Comparison of the isolation rates and characteristics of Salmonella isolated from antibiotic-free and conventional chicken meat samples.

Salmonella contamination in chicken samples can cause major health problems in humans. However, not only the effects of antibiotic treatment during growth but also the impacts of the poultry slaughter line on the prevalence of Salmonellae in final chicken meat sold to consumers are unknown. In this study, we compared the isolation rates and antimicrobial resistance of Salmonellae among antibiotic-free, conventional, conventional Korean native retail chicken meat samples, and clonal divergence of Salmonella isolates by multilocus sequence typing. In addition, the distribution of extended-spectrum ß-lactamase (ESBL) genes in ESBL-producing Salmonella isolates was analyzed. A total of 72 retail chicken meat samples (n = 24 antibiotic-free broiler [AFB] chickens, n = 24 conventional broiler [CB] chickens, and n = 24 conventional Korean native [CK] chickens) was collected from local retail markets in Seoul, South Korea. The isolation rates of Salmonellae were 66.6% in AFB chickens, 45.8% in CB chickens, and 25% in CK chickens. By analyzing the minimum inhibitory concentrations of ß-lactam antibiotics with the disc-diffusion test, we found that 81.2% of Salmonella isolates from AFB chickens, 63.6% of isolates from CB chickens, and 50% of isolates from CK chickens were ESBL producers; all ESBL-positive isolates had the CTX-M-15 genotype. Interestingly, all ESBL-producing Salmonellae were revealed as ST16 by multilocus sequence typing and had the genetic platform of blaCTX-M gene (IS26-ISEcp1-blaCTX-M-15-IS903), which was first reported in Salmonellae around the world. The Salmonella ST33 strain (S. Hadar) isolated in this study has never been reported in South Korea. In conclusion, our findings showed that antibiotic-free retail chicken meat products were also largely contaminated with ESBL-producing Salmonellae and that their ESBL genes and genetic platforms were the same as those isolated from conventional retail chicken meat products.

Direct determination of verapamil in rat plasma by coupled column microbore-HPLC method.

This report describes an automated coupled column microbore-high-performance liquid chromatography (HPLC) with fluorescence detection for direct determination of verapamil in small volume of rat plasma. We used HPLC system consisting of three columns such as precolumn, intermediate and analytical column and six-port switching valve and injected small volume of rat plasma to the system without sample preparation. An aliquot of sample was directly injected into Capcell Pak MF Ph precolumn for clean-up and enrichment, 35 mm Capcell Pak C18, intermediate column for concentration of compounds and 250 mm Capcell Pak C18 analytical column for separation of compounds and two mobile phases are used as mobile phase A (50mM ammonium phosphate, pH 4.5) and B (50mM ammonium phosphate:acetonitrile=70:30 v/v). Analysis of verapamil and internal standard, propranolol was performed with direct injection of 10 microl of rat plasma to the system and were eluted at 22 and 12 min, respectively, at a mobile phase flow rate of 0.5 (mobile phase A) and 0.15 ml/min (mobile phase B). The peaks of verapamil and internal standard were good shapes and well separated from any interfering endogenous peaks during a total run time of 25 min. The calibration curve for verapamil showed good linearity (r(2)=0.9997) over the concentration range of 0.01-2.50 microg/ml. The mean RSD (%) values of intra-day (n=5) and inter-day (n=5) variability of verapamil ranged from 1.96 to 9.06 and 0.62 to 3.08%, respectively. The LOD and LOQ were 0.01 and 0.025 microg/ml, respectively, for verapamil using 10 microl of rat plasma. An automated coupled column microbore-HPLC method was successfully applied to a pharmacokinetic study after intravenous injection of 3mg/kg of verapamil to the normal and dimethylnitrosamine (DMN)-induced hepatofibrotic rats.

Urinary N-acetyl-beta-D-glucosaminidase and malondialdehyde as a markers of renal damage in burned patients.

This study was aimed to evaluate renal dysfunction during three weeks after the burn injuries in 12 patients admitted to the Hallym University Hankang Medical Center with flame burn injuries (total body surface area, 20-40%). Parameters assessed included 24-hr urine volume, blood urea nitrogen, serum creatinine, creatinine clearance, total urinary protein, urinary microalbumin, 24-hr urinary N-acetyl-beta-D-glucosaminidase (NAG) activity, and urinary malondialdehyde (MDA). Statistical analysis was performed using repeated measures ANOVA test. The 24-hr urine volume, creatinine clearance, and urinary protein significantly increased on day 3 post-burn and fell thereafter. The urine microalbumin excretion showed two peak levels on day 0 post-burn and day 3. The 24-hr urinary NAG activity significantly increased to its maximal level on day 7 post-burn and gradually fell thereafter. The urinary MDA progressively increased during 3 weeks after the burn injury. Despite recovery of general renal function through an intensive care of burn injury, renal tubular damage and lipid peroxidation of the renal tissue suggested to persist during three weeks after the burn. Therefore, a close monitoring and intensive management of renal dysfunction is necessary to prevent burn-induced acute renal failure as well as to lower mortality in patients with major burns.

