Determination of Creatine and Creatinine in Urine

Thin-Layer Potentiometry for Creatinine Detection in Undiluted Human Urine Using Ion-Exchange Membranes as Barriers for Charged Interferences

Herein, thin-layer potentiometry combined with ion-exchange membranes as barriers for charged interferences is demonstrated for the analytical detection of creatinine (CRE) in undiluted human urine. Briefly, CRE diffuses through an anion-exchange membrane (AEM) from a sample contained in one fluidic compartment to a second reservoir, containing the enzyme CRE deiminase. There, CRE reacts with the enzyme, and the formation of ammonium is dynamically monitored by potentiometric ammonium-selective electrodes. This analytical concept is integrated into a lab-on-a-chip microfluidic cell that allows for a high sample throughput and the operation under stop-flow mode, which allows CRE to passively diffuse across the AEM. Conveniently, positively charged species (i.e., potassium, sodium, and ammonium, among others) are repelled by the AEM and never reach the ammonium-selective electrodes; thus, possible interference in the response can be avoided. As a result, the dynamic potential response of the electrodes is entirely ascribed to the stoichiometric formation of ammonium. The new CRE biosensor exhibits a Nernstian slope, within a linear range of response from 1 to 50 mM CRE concentration. As expected, the response time (15-60 min) primarily depends on the CRE diffusion across the AEM. CRE analysis in urine samples displayed excellent results, without requiring sample pretreatment (before the introduction of the sample in the microfluidic chip) and with high compatibility with development into a potential point-of-care clinical tool. In an attempt to decrease the analysis time, the presented analytical methodology for CRE detection is translated into an all-solid-state platform, in which the enzyme is immobilized on the surface of the ammonium-selective electrode and with the AEM on top. While more work is necessary in this direction, the CRE sensor appears to be promising for CRE analysis in both urine and blood.

Oleuropein aglycone enhances UCP1 expression in brown adipose tissue in high-fat-diet-induced obese rats by activating β-adrenergic signaling

Oleuropein is the pungent principle of raw olives. Oleuropein aglycone (OA) is a major phenolic compound in extra virgin olive oil and the absorbed form of oleuropein. We aimed to determine the mechanism underlying the nutritional effects of oleuropein and OA on interscapular brown adipose tissue (IBAT) in rats with high-fat (HF) diet-induced obesity by examining the agonistic activity of oleuropein and OA toward the transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1). Four-week-old male Sprague-Dawley rats were fed an HF (palm oil 30% wt:wt) diet alone or with oleuropein (HF-O, 1 g/kg diet) for 28 days. In rats fed HF-O compared to HF, urinary noradrenaline, adrenaline and UCP1 levels in IBAT were significantly higher, whereas plasma leptin levels and the total weight of the abdominal cavity adipose tissue were significantly lower. In anaesthetized 7-week-old male Sprague-Dawley rats, the OA (3.8 mg of intravenous injection)-induced increase in plasma noradrenaline secretion was suppressed by TRPA1 or TRPV1 antagonist and by a β2- or β3-adrenoceptor antagonist. Furthermore, OA-activated rat and human TRPV1s expressed on HEK293 cells at the same level as zingerone (pungent component in ginger). OA also activated humanTRPA1, and its potency was approximately 10-fold stronger than that for TRPV1. These findings suggest that OA is the agonist of both TRPA1 and TRPV1 and that OA enhances UCP1 expression in IBAT with a concomitant decrease in the visceral fat mass of HF-diet-induced obese rats through enhanced noradrenaline secretion via β-adrenergic action following TRPA1 and TRPV1 activation.

Creatine supplementation and oxidative stress in rat liver

BACKGROUND

The objective of this study was to determine the effects of creatine supplementation on liver biomarkers of oxidative stress in exercise-trained rats.

METHODS

Forty 90-day-old adult male Wistar rats were assigned to four groups for the eight-week experiment. Control group (C) rats received a balanced control diet; creatine control group (CCr) rats received a balanced diet supplemented with 2% creatine; trained group (T) rats received a balanced diet and intense exercise training equivalent to the maximal lactate steady state phase; and supplemented-trained (TCr) rats were given a balanced diet supplemented with 2% creatine and subjected to intense exercise training equivalent to the maximal lactate steady state phase. At the end of the experimental period, concentrations of creatine, hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances (TBARS) were measured as well as the enzyme activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-GPx) and catalase (CAT). Liver tissue levels of reduced glutathione (GSH), oxidized glutathione (GSSG) and the GSH/GSSG ratio were also determined.

