Decreased Plasma Levels of Kynurenine and Kynurenic Acid in Previously Treated and First-Episode Antipsychotic-Naive Schizophrenia Patients.

Tryptophan (TRP) catabolites exert neuroactive effects, with the plethora of evidence suggesting that kynurenic acid (KYNA), a catabolite of the kynurenine pathway (KP), acts as the regulator of glutamate and acetylcholine in the brain, contributing to the schizophrenia pathophysiology. Newer evidence regarding measures of KP metabolites in the blood of schizophrenia patients and from the central nervous system suggest that blood levels of these metabolites by no means could reflect pathological changes of TRP degradation in the brain. The aim of this study was to investigate plasma concentrations of TRP, kynurenine (KYN) and KYNA at the acute phase and remission of schizophrenia in a prospective, case-control study of highly selected and matched schizophrenia patients and healthy individuals. Our study revealed significantly decreased KYN and KYNA in schizophrenia patients (p < 0.001), irrespective of illness state, type of antipsychotic treatment, number of episodes or illness duration and no differences in the KYN/TRP ratio between schizophrenia patients and healthy individuals. These findings could be interpreted as indices that kynurenine pathway might not be dysregulated in the periphery and that other factors contribute to observed disturbances in concentrations, but as our study had certain limitations, we cannot draw definite conclusions. Further studies, especially those exploring other body compartments that participate in kynurenine pathway, are needed.

Evaluation of Apple Pomace Flour Obtained Industrially by Dehydration as a Source of Biomolecules with Antioxidant, Antidiabetic and Antiobesity Effects.

Apple pomace flour (APF) obtained at industrial scale level by the application of innovative technological process (dehydration (5 h, T ≤ 55 °C), grinding (300 µm)) was evaluated as a source of bioactive compounds with antioxidative, antiobesity and antidiabetic effects. Proximate composition, individual (HPLC-DAD-MS/MS) and total phenols (TPC) as well as flavonoids content (TFC), antioxidant (AO) activity (DPPH, ABTS, HPMC), water and oil holding capacity (WHC and OHC) of APFs obtained from apple pomace from mixed and individual apple cultivars grown conventionally and organically were compared. The effect of APF supplementation on the glycaemic status and glucose tolerance (oral glucose tolerance test (OGTT)) of C57BL/6J mice exposed to high-fat and sucrose diet was examined. High K content (4.2-6.4 g/kg), dietary fibres (35-45 g/100 g), TPC (4.6-8.1 mg GAE/g), TFC (18.6-34.6 mg QE/g), high water and oil holding capacity (4.7-6.4 and 1.3-1.6 g/g) were observed in the APFs. Content of major phenols (phlorizin, chlorogenic acid, quercetin), TPC and TFC correlated highly with prominent AO activity. APF supplementation lowered the increase of body weight gain and blood glucose, and improved glucose tolerance significantly. Health-promoting biomolecules, AO activity, functional properties and prevention of diet-driven glucose metabolism disorders pave the way to APF exploitation in human nutrition.

A New Look at an Old Drug: Cumulative Effects of Low Ribavirin Doses in Amphetamine-Sensitized Rats.

BACKGROUND: Psychotic states related to psychostimulant misuse in patients with hepatitis C virus infection may complicate acceptance and reaction to antiviral treatment. This observation equally applies to the widely used ribavirin therapy. OBJECTIVE: We examined psychomotor and body weight gain responses to low ribavirin doses after cessation of intermittent amphetamine treatment in adult rats to assess its role in neurobehavioral outcome during psychostimulant withdrawal. METHOD: The model of amphetamine-induced (1.5 mg/kg/day, i.p., 7 consecutive days) motor sensitization and affected body weight gain was established in adult male Wistar rats. Then, additional cohort of amphetaminesensitized rats was subjected to saline (0.9% NaCl; 1 mL/kg/day; i.p.) or ribavirin (10, 20 and 30 mg/kg/day, i.p.) treatment for 7 consecutive days. Animals' motor activity in a novel environment was monitored after the 1st and the 7th saline/ribavirin injection. Body weight gain was calculated as appropriate. Determination and quantification of ribavirin in the brain tissue were performed also. RESULTS: The 1st application of ribavirin to amphetamine-sensitized rats affected/decreased their novelty-induced motor activity only at a dose of 30 mg/kg. After the 7th application, ribavirin 30 mg/kg/day still decreased, while 10 and 20 mg/kg/day increased novelty-induced motor activity. These behavioral effects coincided with the time required to reach maximum ribavirin concentration in the brain. Body weight gain during withdrawal was not influenced by any of the doses tested. CONCLUSION: Ribavirin displays central effects that in repeated treatment, depending on the applied dose, could significantly influence psychomotor response but not body weight gain during psychostimulant/amphetamine withdrawal.

