Hypertension, and blood pressure response to graded exercise in young obese and non-athlethic Nigerian university students.

Hypertension, and the effect of graded exercise on Blood pressure (BP), in 60 obese non-athletic young medical students (40 females and 20 males) with Body Mass Index (BMI) greater than 30 were studied. The subjects were in the age range of 18-22 years with mean age of 20.30 +/-1.32 years. Twenty percent of the males and 7 percent of the females were found to be hypertensives [P < 0.05] and the severity of the hypertension significantly [P < 0.05] increased linearly with increase in BMI (r =0.6). Our study reveals a positive direct correlation between obesity and socioeconomic status and BP. Marked increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), time of return (RT) were observed in the obese individuals compared to control at all levels of graded exercise with the highest rises seen during severe exercise. Among the obese subjects, the increases in BP were more in the males than females, but time of return was higher in females than males. This study further confirms that obese young individuals are prone to early onset of hypertension and thus other cardiovascular diseases and less tolerant to physical exercises. Our results add to the evidence that hypertension is common among obese young adults.     

Relationships between blood pressure, polymorphism of angiotensin-converting enzyme (ACE), body composition and biochemical characteristics in elderly Slovaks

Epidemiological studies have demonstrated that several specific environmental factors and candidate genes influence the human variation in blood pressure. The aim of this study was to investigate variables associated with blood pressure; with a particular emphasis on the differences in insertion/deletion (I/D) polymorphism of the human angiotensin-converting enzyme (ACE), the body composition and the recognized risk factors for atherosclerosis among elderly males and females. A total of 374 participants (174 males and 200 females) aged from 60 to 90 years were recruited from different parts of Slovakia. The elderly were not bed-ridden, nor mentally impaired, they were able to manage their daily activities by themselves. The ACE I/D polymorphism was determined by PCR amplification of the ACE gene sequence. Body composition variables were obtained by bioelectrical impedance analysis, using the BIA 101 soft tissue-body impedance analyzer (Akern, S.r.l.). The subjects were determined to be hypertensive (blood pressure > or = 140/90 mm Hg) or normotensive (blood pressure < or = 140/90 mm Hg ). These two subgroups of males and females did not differ significantly in their mean ages. As expected, the hypertensive subjects of both sexes showed significantly higher mean values in systolic (SBP) and diastolic blood pressure (DBP), in body mass index (BMI), and in the mean values of their plasma glucose and extracellular water (ECW). The genotype distribution and allele frequencies in the whole sample (D = 0.5474, I = 0.4526) fell within the Hardy-Weinberg equilibrium. The frequency of the deleterious D allele in the normotensive (0.5532) and hypertensive (0.5516) subjects was not significantly different. The ACE I/D genotypes did not associate either with the systolic (p = 0.836) or diastolic BP (p = 0.629). From the other variables that may induce differences in blood pressure, a statistical effect was detected for glucose, Na/K, and Apo A1/ApoB ratios and physical activity on SBP, and for ApoA1, physical activity, BMI and total cholesterol on DBP.     

The relationship between 24-hour ambulatory blood pressures and laboratory measures of cardiovascular reactivity

The relationship between 24-hour ambulatory blood pressures (ABP) and blood pressures (BP) obtained during laboratory stressors was examined. Thirty normotensives (equal males and females) underwent ABP monitoring on three occasions separated by a week. They also underwent a laboratory assessment which included standard stressors (i.e., mental arithmetic, cold pressor, orthostatic response, treadmill exercise). Correlational analyses found laboratory pressures to be significantly correlated with ambulatory pressures, with laboratory baseline BPs showing higher correlations to the ambulatory BPs than the BPs obtained during laboratory stressors. In addition, gender effects were examined. In the correlational analyses between ABPs and laboratory BPs, males and females did not differ significantly in the strength of the correlations. In terms of absolute values, males were found to have significantly higher SBP during ambulatory monitoring, random-zero recordings, calibration readings, and during baselines of the laboratory assessment. There were no gender effects for these measures with respect to diastolic blood pressure or heart rate. There were also no gender effects on reactivity to laboratory stressors as measured by change scores. Exploratory analyses found no significant effect of history of familial hypertension on either the ABPs or the laboratory pressures.     

