Electronic cigarette solvents, pulmonary irritation, and endothelial dysfunction: role of acetaldehyde and formaldehyde

After more than a decade of electronic cigarette (E-cig) use in the United States, uncertainty persists regarding E-cig use and long-term cardiopulmonary disease risk. As all E-cigs use propylene glycol and vegetable glycerin (PG-VG) and generate abundant saturated aldehydes, mice were exposed by inhalation to PG-VG-derived aerosol, formaldehyde (FA), acetaldehyde (AA), or filtered air. Biomarkers of exposure and cardiopulmonary injury were monitored by mass spectrometry (urine metabolites), radiotelemetry (respiratory reflexes), isometric myography (aorta), and flow cytometry (blood markers). Acute PG-VG exposure significantly affected multiple biomarkers including pulmonary reflex (decreased respiratory rate, -50%), endothelium-dependent relaxation (-61.8 ± 4.2%), decreased WBC (-47 ± 7%), and, increased RBC (+6 ± 1%) and hemoglobin (+4 ± 1%) versus air control group. Notably, FA exposure recapitulated the prominent effects of PG-VG aerosol on pulmonary irritant reflex and endothelial dysfunction, whereas AA exposure did not. To attempt to link PG-VG exposure with FA or AA exposure, urinary formate and acetate levels were measured by GC-MS. Although neither FA nor AA exposure altered excretion of their primary metabolite, formate or acetate, respectively, compared with air-exposed controls, PG-VG aerosol exposure significantly increased post-exposure urinary acetate but not formate. These data suggest that E-cig use may increase cardiopulmonary disease risk independent of the presence of nicotine and/or flavorings. This study indicates that FA levels in tobacco product-derived aerosols should be regulated to levels that do not induce biomarkers of cardiopulmonary harm. There remains a need for reliable biomarkers of exposure to inhaled FA and AA.NEW & NOTEWORTHY Use of electronic cigarettes (E-cig) induces endothelial dysfunction (ED) in healthy humans, yet the specific constituents in E-cig aerosols that contribute to ED are unknown. Our study implicates formaldehyde that is formed in heating of E-cig solvents (propylene glycol, PG; vegetable glycerin, VG). Exposure to formaldehyde or PG-VG-derived aerosol alone stimulated ED in female mice. As ED was independent of nicotine and flavorants, these data reflect a "universal flaw" of E-cigs that use PG-VG.Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/e-cigarettes-aldehydes-and-endothelial-dysfunction/.

A rapid and sensitive fluorescence method for detecting urine formaldehyde in patients with Alzheimer's disease

BACKGROUND

Morning urine formaldehyde concentrations could predict the severe degree of dementia in patients with post-stroke dementia and Alzheimer's disease. However, the routinely available technique of high-performance liquid chromatography (HPLC) for detecting urine formaldehyde requires expensive and sophisticated equipment.

METHODS

We established a fluorescence spectrophotometric method by using a formaldehyde-specific fluorescent probe-NaFA (λex/em = 430/543 nm). As a standard reference method, the same batch of urine samples was analysed by HPLC with a fluorescence detector (λex/em = 346/422 nm). Then we compared the limits of detection and the limits of quantization detected by these two methods and addressed the relationship between urine formaldehyde and human cognitive ability. The Mini-Mental State Examination (MMSE), Clinical Dementia Rating and Activities of Daily Living scale were used to evaluate cognition function in 30 Alzheimer's disease patients and 52 healthy age-matched controls.

RESULTS

Limits of detection and limits of quantization (1.27 and 2.48 μM) of the NaFA probe method were more accurate than Fluo-HPLC (1.52 and 2.91 μM). There was no difference in the detected formaldehyde values within day and day-to-day. Notably, only 3/82 urine formaldehyde concentrations detected by NaFA probe were below zero, while 12/82 of the values analysed by Fluo-HPLC were abnormal. More importantly, there were negatively correlated between urine formaldehyde concentrations detected by NaFA probe and MMSE scores, but positively correlated with Clinical Dementia Rating scores in Alzheimer's disease patients.

CONCLUSIONS

This detecting urine formaldehyde method by NaFA probe was more rapid, sensitive and accurate than Fluo-HPLC.

Potential Adverse Effects of Creatine Supplement on the Kidney in Athletes and Bodybuilders

INTRODUCTION

Nowadays, creatine is one of the most common oral supplements used by professional athletes for boosting their strength and muscle mass. In this review, we collect available experimental and clinical data about renal safety of both short-term and long-term use of creatine.

MATERIALS AND METHODS

Scientific literature was critically searched by keywords "creatine," "renal insufficiency," and "renal dysfunction" and their synonyms in medical databases (Scopus, MEDLINE, EMBase, and ISI Web of Knowledge). Overall, 19 relevant clinical and experimental articles were selected for this review.

RESULTS

Short- and long-term creatine supplementations (range, 5 days to 5 years) with different doses (range, 5 g/d to 30 g/d) had no known significant effects on different studied indexes of kidney function such as glomerular filtration rate at least in healthy athletes and bodybuilders with no underlying kidney diseases. In addition, although short-term (range, 5 days to 2 weeks) high-dose oral creatine supplementation (range, 20 g/d to 0.3 g/kg/d) stimulated the production of methylamine and formaldehyde (as potential cytotoxic metabolites of creatine) in the urine of healthy humans, there was currently no definite clinical evidence about their adverse effects on the kidney function.

CONCLUSIONS

Although creatine supplementation appears to have no detrimental effects on kidney function of individuals without underlying kidney diseases, it seems more advisable to suggest that creatine supplementation not to be used by sportsmen or women with pre-existing kidney disease or those with a potential risk for kidney dysfunction.

Formaldehyde induces diabetes-associated cognitive impairments

Patients with type 2 diabetes mellitus (T2DM) often develop cognitive impairments and have an increased risk of developing Alzheimer's disease. Hyperglycemia is a major characteristic of T2DM, but how elevated glucose levels lead to cognitive decline remains elusive. Here, we report that patients with T2DM and mutations in the formaldehyde (FA)-degrading enzyme aldehyde dehydrogenase 2 ( ALDH2) gene had higher levels of FA and more severe dementia. Injection of FA induced hyperglycemia and cognitive deficits in rats. Ablation of gene expression of ALDH2, the main enzyme to oxidize FA, resulted in abnormally high levels of hippocampal FA, leading to hyperglycemia and cognitive impairments as well as potentiating streptozotocin-induced diabetes development in ALDH2 knockout mice. We found that FA interacts with insulin to form FA-insulin adducts, and these FA-insulin adducts caused insulin deficiency, contributing to memory decline in diabetic rodent models. Reduction of FA by transgenic overexpression of human ALDH2 attenuates hyperglycemia and alleviates cognitive deficits in diabetic mouse models. These findings suggest that excess FA plays a critical role in mediating diabetes-related dementia. Targeting FA and its metabolizing enzyme ALDH2 may be a valid approach for preventing and treating dementia in diabetes mellitus.-Tan, T., Zhang, Y., Luo, W., Lv, J., Han, C., Hamlin, J. N. R., Luo, H., Li, H., Wan, Y., Yang, X., Song, W., Tong, Z. Formaldehyde induces diabetes-associated cognitive impairments.

