In vivo testing of a bioresorbable phosphate-based optical fiber.

Optical fibers have recently attracted a noticeable interest for biomedical applications because they provide a minimally invasive method for in vivo sensing, imaging techniques, deep-tissue photodynamic therapy or optogenetics. The silica optical fibers are the most commonly used because they offer excellent optical properties, and they are readily available at a reasonable price. The fused silica is a biocompatible material, but it is not bioresorbable so it does not decompose in the body and the fibers must be ex-planted after in vivo use and their fragments can present a considerable risk to the patient when the fiber breaks. In contrast, optical fibers made of phosphate glasses can bring many benefits because such glasses exhibit good transparency in ultraviolet-visible and near-infrared regions, and their solubility in water can be tailored by changing the chemical composition. The bioresorbability and toxicity of phosphate glass-based optical fibers were tested in vivo on male laboratory rats for the first time. The fiber was spliced together with a standard graded-index multi-mode fiber pigtail and an optical probe for in vitro pH measurement was prepared by the immobilization of a fluorescent dye on the fiber tip by a sol-gel method to demonstrate applicability and compatibility of the fiber with common fiber optics.

Distribution of metastases in mesorectum is unpredictable: Metastases do not respect tumor localization even in small non-circumferential rectal cancers.

INTRODUCTION: Low anterior resection with total mesorectal excision (TME) is the gold standard for surgical treatment of rectal carcinoma. The radicality of this procedure is negatively counterbalanced by morbidity, lethality, and numerous other complications. Local excision would appear to be an attractive alternative, but its radicality is disputable due to risk of undetected metastasis to the mesorectum. The study aimed to determine the location of mesorectal metastases with respect to circumferentially - located tumors in patients with tumors involving less than one-third of the rectal circumference. MATERIALS AND METHODS: Resected specimens from patients with tumors smaller than one-third of the circumference were divided into: Sector A - tumorous, and Sector B - nontumorous. Group A was created by the pathologist cutting part of the rectal wall with the adjacent mesorectum, as though imitating a full-thickness excision. RESULTS: The study comprised 35 patients with a mean age of 66 years, of which 23 were men (65.7%) and 12 were women (34.2%). Tumors were predominantly (y)pT1-T2; a total of 799 lymph nodes and 5 tumor satellites were examined. Six patients (17.1%) were identified as stage (y)pN+. A total of 3 positive findings (lymph node metastasis or satellites) were detected in 3 patients (8.5%) in tumorous Sector A; and 8 positive findings were detected in 4 patients (11.4%) in non-tumorous Sector B. CONCLUSION: Rectal carcinoma involving one-third of the rectal circumference metastasizes discontinuously, and spreads into parts of the mesorectum beyond the tumor area.

The Importance of Wireless Capsule Endoscopy for Research into the Intestin al Absorption Window of 5-Aminosalicylic Acid in Experimental Pigs.

BACKGROUND: Absorption windows in particular segments of the small intestine can contribute to the development of orally administered drug formulations and can limit the bioavailability of released compounds. OBJECTIVE: The aim of this study was to evaluate use of wireless capsule enteroscopy regarding the disintegration kinetic process of tablets in the small intestine and its comparison with the levels of the model drug (5- aminosalicylic acid; 5-ASA), and its majority metabolite (N-acetyl-5-aminosalicylic acid; N-acetyl-5-ASA) in blood plasma. METHODS: Tablets were endoscopically introduced into the duodenum and their disintegration was monitored using wireless capsule enteroscopy in anaesthetised pigs. In parallel, blood plasma time profiles of the model drug (5-ASA) released from tablets and its metabolite (N-acetyl-5-ASA) were detected. RESULTS: The disintegration of tablets was evident in the proximal jejunum (until the 90-minute mark) and culminated at the 3rd hour. The maximum plasmatic concentration of 5-ASA was reached at the 3rd hour and in the case of its metabolite (N-acetyl-5-ASA) at the 4th hour. CONCLUSION: The study demonstrated the advantage of combination of wireless capsule enteroscopy and bioanalytical determination of pharmacokinetic parameters in an animal experiment to localise the disintegration site of solid dosage form and following kinetics of intestinal absorption of the released active agent.

