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Alpha-tocopherol level was measured spectrofluorometrically in 279 healthy volunteers to establish reliable reference values and to compare possible sex and age-related differences. In the present study, men had higher tocopherol levels than women (p<0.05) and older subjects had lower values. This study provides reference values for alpha-tocopherol that may assist it evaluating the anti-oxidant defense.
The automated (AutoAnalyzer II) determination of cholesterol in nine serum pools in the concentration range 3.465-8.871 mmol/l, gave results that were approximately 10% higher than reference values when the analyses were based on unesterified cholesterol standards containing the same amount of water as the sample extracts (1963 analyses in 12 laboratories during a 12 month period; automated value = 0.032 + 1.10 X (Reference value)). A serum calibration procedure was successful ilues, and was equally effective in correcting the values observed for aliquots of 368 fresh-frozen plasma samples analyzed in each of the 12 laboratories during a 38 month period.
The effect of positive tissue pressure on blood flow in subcutaneous adipose tissue and skeletal muscle tissue was studied in eight healthy humans resting in the supine position. Blood flow was measured by the local 133Xe clearance technique in the mid-calf region. Tissue pressure was increased by inflating a whole leg cuff to pressure levels between 10 and 60 mmHg. In subcutaneous tissue as well as in skeletal muscle tissue, blood flow and local vascular resistance was not significantly changed at compression with 10 mmHg (P greater than 0.1). The pressure-flow curve obtained from subcutaneous tissue was curvilinear with the convexity towards the pressure axis, as blood flow was significantly reduced, while local vascular resistance was significantly increased by further increase in cuff pressure. Compression with 60 mmHg reduced subcutaneous blood flow to 21% of the reference value (P less than 0.01), while local vascular resistance was increased 91% above the reference value (P less than 0.01). In skeletal muscle tissue the pressure-flow curve was curvilinear with the convexity towards the flow axis, as local vascular resistance was reduced to 93% of the reference value at compression with 20 mmHg (P less than 0.05). Compression with 60 mmHg reduced muscle blood flow to 41% of the reference value (P less than 0.01), while local vascular resistance was increased 32% above the reference value (P less than 0.05). Venous distension in compressed subcutaneous tissue increased blood flow with 46% (P less than 0.02), while regional vascular resistance was reduced with 53% (P less than 0.01). In skeletal muscle tissue the same procedure was not followed by significant changes in blood flow or vascular resistance (P less than 0.01). It is concluded that the observed difference between the two tissues could be caused by a difference in vessel collapsibility. Another mechanism responsible could be a difference in autoregulatory capacity.
AIM: We undertook the present study to establish reference data for serum thyroid function tests in a previously iodine-deficient area. METHODS: Data from 4298 individuals, 20-79 years of age were available for the present analysis. Thyroid function (thyrotropin [TSH], free triiodothyronine [FT(3)], and free thyroxine [FT(4)]) and serum autoantibodies to thyroperoxidase (anti-TPOAb) were evaluated from blood samples. Thyroid structure and size were measured by ultrasound. RESULTS: A reference population was selected comprising 1488 persons (825 men) by excluding subjects with known thyroid diseases, and with yet unknown thyroid disorders such as goitre, inhomogeneous thyroid pattern, nodules, hypoechogenicity and anti-TPOAb seropositivity. Reference intervals for serum TSH, FT(3), and FT(4) were 0.25-2.12 mIU/L, 3.8-7.0 pmol/L, and 8.3-18.9 pmol/L, respectively. Reference serum TSH levels were not comparable to the reference values that were recently established for the U.S. population and most reference values slightly differed from the reference values provided by the manufacturers. CONCLUSIONS: The reference ranges of thyroid function tests in this formerly iodine-deficient region are distinct from the reference ranges that were established in areas with iodine sufficiency. Creating a reference population in the present setting should include thyroid ultrasound in order to exclude yet undiagnosed thyroid disorders.
Reduced bone mass is one of the main risk factors for fracture. An individual classification of future fracture risk can be made by relating bone mass to age- and sex-specific reference values. Since both bone mass and fracture incidence seem to be different in different populations, population-specific reference values should be studied before applying the reference values should by the manufacturers of the various types of measuring equipment. Using Lunar DPX-1, we measured bone mineral density (BMD) of the lumbar spine, femoral neck and total body in 225 women and 160 men in the age group 20-80 years, all of them from Oslo. The values were higher for men than for women. In the women the annual loss of bone increased after the age of 50 years in the lumbar spine and total skeleton, but the menopause appeared to have no effect for the femoral neck. Although the age- and sex-specific BMD differed very little from the reference values reported from Sweden and Finland, small differences in mean values and standard deviation between reference materials could create important differences in individual risk calculations if T-scores (deviation from mean value of premenopausal women calculated as standard deviation units) are used.
