , Inanição , Estresse Fisiológico , Fosfatase Ácida/metabolismo , Amilases/metabolismo , Animais , Bactérias/genética , Digestão/imunologia , Digestão/fisiologia , Hepatopâncreas/enzimologia , Lipase/metabolismo , Muramidase/metabolismo , Penaeidae/imunologia , Penaeidae/microbiologia , Penaeidae/fisiologia , Pepsina A/metabolismo , RNA Ribossômico 16S/genética , Inanição/imunologia , Inanição/microbiologia , Estômago/enzimologia , Estresse Fisiológico/imunologia , Estresse Fisiológico/fisiologia , Superóxido Dismutase/metabolismo
11.
ACS Chem Neurosci ; 9(7): 1663-1679, 2018 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-29697965

RESUMO

Alzheimer's disease (AD) is associated with multiple neuropathological events including ß-site amyloid precursor protein cleaving enzyme-1 (BACE-1) inhibition and neuronal inflammation, ensuing degeneracy, and death to neuronal cells. Targeting such a complex disease via a single target directed treatment was found to be inefficacious. Hence, with an intention to incorporate multiple therapeutic effects within a single molecule, multitarget-directed ligands (MTDLs) have been evolved. Herein, for the first time, we report the discovery of novel thiazolyl-thiadiazines that can serve as MTDLs as evident from the in vitro and in vivo studies. These MTDLs exhibited BACE-1 inhibition down to micromolar range, and results from the in vivo studies demonstrated efficient anti-inflammatory activity with inherent gastrointestinal safety. Moreover, compound 6d unveiled noteworthy antioxidant, antiamyloid, neuroprotective, and antiamnesic properties. Overall, results of the present study manifest the potential outcome of thiazolyl-thiadiazines for AD treatment.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Anti-Inflamatórios não Esteroides/farmacologia , Tiadiazinas/farmacologia , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/enzimologia , Doença de Alzheimer/patologia , Animais , Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/química , Antioxidantes/síntese química , Antioxidantes/química , Antioxidantes/farmacologia , Encéfalo/efeitos dos fármacos , Encéfalo/enzimologia , Encéfalo/patologia , Modelos Animais de Doenças , Desenho de Fármacos , Inflamação/tratamento farmacológico , Inflamação/enzimologia , Inflamação/patologia , Intestinos/efeitos dos fármacos , Intestinos/enzimologia , Intestinos/patologia , Simulação de Acoplamento Molecular , Estrutura Molecular , Ratos Sprague-Dawley , Estômago/efeitos dos fármacos , Estômago/enzimologia , Estômago/patologia , Tiadiazinas/síntese química , Tiadiazinas/química
12.
Nature ; 556(7700): 214-218, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29618813

RESUMO

The gastric proton pump-the H+, K+-ATPase-is a P-type ATPase responsible for acidifying the gastric juice down to pH 1. This corresponds to a million-fold proton gradient across the membrane of the parietal cell, the steepest known cation gradient of any mammalian tissue. The H+, K+-ATPase is an important target for drugs that treat gastric acid-related diseases. Here we present crystal structures of the H+, K+-ATPase in complex with two blockers, vonoprazan and SCH28080, in the luminal-open state, at 2.8 Å resolution. The drugs have partially overlapping but clearly distinct binding modes in the middle of a conduit running from the gastric lumen to the cation-binding site. The crystal structures suggest that the tight configuration at the cation-binding site lowers the pK a value of Glu820 sufficiently to enable the release of a proton even into the pH 1 environment of the stomach.


Assuntos
ATPase Trocadora de Hidrogênio-Potássio/química , Estômago/enzimologia , Sequência de Aminoácidos , Animais , Sítios de Ligação , Cátions Monovalentes/metabolismo , Cristalografia por Raios X , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Imidazóis/química , Imidazóis/farmacologia , Modelos Moleculares , Potássio/metabolismo , Ligação Proteica , Inibidores da Bomba de Prótons/química , Inibidores da Bomba de Prótons/farmacologia , Prótons , Pirróis/química , Pirróis/farmacologia , Coelhos , Sulfonamidas/química , Sulfonamidas/farmacologia , Suínos
13.
Sci Rep ; 8(1): 1461, 2018 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-29362395

