Reference intervals of aortic pulse wave velocity assessed with an oscillometric device in healthy children and adolescents from Argentina

Age-related reference intervals (RIs) of aortic pulse wave velocity (Ao-PWV) obtained from a large healthy population are lacking in South America. The aims of this study were to determine Ao-PWV RIs in a cohort of healthy children and adolescents from Argentina and to generate year-to-year percentile curves.

Ao-PWV was measured in 1000 healthy subjects non-exposed to traditional cardiovascular risk factors (Age: 10–22 y. o., 56% males). First, we evaluated if RIs for males and females were necessaries (correlation and covariate analysis). Second, mean (M) and standard deviation (SD) age-related equations were obtained for cf-PWV, using parametric regression methods based on fractional polynomials. Third, age-specific (year to year) percentiles curves (for all, males and females children and adolescents) were generated using the standard normal distribution. They were, age-specific 1st, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th and 99th percentile curves and values.

After covariate analysis (i.e., adjusting by age, jugulum-symphysis distance, body weight and height), specific RIs for males and females of children and adolescents were evidenced as necessaries. The equations were

For all subjects:

Ao-PWV_Mean = 4.98 + 12.86x10^?5 Age³.

Ao-PWV_SD = 0.47 + 21.00x10^?6Age³.

For girls:

Ao-PWV_Mean = 5.07 + 10.23x10^?5Age³.

Ao-PWV_SD = 0.50 + 10.00x10^?6Age³.

For boys:

Ao-PWV_Mean = 4.87 + 15.81x10^?5Age³.

Ao-PWV_SD = 0.46 + 22.34x10^?6Age³.

Our study provides the largest database to-date concerning Ao-PWV in healthy children and adolescents in Argentina. Age-related equations (M and SD values) for Ao-PWV are reported by the first time. Specific RIs and percentiles of Ao-PWV are now available according to age and sex for an Argentinian population.     

Heat-assisted slurry sampling GFAAS method for determination of lead in food standard reference materials

A valid method based on heat-assisted slurry sampling graphic furnace atomic absorption spectrometry (HASS-GFAAS) was developed for the accurate determination of trace Pb in food standard reference materials (SRMs). The HASS technique significantly improved Pb recovery and precision compared to conventional slurry sampling techniques. The optimized HASS procedure was performed as follows: first, the sample (particle size ≤ 150 μm) was diluted with 0.05% (v/v) Triton X-100 containing 2% HNO₃ and 1% H₂O₂ followed by heating for 20 min at 120 °C on a heating block. Next, the obtained slurry was sonicated in an autosampler cup, and finally, the slurry was introduced into a graphite tube and analyzed by the GFAAS with a Pb electrodeless discharge lamp (EDL). Calibration with aqueous standard solutions was used for Pb determination in food samples. The characteristic mass and limit of detection for Pb based on the integrated absorbance for a 2% (m/v) sample were 12 ± 0.6 pg and 0.003 mg kg⁻¹, respectively. The accuracy (95.1–102% recovery) and good precision (0.1–3.6%) of this procedure are illustrated by the results obtained for the 12 food reference materials. The proposed method is suitable for determination of trace Pb in solid food samples.     

Age‐specific pediatric reference ranges for immunoglobulins and complement proteins on the Optilite™ automated turbidimetric analyzer

Background

Measurement of immunoglobulins and complement proteins are frontline tests used in the assessment of immune system integrity, and reference values can vary with age. Their measurement provides an insight into the function of the innate and adaptive immune systems.

Methods

We generated pediatric reference ranges for IgG, IgA, IgM, IgD, the IgG and IgA subclasses, and C3 and C4 using the Optilite™ turbidimetric analyzer.

Results

The concentrations of IgG, IgA, and IgD showed an increase with age, as expected, while IgM remained stable between the age groups. For the IgG subclasses, no significant differences were observed in IgG1 or IgG3, while IgG2 and IgG4 concentrations increased steadily with age. The concentration of IgG2 plateaued at 15‐18 years, while IgG4 plateaued at 10‐14 years. The trend of concentrations across all groups was IgG1 > IgG2 > IgG3 > IgG4. For both IgA1 and IgA2, concentrations increased significantly with age, plateauing at 15‐18 years. The median IgA1 concentration was greater than IgA2 across all groups. There was a good correlation between the total IgG or IgA concentration and summation of their subclasses (R² = 0.89, P < .0001, slope y = 0.98x + 14.51 mg/dL and R² = 0.91, P < .0001, slope y = 1.35x‐3.28 mg/dL, respectively). The concentration of C3 and C4 remained stable across the groups, with no significant differences observed.