Preparation of silica nanoparticles loaded with nootropics and their in vivo permeation through blood-brain barrier.

The blood-brain barrier prevents the passage of many drugs that target the central nervous system. This paper presents the preparation and characterization of silica-based nanocarriers loaded with piracetam, pentoxifylline, and pyridoxine (drugs from the class of nootropics), which are designed to enhance the permeation of the drugs from the circulatory system through the blood-brain barrier. Their permeation was compared with non-nanoparticle drug substances (bulk materials) by means of an in vivo model of rat brain perfusion. The size and morphology of the nanoparticles were characterized by transmission electron microscopy. The content of the drug substances in silica-based nanocarriers was analysed by elemental analysis and UV spectrometry. Microscopic analysis of visualized silica nanocarriers in the perfused brain tissue was performed. The concentration of the drug substances in the tissue was determined by means of UHPLC-DAD/HRMS LTQ Orbitrap XL. It was found that the drug substances in silica-based nanocarriers permeated through the blood brain barrier to the brain tissue, whereas bulk materials were not detected in the brain.

Impact of tacrine and 7-methoxytacrine on gastric myoelectrical activity assessed using electrogastrography in experimental pigs.

OBJECTIVES: Tacrine was the first acetylcholinesterase inhibitor approved for therapy of Alzheimer's disease. It has currently been withdrawn in some countries mostly due to the risk of hepatotoxicity and might be replaced by its derivate 7-methoxytacrine (7-MEOTA). The aim of this study was to assess the impact of these two compounds on gastric myoelectrical activity by means of surface cutaneous electrogastrography (EGG). METHODS: Twelve pigs (Sus scrofa f. domestica, weighing 30-35 kg) entered the study. A single dose of tacrine (200 mg i.m., n=6) or 7-MEOTA (200 mg i.m., n=6) was administrated. All EGG recordings were performed under general anaesthesia in the morning after 24 hours of fasting. Basal (30 minutes) and study recordings (150 minutes) were accomplished using an EGG stand (MMS, Enschede, the Netherlands). Results were expressed as dominant frequency of gastric slow waves, power analysis (areas of amplitudes) and power ratio assessment (ratio of the areas of amplitudes after and before study drug administration). RESULTS: Tacrine decreased EGG dominant frequency 10 minutes after its administration (from basal 3.1±0.6 to 2.8±0.6 cycles per minute; p=0.014). Tacrine induced a non-significant 60-minute increase of the power (with maximal value 493±533 µV2 at 20 minutes) and power ratio (with maximal value 2.04±3.4 at 10 minutes). Tacrine caused substantial gastric arrhythmia. 7-MEOTA did not influence dominant frequency of gastric slow waves significantly. 7-MEOTA caused a short-term late increase of the power ratio at 60 minutes (6.3±11.2; p=0.003). Blood cholinesterase activity did not correlate with any EGG parameter either after tacrine or 7-MEOTA at any time. CONCLUSIONS: Tacrine and 7-MEOTA have different impacts on EGG. Tacrine decreased dominant frequency and induced long-lasting gastric arrhythmia. 7-MEOTA caused a short-term late increase of the EGG power in experimental pigs.

Distribution study of atorvastatin and its metabolites in rat tissues using combined information from UHPLC/MS and MALDI-Orbitrap-MS imaging.