Pyrenyl carbon nanostructures for ultrasensitive measurements of formaldehyde in urine

Measurement of ultra-low (e.g., parts-per-billion) levels of small-molecule markers in body fluids (e.g., serum, urine, saliva) involves a considerable challenge in view of designing assay strategies with sensitivity and selectivity. Herein we report for the first time an amperometric nano-bioelectrode design that uniquely combines 1-pyrenebutyric acid units pi-pi stacked with carboxylated multiwalled carbon nanotubes on the surface of gold screen printed electrodes for covalent attachment of NAD+ dependent formaldehyde dehydrogenase (FDH). The designed enzyme bioelectrode offered 6 ppb formaldehyde detection in 10-times diluted urine with a wide dynamic range of 10 ppb to 10 ppm. Fourier transform infrared, Raman, and electrochemical impedance spectroscopic characterizations confirmed the successful design of the FDH bioelectrode. Flow injection analysis provided lower detection limit and greater affinity for formaldehyde (apparent KM 9.6 ± 1.2 ppm) when compared with stirred solution method (apparent KM 19.9 ± 4.6 ppm). Selectivity assays revealed that the bioelectrode was selective toward formaldehyde with a moderate cross-reactivity for acetaldehyde (∼25%) and negligible cross-reactivity toward propanaldehyde, acetone, methanol, and ethanol. Formaldehyde is an indoor pollutant, and studies have indicated neurotoxic characteristics and systemic toxic effects of this compound upon chronic and high doses of exposure. Moreover, reported chromatography and mass spectrometry methods identified elevated urine formaldehyde levels in patients with bladder cancer, dementia, and early stages of cognitive impairments compared to healthy people. Results demonstrate that pyrenyl carbon nanostructures-based FDH bioelectrode design represents novelty and simplicity for enzyme-selective electrochemical quantitation of small 30 Da formaldehyde. Broader applicability of the presented approach for other small-molecule markers is feasible that requires only the design of appropriate marker-specific enzyme systems or receptor molecules.

Urine Formaldehyde Predicts Cognitive Impairment in Post-Stroke Dementia and Alzheimer's Disease

Although Alzheimer's disease (AD) was first described over 100 years ago, there is still no suitable biomarker for diagnosing AD in easily collectable samples (e.g., blood plasma, saliva, and urine). Here, we investigated the relationship between morning urine formaldehyde concentration and cognitive impairment in patients with post-stroke dementia (PSD) or AD in this cross-sectional survey for 7 years. Cognitive abilities of the study participants (n = 577, four groups: 231 controls, 61 stroke, 65 PSD, and 220 AD) were assessed by Mini-Mental State Examination (MMSE). Morning urine formaldehyde concentrations were measured by high performance liquid chromatography (HPLC). Gender- and age-matched participants were selected from the four groups (n = 42 in each group). Both semicarbazide-sensitive amine oxidase (SSAO, a formaldehyde-generating enzyme) and formaldehyde levels in the blood and urine were analyzed by using an enzyme-linked immunosorbent assay (ELISA) and HPLC, respectively. We found that morning urine formaldehyde levels were inversely correlated with MMSE scores. The threshold value (the best Cut-Off value) of formaldehyde concentration for predicting cognitive impairment was 0.0418 mM in patients with PSD (Sensitivity: 92.3%; Specificity: 77.1%), and 0.0449 mM in patients with AD (Sensitivity: 94.1%; Specificity: 81.8%), respectively. The results of biochemical analysis revealed that the observed increase in urine formaldehyde resulted from an overexpression of SSAO in the blood. The findings suggest that measuring the concentration of formaldehyde in overnight fasting urine could be used as a potentially noninvasive method for evaluating the likelihood of ensuing cognitive impairment or dementia.

Effects of creatine supplementation along with resistance training on urinary formaldehyde and serum enzymes in wrestlers

BACKGROUND

Formaldehyde is a cytotoxic agent produced from creatine through a metabolic pathway, and in this regard, it has been claimed that creatine supplementation could be cytotoxic. Even though the cytotoxic effects of creatine supplementation have been widely studied, yet little is known about how resistance training can alter these toxic effects. This study aimed to determine the effects of short-term creatine supplementation plus resistance training on the level of urinary formaldehyde and concentrations of serum enzymes in young male wrestlers.

METHODS

In a double-blind design twenty-one subjects were randomized into creatine supplementation (Cr), creatine supplementation plus resistance training (Cr + T) and placebo plus resistance training (Pl + T) groups. Participants ingested creatine (0.3 g/kg/day) or placebo for 7 days. The training protocol consisted of 3 sessions in one week, each session including three sets of 6-9 repetitions at 80-85% of one-repetition maximum for whole-body exercise. Urine and blood samples were collected at baseline and at the end of the supplementation.

RESULTS

Creatine supplementation significantly increased the excretion rate of urinary formaldehyde in the Cr and Cr + T groups by 63.4% and 30.4%, respectively (P<0.05), indicating that resistance training could partially lower this rate by 17.7%. No significant differences were detected in the levels of serum enzymes across time and groups (P>0.05).

CONCLUSIONS

These findings indicate that resistance training may lower the increase of urinary formaldehyde excretion induced by creatine supplementation, suggesting that creatine consumption could be relatively less toxic when combined with resistance training.

[Environmental tobacco smoke--assessment of formaldehyde concentration in urine samples of exposed medicine students]

Environmental Tobacco Smoke (ETS) is ranked as one of the factors of confirmed carcinogenicity to human. It consists of the mixture of smoke exhaled by the smoker as well as the sidestream smoke and contains many times higher concentrations of some toxic substances in comparison to the amount of toxic compounds inhaled by a smoker. From many years the issue of passive smoking has been the subject of many research and still not all of its aspects of affecting human health have been explored. Apart from the tobacco varieties, also diverse additives added during the process of tobacco manufacturing, including particularly carbohydrates, influence the composition of the environmental tobacco smoke. During smoking they can undergo many complex transformations, as a result of which toxic components of the environmental tobacco smoke are formed, carbonyl compounds in particular, like aldehydes. They are marked by a significant chemical reactivity which enables them to modify amino groups of proteins leading to the changes in their structure, biological functions and often antigenicity. Therefore their influence to the human body is the cause of numerous adverse health effects caused by the increase in free radical processes which can constitute to the source of these compounds. Well known representative of this group of xenobiotics is formaldehyde as a compound that reflects well the environmental exposure to carbonyl compounds. The considerable source of this compound is tobacco smoke. Therefore analysis of formaldehyde in body fluids is a valuable biomonitoring tool of exposure to it. The aim of this study was the evaluation of formaldehyde concentration in urine samples of medicine students exposed to ETS. The study material consisted of 149 urine samples of students from School of Medicine with the Division of Dentistry in Zabrze, Medical University of Silesia. The concentration of formaldehyde in urine samples was determined by a spectrophotometric method using the Purpald reagent. To verify the collected questionnaire data regarding exposure to constituents of tobacco smoke, the immuno-enzymatic method was used to determine main nicotine metabolites in tested urine samples. This enabled dividing the investigated students' group into active smokers, passively exposed to tobacco smoke and not exposed. Analysis of obtained results showed that mean concentration of formaldehyde in urine of active smokers (68.45 ± 58.67 µmol/l) and passive smokers (79.23 ± 53.64 µmol/l) were significantly higher in comparison to not exposed students (42.99 ± 30.29 µmol/l). Mean concentrations of formaldehyde in urine samples of active and passive smokers are comparable. The results of our study allow to conclude that passive exposure to tobacco smoke is an equivalent source of exposure to active smoking regarding formaldehyde adverse influence to human. Applied method enables to quick evaluation of formaldehyde concentration in biological samples.