RESULTS

Hepatic creatine levels were highest in the CCr and TCr groups with increased concentration of H2O2 observed in the T and TCr animal groups. SOD activity was decreased in the TCr group. GSH-GPx activity was increased in the T and TCr groups while CAT was elevated in the CCr and TCr groups. GSH, GGS and the GSH/GSSG ratio did not differ between all animal subsets.

CONCLUSIONS

Our results demonstrate that creatine supplementation acts in an additive manner to physical training to raise antioxidant enzymes in rat liver. However, because markers of liver oxidative stress were unchanged, this finding may also indicate that training-induced oxidative stress cannot be ameliorated by creatine supplementation.

Oleuropein supplementation increases urinary noradrenaline and testicular testosterone levels and decreases plasma corticosterone level in rats fed high-protein diet

The effects of oleuropein, a phenolic compound in extra virgin olive oil, on protein metabolism were investigated by measuring testicular testosterone and plasma corticosterone levels in rats fed diets with different protein levels. In Experiment 1, rats were fed experimental diets with different protein levels (40, 25 and 10 g/100 g casein) with or without 0.1 g/100 g oleuropein. After 28 days of feeding, the testosterone level in the testis was significantly higher and the plasma corticosterone level was significantly lower in rats fed the 40% casein diet with oleuropein than in those fed the same diet without oleuropein. The urinary noradrenaline level, nitrogen balance and hepatic arginase activity were significantly higher in rats fed the 40% casein diet with oleuropein supplementation than in those fed the 40% casein diet without oleuropein supplementation. In Experiment 2, the effects of oleuropein aglycone (a major phenolic compound in extra virgin olive oil and the absorbed form of oleuropein ingested in the gastrointestinal tracts) on the secretion of luteinizing hormone (LH) from the pituitary gland, which regulates testosterone production in the testis, were investigated in anesthetized rats. Plasma LH level increased dose dependently after the administration of oleuropein aglycone (P<.001, r=0.691). These findings suggest that dietary supplementation with 0.1 g/100 g oleuropein alters the levels of hormones associated with protein anabolism by increasing urinary noradrenaline and testicular testosterone levels and decreasing plasma corticosterone level in rats fed a high-protein diet.

FXa Inhibition and Coagulation Changes During DVT Prophylaxis by Enoxaparin Over the Course of a 15-Day Follow-Up in Septic Patients

The objective of our study was to examine the changes in coagulation parameters and inflammatory reaction over the course of 15 days in patients with severe sepsis. We tried to identify mechanisms by which sepsis-induced pathophysiological changes may influence the effectiveness of subcutaneously (SC) administered enoxaparin 40 mg once daily.

A total of 16 patients (8 men, 8 women; age 35-83 years) meeting the inclusion criteria of severe sepsis were enrolled in this study. The follow-up was performed on days 1, 2, 3, 6, 9, 12, and 15 of hospitalization at the intensive care unit (ICU). Blood coagulation (activated partial thromboplastin time [aPTT], prothrombin time [PT], fibrinogen, antithrombin (AT), protein C [PC], D-dimer, fragment 1.2 [F1.2], factor Xa [FXa] inhibition) and inflammatory reactants (interleukin 6 [IL-6], C-reactive protein [CRP], orosomucoid, α-1-antitrypsin) were tested.

The mean FXa inhibition was 0.17 (±0.17) IU/mL. The arbitrarily established range of FXa inhibition for prophylaxis, 0.2 to 0.4 IU/mL, was reached in 22 cases (20%), while in 74 cases (68%), it was below and in 13 cases (12%) above the aforementioned range. Factor Xa inhibition positively correlated with AT (r = .42; P < .001) and PC (r = .45; P < .001) activities. A negative correlation was found between the FXa inhibition and α-1-antitrypsin concentrations (r = —.33; P = .01) but only in the subgroup with α-1-antitrypsin concentrations ≥2.2 g/L.

We confirmed that in most patients with sepsis, the prophylaxis with enoxaparin did not lead to the required FXa inhibition. The inhibition of FXa by enoxaparin depends mainly on the AT and PC activities.

Increased urinary protein excretion after intravenous injection of furosemide in man

The furosemide-induced increase in protein excretion, and its relations to 1) the size of protein molecules as reflected by three enzymes, and 2) glomerular filtration rate (GFR), plasma renin activity (PRA) and prostaglandin (PG) E2 and F2 alpha excretions were studied in 14 outpatients with normal renal function and 13 healthy males. Furosemide (120 mg) was given intravenously, and thereafter the protein excretion and the above parameters were monitored for 1--2 hours. In both groups, furosemide caused a transient increase in protein excretion. The excretion of the largest molecule, beta-glucuronidase, rose to 6.3-fold, while those of N-acetyl-beta-D-glucosaminidase and of the smallest molecule, alpha-amylase, increased by 91 and 37%, respectively. GFR increased, too, but markedly less than the protein excretion. PGE2 and PGF2 alpha excretions increased more than GFR and changed simultaneously with the excretion of proteins. Furosemide also caused a marked increase in PRA. This lasted, however, much longer than the rise in PG and protein excretion or GFR. The results suggest that the furosemide-induced increase in protein excretion is 1) related to the molecular size of proteins, 2) partly due to the rise in GFR, 3) simultaneous with the change in PG excretion. Our findings also agree with the view that furosemide causes changes in glomerular permeability.

