Individual Reference Values Research Articles

The Impact of Fiber Supplementation on ADMA Levels

Asymmetric dimethylarginine (ADMA) is an emerging biomarker that has been associated with oxidative metabolism and increased cardiovascular risk. Little information is available regarding the effect of diet on ADMA. The authors studied 86 overweight/obese adults as part of a clinical trial of psyllium supplementation to determine whether 3 months of such supplementation would affect ADMA levels. Forty-one people in the intervention group received 14 g/day of psyllium in addition to their usual diet compared with 45 controls who followed their usual diet alone. The 2 groups were comparable at baseline in demographic characteristics and body mass index. Baseline ADMA levels were elevated in this overweight/obese population compared with published reference values in healthy individuals (0.75 vs 0.50 micromol/L). The change in ADMA levels over 3 months was not different in the psyllium group compared with the control group (-.03 vs -.01 micromol/L, P=.73). These findings do not support a significant effect of psyllium fiber supplementation on ADMA.

Drugs and ergogenic aids to improve sport performance

The use of biochemical aids to enhance athletic performance has a long history. In our current sporting culture we attempt to divide these between the accepted legal ‘ergogenic aids’ and the unacceptable performance-enhancing ‘drugs’. It is unclear whether this distinction would have been made 2000 years ago when Pliny the Elder reported the effects of Horsetail juice on performance. Interestingly, the sporting ergogenic effects of horsetail haven’t passed the test of time. In the middle ages its astringency, due to its high silica content, made it ideal for scouring pewter and wooden kitchen utensils. The juice's current ergogenic properties are more refined, its main use being in bath and shower products where a ‘natural conditioning effect’ is required. Perhaps more controversially, hidden amongst his 600 books, Claudius Galen, the 2nd century Greek physician to the gladiators, mentioned the positive effects of eating herbs, mushrooms and testicles. Galen believed that the right testicle was hotter and purer than the left, though whether this led to differential performance-enhancing effects was not rigorously tested. We shouldn't think that modern people are unusual in being obsessed with winning at all costs. Philostratos's (200 AD) view of the Ancient Greeks was that “They made war training for sport and sport training for war.” He was less impressed with his generation of sportsmen who “spent too much time eating, drinking and fornicating instead of actually training”. This was reflected in their poor choice of ergogenic aids. Although the ancient Spartan athletes trained on a meat-full diet of bulls, oxen, goats and deer, athletes of his generation ate white bread, poppy seeds, fish and pork [1]. They treated sports as “more of a hobby than a way of life”. Grumpy old men are clearly not a modern phenomenon! Clearly, if not actually preparing for war, … The use of biochemical aids to enhance athletic performance has a long history. In our current sporting culture we attempt to divide these between the accepted legal ‘ergogenic aids’ and the unacceptable performance-enhancing ‘drugs’. It is unclear whether this distinction would have been made 2000 years ago when Pliny the Elder reported the effects of Horsetail juice on performance. Interestingly, the sporting ergogenic effects of horsetail haven’t passed the test of time. In the middle ages its astringency, due to its high silica content, made it ideal for scouring pewter and wooden kitchen utensils. The juice's current ergogenic properties are more refined, its main use being in bath and shower products where a ‘natural conditioning effect’ is required. Perhaps more controversially, hidden amongst his 600 books, Claudius Galen, the 2nd century Greek physician to the gladiators, mentioned the positive effects of eating herbs, mushrooms and testicles. Galen believed that the right testicle was hotter and purer than the left, though whether this led to differential performance-enhancing effects was not rigorously tested. We shouldn't think that modern people are unusual in being obsessed with winning at all costs. Philostratos's (200 AD) view of the Ancient Greeks was that “They made war training for sport and sport training for war.” He was less impressed with his generation of sportsmen who “spent too much time eating, drinking and fornicating instead of actually training”. This was reflected in their poor choice of ergogenic aids. Although the ancient Spartan athletes trained on a meat-full diet of bulls, oxen, goats and deer, athletes of his generation ate white bread, poppy seeds, fish and pork [1]. They treated sports as “more of a hobby than a way of life”. Grumpy old men are clearly not a modern phenomenon! Clearly, if not actually preparing for war, …

