Investigation of Intestinal Absorption and Excretion of Paracetamol in Streptozotocin-Induced Hyperglycemia.

The phenolic drug molecules can be metabolized, among others, by the small intestine's enterocytes. The conjugation reactions (glucuronidation and sulfation) show great importance in these transformations, although the oxidation reactions can be significant. These processes are dependent on the substituents of the phenolic compounds or the reacting functional groups (hydroxyl or carboxyl). Pathologic conditions, e.g., permanent hyperglycemia and diabetes, can alter the activities of the conjugative and possibly the oxidative enzymes, thus forming a change in the metabolic pattern and eventually provoking oxidative stress. A rat intestinal perfusion model was used to investigate the way in which experimental hyperglycemia affects the paracetamol's intestinal elimination and metabolism. Hyperglycemia was induced by the administration of streptozotocin. Two hundred and fifty µM paracetamol was used in the intestinal perfusion solution. For the quantitation of the paracetamol and its major metabolites in the intestinal perfusate, an isocratic high-performance liquid chromatography method with UV-Vis detection was developed. The results revealed that quantities of all of the measured metabolites (glucuronide, sulfate, cysteine, and mercapturic acid conjugates) increased as the effect of the streptozotocin-induced hyperglycemia also did. In the small intestine's homogenate, the glutathione levels showed that there was a decrease in the hyperglycemia levels after the paracetamol administration. In contrast, the tissue levels of the cysteine were lower in the streptozotocin-induced hyperglycemia and increased after the administration of the paracetamol. The changes in the activity of the intestinal CYP 3A4, CYP 2E1, and cyclooxygenase (COX) enzymes were determined in the control and the hyperglycemic cases. Still, there was a significant observable enzyme activity elevation in the intestinal COX enzymes, but there was a decrease in the amount of activity of the intestinal CYP3A4 enzymes, and the CYP2E1 enzyme activity was practically changeless. The results on the cysteine levels in the intestinal homogenate, at least partly, can be explained by the regulation function of the cysteine during the occurrence of oxidative stress.

The Intestinal and Biliary Metabolites of Ibuprofen in the Rat with Experimental Hyperglycemia.

Hyperglycemia is reported to be associated with oxidative stress. It can result in changes in the activities of drug-metabolizing enzymes and membrane-integrated transporters, which can modify the fate of drugs and other xenobiotics; furthermore, it can result in the formation of non-enzyme catalyzed oxidative metabolites. The present work aimed to investigate how experimental hyperglycemia affects the intestinal and biliary appearance of the oxidative and Phase II metabolites of ibuprofen in rats. In vivo studies were performed by luminal perfusion of 250 µM racemic ibuprofen solution in control and streptozotocin-treated (hyperglycemic) rats. Analysis of the collected intestinal perfusate and bile samples was performed by HPLC-UV and HPLC-MS. No oxidative metabolites could be detected in the perfusate samples. The biliary appearance of ibuprofen, 2-hydroxyibuprofen, ibuprofen glucuronide, hydroxylated ibuprofen glucuronide, and ibuprofen taurate was depressed in the hyperglycemic animals. However, no specific non-enzymatic (hydroxyl radical initiated) hydroxylation product could be detected. Instead, the depression of biliary excretion of ibuprofen and ibuprofen metabolites turned out to be the indicative marker of hyperglycemia. The observed changes impact the pharmacokinetics of drugs administered in hyperglycemic individuals.

Investigation of intestinal elimination and biliary excretion of ibuprofen in hyperglycemic rats.