Standards are used in DNA cytophotometry to determine the diploid reference value. Fixation and staining protocols have to be standardized because numerous sources of variation influence staining intensity of DNA. When Feulgen stained imprints of rat liver cell nuclei are used as an external DNA standard a significant difference of reference value of up to 60% between imprints, from the same liver and with all sources of variation minimized, is demonstrated. Different possible sources of intra-imprint variation were examined but its exact nature remains unknown. Due to this inter-imprint variation, the DNA-reference value from a single liver imprint is only an approximation with unknown error of the true diploid reference value. By drawing an aselective random sample of N diploid cells in M imprints the sampling distribution of TIOD (mean Total Integrated Optical Density) will have its expectation identical to the diploid reference value and is approached by TIOD (mean TIOD) with the confidence interval defined by the number, M, of imprints measured. The use of TIOD as an estimate of diploid reference value with known precision is proposed as a first approach for the definition of a standard for DNA measurements.
12 pregnant females in the last trimester were subjected to serial amniocentesis. Although there was medical indication for amniocentesis the pregnancies were normal. All samples were evaluated with four different methods. We used two physical (Wilhelmy balance and foam test) and two chemical (L/S ratio densitometrically and planimetrically measured) methods. The Curves of individual pregnancies were compared with the reference values of 109 samples of amniotic liquid of uncomplicated pregnancies. Reference values for the various techniques reported in the literature are generally based on aggregate data collected from a number of pregnant females, which are then consolidated to obtain mean values for each gestational week. We found a continuous rise of all parameters, both in the reference value and in eight individual pregnancies. Besides we found a strikingly extraordinary run of the curves in four individual pregnancies. Here we recognized a rapid ascent and descent of surfactant concentration within short periods, which were not identical with the reference values. All four methods showed results with a statistical significant conformity, only the foam test showed a little lower significance.
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The diffusing capacity, when normalized per liter of alveolar volume (DL,CO/VA) decreases in normal adults, whereas their total diffusing capacity (DL,CO) increases as alveolar volume (VA) increases. We studied these relationships in a group of normal children below 20 years of age. Diffusion variables were determined using the single breath technique. The effects of sex, age, and height on these relationships were estimated. DL,CO increased and DL,CO/VA decreased as alveolar volume increased. DL,CO and DL,CO/VA reference values at total lung capacity (TLC) appeared to be comparable to reference values at TLC in the literature. Reference values of DL,CO and DL,CO/VA derived from measurements at various alveolar volumes also predict similar values at TLC. The advantage of our reference equations is their applicability to patients with restrictive lung disease. Actual DL,CO/VA can be compared with reference DL,CO/VA at actual (restrictive) TLC instead of reference DL,CO/VA at reference TLC. This comparison extends the evaluation of a diffusion disorder.
We evaluated the precision and accuracy of monitoring of the blood glucose level in the laboratory and at the bedside with one of four glucose meters by an experienced operator and by 39 nurses in a teaching hospital. For precision studies aqueous quality control materials were used. A total of 85 blood samples were tested. The precision of the glucose meters (expressed as the coefficient of variation [CV]) in the hands of the experienced operator ranged from 6.7% to 11.1%. The correlation between the values obtained by the experienced operator and the reference values obtained in the laboratory was high (0.95 to 0.98). The precision of the values obtained by the nurses using the meters ranged from 13.7% on medical wards to 45.7% in the intensive care unit (ICU). The correlation between these values and those obtained in the central laboratory ranged from 0.72 to 0.82. Twenty-four percent of the glucose values determined on medical wards and 62% of those determined in the ICU deviated from the reference value by at least 20%. Of the 85 patients 12 (14%) would have received different insulin dosages had the reference value been available at the same time as the glucose meter reading: in 3 of the patients the discrepancy was 6 units of insulin or greater. Continuous quality control of bedside monitoring of the blood glucose level is needed. In addition, personnel who use glucose meters should receive adequate training.
In comparison with the environmental compartments air and water, soil is an extremely complicated system, because properties of the soil and chemical, physical and biological characteristics vary greatly between different soil systems. This makes the development of general rules for quantitative evaluation of soil quality impossible. The large variation between the buffering capacities of various soils for different compounds also complicates the question. In The Netherlands, a system of reference values for various compounds has been developed, these reference values reflect situations in which there is a low degree of contamination. For heavy metals, these reference values consist of sliding scales incorporating the influence of a soil's clay and organic matter content. Examples for derivation of effect-based soil quality standards are briefly described.