The combination of ultrahigh-resolution mass spectrometry imaging (UHRMSI) and ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC/MS/MS) was used for the identification and the spatial localization of atorvastatin (AT) and its metabolites in rat tissues. Ultrahigh-resolution and high mass accuracy measurements on a matrix-assisted laser desorption/ionization (MALDI)-Orbitrap mass spectrometer allowed better detection of desired analytes in the background of matrix and endogenous compounds. Tandem mass spectra were also used to confirm the identification of detected metabolites in complex matrices. The optimization of sample preparation before imaging experiments included the tissue cryogenic sectioning (thickness 20 µm), the transfer to stainless steel or glass slide, and the selection of suitable matrix and its homogenous deposition on the tissue slice. Thirteen matrices typically used for small molecule analysis, e.g., 2,5-dihydroxybenzoic acid (DHB), 1,5-diaminonaphthalene (DAN), 9-aminoacridine (AA), etc., were investigated for the studied drug and its metabolite detection efficiency in both polarity modes. Particular matrices were scored based on the strength of extracted ion current (EIC), relative ratio of AT molecular adducts, and fragment ions. The matrix deposition on the tissue for the most suitable matrices was done by sublimation to obtain the small crystal size and to avoid local variations in the ionization efficiency. UHPLC/MS profiling of drug metabolites in adjacent tissue slices with the previously optimized extraction was performed in parallel to mass spectrometry imaging (MSI) measurements to obtain more detailed information on metabolites in addition to the spatial information from MSI. The quantitation of atorvastatin in rat liver, serum, and feces was also performed.

HI-6 oxime (an acetylcholinesterase reactivator): blood plasma pharmacokinetics and organ distribution in experimental pigs.

OBJECTIVES: Oxime HI-6 DMS (dimethanesulfonate) is an asymmetric bis-pyridinium aldoxime and essential acetylcholinesterase (AChE) reactivator. The high effectiveness is due to its wide spectrum of therapeutic activity against different structures of nerve agents. Aim of this study was to compare plasma time profiles and tissue distribution (to delimitation of potential toxicity risks) after its intramuscular (i.m.) and intragastric (i.g.) administration to experimental pigs. METHODS: The study entered female Landrace pigs (Sus scrofa f. domestica), 4-5 months old animals, 29 ± 3.2 kg of body weight. Before the HI-6 DMS administration (i.m. injection or i.g. using a gastric tube), vena auricularis was cannulated (under general anaesthesia) for collection of blood samples. The tissue distribution study was carried out at expected t-max. Concentrations of HI-6 DMS in blood plasma and other tissue samples were detected by means of HPLC method. RESULTS: Fast absorption after i.m. administration, relatively slow absorption and no even elimination after i.g. administration were found. Tissue distribution showed low accumulation in the liver, but a higher content in the kidneys and high concentrations in the brain and gastrointestinal wall. CONCLUSIONS: Plasma time profiles after i.g. administration has a prolonged pharmacokinetics. Tissue distribution study showed potential side effects to the stomach due to a higher accumulation of HI-6 in this tissue after i.g. administration but not after a standard i.m. administration. Higher content of HI-6 in the kidneys after i.m. administration suggests the main way of the oxime elimination.

Intravenous application of HI-6 salts (dichloride and dimethansulphonate) in pigs: comparison with pharmacokinetics profile after intramuscular administration.

