Schwartz Formula: Is One k-Coefficient Adequate for All Children?

Background/Objective

Plasma-creatinine-based equations to estimate the glomerular filtration rate are recommended by several clinical guidelines. In 2009, Schwartz et al. adapted the traditional Schwartz equation to children and adolescents but did not find different k-coefficients between children and adolescents (k = 36.5 for all patients). We reevaluated the coefficient of the 2009-Schwartz formula according to sex and age in a pediatric population.

Patients/Methods

We used linear mixed-effects models to reestimate the 2009-Schwartz k-coefficient in 360 consecutive French subjects aged 1 to 18 years referred to a single centre between July 2003 and July 2010 (965 measurements). We assessed the agreement between the estimated glomerular filtration rate obtained with the new formula (called Schwartz-Lyon) and the rate measured by inulin clearance. We then compared this agreement to the one between the measured glomerular filtration rate and 2009-Schwartz formula, first in the French then in a Swedish cohort.

Results

In Schwartz-Lyon formula, k was estimated at 32.5 in boys <13 years and all girls and at 36.5 in boys aged ≥13 years. The performance of this formula was higher than that of 2009-Schwartz formula in children <13 years. This was first supported by a statistically significant reduction of the overestimation of the measured glomerular filtration rate in both cohorts, by better 10% and 30% accuracies, and by a better concordance correlation coefficient.

Conclusions

The performance and simplicity of Schwartz formula are strong arguments for its routine use in children and adolescents. The specific coefficient for children aged <13 years further improves this performance.     

Analysis of Bitter Orange Petitgrain Essential Oil by Combined Gas Chromatography-Mass Spectrometry

Candida catenulata CBS 1904, the previous type strain of C. ravautii, was selected as the best strain for the production of threo-O_s-isocitric acid from water-insoluble carbon sources, non-carbohydrates. The addition of surfactants, lipophilic polyoxyethylene nonyl phenyl ethers, was essential for the acid production, because the cell surface of the strain was less lipophilic. «-Alkanes, ranging from C_n to C_l4, gave the acid in high yields. The acid was produced in ajar fermentor in an about 90% yield on a weight basis as to «-tetradecane supplied. The acid was easily recovered, as crystals of its monopotassium salt, from the concentrated culture broth filtrate.     

Essential Oil Variability and Biological Activities of Tetraclinis articulata (Vahl) Mast. Wood According to the Extraction Time

In the present work, the hydrodistillation (HD) and microwave‐assisted hydrodistillation (MAHD) kinetics of essential oil (EO) extracted from Tetraclinis articulata (Vahl ) Mast. wood was conducted, in order to assess the impact of extraction time and technique on chemical composition and biological activities. Gas chromatography (GC) and GC/mass spectrometry analyses showed significant differences between the extracted EOs, where each family class or component presents a specific kinetic according to extraction time, technique and especially for the major components: camphene, linalool, cedrol, carvacrol and α‐acorenol. Furthermore, our findings showed a high variability for both antioxidant and anti‐inflammatory activities, where each activity has a specific effect according to extraction time and technique. The highlighted variability reflects the high impact of extraction time and technique on chemical composition and biological activities, which led to conclude that we should select EOs to be investigated carefully depending on extraction time and technique, in order to isolate the bioactive components or to have the best quality of EO in terms of biological activities and preventive effects in food.     

Antigravity suit inflation: kidney function and cardiovascular and hormonal responses in men

To investigate the effects of lower body positive pressure (LBPP) on kidney function while controlling certain cardiovascular and endocrine responses, seven men [35 +/- 2 (SE) yr] underwent 30 min of sitting and then 4.5 h of 70 degrees head-up tilt. An antigravity suit was applied (60 Torr legs, 30 Torr abdomen) during the last 3 h of tilt. A similar noninflation experiment was conducted where the suited subjects were tilted for 3.5 h. To provide adequate urine flow, the subjects were hydrated during the course of both experiments. Immediately after inflation, mean arterial pressure increased by 8 +/- 3 Torr and pulse rate decreased by 16 +/- 3 beats/min. Plasma renin activity and aldosterone were maximally suppressed (P less than 0.05) after 2.5 h of inflation. Plasma vasopressin decreased by 40-50% (P less than 0.05) and plasma sodium and potassium remained unchanged during both experiments. Glomerular filtration rate was not increased significantly by inflation, whereas inflation induced marked increases (P less than 0.05) in effective renal plasma flow (ERPF), urine flow, osmolar and free water clearances, and total and fractional sodium excretion. No such changes occurred during control. Thus, LBPP induces 1) a significant increase in ERPF and 2) significant changes in kidney excretory patterns similar to those observed during water immersion or the early phase of bed rest, situations that also result in central vascular volume expansion.     