In vitro and in vivo antimelanoma effect of ethyl ester cyclohexyl analog of ethylenediamine dipropanoic acid.

Melanoma, an aggressive skin tumor with high metastatic potential, is associated with high mortality and increasing morbidity. Multiple available chemotherapeutic and immunotherapeutic modalities failed to improve survival in advanced disease, and the search for new agents is ongoing. The aim of this study was to investigate antimelanoma effects of O,O-diethyl-(S,S)-ethylenediamine-N,N'di-2-(3-cyclohexyl) propanoate dihydrochloride (EE), a previously synthesized and characterized organic compound. Mouse melanoma B16 cell viability was assessed using acid phosphatase, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, sulforhodamine B, and lactate dehydrogenase assays. Apoptosis and autophagy were investigated using flow cytometry, fluorescence and electron microscopy, and western blotting. In vivo antitumor potential was assessed in subcutaneous mouse melanoma model after 14 days of treatment with EE. Tumor mass and volume were measured, and RT-PCR was used for investigating the expression of autophagy-related, proapoptotic, and antiapoptotic molecules in tumor tissue. Investigated organic compound exerts significant cytotoxic effect against B16 cells. EE induced apoptosis, as confirmed by phosphatidyl serine externalisation, caspase activation, and ultrastructural features typical for apoptosis seen on fluorescence and electron microscopes. The apoptotic mechanism included prompt disruption of mitochondrial membrane potential and oxidative stress. No autophagy was observed. Antimelanoma action and apoptosis induction were confirmed in vivo, as EE decreased mass and volume of tumors, and increased expression of several proapoptotic genes. EE possesses significant antimelanoma action and causes caspase-dependent apoptosis mediated by mitochondrial damage and reactive oxygen species production. Decrease in tumor growth and increase in expression of proapoptotic genes in tumor tissue suggest that EE warrants further investigation as a candidate agent in treating melanoma.

Reversion of methacholine induced bronchoconstriction with inhaled diazepam in patients with asthma.

BACKGROUND: Benzodiazepines have a direct bronchodilatory effect. Methacholine is a non-selective muscarinic receptor agonist causing bronchoconstriction. AIM: To examine the effects of inhaled benzodiazepines, modulating bronchoconstriction induced by methacholine in patients with asthma. PATIENTS AND METHODS: Twelve patients with well controlled asthma were studied. On the first day, after determining the initial values of pulmonary function, a dose response curve was carried out with progressive doses of methacholine. After the last dose, when at least a 20% drop of the initial forced expiratory volume in the first second (FEV1) was achieved, vital capacity (VC) and FEV1 were measured at 7, 15 and 30 minutes after provocation. On the second day a diazepam aerosol was inhaled by the patients prior to the same protocol with methacholine. RESULTS: In the first day of testing, methacholine inhalation (6 mg/mL) led to a significant drop in FEV1 from 2.98 to 1.69 L. On the second day of study, in the same patients, previous inhalation with diazepam reduced the changes of FEV1 after inhalation of methacholine. This parameter decreased from 2.48 to 2.21 L. CONCLUSIONS: Inhalation of benzodiazepines reduce bronchoconstriction after a methacholine challenge in patients with asthma.

