PubMed Health⌕ Search

Biomedical subjects

J F Sutra

Publications and source records attributed to J F Sutra.

51 records · Page 3Linked to original sources
PubMed1993

Disposition of prednisolone in the course of subclinical fascioliasis in sheep.

1. The in vivo disposition of prednisolone in sheep was studied before, during and after recovery from experimental hepatitis of parasitical origin (fascioliasis). 2. After i.v. administration, plasma clearance of prednisolone was increased from 0.93 +/- 0.13 l/kg per h before infection to 1.73 +/- 0.50 l/kg per h at week 21 post-infection. The steady state volume of distribution was increased from 0.45 +/- 0.08 l/kg during the control period to 1.26 +/- 0.44 l/kg at week 5 post-infection. 3. None of the prednisolone binding parameters (specific and non-specific sites) was modified, and the overall mean unbound fraction was 24%. 4. Urinary excretion of unchanged prednisolone was low and only a trace of 6 beta-hydroxy-prednisolone was identified.

Animals↗
PubMed1993

Ivermectin in goat plasma and milk after subcutaneous injection.

The pharmacokinetics and mammary excretion of ivermectin were determined in goats following a single sc administration (0.2 mg/kg). Kinetic analysis of plasma and milk levels was performed using a 1-compartment model. The maximum plasma concentration of 6.12 ng/ml occurred at 2.85 d; the half-life of 4.03 d was similar to the value in sheep (3.68 d). Ivermectin was detected in the milk at the first sampling time and thereafter for at least 25 d. Comparison of the milk and plasma data shows the parallel disposition of the drug in milk and plasma with a milk-plasma concentration ratio of 1.08 +/- 0.23. In conclusion, the persistence of the drug in plasma is reflected in the duration of the presence of ivermectin in milk.

Absorption↗
PubMed1990

Simultaneous measurement of prednisone, prednisolone and hydrocortisone in plasma by high performance liquid chromatography.

The authors describe a normal phase liquid chromatographic assay suitable for therapeutic monitoring of prednisone, prednisolone, hydrocortisone in human and animal plasma. The compounds were extracted into dichloromethane using flumethasone as internal standard. The separation was obtained by using a silica normal phase (5 mu) and a mobile phase of dichloromethane, methanol, acetic acid (95.6; 4; 0.4 v/v/v). The absorbance of the compounds was monitored at 254 nm with a sensitivity limit of 2 ng/ml for all the products. This method was applied to pharmacokinetic studies in animal and therapeutic monitoring in man.

Chromatography, High Pressure Liquid↗
PubMed1988

Comparison of the monoamine and catabolite content in the cat and rabbit carotid bodies.

The monoamine and catabolite contents of a large number of rabbit (n = 95) and cat (n = 32) carotid bodies (CBs) have been measured by high performance liquid chromatography with electrochemical detection (HPLC-ED). The dopamine (DA) content as well as that of its precursors tyrosine (TYR), dihydroxyphenylalanine (DOPA) and catabolites dihydroxyphenylacetic acid (DOPAC), homovanilic acid (HVA) were approximately equal in both species. The noradrenaline (NA) content was 10 times larger in the cat than in the rabbit CBs. Twenty-nine out of the 32 cat CBs contained more NA than DA while the reverse was true in 92 out of 95 rabbit CBs. In 11 cats the right CB was sympathectomized and its DA and NA contents were compared to those of intact contralateral organs.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

Fate of the catecholamine stores in the rabbit carotid body superfused in vitro.

In rabbit carotid bodies (CBs) superfused during 1-5 h, with an air-equilibrated medium containing no tyrosine (TYR), the dopamine (DA) content decreased by approximately 60% after 1 h and remained constant afterwards. TYR and 3,4-dihydroxyphenylacetic acid (DOPAC) decreased with the same time course. Noradrenaline (NA) content exhibited a biphasic decrease of lesser magnitude than that of DA. Superfusions with a TYR-containing medium did not prevent the reduction in DA and TYR. Large amounts of DA and DOPAC were recovered in the effluent during the first hour of superfusion but after 90 min the two substances had declined below the detection limits (i.e. 0.5 and 1 pmol/5 min, respectively). The DA efflux decreased exponentially during the first hour and was not altered by changing the oxygen partial pressure (PO2) of the medium. The DOPAC efflux declined after 40 min of superfusion and was modulated by PO2. The DA and the DOPAC effluxes were not suppressed by omitting calcium ions from the superfusing medium. In 4 cat CBs equal amounts of DA and NA were recovered from the effluent during the first hour of superfusion.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Changes in monoamine content of the rabbit carotid body following prolonged electrical stimulation of the carotid sinus nerve.