An in vivo intestinal perfusion model was used to investigate how experimental hyperglycemia affects intestinal elimination and biliary excretion in the rat. Experimental diabetes was induced by administration of streptozotocin (65 mg/kg, i.v.). The intestinal perfusion medium contained 250 µM (±)-ibuprofen. An isocratic high-performance liquid chromatography method with UV-visible detection was developed to quantitate ibuprofen in the intestinal perfusate, while a gradient method was applied to quantitate ibuprofen and ibuprofen-ß-d-glucuronide in the bile. The limit of quantitation of ibuprofen was found to be 0.51 µM in the perfusate of the small intestine. In the bile, the limit of quantitation of ibuprofen and ibuprofen-ß-d-glucuronide was 4.42 and 10.3 µM, respectively. Unconjugated ibuprofen and ibuprofen-ß-d-glucuronide were detected in the bile; however, no ß-d-glucuronide of ibuprofen could be detected in the intestinal perfusate. The results indicate that experimental diabetes can cause a decrease in the disappearance of ibuprofen from the small intestine. Excretion of both ibuprofen and ibuprofen-ß-d-glucuronide decreased to the bile in experimental diabetes. The results can be explained by the results of molecular biological studies indicating streptozotocin-initiated alterations in the intestinal and hepatic transport processes.

Toxicokinetic Study of a Gastroprotective Dose of Capsaicin by HPLC-FLD Method.

BACKGROUND: A low dose of capsaicin and its natural homologs and analogs (capsaicinoids) have shown to prevent development of gastric mucosal damage of alcohol and non-steroid anti-inflammatory drugs. Based on this experimental observation, a drug development program has been initiated to develop per os applicable capsaicin containing drugs to eliminate gastrointestinal damage caused by non-steroid anti-inflammatory drugs. METHODS: As a part of this program, a sensitive and selective reverse-phase high-performance liquid chromatography-based method with fluorescence detection has been developed for quantification of capsaicin and dihydrocapsaicin in experimental dog's plasma. RESULTS: The method was evaluated for a number of validation characteristics (selectivity, repeatability, and intermediate precision, LOD, LOQ, and calibration range). The limit of detection (LOD) was 2 ng/mL and the limit of quantification (LOQ) was 10 ng/mL for both capsaicin and dihydrocapsaicin. The method was used for analysis of capsaicin and dihydrocapsaicin in the plasma samples obtained after per os administration of low doses (0.1, 0.3, and 0.9 mg/kg bw) of Capsaicin Natural (USP 29) to the experimental animals. CONCLUSIONS: The obtained results indicated that the administered capsaicinoids did not reach the general circulation.

Effect of experimental diabetes and insulin replacement on intestinal metabolism and excretion of 4-nitrophenol in rats.

Luminal appearance of 4-nitrophenol (PNP) metabolites (4-nitrophenol-ß-glucuronide (PNP-G) and 4-nitrophenol-sulfate (PNP-S)) and activity of the related metabolic enzymes have been investigated in control and experimental diabetic rats. Experimental diabetes was induced by administration of streptozotocin (65 mg/kg i.v.). PNP (500 µmol/L) was luminally perfused in the small intestine and the metabolites were determined in the perfusion solution. Effect of insulin replacement was also investigated in the diabetic rats. It was found that experimental diabetes increased the luminal appearance of PNP-G, which could be completely compensated by rapid-acting insulin administration (1 U/kg i.v.). Activities of the enzymes involved in PNP-G production (UDP-glucuronyltransferase and ß-glucuronidase) were also elevated; however, these changes were only partially compensated by insulin. Luminal appearance of PNP-S was not significantly changed by administration of streptozotocin and insulin. Activities of the enzymes of PNP-S production (sulfotransferases and arylsulfatases) did not change in the diabetic rats. The results indicate that experimental diabetes can provoke changes in intestinal drug metabolism. It increased intestinal glucuronidation of PNP but did not influence sulfate conjugation. No direct correlation was found between the changes of metabolic enzyme activities and the luminal appearance of the metabolites.

Alterations of the expression levels of glucose, inflammation, and iron metabolism related miRNAs and their target genes in the hypothalamus of STZ-induced rat diabetes model.

