Apparent inhibition of hepatic triacylglycerol secretion, independent of synthesis, in high-fat fish oil-fed rats: role for insulin.

Rats were fed Chow (C; low-fat control) or a purified high-fat (30% of calories) low cholesterol diet containing menhaden oil (MO), corn oil (CO) or lard (L) for 2, 4 or 6 weeks. Rats were killed after an overnight fast. MO-fed rats had a larger weight/body weight that was accompanied by a lower mg liver DNA/g liver but unchanged liver DNA/body weight, indicating that hepatomegaly in the MO-fed rats was due to cellular hypertrophy. MO-feeding prevented the rise in plasma triacylglycerol and cholesterol observed with the other high-fat diets. There was a marked progressive accumulation of total liver triacylglycerol in the MO- and CO-fed rats. Plasma insulin was reduced in the MO-fed rats relative to all other groups. There were strong positive relationships between plasma insulin and triacylglycerol and between insulin and cholesterol in the high-fat-fed rats. Total liver glucose-6-phosphate dehydrogenase and malic enzyme activities were reduced by MO-feeding and were directly correlated with plasma cholesterol and insulin. These data are consistent with an apparent inhibition of hepatic triacylglycerol secretion by high-fat fish oil-feeding that is independent of the inhibitory effects on triacylglycerol synthesis. These data suggest a role for insulin in regulating the plasma triacylglycerol and cholesterol concentrations in MO-fed rats.

Dopamine D2 synthesis-modulating receptors are present in the striatum of the guinea pig.

Dopamine and selective agonists of D1 [(1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrochloride, SKF 38393] and D2 [(3-[2-[N-(3-hydroxyphenylethyl)-N-propylamino]ethyl] phenol, RU 24926] receptors were examined as inhibitors of the activity of tyrosine hydroxylase in the striatum of the guinea pig. In soluble enzyme preparations, the agonists were weak inhibitors of the activity of tyrosine hydroxylase. However, the catechol-containing agonists dopamine (EC50 = 44.7 microM) and SKF 38393 (EC50 = 35.5 microM) were more potent than the non-catechol agonist RU 24926 (EC50 = 447 microM). All of the agonists were much more potent in synaptosome-rich preparations of guinea pig striatum, where stimulation of autoreceptors mediated inhibition of the enzyme (SKF 38393, D1, EC50 = 27 nM; RU 24926, D2, EC50 = 30 nM; dopamine, non-selective, EC50 = 1.5 microM). The D1 antagonist, SCH 23390 [(R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-(1H)-3- benzazepine hydrochloride], did not significantly reduce the action of SKF 38393 or dopamine. Furthermore, the D2 antagonist, (-)-sulpiride, significantly antagonized the inhibitory activity of both RU 24926 and dopamine. Studies in synaptosome-rich preparations from the striatum of the rat showed that both SKF 38393 (EC50 = 398 nM) and RU 24926 (EC50 = 58 nM) were also effective autoreceptor-mediated inhibitors of the activity of tyrosine hydroxylase in the rat. However, in the rat, SCH 23390 and (-)-sulpiride were equally effective in attenuating the inhibitory actions of dopamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of young barley leaf extract and antioxidative vitamins on LDL oxidation and free radical scavenging activities in type 2 diabetes.