An ELISA for apolipoprotein M reveals a strong correlation to total cholesterol in human plasma

Apolipoprotein M (apoM) is a 188 amino acid, 25 kDa protein belonging to the lipocalin protein superfamily. Although predominantly associated with high density lipoprotein, apoM is found in all major lipoprotein classes. To facilitate clinical studies of apoM, we have developed a sandwich ELISA for the measurement of apoM in human plasma. This method has been used to investigate normal apoM variation and to establish reference values for healthy individuals through the measurement of 598 samples from the Nordic Reference Interval Project Bio-bank and Database (NOBIDA) biobank. For women 18-49 years old, the reference interval for apoM was 0.58-1.18 micromol/l, whereas for women 50+ years and for men, the reference range was 0.61-1.30 micromol/l. Correlation studies of apoM with 26 common clinical chemical analytes from the NOBIDA database revealed a marked positive correlation with plasma total cholesterol (r = 0.52) and LDL and HDL cholesterol (r = 0.43 and 0.36, respectively). There was no statistically significant correlation with HDL/total cholesterol ratio or body mass index. In conclusion, a sandwich ELISA for the measurement of apoM in human plasma shows that apoM concentration is strongly correlated to total cholesterol in healthy individuals.

Allometric relationships between knee cartilage volume, thickness, surface area and body dimensions

To determine if anthropometric factors obtainable on routine examination can be used to estimate premorbid knee total subchondral bone area (tAB), cartilage surface area (AC), cartilage thickness (ThC), and cartilage volume (VC). Young individuals (21-39 years old) without history of knee joint pain, injury or disease were studied. Magnetic resonance imaging of the right knee was used to determine tAB, AC, ThC and VC for knee cartilage. Multilinear regression and curve fitting by variance minimization were used to model the data. VC and AC closely depended on tAB(1.5) in both men and women. This relationship subsumed all dependency on sex, height, weight and body mass index. In females, VC depended on height cubed and tAB on height squared. The relationship was much weaker in males. ThC was poorly related to tAB and VC. Confidence limits for VC standardized to tAB(1.5) were narrower than standardization to tAB or height. The absence of a tight relationship of VC and tAB with height in males suggests that the factors stimulating bone and cartilage growth may be different between sexes. The high correlation between tAB and VC across both sexes suggests, however, that (opposite to measures from routine clinical examination) tAB(1.5) can provide individual reference values for VC, against which changes with age and disease can be estimated with high confidence.

Eosinophil cationic protein in feces: Reference values in healthy and atopic individuals and patients with digestive diseases

Eosinophil cationic protein (ECP) is a good indicator of eosinophilic activity and turnover, serving as a marker of activity in allergic and gastrointestinal diseases characterized by predominantly eosinophilic tissue infiltration. Our aim was to compare ECP levels infeces from healthy individuals, atopic patients, and patients with digestive diseases and establish reference values for this clinical setting. Thirty-nine healthy adults, 28 atopic patients, and 14 patients with digestive diseases were enrolled. The atopic patients had been diagnosed with allergic rhinoconjunctivitis and/or asthma. ECP concentrations in the supernatants from processed feces adjusted for semidry weight (microg/g feces) were determined by fluorescent enzyme immunoassay. Between-group comparisons were performed of medians and interquartile ranges (IQR) by nonparametric tests. Median (IQR) ECP levels were 8.16 (4.11-17.61), 10.83 (5.18-18.49), and 13.02 (5.17-21.97) microg/g feces in controls, atopic patients, and digestive disease patients, respectively; mean (SD) levels were 14.53 (13.77), 13.93 (11.30), and 16.51 (14.79) microg/g of feces. No significant differences in the medians were observed between the atopic group and controls (p = 0.725), the atopic group and digestive disease patients (p = 0.513), or the controls versus the digestive disease patients (p = 0.694). We provide reference values for ECP levels in feces for normal and atopic adults. There is considerable variability in ECP levels in feces and the median levels are similar in healthy and atopic individuals and patients with digestive diseases.