Chemical Variability and Biological Activities of Brassica rapa var. rapifera Parts Essential Oils Depending on Geographic Variation and Extraction Technique

In the present work, the Brassica rapa var. rapifera parts essential oils and their antioxidant and antimicrobial activities were investigated for the first time depending on geographic origin and extraction technique. Gas‐chromatography (GC) and GC/mass spectrometry (MS) analyses showed several constituents, including alcohols, aldehydes, esters, ketones, norisoprenoids, terpenic, nitrogen and sulphur compounds, totalizing 38 and 41 compounds in leaves and root essential oils, respectively. Nitrogen compounds were the main volatiles in leaves essential oils and sulphur compounds were the main volatiles in root essential oils. Qualitative and quantitative differences were found among B. rapa var. rapifera parts essential oils collected from different locations and extracted by hydrodistillation and microwave‐assisted hydrodistillation techniques. Furthermore, our findings showed a high variability for both antioxidant and antimicrobial activities. The highlighted variability reflects the high impact of plant part, geographic variation and extraction technique on chemical composition and biological activities, which led to conclude that we should select essential oils to be investigated carefully depending on these factors, in order to isolate the bioactive components or to have the best quality of essential oil in terms of biological activities and preventive effects in food.     

The Relationship between Renal Function and Plasma Concentration of the Cachectic Factor Zinc-Alpha2-Glycoprotein (ZAG) in Adult Patients with Chronic Kidney Disease

Zinc-α2-glycoprotein (ZAG), a potent cachectic factor, is increased in patients undergoing maintenance dialysis. However, there is no data for patients before initiation of renal replacement therapy. The purpose of the present study was to assess the relationship between plasma ZAG concentration and renal function in patients with a large range of glomerular filtration rate (GFR). Plasma ZAG concentration and its relationship to GFR were investigated in 71 patients with a chronic kidney disease (CKD) stage 1 to 5, 17 chronic hemodialysis (HD), 8 peritoneal dialysis (PD) and 18 non-CKD patients. Plasma ZAG concentration was 2.3-fold higher in CKD stage 5 patients and 3-fold higher in HD and PD patients compared to non-CKD controls (P<0.01). The hemodialysis session further increased plasma ZAG concentration (+39%, P<0.01). An inverse relationship was found between ZAG levels and plasma protein (r_s = −0.284; P<0.01), albumin (r_s = −0.282, P<0.05), hemoglobin (r_s = −0.267, P<0.05) and HDL-cholesterol (r_s = −0.264, P<0.05) and a positive correlation were seen with plasma urea (r_s = 0.283; P<0.01). In multiple regression analyses, plasma urea and HDL-cholesterol were the only variables associated with plasma ZAG (r² = 0.406, P<0.001). In CKD-5 patients, plasma accumulation of ZAG was not correlated with protein energy wasting. Further prospective studies are however needed to better elucidate the potential role of ZAG in end-stage renal disease.     

Essential Oil Variability of Tetraclinis articulata (Vahl) Mast. Parts During Its Phenological Cycle and Incidence on the Antioxidant and Antimicrobial Activities

The impact of phenological stages (vegetative, flowering and fruiting stages) on chemical composition, antioxidant, and antimicrobial activities of Tetraclinis articulata (Vahl ) Mast . parts essential oils were investigated for the first time. GC and GC/MS analyses pointed to a quantitative variability of components; terpene hydrocarbons derivatives, represented by α‐pinene (16.38 ± 0.19 – 31.78 ± 0.35%) and limonene (3.41 ± 0.07 – 9.49 ± 0.14%) as major components, predominate at the vegetative stage, whereas oxygenated derivatives, represented by camphor (16.11 ± 0.23 – 26.17 ± 0.29%) and bornyl acetate (15.21 ± 0.21 – 27.33 ± 0.33%) as major components, predominate at the fruiting stage. Furthermore, our findings showed that the plant parts collected at the fruiting stage possess the highest antioxidant activity and the best antimicrobial activity against the tested microorganisms, than plant parts collected at the vegetative and flowering stages. This highlighted variability reflects the high impact of phenological cycle on chemical composition and biological activities, which led to conclude that we should select essential oils to be investigated carefully depending on phenological stage, in order to have the highest effectiveness of essential oil in terms of biological activities for human health purposes.     

Adaptation of an enzymatic polyfructosan assay to clinical practice

Inulin or polyfructosan clearance is regarded as the most accurate method of assessing the glomerular filtration rate. We propose an enzymatic method of polyfructosan determination based on the hydrolysis of polyfructosan into fructose by inulinase and the elimination of the interfering quantity of glucose by glucose oxidase. This spectrophotometric microplate formatted assay, which demonstrated very good specificity and reproducibility (within-run precision <1% and between-run precision <3.5%), is cheap and simple to perform and can be used by all analytical laboratories and in all clinical conditions.