Reversion of methacholine induced bronchoconstriction with inhaled diazepam in patients with asthma / Bloqueo de la respuesta bronco constrictora a metacolina con diazepam inhalado en pacientes con asma

Background: Benzodiazepines have a direct bronchodilatory effect. Methacholine is a non-selective muscarinic receptor agonist causing bronchoconstriction. Aim: To examine the effects of inhaled benzodiazepines, modulating bronchoconstriction induced by methacholine in patients with asthma. Patients and Methods: Twelve patients with well controlled asthma were studied. On the first day, after determining the initial values of pulmonary function, a dose response curve was carried out with progressive doses of methacholine. After the last dose, when at least a 20% drop of the initial forced expiratory volume in the first second (FEV1) was achieved, vital capacity (VC) and FEV1 were measured at 7, 15 and 30 minutes after provocation. On the second day a diazepam aerosol was inhaled by the patients prior to the same protocol with methacholine. Results: In the first day of testing, methacholine inhalation (6 mg/mL) led to a significant drop in FEV1 from 2.98 to 1.69 L. On the second day of study, in the same patients, previous inhalation with diazepam reduced the changes of FEV1 after inhalation of methacholine. This parameter decreased from 2.48 to 2.21 L. Conclusions: Inhalation of benzodiazepines reduce bronchoconstriction after a methacholine challenge in patients with asthma.

Antecedentes: Las benzodiacepinas tienen un efecto broncodilatador directo. La metacolina es un agonista muscarínico que causa bronco constricción. Objetivo: Evaluar el efecto modulador de la inhalación de diazepam sobre la bronco constricción inducida por metacolina. Pacientes y Métodos: Se estudiaron 12 pacientes con asma bien controlada. En el primer día, se determinó la curva dosis respuesta de parámetros de función pulmonar a una dosis progresiva de metacolina. Después de la última dosis, cuando se consiguió un 20% de reducción en la capacidad vital forzada en el primer segundo (FEV1), se midió FEV1 y la capacidad vital (CV) a los 7, 15 y 30 min después de la provocación. En el segundo día los pacientes se inhalaron con diazepam antes de hacer la prueba con metacolina. Resultados: En el primer día, el FEV1 bajo de 2,98 a 1,69 l con 6 mg/ml de metacolina. En el segundo día, la inhalación de diazepam redujo la respuesta a metacolina con una reducción de FEV1 de 2,48 a 2,21 L. Conclusiones: La benzodiacepinas reducen la respuesta de vasoconstricción a metacolina.

Biomarkers of oxidative damage and antioxidant enzyme activities in pre-dialysis Balkan endemic nephropathy patients.

AIM: To obtain more insight into molecular mechanisms underlying oxidative stress in Balkan endemic nephropathy (BEN), biomarkers of oxidative stress and antioxidant enzyme activities were studied in 38 pre-dialysis BEN patients, 21 healthy BEN family members and 36 healthy subjects from non-endemic areas. METHODS: Protein thiol groups (P-SH), antioxidant enzyme activities [superoxide dismutase (SOD) and glutathione peroxidase (GPX)], were determined in plasma spectrophotometrically, while malondialdehyde adducts (MDA) by enzyme immunoassay. RESULTS: BEN patients had significantly lower plasma GPX activity in comparison with values for both control groups (p = 0.016), gradually decreasing with kidney function impairment estimated by glomerular filtration rate (r = 0.53, p = 0.002). GPX activity was inversely correlated with serum urea (r = -0.627, p < 0.001), creatinine (r = -0.53, p < 0.05), urinary excretion of protein and α1-microglobulin (r = -0.44, p = 0.012; r = -0.50, p < 0.007). Significant upregulation of SOD activity was observed in healthy BEN family members (p < 0.05). While the concentration of MDA adducts was similar in all three groups, BEN patients and healthy BEN family members exhibited increased protein damage, based on fewer P-SH groups in comparison with subjects from non-BEN areas (p = 0.085; p = 0.014, respectively). CONCLUSIONS: Based on our results on increased oxidative protein damage in both pre-dialysis BEN patients and healthy BEN family members, it can be speculated that individuals from BEN areas, in general, are chronically exposed to some prooxidant environmental compounds. Moreover, decrease in plasma GPX activity, as a consequence of impaired kidney function, could further affect oxidative status in BEN patients.