RESUMO

Chitin, a polymer of N-acetyl-D-glucosamine (GlcNAc), functions as a major structural component in chitin-containing organism including crustaceans, insects and fungi. Recently, we reported that acidic chitinase (Chia) is highly expressed in mouse, chicken and pig stomach tissues and that it can digest chitin in the respective gastrointestinal tracts (GIT). In this study, we focus on major livestock and domestic animals and show that the levels of Chia mRNA in their stomach tissues are governed by the feeding behavior. Chia mRNA levels were significantly lower in the bovine (herbivores) and dog (carnivores) stomach than those in mouse, pig and chicken (omnivores). Consistent with the mRNA levels, Chia protein was very low in bovine stomach. In addition, the chitinolytic activity of E. coli-expressed bovine and dog Chia enzymes were moderately but significantly lower compared with those of the omnivorous Chia enzymes. Recombinant bovine and dog Chia enzymes can degrade chitin substrates under the artificial GIT conditions. Furthermore, genomes of some herbivorous animals such as rabbit and guinea pig do not contain functional Chia genes. These results indicate that feeding behavior affects Chia expression levels as well as chitinolytic activity of the enzyme, and determines chitin digestibility in the particular animals.


Assuntos
Quitina/química , Quitinases/genética , Quitinases/metabolismo , Estômago/enzimologia , Animais , Bovinos , Galinhas , Cães , Comportamento Alimentar , Regulação da Expressão Gênica , Cobaias , RNA Mensageiro/genética , Especificidade da Espécie , Estômago/química
14.
Int J Mol Sci ; 19(2)2018 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-29370114

RESUMO

Acidic chitinase (Chia) has been implicated in asthma, allergic inflammations, and food processing. We have purified Chia enzymes with striking acid stability and protease resistance from chicken and pig stomach tissues using a chitin column and 8 M urea (urea-Chia). Here, we report that acetic acid is a suitable agent for native Chia purification from the stomach tissues using a chitin column (acetic acid-Chia). Chia protein can be eluted from a chitin column using 0.1 M acetic acid (pH 2.8), but not by using Gly-HCl (pH 2.5) or sodium acetate (pH 4.0 or 5.5). The melting temperatures of Chia are not affected substantially in the elution buffers, as assessed by differential scanning fluorimetry. Interestingly, acetic acid appears to be more effective for Chia-chitin dissociation than do other organic acids with similar structures. We propose a novel concept of this dissociation based on competitive interaction between chitin and acetic acid rather than on acid denaturation. Acetic acid-Chia also showed similar chitinolytic activity to urea-Chia, indicating that Chia is extremely stable against acid, proteases, and denaturing agents. Both acetic acid- and urea-Chia seem to have good potential for supplementation or compensatory purposes in agriculture or even biomedicine.


Assuntos
Quitina/química , Quitinases/química , Ácido Acético/química , Animais , Galinhas , Quitina/metabolismo , Quitinases/metabolismo , Ligação Proteica , Estômago/enzimologia , Suínos
15.
Food Funct ; 9(1): 200-208, 2018 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-29260815

RESUMO

The role of salivary α-amylase (HSA) in starch digestion is often overlooked in favour of that of pancreatic α-amylase due to the short duration of the oral phase. Although it is generally accepted that the amylase of salivary origin can continue to be active in the stomach, studies ascertaining its contribution are lacking. This study aimed to address this issue by coupling in vitro oral processing with an in vitro dynamic system that mimicked different postprandial gastric pH reduction kinetics observed in vivo following a snack- or lunch-type meal. The digestion of both starch and protein from wheat bread as well as the interplay between the two processes were studied. We have observed that the amylolytic activity of saliva plays a preponderant role hydrolysing up to 80% of bread starch in the first 30 min of gastric digestion. Amylolysis evolved exponentially and nearly superimposing curves were obtained regardless of the acidification profiles, revealing its high efficiency.


Assuntos
Amilases/metabolismo , Pão/análise , Saliva/enzimologia , Triticum/metabolismo , Amilases/química , Digestão , Mucosa Gástrica/metabolismo , Humanos , Cinética , Saliva/química , Saliva/metabolismo , Amido/metabolismo , Estômago/química , Estômago/enzimologia
16.
Eur J Pharmacol ; 820: 217-221, 2018 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-29274333