Extra virgin olive oil increases uncoupling protein 1 content in brown adipose tissue and enhances noradrenaline and adrenaline secretions in rats

The effects of extra virgin olive oil (EV-olive oil) on triglyceride metabolism were investigated by measuring the degree of thermogenesis in interscapular brown adipose tissue (IBAT) and the rates of noradrenaline and adrenaline secretions in rats, both in vivo and in situ. In Experiment 1 (in vivo), rats were given an isoenergetic high-fat diet (30% fat diet) containing corn oil, refined olive oil, or EV-olive oil. After 28 days of feeding, the final body weight, weight gain, energy efficiency, perirenal adipose tissue and epididymal fat pad and plasma triglyceride concentrations were the lowest in the rats fed the EV-olive oil diet. The content of uncoupling protein 1 (UCP1) in IBAT and the rates of urinary noradrenaline and adrenaline excretions were the highest in the rats fed the EV-olive oil diet. In Experiment 2 (in situ), the effects of the extract of the phenolic fraction from EV-olive oil and a compound having excellent characteristics as components of EV-olive oil, hydroxytyrosol, on noradrenaline and adrenaline secretions were evaluated. The intravenous administration of the extract of the phenolic fraction from EV-olive oil significantly increased plasma noradrenaline and adrenaline concentrations, whereas that of hydroxytyrosol had no effect. These results suggest that phenols except hydroxytyrosol in EV-olive oil enhance thermogenesis by increasing the UCP1 content in IBAT and enhancing noradrenaline and adrenaline secretions in rats.

Long-Term Correction of Ornithine Transcarbamylase Deficiency by WPRE-Mediated Overexpression Using a Helper-Dependent Adenovirus

The urea cycle disorders (UCDs) are important models for developing gene replacement therapy for liver diseases. Long-term correction of the most common UCD, ornithine transcarbamylase (OTC) deficiency, has yet to be achieved in clinical or preclinical settings. The single human clinical trial using early-generation adenovirus (Ad) failed to show any biochemical correction. In adult OTC-deficient mice, an E1/E2-deleted Ad vector expressing the mouse OTC gene, but not the human, was only transiently therapeutic. By using post-transcriptional overexpression in the context of the less immunogenic helper-dependent adenoviral vector, we achieved metabolic correction of adult OTC-deficient mice for >6 months. Demonstrating this result were normalized orotic aciduria, normal hepatic enzyme activity, and elevated OTC RNA and protein levels in the absence of chronic hepatotoxicity. Overexpressing the human protein may have overcome two potential mechanisms accounting for poor cross-species complementation: a kinetic block at the level of mitochondrial import or a dominant negative effect by the mutant polypeptide. These data represent an important approach for treating human inborn errors of hepatocyte metabolism like the UCDs that require high-level transduction and gene expression for clinical correction.

Midarm computerized tomography fat, muscle and total areas correlation with nutritional assessment data

BACKGROUND AND OBJECTIVES

Correlated nutritional assessment data (anthropometric, bioimpedance and biochemical) with computerized tomography (CT) of total, muscle and fat midarm areas. Total body fat and fat-free mass were estimated using bioimpedance. Daily urinary urea and creatinine were also quantified. In all, 28 subjects (13 males, 15 females) were evaluated and, they were clinically divided in obese, malnourished and control subjects.

DESIGN

Quantification of total, fat muscle midarm areas by tomography and anthropometry and total body fat and free-fat mass by bioimpedance.

RESULTS

CT values were 29% higher for fat area and 4-5% lower for total and muscle midarm areas compared against anthropometric data. The midarm skinfold thickness highly correlated with CT fat midarm area. Total body fat and free-fat mass bioimpedance data showed significant correlation with CT midarm data. Urinary creatinine correlated with CT muscle midarm area.

CONCLUSION

Utilization of anthropometry can lead to error estimation of fat and fat-free arm areas and that bioimpedance gives fair correlation between total body and CT midarm measurements.