Age-sex and diurnal variation of blood pressure in different nutritional states among the adult Telegas of Kharagpur in West Bengal, India

An anthropological investigation among the endogamous Telega population (106 adult individuals including 51 males and 55 females) in the district of Paschim Medinipur of West Bengal, India shows wide range of age-sex as well as diurnal variation of mean blood pressure (MBP) with reference to different nutritional status. Distribution of MBP shows distinct bias for sexes separately on different occasions and in association with age and other physiological conditions like menopause in females. Records of increase of blood pressure from morning to evening also indicate clear diurnal change in both male as well as in the female samples with some variations when compared between the two sexes. Results also help us to understand and to record the variation of blood pressure as a physiometric trait in the population under study. Data indicate that nearly 30% of males and more than 30% of females are living at the level of undernutrition. Nutritional status is measured by anthropometric measurements, e.g. height, weight, mid arm circumference (MUAC) and further calculation of body mass index (BMI). Distribution of MBP at different BMI and MUAC levels and Pearson correlation and regression analysis--all suggest that age, BMI and MUAC have significant impacts on BMI with some sex-related variations.     

Plasma Cortisol Levels Increase with Age in Obese Subjects

In order to assess the influence of age, sex, and body mass on plasma cortisol concentrations, we measured the 24-hour Integrated Concentration (IC) of cortisol (F) in 36 obese subjects (16 males, 20 females) aged 5.3–56.4 years, BMI=35.5 ± 7.3 kg/m² and compared with 119 nonobese subjects, body mass indices (BMI) 21.2 ± 2.7 kg/m², aged 8.8–66.2 years (55 males, 64 females). Subjects were nondiabetic, normotensive, without history of psychiatric illness, and otherwise in good health. IC studies were performed using a continuous blood withdrawal methodology, and IC-F was assayed from the 24 hour pooled sample by a protein binding method. The effect of age and gender on IC-F was analyzed by multivariate regression. In the nonobese group there was no effect of age or sex on IC-cortisol levels, the mean IC-F= 173.8 ± 44.1 nmol/L. A statistically significant but weak negative effect of BMI on IC-cortisol (r = -.18, p<0.05) was present. In the obese subjects there was a significant increase in IC-cortisol levels with age IC-F(nmol/L)=2.76 x age(years) + 85.0 (r²=.36, p<0.0001). IC-cortisol levels tended to be lower in obese males than females when controlled for age (p<0.05). We conclude that in nonobese subjects IC-F levels are independent of age and gender. However, there is a significant increase of IC-cortisol levels with age in obese individuals. The observed increase of IC-cortisol with age may contribute to metabolic complications of obesity.     

ACE gene and physical activity, blood pressure, and hypertension: a population study in Finland.

The study evaluated the association of the insertion/deletion polymorphism of the angiotensin-converting enzyme gene (ACE I/D) with self-reported moderate-intensity leisure time physical activity (MILTPA), arterial blood pressure (BP) and history of hypertension (HT). A representative population-based sample of 721 middle-aged adults (358 women) from two areas of Finland was genotyped for the ACE I/D. After exclusion criteria were applied, 455 subjects (288 women) were selected for the analysis. The distribution of the ACE I/D genotypes did not differ significantly among frequent vs. nonfrequent MILTPA groups (chi(2) = 2.556; df = 2; P value = 0.279). The main predictors of BP were male gender, age, body mass index, and arterial pulse. Additionally, tobacco smoking and alcohol consumption also had a significant main effect on diastolic BP. HT was significantly more frequent in subjects with obesity, family history of cardiovascular disease, or lower educational level. As for BP, neither ACE I/D nor MILTPA was associated with HT. The study confirmed recent reports from population-based studies of no association between ACE I/D and physical fitness. The study also confirmed a lack of association between ACE I/D and BP or HT.     

Body height and blood pressure regulation in humans during anti-orthostatic tilting

The hypothesis was tested that the cardiovascular changes during an upper body anti-orthostatic maneuver in humans are more pronounced in tall than in short individuals, because of the larger intravascular hydrostatic pressure gradients. In 34 males and 41 females [20-30 yr, body height (BH) = 147-206 cm], inter-individual multiple linear regression analyses adjusted for gender and body weight were conducted between changes in cardiovascular variables versus BH during tilting of the upper body from vertical to horizontal while keeping the legs horizontal. In all the subjects, tilting induced increases in stroke volume and arterial pulse pressure and a decrease in heart rate, which each correlated significantly with BH. In males (n = 51, BH = 163-206 cm), 24-h ambulatory mean arterial pressure increased significantly with BH (P = 0.004, r = 0.40, α = 0.15 mmHg/cm) so that systolic/diastolic blood pressure increased by 2/2 mmHg per 15 cm increase in BH. There was no significant correlation between mean arterial pressure and BH in females (n = 53, BH = 147-193 cm). In conclusion, a larger BH induces larger cardiovascular changes during anti-orthostatic tilting, and in males 24-h ambulatory mean arterial pressure increases with BH. The lack of a mean arterial pressure to BH correlation in females is probably because of their lower BH and greater variability in blood pressure.     