Histological characteristics and markers of proliferation and differentiation in rat brain with experimental glioma.

BACKGROUND/AIM: The cell line C6 is a continuous cell line of rat glioma and, as a transplantable line, is frequently used for induction into in vivo model of primary brain tumor. It is believed that, pursuant to its histological traits and biological behavior, this experimental tumor corresponds to human anaplastic astrocytoma of grade II/III, which is characterized by proliferative and invasive potency, and marked cell differentiation. The aim of this study was to determine macroscopic analysis of rat brain with implanted tumor during tumorigenesis, histological features of tumor cells of induced brain tumor and markers of proliferation (proliferation cell nuclear antigen - PCNA, cytokeratin - CK 19) and differentiation (glial fibrillary acidic protein -GFAP) in rat brain with implanted tumor. METHODS: To determine histological structure of the brain with implanted C6 cells, we used brain sections stained for hematoxylin-eosin or kresyl violet, whereas other sections were immunohistochemically stained for GFAP, CK 19 and PCNA. RESULTS: A statistically significant difference in weights of the left and right brain hemispheres with implanted tumors during tumorigenesis in as soon as 7 days from the day of inducing tumors was revealed. The tumor was of cellular type, with distinct pleomorphism of cells and frequent hyperchromasia of the nucleus. Immunohistochemical staining for PCNA revealed a significant number of positive cells on the days 7, 14 and 21 day following the implantation of C6 cells. CK 19 positive cells were present in both brain hemispheres, and numerous GFAP positive astrocytes were found around the puncture lesion. CONCLUSIONS: Within the experimental conditions of the present research, C6 glioma did not demonstrate any relevant deviations concerning development, clinical symptomatology and macroscopic anatomy relative to those already described in the literature.

(E)-4-aryl-4-oxo-2-butenoic acid amides, chalcone-aroylacrylic acid chimeras: design, antiproliferative activity and inhibition of tubulin polymerization.

Antiproliferative activity of twenty-nine (E)-4-aryl-4-oxo-2-butenoic acid amides against three human tumor cell lines (HeLa, FemX, and K562) is reported. Compounds showed antiproliferative activity in one-digit micromolar to submicromolar concentrations. The most active derivatives toward all the cell lines tested bear alkyl substituents on the aroyl moiety of the molecules. Fourteen compounds showed tubulin assembly inhibition at concentrations <20 µM. The most potent inhibitor of tubulin assembly was unsubstituted compound 1, with IC50 = 2.9 µM. Compound 23 had an oral LD50in vivo of 45 mg/kg in mice. Cell cycle analysis on K562 cells showed that compounds 1, 2 and 23 caused accumulation of cells in the G2/M phase, but inhibition of microtubule polymerization is not the principal mode of action of the compounds. Nevertheless, they may be useful leads for the design of a new class of antitubulin agents.

Preliminary evaluation of the in vitro release and in vivo absorption in rabbits of the modified-release dosage forms.