Air concentrations and urinary metabolites of polycyclic aromatic hydrocarbons among paving and remixing workers

The exposure of paving workers to polycyclic aromatic hydrocarbons (PAH) during stone mastic asphalt (SMA) paving and remixing was evaluated. The effects on the workers' PAH exposure were also evaluated during the use of an industrial by-product, coal fly ash (CFA), instead of limestone as the filler in the SMA. The PAH exposure was measured by personal air sampling and by analysing the levels of urinary naphthols, phenanthrols and 1-hydroxypyrene (1-OHP) in the workers' pre- and post-shift urine samples. The respiratory PAH exposure of the paving workers (geometric mean (GM) 5.7 microg m(-3)) was about ten-fold that of the traffic controllers (GM 0.43 microg m(-3)). The levels of PAH metabolites were significantly higher (p < 0.05) in the post-shift urine samples than in the pre-shift urine samples, and the levels of metabolites in the post-shift urine of paving workers were significantly higher than in that of the controls (p < 0.01). Urinary 1-naphthol correlated well with the airborne concentrations of the two- to three-ring PAHs (r = 0.544, p = 0.003) and naphthalene (r = 0.655, p < 0.001), when non-smoking paving workers were tested. A good correlation was observed between urinary 1-OHP and the airborne concentrations of the four- to six-ring PAHs (r = 0.524, p = 0.003) as well as total PAHs (r = 0.575, p = 0.001). The concentrations of 1-OHP and phenanthrols in the urine of the pavers were significantly higher (p < 0.01) during remixing than during SMA paving. The CFA in the asphalt had no effect on the airborne PAH exposure or on the concentrations of the PAH metabolites in the paving workers' urine.

Biological monitoring of aromatic diisocyanates in workers exposed to thermal degradation products of polyurethanes

Exposure to diisocyanates was assessed by biological monitoring among workers exposed to the thermal degradation products of polyurethanes (PURs) in five PUR-processing environments. The processes included grinding and welding in car repair shops, milling and turning of PUR-coated metal cylinders, injection moulding of thermoplastic PUR, welding and cutting of PUR-insulated district heating pipes during installation and joint welding, and heat-flexing of PUR floor covering. Isocyanate-derived amines in acid-hydrolysed urine samples were analysed as perfluoroacylated derivatives by gas chromatography mass spectrometry in negative chemical ionisation mode. The limits of quantification (LOQs) for the aromatic diamines 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA) and 4,4'-methylenedianiline (4,4'-MDA) were 0.25 nmol l(-1), 0.25 nmol l(-1) and 0.15 nmol l(-1), respectively. The LOQ for the aliphatic diamines hexamethylenediamine (HDA), isophoronediamine (IpDA) and 4,4'-diaminodicyclohexyl methane (4,4'-DDHM) was 5 nmol l(-1). TDA and MDA were detected in urine samples from workers in car repair shops and MDA in samples from workers welding district heating pipes. The 2,4-TDA isomer accounted for about 80% of the total TDA detected. No 2.6-TDA was found in the urine of non-exposed workers. The highest measured urinary TDA and MDA concentrations were 0.79 nmol mmol(-1) creatinine and 3.1 nmol mmol(-1) creatinine, respectively. The concentrations found among non-exposed workers were 0.08 nmol mmol(-1) creatinine for TDA and 0.05 nmol mmol(-1) creatinine for MDA (arithmetic means). Exposure to diisocyanates originating from the thermal degradation of PURs are often intermittent and of short duration. Nevertheless, exposure to aromatic diisocyanates can be identified by monitoring diisocyanate-derived amines in acid-hydrolysed urine samples.

Biological versus ambient exposure monitoring of creosote facility workers

Traditional methods for monitoring occupational creosote exposure have focused on inhalation. However, there is evidence that dermal exposure contributes importantly to total systemic dose, as measured by biological monitoring methods. This study was conducted to further characterize the relationships between inhalation and dermal exposures to creosote, and to compare traditional ambient exposure monitoring versus biological monitoring in 36 creosote-exposed wood treatment workers. Full-shift personal air samples were obtained, along with post-shift and next-day urine measurements for 1-hydroxypyrene. There was little or no correlation between airborne measures and urinary 1-hydroxypyrene (r2 = 0.05 to 0.35). More than 90% of 1-hydroxypyrene could be attributed to dermal exposure. These data indicate that traditional monitoring methods may be inappropriate for creosote workers, raising concerns about the adequacy of methods currently mandated by the Occupational Safety and Health Administration.

Monoterpene and wood dust exposures: work-related symptoms among Finnish sawmill workers

BACKGROUND

Monoterpenes and wood dust are released into the work environment during sawing of fresh wood. Symptoms related to exposure to monoterpenes and wood dust include irritation of the eyes, mucous membrane, and skin.