BACKGROUND: The hypothalamus of the central nervous system is implicated in the development of diabetes due to its glucose-sensing function. Dysregulation of the hypothalamic glucose-sensing neurons leads to abnormal glucose metabolism. It has been described that fractalkine (FKN) is involved in the development of hypothalamic inflammation, which may be one of the underlying causes of a diabetic condition. Moreover, iron may play a role in the pathogenesis of diabetes via the regulation of hepcidin, the iron regulatory hormone synthesis. MicroRNAs (miRNAs) are short non-coding molecules working as key regulators of gene expression, usually by inhibiting translation. Hypothalamic miRNAs are supposed to have a role in the control of energy balance by acting as regulators of hypothalamic glucose metabolism via influencing translation. METHODS: Using a miRNA array, we analysed the expression of diabetes, inflammation, and iron metabolism related miRNAs in the hypothalamus of a streptozotocin-induced rat type 1 diabetes model. Determination of the effect of miRNAs altered by STZ treatment on the target genes was carried out at protein level. RESULTS: We found 18 miRNAs with altered expression levels in the hypothalamus of the STZ-treated animals, which act as the regulators of mRNAs involved in glucose metabolism, pro-inflammatory cytokine synthesis, and iron homeostasis suggesting a link between these processes in diabetes. The alterations in the expression level of these miRNAs could modify hypothalamic glucose sensing, tolerance, uptake, and phosphorylation by affecting the stability of hexokinase-2, insulin receptor, leptin receptor, glucokinase, GLUT4, insulin-like growth factor receptor 1, and phosphoenolpyruvate carboxykinase mRNA molecules. Additional miRNAs were found to be altered resulting in the elevation of FKN protein. The miRNA, mRNA, and protein analyses of the diabetic hypothalamus revealed that the iron import, export, and iron storage were all influenced by miRNAs suggesting the disturbance of hypothalamic iron homeostasis. CONCLUSION: It can be supposed that glucose metabolism, inflammation, and iron homeostasis of the hypothalamus are linked via the altered expression of common miRNAs as well as the increased expression of FKN, which contribute to the imbalance of energy homeostasis, the synthesis of pro-inflammatory cytokines, and the iron accumulation of the hypothalamus. The results raise the possibility that FKN could be a potential target of new therapies targeting both inflammation and iron disturbances in diabetic conditions.

Effect of Bitis gabonica and Dendroaspis angusticeps snake venoms on apoptosis-related genes in human thymic epithelial cells.

BACKGROUND: Certain environmental toxins permanently damage the thymic epithelium, accelerate immune senescence and trigger secondary immune pathologies. However, the exact underlying cellular mechanisms and pathways of permanent immune intoxication remain unknown. The aim of the present study was to demonstrate gene expressional changes of apoptosis-related cellular pathways in human thymic epithelial cells following exposure to snake venom from Bitis gabonica and Dendroaspis angusticeps. METHODS: Snake venoms were characterized by analytical methods including reversed phase high-performance liquid chromatography and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, then applied on human thymic epithelial cells (1889c) for 24 h at 10 µg/mL (as used in previous TaqMan Array study). Gene expressional changes restricted to apoptosis were assayed by TaqMan Array (Human Apoptosis Plate). RESULTS: The most prominent gene expressional changes were shown by CASP5 (≈ 2.5 million-fold, confirmed by dedicated quantitative polymerase chain reaction) and CARD9 (0.016-fold) for B. gabonica, and BIRC7 (6.46-fold) and CASP1 (0.30-fold) for D. angusticeps. CONCLUSION: The observed apoptotic environment suggests that pyroptosis may be the dominant pathway through which B. gabonica and D. angusticeps snake venoms trigger thymic epithelial apoptosis following envenomation.

Semi-automated construction of decision rules to predict morbidities from clinical texts.

OBJECTIVE In this study the authors describe the system submitted by the team of University of Szeged to the second i2b2 Challenge in Natural Language Processing for Clinical Data. The challenge focused on the development of automatic systems that analyzed clinical discharge summary texts and addressed the following question: "Who's obese and what co-morbidities do they (definitely/most likely) have?". Target diseases included obesity and its 15 most frequent comorbidities exhibited by patients, while the target labels corresponded to expert judgments based on textual evidence and intuition (separately). DESIGN The authors applied statistical methods to preselect the most common and confident terms and evaluated outlier documents by hand to discover infrequent spelling variants. The authors expected a system with dictionaries gathered semi-automatically to have a good performance with moderate development costs (the authors examined just a small proportion of the records manually). MEASUREMENTS Following the standard evaluation method of the second Workshop on challenges in Natural Language Processing for Clinical Data, the authors used both macro- and microaveraged Fbeta=1 measure for evaluation. RESULTS The authors submission achieved a microaverage F(beta=1) score of 97.29% for classification based on textual evidence (macroaverage F(beta=1) = 76.22%) and 96.42% for intuitive judgments (macroaverage F(beta=1) = 67.27%). CONCLUSIONS The results demonstrate the feasibility of the authors approach and show that even very simple systems with a shallow linguistic analysis can achieve remarkable accuracy scores for classifying clinical records on a limited set of concepts.