Conclusion

We have generated age‐specific reference ranges in healthy children for C3, C4, IgG, IgA, IgM, IgD and the IgG and IgA subclasses using the Optilite^™ turbidimetric analyzer. These ranges will help identify individuals with abnormal concentrations, thus will aid in the diagnosis of both primary and secondary immunological disorders.

     

Maternal thyroid‐stimulating hormone reference ranges for first trimester screening from 11 to 14 weeks of gestation

Background

To establish maternal thyroid‐stimulating hormone (TSH) reference ranges for first trimester screening from 11 + 0 to 13 + 6 weeks of gestation.

Methods

A total of 10 592 singleton and 201 twin consecutive Caucasian pregnant women who underwent simultaneously prenatal first trimester Down's syndrome screening and thyroid function screening from January 2010 to November 2017 were included in the study. Women with positive antithyroid peroxidase antibody (TPOAb) and positive personal history of thyroid disease were previously excluded. TSH was measured by immunochemiluminescent assay on ci 16200 Abbott Architect analyzer. Nonparametric percentile method (also known as CLSI C28.A3) was used for the determination of reference ranges.

Results

We established reference ranges of TSH for the period of gestation from 11 + 0 to 13 + 6 weeks of pregnancy as 0.16‐3.43 mU/L for singleton Caucasian pregnancies and 0.02‐2.95 mU/L for twin Caucasian pregnancies. The median (IQR) of TSH for singleton pregnancies was higher than that for twin pregnancies (1.25 mU/L (0.83‐1.81) vs 0.84 (0.37‐1.47), respectively; P < .0001).

Conclusions

Each first trimester screening center should be aware of which type of immunoassay their laboratory uses. TSH reference ranges in women during the first trimester of pregnancy are lower than those for general population. Twin pregnancies have lower TSH than singleton pregnancies.

     

Racial/Ethnic-Specific Reference Intervals for Common Laboratory Tests: A Comparison among Asians,Blacks, Hispanics,and White

Reference intervals (RIs) for common clinical laboratory tests are usually not developed separately for different subpopulations. The aim of this study was to investigate racial/ethnic differences in RIs of common biochemical and hematological laboratory tests using the National Health and Nutrition Examination Survey (NHANES) 2011–2012 data. This current study included 3,077 participants aged 18–65 years who reported their health status as “Excellent,” “Very good,” or “Good,” with known race/ethnicity as white, black, Hispanic, or Asian. Quantile regression analyses adjusted for sex were conducted to evaluate racial/ethnic differences in the normal ranges of 38 laboratory tests. Significant racial/ethnic differences were found in almost all laboratory tests. Compared to whites, the normal range for Asians significantly shifted to higher values in globulin and total protein and to lower values in creatinine, hematocrit, hemoglobin, mean cell hemoglobin, mean cell hemoglobin concentration, and mean platelet volume. These results indicate that racial/ethnic subpopulations have unique distributions in the labortoary tests and race/ethnicity may need to be incorporated in the development of their RIs. Establishment of racial/ethnic-specific RIs may have significant clinical and public health implication for more accurate disease diagnosis and appropriate treatment to improve quality of patient care, especially for a state with diverse racial/ethnic subpopuations such as Hawai‘i.     

Quantitative evaluation of the pulmonary microdistribution of TiO2 nanoparticles using X‐ray fluorescence microscopy after intratracheal administration with a microsprayer in rats

The unevenness of pulmonary nanoparticle (NP) distribution, which hinders the establishment of an absolute dose–response relationship, has been described as one of the limitations of intratracheal administration techniques for toxicological assessment of inhaled NPs. Quantification of the NP microdistribution would facilitate the establishment of a concentration–response relationship in localized regions of the lung; however, such quantitative methods have not been reported. Here, we established a quantitative method for evaluating pulmonary TiO₂ NP microdistribution in rats using X‐ray fluorescence microscopy. Ti intensity in lung sections from rats intratracheally administered 10 mg kg^–1 TiO₂ NPs with a microsprayer was measured using X‐ray fluorescence with a 100 µm beam size. Ti reference samples were prepared by dropping different concentrations of Ti solutions on glass slide or lung sections of untreated rat. Ti intensity increased linearly with Ti content in the reference samples on both substrates. The detection limit of TiO₂ was estimated to be 6.3 ng mm^–2. The reproducibility was confirmed for measurements done in the short‐ (2 weeks) and long‐term (6 months). The quantitative results of TiO₂ NP microdistribution suggested that more TiO₂ NPs were distributed in the right caudal and accessory lobes, which are located downstream of the administration direction of the NP suspension, and the lower portion of each lobe. The detection rates of TiO₂ NPs were 16.6–25.0%, 5.19–15.6%, 28.6–39.2%, 21.4–38.7% and 10.6–23.2% for lung sections from the right cranial, middle, caudal, accessory and left lobes, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Hyposelenaemia: patients with gastrointestinal diseases are at risk