Uric formaldehyde levels are negatively correlated with cognitive abilities in healthy older adults

Recent studies have shown that the abnormal accumulation of endogenous formaldehyde could be a critical factor in age-related cognitive decline. The aim of this study was to estimate the correlation between uric formaldehyde and general cognitive abilities in a community-based elderly population, and to measure the extent and direction in which the correlation varied with demographic characteristics. Using a double-blind design, formaldehyde in human urine was analyzed by high-performance liquid chromatography (n = 604), and general cognitive abilities were measured using the Montreal Cognitive Assessment (MoCA). Demographic characteristics, in terms of age, gender, residential region, and education were taken into consideration. We found that uric formaldehyde levels were inversely correlated with the MoCA score, and the concentration varied with demographic features: higher odds of a high formaldehyde level occurred among the less educated and those living in old urban or rural areas. In cytological experiments, the level of cellular formaldehyde released into the medium increased as SH-SY5Y and BV2 cells were incubated for three days. Formaldehyde in excess impaired the processes of N2a cells and neurites of primary cultured rat hippocampal cells. However, removal of formaldehyde markedly rescued and regenerated the processes of N2a cells. These results demonstrated a negative correlation between the endogenous formaldehyde and general cognitive abilities. High formaldehyde levels could be a risk factor for cognitive impairment in older adults, and could be developed as a non-invasive marker for detection and monitoring of age-related cognitive impairment.

[Biomonitoring of formaldehyde in the urinary samples from the pediatric population in the Irkutsk Region]

Formaldehyde is one of the major pollutants of both ambient and indoors air. Thus, by comparing the concentrations of formaldehyde in ambient air (on study days) and in the air of classes and living rooms, the study has demonstrated that they may be 13.5 and 10.5 times greater than the normal values in the classes and living rooms, respectively. Biomonitoring of formaldehyde in the urinary samples from the pediatric population of the Irkutsk Region as an indicator of its chemical action has revealed the higher average group concentration of the substance in the urinary samples from urban children than that in rural ones (235 children from 6 inhabited localities). A significant correlation has been also found between the levels of formaldehyde in the urine of children (aged 5-10 years) and its concentration in the air of living rooms in the town of Shelekhov.

Determination of formaldehyde in urine by headspace gas chromatography

Formaldehyde is a carcinogen to which humans are exposed daily, but few methods are available to quantify formaldehyde in biological samples. We developed a simple, sensitive and rapid technique for the quantification of formaldehyde in urine by derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine, using a headspace sampler coupled to a gas chromatograph equipped with an electron capture detector. The detection limit was 1.08 microg/L. The overall recovery of formaldehyde spiked in urine was 99%. The concentration of formaldehyde in urine obtained from healthy volunteers ranged from 56.85 to 144.57 microg/L. This method can be used successfully to measure formaldehyde in urine.

N-Methylenvaline in a group of subjects occupationally exposed to formaldehyde

Aim of this pilot study was to correlate the human exposure to formaldehyde (F) with N-methylenvaline, a molecular adduct formed by addiction of F to the N-terminal valine in hemoglobin. A group of 21 subjects employed in a plywood factory and a laminate factory, and occupationally exposed to F, together with a group of 30 controls, were recruited as volunteers to test this biomarker. Each subject received a questionnaire and a passive personal F sampler. Exposure to F vapors and occurrence of N-methylenvaline in blood were measured. Integrated F concentrations always proved lower than threshold limit value as a ceiling (TLV-TWA) (0.37 mg/m(3), 0.3 ppm). N-Methylenvaline distribution in blood, as measured by GC/MS upon derivatization, showed direct positive relationship to F exposure, with r=0.465. Prevalence of the molecular adduct expressed in nmol/g of globin was significantly higher in the exposed group (p<0.04) than in the control group. However, the N-methylenvaline marker was unable to provide significant distinction between the subjects exposed to F through tobacco smoke habit and the non smokers. Despite this interference, in this pilot study the usefulness of N-methylenvaline as a biomarker for testing occupational exposure to F was demonstrated.

Effect of oral creatine supplementation on urinary methylamine, formaldehyde, and formate

PURPOSE

It has been claimed that oral creatine supplementation might have potential cytotoxic effects on healthy consumers by increasing the production of methylamine and formaldehyde. Despite this allegation, there has been no scientific evidence obtained in humans to sustain or disprove such a detrimental effect of this widely used ergogenic substance.

METHODS

Twenty young healthy men ingested 21 g of creatine monohydrate daily for 14 consecutive days. Venous blood samples and 24-h urine were collected before and after the 14th day of supplementation. Creatine and creatinine were analyzed in plasma and urine, and methylamine, formaldehyde, and formate were determined in 24-h urine samples.

RESULTS

Oral creatine supplementation increased plasma creatine content 7.2-fold (P < 0.001) and urine output 141-fold (P < 0.001) with no effect on creatinine levels. Twenty-four-hour urine excretion of methylamine and formaldehyde increased, respectively, 9.2-fold (P = 0.001) and 4.5-fold (P = 0.002) after creatine feeding, with no increase in urinary albumin output (9.78 +/- 1.93 mg x 24 h(-1) before, 6.97 +/- 1.15 mg x 24 h(-1) creatine feeding).

CONCLUSION

This investigation shows that short-term, high-dose oral creatine supplementation enhances the excretion of potential cytotoxic compounds, but does not have any detrimental effects on kidney permeability. This provides indirect evidence of the absence of microangiopathy in renal glomeruli.

Selective measurement of HCHO in urine using direct liquid-phase fluorimetric analysis

Quantification of formaldehyde (HCHO) in urine was recently shown to be a promising tool in the investigation of cancer, particularly bladder cancer. Development of a low-maintenance, inexpensive and rapid analyzer for HCHO in urine would greatly facilitate future research and the potential diagnosis of bladder cancer. We examine here the application of an off-the-shelf system, originally designed for gas-phase atmospheric monitoring of HCHO, for the quantification of HCHO in urine. Under strict dietary protocols, e.g., avoidance of foods rich in free or chemically bound HCHO, an increase in HCHO in urine is an indirect indicator of cancer in the urogenital system. The concentration of HCHO in urine samples from an individual over a several-month period was determined, with a range from 39 to 1400μM and a mean of 600μM. The limit of detection for the present method was 0.1μM. The proposed technique provides a direct, low-cost and greatly simplified analytical method for the quantification of HCHO in urine compared to other available techniques.