OBJECTIVES: Oxime HI-6 is an acetylcholinesterase reactivator therapeutically efficient against nerve agents. Because of their physico-chemical properties, oximes are typically applied intramuscularly (i.m.). This route of administration has also some disadvantages, and alternative strategies ought to be examined. We evaluated the pharmacokinetic profiles of two HI-6 salts after their intravenous (i.v.) administration, and compare the results with the known pharmacokinetics after i.m. administration. METHODS: Pigs were administered with HI-6 salts (i.v), either HI-6 dichloride (10.71 mg/kg) or molar equivalent HI-6 dimethansulphonate (13.59 mg/kg). Doses of the HI-6 salts corresponded with a standard HI-6 dichloride dose in one autoinjector (500 mg) and were recalculated for one kilogram of body weight. RESULTS: The main pharmacokinetic parameters are comparable after i.v. and i.m. HI-6 administration. The compared pharmacokinetic parameters were half-life, terminal rate constant, mean residence time of the molecule in the body, clearance, and the apparent volume in the terminal phase. The bioavailability after i.m. administration was comparable with that of i.v.; these results suggest that the oxime is well released from the muscle depot. Significant differences were found in parameters Cmax and Tmax which are important in cases of emergency when rapidity and bioavailability are paramount for the success of treatment. CONCLUSIONS: I.v. administration should solve the problem of rapid clearance. Infusion or bolus administration may be considered as a logical subsequent step in oxime treatment strategy. The main advantage is in maintenance of an effective therapeutic plasma concentration, a more easily achievable effective therapeutic concentration, and fewer local adverse reactions.

Impact of paraoxon followed by acetylcholinesterase reactivator HI-6 on gastric myoelectric activity in experimental pigs.

OBJECTIVES: Organophosphorus compounds represent nerve agents, pesticides and several industrial compounds. Treatment after exposure to organophosphates involves the use of parasympatolytics, acetylcholinesterase (AChE) reactivators/modulators and anticonvulsive drugs. Wider clinical use of several AChE reactivators/modulators might be limited because of possible side effects, including gastrointestinal toxicity. In this study we evaluated the effect of paraoxon and an AChE reactivator (HI-6) on the gastric myoelectric activity in experimental pigs. METHODS: Six female experimental pigs (mean weight 33 kg) entered the study. Intramuscular paraoxon (1.5 g) was administrated after the baseline gastric electrogastrography (EGG) recording, followed by HI-6 dimethansulphonate (1.5 g i.m.) 10 min. later. A further ten 15-minute-interval EGG recordings were performed. Running spectral analysis was used for the elemental evaluation of the EGG. The results were expressed as dominant frequency of slow waves at all intervals of EGG recordings. EGG power analysis was performed in all animals. RESULTS: Paraoxon induced a non-significant decrease of dominant frequency (2.8±0.6 vs. 2.6±0.5 cycles per min.; p=0.092). Subsequent administration of HI-6 normalised dominant frequency to basal values and increased it significantly within the subsequent 30 minutes (3.0±0.4; p<0.001). Paraoxon administration did not influence the power (within a 10-minute exposure). However, the amplitudes increased significantly 90 minutes after administration of HI-6 (819±109 vs. 5054±732 µV2; p<0.001). CONCLUSIONS: AChE reactivator HI-6 blocked the gastric effect of paraoxon significantly. Subsequent myoelectric changes in the dominant frequency and power were executed by HI-6. The effect of paraoxon was non-significant.

Transintestinal transport mechanisms of 5-aminosalicylic acid (in situ rat intestine perfusion, Caco-2 cells) and Biopharmaceutics Classification System.

The aim of the study was 1) to estimate permeability of 5-aminosalicylic acid (5-ASA), 2) to categorize 5-ASA according to BCS (Biopharmaceutics Classification System), and 3) to contribute to determination of 5-ASA transintestinal transport and biotransformation mechanisms. The in situ rat intestine perfusion was used as an initial method to study 5-ASA transport. The amount of 5-ASA (released from tablet) transferred into portal circulation reached 5.79 ± 0.24%. During this transport, the intestinal formation of 5-ASA main metabolite (N-ac-5-ASA) occurred. N-ac-5-ASA was found in perfusate both from intestinal lumen and from v. portae. In in vitro Caco-2 monolayers, transport of 5-ASA (10-1000 µmol/l) was studied in apical-basolateral and basolateral-apical direction (iso-pH 7.4 conditions). The transport of total 5-ASA (parent drug plus intracellularly formed N-ac-5-ASA) was linear with time, concentration- and direction-dependent. Higher basolateral-apical (secretory) transport was mainly caused by higher transport of the metabolite (suggesting metabolite efflux transport). Transport of 5-ASA (only parent drug) was saturable (transepithelial carrier-mediated) at low doses, dominated by passive, paracellular process in higher doses which was confirmed by increased 5-ASA transport using Ca2+-free transport medium. The estimated low 5-ASA permeability and its low solubility enable to classify 5-ASA as BCS class IV.