A retrospective study of serum selenium determinations performed in a hospital laboratory revealed 47 cases of hyposelenaemia (defined as a serum selenium level below 0.74 mumol l-1). Moderate hyposelenaemia (serum selenium 0.30-0.55 mumol l-1) was found in 11 patients and seven of these suffered from gastrointestinal diseases. Furthermore severe hyposelenaemia (serum selenium below 0.30 mumol l-1) was detected in three patients, who were all affected by gastrointestinal disease. We concluded that patients with gastrointestinal diseases are especially at risk of developing selenium deficiency and should be monitored by repeated determinations of serum selenium. Patients with moderate or severe hyposelenaemia should receive selenium treatment.     

Preparation,characterization and storage of human ferritin for use as a standard for the assay of serum ferritin

Summary. This paper describes studies on the source, preparation, characterization and storage of human ferritin for use as a standard for the immunoassay of serum ferritin. Ferritin was prepared from the liver or spleen by methods including either ultracentrifugation or cadmium sulphate crystallization. Preparations were characterized by polyacrylamide gel electrophoresis in dissociating and non-dissociating buffers, iso-electric focusing, analysis of amino acid composition and measurement of protein content. The protein content of solutions of liver or spleen ferritin may be determined by the method of Lowry with bovine serum albumin as standard. Lyophilization under carefully controlled conditions in buffer containing high concentrations of albumin provides a stable preparation of ferritin. Accelerated degradation and collaborative immunological studies of two lyophilized preparations of ferritin, one from liver and one from spleen, indicate that either is an acceptable reference material.     

Nasal airflow and resistance measured by active anterior rhinomanometry in healthy children and adolescents

Rhinomanometry allows objective assessment of nasal patency in pediatric patients with nasal and other respiratory problems. However, no reliable reference values are available in the pediatric age group. We measured nasal inspiratory airflow and nasal inspiratory resistance of the right and left nostrils (V'nar, V'nal, Rnar, and Rnal) and total nasal inspiratory flow and resistance (V'na and Rna) at a transnasal pressure of 150 Pa during quiet breathing in healthy children with a closed mouth by using active anterior rhinomanometry. Cross-sectional measurements were done in 192 healthy Caucasian children and adolescents free of nasal or other respiratory diseases (age, 2-19 years; body height, 94-190 cm; 95 boys and 97 girls). The values of V'na, V'nar, and V'nal increased significantly with an increase of body height or age (P<0.0001). Rna, Rnar, and Rnal significantly decreased with an increase of body height and age (P<0.0001). No significant statistical differences were found between boys and girls (P=0.11) or between right and left nostrils (P=0.07). V'nar and Rnar comprised 50.1%, and V'nal and Rnal 49.9%, of total V'na and Rna, respectively. Best-fit regression equations relating rhinomanometric parameters and body height or age were power functions. We obtained reference regression equations with upper and lower limits, and prepared tables listing reference (normal) values of rhinomanometric parameters in healthy pediatric Caucasian patients, against which patients with nasal obstruction can be compared.     

Carbon isotope ratio of endogenous urinary steroids of the Cuban population of athletes studied for doping purposes

The aim of this work was to validate the gas chromatography/combustion/isotope ratio mass spectrometry method in Havana Antidoping Laboratory and verify its implementation with a study of the Cuban population. The method was precise and accurate inside the linear working range; the limit of quantification and the uncertainty were compliant with TD2019IRMS. The study of the Cuban population showed no differences in δ¹³C values between females and males. Only three values of Δδ¹³C showed significant differences between sexes (PD‐T, OHA‐T, and 11‐keto‐Et‐T). The values of δ¹³C between ?17.8‰ and ?21.2‰ (upper and lower limits based on normal distribution) were consistent with other populations where C4 plant derivatives prevail in the diet.