Metabolites of ochratoxins in rat urine and in a culture of Aspergillus ochraceus.

We studied the metabolic profile of ochratoxin A (OA) in rats and in a culture of OA-producing Aspergillus ochraceus. Ochratoxin alpha (O alpha), ochratoxin beta (O beta), 4-R-hydroxyochratoxin A (4-R-OH OA), 4-R-hydroxyochratoxin B (4-R-OH OB), and 10-hydroxyochratoxin A (10-OH OA) were isolated from a culture of A. ochraceus and structurally characterized by 1H nuclear magnetic resonance spectroscopy, mass spectrometry and high-pressure liquid chromatography. 4-R-OH OA and O alpha were consistently produced and were the dominant biotransformed metabolites in the fungal culture and in rats treated with OA and ochratoxin C (OC), while the formation of 10-OH OA was conditional in the fungal system. Green fluorescent biomacromolecules were isolated by detergent extraction of the fungal culture followed by cold-acetone precipitation and gel filtration. Acid hydrolysis of the fluorescent macromolecules resulted in the release of several ochratoxins, including O alpha (80%), OA (2%), and OC (5%), and other unidentified fluorescent compounds but not OB and O beta. Cross-reactivity studies of the natural macromolecule conjugates of OA with anti-OA polyclonal antibodies indicated that they were covalently linked to the macromolecules via a group other than the carboxyl group. These studies demonstrated that a fungus can produce some of the same metabolites of OA as the rat and that O alpha, OA, and OC may be covalently linked to fungal macromolecules.     

Characterization of proteolytic systems in human and rat urine

Activities of proteolytic enzymes were detected in rat and human urine by using [125 l] iodo-insulin B chain as a substrate. The pH optimum of human urine activity was in the acidic range (pH 2.0) whereas the rat urine had two pH optima, one at the acidic range similar to human urine and another at pH 7.5. The activities were linear with time and amount of enzyme. Study with various proteinase inhibitors revealed that the acidic pH activities of human and rat urine were apparently of carboxyl endopeptidases since they were totally inhibited by pepstatin 10-8M. The neutral pH proteolysis of rat urine was inhibited by chelating agents and therefore it was considered as a metalloendopeptidase activity. These findings show the difference between the content of urinary proteolytic enzymes in humans and in rats by using a sensitive and simple radioactive assay.     

Tight junctions are sensitive to peptides eliminated in the urine

We prepare an extract of dog urine (DLU) that, when applied to monolayers of MDCK cells (epithelial, derived from a normal dog), enhances the transepithelial electrical resistance (TER) in a dose-dependent manner. This increase is not reflected in variations of the linear amount of TJ nor in changes of the pattern of junctional strands as observed in freeze fracture replicas, nor in the distribution of claudin 1 (a membrane protein of the TJ) nor ZO-1 (a TJ-associated protein). A preliminary characterization of the active component of DLU indicates that it weighs 30-50 kDa, bears a net negative electric charge, and is destroyed by type I protease but not by 10-min boiling. DLUs prepared from human, dog, rabbit and cat are effective on MDCK cells. However, dog DLU increases TER in MDCK (dog) as well as LLCPK1 (pig) monolayers, but not in other epithelial cell lines such as LLCRK1 (rabbit), PTK2 (kangaroo) and MA-104 (monkey), nor in the endothelial cell line CPA47 (cow). Given that in its transit from the glomerulus to the urinary bladder the filtrate increases its concentration by more than two orders of magnitude, the substance(s) we report may act at increasingly higher concentrations in each segment, and afford a potential clue to the progressive increase of TER across the walls of the nephron from the proximal to the collecting duct.     

Method for detection of 2-azahypoxanthine in human and rat urine

A new, simple, reproducible, and quantitative method for the detection of 2-azahypoxanthine (2-AH) in urine is described. The method is based on removal of interfering substances from urine by cation- and anion-exchange chromatography. Quantitative determination of 2-AH eluted from the anion-exchange resin involves its conversion to 5-diazoimidazole-4-carboxylic acid and subsequent coupling of this compound with N-(1-naphthyl)ethylenediamine. The resultant dye product has an absorption maximum at 505 nm in 2.4 N HCl, which is linearly related to the original 2-AH concentration in the range of 0–8 μg/ml. The only substance found to interfere and not be removed or destroyed is p-acetamidophenyl glucuronide, an excretion product of phenacetin- and acetaminophen-containing drugs.     

Characterization of protein-bound gold in rat urine following aurothiomalate administration and of rat and human albumin-gold-thiomalate

The metabolites of gold in the urine of rats given the antiarthritic drug aurothiomalate were investigated by gel permeation chromatography, electrophoresis, and chemical studies. Following a single dose of aurtothiomalate, the excreted gold was protein-bound in the high-molecular-weight (greater than or equal to 150,000 dalton) and serum albumin fractions. Electrophoresis confirmed the presence of albumin, but showed that the other proteins present differ from those in normal or in vitro aurothiomalate-incubated rat sera. The pattern of the proteins establishes that the proteinuria was of the glomerular type. The alterations in the gold distribution produced by incubation of the urine with the low-molecular-weight thiol penicillamine and with exogenously added aurothiomalate indicated the existence of a labile equilibrium of gold among protein binding sites in the urine. Incubation of rat and human sera and commercially prepared serum albumins with aurothiomalate increased the electrophoretic mobility of the albumin. The significance of this change in electrophoretic mobility with respect to two models of gold binding by serum albumin is discussed.     

Pharmacological properties of a potent neuroleptic drug octoclothepin

Octoclothepin, 8-chloro-1-(4-methylpiperazino)-10,11-dihydrodibenzo (b,f) thiepin, is a very potent neuroleptic drug with pronounced central antidopaminergic and antiserotonin actions. In most animal experiments, its plharmacological profile resembles that of perphenazine. Octoclothepin reveals an intensive central depressant action in a series of observational and instrumental procedures in rodents. Its active oral doses are within the range of 0.54 to 2.2 mg kg-1 in mice and of 0.1 to 4.8 mg kg-1 in rats. Octoclothepin possesses high cataleptogenic and anti-apomorphine activities in rats; it is able to exert full protection against apomorphine-induced emesis in dogs after the dose of 0.1 mg kg-1 s.c. Octoclothepin reduces some actions and toxicity of d,l-amphetamine and phenmetrazine in rodents. In the rat corpus striatum, octoclothepin in doses of 0.5 and d1.5 mg kg-1 s.c. reduces the DA level and raises the HVA and DOPAC levels significantly. Octoclothepin has antihistamine, antiserotonin and antianaphylactoid actions, it exhibits a high protection against the lethal action of adrenaline and noradrenaline in mice and rats, respectively. Acute toxicological data in mice, rats, rabbits and dogs are given. Clinical antipsychotic effectiveness of octoclothepin has been verified in a large population of psychiatric patients.     

Glycoasparaginase in human urine

Glycoasparaginase was purified 15 000-fold from human urine. The enzyme is a tetrameric protein of 86 kDa, composed of two heavy chains (25 kDa) and two light chains (18 kDa). Its structure and properties are very similar to those of human leukocyte glycoasparaginase. Glycoasparaginase activity is totally absent from urine of aspartyl-glycosaminuria patients.     

Histidinoalanine in human urine

Histidinoalanine, a cross-linking component of connective tissue proteins, was detected in the acid hydrolysate of human urine. The concentrations in urines from newborn babies, children, and adults were 1.33 +/- 0.27, 0.77 +/- 0.23, and 0.89 +/- 0.33 nmol/mg creatinine, respectively. Possible origins of urinary histidinoalanine are discussed.