Fast ultrasound-assisted treatment of urine samples for chronopotentiometric stripping determination of mercury at gold film electrodes

This work describes an efficient, fast, and reliable analytical methodology for mercury determination in urine samples using stripping chronopotentiometry at gold film electrodes. The samples were sonicated in the presence of concentrated HCl and H2O2 for 15 min in order to disrupt the organic ligands and release the mercury. Thirty samples can be treated over the optimized region of the ultrasonic bath. This sample preparation was enough to allow the accurate stripping chronopotentiometric determination of mercury in the treated samples. No background currents and no passivation of the gold film electrode due to the sample matrix were verified. The samples were also analyzed by cold vapour atomic absorption spectrometry (CV-AAS) and good agreement between the results was verified. The analysis of NIST SRM 2670 (Toxic Metals in Freeze-Dried Urine) also validated the proposed electroanalytical method. Finally, this method was applied for mercury evaluation in urine of workers exposed to hospital waste incinerators. (c) 2006 Elsevier B.V. All rights reserved.

EFFECT OF LATERAL HYPOTHALAMUS LESIONS ON THE WATER AND SALT INTAKE, AND SODIUM AND URINE EXCRETION INDUCED BY ACTIVATION OF THE MEDIAN PREOPTIC NUCLEUS IN CONSCIOUS RATS

In this-study we investigated the influence of electrolytic lesion of the lateral hypothalamus (LH) on the water and salt appetite, and the natriuretic, diuretic and cardiovascular effects induced by angiotensinergic, cholinergic and noradrenergic stimulation of the median preoptic nucleus (MnPO) in rats. Male Holtzman rats were implanted with a cannula into the MnPO. Other groups of sham- and LH-lesioned rats received a stainless steel cannula implanted into the MnPO. ANGII injection into the MnPO induced water and sodium intake, and natriuretic, diuretic, presser and tachycardic responses. Carbachol induced water intake, and natriuretic, presser and bradycardic responses, whereas noradrenaline increased urine, sodium excretion and blood pressure, and induced bradycardia. In rats submitted to LH-lesion only, water and sodium intake was reduced compared with sham rats. LH lesion also reduced the sodium ingestion induced by ANGII (12 ng) into the MnPO. In LH-lesioned rats, the dipsogenic, diuretic and presser responses induced by ANGII (12 ng), carbachol (2 nmol) and noradrenaline (20 nmol) injection into the MnPO were reduced. The same occurred with sodium excretion when carbachol (2 nmol) and noradrenaline (20 nmol) were injected into the MnPO of LH-lesioned rats, whereas ANGII(12 ng) induced an increase in sodium excretion. These data show that electrolytic lesion of the LH reduces fluid and sodium intake, and presser responses to angiotensinergic, cholinergic and noradrenergic activation of the MnPO. LH involvement with MnPO excitatory and inhibitory mechanisms related to water and sodium intake, sodium excretion and cardiovascular control is suggested.

First-void versus midstream urine culture for detection of Ureaplasma urealyticum in the urinary tract

Quantitative Ureaplasma urealyticum culture was performed on clean first-void and midstream urine to evaluate the presence of these mollicutes in the urinary tract. The results, expressed as color changing units (CCU), showed that 14 (63%) of the 22 Ureaplasma urealyticum positive patients yielded counts equal to or higher that 10(7) CCU/mL for both the initial and the middle urine specimens. No abnormal chemical or microscopic findings (protein content, leukocyte numbers) were observed. The occurrence of U. urealyticum in midstream urine samples, even when numbers are considered, may be no more than a guide to the presence of ureaplasmas in the urinary tract.

Differential pulse polarographic determination of ceftazidime in urine samples with and without prior extraction

Ceftazidime shows two main polarographic reduction peaks at pH 4.0, that at -0.45 V owing to reduction of the C=N bond in the methylethoxyimino group and that at -1.00 V owing to the reductive elimination of pyridine: the first peak is particularly suitable for the determination of ceftazidime. Ceftazidime can also be determined indirectly using the tensammetric peak at -0.60 V (in Britton-Robinson buffer pH 9.5) of pyridine liberated on hydrolysis. Ceftazidime can be determined in urine using the direct method only after Cls solid phase extraction, but it can be determined directly in the urine by hydrolysing it and using the pyridine peak. (C) 1997 Elsevier B.V. B.V.