BACKGROUND: The effects of supplementation of young barley leaf extract (BL) and/or antioxidative vitamins C and E on different low-density lipoprotein (LDL) subfractions susceptibility to oxidation and free radical scavenging activities in patients with type 2 diabetes were evaluated. METHODS: Thirty-six type 2 diabetic patients were enrolled in this study. The subjects received one of the following supplements daily for 4 weeks: 15 g BL, 200 mg vitamin C and 200 mg vitamin E (CE), or BL plus CE (BL + CE). RESULTS: The lucigenin-chemiluminescence (CL) and luminol-CL levels in blood were significantly reduced in all groups. Vitamin E content of LDL subfractions increased significantly following supplements, especially for BL + CE group. The percent increase of lag times in the BL + CE was significantly higher than those in the BL or CE group. The antioxidative effect of BL + CE was the greatest for small, dense LDL (Sd-LDL) with further increases in percentage of lag times 4 folds compared to BL alone. CONCLUSION: Our results indicate that supplementation with BL may help to scavenge oxygen free radicals, save the LDL-vitamin E content, and inhibit LDL oxidation. Furthermore, the addition of vitamins C and E to BL can inhibit the Sd-LDL oxidation more effectively, which may protect against vascular diseases in type 2 diabetic patients.

Improved agar diffusion method for detecting residual antimicrobial agents.

The improved agar diffusion method for determination of residual antimicrobial agents was investigated, and the sensitivities of various combinations of test organisms and assay media were determined using 7 organisms, 5 media, and 31 antimicrobial agents. Bacillus stearothermophilus and synthetic assay medium (SAM) showed the greatest sensitivity for screening penicillins (penicillin G and ampicillin). The combination of Bacillus subtilis and minimum medium (MM) was the most sensitive for tetracyclines (oxytetracycline and chlortetracycline), B. stearothermophilus and SAM or Micrococcus luteus and Mueller-Hinton agar (MHA) for detecting tylosin and erythromycin, B. subtilis and MHA for aminoglycosides (streptomycin, kanamycin, gentamicin, and dihydrostreptomycin), B. stearothermophilus and SAM for polyethers (salinomycin and lasalocid), and B. subtilis and MM or Clostridium perfringens and GAM for polypeptides (thiopeptin, enramycin, virginiamycin, and bacitracin). However, gram-negative bacterium Escherichia coli ATCC 27166 and MM were better for screening for colistin and polymixin-B. For detecting the synthetic drugs tested, the best combination was B. subtilis and MM for sulfonamides, E. coli 27166 and MM for quinolones (oxolinic acid and nalidixic acid), B. subtilis and MM for furans (furazolidone), and the bioluminescent bacterium Photobacterium phosphoreum and luminescence assay medium for chloramphenicol and oxolinic acid. The results showed that the use of four assay plates, B. stearothermophilus and SAM, B. subtilis and MM, M. luteus and MHA, and E. coli 27166 and MM, was superior to the currently available techniques for screening for residual antimicrobial agents in edible animal tissues.

Simple continuous and simultaneous determination of tetracycline residues.

A new continuous separation method was developed for the determination of five different tetracyclines (oxytetracycline, tetracycline, chlortetracycline, methacycline and doxycycline). A bioassay using minimum medium (MM) seeded with Bacillus subtilis ATCC 6633 was carried out for the detection, with simple extraction from the agar block of the clear inhibition zone on the MM produced by the mixed tetracyclines. The extract was subjected to continuous identification by high performance liquid chromatography using a mu-Bondapack C18 column. The tetracyclines were separated at ambient temperature using a mobile phase of 0.01 M oxalic acid: acetonitrile: N,N-dimethylformamide (74:18:8, v/v/v) at a flow rate of 1.0 ml min-1. A variable-wavelength detector set at 355 nm and recorder set at 4 mm min-1 were used for the detection. The entire mixture was resolved as five peaks with retention times ranging from 2.75 to 9.65 minutes. This continuous, simple and rapid method of detection, extraction and identification may be useful for routine laboratory testing of residual antimicrobial agents in food.

Liquid chromatographic determination of fluorescent derivatives of six sulfonamides in bovine serum and milk.