METHODS

We studied 22 sawhouse workers who process pine and spruce in 1997-99. Exposure to monoterpenes was assessed by determining monoterpenes in air and verbenols in urine by gas chromatography using flame ionization detection. Wood dust was determined gravimetrically. A questionnaire was used to evaluate work-related subjective symptoms.

RESULTS

Exposures to monoterpenes (geometric mean, GM) among sawhouse workers were 61-138 mg/m(3) and 2.0-13 mg/m(3) during processing of pine and spruce, respectively. Urinary verbenol correlated well with worker exposure to the alpha-pinene fraction of monoterpenes. The inhalable dust concentration in the breathing zone was 0.5- 2.2 mg/m(3) during pine processing and 0.4-1.9 mg/m(3) during spruce processing. The prevalence of symptoms, in the eyes or respiratory tract, was high during both seasons and in connection with either tree species.

CONCLUSIONS

The highest monoterpene concentration (GM), in the breathing zone, measured during processing of pine, was less than one-fourth of the Finnish occupational exposure limit (OEL, 570 mg/m(3)). Verbenol concentrations in postshift urine samples reflected accurately the exposure to monoterpenes. The concentrations of inhalable dust (GM) were less than one-half the Finnish OEL (5 mg/m(3)). No significant differences in dust exposure were observed among tree species processed. Work-related symptoms appeared to correlate with monoterpene exposure during processing of pine and with wood dust exposure during processing of spruce.

Garlic supplementation increases testicular testosterone and decreases plasma corticosterone in rats fed a high protein diet

The effects of garlic supplementation on protein metabolism were investigated by measuring testis testosterone and plasma corticosterone in rats fed diets with different protein levels. In Experiment 1, rats were fed experimental diets with different protein levels (40, 25 or 10 g/100 g casein) with or without 0.8 g/100 g garlic powder. After 28 d of feeding, testosterone contents in the testis were significantly higher and plasma corticosterone concentrations were significantly lower in rats fed 40 and 25% casein diets with garlic powder than in those fed the same diets without garlic powder. Urinary excretion of 17-ketosteroid (an index of testosterone), nitrogen balance and hepatic arginase activity were significantly higher in rats fed the 40% casein diet with garlic powder than in the 40% casein controls. In Experiment 2, the effect of diallyldisulfide (a major volatile sulfur-containing compound in garlic) on the secretion of luteinizing hormone (LH) from the pituitary gland, which regulates testosterone production in the testis, was investigated in anesthetized rats. Plasma LH concentration increased dose dependently after administration of diallyldisulfide (P < 0.01, r = 0.558). These results suggest that dietary supplementation with 0.8 g/100 g garlic alters hormones associated with protein anabolism by increasing testicular testosterone and decreasing plasma corticosterone in rats fed a high protein diet.

[Iron status, malnutrition and acute phase response in HIV-positive patients]

Nutritional status and some iron metabolism parameters of acute phase response (APR) positive and APR-negative AIDS patients were studied. Twenty-nine AIDS patients were submitted to 24h food intake recall, anthropometry, and albumin, C-reactive protein (CRP), hemoglobin, ferritin, and total iron binding capacity (TIBC) measurements. Infection plus serum CRP > 7 mg/dl were criteria for APR presence. Protein-energy malnutrition (PEM) was ascertained by body mass index (BMI) lower than 18.5 kg/m2 and height-creatinine index (HCI < 70%). PEM (77.8 vs 40%) and pulmonary tuberculosis (44. 4 vs 9.5%) were more frequent in APR-positive patients, which also had lower serum albumin (3.7 +/- 0.9 vs 4.3 +/- 0.9 g/dl), TIBC (165. 8 +/- 110.7 vs 265.9 +/- 74.6 mg/dl) and blood hemoglobin (10.5 +/- 1. 8 vs 12.6 +/- 2.3g/dl). Iron intake was similar between groups; however, serum ferritin levels (median, range) were higher among APR-positive (568, 45.3-1814 vs 246, 18.4-1577 ng/ml) patients. HIV-positive adults with systemic response to invading pathogens showed worse nutritional status than those APR-negative. In APR-positive AIDS patients, anemia appears to be unrelated to recent iron intake.

[Malnutrition and hypovitaminosis A in AIDS patients]

Anthropometric measurements and biochemical determinations were performed on HIV-infected individuals and on patients with AIDS from the Ribeirão Preto region, SP, Brazil, in order to evaluate their nutritional and vitamin A status. Plasma retinol was measured by HPLC, and hepatic vitamin A stores were evaluated by the relative dose response (RDR) test. Patients with AIDS presented significant undernutrition, with more marked alterations in the body fat compartment and a relative preservation of the parameters related to muscle mass (pattern of malnutrition predominantly of the marasmus type). Plasma retinol values below 1.05 mumol/L were observed in 25% of the patients with AIDS and in 17.3% of HIV-infected patients and RDR values indicating low body stores of vitamin A were detected in 28% of the subjects. There was no correlation between serum retinol levels and CD4 lymphocyte counts, clinical diagnosis of AIDS, low BMI or AFI. On the other hand, hypovitaminosis A status was associated with low BMI.