Six-Minute Walk Test

Normative reference values are required if patient performance is to be put into perspective. This descriptive meta-analysis was undertaken to provide estimates of 6-minute walk test (6MWT) performance that could be used as normative reference values for individuals aged 60 years or older. Four bibliographic databases were searched online. Thirteen studies were identified that were usable. Meta-analysis demonstrated that reference values were best presented after grouping data by gender and age. Mean and 95% confidence intervals of 6MWT distances are presented separately for men and women in 3 age groups (60–69, 70–79. and 80–89 years). These consolidated values should provide a better estimate of normal performance than the individual studies from which they were derived.

Chromosomal aberration frequencies determined by conventional methods: Parallel increases over time in the region of a petrochemical industry and throughout the Czech Republic

The rationale for cytogenetic monitoring to determine if safe maximum allowable concentrations (MAC) of genotoxic chemicals are being maintained in a workplace is that exposure levels that do not increase chromosomal aberration frequencies are without harmful effects. Such monitoring, widely used in occupational health programs in the Czech Republic (CR), includes workers exposed to 1,3-butadiene (BD) or other chemicals. Studies of BD exposed workers in the years 1992, 1993, 1994, 1998, and 2004 compared mean frequencies of cells carrying chromosomal aberrations (frequency of aberrant cells=%AB.C.) in exposed workers with those in non-exposed matched controls in the same plant or in other individuals living in the region of the same petrochemical industry. Workers potentially exposed to acrylonitrile at this site were also evaluated in 2000, along with another unexposed matched control group. The %AB.C. values of exposed workers and their controls were also compared with reference values determined for normal individuals (ages 20-59 years) throughout the CR. Substantial discrepancies were noted between subjects in the region of the petrochemical industry (exposed workers and controls) for the years 2000 and 2004 and the reference CR-wide normal values that had been determined during an earlier time period. The matched non-exposed controls at the petrochemical industry site showed a mean %AB.C. value of 1.56+/-1.23% (N=25) in 1998; this rose to a mean of 2.65+/-2.29% (N=33) in 2000. In 2004, values for non-exposed matched controls at the industry site were 2.64+/-1.75% for males (N=25) and 2.38+/-1.74% (N=26) for females. However, the earlier determined CR-wide %AB.C. mean reference values for normal individuals were 1.77+/-1.16% (N=1305) for the interval 1977-1988 and 1.45+/-1.17% (N=2140) for the interval 1991-1999. As both reference values are substantially lower than those determined in 2000 and 2004 for the non-exposed matched controls at the petrochemical industry site, an analysis of the CR-wide mean normal individual reference values for this same 2000-2004 period was conducted. Unexpectedly, it was found that this reference value too had risen to 1.95+/-1.36% (N=1045) and was comparable to the concurrent matched control values at the petrochemical industry site where the monitoring studies were conducted. This substantial increase in %AB.C. values in 2000 and 2004, therefore, has occurred throughout the CR and is probably unrelated to chemicals uniquely present at the petrochemical industry site.

Nutritional determinants of plasma total homocysteine distribution in the Canary Islands