HPLC study on Fenton-reaction initiated oxidation of salicylic acid. Biological relevance of the reaction in intestinal biotransformation of salicylic acid.

Fenton-reaction initiated in vitro oxidation and in vivo oxidative biotransformation of salicylic acid was investigated by HPLC-UV-Vis method. By means of the developed high performance liquid chromatography (HPLC) method salicylic acid, catechol, and all the possible monohydroxylated derivatives of salicylic acid can be separated. Fenton oxidations were performed in acidic medium (pH 3.0) with two reagent molar ratios: (1) salicylic acid: iron: hydrogen peroxide 1:3:1 and (2) 1:0.3:1. The incubation samples were analysed at different time points of the reactions. The biological effect of elevated reactive oxygen species concentration on the intestinal metabolism of salicylic acid was investigated by an experimental diabetic rat model. HPLC-MS analysis of the in vitro samples revealed presence of 2,3- and 2,5-dihydroxybenzoic acids. The results give evidence for nonenzyme catalysed intestinal hydroxylation of xenobiotics.

Effects of Mesalazine on Morphological and Functional Changes in the Indomethacin-Induced Inflammatory Bowel Disease (Rat Model of Crohn's Disease).

Morphological and functional changes have been investigated in the rat model of Crohn's disease. The inflammatory bowel disease was induced by indomethacin (1 × 10 mg/kg s.c. for 3 days). Morphological alterations were evaluated by macroscopic scoring system and on the base of histological changes in the small intestine. Functional activities were studied by determination of the intestinal and hepatic elimination of p-Nitrophenol (PNP) and its metabolites (PNP-glucuronide: PNP-G and PNP-sulfate: PNP-S) during the luminal perfusion of PNP. It was found that the indomethacin induced severe macroscopic changes (hyperaemia, petechia, bleeding, erosions, ulcerations) and significant histological alterations in the small intestine of rats which were definitely inhibited by mesalazine (1000 mg/kg by gastric tube for 3 days). Disappearance of PNP from the luminal perfusion solution was diminished by indomethacin which was corrected by administration of mesalazine. Significant depression was found in the luminal appearance of PNP metabolites by giving of indomethacin and these alterations could not be compensated by mesalazine.Hepatic elimination of PNP (biliary excretion of PNP and its metabolites) was decreased definitely by indomethacin which was - at least partly - compensated by mesalazine.The findings of the present study suggest that the indomethacin-induced inflammation in the small intestine represents a useful rat model of Crohn's disease. Morphological and functional alterations caused by indomethacin can be compensated by mesalazine.

A simple and rapid ion-pair HPLC method for simultaneous quantitation of 4-nitrophenol and its glucuronide and sulfate conjugates.

Because of its simple and well characterized metabolic profile, 4-nitrophenol is widely used as a model substrate to investigate the influence of drug therapy, disease, nutrient deficiencies and other physiologically altered conditions on conjugative drug metabolism in animal studies. For simultaneous determination of 4-nitrophenol (PNP), 4-nitrophenyl-beta-D-glucuronide (PNP-G) and 4-nitrophenyl-sulfate (PNP-S) in samples generated in rat small intestine luminal perfusion experiments, an ion-pair HPLC assay coupled with UV detection was set up. The RP-HPLC separation was achieved with a methanol-water mixture (50:50, v/v) containing 0.01 M tetrabutyl-ammonium-bromide with UV detection of the analytes at 290 nm. The isocratic system was operated at ambient temperature and required less than 7 min of chromatographic time. The method provided good enough within-day precision, between-day precision and linearity in the target concentration ranges of 6-1200 microM (PNP) and 2.5-100 microM (PNP-G and PNP-S). The instrumental limit of quantification for PNP-G and PNP-S was found to be 2.7 microM and 2.1 microM, respectively. The assay was applied for determination of PNP, PNP-G and PNP-S in rat small intestine perfusates.