In the anaesthetized, paralysed and artificially ventilated rabbit the carotid sinus nerve (CSN) has been stimulated electrically for 6 h. At the end of the stimulation period, the carotid body (CB) has been removed, frozen and processed for measurement of the monoamines (MA) and of their catabolites with high-pressure liquid chromatography and electrochemical detection (HPLC-ECD). Results show a significant increase of dopamine (DA) and adrenaline (A) content and of all the metabolites. Besides an important augmentation of DA metabolism suggests that CSN efferent activity exerts some regulation on the MA content and turnover of the CB.

Animals↗
PubMed1987

Determination of ivermectin in milk by high performance liquid chromatography.

A sensitive and specific high performance liquid chromatographic technique is described for the determination of ivermectin in milk. Milk samples (1 ml) were extracted with organic solvent (iso-octane and acetonitrile) and then chromatographed using reversed phase system. Specificity of the assay was confirmed by the use of mass spectrometry. After an subcutaneous administration of ivermectin (0.2 mg/kg) in a cow, ivermectin was detected in milk for about three weeks and over this period milk and plasma concentration were of the same order of magnitude.

Animals↗
PubMed1986

Local release of monoamines in the gastrointestinal tract: an in vivo study in rabbits.

Dialysis fibers chronically implanted into the gastric submucosa of rabbits allowed us to collect an interstitial fluid (I.S.F.) dialysate in which biogenic amine concentrations were measured, and compared with those obtained from plasma and tissue samples. The results suggest that I.S.F. concentrations represent a good assessment of the local release of the amines by enteric nerves and/or paracrine cells, under basal conditions. The fact that acetylcholine and neostigmine, when perfused through the dialysis system, increased I.S.F. serotonin (5-HT) concentrations, supports a cholinergic modulation of the release of 5-HT within the gastrointestinal wall, and validates the dialysis method as a powerful tool to monitor, in vivo, dynamic changes in I.S.F. monoamine concentrations.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Monoamines and their catabolites in the rabbit carotid body. Effects of reserpine, sympathectomy and carotid sinus nerve section.

Monoamines and their metabolites have been measured by high performance liquid chromatography with electrochemical detection, in control rabbit carotid bodies and under several experimental conditions: 1) at different times (3 h, 6 h, 24 h, 48 h) after intravenous injection of reserpine (5 mg/kg); 2) 14 days after sympathectomy; 3) 14 days after section of the carotid sinus nerve. The results were analyzed with probability plotting methods. Dopamine was the most important monoamine in the carotid body (CB) and its variations were very large. It was almost entirely depleted by reserpinization without simultaneous increase in 3,4-dihydroxyphenylacetic acid. Sympathectomy increased dopamine content but did not change noradrenaline content. However data analysis suggested that noradrenaline might be compartmented in two pools: one with a large variance, located in the type I cells was increased after sympathectomy, the other, more constant, located in the sympathetic nerve endings was entirely depleted after sympathectomy. Section of the carotid sinus nerve increased dopamine and noradrenaline and quadrupled the serotonin content of the CB. It is proposed that carotid sinus and sympathetic innervations regulate the monoamine metabolism of the CB.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1984

On the significance of monoamines and their metabolites in the cerebrospinal fluid of the sheep.