Biomass production and secretion of hydrolytic enzymes are influenced by the structural complexity of the nitrogen source in Fusarium oxysporum and Aspergillus nidulans

The structural complexity of the nitrogen sources strongly affects biomass production and secretion of hydrolytic enzymes in filamentous fungi. Fusarium oxysporum and Aspergillus nidulans were grown in media containing glucose or starch, and supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids), peptides (peptone) and protein (gelatin). In glucose, when the initial pH was adjusted to 5.0, for both microorganisms, higher biomass production occurred upon supplementation with a nitrogen source in the peptide form (peptone and gelatin). With a close to neutrality pH, biomass accumulation was lower only in the presence of the ammonium salt. When grown in starch, biomass accumulation and secretion of hydrolytic enzymes (amylolytic and proteolytic) by Fusarium also depended on the nature of the nitrogen supplement and the pH. When the initial pH was adjusted to 5.0, higher growth and higher amylolytic activities were detected in the media supplemented with peptone, gelatin and casamino acids. However, at pH 7.0, higher biomass accumulation and higher amylolytic activities were observed upon supplementation with peptone or gelatin. Ammonium sulfate and casamino acids induced a lower production of biomass, and a different level of amylolytic enzyme secretion: high in ammonium sulfate and low in casamino acids. Secretion of proteolytic activity was always higher in the media supplemented with peptone and gelatin. Aspergillus, when grown in starch, was not as dependent as Fusarium on the nature of nitrogen source or the pH. The results described in this work indicate that the metabolism of fungi is regulated not only by pH, but also by the level of structural complexity of the nitrogen source in correlation to the carbon source.

REDUCTION OF URINE VOLUME AMELIORATES ADRIAMYCIN-INDUCED NEPHROPATHY

1. Adriamycin, a commonly used antineoplastic antibiotic, induces glomerular lesions in rats, resulting in persistent proteinuria and glomerulosclerosis.2. The effect of urine volume on the progression of adriamycin-induced nephropathy was studied in 70 male Wistar rats (180-200 g) observed for 30 weeks and separated into 4 groups: healthy control group (HCG, N = 10) inoculated iv with 1 ml of saline, and nephrotic groups inoculated iv with a single dose of adriamycin of 3 mg/kg body weight. The nephrotic rats were separated into 3 groups (N = 20): nephrotic control group (NCG) receiving only adriamycin; dehydrated nephrotic group (DNG) water deprived for 36 h within each 48-h period, and furosemide nephrotic group (FNG) treated with 12 mg/dl furosemide, and 0.9 g/dl NaCl in the drinking water.3. The 30-week survival rates of the DNG (100%) and HCG (100%) were significantly higher than those of the NCG (85%) and FNG (55%).4. The proteinuria observed in the HCG (range, 7.38 +/- 0.7 to 13.6 +/- 1.27 mg/24 h) was significantly lower than that observed for all the nephrotic groups throughout the experiment. The DNG presented significantly less proteinuria (range, 42.71 +/- 6.83 to 140.10 +/- 19.22 mg/24 h) than the NCG (range, 35.32 +/- 7.64 to 250.00 +/- 25.91 mg/24 h) from week 10 on. There was no significant difference between the mean 24-h proteinuria of the NCG (range, 35.32 +/- 7.64 to 250.00 +/- 25.91 mg/24 h) and the FNG (range, 35.82 +/- 7.91 to 221.54 +/- 26.74).5. The mean frequency of damaged glomeruli was 0.3% +/- 0.3 for HCG, 42% +/- 6% for CNG, 40.8% +/- 8% for DNG, and 47% +/- 14% for FNG. The median value of the tubulointerstitial lesion, evaluated by a semiquantitative method, was 0 in HCG, 10 in CNG, 8.5 in DNG and 9.5 in FNG(P<0.05 for all groups compared to HCG).6. The data indicate that reduction of urine volume has a protective effect on adriamycin-induced nephropathy.

Determination of cinnamic acid in human urine by differential-pulse polarography

The differential pulse polarographic behaviour of cinnamic acid was studied in acetate and phosphate buffer solutions (pH 3.5-7.5). The reduction mechanism is discussed. The drug can be determined at pH 5.0 over the concentration range 5 X 10(-5)-1 X 10(-3) mol l(-1). The effect of tetraalkylammonium salts on the electroanalytical determination of cinnamic acid was investigated, the direct determination of the drug (0.7-5.5 mu g ml(-1)) in urine samples diluted with acetate buffer (pH 5.0) can be effected in the presence of 1 x 10(-3) mol l(-1) cetyldimethylethylammonium bromide solution. The detection limit was found to be 0.1 mu g ml(-1). The relative standard deviation from six determinations at the 5.5 mu g ml(-1) level was 1%.

Medial Septal Area Vasopressin Receptor Subtypes in the Regulation of Urine and Sodium Excretion in Rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Functional and structural analysis of two fibrinogen-activating enzymes isolated from the venoms of Crotalus durissus terrificus and Crotalus durissus collilineatus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)