The effect of general anaesthesia on gastric myoelectric activity in experimental pigs.

BACKGROUND: Surface electrogastrography (EGG) is a non-invasive method for clinical assessment of gastric myoelectrical activity. Different forms of general anaesthesia might have various effects on porcine EGG. The aim of this study was to evaluate the impact of different anaesthetic agents on EGG in experimental pigs. METHODS: Four 15-minute EGG intervals were recorded and analysed. A baseline EGG recording was started 20 minutes after intramuscular injection of ketamine and azaperone (periods A and B). Four different regimens of general anaesthesia followed immediately after the baseline EGG (5 pigs in each experimental group): thiopental, isoflurane, nitrous oxide and isoflurane plus nitrous oxide. EGG recordings followed for the next 30 minutes under general anaesthesia (periods C and D). The dominant frequencies of slow waves were compared between the baseline intervals A and B and periods C and D under general anaesthesia. RESULTS: The mean dominant frequency was within the normal range (2.3 - 3.5 cycles per minute) in all animals in all regimens. Thiopental general anaesthesia did not influence any change of the dominant frequency of slow waves. Nitrous oxide general anaesthesia increased the dominant frequency of slow waves in a statistically significant manner (baseline: 2.93 ± 0.53 and 3.01 ± 0.53; under general anaesthesia: 3.25 ± 0.34 and 3.29 ± 0.38 cycles per minute; p < 0.001, p = 0.003, p < 0.001, p < 0.001). Nitrous oxide together with isoflurane induced a statistically significant decrease of dominant frequency in the last 15-minute interval (2.66 ± 0.55 cycles per minute) compared to the baseline recording (2.81 ± 0.49; p = 0.030). CONCLUSIONS: All changes of porcine gastric myoelectric activity assessed by the dominant frequency of slow waves during EGG remained within the normal range although some of them achieved statistical significance. Thus all tested agents used for general anaesthesia can be recommended in preclinical studies with porcine models focused on gastric myoelectric activity without any risk of compromising the results. Thiopental seems to be the most suitable as it did not cause any changes at all.

Experimental administration of the probiotic Escherichia coli strain Nissle 1917 results in decreased diversity of E. coli strains in pigs.

The strain Escherichia coli Nissle 1917 (EcN) is widely used as an efficient probiotic in therapy and prevention of human infectious diseases, especially of the intestinal system. Concurrently, small adult pigs are being used as experimental omnivore models to study human gastrointestinal functions. EcN bacteria were applied to 6 adult healthy female pigs in a 2-week trial. 6 Control animals remained untreated. Altogether, 164 and 149 bacterial strains were isolated from smear samples taken from gastrointestinal mucosa in the experimental and control group, respectively. Each individual E. coli strain was then tested for the presence of 29 bacteriocin-encoding determinants as well as for DNA markers of A, B1, B2 and D phylogenetic groups. A profound reduction of E. coli genetic variance (from 32 variants to 13 ones, P = 0.0006) was found in the experimental group, accompanied by a lower incidence of bacteriocin producers in the experimental group when compared to control (21.3 and 34.9%, respectively; P = 0.007) and by changes in the incidence of individual bacteriocin types. The experimental administration of EcN strain was not sufficient for stable colonization of porcine gut, but induced significant changes in the enterobacterial microbiota.

Absorption kinetics of 5-aminosalicylic acid in rat: influence of indomethacin-induced gastrointestinal lesions and Escherichia Coli Nissle 1917 medication.