OBJECTIVE: The suitability of the rabbit as an animal model for the primary screening and selection of the pilot scale batches during the early stages of the formulation development was studied. MATERIALS AND METHODS: Three modified-release formulations of aminophylline consisted of Carbopol® 971P/HPMC K4M (F-I), and HPMC K100M (F-II) or HPMC K4M (F-III) were used. Commercial products were Aminofilin retard 350 mg tablets, Srbolek, Serbia (R-I) and Phyllocontin(®) 350, tablets Purdue Frederic, Canada (R-II). RESULTS: Calculated release rate constants and the ƒ2 values between R-I/F-I (84.1) and R-II/F-III (83.4) indicated similar in vitro release while the coefficient n showed presence of different mechanisms of release from Anomalous transport, Fickian diffusion to Case-II transport. Higher Tmax, was found in the rabbits, dosed with F-II (12.00 h), F-III (10.50 h), and R-II (15.00 h) formulation. The highest Cmax (9.22 mg/L) was obtained with F-II, similar lower values was seen for F-I and F-III, while commercial products showed the lowest values R-I (5.58 mg/L) and R-II (4.18 mg/L). Higher AUC values were detected for all three formulations (from 115.90 to 204.06 mgh/L) in relation to commercial products (105.33 and 113.25 mgh/L). DISCUSSION AND CONCLUSION: The results demonstrated a good correlation of Level A (r(2) = 0.97) for the two formulations (F-I, F-III) and commercial product (R-I) indicates that there is a reasonable assumption that the rabbit might be use as a model for the preliminary comparison of scale up formulations in the early stages of the product development.

Different K+ channels are involved in relaxation of arterial and venous graft induced by nicorandil.

The drug nicorandil is a vasodilator approved for the treatment of angina. In addition to its well-known effect on the opening of ATP-sensitive K (KATP) channels, nicorandil-induced vasorelaxation also involves the opening of Ca-activated K channels. The aim of this study was to investigate the effects of nicorandil on the isolated human internal mammary artery (HIMA) and the human saphenous vein (HSV) and to define the contribution of different K channel subtypes in the nicorandil action on these arterial and venous grafts. Our results show that nicorandil induced a concentration-dependent relaxation of HSV and HIMA rings precontracted by phenylephrine. Glibenclamide, a selective KATP channels inhibitor, partially inhibited the response to nicorandil in both HSV and HIMA. Iberiotoxin, a most selective blocker of large-conductance Ca-activated K (BKCa) channels, partly antagonized relaxation of HIMA. A nonselective blocker of voltage-gated K channels, 4-aminopyridine caused partial inhibition of the nicorandil-induced relaxation of HSV but did not antagonize relaxation of HIMA induced by nicorandil. Margatoxin, a potent inhibitor of KV1.3 channels, did not abolish the effect of nicorandil on HSV and HIMA. Our results showed that nicorandil induced strong endothelium-independent relaxation of HSV and HIMA contracted by phenylephrine. It seems that KATP and 4-aminopyridine-sensitive K channels located in the smooth muscle of HSV mediated relaxation induced by nicorandil. In addition, KATP and BKCa channels are probably involved in the nicorandil action on HIMA.

Strawberry polyphenols attenuate ethanol-induced gastric lesions in rats by activation of antioxidant enzymes and attenuation of MDA increase.

BACKGROUND AND AIM: Free radicals are implicated in the aetiology of gastrointestinal disorders such as gastric ulcer, colorectal cancer and inflammatory bowel disease. Strawberries are common and important fruit due to their high content of essential nutrient and beneficial phytochemicals which seem to have relevant biological activity on human health. In the present study we investigated the antioxidant and protective effects of three strawberry extracts against ethanol-induced gastric mucosa damage in an experimental in vivo model and to test whether strawberry extracts affect antioxidant enzyme activities in gastric mucosa. METHODS/PRINCIPAL FINDINGS: Strawberry extracts were obtained from Adria, Sveva and Alba cultivars. Total antioxidant capacity and radical scavenging capacity were performed by TEAC, ORAC and electron paramagnetic resonance assays. Identification and quantification of anthocyanins was carried out by HPLC-DAD-MS analyses. Different groups of animals received 40 mg/day/kg body weight of strawberry crude extracts for 10 days. Gastric damage was induced by ethanol. The ulcer index was calculated together with the determination of catalase and SOD activities and MDA contents. Strawberry extracts are rich in anthocyanins and present important antioxidant capacity. Ethanol caused severe gastric damage and strawberry consumption protected against its deleterious role. Antioxidant enzyme activities increased significantly after strawberry extract intake and a concomitantly decrease in gastric lipid peroxidation was found. A significant correlation between total anthocyanin content and percent of inhibition of ulcer index was also found. CONCLUSIONS: Strawberry extracts prevented exogenous ethanol-induced damage to rats' gastric mucosa. These effects seem to be associated with the antioxidant activity and phenolic content in the extract as well as with the capacity of promoting the action of antioxidant enzymes. A diet rich in strawberries might exert a beneficial effect in the prevention of gastric diseases related to generation of reactive oxygen species.