Hypertension Increases With Aging and Obesity in Chimpanzees (Pan troglodytes)

Cardiovascular disease is a primary cause of morbidity and mortality in captive chimpanzees. Four years of blood pressure (BP) data were analyzed from a captive former laboratory population of 201 healthy adult chimpanzees with assessment of age and obesity on elevated BP. Five different measures of obesity were compared: abdominal girth, basal metabolic rate, body‐mass index (BMI), body weight, and surface area. Systolic BP varied by sex. Obesity did not influence male BP. For females, obesity was a significant determinant of BP. The best measure of female obesity was basal metabolic rate and the worst was BMI. Median systolic BP of healthy weight females (<54.5 kg) was significantly lower (128 mmHg) than overweight or obese females (140 mmHg), but both were lower than all males (147 mmHg). For diastolic BP, neither sex nor any of the five obesity measures was significant. But age was highly significant, with geriatric chimpanzees (>30 years) having higher median diastolic BP (74 mmHg) than young adults of 10–29 years of age (65 mmHg). By these criteria, 80% of this population is normotensive, 7% prehypertensive, and 13% hypertensive. In summary, systolic BP intervals required adjustment for obesity among females but not males. Diastolic BP required adjustment for advanced age (≥30 years). Use of these reference intervals can facilitate timely clinical care of captive chimpanzees. Zoo Biol. 32:79‐87, 2013. © 2012 Wiley Periodicals, Inc.     

Racial and gender effects on the relaxation response: Implications for the development of hypertension

This study was designed to explore the effect of race and gender on the forehead muscle tension and finger temperature response to biofeedback-assisted relaxation training in individuals with normal blood pressure. Forty-five subjects—18 Black and 27 White, 25 males and 20 females—participated in eight sessions of autogenic relaxation training and thermal biofeedback. Multivariate analysis of variance of the variables measured at baseline (systolic BP, diastolic BP, sodium excretion, anxiety) was significant for gender. Univariate analysis showed males different from females in DBP, Na⁺ excretion, and trait anxiety. Pretest values of muscle tension were similar by gender, but pretest temperatures were lower in males than females. Repeated measures ANOVA for muscle tension showed a significant effect of period. For temperature, a significant effect of period, gender, and gender × period was observed. Males increased temperature more than females. There was no effect of history of hypertension on the relaxation response. Multiple regression performed on change in muscle tension and change in temperature showed that pretest muscle tension predicted change in muscle tension. Four variables contributed to the variance in change in temperature: pretest temperature, sodium excretion, and state and trait anxiety.     

Association of Central Obesity With the Severity and Audiometric Configurations of Age‐related Hearing Impairment

To investigate the effect of central obesity on the severity and characteristics of age‐related hearing impairment (ARHI), we recruited 690 adult subjects with normal or symmetrical sensorineural hearing loss (SNHL). The effects of age, gender, morphometry, habits, systemic diseases, and environmental noise exposure on average pure tone hearing level at low frequencies (pure tone audiometry (PTA)‐low) and high frequencies (PTA‐high) were analyzed. After adjusting for age, gender, systemic disease, and other variables, waist circumference (WC) showed a significant positive association with PTA‐low and PTA‐high. In females, PTA‐low and PTA‐high only showed significant positive association with age, but not with WC or other variables. However, PTA‐high showed a positive association with borderline significance with WC in female subjects older than 55. In males, WC as well as age and noise exposure showed significant positive associations with both PTA‐low and PTA‐high, primarily in subjects younger than 55. When both WC and BMI were taken into account in a backward stepwise multivariate linear regression analysis, WC, but not BMI, showed a significant positive association with PTA‐low and PTA‐high in males younger than 55, and with PTA‐high with borderline significance in females older than 55. However, the audiogram patterns were not significantly affected by central obesity in either age or gender. Our results suggest that WC was, even after adjustment for BMI, an independent risk factor of ARHI, particularly for low and high frequencies in males younger than 55 and for high frequencies in female subjects older than 55.     