A novel sensitive high-performance liquid chromatography/electrochemical procedure for measuring formaldehyde produced from oxidative deamination of methylamine and in biological samples

Formaldehyde is a well-known environmental toxic hazard. It is also a product of oxidative deamination of methylamine catalyzed by semicarbazide-sensitive amine oxidase (SSAO). Increased SSAO-mediated deamination has been implicated in some pathophysiological conditions, such as diabetic complications. The measurement of formaldehyde in the enzymatic reactions and in vivo production using conventional methods was not straightforward due to limitations of selectivity and sensitivity. A novel high-performance liquid chromatography (HPLC)/electrochemical procedure for the measurement of formaldehyde has been developed. The measurement is based on the formation of adducts between formaldehyde and dopamine. These adducts can be selectively purified and concentrated using a batch method of alumina absorption, separated by HPLC, and electrochemically quantified. The method is highly selective and substantially more sensitive, i.e., detection of picomole levels of formaldehyde, than the conventional methods. The procedure not only facilitates the assessment of SSAO activity in vitro but also is useful for assessing formaldehyde in tissues and biological fluids.

HPLC analysis of metabolically produced formaldehyde

Radiolabelled (-)-deprenyl is orally administered to rats, and urinary elimination of radiolabelled formaldehyde is detected. The separation is performed using high-performance liquid chromatography on octadecyl-silica stationary phase. Both the radioactivity and the UV absorbance of the dinitrophenylhydrazine formaldehyde peak are determined. Formaldehyde generation takes place by N-demethylation. Low levels of formaldehyde may have a beneficial role in counterbalancing the oxidative stress of the everyday person's life.

[Diagnosis of formaldehyde allergy]

Exposure to small-dose environmental agents is a risk factor of immunopathological reactions. The levels of formaldehyde-specific IgE were comparatively analyzed in 50 children of whom 25 live in the area exposed to formaldehyde. Children with varying respiratory allergic reactions comprised a study group. To identify allergen-specific IgE, the authors used a method that determined formaldehyde antibodies by using the tested allergen (formaldehyde on the paper). There were significant group-specific differences in the levels of formaldehyde antibodies (3.8 times higher in the study group than in the controls). Combined therapy substantially reduced specific IgE whose levels returned to the levels observed in the controls. The findings may recommend the use of this test for the diagnosis of immune-depended abnormalities and the evaluation of their effective treatment.

Oxidative mechanisms in the toxicity of chromium and cadmium ions

Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of the oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities.

Formaldehyde generation by N-demethylation

Microsomal oxidation of exogenic compounds yields efferent metabolites with small molecular size. N-demethylation results in formaldehyde generation in addition to the nor-compound. Interesting changes in the level of formaldehyde elimination were observed after a single dose of either ( )-deprenyl or (+)-deprenyl. Urine elimination of the generated formaldehyde was determined using thin-layer chromatography after derivatization with dimedone.

Simultaneous determination of formaldehyde and methylglyoxal in urine: involvement of semicarbazide-sensitive amine oxidase-mediated deamination in diabetic complications

The deamination of methylamine and aminoacetone by semicarbazide-sensitive amine oxidase (SSAO) produces formaldehyde and methylglyoxal, respectively, which have been presumed to be involved in diabetic complications. A high-performance liquid chromatography procedure using 2,4-dinitrophenylhydrazine (DNPH) as a derivatizing agent is developed to determine endogenous formaldehyde, methylglyoxal, malondialdehyde, and acetaldehyde. The devised DNPH method is sensitive enough to analyze aldehyde levels in urine. An increase in the excretion of formaldehyde, methylglyoxal, and malondialdehyde is confirmed in streptozotocin-induced diabetic rats. Following the chronic administration of methylamine, the urinary levels of both formaldehyde and malondialdehyde (a product from lipid peroxidation) are found to be substantially increased. A potent selective SSAO inhibitor, (E)-2-(4-fluorophenethyl)-3-fluoroallylamine hydrochloride (MDL-72974A), reduced the formation of formaldehyde, methylglyoxal, and malondialdehyde. The increase of the cytotoxic aldehyde levels as a result of increased SSAO-mediated deamination may occur in some pathological conditions.

Assessment of total exposure to phenol-formaldehyde resin glue in plywood manufacturing

OBJECTIVE

Respiratory and dermal exposure to phenol-formaldehyde resin-glue components used in plywood manufacturing were assessed.

METHODS

Formaldehyde and phenol were monitored in the workplace air. Formaldehyde was measured both in the breathing zones of the workers and at stationary sampling sites. Phenol was used as a marker agent for dermal exposure due to its near-nonvolatility at the temperatures occurring during the present study and to its ready absorption through the skin, causing systemic exposure in addition to local skin rashes. Sampling and analytical methods were developed to measure the dermal exposure to phenol. Sampling was accomplished with whole-body dosimetry using Tyvek coveralls and cotton gloves. In addition, a liquid chromatography method was developed for the analysis of phenol from dermal exposure samples.

RESULTS

As expected, formaldehyde was noted to be the major compound causing respiratory exposure. When exposure assessment was done on the basis of air samples collected both at stationary sampling sites and in the breathing zones of the workers the agreement between the results obtained was good. The dermal sampling revealed that the workers were exposed to phenol, but the risk for toxic effects was slight due to the low concentrations of urinary phenol.

CONCLUSIONS

We conclude that it is possible to use the stationary sampling method for the assessment of respiratory exposure in a plywood factory instead of the usually more complicated breathing-zone sampling. This study also demonstrates the importance of taking dermal exposure into account, at least due to the ability of the resins to cause skin rashes, in assessment of the exposure to chemicals in plywood manufacturing.

Deamination of methylamine and aminoacetone increases aldehydes and oxidative stress in rats

Semicarbazide-sensitive amine oxidase (SSAO)-mediated deamination of methylamine and aminoacetone in vitro produces carbonyl compounds, such as formaldehyde and methylglyoxal, which have been proposed to be cytotoxic and may be responsible for some pathological conditions. An HPLC procedure was developed to assess different aldehydes, which were derivatized with 2,4-dinitrophenylhydrazine (DNPH). We have demonstrated in vivo deamination of methylamine and aminoacetone by examining the excretion of formaldehyde and methylglyoxal, respectively, in rats. Following chronic administration of methylamine, the urinary level of malondialdehyde (MDA), an end product of lipid peroxidation, was also found to be substantially increased. A selective SSAO inhibitor blocked the increase of MDA. The results support the idea that increased SSAO-mediated deamination of methylamine and aminoacetone can be a potential cytotoxic risk factor.