Allyl-containing sulfides in garlic increase uncoupling protein content in brown adipose tissue, and noradrenaline and adrenaline secretion in rats

The effects of garlic supplementation on triglyceride metabolism were investigated by measurements of the degree of thermogenesis in interscapular brown adipose tissue (IBAT), and noradrenaline and adrenaline secretion in rats fed two types of dietary fat. In Experiment 1, rats were given isoenergetic high-fat diets containing either shortening or lard with or without garlic powder supplementation (8 g/kg of diet). After 28 d feeding, body weight, plasma triglyceride levels and the weights of perirenal adipose tissue and epididymal fat pad were significantly lower in rats fed diets supplemented with garlic powder than in those fed diets without garlic powder. The content of mitochondrial protein and uncoupling protein (UCP) in IBAT, and urinary noradrenaline and adrenaline excretion were significantly greater in rats fed a lard diet with garlic powder than in those fed the same diet without garlic. Other than adrenaline secretion, differences due to garlic were significant in rats fed shortening, also. In Experiment 2, the effects of various allyl-containing sulfides present in garlic on noradrenaline and adrenaline secretion were evaluated. Administration of diallyldisulfide, diallyltrisulfide and alliin, organosulfur compounds present in garlic, significantly increased plasma noradrenaline and adrenaline concentrations, whereas the administration of disulfides without allyl residues, diallylmonosulfide and S-allyl-L-cysteine did not increase adrenaline secretion. These results suggest that in rats, allyl-containing sulfides in garlic enhance thermogenesis by increasing UCP content in IBAT, and noradrenaline and adrenaline secretion.

Investigation of urinary levels of salbutamol in asthmatic patients receiving inhaled therapy

AIM

Some studies have indicated that over-reliance on inhaled bronchodilator (beta 2-agonist) therapy may worsen asthma control and increase morbidity. The aim of this study was to measure urinary concentrations of salbutamol, the most commonly used bronchodilator, in a relatively large sample of asthmatic patients and examine the potential value of the concentration as an indicator of over-use of salbutamol.

METHOD

The urinary concentrations of the drug were measured in 'spot' urine samples from 102 asthmatic patients (64 community patients and 38 hospital inpatients). A solid-phase extraction technique, using a phenyl-bonded phase and a reversed-phase ion-pair high-performance liquid chromatography assay with UV-detection were developed and used to measure both unchanged salbutamol concentrations and total salbutamol concentrations after enzymatic hydrolysis of the metabolite. In addition, salbutamol concentrations were corrected for urine dilution, with the measured drug expressed per gram of urinary creatinine.

RESULTS

The hospital patients were generally older, had greater disease severity, were more likely to be receiving prophylactic therapy and had received more salbutamol in the past 24 h. The urinary concentrations of salbutamol varied enormously between patients. The median concentrations of unchanged and total drug were 0.38 microgram/ml (range 0-34.4 micrograms/ml) and 2.55 micrograms/ml (range 0-49.8 micrograms/ml), respectively. Even when controlling for dosage in the preceding 24 h, there was a 262-fold and 810-fold variation in the urinary concentrations for unchanged and total salbutamol, respectively, among the community patients. Modest correlations were found between salbutamol concentrations and dosage administered in the preceding 24 h (Spearman's r = 0.67 and 0.54 for unchanged and total drug, respectively; P < 0.001). The correlations improved only slightly with correction for urine dilution (Spearman's r = 0.69 and 0.57 for unchanged and total drug, respectively; P < 0.001).

CONCLUSION

This enormous inter-patient variability, which may be largely due to differences in the pharmacokinetics of salbutamol and inhaler technique, may play a role in the observed worsening of asthma control with the regular use of inhaled bronchodilator drugs and warrants further investigation. Measuring urinary concentrations of salbutamol in spot samples provides only a relatively crude indication of the extent of use of inhaled salbutamol in the preceding 24 h.

Significance of dermal and respiratory uptake in creosote workers: exposure to polycyclic aromatic hydrocarbons and urinary excretion of 1-hydroxypyrene

OBJECTIVES

To evaluate workers' exposure in a creosote impregnation plant by means of ambient and biological monitoring.