Screening of chronic diseases and chronic disease risk factors in two rural communities in Kosovo.

BACKGROUND: A cross-sectional study was carried out in Velika Hoca and Orahovac, two rural communities in Kosovo and Metohia, with the aim of assessing the prevalence of chronic diseases and associated risk factors. METHODS: The study involved 423 (180 male) adult inhabitants aged 51 +/- 16 years and included an interview, medical documentation, physical, ultrasound, laboratory examinations and ECG. RESULTS: Hyperlipidemia was the most frequent (70%) risk factor followed by alcohol consumption (47%), hypertension (42%), smoking (36%) and obesity (32%). Ischemic heart disease was diagnosed in 25 patients, hypertensive cardiomyopathy in 17, other cardiomyopathies in 5 and arrhythmia in 20 patients. Nine persons had chronic obstructive pulmonary disease. Previously diagnosed liver cirrhosis occurred in 5 and chronic hepatitis in 8 subjects, while liver steatosis with elevated serum transaminases (22 persons), elevated transaminases with normal ultrasound (20 persons), tumor or suspected tumor (7 persons) were detected in the survey. Gastrointestinal symptoms were the most prevalent but peptic ulcer and gastritis had been previously diagnosed in 64 and 47 patients. Kidney and urinary tract diseases were known for 52 patients (12 with chronic renal failure and 4 on hemodialysis) and 46 more were detected in the study. Among them in 22 patients with markers of kidney disease and unclear diagnosis 12 had a positive family history, 8 low-grade proteinuria, 14 tubular dysfunctions and 7 eGFR (estimated glomerular filtration rate) below 60 ml/min/1.73 m2. CONCLUSION: In the Serbian enclave of Velika HoEa and Orahovac the prevalence of cardiovascular diseases was similar to that of gastrointestinal, liver and kidney diseases. This differs from other parts of Serbia where cardiovascular disorders are the leading cause of disease burden.

High prevalence of kidney disease in two rural communities in Kosovo and Metohia.

A systematic survey was carried out in an enclave in Kosovo and Metohia, with the aim of assessing the prevalence of kidney diseases. The survey involved 423 (180 males) adult inhabitants from two small settlements, Velika Hoca and Orahovac, and included an interview, medical documentation, physical, ultrasound, and laboratory examinations. Persons with any detected disorder indicating kidney disease were invited for additional examination of kidney function. Using urine dipstick test, proteinuria was detected in 19.1% and hemoglobinuria in 4.5% of the examined subjects. Glomerular filtration rate (Modification of Diet in Renal Disease (MDRD) formula) below 60 mL/min/1.73 m(2) was found in 5.2% of subjects. Kidney ultrasound examination detected reduced length of right and left kidneys in 38 and 24 persons, respectively. Cysts were also a frequent finding, but polycystic kidney, hydronephrosis, and kidney stones were found in about 2% each. The analysis of data obtained by the present examination and available medical documentation revealed kidney and urinary tract diseases in 98 persons: 52 patients with already known disease and 46 patients detected in the survey. Out of them in 22 patients diagnosis of kidney disease could not be established during the survey but laboratory analyses indicated that they might suffer from tubulointerstitial disease: 14 had tubular dysfunctions, 8 of them low-grade proteinuria, and 12 had a positive family history for kidney disease. In the enclave of Velika Hoca and Orahovac the prevalence of kidney disease was 7.0% indicating that these communities might be placed among those with a high prevalence of kidney disease in Serbia.