Subchronic effects of smokeless tobacco extract (STE) on hepatic lipid peroxidation, DNA damage and excretion of urinary metabolites in rats

The oral use of moist smokeless tobacco products (snuff) is causally associated with cancer of the mouth, lip, nasal cavities, esophagus and gut. The mechanism by which smokeless tobacco constituents produce genetic and tissue damage is not known. Recent studies in our laboratories have shown that an aqueous extract of smokeless tobacco (STE) activates macrophages with the resultant production of reactive oxygen species (ROS), including nitric oxide. Furthermore, the administration of acute doses of STE (125-500 mg/kg) to rats induces dose dependent increases in mitochondrial and microsomal lipid peroxidation, enhances DNA single strand breaks, and significantly increases the urinary excretion of the lipid metabolites malondialdehyde, formaldehyde, acetaldehyde and acetone. Since the use of tobacco is a chronic process, the effects of an aqueous extract of STE in rats following low dose exposure were examined. Female Sprague-Dawley rats were treated orally with 25 mg STE/kg every other day for 105 days. The effects of subchronic treatment of STE on hepatic microsomal and mitochondrial lipid peroxidation and the incidence of hepatic nuclear DNA damage were assessed. Lipid peroxidation increased 1.4- to 3.3-fold in hepatic mitochondria and microsome with STE treatment between 0 and 105 days with respect to control animals while hepatic DNA single strand breaks increased up to 3.4-fold. Maximum increases in lipid peroxidation and DNA single strand breaks occurred between 75 and 90 days of treatment. Urinary excretion of the four lipid metabolites malondialdehyde, formaldehyde, acetaldehyde and acetone was monitored by high pressure liquid chromatography (HPLC) with maximum increases being observed between 60 and 75 days of treatment. The results clearly indicate that low dose subchronic administration of STE induces an oxidative stress resulting in tissue damaging effects which may contribute to the toxicity and carcinogenicity of STE.

Induction of oxidative stress by chronic administration of sodium dichromate [chromium VI] and cadmium chloride [cadmium II] to rats

Recent studies have demonstrated that both chromium (VI) and cadmium (II) induce an oxidative stress, as determined by increased hepatic lipid peroxidation, hepatic glutathione depletion, hepatic nuclear DNA damage, and excretion of urinary lipid metabolites. However, whether chronic exposure to low levels of Cr(VI) and Cd(II) will produce an oxidative stress is not shown. The effects of oral, low (0.05 LD50) doses of sodium dichromate [Cr(VI); 2.5 mg/kg/d] and cadmium chloride [Cd(II); 4.4 mg/kg/d] in water on hepatic and brain mitochondrial and microsomal lipid peroxidation, excretion of urinary lipid metabolites including malondialdehyde, formaldehyde, acetaldehyde and acetone, and hepatic nuclear DNA-single strand breaks (SSB) were examined in female Sprague-Dawley rats over a period of 120 d. The animals were treated daily using an intragastric feeding needle. Maximum increases in hepatic and brain lipid peroxidation were observed between 60 and 75 d of treatment with both cations. Following Cr(VI) administration for 75 d, maximum increases in the urinary excretion of malondialdehyde, formaldehyde, acetaldehyde, and acetone were 2.1-, 1.8-, 2.1-, and 2.1-fold, respectively, while under the same conditions involving Cd(II) administration approximately 1.8-, 1.5-, 1.9-, and 1.5-fold increases were observed, respectively, as compared to control values. Following administration of Cr(VI) and Cd(II) for 75 d, approximately 2.4- and 3.8-fold increases in hepatic nuclear DNA-SSB were observed, respectively, while approximately 1.3- and 2.0-fold increases in brain nuclear DNA-SSB were observed, respectively. The results clearly indicate that low dose chronic administration of sodium dichromate and cadmium chloride induces an oxidative stress resulting in tissue damaging effects that may contribute to the toxicity and carcinogenicity of these two cations.

Oxidative stress induced by chronic administration of sodium dichromate [Cr(VI)] to rats

Chromium occurs in the workplace primarily in the valence forms Cr(III) and Cr(VI). Recent studies have demonstrated that sodium dichromate [Cr(VI)] induces greater oxidative stress as compared with Cr(III), as indicated by the production of reactive oxygen species by peritoneal macrophages and hepatic mitochondria and microsomes, and enhanced excretion of urinary lipid metabolites and hepatic DNA-single strand breaks (SSB) following acute oral administration of Cr(III) and Cr(VI). We have therefore examined the chronic effects of sodium dichromate dihydrate [Cr(VI); 10 mg (33.56 mumol)/kg/day] on hepatic mitochondrial and microsomal lipid peroxidation, enhanced excretion of urinary lipid metabolites including malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT), acetone (ACON) and propionaldehyde (PROP), and hepatic DNA damage over a period of 90 days. The maximal increases in hepatic lipid peroxidation and DNA damage were observed at approximately 45 days of treatment. Maximum increases in the urinary excretion of MDA, FA, ACT, ACON and PROP were 3.2-, 2.6-, 4.1-, 3.3- and 2.1-fold, respectively, while a 5.2-fold increase in DNA-SSB was observed. The results clearly indicate that chronic sodium dichromate administration induces oxidative stress resulting in tissue damaging effects which may contribute to the toxicity and carcinogenicity of hexavalent chromium.

Chromium-induced excretion of urinary lipid metabolites, DNA damage, nitric oxide production, and generation of reactive oxygen species in Sprague-Dawley rats

Chromium and its salts induce cytotoxicity and mutagenesis, and vitamin E has been reported to attenuate chromate-induced cytotoxicity. These observations suggest that chromium produces reactive oxygen species which may mediate many of the untoward effects of chromium. We have therefore examined and compared the effects of Cr(III) (chromium chloride hexahydrate) and Cr(VI) (sodium dichromate) following single oral doses (0.50 LD50) on the production of reactive oxygen species by peritoneal macrophages, and hepatic mitochondria and microsomes in rats. The effects of Cr(III) and Cr(VI) on hepatic mitochondrial and microsomal lipid peroxidation and enhanced excretion of urinary lipid metabolites as well as the incidence of hepatic nuclear DNA damage and nitric oxide (NO) production were also examined. Increases in lipid peroxidation of 1.8- and 2.2-fold occurred in hepatic mitochondria and microsomes, respectively, 48 hr after the oral administration of 25 mg Cr(VI)/kg, while increases of 1.2- and 1.4-fold, respectively, were observed after 895 mg Cr(III)/kg. The urinary excretion of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) were determined at 0-96 hr after Cr administration. Between 48 and 72 hr post-treatment, maximal excretion of the four urinary lipid metabolites was observed with increases of 1.5- to 5.4-fold in Cr(VI) treated rats. Peritoneal macrophages from Cr(VI) treated animals 48 hr after treatment resulted in 1.4- and 3.6-fold increases in chemiluminescence and iodonitrotetrazolium reduction, indicating enhanced production of superoxide anion, while macrophages from Cr(III) treated animals showed negligible increases. Increases in DNA single strand breaks of 1.7-fold and 1.5-fold were observed following administration of Cr(VI) and Cr(III), respectively, at 48 hr post-treatment. Enhanced production of NO by peritoneal exudate cells (primarily macrophages) was monitored following Cr(VI) administration at both 24 and 48 hr post-treatment with enhanced production of NO being observed at both timepoints. The results indicate that both Cr(VI) and Cr(III) induce an oxidative stress at equitoxic doses, while Cr(VI) induces greater oxidative stress in rats as compared with Cr(III) treated animals.

