Malondialdehyde and antioxidant enzyme levels in the aqueous humor of rabbits in endotoxin-induced uveitis.

PURPOSE: To investigate the role of oxidative stress in endotoxin-induced uveitis. METHODS: Lipopolysaccharide was injected intravitreally into the right eyes of rabbits. Sterile saline was injected intravitreally into the left eyes as a control. Inflammation was assessed according to clinical score, aqueous humor cell count, and protein levels. Malondialdehyde, superoxide dismutase, glutathione peroxidase, catalase, and nitrite levels were measured in the aqueous humor. RESULTS: The clinical grade (p < 0.01), inflammatory cell count (p < 0.001), and protein content (p < 0.001) were significantly higher in the aqueous humor of eyes with uveitis than in that of controls. Malondialdehyde (p < 0.01) and nitrite (p < 0.001) levels in the aqueous humor of eyes with uveitis were significantly higher than in the control group. Superoxide dismutase (p < 0.001), glutathione peroxidase (p < 0.001), and catalase (p < 0.001) levels were significantly lower in the aqueous humor of eyes with uveitis than in that of the controls. CONCLUSIONS: Oxygen free radicals may be implicated as a mediator of inflammation in endotoxin-induced uveitis. The increase in free radicals in the aqueous humor may play a role in the pathogenesis of endotoxin-induced uveitis.

Decolorization of wastewater of a Baker's yeast plant by membrane processes.

The aim of this study is to develop a membrane-based treatment scheme to remove colorants from the effluent of a baker's yeast plant. For this purpose microfiltration (MF), ultrafiltration (UF) and nanofiltraton (NF) membranes with differing molecular weight cut-offs (MWCOs) were tested. To evaluate the effectiveness of membrane processes in treating the waste stream, optical density (OD), COD, color measurements together with permeation fluxes were used. Effects of pretreatment methods (coagulation and coarse filtration) and feed composition on OD, color, COD were studied. In addition, gel filtration analysis was employed to characterize feed and permeate streams in terms of MW distribution of organics that are present. Maximum rejections obtained were 94%, 89% and 72% for OD, color and COD, respectively, when 0.8 microm microfiltration membrane and 400 Da NF membrane were used in series. It was also observed that addition of intermediate UF steps did not increase overall rejections and final permeate flux of NF membrane. Based on these observations, an efficient scheme was offered.

Pharmacokinetics of morphine and its surrogates IV: Pharmacokinetics of heroin and its derived metabolites in dogs.

The pharmacokinetics of intravenously administered heroin and its derived metabolites, 6-O-monoacetylmorphine, morphine, and the glucuronidated conjugates of morphine, were studied in dogs at doses of 0.1-0.5 mg/kg. The spontaneous hydrolysis of the sampled biological fluids was inhibited by tetraethyl pyrophosphate so that the heroin concentration at the times of sampling could be analyzed for the first time. Heroin is concomitantly rapidly metabolized and distributed among body tissues. Metabolic clearance of 2916 +/- 321 ml/min are largely extrahepatic and are sixfold greater than hepatic blood flow. Nevertheless, the terminal half-life of 60-90 min resembles that of morphine and is maintained by the rate-determining return of distributed heroin from esterase-free tissues. Normal renal clearances of 43 +/- 6 ml/min result in 1.6 +/- 0.2% of the dose being renally excreted unchanged. The large overall volume of distribution, 344 +/- 60 liters, is indicative of heroin's wide distribution and lipophilicity, which rapidly equilibrates heroin in the plasma with the cerebrospinal fluid. Heroin is concomitantly metabolized almost equally to 6-O-monoacetylmorphine and morphine. The monoacetylmorphine is metabolized concomitantly to morphine and glucuronide conjugates in a 4:3 ratio and exercises its own activity. Its time course is close to that of heroin, although the total clearance (2200 ml/min) and overall volumes of distribution (90-170 liters) were less. The integrated model of transformations and eliminations was constructed with concomitant metabolism of the heroin metabolite, 6-O-monoacetylmorphine, to morphine and glucuronide conjugates. The assumption that the glucuronide conjugates partition into the bile and systemic circulation in the same ratio as does the conjugate of the derived morphine metabolite gave pharmacokinetic parameters consistent with the morphine pharmacokinetics studied previously and provided excellent fits of the plasma level-time curves of all of the derived metabolites of heroin.

Pharmacokinetics of morphine and its surrogates II: methods of separation of stabilized heroin and its metabolites from hydrolyzing biological fluids and applications to protein binding and red blood cell partition studies.

The inhibition of the spontaneous hydrolysis of heroin in fresh dog plasma on blood (t1/2 = 8 min) is effected by 10 mg of sodium fluoride/ml (t1/2 = 40 min) and 35 microgram of tetraethyl pyrophosphate/ml (t1/2 = 415 min). Tetraethyl pyrophosphate is the inhibitor of choice and gives the same stability for heroin as in phosphate buffer. Aged plasma loses its enzymatic efficiency. Heroin in cerebrospinal fluid hydrolyzes at rates similar to those in buffer. Modified extraction procedures developed for enzyme-inhibited plasma at pH 4.5 have high extraction efficiencies (86--100%) and permit isolation of undergraded heroin from its metabolites. Separations of heroin and metabolites from enzyme-inhibited plasma were effected by described high-pressure liquid chromatographic systems and from TLC with elution of pertinent developed spots. Efficiencies of these TLC recoveries were 81 +/- 1% for heroin and 82 +/- 1% for morphine. Contrary to the literature, heroin has significant protein binding where 40% of that not bound to an ultrafiltration membrane is bound to dog plasma proteins. The apparent partition coefficient is 1.4 +/- 0.2 between red blood cells and plasma water, and it is 0.8 +/- 0.1 between red blood cells and dog plasma.

Pharmacokinetics of morphine and its surrogates I: comparisons of sensitive assays of morphine in biological fluids and application to morphine pharmacokinetics in the dog.

A sensitive isotope derivatization assay was developed to quantify morphine in biological fluids in the nanogram per milliliter range. Morphine, derivatized with 3H-dansyl chloride, was separated from the reaction products by TLC. The spots were scraped from the plate, and the eluted radioactivity was determined by liquid scintillation. The standard deviations of this morphine assay were +/- 18.6 ng/ml in 100 microliter of plasma and +/- 1.86 ng/ml in 1 ml of plasma. The GLC analysis of pentafluoropropionated morphine in the range of 0--5 ng of morphine/ml of plasma had a standard deviation of +/- 0.46 ng/ml when 1 ml of plasma was taken. Liquid scintillation spectrometric analysis of 14C-morphine had a sensitivity of 1.5 ng/ml of plasma at double the background. There were no significant differences among the liquid scintillation, electron-capture GLC, and radioisotpoe derivatization methods for morphine obtained from the plasma of a dog given 14.00 mg iv of morphine. Morphine conjugates were assayed as morphine after the acid hydrolysis of plasma and urine preextracted to remove unconjugated morphine, and the equivalence of various methods was demonstrated to monitor plasma and urine pharmacokinetics in a dog.