Effect of thyroid hormone on the alcohol dehydrogenase activities in rat tissues.

The effects of thyroid hormone on hepatic and gastric alcohol dehydrogenase (ADH) activities (nM of NADH/min/mg of cytosolic protein) have been investigated in male Sprague Dawley rats treated with thyroxine (1 mg/kg, po) for 14 days. Whereas hepatic ADH activity in thyroxine-treated rats decreased by 61.3% of control rats (26.4 vs 43.2, p<0.001), gastric ADH activity increased by 262.9% of control rats (4.9 vs 1.9, p<0.001). As for the activities of the lung and kidney, thyroxine treatment did not produce any statistically significant changes. These data suggest that thyrotoxicosis causes a decrease of hepatic alcohol metabolism, and that the increase of gastric ADH activity in thyrotoxic rats can partly restore the first-pass metabolism of ethanol.

Uptake and incorporation of docosahexaenoic acid (DHA) into neuronal cell body and neurite/nerve growth cone lipids: evidence of compartmental DHA metabolism in nerve growth factor-differentiated PC12 cells.

Docosahexaenoic acid (DHA) accumulates in nerve endings of the brain during development. It is released from the membrane during ischemia and electroconvulsive shock. DHA optimizes neurologic development, it is neuroprotective, and rat adrenopheochromocytoma (PC12) cells have decreased PLA2 activity when DHA is present. To characterize DHA metabolism in PC12 cells, media were supplemented with [3H]DHA or [3H]glycerol. Fractions of nerve growth cone particles (NGC) and cell bodies were prepared and the metabolism of the radiolabeled substrates was determined by thin-layer chromatography. [3H]glycerol incorporation into phospholipids indicated de novo lipid synthesis. [3H]DHA uptake was more rapid in the cell bodies than in the NGC. [3H]DHA first esterified in neutral lipids and later in phospholipids (phosphatidylethanolamine). [3H]glycerol primarily labeled phosphatidylcholine. DHA uptake was compartmentalized between the cell body and the NGC. With metabolism similar to that seen in vivo, PC12 cells are an appropriate model to study DHA in neurons.

Inhibition of azoxymethane-induced colon cancer by orange juice.

Previous research has shown that hesperidin, a flavanone glycoside in orange juice, inhibits colon carcinogenesis and that feeding double-strength orange juice delays the onset of chemically induced mammary cancer in rats. This study determined whether feeding single-strength, pasteurized orange juice would inhibit azoxymethane (AOM)-induced colon cancer in male Fischer 344 rats. Colon cancer was initiated by injecting AOM (15 mg/kg body wt) at 22 and 29 days of age. One week after the second AOM injection, orange juice replaced drinking water for the experimental group (n = 30). The rats were killed 28 weeks later, and tumors were removed for histological analysis. Feeding orange juice reduced tumor incidence by 22% (p < 0.05). Tumor reduction was associated with a decreased labeling index and proliferation zone in the colonic mucosa. Hesperidin, other flavonoids, limonin 17-beta-D-glucopyranoside, and other limonoid glucosides are potential chemopreventive agents in orange juice that could account for the decreased colon tumorigenesis associated with feeding orange juice.

Cytosolic estrogen receptor concentrations in the lumbosacral spinal cord fluctuate during the estrous cycle.

Estrogen responsive neurons have been anatomically identified with autoradiographic and immunohistochemical techniques and their distribution mapped in the lumbosacral spinal cord of female rats. Such neurons contain estrogen receptors (ERs). The present study was undertaken to: 1) quantify cytosolic estrogen receptor (ER) concentrations in the lumbosacral spinal cord and 2) determine if there is a relationship between cytosolic ER concentrations and fluctuations in serum estradiol (SE2) levels during the estrous cycle. Lumbosacral spinal segments were removed from intact cycling rats during the morning of proestrus, the afternoon of proestrus, and the morning of estrus, metestrus and diestrus. Trunk blood was collected at euthanasia and SE2 levels were determined using radioimmunoassay. Cytosolic ER concentrations were measured using a dextran-charcoal coated tube method. Concentrations of cytosolic ERs were low during estrus and metestrus, increased during diestrus with maximum concentrations during the afternoon of proestrus. These changes in ER concentrations paralleled SE2 levels measured in intact cycling animals; i.e., during estrus SE2 levels were low, but began to rise during metestrus, diestrus, and during the morning of proestrus with a maximum peak increase during the afternoon of proestrus. These data indicate there are fluctuations of cytosolic ER concentrations during the estrous cycle and that these changes coincide with changing SE2 concentrations suggesting that ER content is influenced by SE2.

Dietary zinc deficiency alters 5 alpha-reduction and aromatization of testosterone and androgen and estrogen receptors in rat liver.