We sought to define plasma homocysteine reference values in healthy individuals in the Canary Islands and to determine its relations to folate and vitamin B12 intakes and concentrations. Cross-sectional study. Population-based representative sample of 557 participants, aged 18-65 years, from the Canary Islands Nutrition Survey (ENCA). All participants completed two 24-h dietary recalls and a general questionnaire collecting socio-demographic and health-related lifestyle information. Plasma homocysteine and serum vitamin B12 levels were measured by immunoassay, whereas folate levels through an automated ionic capturing method. Median plasma homocysteine was 11.9 micromol/l, higher in men (13.1 micromol/l) than in women (10.9 micromol/l) (P<0.001) and positively associated with age in both sexes (P<0.001). The prevalence of hyperhomocysteinaemia (> or = 15 micromol/l), 21.4%, was also greater in men (32.2%) than in women (13.4%). There were significant negative correlations between plasma homocysteine and serum (r=-0.32, P<0.001) and erythrocyte (r=-0.26, P<0.001) folate, as well as serum vitamin B12 (r=-0.28, P<0.001) concentrations. When divided in quartiles of vitamin intakes or concentrations, men with the lowest vitamin B12 and folate serum values had significantly higher plasma homocysteine concentrations than those in the other three quartiles. In women, hyperhomocysteinaemia was higher in the lowest quartiles of folate intake and serum and erythrocyte folate concentrations. These data provide further evidence that hyperhomocysteinaemia is a sensitive marker of inadequate folate and vitamin B12 status, allowing for the identification of those with greatest need for nutritional interventions.

When is an Individual an Individual Versus a Member of a Group? An Issue in the Application of the Dietary Reference Intakes

The Institute of Medicine (IOM) reports on Dietary Reference Intakes (DRIs) present a new paradigm for the description of nutrient requirements. Tradition and the DRI reports themselves have created an erroneous impression that the Recommended Dietary Allowance (RDA) is intended for use with individuals and the Estimated Average Requirement (EAR) is to be used with populations. Two recent IOM committee reports (one on nutrition labeling and one on Women, Infants and Children [WIC] food packages) challenge that interpretation, revealing the critical issues surrounding individuals versus groups or populations. The present paper examines the issues and concludes that the median requirement and Tolerable Upper Limit (UL) are the critical reference values for both individuals and populations. The RDA is both unneeded and lacking a sound scientific basis.

When is an Individual an Individual Versus a Member of a Group? An Issue in the Application of the Dietary Reference Intakes

The Institute of Medicine (IOM) reports on Dietary Reference Intakes (DRIs) present a new paradigm for the description of nutrient requirements. Tradition and the DRI reports themselves have created an erroneous impression that the Recommended Dietary Allowance (RDA) is intended for use with individuals and the Estimated Average Requirement (EAR) is to be used with populations. Two recent IOM committee reports (one on nutrition labeling and one on Women, Infants and Children [WIC] food packages) challenge that interpretation, revealing the critical issues surrounding individuals versus groups or populations. The present paper examines the issues and concludes that the median requirement and Tolerable Upper Limit (UL) are the critical reference values for both individuals and populations. The RDA is both unneeded and lacking a sound scientific basis.

Nível de desconforto para sensação de intensidade em indivíduos com audição normal

Loudness Discomfort Level (LDL), a test used in the hearing aid fitting process, has also been recommended to evaluate patients with tinnitus and/or suspect of hyperacusis. To determine LDL reference values for normal hearing individuals and to correlate the LDL to the Acoustic Reflex Threshold (ART). LDL was investigated in 64 normal hearing subjects, with ages between 18 and 25 years (53.1% female), in the frequency threshold of 0.5 to 8KHz and for speech (non-recorded, non-standardized connected discourse). Pulsate pure tones were presented for two seconds, with a one-second interval between each presentation. The initial stimulus intensity was at 50dB and was followed by ascending presentations, of 5dB each, until the subject referred initial discomfort with loudness. The testing procedure was performed separately in each ear, and was immediately repeated at the end of the test (test and retest situation). The choice of the ear that would start the testing procedure was alternated for each subject. After that contralateral acoustic reflexes ART were measured. The presence of the ART was indicated by a minimal needle deflection (larger than 0.05ml) on the emittance equipment. Median varied from 86 to 98dBHL, with no statistically significant differences between gender (p > 0.11), between ears (p > 0.36) and between the test-retest situation (p > 0.34). The determination coefficients (r2) of the linear regression model revealed absence of correlation between log(LDL) and log(ART). Normal hearing individuals have LDL between 86 and 98dBHL for all of the tested stimuli. Inter-subject differences and the good reproductivity suggest that the interpretation of the test should be cautious and analyzed considering the patient's history. The test can be an useful instrument go follow-up patients. No correlation was found between LDL and ART.