A rapid and sensitive liquid chromatographic (LC) method with fluorometric detection was developed to detect sulfadiazine, sulfathiazole, sulfamethazine, sulfamonomethoxine, sulfamethoxazole, and sulfadimethoxine residues in bovine serum and milk. p-Aminobenzoic acid (PABA) was added as an internal standard. The sulfonamides were extracted from samples and derivatized with fluorescamine, and 50 microL was injected into a NovaPak C18 LC column and eluted with acetonitrile-10 mM potassium phosphate (30 + 70, v/v). The sulfonamides were detected fluorometrically (excitation, 390 nm; emission, 475 nm), and their retention times ranged from 6.2 to 16.5 min without interference from coextractives. The detection limit for standard sulfonamide solution was 0.1 ng/mL; the calibration curves were linear between 1 and 100 ng/mL in the presence of PABA as internal standard. Recovery rates of sulfonamides from spiked samples (1 and 10 ppb) were 95.4-107.2 and 81.4-89.6% for serum and 80.7-91.1 and 62.6-84.1% for milk, respectively.

Kenny syndrome: case report and literature review.

A 34-month-old girl presented with a clinical picture of Kenny syndrome. The clinical manisfestations included growth retardation, persistent open anterior fontanelle, prominent forehead, mid-facial dysplasia, hypocalcemic tetany and characteristic radiologic skeletal abnormalities. Serum levels of immunoreactive parathyroid hormone (PTH) remained inappropriately low during hypocalcemic episodes in the neonatal period; indicating that hypocalcemia was a consequence of the hypoparathyroid state. This is the first reported case of Kenny syndrome in Taiwan. The literature on the pathogenesis, etiology and genetic basis of this disorder is reviewed in this paper.

Persistent pulmonary hypertension of the newborn associated with excessive pulmonary arterial muscularization: report of an autopsy case.

A 3700-g male infant born at 37 weeks' gestation presented with cyanosis at birth. He was diagnosed as having persistent pulmonary hypertension of the newborn (PPHN) on the basis of persistent hypoxemia, despite continuous mechanical ventilatory support with 100% O2, and right-to-left shunting through the foramen ovale shown by Doppler echocardiography. Treatment with hyperventilation, and administration of tolazoline, prostaglandin E1 and MgSO4 failed to reverse his hypoxemia. High ventilator settings were required, and pneumothoraces ensued. Airway resistance increased gradually with development of hypercapnia and deterioration of hypoxemia. Bradycardia unresponsive to resuscitation occurred, and he died at eight days of age. Postmortem examination of the lungs revealed increased peripheral connective tissue and diffuse extension of medial smooth muscle to the precapillary pulmonary arteries. Excessive antenatal muscularization of the peripheral pulmonary arteries and resultant increased vasoconstriction capacity may have played an important role in the pathogenesis of PPHN in this case.

Simultaneous identification and determination of residual penicillins by use of high-performance liquid chromatography with spectrophotometric or fluorometric detectors.

Using 7 penicillins (amoxicillin, ampicillin, methicillin, penicillin G, oxacillin, cloxacillin, and dicloxacillin), simultaneous and direct determination of residual penicillins in biological samples was carried out by use of bioassay and high-performance liquid chromatography with spectrophotometric or fluorometric detectors. By use of assay medium seeded with penicillin-sensitive Micrococcus luteus (ATCC No. 9341) as a test organism, we were able to detect penicillins even at low concentrations. All penicillins treated with 10 U of penicillinase/ml did not produce inhibition zones by disk testing, even at a concentration of 100 micrograms of penicillin/ml/assay plate. Using a mobile phase of acetonitrile:methanol: 0.01M KH2PO4 (19:11:70, v/v/v; pH, 7.1), standard solutions of the penicillins were separated from each other by use of high-performance liquid chromatography analysis, producing symmetric peaks without tailing, each of which had a characteristic retention time. Simultaneous detection of residual penicillins in bovine serum, kidneys, and liver, for the 5 penicillins for which analysis was possible by use of the UV method, yielded recovery rates from 71.4 to 102.3%; for the 2 amino-penicillins, amoxicillin and ampicillin, which could only be detected by use of the fluorometric method, recovery rate ranged from 72.9 to 103%.