Effect of Bitis gabonica and Dendroaspis angusticeps snake venoms on apoptosis-related genes in human thymic epithelial cells

Certain environmental toxins permanently damage the thymic epithelium, accelerate immune senescence and trigger secondary immune pathologies. However, the exact underlying cellular mechanisms and pathways of permanent immune intoxication remain unknown. The aim of the present study was to demonstrate gene expressional changes of apoptosis-related cellular pathways in human thymic epithelial cells following exposure to snake venom from Bitis gabonica and Dendroaspis angusticeps. Methods: Snake venoms were characterized by analytical methods including reversed phase high-performance liquid chromatography and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, then applied on human thymic epithelial cells (1889c) for 24 h at 10 μg/mL (as used in previous TaqMan Array study). Gene expressional changes restricted to apoptosis were assayed by TaqMan Array (Human Apoptosis Plate). Results: The most prominent gene expressional changes were shown by CASP5 (≈ 2.5 million-fold, confirmed by dedicated quantitative polymerase chain reaction) and CARD9 (0.016-fold) for B. gabonica, and BIRC7 (6.46-fold) and CASP1 (0.30-fold) for D. angusticeps. Conclusion: The observed apoptotic environment suggests that pyroptosis may be the dominant pathway through which B. gabonica and D. angusticeps snake venoms trigger thymic epithelial apoptosis following envenomation.(AU)

Changes in hepatic metabolic enzyme activities and biliary excretion of 4-nitrophenol in streptozotocin induced diabetic rats

Abstract Activity of hepatic metabolic enzymes of glucuronidation and sulfation of 4-nitrophenol (PNP) and biliary excretion of its glucuronide (PNP-G) and sulfate (PNP-S) conjugates have been investigated in control and streptozotocin (STZ)-induced diabetic rats. 500 µM PNP solution was luminally perfused in a cannulated jejunal loop for 90 minutes. It was found that biliary excretion of PNP-G was significantly decreased in the diabetic rats. This effect of STZ could be completely reversed by administration of rapid-acting insulin. Activity of hepatic UDP-glucuronyltransferase and ß-glucuronidase was also depressed by the STZ pretreatment. Administration of insulin antagonized the inhibitory action of STZ on UDP-glucuronyltransferase, but the reduced activity of ß-glucuronidase was not reversed. Biliary excretion of PNP-S was also depressed in the diabetic rats. Whereas, different effects of insulin administration were observed. Namely, the lower biliary excretion rate of PNP-S was not changed after administration of insulin. Activity of the sulfotransferase and the arylsulfatase enzymes was not altered either by STZ pretreatment or by insulin administration. Biliary excretion of PNP was also significantly depressed by STZ and this depression was not changed after insulin administration. The results call attention to hepatobiliary circulation of low molecular weight xenobiotics and their glucuronide and sulfate conjugates

HPLC quantification of 4-nitrophenol and its conjugated metabolites from bile.

An isocratic ion pair RP-HPLC method with UV-Vis detection has been developed and validated for simultaneous analysis of 4-nitrophenol (PNP), 4-nitrophenyl ß-glucuronide (PNP-G), and 4-nitrophenyl sulfate (PNP-S) in rat bile samples using 4-ethylphenol (ETP) as internal standard. Chromatographic separation was achieved on a C(18) column by isocratic elution with a mobile phase consisted of methanol-0.01 M citrate buffer pH 6.2 (47:53 v/v) containing 0.03 M TBAB. The flow rate was 1.0 ml min(-1), the detection was affected at 290 nm. Calibration plots were generated over the concentration range 1-100 µM PNP, PNP-G, PNP-S with a common lower limit of quantification of 2.5 µM. Intra- and inter-day precision and repeatability were determined at six different concentrations. Results obtained by application of the method for determination of PNP, PNP-G and PNP-S in bile fractions collected during intestinal perfusion of PNP in hyperglycemic rats are presented.