OBJECTIVES: The therapeutic effect of probiotics has been studied in many clinical and experimental studies but no data exist concerning the influence of probiotics on pharmacokinetics of contemporary administered drugs. In this paper, we describe the influence of indomethacin-induced gastrointestinal lesions and Escherichia Coli Nissle 1917 medication on absorption of 5-aminosalicylic acid and its metabolite N-acetyl-5-aminosalicylic acid in rat. METHODS: 5-aminosalicylic acid (5-ASA) was given orally to rat using gastric probe as a suspension (25 mg/kg). The plasma time profiles of 5-ASA and its metabolite were compared between Group A (animals medicated with a suspension of Escherichia coli Nissle 1917 [EcN] in dose of 5 × 108 CFUs/day for 14 consecutive days), Group B (animals with indomethacin [IND]-induced gastrointestinal lesions; single dose of 25 mg/kg of IND), Group C (simultaneous administration of EcN and IND), and Group D (control animals without any medication). The blood samples for HPLC analysis has been taken from incannulated vena jugularis in time 30, 60, 90, 120, 180, 240, 360 min after 5-ASA administration to rat. RESULTS: The pharmacokinetics of 5-ASA was not significantly changed by EcN medication (Group A) in comparison to control animals (Group D). The significantly elevated absorption (AUC and cmax) of 5-ASA was found in animals with induced gastro-enteropathy with concurrently medicated with EcN (Group C) when compred to controls. In the case of metabolite N-acetyl-5-ASA, statistically no-significant differences were found between groups. CONCLUSIONS: Simultaneous probiotics (EcN) medication did not affect absorption 5-ASA from intestinal tract (the main site of ASAs action).

Electrogastrography in experimental pigs: the influence of gastrointestinal injury induced by dextran sodium sulphate on porcine gastric erythromycin-stimulated myoelectric activity.

OBJECTIVES: Electrogastrography (EGG) is a non-invasive investigation of gastric myoelectrical activity. The aim of study was to evaluate the impact of erythromycin on EGG in gastrointestinal toxic injury induced by dextran sodium sulphate (DSS) in experimental pigs. METHODS: The experiments were carried out on 12 adult pigs (weighing 30-35 kg). EGG was recorded using Digitrapper equipment (Synectics Medical AB, Stockholm). Running spectrum activity was used for EGG evaluation. There were two groups of animals: Group I: 6 controls with erythromycin administration (1,600 mg intragastrically); Group II: 6 animals treated with DSS (for 5 days, 0.25 g/kg per day in a dietary bolus) followed by erythromycin administration. Baseline and subsequent six separate 30-minute EGG-recordings (from time 0 to 360 min) were accomplished in each animal. RESULTS AND CONCLUSION: A total of 84 records were analysed. Baseline dominant frequency of slow waves was fully comparable in both groups. In Group I, there was a significant increase in dominant frequency after erythromycin administration (maximum between 240-360 min). There was a flat non-significant and delayed increase in dominant frequency after erythromycin administration in Group II. The difference between Group I and II at particular time intervals was not significant but a diverse trend was evident. EGG recording enables us to register a gastric myoelectrical effect of prokinetic drugs. Erythromycin induced a significant increase in the dominant frequency of slow waves. DSS caused toxic injury to the porcine gastrointestinal tract responsible for the delayed and weaker myoelectrical effect of erythromycin in experimental animals.

High-performance liquid chromatographic determination of tiapride and its phase I metabolite in blood plasma using tandem UV photodiode-array and fluorescence detection.