Determination of sulfamethazine residue in chicken serum and egg by high-performance liquid chromatography with chemiluminescence detection.

A sensitive method that involves high-performance liquid chromatography with chemiluminescence detection is developed for the determination of sulfamethazine residue in samples of chicken serum and egg. Sulfamethazine is extracted from the samples and derivatized with fluorescamine. The derivatized samples are eluted by reversed-phase chromatography using a mixture of 10 mM potassium phosphate and 30% acetonitrile on a Nova-Pak C18 column. The post-column reagents in the chemiluminescence system are 1 mM bis[2-(3,6,9-trioxadecanyloxycarbonyl)-4-nitrophenyl] oxalate and 0.3M hydrogen peroxide in acetonitrile. The detection limit in the standard solution is 1 ng/mL, and the calibration curve is linear between 1 and 100 ng/mL. The recoveries of spiked samples (50 ppb) are 95.8 +/- 9.7% in chicken serum samples and 84.9 +/- 10.7% in egg samples. In actual sample analysis, the lowest detectable concentration of sulfamethazine (0.073 microgram/mL) was found at 48 h in serum and on day 9 (0.017 microgram/g) in egg after oral administration of a dose of 100 mg/kg body weight to hens.

Liquid chromatographic determination of salbutamol and clenbuterol residues in swine serum and muscle.

A simple and rapid method has been developed for determination of residual clenbuterol and salbutamol in swine serum and muscle using high-performance liquid chromatography. In a Nova-pak C18 column, the drug peaks were separated by a gradient using two mobile phases [acetonitrile:water (15:85, v/v) and acetonitrile:water (30:70, v/v)] for salbutamol and clenbuterol, respectively. A photodiode array set at 196 nm for salbutamol and 210 nm for clenbuterol, -0.01 to +0.2 AU, ambient temperature and flow rate of 1.0 ml/min, were used. The retention times were 5.4 and 21 min for salbutamol and clenbuterol, respectively. The detection limits for this method were 0.1 and 0.2 microliter/ml for salbutamol and clenbuterol, respectively. Average recoveries (0.1, 0.25, 0.5, 1.0 ppm spiked level) were 86.7 +/- 1.7% for salbutamol; 80.0 +/- 2.0% for clenbuterol spiked in serum; 64.2 +/- 8.9% for salbutamol; 62.9 +/- 4.2% for clenbuterol spiked in the muscle, respectively. The minimum detectable amount was 0.1 ppm, based on a spiked sample extract.

Determination of pyridonecarboxylic acids in plasma by reverse-phase high-performance liquid chromatography.

A simple qualitative and quantitative determination for pyridonecarboxylic acids including nalidixic acid (NA), oxolinic acid (OA) and pipemidic acid (PPA) in chicken plasma was carried out by microbiological, spectrophotometric, thin-layer chromatographic (TLC) and reverse-phase high-performance liquid chromatographic (HPLC) methods. As a test organism for bacteriological bioassay, Bacillus subtilis ATCC-6633 was the most sensitive of seven organisms investigated. Using the cup and the disc methods, a standard curve was obtained by determining the relationship between various drug concentrations and the diameter of the inhibition zone. The three drugs had two strong UV absorbance wavelengths (257 and 330 nm) on spectrophotometry. TLC analysis using a silica gel 60 F254 plate was investigated, and a solution of methanol:chloroform:acetic acid (3:1:1, v/v/v) was found to be the most suitable solvent for separation. The minimum concentration of drug detectable by this method was 0.5 microgram/ml for NA, 0.075 microgram/ml for OA and 0.39 microgram/ml for PPA. For HPLC analysis, a solution of acetonitrile:0.2 M phosphoric acid (1:1, v/v) was superior, and simultaneous determination of all three drugs was possible under the HPLC conditions used. The lowest measurable amount of drug in chicken plasma was 0.01 microgram/g. Recovery from extracts spiked with each drug at a known concentration was close to 100% for NA and OA, but only about 50% for PPA.