RESUMO

Myricetin (3,3',4',5,5',7-hexahydroxyflavone), a major flavonoid in berries and red wine, has been recently used as a health food supplement based on its antioxidant and antitumor properties. We report here that myricetin preferentially exerts inhibitory effects on gastric H+, K+-ATPase. Myricetin inhibited H+, K+-ATPase with a sub-micromolar IC50 value in an enzyme assay using freeze-dried tubulovesicles prepared from hog stomach. Na+, K+-ATPase and Ca2+-ATPase were also inhibited by myricetin in a dose-dependent manner, but the IC50 values for these enzymes were approximately an order of magnitude higher compared to the H+, K+-ATPase. In structure-inhibitory functional analysis of sixteen myricetin derivatives, several phenolic hydroxy groups attached to the flavonoid backbone were highlighted as essential modifications for the inhibition of P2-type ATPases. Furthermore, oral administration of myricetin significantly attenuated histamine-induced gastric acid secretion in an in vivo mouse assessment. Therefore, myricetin derivatives seem to be useful seed compounds for developing new drugs and supplements to alleviate gastric acid secretion.


Assuntos
Produtos Biológicos/farmacologia , Flavonoides/farmacologia , ATPase Trocadora de Hidrogênio-Potássio/metabolismo , Inibidores da Bomba de Prótons/farmacologia , Estômago/enzimologia , Animais , Produtos Biológicos/química , Cálcio/metabolismo , Flavonoides/química , Ácido Gástrico/metabolismo , Mucosa Gástrica/metabolismo , Inibidores da Bomba de Prótons/química , Bombas de Próton/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo
17.
J Fish Biol ; 92(1): 3-16, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29139124

RESUMO

The histochemical distribution of acid phosphatase (ACP), alkaline phosphatase (ALP), non-specific esterase (NSE), peroxidase (POD) and mucous-cell types was evaluated in the gastrointestinal tract of the half-smooth tongue sole Cynoglossus semilaevis. The enzymes were detected in the entire stretch of the gastrointestinal tract. ACP activity was found in the supranuclear region of enterocytes and the lamina propria of the intestine, as well as the cytoplasm of epithelial cells of the stomach. The staining intensity of ACP in the anterior and posterior intestines was stronger than in the stomach. ALP activity was detected in the striated border of enterocytes and muscularis of the whole intestine, lamina propria and supranuclear cytoplasm of the enterocytes in the anterior intestine, as well as in the blood vessels of the stomach. The staining intensity for ALP in the anterior intestine was stronger than in the posterior segment and the latter was stronger than in the stomach. NSE activity was detected in the cytoplasm of the epithelial cells in the entire gastrointestinal tract, with the anterior intestine showing stronger intensity than the stomach. POD activity was located in the blood cells of the lamina propria of the gastrointestinal tract and the levels in the stomach were similar to the anterior and posterior intestines. Alcian blue (pH 2·5) periodic acid Schiff (AB-PAS) histochemical results revealed three types of mucous cells in the gastrointestinal tract. Type I cells (PAS+AB-) were observed among the gastric mucosa columnar cells in the stomach and enterocytes in the basal region of the villi and in the middle and top regions of the intestinal villi. Type II cells (PAS-AB+) and type III cells (PAS+AB+) were not detected in the stomach but were distributed ubiquitously among enterocytes in the middle and top regions of the intestinal villi.


Assuntos
Linguados/metabolismo , Trato Gastrointestinal/enzimologia , Animais , Enterócitos/enzimologia , Células Epiteliais/enzimologia , Mucosa Intestinal/enzimologia , Estômago/enzimologia
18.
Dig Dis ; 36(2): 98-105, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-28982106

RESUMO

BACKGROUND: Functional dyspepsia is a heterogeneous disorder lacking an established therapeutic strategy. Historical treatment attempts with pepsin products were shrugged off, as a simple calculation shows that quantitative substitution is pointless. However, such attempts might have been right for the wrong reason. SUMMARY: Today, the role of pepsins is primarily seen in the provision of signalling amino acids (especially phenylalanine and tryptophan) and peptides, which initiate processes promoting digestion. Proteolysis benefits from pepsin variants showing, contrary to common belief, activities of up to a pH value of 5.0. Non-clinical and clinical studies support the view that liberated amino acids produce a variety of direct and indirect effects. Signal chains stimulated by (mostly aromatic) amino acids lead to secretion of gastrin and cholecystokinin (CCK), mediated, respectively, by CCK2 (gastrin) and Ca2+-sensing receptors in the parietal cell, and Ca2+-sensing receptors in the antral and duodenal mucosa. Thus, CCK effects such as secretion of pancreatic enzymes and promotion of gastric accommodation are (also) consequential to peptic liberation of amino acids. Key Message: As functional dyspepsia represents a heterogeneous disorder, it may be intriguing to view pepsin as a potential (although still to be proven) treatment modality, distinguished by a diversity of pro-digestive effects.