Adriamycin-induced hepatic and myocardial lipid peroxidation and DNA damage, and enhanced excretion of urinary lipid metabolites in rats

Adriamycin produces clinically useful responses in a variety of human cancers including lymphomas, leukemias, and solid tumors. However, the toxicity of adriamycin has limited its usefulness. Iron-catalyzed free radical reactions as the peroxidation of membrane lipids, inactivation of critical enzymes, and the inhibition of DNA, RNA and protein synthesis in heart, liver and kidney have been implicated in the toxicity of adriamycin. In order to further assess the role of oxidative stress in the toxicity of adriamycin, the effects of adriamycin were examined on the urinary excretion of lipid metabolites at 0, 6, 12, 24, 48 and 72 h post-treatment, and on myocardial and hepatic lipid peroxidation and nuclear DNA single strand breaks at 24 h post-treatment following single oral and intravenous (i.v.) doses of 10 mg/kg adriamycin. Urinary malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) excretion was significantly increased at all time points examined. Following the oral administration of adriamycin, maximum excretion of MDA, FA, ACT and ACON of 6.2-, 2.7-, 3.7- and 2.2-fold relative to control values, respectively, occurred 24 h after treatment. However, following the i.v. administration of adriamycin, greatest increases in excretion of MDA, FA and ACT reaching 6.9-, 3.3- and 6.3-fold relative to control values, respectively, were observed 6 h after treatment, while the greatest increase in ACON excretion of 4.2-fold relative to control values occurred 12 h post-treatment. Following oral and i.v. administration of adriamycin, significant increases were observed in myocardial and hepatic lipid peroxidation in mitochondrial and microsomal membranes, and myocardial and hepatic nuclei DNA single strand breaks 24 h after treatment. The results indicate that adriamycin administration induces myocardial and hepatic lipid peroxidation which may be responsible for enhanced excretion of urinary lipid metabolites as a result of membrane damage, and also induces enhanced DNA damage. These effects may be due to adriamycin-induced production of reactive oxygen species.

Excretion of malondialdehyde, formaldehyde, acetaldehyde, acetone and methyl ethyl ketone in the urine of rats given an acute dose of malondialdehyde

A high pressure liquid chromatographic system (HPLC) has recently been developed for the simultaneous detection of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON). We have examined the urinary excretion of these four lipid metabolites in the urine of rats following the acute oral administration of MDA (158 mg/kg body weight). During the first 12 h, increases in the urinary excretion of MDA and ACT of approximately 192- and 70-fold, respectively, were observed. The urinary excretion of both MDA and ACT decreased thereafter. An increase in FA excretion was observed only 12-24 h after MDA administration. A significant decrease in ACON relative to control values was observed 12-48 h after MDA treatment. Two new peaks were present in the HPLC chromatograms of urine samples 0-24 h after MDA administration. Both peaks were shown to be due to methyl ethyl ketone (MEK) which appears to be formed as a result of MDA metabolism. The results demonstrate that orally administered MDA is rapidly excreted in the urine, and alters the metabolism and excretion of other lipid metabolites.

Detection of paraquat-induced in vivo lipid peroxidation by gas chromatography/mass spectrometry and high-pressure liquid chromatography

The cyclic oxidation-reduction of paraquat results in the formation of oxygen free radicals, which are believed to mediate the toxic manifestations of this herbicide. Because of paraquat's profound effects on lipid peroxidation, the effect of oral administration of 75 mg paraquat/kg to rats has been examined on the urinary excretion of the lipid metabolites malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT), and acetone (ACON) over 48 hours post-treatment. The urinary metabolites were identified by gas chromatography/mass spectrometry and quantitated by high-pressure liquid chromatography. Time-dependent increases in the urinary excretion of the four metabolites were observed after paraquat administration. Over the 48 hours of the study, the paraquat-induced urinary excretion of MDA, FA, ACT, and ACON increased by approximately 218, 155, 331, and 995%, respectively, relative to control animals. The data were expressed in nmol/kg body weight/4.5 h. The results clearly demonstrate that paraquat increases the urinary excretion of four lipid metabolites, which may have widespread applicability as biomarkers of altered lipid metabolism in disease states and cases of exposure to environmental pollutants and xenobiotics that induce enhanced lipid peroxidation.

Carbon-tetrachloride-induced urinary excretion of formaldehyde, malondialdehyde, acetaldehyde and acetone in rats

Previous studies have demonstrated that the hepatotoxin carbon tetrachloride rapidly promotes lipid peroxidation and inhibits microsomal calcium sequestration, microsomal glucose-6-phosphatase activity and cytochrome P-450. Due to its profound effects on lipid peroxidation, we have examined the oral administration of 2.5 ml/kg carbon tetrachloride on the urinary excretion of the lipid metabolites formaldehyde, malondialdehyde, acetaldehyde and acetone. Urine samples were collected up to 48 h after treatment. The urinary metabolites were identified and quantitated by gas chromatography-mass spectrometry and high-pressure liquid chromatography. Time-dependent increases in the urinary excretion of the four metabolites were observed after carbon tetrachloride administration. At 48 h after treatment, the increases in the excretion of malondialdehyde, formaldehyde, acetaldehyde and acetone were approximately 55, 78, 57 and 268%, respectively, relative to control values. The data were expressed in nanomoles per kilogram body weight per 4.5 h. The results clearly demonstrate that carbon tetrachloride increases the urinary excretion of four lipid metabolites which may serve as noninvasive biomarkers of xenobiotic-induced lipid peroxidation.

Protective effects of antioxidants against endrin-induced hepatic lipid peroxidation, DNA damage, and excretion of urinary lipid metabolites

Oxidative stress is believed to play a pivotal role in endrin-induced hepatic and neurologic toxicity. Therefore, the effects of the antioxidants vitamin E succinate and ellagic acid have been examined on hepatic lipid peroxidation, DNA single-strand breaks (SSB), and the urinary excretion of lipid metabolites following an acute oral dose of 4.5 mg endrin/kg. Groups of rats were pretreated with 100 mg/kg vitamin E succinate for 3 d followed by 40 mg/kg on day 4, or 6.0 mg ellagic acid/kg for 3 d p.o. followed by 3.0 mg/kg on day 4 or the vehicle. Endrin was administered p.o. on day 4 2 hr after treatment with the antioxidant. All animals were killed 24 h after endrin administration. Vitamin E succinate pretreatment decreased the endrin-induced increase in hepatic mitochondrial and microsomal lipid peroxidation by approximately 60% and 40%, respectively. Ellagic acid pretreatment reduced the endrin-induced increased in mitochondrial and microsomal lipid peroxidation by approximately 76 and 79%, respectively. Both vitamin E succinate and ellagic acid alone produced small but nonsignificant decreases in hepatic mitochondrial and microsomal lipid peroxidation. A 3.3-fold increase in the incidence of hepatic nuclear DNA single-strand breaks was observed 24 h after endrin administration. Pretreatment of rats with vitamin E succinate, vitamin E, and ellagic acid decreased endrin-induced DNA-SSB by approximately 47%, 22%, and 21%, respectively. Pretreatment of rats with vitamin E succinate decreased the endrin-induced increase in the urinary excretion of malondialdehyde, acetaldehyde, formaldehyde, and acetone by approximately 68, 65, 70, and 55%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of carbon tetrachloride, menadione, and paraquat on the urinary excretion of malondialdehyde, formaldehyde, acetaldehyde, and acetone in rats