BACKGROUND: Determination of fecal pancreatic elastase 1 (E1) is a reliable and noninvasive test of exocrine pancreatic function. Adult reference values of greater than 200 microg E1/g feces do not seem to be applicable to early infancy because of immature pancreatic function. Because reference values for infants do not exist, the current study was aimed to define reference values for preterm and term infants up to 12 months of age. METHODS: The authors measured pancreatic E1 concentration in feces of 148 infants up to 12 months of age. Infants with known bowel or pancreatic disorders were excluded from the study. RESULTS: The authors found that 96.8% of all children had E1 concentrations greater than an adult lower limit after 2 weeks of life, independent of gestational age. Up to 48 hours after birth, none of the preterm infants had an E1 concentration of greater than 30 microg/g meconium, whereas 43% of the term infants had normal adult values. CONCLUSIONS: The adult reference value for pancreatic E1 of greater than 200 microg/g feces can be applied to infants older than 2 weeks, independent of gestational age, birth weight, and the type of nutrition.
OBJECTIVE: To evaluate initially the feasibility and accuracy of real-time three-dimensional echocardiography (RT-3DE) for quantifying right ventricular (RV) volume and wall mass in an in vitro experimental study. METHODS: In ten excised porcine hearts, measurements of RV volume and free wall mass with RT-3DE were outlined and calculated by 2-, 4-, 8- and 16-plane methods with Tom Tec 4D Cardio-View RT 1.0. The results were compared with those of 2D length method and 2D biplane Simpson method. The values of RV silicone latex cast and free wall mass measured by water displacement were served as reference values. RESULTS: RV shapes of excised porcine hearts with RT-3DE were similar to those of the actual anatomic RVs and RV silicone latex casts. From the findings of analysis of variance and Student-Newman-Keuls test, there was no significant difference between measurements of RV volume with RT-3DE 16-plane (mean 64.05 ml), 8-plane (61.83 ml) and the reference values of RV silicone latex casts (62.94 ml). No significant difference was found between measurements of RV free wall mass with 16-plane (72.81 g), 8-plane (71.05 g) and the reference values of RV free wall masses (76.21 g). However, there was significant difference between measurements of RV volume and free wall mass with 2-plane, 2D biplane Simpson method and the reference values. Furthermore, the measurements of RV volume and free wall mass with 16-plane and 8-plane were better correlated with the reference values than those with 4-plane and 2D length method. CONCLUSIONS: RT-3DE will be a valuable technique for quantifying irregular crescentic RV volume and wall mass.
Levels of plasma cholinesterase in Colombian working-class populations Reference values for plasma cholinesterase (EC 3.1.1.8) are not available for Colombian populations. A representative sample of a working-class population was used to establish these values to provide reference data for use by the social security system. Two working-class populations were sampled from the Aburrá Valley (Aburrá) and eastern Antioquia (Oriente). Cholinesterase activity was measured in 827 workers, with ages spanning 18-49 years, 415 from Aburrá and 412 people from Oriente. Three methods were used to measure cholinesterase: Michel, EQM and Monotest The average values by Michel and EQM were not statistically different between regions (Michel: Aburrá, 1.11, and East, 1.13 deltas pH/hora; EQM: Aburrá, 2.55, and Oriente, 2.48 U/ml). By the Monotest, the enzyme average was statistically higher in Aburra than in Oriente (5,743 and 5,459 U/L respectively; p = 0 .012). By region and technique, men had significantly higher enzymatic levels than women. Within both regions and sexes, no statistically significant difference among the three aged groups was noted. Our obtained Colombian values differed significantly from foreign reference values: Michel and Monotest levels were higher and EQM levels were lower. For making clinical and epidemiologic decisions in Colombia related to these data, the values obtained for the Colombian populations are preferred over values derived from external sources.
Lengths and weights have been measured every month from birth to two years of age in 48 Aboriginal children born into six remote communities in the Kimberley region in the far north of Western Australia. Birthweights, on average, were slightly less than international reference values but growth rates in the first 3 months of life exceeded those reference values. However, between 3 and 6 months of age rates of weight gain and linear growth fell below those expected at that age and after 9 months of age Aboriginal infants were lighter than reference values and remained so throughout the first two years of life. By 2 years of age the Kimberley children were more than 1 kg lighter and 4.5 cm (boys) and 3.6 cm (girls) shorter than the international reference values. Monthly means and standard deviations for weight and length velocities are given. Environmental factors, particularly infections and inadequate nutrition, are important contributors to impaired growth in Aboriginal infants and young children.