Assuntos
Dispepsia/enzimologia , Pepsina A/metabolismo , Aminoácidos/metabolismo , Animais , Digestão , Dispepsia/fisiopatologia , Humanos , Proteólise , Estômago/enzimologia
19.
Sci Rep ; 7(1): 13636, 2017 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-29057967

RESUMO

Helicobacter pylori γ-glutamyl transferase (gGT) is a key bacterial virulence factor that is not only important for bacterial gastric colonization but also related to the development of gastric pathology. Despite accumulating evidence for pathogenic and immunologic functions of H. pylori gGT, it is still unclear how it supports gastric colonization and how its specific effects on the host's innate and adaptive immune responses contribute to colonization and pathology. We have compared mice showing similar bacterial load after infection with gGT-proficient or gGT-deficient H. pylori to analyse the specific role of the enzyme during infection. Our data indicate that H. pylori gGT supports initial colonization. Nevertheless, bacteria lacking gGT can still colonize and persist. We observed that the presence of gGT during infection favoured a proinflammatory innate and adaptive immune response. Notably, H. pylori gGT activity was linked to increased levels of IFNγ, which were attributed to a differential recruitment of CD8+ T cells to the stomach. Our data support an essential role for H. pylori gGT in gastric colonization and further suggest that gGT favours infiltration of CD8+ cells to the gastric mucosa, which might play an important and yet overlooked role in the pathogenesis of H. pylori.


Assuntos
Proteínas de Bactérias/metabolismo , Linfócitos T CD8-Positivos/imunologia , Infecções por Helicobacter/imunologia , Helicobacter pylori/enzimologia , Fatores de Virulência/metabolismo , gama-Glutamiltransferase/metabolismo , Imunidade Adaptativa , Animais , Linfócitos T CD8-Positivos/enzimologia , Linfócitos T CD8-Positivos/microbiologia , Modelos Animais de Doenças , Feminino , Infecções por Helicobacter/enzimologia , Infecções por Helicobacter/microbiologia , Infecções por Helicobacter/patologia , Helicobacter pylori/crescimento & desenvolvimento , Imunidade Inata , Interferon gama/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Estômago/enzimologia , Estômago/imunologia , Estômago/microbiologia , Estômago/patologia
20.
Food Funct ; 8(9): 3339-3345, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-28849829

RESUMO

Kiwifruit contains the cysteine proteinase actinidin whose strong activity allows kiwifruit to be used as a meat tenderiser. This raises the possibility digestive enzymes, also proteins, are themselves susceptible to degradation by actinidin. Salivary amylase and gastric lipase are exposed to the highest concentrations of actinidin whereas duodenal enzymes are less likely to be inactivated by actinidin due to dilution and inactivation of actinidin by gastric juice. The saliva of six volunteers was exposed to Actinidia deliciosa homogenate and then examined for loss of the starch digesting enzyme, alpha-amylase. In agreement with the known distribution of salivary amylase concentration in saliva, the range of amylase activity within the group of volunteers varied by around 100 fold. Within 5 minutes of incubation of 3 parts saliva to one part green kiwifruit at 37 °C, approximately 85% of the amylase activity was lost. The use of E-64, a selective inhibitor of cysteine proteinases, confirmed that the loss of amylase function was due to actinidin. Amylase protein degradation was followed by SDS-PAGE and western blotting. Recombinant human gastric lipase resisted digestion with kiwifruit even after 30 minutes incubation and remained functionally active after this time period. However, both mountain papaya and pineapple extracts degraded gastric lipase fully during a 30 minutes digestion period. Under conditions where cooked starch is consumed along with kiwifruit it is possible that starch digestion may be retarded whereas lipid digestion in the stomach is unlikely to be affected by kiwifruit consumption.


Assuntos
Actinidia/enzimologia , Cisteína Endopeptidases/química , Lipase/química , Saliva/enzimologia , Estômago/enzimologia , alfa-Amilases/química , Actinidia/química , Adulto , Idoso , Biocatálise , Digestão , Feminino , Frutas/química , Frutas/enzimologia , Humanos , Masculino , Pessoa de Meia-Idade , Saliva/química , Estômago/química
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