New bioanalytical SPE-HPLC-PDA-FL method for the determination of the neuroleptic drug tiapride and its N-desethyl metabolite was developed, validated and applied to xenobiochemical and pharmacokinetic studies in humans and animals. The sample preparation process involved solid-phase extraction of diluted plasma spiked with sulpiride (an internal standard) using SPE cartridges DSC-PH Supelco, USA. Chromatographic separation of the extracts was performed on a Discovery HS F5 250 mm × 4 mm (Supelco) column containing pentafluorophenylpropylsilyl silica gel. Mobile phase (acetonitrile-0.01 M phosphate buffer pH=3, flow rate 1 ml min(-1)) in the gradient mode was employed in the HPLC analysis. Tandem UV photodiode-array→fluorescence detection was used for the determination of the analytes. Low concentrations of tiapride and N-desethyl tiapride were determined using a more selective fluorescence detector (λ(exc.)/λ(emiss.)=232 nm/334 nm), high concentrations (500-6000 pmol ml(-1)) using a UV PDA detector at 212 nm with a linear response. Each HPLC run lasted 15 min. Lower limits of quantification (LLOQ) for tiapride (N-desethyl tiapride) were found to be 8.24 pmol ml(-1) (10.11 pmol ml(-1)). The recoveries of tiapride ranged from 89.3 to 94.3%, 81.7 to 86.8% for internal standard sulpiride and 90.9 to 91.8% for N-desethyl tiapride.

Bacteriocinogeny in experimental pigs treated with indomethacin and Escherichia coli Nissle.

AIM: To evaluate bacteriocinogeny in short-term high-dose indomethacin administration with or without probiotic Escherichia coli Nissle 1917 (EcN) in experimental pigs. METHODS: Twenty-four pigs entered the study: Group A (controls), Group B (probiotics alone), Group C (indomethacin alone) and Group D (probiotics and indomethacin). EcN (3.5×10(10) bacteria/d for 14 d) and/or indomethacin (15 mg/kg per day for 10 d) were administrated orally. Anal smears before and smears from the small and large intestine were taken from all animals. Bacteriocin production was determined with 6 different indicator strains; all strains were polymerase chain reaction tested for the presence of 29 individual bacteriocin-encoding determinants. RESULTS: The general microbiota profile was rather uniform in all animals but there was a broad diversity in coliform bacteria (parallel genotypes A, B1, B2 and D found). In total, 637 bacterial strains were tested, mostly Escherichia coli (E. coli). There was a higher incidence of non-E. coli strains among samples taken from the jejunum and ileum compared to that of the colon and rectum indicating predominance of E. coli strains in the large intestine. Bacteriocinogeny was found in 24/77 (31%) before and in 155/560 (28%) isolated bacteria at the end of the study. Altogether, 13 individual bacteriocin types (out of 29 tested) were identified among investigated strains. Incidence of four E. coli genotypes was equally distributed in all groups of E. coli strains, with majority of genotype A (ranging from 81% to 88%). The following types of bacteriocins were most commonly revealed: colicins Ia/Ib (44%), microcin V (18%), colicin E1 (16%) and microcin H47 (6%). There was a difference in bacteriocinogeny between control group A (52/149, 35%) and groups with treatment at the end of the study: B: 31/122 (25%, P=0.120); C: 43/155 (28%, P=0.222); D: 29/134 (22%, P=0.020). There was a significantly lower prevalence of colicin Ib, microcins H47 and V (probiotics group, P<0.001), colicin E1 and microcin H47 (indomethacin group, P<0.001) and microcins H47 and V (probiotics and indomethacin group, P=0.025) compared to controls. Escherichia fergusonii (E. fergusonii) was identified in 6 animals (6/11 isolates from the rectum). One strain was non-colicinogenic, while all other strains of E. fergusonii solely produced colicin E1. All animals started and remained methanogenic despite the fact that EcN is a substantial hydrogen producer. There was an increase in breath methane (after the treatment) in 5/6 pigs from the indomethacin group (C). CONCLUSION: EcN did not exert long-term liveability in the porcine intestine. All experimental pigs remained methanogenic. Indomethacin and EcN administered together might produce the worst impact on bacteriocinogeny.

Pharmacokinetics and organ distribution of fluorescein in experimental pigs: an input study for confocal laser endomicroscopy of the gastrointestinal tract.