Hair Toxic Element Content in Adult Men and Women in Relation to Body Mass Index

The primary objective of the current study was to estimate the hair toxic metal content in adults in relation to body mass index. A total of 1,229 persons including 719 women and 510 men were examined. All subjects were divided into two age groups: 1 and 2 periods of adulthood. All men and women were also subdivided into groups in relation to their values of body mass index (BMI): underweight, normal weight, overweight and obese. Hair aluminium (Al), beryllium (Be), cadmium (Cd), mercury (Hg), lead (Pb) and tin (Sn) content was evaluated using mass spectrometry with inductively coupled plasma. It has been shown that increase in body weight is accompanied by elevated hair cadmium content in women. At the same time, no significant alteration of hair cadmium concentration was observed in males. Higher values of scalp hair mercury and lead content were observed in men and women with increased body mass index independently of their age. BMI-related elevation of hair tin content was registered only in men of the first period of adulthood. A significant correlation between hair metal content and the values of BMI was observed for mercury independently of the gender of the subjects, whereas BMI values correlated significantly with hair cadmium levels in women and lead and tin levels in men. It has been also estimated that hair cadmium, mercury and lead levels in men exceed the respective values in women.     

Hematologic and blood biochemical variables of captive chimpanzees: cross-sectional and longitudinal analyses

Hematologic and blood biochemical variables are of great importance in medical and veterinary practice. In addition, these analytes may have significance as potential biomarkers of aging. Previous reports on normative values of these variables in the chimpanzees are based on cross-sectional studies that did not include individuals of advanced age. To address this omission, we performed cross-sectional and longitudinal analyses of hematologic and blood biochemical data collected from chimpanzees over a 9-year period. One-hundred forty-six females and 106 males of ages representing the entire life span of the species were studied. We derived normative cross-sectional values of 14 commonly measured hematologic and 20 blood biochemical variables, which should provide a useful reference for clinical blood studies in chimpanzees. In addition, we found in a cross-sectional regression analysis of our data that most analytes varied significantly between males and females, and that they varied markedly with age. Most variables had year-to-year consistency within the same individuals, as indicated by statistically significant intra-year correlation coefficients. Finally, we performed a longitudinal analysis of the analytes in chimpanzees by calculating the slopes and intercepts of the best-fitting trend line for each individual. The resulting slopes were analyzed by sex and by decade of age of subjects to determine whether trends were consistent. Consistent trends detected in the longitudinal analysis were usually restricted to the first decade of life, and thus represented maturational processes. The overall lack of within-animal trends covering all or most of the period from early adulthood through old age in this 9-year study suggests that a longer period of follow-up than used here may be required to document senescence-related changes.     

Plasma BDNF levels vary in relation to body weight in females

Brain derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of depression as well as neuropsychiatric and neurodegenerative disorders. Recent studies show a role of BDNF in energy metabolism and body weight regulation. We examined BDNF levels in plasma and cerebrospinal fluid (CSF) samples from age matched elderly depressed and control subjects. Also, the association of BDNF levels with age, gender, body weight, body mass index (BMI), and cognitive performance was evaluated. We did not find any significant differences in plasma and CSF BDNF levels between depressed and control subjects. Plasma BDNF levels were negatively correlated with age (but not with BMI and body weight), when analyses were performed including both depressed and control subjects. A significant reduction in plasma BDNF levels was observed in females as compared to male subjects, and the change in BDNF levels were significantly and positively related to body weight in females. Furthermore, significant increases in Total Recall and Delayed Recall values were found in females as compared to males. In conclusion, the lower BDNF levels observed in females suggest that changes in peripheral BDNF levels are likely secondary to an altered energy balance. However, further studies using larger sample size are warranted.     