We studied the effects of zinc deficiency on hepatic androgen metabolism and aromatization, androgen and estrogen receptor binding, and circulating levels of reproductive hormones in freely fed, pair-fed and zinc deficient rats. Hepatic conversion of testosterone to dihydrotestosterone was significantly less, but formation of estradiol from testosterone was significantly greater in rats fed the zinc-deficient diet compared with freely fed and pair-fed control rats. There were significantly lower serum concentrations of luteinizing hormone, estradiol and testosterone in rats fed the zinc-deficient diet. No difference in the concentration of serum follicle-stimulating hormone was observed between the zinc-deficient group and either control group. Scatchard analyses of the receptor binding data showed a significantly higher level of estrogen receptor in zinc-deficient rats (36.6 +/- 3.4 fmol/mg protein) than in pair-fed controls (23.3 +/- 2.2 fmol/mg protein) and a significantly lower level of androgen binding sites in rats fed the zinc-deficient diet (6.7 +/- 0.7 fmol/mg protein) than in pair-fed control rats (11.3 +/- 1.2 fmol/mg protein). There were no differences in hepatic androgen and estrogen receptor levels between freely fed and pair-fed controls. These findings indicate that zinc deficiency reduces circulating luteinizing hormone and testosterone concentrations, alters hepatic steroid metabolism, and modifies sex steroid hormone receptor levels, thereby contributing to the pathogenesis of male reproductive dysfunction.

Bone histomorphometry of ovariectomized or orchiectomized rats fed a moderately magnesium-deficient fructose diet and treated with exogenous oestrogen or testosterone.

To investigate the effects of sex hormones on bone histomorphometry, and bone density (BMD), 10 week old ovariectomized (OVX), orchiectomized (ORX), and sham-operated (SHAM) rats fed a moderately magnesium-deficient fructose diet were studied. One third of the OVX and ORX rats were injected with beta-oestradiol-3-benzoate; another third, testosterone cypionate; and the remaining SHAM rats, vehicle only. After 14 weeks, a 24 h urine sample was collected for measurements of calcium, phosphorus and cyclic AMP (cAMP). Blood was collected for determination of calcium, phosphorus, and parathyroid hormone (PTH). Femurs and tibias were removed and weighed. Femurs were used to measure bone areas, mineral contents (BMC), and BMD. Tibias were used for bone histomorphometry (that is, trabecular numbers, thicknesses, % areas and separations). Oestrogen treatment increased serum and urine calcium significantly in both OVX and ORX rats, whereas testosterone decreased serum and urine calcium significantly. Oestrogen decreased urinary cAMP and PTH in both OVX and ORX rats, whereas testosterone treatment increased them significantly. Oestrogen treatment increased BMD, trabecular numbers, thicknesses, and % areas, and decreased bone separations in both OVX and ORX rats. In contrast, testosterone did not increase these bone indices in either OVX or ORX rats; rather, it increased bone separations by decreasing bone strength. Testosterone treatment improved trabecular histomorphometry slightly in OVX rats. The results of the present study are concordant with our previous findings that exogenous oestrogen treatment can prevent osteoporosis in either OVX or ORX rats, whereas exogenous testosterone cannot.

Exogenous oestrogen affects calcium metabolism differently from exogenous testosterone in ovariectomized or orchiectomized rats fed a high fructose diet severely deficient in magnesium.

To investigate interactions between sex hormones, dietary fructose, and a severe magnesium deficiency on calcium metabolism, 10 week old ovariectomized (OVX) female, and orchiectomized (ORX) males rats were studied. The OVX and ORX animals were divided into two groups: one half of the animals in each group was injected with beta-oestradiol-3-benzoate dissolved in sesame oil twice a week; the other half was injected with testosterone cypionate in sesame oil twice a week. All animals were pari-fed a severely magnesium-deficient fructose diet. After a 4 week experimental period, a 24 h urine sample was collected for measurements of cAMP, calcium, magnesium, and phosphorus. Blood was collected for determination of calcium, magnesium, phosphorus, 25-hydroxy- and 1.25-dihydroxycholecalciferol [25(OH)D, 1.25(OH)2D], and parathyroid hormone (PTH). Femurs were used for measurements of bone mineral content (BMC) and density (BMD). Oestrogen treatment produced hypercalcaemia and hypercalciuria, and, further, this was higher in female than in male rats. In contrast, testosterone treatment produced hypocalcaemia and hypocalciuria. Hypocalcaemia in testosterone-treated animals may stimulate secretion of PTH. Testosterone-treated animals had significantly lower BMD than oestrogen-treated animals. High circulating PTH seemed to cause bone loss in the testosterone group. High PTH may stimulate hydroxylation of 25(OH) D to 1.25(OH)2D in the kidneys, and high circulating 1.25(OH)2D would antagonize bone formation. Either endogenous or exogenous oestrogen increased kidney calcification. The study indicates that oestrogen-fructose-magnesium interaction on calcium metabolism was significantly different from that of testosterone.