METHODS

Naphthalene (vapour phase) and 10 large molecular polycyclic aromatic hydrocarbons (PAHs) (particulate phase) were measured in the breathing zone air during an entire working week. 1-Hydroxypyrene (1-HP) was measured in 24 hour urine as a metabolite of the pyrene found in neat (dermal exposure) and airborne creosote.

RESULTS

Naphthalene (0.4-4.2 mg/m3) showed 1000 times higher concentrations in air than did the particulate PAHs. In total, the geometric mean (range) of three to six ring PAHs was 4.8 (1.2-13.7) micrograms/m3; pyrene 0.86 (0.23-2.1) micrograms/m3, and benzo(a)pyrene 0.012 (0.01-0.05) micrograms/m3. There was no correlation between pyrene and gaseous naphthalene. The correlations between pyrene and the other nine particulate PAHs were strong, and gave a PAH profile that was similar in all air samples: r = 0.83 (three to six ring PAHs); r = 0.81 (three ring PAHs); r = 0.78 (four to six ring PAHs). Dermal exposure was probably very high in all workers, because the daily output of urinary 1-HP exceeded the daily uptake of inhaled pyrene by < or = 50-fold. Urinary 1-HP concentrations were very high, even on Monday mornings, when they were at their lowest (4-22 mumol/mol creatinine). 1-HP seldom showed any net increase over a workshift (except on Monday) due to its high concentrations (16 to 120 mumol/mol creatinine) in the morning samples. 1-HP was always lower at the end of the shift (19 to 85 mumol/mol creatinine) than in the evening (27 to 122), and the mean (SD) change over the working week (47 (18)) was greater than the change over Monday (35 (32)). The timing of 1-HP sampling is therefore very important.

CONCLUSIONS

Urinary 1-HP proved to be a good biomarker of exposure to three to six ring PAHs but not to airborne naphthalene. Hence, biomonitoring based on 1-HP has to be completed with exposure assessment for naphthalene as a marker for creosote volatiles that mainly enter the body through the lungs.

[Serum levels of vitamin A, E, C and B2, carotenoid and zinc in hospitalized elderly patients]

Serum levels of carotenoids, zinc and vitamins A, E, C and B2 were measured in al (n = 202) the elderly patients hospitalized in different wards of the hospital studied from February 1986 to October 1988. The study was conducted on 130 men and 72 women with a mean age of 67.8 years (range: 60 to 88 years). The percentage of nutritional deficiency was 59.5% for zinc, 56.5% for vitamin C, 34.5% for vitamin B2, 25.9% for vitamin E, 13.2% for vitamin A, and 6.8% for carotenoids. Elderly patients with leucoses, megaesophagus, chronic obstructive pulmonary disease, and congestive heart failure represent a group with a high prevalence of deficiency both of zinc and of the vitamins under study. These results show the importance of detecting deficiencies of these micronutrients and provide a basis for a more rational approach to the treatment of elderly patients.

Increased fractional excretion of sulphate in stone formers

This study was performed to determine urinary sulphate excretion in patients with renal stone disease. Stone formers showed a significantly higher fractional excretion of sulphate than control subjects; 80% of stone formers had fractional excretions > 0.26. No significant relationship was established between increased urinary sulphate excretion and any identifiable metabolic disorder, or the recurrence rate of stone episodes. The increase in fractional excretion of sulphate appears to be a more prevalent tubular defect among stone formers than has hitherto been reported.

Contribution of vitamin A deficiency to calculogenic risk factors of urine: studies in children

Studies in experimental animals showed that vitamin A deficiency enhanced the severity of urinary calculi disease. In India, children with low socioeconomic status are the major victims of bladder stone disease, and vitamin A deficiency is also more prevalent among these children. However, no systematic study is available to correlate the vitamin A-deficient status of children with their predisposition to urinary calculi disease. Vitamin A-deficient and normal boys were the subjects of this study. Twenty-four-hour samples of urine were collected from all the children at the beginning of the study and after normalizing the vitamin A status of the deficient children. Important risk factors were estimated in urine. Plasma vitamin A levels were also measured in these children. Among the deficient group, only children with plasma vitamin A levels of 15 micrograms and lower exhibited calcium oxalate crystalluria. Most importantly, abnormal crystalluria was observed in all children whose plasma vitamin A levels were 13 micrograms/dl or less. Compared to normal children the urine of vitamin A-deficient children showed the following changes: (a) reduced concentration of crystal growth inhibitors, namely citrate and glycosaminoglycans; (b) a decline in inhibitory activity toward calcium oxalate crystal growth; and (c) enhanced excretion of high risk factors, namely calcium and oxalate. Correction of vitamin A status normalized the above abnormal properties of urine. The results of this study strongly support the hypothesis that the vitamin A-deficient state is one of the factors that can enhance the risk of urolithiasis in susceptible populations.