Assays capable of concurrently measuring small quantities of noradrenaline, dopamine, serotonin, and several of their metabolites in cerebrospinal fluid (c.s.f.) were developed by the use of high performance liquid chromatography with electrochemical detection. For comparison, cortical subarachnoid, ventricular, cisternal and lumbar c.s.f. were obtained by puncture under barbiturate anaesthesia in sheep. Basal concentrations related to the adrenergic system, including methoxyhydroxyphenylglycol (MHPG), were similar in ventricular, cisternal and lumbar c.s.f., and those of the serotoninergic metabolites, 5-hydroxyindole-3-acetylacetic acid (5-HIAA), were similar in ventricular and cisternal c.s.f. High concentrations of the dopamine metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were found only in ventricular c.s.f. Monoamine metabolites in ventricular c.s.f. under basal conditions and after various experimental manipulations were then determined over periods of 3 months in two different breeds of sheep fitted chronically with cannulae in lateral ventricles. A dose-related accumulation of all the acidic monoamine metabolites was recorded during treatment with probenecid. The increase in 5-HIAA was linear after administration of increased doses of tryptophan and 5-hydroxytryptophan. The concentrations of dopamine, DOPAC and HVA in the ventricular c.s.f. reflected the response of the dopaminergic system to agents capable of crossing the blood-brain barrier. It is concluded that cerebral metabolism in conscious sheep could be indirectly approached by recording the concentration of end-products of dopamine metabolism in ventricular cerebrospinal fluid, obtained under conditions of minimal stress.

Animals↗
PubMedDate not supplied

Determination of selamectin in dog plasma by high performance liquid chromatography with automated solid phase extraction and fluorescence detection.

A method is described for the determination of selamectin in dog plasma, using High-Performance Liquid Chromatography (HPLC) with fluorescence detection (excitation and emission wavelengths fixed at 355 and 465 nm, respectively). The fluorescent derivative was obtained by condensation reaction with trifluoroacetic anhydride and N-methylimidazole. The method employs 1 mL plasma samples and gives linear calibration graphs (r = 0.999) over the concentration range studied (0.5-50 ng mL(-1)). Automatic solid phase extraction using the benchmate procedure was used for sample preparation. This method permits the determination of selamectin at levels as low as 0.1 ng mL(-1) and its suitability was demonstrated by a pharmacokinetic study on a dog receiving the therapeutic dose (Spot-on administration).

Animals↗
PubMedDate not supplied

Evidence for glucuronidation and sulfation of zeranol and metabolites (taleranol and zearalanone) by rat and pig hepatic subfractions.

Biochemical evidence is given of alpha-zearalanol (zeranol), zearalanone, and beta-zearalanol (taleranol) glucurono- and sulfoconjugation in the rat and pig. It is based on the use of liver microsomal and cytosolic fractions, incubation with labeled endogenous coupling substrates, i.e. UDP-glucuronic acid and sulfate, and HPLC profiling of the resulting incubates. It is proved that only monoconjugates are produced, while it is suggested that conjugation occurs on the aromatic ring. Whether it is the C-14 or C-16 hydroxyl group that is conjugated remains to be demonstrated. When comparing the metabolic profiles in vitro with those already obtained in pig plasma, it can be concluded that both glucurono- and sulfoconjugates are produced in vivo.

Animals↗
PubMedDate not supplied

The pharmacokinetics of moxidectin after oral and subcutaneous administration to sheep.

The pharmacokinetic parameters of moxidectin were determined in ten sheep following a single subcutaneous or oral drench at a dose of 0.2 mg.kg-1. The plasma kinetics were best fitted by a two-compartment model. Moxidectin was detected in the plasma at the first sampling time (1 h) and thereafter for at least 60 d. The AUC were similar after both treatments indicating the same bioavailability for the two routes of administration. The oral route was characterized by a higher Cmax value (28.07 ng.mL-1 than after subcutaneous injection (8.29 ng.mL-1 and by significantly faster absorption as indicated by Tmax of 0.22 d and 0.88 d for oral and subcutaneous administrations, respectively. The most striking result of this experiment was the longer mean residence time reported for the subcutaneous route, i.e. 16.80 d as compared to 12.55 d for the oral drench. This differences is in agreement with previous studies demonstrating the longer anthelmintic efficacy of the subcutaneous route in comparison with oral administration.

Administration, Oral↗