Attenuation of cold restraint stress-induced gastric lesions by an olive leaf extract.

Olive leaf extract (OLE) possesses, among other, antioxidative properties, but whether it influences gastroprotection against stress-induced gastric lesions remains unknown. In this study we investigated the protective effect of OLE, a natural antioxidant, on gastric mucosal damage induced by cold restraint stress (CRS) in rats. Three different doses of commercial OLE EFLA((R)) 943 were applied intragastrically (i.g.) 30 min prior to stress induction. Macroscopic gastric lesions were evaluated and ulcer index (UI) was calculated. Histological evidence of gastric mucosal lesions was also obtained. Concentration of malondialdehyde (MDA) as an index of lipid peroxidation, and catalase (CAT) and superoxide dismutase (SOD) activities were determined in gastric mucosa. The effects of applied OLE on gastric mucosal lesions, lipid peroxidation and antioxidative enzymes activity were compared with effects of i.g. pretreatment of reference drug, ranitidine. CRS caused severe gastric lesions in all non-pretreated animals, and this finding was confirmed histologicaly. Pretreatment with OLE (40, 80 and 120 mg.kg(-1)), as well as with ranitidine (50 mg.kg(-1)), significantly (p < 0.001) attenuated stress-induced gastric lesions. Treatment with 80 mg.kg(-1) of OLE was the most effective in prevention of rise in gastric MDA level and decrease in CAT and SOD activity. The results obtained indicate that OLE possesses gastroprotective activity against CRS-induced gastric lesions in rats, possibly related to its antioxidative properties.

The effects of tiazofurin on basal and amphetamine-induced motor activity in rats.

The effects of tiazofurin (TR; 2-beta-d-ribofuranosylthiazole-4-carboxamide), a purine nucleoside analogue on basal and amphetamine (AMPH)-induced locomotor and stereotypic activity of adult Wistar rat males were studied. The animals were injected with low (3.75, 7.5, and 15 mg/kg ip) and high (62.5, 125, and 250 mg/kg ip) TR doses. Neither low nor high TR doses influenced basal locomotor and stereotypic activity in comparison with the corresponding controls treated with saline only. However, pretreatment with TR at any dose applied, except for the lowest one, significantly decreased AMPH-induced (1.5 mg/kg ip) locomotor activity, while AMPH-induced stereotypic activity was inhibited with the two highest TR doses. In addition, TR was detected in the brain by HPLC already 15 min after the injection (125 mg/kg ip) to reach a maximum 2 h after the administration and was detectable in this tissue during the next 4 h. Our results indicate that TR modifies central regulation of the motor activity, possibly by influencing dopaminergic (DA-ergic) transmission.

HPLC determination of tiazofurin in the rat brain.

A sensitive, selective and reproducible HPLC method for determination of tiazofurin in rat brain was developed and validated. The method allowed determination and quantification of nanomolar concentrations of tiazofurin in brain and its regions (hippocampus, cortex and striatum) of treated animals. Separation of tiazofurin from other peaks from brain tissue was achieved by isocratic elution on reverse phase chromatographic column. The mobile phase consisted of 0.05 M sodium acetate pH 4.6. Run time was 15 min.

Simultaneous LC determination of tiazofurin, its acetyl and benzoyl esters and their active metabolite thiazole-4-carboxamide adenine dinucleotide in biological samples.

A rapid and sensitive HPLC-RP method for simultaneous determination of tiazofurin, its 5'-O acetyl and benzoyl esters and their active metabolite thiazole-4-carboxamide adenine dinucleotide was developed and validated. The method allowed determination and quantification of nanomolar quantities of these substances in cell extracts of treated cells, and was also used in kinetic studies of cellular uptake of tiazofurin and its esters from the cultivation medium. Separation of the analyzed substances from unidentified peaks from both biological materials was achieved by gradient elution, thus reducing the possibility of interference. The mobile phase consisted of a 0.1 M sodium-hydrogen phosphate, pH 5.1 and methanol. Run time was 22 min, with 5 min equilibration time.