Prevalence of dyslipidemia and mean blood lipid values in Taiwan: results from the Nutrition and Health Survey in Taiwan (NAHSIT, 1993-1996)

This paper reports the blood lipid status of people aged 4 years and older in Taiwan. The data is based on the Nutrition and Health Survey in Taiwan (NAHSIT: 1993-1996), which adopted a multi-stage, stratified clustering sampling scheme. Altogether, 5097 subjects (2451 males and 2646 females) had data on triglyceride and 5643 subjects (2736 males and 2907 females) had data on cholesterol. We found that (a) cholesterol levels of males were lower than females in mid-to old age group (> or = 45 years old); (b) triglyceride values of females were lower than males in young adulthood (19-44 years), but higher than males after the age of 45 years, and (c) adult females had higher HDL-C value and lower ratio of total cholesterol to HDL-C than males. The prevalence of hypercholesterolemia was 10.2% in adult males and 12.6% in mid-to-old aged men, and that in females was 11.2% and 24.4%, respectively. The prevalence of hypertriglyceridemia was 13.4% and 6.1% in adult males and females (> or = 19 years as a whole), respectively. It was 12.3% in mid-to-old aged men (> or = 45 years), and 11.9% in women. The mean cholesterol values were similar to values of several previous surveys in different areas of Taiwan. But it was higher than those in some areas of Mainland China, and lower than those of western countries. People in metropolitan cities had a higher level of blood cholesterol than other areas. The average triglyceride values of males and females were higher than those of previous studies in Taiwan and of people in Mainland China. Mountainous stratum with predominantly aboriginal residents had higher level of triglycerides and body mass index (BMI) than other strata. The associations between dietary intakes of men and women and blood lipids were examined controlling for age and BMI. Result showed that Keys score, which was derived from saturated fat, polyunsaturated fat and dietary cholesterol of a 24-hour recall, was positively related to blood cholesterol and LDL-C in men, but not in women. Average alcohol intakes per day were related to HDL-C positively, but LDL-C negatively in men and women. The regional differences in blood lipid profiles in Taiwan are consistent with the dietary and life-style variations island-wide.     

Changes in metalloproteinases in healthy normotensive patients with high-normal blood pressure

INTRODUCTION: High-normal blood pressure (HNBP) seems to be related to increased cardiovascular risk in healthy, normotensive subjects, while essential hypertension is associated with an increase in extracellular matrix content, especially fibrillar collagen type I. The aim of our study was to investigate whether collagen degradation is altered in healthy normotensives with HNBP, and whether this alteration could be related to disturbances in the matrix metalloproteinases plasma concentration, and to compare the findings to those of healthy normotensives with normal blood pressure (NBP) levels, matched for age, sex and BMI. METHODS: Twenty six (14 males, 12 females) healthy, normotensive patients with HNBP, mean age 52 +/- 5 yrs, and BMI 23 +/- 1.5 kg/m(2) (group A), and 24, healthy normotensive patients (13 males, 11 females) with NBP, mean age 53 +/- 6 yrs, and BMI 23.2 +/- 1.4 kg/m(2) (group B), were studied. The two groups were matched for age, sex and BMI. Plasma levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitors (TIMP-1) and (TIMP-4) were determined by relevant ELISA in the study population. RESULTS: Plasma MMP-9 levels were significantly higher, while TIMP-1 and TIMP-4 levels were significantly lower in group A compared to group B, (MMP-9 579 +/- 147 versus 294 +/- 111 ng/mL, TIMP-1 178 +/- 45 versus 237 +/- 35 ng/mL p < 0.01, and TIMP-4 2.2 +/- 1.4 versus 4.4 +/- 2.1 p < 0.04 respectively). CONCLUSIONS: Our findings suggest that healthy normotensives with high-normal blood pressure have significantly increased MMP-9 and decreased TIMP-1 and TIMP-4 plasma levels compared to healthy normotensives with normal blood pressure. These findings need further investigation.     

Non-dipping blood pressure in the metabolic syndrome among Arabs of the Oman family study

Objective: The objective was to examine the circadian changes in blood pressure and their relation to the metabolic syndrome and its components in Omani Arabs. Research Methods and Procedures: Ambulatory blood pressure (ABPM) was recorded in 1124 subjects from 5 large, extended, consanguineous, and young Arab pedigrees. According to the International Diabetes Federation's definition, 264 subjects had the metabolic syndrome, a prevalence of 23%. Subjects were defined as non‐dippers when their nocturnal systolic blood pressure (SBP) fell by <10% from daytime SBP. Results: Non‐dippers with the metabolic syndrome were 131 of 264 (50%), compared with 265 of 860 (31%) without the metabolic syndrome. Of the non‐dippers, 99 of 131 (76%) were females and 32 of 131 (24%) were males. Daytime and nighttime SBP and DBP and nighttime pulse pressure were significantly higher in non‐dipper subjects with the metabolic syndrome. The important determinants of a non‐dipping BP in this cohort were high BMI and high serum triglycerides. Discussion: We hypothesize that obesity and nocturnal volume‐dependent hypertension may be involved in the pathophysiology of non‐dipping in the metabolic syndrome. This study showed that non‐dipping BP was common in subjects with the metabolic syndrome. Higher 24‐hour blood pressure load may add to the indices of the overall cardiovascular burden already associated with the metabolic syndrome.     