OBJECTIVE: Confocal laser scanning endomicroscopy (CLSE) is a diagnostic technology that produces virtual histology of the mucosal layer using fluorescence technique. Fluorescein (FSC) is the most commonly used fluorescence agent. Fluorescence light coming from a horizontal special focal plane is detected during confocal laser endomicroscopy of the gastrointestinal tract. FSC causes intensive yellowish discoloration of tissues, including skin and mucous membranes. This pre-clinical study was aimed to evaluate the tissue distribution and pharmacokinetics of FSC after its intravenous administration. METHODS: The study was performed in an adult experimental pig. A reversed-phase high-performance liquid chromatographic method with fluorescence detection was used for the determination of fluorescein in blood plasma and tissue samples. RESULTS AND CONCLUSION: The pharmacokinetic study of fluorescein determined the optimum time interval for diagnostic scanning (5-10 min.) The biodistribution study of fluorescein (aimed on the potential organ accumulation) proved the high concentration in the renal system followed by levels in bile > lung > adipose tissue > all other organs (including gastrointestinal wall) and these were relatively similar to each other. Fluorescein has a significantly low distribution in the brain (contrast with the level in adipose tissue indicates the low ability to penetrate the blood-brain barrier).

Preclinical electrogastrography in experimental pigs.

Surface electrogastrography (EGG) is a non-invasive means of recording gastric myoelectric activity or slow waves from cutaneous leads placed over the stomach. This paper provides a comprehensive review of preclinical EGG. Our group recently set up and worked out the methods for EGG in experimental pigs. We gained our initial experience in the use of EGG in assessment of porcine gastric myoelectric activity after volume challenge and after intragastric administration of itopride and erythromycin. The mean dominant frequency in pigs is comparable with that found in humans. EGG in experimental pigs is feasible. Experimental EGG is an important basis for further preclinical projects in pharmacology and toxicology.

Wireless video capsule enteroscopy in preclinical studies: methodical design of its applicability in experimental pigs.

The aim of this project was to develop a methodology to introduce wireless video capsule endoscopy in preclinical research. Five mature female pigs (Sus scrofa domestica) were selected for the study. Capsule endoscopes (the EndoCapsule system; Olympus) were introduced into the duodenum endoscopically in each of the animals. The life span of batteries (i.e., total time of endoscopy recording) was 487-540 min (median 492 min). The capsule endoscope reached the cecum during enteroscopy once (after 7 h 57 min), in the remaining cases, endoscopy recordings terminated in the distal or terminal ileum. All capsule enteroscopies found a normal pattern of the small intestine. The intestinal lumen is narrower, transverse folds are sparse or even absent, villi are wider but less prominent in pigs compared to humans. Capsule endoscopy in experimental pigs will be helpful for future trials on injury of different drugs and xenobiotics to the small bowel.

Wireless capsule endoscopy in enteropathy induced by nonsteroidal anti-inflammatory drugs in pigs.

AIM: The aim of this study is to evaluate the diagnostic yield of capsule endoscopy in nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy in pigs. MATERIALS AND METHODS: Indomethacin (400 mg/day) was administrated orally for 10 days to eight female pigs weighing 36.3+/-2.4 kg. Afterwards, capsule endoscopy was performed, using the EndoCapsule system (Olympus Optical Co., Tokyo, Japan). The following morning, pharmacological euthanasia and immediate autopsy were performed. RESULTS: Small bowel injury compatible with NSAID-induced enteropathy was observed in 7/8 animals. The most common lesions were red spots and erosions. Ulcers and small intestinal bleeding were identified sporadically. Sensitivity and specificity of capsule endoscopy were 83.3% and 95.8%, respectively. CONCLUSION: Our results indicate that wireless capsule endoscopy is a highly accurate noninvasive method for evaluation of experimental NSAID-induced enteropathy.