Determination of polybrominated diphenyl ethers in indoor dust standard reference materials

Polybrominated diphenyl ethers (PBDEs) have been measured for the first time in three different indoor dust Standard Reference Materials (SRMs) prepared by the National Institute of Standards and Technology (NIST). Two of these, SRM 2583 (Trace Elements in Indoor Dust) and SRM 2584 (Trace Elements in Indoor Dust), have been certified previously for lead and other inorganic constituents. A third, SRM 2585 (Organics in Indoor Dust), is a new indoor dust reference material prepared by NIST which will be certified for various organic compounds (polycyclic aromatic hydrocarbons, pesticides and polychlorinated biphenyls) in 2005 including certified concentrations for 16 individual PBDE congeners and reference values for an additional three PBDE congeners. Dust SRMs were analyzed for 30 PBDE congeners using high-resolution gas chromatography combined with low-resolution mass spectrometry operated in both negative chemical ionization (GC/ECNI-MS) and electron impact ionization (GC/EI-MS) modes. Sensitivity was an order of magnitude higher using GC/ECNI-MS relative to GC/EI-MS. These SRMs have been characterized and compared to the three PBDE commercial products (pentaBDE, octaBDE and decaBDE). PentaBDE and DecaBDE were present in all three SRMs and were the dominant commercial products, making up approximately 33% and 58%, respectively. Recent studies suggest that house dust may be a leading source of human exposure to PBDEs. These SRMs are the first reference materials with certified concentrations for PBDEs, which will aid in validating future measurements of PBDEs in house dust and other similar matrices.

New Approach for Evaluation of Quantitative Risk Factors of Venous Thromboembolism Using Individualized Reference Values.

The evaluation of quantitative risk factors of venous thromboembolism is characterized by several unsolved problems. The majority of quantitative components of hemostasis are dependent on age, sex, and hormone intake. The cut-off values determined in case-control studies depend on the specific patient/control group and can not be generalized on individuals with other characteristics. Furthermore, the approach does not give reference values dependent on age, sex, and hormone intake which are necessary for risk estimations in clinical practice.To overcome these disadvantages, we used a multiple regression analysis to create a system of reference values which change continuously depending on age, sex, and hormone intake according to the parameter distribution in healthy controls and calculated the relative risk of hemostatic components (729 patients with first VTE and 675 healthy controls). A significantly increased risk for venous thrombosis was associated with deficiency of protein S activity (odds ratio (OR) 2.8 to 6.1, p=0.0007), free protein S concentration (OR 2.7 to 20.4, p=0.0001), protein C activity (OR 3.2 to 9.4, p=0.0001), antithrombin activity (OR up to 75, p=0.0001), and increased levels of fibrinogen (OR 3.8, p=0.0001), factor VIII:C (OR 3.3, p=0.0001), factor IX (OR 2.3, p=0.0001), factor XI (OR 2.9, p=0.0001), vWF activity (OR 2.4, p=0.0001), and vWF antigen (OR 3.5, p=0.0001).In contrast to previously published studies, this new approach gives clinically important cut-off values dependent on age, sex, and hormone intake and allows to identify patients at increased risk for venous thrombosis on an individualized basis. Particularly parameters which are highly dependent on age and sex, like protein S activity, can be characterized more precisely using the described procedure. This comprehensive analysis demonstrates that, apart from well-known risk determinants, deficiency of protein S and increased values of FI, FVIII:C, FIX, FXI, vWF, and vWF-Ag are risk determinants predicting venous thrombosis.