Gender dependency of circadian blood pressure and heart rate profiles in spontaneously hypertensive rats: effects of beta-blockers

This study investigated (i) blood pressure (BP), heart rate (HR), and their relation to urinary NOx and eNOS protein expression in male and female spontaneously hypertensive rats (SHR), as well as (ii) gender-dependent cardiovascular effects of nebivolol (NEB) in comparison to metoprolol (MET) in SHR. BP and HR were measured telemetrically after a single intraperitoneal application of NEB or MET at 07.00 and 19.00 h in male rats and at 19.00 h in proestrus female rats. The two β-blockers varied in time of decreasing BP and HR and also in duration. In males, MET decreased BP and HR for few hours exclusively when applied at the onset of the activity phase (i.e., at 19.00 h), while after its application at 07.00 h, BP and HR were unchanged. In females, MET also caused a short-lasting BP and HR reduction, with the effect being more pronounced than in males. In males, NEB at either dosing time decreased HR and BP to a greater extent than did MET. This effect was evident both during the activity and rest periods and persisted for at least five days. In females, NEB provoked a similar, but more pronounced, effect on BP and HR in comparison to males. These findings demonstrate that significant gender-dependent differences in the circadian profile of BP and HR exist. BP and urinary NOx as well as eNOS expression are inversely correlated, and the cardiovascular effects of NEB and MET vary, depending on the time of application as well as gender.     

Serum lipids, body mass index and waist circumference during pubertal development in Spanish adolescents: the AVENA Study.

AIM: To describe the effects of chronological age and biological age (pubertal development) on serum lipid and lipoprotein levels, body mass index (BMI) and waist circumference in Spanish adolescents. METHODS: A representative Spanish sample of 526 adolescents (254 males and 272 females), were studied. Total cholesterol (TC), high density lipoprotein cholesterol (HDLc), triglycerides, apolipoprotein A1 and B, and lipoprotein(a) were measured, and low density lipoprotein cholesterol (LDLc) was calculated. Additional measurements included BMI and waist circumference. Adolescents were classified according to chronological age, and pubertal development (also age of menarche in females). RESULTS: In males, serum TC levels were lower at late puberty in comparison with early puberty, and serum LDLc levels were lower at late puberty in comparison with mid and early puberty. Serum HDLc levels were lower at mid puberty in comparison with early and late puberty. Serum TC and LDLc levels were not different when analyzed according to chronological age. In females, HDLc levels were lower at late puberty in comparison with early and mid puberty, but no differences were found when HDLc and the other studied lipid and lipoprotein variables were analyzed according to chronological age, or age of menarche. All the observed differences persisted after adjusting for BMI and waist circumference. In female adolescents, both BMI and waist circumference were higher at late puberty in comparison with early and mid puberty, while in males, BMI and waist circumference were different when analyzed according to chronological age. CONCLUSION: The results suggest that the assessment of pubertal development may provide additional valuable information when interpreting lipid profile and body fat in adolescents.     

Automatic method for quantitation of mercury in blood, plasma and urine.

Here we report our experience of quantification of mercury in blood, plasma and urine by using modifications of a procedure for cold vapour atomic absorption. We have tried: (1) modifications of the instrumentation including the tower, the cell and apparatus for measurement; (2) to increase the volume of sample, avoiding problems caused by foaming and background to arrive at a reliable method with low detection limit. Blood and plasma samples were digested overnight in a mixture of nitric acid and perchloric acid (1:5). Recovery of known additions of mercury was close to 100%. Coefficients of variation (CV) within runs and between runs was for B-Hg 4.7 and 9.5, respectively at 20 nmol/l, and for U-Hg 1.8 and 5.2, respectively at 57 nmol/l. The same detection limit of 5 nmol/l was obtained with blood, plasma and urine. This is in the lower range of non-occupationally exposed normal subjects. The results, including those obtained in sample exchange with other laboratories and with reference materials, indicate that the accuracy of this method for quantification of mercury is good.