A reverse-phase high-performance liquid chromatographic determination of nicarbazin residues in eggs.

A reverse-phase high-performance liquid chromatographic (HPLC) method was employed for analysis of nicarbazin [1:1 mixture of 4,4'-dinitrocarbanilide (DNC) and 2-hydroxy-4, 6-dimethyl-pyrimidine] in chicken eggs. Nicarbazin residues were analysed by determining the DNC of nicarbazin. HPLC of the DNC portion of nicarbazin was performed with a reverse-phase mu-Bondapak C18 column, using a mobile phase of acetonitrile-water (7:3, v/v). A variable-wavelength detector set at 340 nm, 0.02 AUFS, and a recorder set at 4 mm/min were used for the detection. The standard curve for nicarbazin was linear within the range 0.05-2.0 micrograms/ml. The recovery of nicarbazin added to eggs was 90.2%. The detection limit of nicarbazin in this analytical method was 0.005 micrograms/ml. Nicarbazin was detected in 10% of eggs obtained by feeding chickens with a diet contaminated with nicarbazin within the range 0.07 to 1.39 micrograms/g, but it was not detected in eggs obtained commercially.

Serotonin 5-HT1A receptors mediate inhibition of tyrosine hydroxylation in rat striatum.

The role of serotonin (5-HT)1A heteroreceptors as modulators of dopamine synthesis was investigated by using in vitro and in vivo methods. In vitro studies were conducted utilizing either synaptosome-rich preparations of rat striatal tyrosine hydroxylase or soluble preparations of rat striatal tyrosine hydroxylase enzyme. 5-HT1A receptor modulation of tyrosine hydroxylation in vitro was estimated by using a radiometric, coupled enzyme assay. For in vivo investigations of the modulation of tyrosine hydroxylation, striatal dopa accumulation was measured (high-performance liquid chromatography-electrochemical detection) after administration of the aromatic amino acid decarboxylase inhibitor NSD-1015 (3-hydroxybenzylhydrazine). Both serotonin and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a selective 5-HT1A receptor agonist, were moderately potent, receptor-mediated inhibitors of tyrosine hydroxylation in synaptosomes, with EC50 values of 8.4 and 7.0 microM, respectively. The inhibitory activity of 8-OH-DPAT was attenuated by 5-HT1A-selective antagonists [10 microM propranolol, 10 microM (-)-alprenolol, 10 microM NAN-190 (1-(2-methoxyphenyl)-4-[4-(2-pthalimido)butyl] piperazine hydrobromide) and 10 microM pindolol] but not by a beta adrenoceptor antagonist devoid of activity at the 5-HT1A receptor (10 microM atenolol) or by a D2-dopamine-selective receptor antagonist [10 microM (-)-sulpiride]. In vivo 8-OH-DPAT exhibited a biphasic dose-response curve for inhibition of tyrosine hydroxylation, significant inhibition (30%, P < .05) occurred at a dose of 0.3 mg/kg s.c. In vivo, the 5-HT1A-selective antagonist NAN-190 (1 or 3 mg/kg s.c.) caused dramatic 2- to 2.5-fold elevations of dopa accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

A continuous, simple and rapid method for the detection, extraction and identification of residual antibacterial agents in meat.

Most antibacterial agents produced larger inhibition zones and showed lower detectable concentrations on minimal medium (MM) seeded with Bacillus subtilis than on Mueller-Hinton medium. After simple extraction, using a small amount of acetonitrile, from an agar block inside the inhibitory zone produced by each antibacterial agent, identification was carried out by reverse-phase high-performance liquid chromatography (HPLC). It is recommended that for inspection of residues MM is superior as a bioassay medium. The continuous, simple and rapid method described may be useful for routine laboratory testing of residual antimicrobial agents in food.