Excretions of the lipid peroxidation products, formaldehyde (FA), acetaldehyde (ACT), malondialdehyde (MDA), and acetone (ACON), were simultaneously identified and quantitated in the urine of female Sprague-Dawley rats by gas chromatography-mass spectroscopy (GC-MS) and high pressure liquid chromatography (HPLC) following the acute administration of carbon tetrachloride, a model alkylating agent that does not induce glutathione depletion, and the redox cycling compounds paraquat and menadione. All three xenobiotics are well-known inducers of oxidative stress. Oxidative stress was induced by oral administration of single doses of 2.5 mL of carbon tetrachloride/kg, 60 mg menadione/kg, and 75 mg paraquat/kg. These doses are approximately 50% of the LD50's for the three xenobiotics. Urinary excretion of FA, ACT, MDA, and ACON increased relative to control animals following treatment with all xenobiotics. Over the 48 hours of the study, the greatest increases in the excretion of MDA, FA, ACT, and ACON occurred after paraquat administration, with increases of approximately 2.7-, 2.6-, 4.3-, and 11.0-fold, respectively. This technique may have wide-spread applicability as an effective biomarker for investigating altered lipid metabolism in disease states and exposure to environmental pollutants/xenobiotics.

Excretion of malondialdehyde, formaldehyde, acetaldehyde and acetone in the urine of rats following acute and chronic administration of ethanol

Recent studies have shown that xenobiotics which induce oxidative stress result in an increased production and excretion of acetaldehyde (ACT), formaldehyde (FA), acetone (ACON) and malondialdehyde (MDA) in the urine of rats. We have therefore examined the effect of acute and chronic ethanol administration on the excretion of these four lipid metabolites in female Sprague-Dawley rats. Urine samples were collected over dry ice for 6 hr time periods. Aliquots of urine were derivatized with 2,4-dinitrophenylhydrazine HCl, and extracted with n-pentane. High pressure lipid chromatogrpahy (HPLC) was used to quantitate and the hydrazones of the four lipid metabolite products. Following a single, oral, acute dose of 5 g ethanol/kg, urinary excretion of ACT increased approximately 5.8-fold from 6 to 12 hr posttreatment, and decreased thereafter. FA excretion decreased by approximately 50% from 0 to 12 hr, returned to control values in the 18-24 hr urine samples, and was 1.3-fold greater than control values at 42-48 hr. ACON increased 3.1-fold over control values from 0 to 30 hr and remained elevated throughout the remaining 18 hr of the study. The excretion of MDA increased approximately 1.5-fold from 18 to 36 hr, then remained constant through the 48 hr time point. In a separate series of experiments, a chronic oral dose of 0.5 g ethanol/kg was administered to rats for 10 consecutive days and the urinary excretion of the lipid metabolites MDA, FA, ACT and ACON was examined for 11 days, beginning with the first day of ethanol administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of urine pH and ascorbic acid on the rate of conversion of methenamine to formaldehyde

The kinetics of conversion of methenamine to the active form formaldehyde were studied in pooled urine samples at 37 degrees in the pH range 4.9-6.5. Using a method for the determination of both formaldehyde and unhydrolyzed methenamine, the rate of formaldehyde formation in urine was found to be apparent first order and was pH dependent. Bactericidal concentrations of formaldehyde (> 28 micrograms ml-1) were achieved in 3 h in urine of pH 6.0 containing methenamine at 750 micrograms ml-1. There was no difference in the in vitro rate of conversion of methenamine to formaldehyde between the urine collected from normal subjects and the urine from subjects administered ascorbic acid. The rates of degradation of the mandelate and hippurate salts in buffer systems of various pH values did not differ significantly from those of methenamine base in urine adjusted to the same pH. The half-life of methenamine conversion to formaldehyde increased approximately 20 times from 20 h at pH 5.0 to about 400 h at pH 6.5. The data suggest that unless the urine is maintained below pH 6 only a small fraction of methenamine would be converted daily to formaldehyde and, thus, may explain the need for large doses of this drug in patients.

Endrin-induced urinary excretion of formaldehyde, acetaldehyde, malondialdehyde and acetone in rats

Previous studies have shown that endrin induces an oxidative stress in rats as demonstrated by an increase in hepatic lipid peroxidation, a decrease in glutathione content and a decrease in the activity in selenium-dependent glutathione peroxidase. We have therefore examined the effects of orally administering 1.5, 3.0, 4.5 and 6.0 mg endrin/kg on the urinary excretion of the lipid metabolites formaldehyde, malondialdehyde, acetaldehyde and acetone. The simultaneous determination of these four lipid metabolites may be a useful biomarker for assessing exposure to xenobiotics which induce an oxidative stress and enhanced lipid peroxidation. Urine samples were collected up to 72 h post-treatment. The identities of the lipid metabolites were confirmed by gas chromatography-mass spectroscopy, while the 2,4-dinitrophenylhydrazine derivatives of these metabolic products were quantitated by high pressure liquid chromatography. Maximum increases in the excretion of the four lipid metabolites occurred at approx. 24 h post-treatment at all doses with no significant increases in excretion occurring thereafter. The maximum increases in excretion of malondialdehyde, formaldehyde, acetaldehyde and acetone were approx. 160%, 93%, 121% and 162%, respectively, relative to control values. Seventy-two hours after endrin administration, the liver weight/body weight and spleen weight/body weight ratios significantly increased while the thymus weight/body weight ratio markedly decreased. The results demonstrate that endrin induces dose- and time-dependent alterations in lipid metabolism with the enhanced excretion of specific metabolic products in the urine.

Excretion of formaldehyde, malondialdehyde, acetaldehyde and acetone in the urine of rats in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin, paraquat, endrin and carbon tetrachloride

Formaldehyde (FA), acetaldehyde (ACT), malondialdehyde (MDA) and acetone (ACON) were simultaneously identified in urine, and their excretion quantitated in response to chemically induced oxidative stress. Urine samples of female Sprague-Dawley rats were collected over dry ice and derivatized with 2,4-dinitrophenylhydrazine. The hydrazones of the four lipid metabolic products were quantitated by high-performance liquid chromatography on a Waters 10-microns mu-Bondapak C18 column. The identities of FA, ACT, MDA and ACON in urine were confirmed by gas chromatography-mass spectrometry. An oxidative stress was induced by orally administering 100 micrograms/kg 2,3,7,8-tetrachlorodibenzo-p-dioxin, 75 mg/kg paraquat, 6 mg/kg endrin or 2.5 ml/kg carbon tetrachloride to rats. Urinary excretion of FA, ACT, MDA and ACON increased relative to control animals 24 h after treatment with all xenobiotics. The system has wide-spread applicability to the investigation of altered lipid metabolism in disease states and exposure to environmental pollutants.