Scalp hair analysis as a tool in assessing human exposure to heavy metals (S. Domingos mine, Portugal)

Hair samples from the scalp were used in a preliminary assessment of heavy metals exposure (As, Cd, Cr, Cu, Mn and Zn) of the human population living near an abandoned cupric pyrite mine (Mina de S. Domingos, Southeast Alentejo, Portugal). In parallel with the collection of hair samples, individuals from two different communities at the South and North of the mine area answered a questionnaire designed to obtain information about potential exposure pathways to these elements. The questionnaire allowed data collection about the most frequently consumed foodstuffs, drinking water sources, smoking habits, alcohol consumption and health condition. Higher concentrations, and subsequently higher ranges, of Cd, Cu and As were recorded in individuals living near the mine (MSD group), in opposition to individuals living several kilometers apart. Additionally, the concentrations recorded in the hair of some individuals from the MSD group were above the reference values for non-exposed individuals, suggesting their enhanced exposure. However, no significant differences were found for the average concentration of these elements between villages. Individuals from the CP and SC groups presented significantly higher concentrations of Zn and Mn in scalp hair. These results were in agreement with the concentrations of these elements recorded in soil samples. The water supplies of the area do not seem to be potential sources of trace elements for human beings. In opposition, individuals that frequently consume milk and cheese obtained from cattle that usually breeds in the area presented significantly higher concentrations of As and Mn in their scalp hair. Our results suggest that the population of S. Domingos mine area and neighbour localities may be exposed to some of the elements analysed namely Mn and Zn. The most likely exposure pathways seemed to be animal foodstuffs, however, a more detailed analysis of these products, as well as garden vegetables and fruits, should be performed.

Comparative study of equations of estimate of the maximum heart rate

Recently, researches have developed a new equation to estimate maximum heart rate (HRmax) for individuals from both male and female sexes and they also have demonstrated that equation (220-age), usually utilized, tends to overestimate HRmax. The objective of this work was to evaluate the precision and applicability of HRmax equation among male and female sexes, both of them healthy, 17 up to 33 years-old. In order to determine the reference of HRmax, called as HRref, it was taken in turn maximum effort test utilizing electrical treadmill machine with incremental progressive weights. Results showed that studied equations (220 - age) (198.40±3.70), Jones et al. (196.00±2.30) and Tanaka et al. (192.90±2.50), have low correlation with observed HRref and variation of (0.07; 0.02; and 0.02), respectively, showing no signifi cance (p > 0.05). It was also verifi ed that excluding those equa- tions proposed by Tanaka et al. all the others showed tendency to overestimate Wilk's E HRref = 0.001 F (3.119) = 29265.85; p = 0.01. It is concluded that among analysed equations, those of Tanaka et al. have best relationship with young individual's reference values. It is suggested more studies with older individuals.

Inherent biological variation and reference values.

There is a need for revisiting theoretical concepts and practical applications of conventional population-based reference values to make for better clinical use of laboratory data. Knowledge of the underlying biological variation of quantities examined in medical laboratories is vital to understanding the proper generation and application of traditional population-based reference values. Appreciation of the biological changes that occur over the span of life is a necessary prerequisite to deciding whether stratification of reference values according to age is likely to be necessary. Knowledge of the detail of predictable biological cyclical rhythms is required for correct clinical interpretation of laboratory data and appropriate collection of specimens at times relevant to the clinical purpose. Quantitative data on inherent within- and between-subject biological components of variation have shown the marked individuality of most quantities of interest in laboratory medicine. This individuality casts light on why examinations are not generally very successfully applied in population screening or case-finding. Consideration of individuality demonstrates why stratification of reference values is often very advantageous. Individuality provides an indisputable argument for better use of individual specific reference values.