Urinary composition in men and women and the risk of urolithiasis

Urinary concentrations of certain biochemical constituents that play an active role in stone formation were determined in 2 h urine collections in healthy men and women (at four phases of the estrous cycle) to elucidate the sex difference in the incidence of urolithiasis. The excretion of the lithogenic substance, calcium, was higher in men than in women during phase I (p less than 0.01) and phase II (p less than 0.05) of the estrous cycle. Oxalate excretion was marginally elevated in men compared to women during each phase. Urinary citrate was lower in men compared to women during each phase (p less than 0.05). Uric acid excretion was lower (p less than 0.05) in men compared with phase I and phase III in women. Estrous phase-related alterations were also observed in the excretion of calcium and citrate in women. The data suggest that low concentrations of calcium and oxalate with an elevated citrate excretion might be responsible for the reduced risk of stone disease in women compared to men.

Influence of sex and age in the risk of urolithiasis--a biochemical evaluation in Indian subjects

Urinary lithogenic promoters and inhibitors were estimated in normal Indian men and women of young and old ages to understand the sex difference in the risk of stone disease. Young men displayed increased phosphate excretion and a higher mean calcium (both lithogenic promoters) and lower excretion of citrate (lithogenic inhibitor) compared to women of the same age indicating that young men are more at risk for calculous disease than women. In the older postmenopausal women, there was increased excretion of calcium and magnesium and a lower mean citrate than in the younger women suggesting that oestrogenic activity during reproductive years appears to offer protection against calculogenesis. This study indicates that sex differences exist in the excretion of lithogenic promoters and inhibitors which partly explain the difference in the incidence of urolithiasis between men and women.

Diazo-positive metabolites in urine from workers exposed to aromatic nitro-amino compounds

The amount of diazo-positive compounds in urine from workers at a chemical plant producing pharmaceuticals and explosives was determined in samples collected after work and after a holiday. Forty-five persons working with aromatic nitro-amino compounds (ANA) showed a statistically significant (p less than 0.01) increase in the exposed samples (1.21 +/- 1.40 mmol/mol creatinine) compared to the unexposed samples (0.56 +/- 0.31 mmol/mol creatinine). No increase in the level of diazo-positive metabolites was found in the 25 workers not exposed to ANA compounds. In a follow-up study, 32 trinitrotoluene (TNT) workers were divided into three exposure categories and seemed to show a dose-dependent increase in the level of urinary diazo-positive metabolites. However, there was a considerable interindividual variation. The method seems suitable for the biological assessment of exposure to ANA compounds--at least on a group level. This may be valuable, especially in situations where significant dermal uptake is expected.

Effect of renal formic acid excretion on urinary calcium and ammonia concentrations

Intragastrically given formic acid (300 mg/kg) caused high urinary formate concentrations in rabbits with continuously decreasing urinary pH up to 30 h after the dose despite the fact that the bulk of the formate in urine was excreted within 15 h. Urinary formic acid inversely correlated to urinary ammonia in 23 workers occupationally exposed to methanol or formic acid so that the delayed urinary acidification could have been caused by the effects of formate on renal ammonia genesis. The urinary excretion of calcium was linearly correlated to the formic acid excretion by the same subjects. The latter effect may have been caused by interferences with the tubular reabsorption mechanisms for the calcium ion.

Urinary thiosulphate as an indicator of exposure to hydrogen sulphide vapour

Urinary thiosulphate analysed as its bromobimane complex by liquid chromatography revealed quantitatively a preceding hydrogen sulphide gas exposure. The highest thiosulphate concentrations were detected 15 h after the exposure. Controls without a contact to sulphides showed low excretion rates of thiosulphate so that exposures clearly below the fatal hydrogen sulphide gas concentrations could be detected. The urinalysis can therefore be used in the occupational health care as well as for forensic ends.

Elevation of urinary hyaluronic acid in Werner's syndrome and progeria

Werner's syndrome and Hutchinson-Gilford progeria syndrome (progeria) are human genetic diseases which may serve as models for the study of premature aging. The basic defects underlying these diseases are unknown. An abnormally high level of urinary hyaluronic acid (HA) excretion has been previously reported in several Werner's and one progeria subject, all from Japan. To determine if a high HA level is a reliable marker for these diseases, we quantitated the urinary excretion of HA in three progeria subjects, one subject with an atypical progeroid syndrome, and a Werner's syndrome subject. Compared to controls, the total urinary HA was found to be markedly increased in the three progeria samples and in the Werner's syndrome sample. These findings support the previous observations indicating elevated HA may be a specific marker for these diseases.