Systemic distribution of 14C-labeled formaldehyde applied in the root canal following pulpectomy

The systemic distribution of 14C-labeled formaldehyde which had been placed in the root canals of the canines of cats following pulpectomies was studied using liquid scintillation counting and wholebody autoradiographic technique. Radioactive 14C which had been placed in the canals was found in the plasma 30 min after the root canal procedure. The recovery of systemic 14C radioactivity increased with time. In addition, it seemed that approximately 3% of the dose placed in the teeth was excreted in the urine within 36 h. Whole-body autoradiograms indicated extensive concentration of 14C radioactivity in tissues other than those analyzed with the liquid scintillation technique.

Separation and quantitation of methenamine in urine by ion-pair extraction

An ion-pair extraction technique is described for separating methenamine, a urinary tract antibacterial agent, from formaldehyde in human urine samples. Separation conditions are developed from extraction constants for the methenamine-bromocresol green ion-pair. The technique involves adsorption of the ion-pair onto a silica cartridge and elution with methylene chloride:1-pentanol (95:5). Methenamine is freed from the ion-pair by the addition of excess tetrabutylammonium iodide and converted to formaldehyde (determined spectrophotometrically) by reaction with ammonia and acetylacetone. Linear standard plots were obtained from urine containing methenamine which was diluted to 10-160 micrograms/mL. The lower limit of detection was 6 micrograms/mL of methenamine. Absolute recovery from urine was greater than or equal to 94.5%. The precision (CV) of detection of methenamine in the presence of formaldehyde was less than 2%, and less than or equal to 4.5% for the detection of formaldehyde in the presence of methenamine. No interferences were noted. The applicability of the method was demonstrated by analysis of human urine levels of both methenamine and formaldehyde following oral administration of a methenamine salt to a volunteer.

Percutaneous absorption of formaldehyde in rats

As formaldehyde is used as a preservative in cosmetic products, its dermal absorption from an O/W-cream was studied using rats. [14C]Formaldehyde as a tracer, together with non-labelled formaldehyde, was incorporated into a cream at a total concentration of 0.1%. Approx. 5% of the applied radioactivity was absorbed percutaneously within 48 h. Higher values were not found under occlusive conditions. The labelled substance was excreted primarily in urine and exhaled air. Further radioactivity was found in the carcass. Based on these results, a rough approximation was attempted of the amount of formaldehyde which could penetrate human skin after the application of a formaldehyde-containing cosmetic.

Methenamine mandelate with acidification: an effective urinary antiseptic in patients with neurogenic bladder

We studied the effectiveness of methenamine mandelate in preventing urinary tract infection in patients with neurogenic bladder dysfunction who were in a program of intermittent catheterization and bladder retraining. Nine of 17 patients (53%) became infected while receiving the drug, whereas 19 of 22 patients (86%) in a placebo group became infected during the trial. The difference in infection rates was statistically significant (P less than 0.02) and resulted primarily from the absence of gram-positive cocci and Pseudomonas species in the drug group.

Effect of urinary acidifiers on formaldehyde concentration and efficacy with methenamine therapy

Twenty-seven patients with indwelling urinary catheters and chronic bacteriuria were studied for methenamine efficacy. In a crossover fashion, each patient received methenamine mandelate granules 4 g/day alone, with ascorbic acid 4 g/day, and with ascorbic acid 4 g/day plus cranberry cocktail one 1/day. Proteus vulgaris, Pseudomonas aeruginosa, and E. coli were the common pathogens. Urinary acidifiers had no significant effect on mean urine pH, however, high urinary formaldehyde concentrations were associated with the use of ascorbic acid. Bacteriocidal formaldehyde levels were more frequently present in patients with acidic urine pH than those with alkaline pH. Although ascorbic acid increased formaldehyde levels, additional cranberry cocktail had no further effect. Despite higher formaldehyde levels, urine culture results were positive in most cases with or without urine acidification. Methenamine therapy may be of limited value in asymptomatic chronic bacteriuric patients with indwelling catheters.

Urinary excretion of methenamine and formaldehyde: evaluation of 10 methenamine products in humans

The urinary excretion of both methenamine and formaldehyde was measured for 48 hr after the oral administration of 10 different methenamine products to 10 human subjects in a crossover study. The following dosage forms were evaluated: a tablet of methenamine base, a methenamine hippurate tablet, and eight products containing methenamine mandelate, including six enteric-coated tablets, a suspension, and a granule dosage form. The nonenteric-coated dosage forms were absorbed more rapidly, based on maximum excretion rates that occurred within 3 hr after dosing. The enteric-coated tablets, which were designed not to release methenamine until reaching the intestinal tract, exhibited maximum excretion rates that did not occur until 7-17 hr after dosing. There were no significant differences (p greater than 0.05) among products in terms of total excretion of free formaldehyde in the urine. However, large differences (p less than 0.05) were noted among products for urinary recovery of total methenamine, with the amount of administered dose recovered ranging from 16 to 83%.

Predictability of methenamine efficacy based on type of urinary pathogen and pH

This study involved 27 geriatric patients with asymptomatic chronic bacteriuria; all had indwelling Foley catheters. The treatment regimens (daily oral dosage) were: methenamine mandelate (MM) granules, 4 gm; MM, 4 gm, plus ascorbic acid, 4 gm; and MM, 4 gm, plus ascorbic acid, 4 gm, plus cranberry cocktail, 1 liter--administered according to a cross-over design. Proteus vulgaris, Pseudomonas aeruginosa and E. coli were the most common urinary organisms. Proteus organisms were more often found in alkaline than in acidic urines, but the type of pathogen had no influence on urinary pH. Urinary formaldehyde concentration [HCHO] was lower in patients with Proteus infection (17.7 micrograms/ml) than in those with Pseudomonas (21.9 micrograms/ml) or E. coli infection (21.8 micrograms/ml). However, for Proteus infection, [HCHO] was higher in patients receiving MM plus ascorbic acid than in those receiving MM alone. Addition of cranberry cocktail to ascorbic acid did not enhance urinary pH, [HCHO] or methenamine efficacy. Our data suggest that in Foley catheter patients with chronic asymptomatic bacteriuria secondary to Proteus, Pseudomonas or E. coli infection, the type of urinary pathogen or the urinary pH cannot be used to predict the efficacy of methenamine therapy either with or without urinary acidifying agents.

Lack of effect of ascorbic acid, hippuric acid, and methenamine (urinary formaldehyde) on the copper-reduction glucose test in geriatric patients

Ascorbic acid and hippuric acid (from cranberry juice) are commonly used to acidify the urine for the purpose of enhancing the degradation of therapeutic methenamine mandelate to urinary formaldehyde. A study was made of 27 nondiabetic geriatric patients with indwelling Foley catheters and chronic bacteriuria who were treated with methenamine mandelate (4 gm), ascorbic acid (4 gm), and cranberry cocktail (1 liter) daily. All of 972 urine samples showed formaldehyde in mean concentrations between 14 and 25 microgram/ml. No glucose was found when the urine was tested by the copper-reduction method. In vitro false positive reactions reported in the literature do not appear to be duplicated as an in vivo problem.