We calculated reference values for arterial blood gases at different altitudes in Mexico assuming that sea level PaCO2 is 40 Torr, and in Mexico City (2.24 km. above the sea level) is 31.13 Torr, average of reported reference values. With the previous two points, it is possible to calculate a linear regression: PaCO2 = 40-3.96(altitude in km.). The equation is very similar to that calculated from reports in alveolar gas in North-Americans (Fitzgerald < 5 km): PACO2 = 39.3-3.11(altitude in km), and from subjects acclimatized to acute altitude exposure (< 5 km): PACO2 = 38.3-2.5 (altitude in km). It is also similar to a alinear equation that can be calculated assuming that hyperventilation in permanent habitants of moderate altitudes is inversely proportional to inspired molar concentration of O2: PaCO2 = PIO2/3.74. On the other hand, the equation is very different than that obtained from Andean natives (Hurtado): PaCO2 = 40.4-1.35(altitude in km). The proposed linear equation for Mexico gives very similar results (< 2 Torr difference) than a complex curvilinear equation by Morris et al. appropriate only up to 2.3 km. Evidence from acute exposure to altitude (acclimatized) and in North-Americans (alveolar gas) supports a reasonably accurate linear relationship up to 4 km. and also that the increase in ventilation in response to moderate altitudes in adult permanent residents is inversely proportional to molar concentration of O2. PAO2 was calculated with alveolar gas equation and resting the P(A-a)O2 we obtained PaO2. In conclusion, according to reference values in Mexico City, PaCO2 decreases about 4 Torr per km of altitude above the sea level. The decrease is similar to that reported in North-Americans and in acute exposure to altitude (acclimatized), but much less than that reported in native Peruvians. Ventilation is inversely proportional to the molar concentration of O2 at least up to an altitude where SaO2 is at or above 90%.
OBJECTIVE: To evaluate the clinical and analytic accuracy of 5 portable blood glucose meters (PBGM) in cats, with emphasis on the detection of potential sources of error. ANIMALS: 200 cats. PROCEDURE: Venous blood glucose readings from 5 PBGM were compared with the results of a hexokinase reference method. Agreement among methods was determined by error grid analysis and statistical methods. RESULTS: A total of 2,975 PBGM readings and 513 reference values were analyzed. The accuracy of the PBGM varied in different glycemic ranges. The largest differences between PBGM readings and reference values were in the high glycemic range; 4 PBGM underestimated and 1 PBGM overestimated the reference values in most instances. In the low and reference glycemic ranges, the absolute differences between PBGM readings and reference values were small. Despite the analytic differences in accuracy, 4 PBGM had 100% and 1 PBGM had 98.7% of readings in the clinically acceptable values of the error grid analysis. Within- and between-day precisions were good for all PBGM. Significant differences were not detected between readings of EDTA and lithium-heparinized blood and fresh blood without anticoagulant. Compared with these blood types, 1 PBGM had significantly different readings with fluoride anticoagulated blood. In blood samples with a low Hct, all PBGM overestimated glucose concentrations. Sample volumes < 3 microl resulted in inaccurate measurements in 3 PBGM. CONCLUSIONS AND CLINICAL RELEVANCE: Performance varied among the 5 PBGM analyzed; however, all PBGM were deemed acceptable for clinical use in cats.
OBJECTIVES: To describe age-related systolic blood pressures and pulse rates in children following blunt injury. To compare these variables with standard reference values for uninjured children at rest and with reference ranges from the Advanced Paediatric Life Support (APLS) guidelines. DESIGN: Secondary analysis of a prospective cohort. SETTING: Emergency departments throughout England and Wales. PARTICIPANTS: 12906 children presenting with acute blunt traumatic injury from August 1989 to September 1998. MAIN OUTCOME MEASURES: Systolic blood pressure and pulse rate on arrival. RESULTS: Injured children had higher systolic blood pressures than the standard quoted 'norms'. Standard reference values of systolic blood pressure for children at rest always appeared below the 50th percentile for our cohort of injured children (range 7th-27th percentiles). Pulse rates for children at rest were always towards the mid-range for injured children (range 41st-54th percentiles). These results appeared unrelated to injury severity. Age related APLS reference ranges for systolic blood pressure and pulse rate resembled the standard reference values for uninjured children at rest. CONCLUSIONS: Injured children have a relative systolic hypertension compared with children at rest. Pulse rates in the two groups are comparable. Following injury, children with apparently 'normal' age-specific systolic blood pressures on arrival in the Emergency Department are relatively hypotensive and should be carefully assessed.