Postictal serum levels of antiepileptic drugs for detection of noncompliance

Medication noncompliance (NC) is thought to be a major cause of insufficient seizure control. In an explorative study we investigated whether postictal serum levels (PISLs) of antiepileptic drugs (AEDs) are a reliable indicator of NC. Young adults with epilepsy on a stable AED regimen were asked to contact medical service as soon as possible when a seizure occurred to obtain serum levels of their AEDs. PISLs were compared with the mean value of two routine serum levels of the same medication. PISLs lower than 50% of the individual reference value were regarded as an indicator of NC. PISL samples in 61 seizures of 52 patients treated mainly with carbamazepine, valproic acid, or lamotrigine were evaluated. A drop in serum levels >50% indicating NC was noted in 44.3% of the seizures. Determination of PISLs seems to be a simple and useful method for detecting or ruling out irregular intake patterns as a cause of “breakthrough” seizures.

Transport stress in horses: an electromyographic study on balance preservation

In order to validate the hypothesis that horse transport stress might also be the result of efforts spent in balance preservation, heart rate (HR) and muscular activity (MA) were analysed in eight Warmblood horses, with respect to individual rest reference values. Electromyographic (EMG) data were collected from Splenius muscles (left and right side), as representative of body anti-gravitational activities. The EMG data performed during each balancing effort were firstly quantified and then reported as percentage of the activity in respect to basal EMG signals obtained during resting; before loading the animal. These data were correlated with the HR recorded at the same time. Moreover, a videotape, synchronised with the EMG and HR data, was made to better recognise and to distinguish the muscular activities necessary for the preservation of balance, from the other muscular activities performed (e.g. searching, scratching, etc.). Although horses displayed HR and EMG individual quantitative differences (in power and number of events), the regression analysis showed that these two electrophysiologic parameters were strictly correlated in all animals. It was concluded that: (a) EMG and HR data can be used to evaluate efforts to preserve the animal’s balance and that (b) this kind of effort might be considered one of the main transport stress factors. Consequently, we deduced that the efforts spent by the animals for a continuous postural adjustment can be considered as a physical expression of both muscular and emotional stress related to road conditions (traffic and/or physical road conditions) and the driver’s specific driving ability.

Determination of Zn/Cu ratio and oligoelements in serum samples by total reflection X-ray fluorescence spectrometry for cancer diagnosis

The method of quantification using the Compton peak as an internal standard, developed in a previous work, was applied to the routine determination of Fe, Cu, Zn and Se in serum samples from normal individuals and cancer patients by total reflection X-ray fluorescence spectrometry. Samples were classified according to age and sex of the donor, in order to determine reference values for normal individuals. Results indicate that the Zn/Cu ratio and the Cu concentration could prove to be useful tools for cancer diagnosis. Significant differences in these parameters between the normal and cancer group were found for all age ranges. The multielemental character of the technique, coupled with the small amounts of sample required and the short analysis time make it a valuable tool in clinical analysis.

Monitoring of fluorine in urine samples of patients involved in the Tokyo sarin disaster, in connection with the detection of other decomposition products of sarin and the by-products generated during sarin synthesis

We developed a new assay method for fluoride anion (F −) a specific metabolite of sarin. Trimethyifluorosilane (TMFS) was derivatized from F − with trimethylsilanol, and TMFS was detected with a GC–flame ionization detector (FID) and capillary column system. The linear range, detection limit and recovery rate were 0.02–10 ppm, 0.01 ppm and 97.3–103.0%, respectively. The patients were reported to be exposed only once to the toxic substance (a bolus exposure). F − excretion in urine of the hospitalized patients demonstrated three or four peaks. Other common metabolites of sarin and by-products such as methylphosphonic acid (MPA) and isopropyl alcohol (IPA) also showed two or three peaks. These results suggested that the patients were exposed to not only sarin but also fluoride and isopropyl alcohol containing by-products. The sum of MPA excreted was 0.3–90 mM, far exceeding the human lethal dose of sarin. The residual acetyicholine esterase activity of erythrocytes on admission (4.7–57.2% of the individual reference value) of the patients showed statistically significant relationships only with the initial values of F − and the isopropyl methylphosphonate. This evidence also suggested the exposure to fluoride and isopropyl alcohol-containing by-products.