A simple method for measurement of inulin in nanoliter samples using glass capillaries

Summary A simple method using glass capillaries instead of microcuvettes for measurement of inulin in nanoliter samples is given. Inulin was determined with anthron reagent (5 or 10 nl samples +3 l anthron reagent). Glass capillary tubes (o.d.=1 mm, i.d.=0.68 mm, length=150 mm) in which the chemical reaction took place during incubation at 56°C were directly introduced into the optical system of a Zeiss spectrophotometer PMQ II with sphere attachment and objective.Extinction was measured vertically to the axis of the capillary. The changes of extinction of 20 different capillaries with the blank at different positions was only 1.13×10^–3. The exactness of measurement in the concentration range of 100 200 400 750 1500 3000 mg-% inulin was for 5nl/3 l: 19.8 11.0 6.7 4.7 3.0 2.2%. 10nl/3 l: 13.0 8.4 5.1 3.9%.This method of measurement may also be applicable for other colorimetric reactions with nanoliter samples.This work was supported by Fonds zur Förderung der wissenschaftlichen Forschung.     

Comparison of Cystatin C,Creatinine and Creatinine Clearance vs. GFR for Detection of Renal Failure in Renal Transplant Patients

Background: Serum cystatin C (Scyst) has been suggested as an alternative index of glomerular filtration rate (GFR) and could be useful in renal transplant patients. Methods: In a 60‐subject cohort (40 ± 12 years old), we compared the simultaneous measurements of Scyst, serum creatinine (Screat), creatinine clearance (Ccreat), Cockcroft and Gault's estimated clearance (Ccg) and GFR measured using inulin clearance (Cin). Receiver operating characteristic (ROC) analysis was performed using two Cin cut‐off (60 and 90 mL/min/1.73 m²). Results: A significant correlation was found among Cin on one hand and 1/Scyst, Ccreat, 1/Screat and Ccg on the other hand. Best fits (sensitivity/specificity) at 90 mL/min/1.73 m² were 1.18 mg/L (0.72/0.80) for Scyst, 1.32 mg/dL (0.67/0.90) for Screat, 77 mL/min (0.80/0.70) for Ccg and 104 mL/min (0.88/0.80) for Ccreat. The areas under the ROC curves were not significantly different. Conclusions: This study provides cut‐off values for Screat and Ccg for detection of renal failure in renal transplant patients. However, the results also suggest that Scyst is not a more sensitive marker than Screat or Ccg for detecting renal failure in renal transplant patients.     

In vitro activities of inulin fermentation products to HCT-116 cells enhanced by the cooperation between exogenous strains and adult faecal microbiota

Inulin was fermented by adult faecal microbiota and 10 exogenous strains for 24 or 48?h. The contents of acetate, propionate, butyrate and lactate were quantified in the fermented products, and the growth-inhibitory and apoptosis-inducing effects on a human colon cell line (HCT-116 cells) were assessed. Most of these strains increased contents of acetate, propionate and butyrate, and promoted lactate conversion. Correlation analysis suggested that butyrate and lactate in the fermentation products were positively and negatively correlated with the measured inhibition ratios (p?via inducing DNA fragmentation and increasing total apoptotic populations in the treated cells. Moreover, the fermentation products with higher growth-inhibitory activities demonstrated the increased apoptosis-inducing properties. In conclusion, these strains could cooperate with adult faecal microbiota to confer inulin fermentation products with higher anti-colon cancer activity.     

Impact of dietary ingredients on the interpretation of various fecal parameters in rats fed inulin

In the present study, the influences of diets (i.e. chow and AIN-93 diets) on the interpretation of various fecal parameters including viable microbiota, moisture, weight, and short-chain fatty acids in rats fed different amounts of inulin (0.5–2 g/kg). Eight groups of rats (n = 8/group) were fed, for 4 weeks, chow or AIN-93 diets with or without inulin supplementation. Fecal samples were analyzed for different fecal parameters. After a 2-week adaptation, apparent differences in some fecal parameters were observed between the chow and AIN-93 diet groups. Throughout the 4-week intervention period, significantly (p < 0.05) higher Lactobacillus spp. counts, fecal moisture (∼2.7-fold), and fecal weight (∼5.8-fold) were observed with chow diet over AIN-93 diet. More specifically, significant elevations in the levels of Bifidobacterium spp., Lactobacillus spp., fecal moisture, and fecal weight could be observed at low-dose (0.5 g/kg) of inulin in chow diet groups, while most of these changes could merely be seen at medium-dose (1 g/kg) in AIN-93 diet groups. These results demonstrated that the choice of experimental diets would affect the comparison of fecal parameters as well as the interpretation of effective dosage of prebiotic in intestinal health assessments.     

Fructooligosaccharides exhibit more rapid fermentation than long-chain inulin in an in vitro fermentation system

This study investigated how chain length affects fermentation properties of fructooligosaccharides (FOSs) and inulin (IN). Chain lengths of FOSs and IN vary from an average degree of polymerization (DP) of 3 to greater than 20. Three samples classified as FOSs (samples A, B, and C) and 3 samples classified as IN (samples D, E, and F) were fermented via an in vitro batch method with human fecal inoculum as the source of microbes. Samples were removed at 0, 4, 8, 12, and 24 hours for total short-chain fatty acid (SCFA), acetate, propionate, and butyrate measurement via gas chromatography. Sample chain length did not affect SCFA concentrations in a predictable manner. Sample E (90%-94% DP > 10, 6%-10% DP = 1-2), a mixture of long-chain IN and short-chain FOS, produced significantly more total SCFA and acetate than the other samples. Sample F (DP > 20), the longest-chain IN, produced the lowest concentration of butyrate at 24 hours. The rate of FOS fermentation was higher than IN fermentation during 0 to 4 hours for all SCFAs, and the rate of IN fermentation was higher than FOS fermentation during 12 to 24 hours for all SCFAs. Chain length affects in vitro fermentability, with short chains being rapidly fermented and long chains being steadily fermented. Clinical studies should follow this work to verify if these differences exist in vivo.     

Skim soy protein enhances GFR as much as beefsteak protein in healthy human subjects

Background It has been reported that an acute load of beefsteak (200g) significantly enhanced the glomerular filtration rate (GFR; inulin clearance and creatinine clearance) in healthy human subjects compared to that in the same subjects in the fasted state. However, no comparative study of the effects of the same amount of vegetable protein on GFR has been reported to date.Methods We attempted to compare changes in the GFR (inulin clearance and creatinine clearance) in six healthy male subjects following consumption of the same amount of beefsteak or baked skim soy with soy sauce (protein, 86.9g) after fasting. The clearance study was performed by conventional methods. Inulin was measured by the anthrone method. Creatinine was measured by the Jaffe rate assay method. Amino-acid analysis of the beefsteak and baked skim soy with soy sauce was done by acid or hydroxide hydrolysis and an amino-acid analyzer.Results A significant enhancement of the GFR (both inulin clearance and creatinine clearance) was observed following acute loading with beefsteak or baked skim soy with soy sauce, compared to the GFR in the fasted state. No significant difference was observed between the results with beefsteak and the results with baked skim soy with soy sauce. Amino-acid analysis revealed that the total amount of three amino acids (glycine, alanine, and arginine; or serine, alanine, and proline) was almost identical in beefsteak (animal protein) and baked skim soy with soy sauce (vegetable protein).Conclusions The present study demonstrated that vegetable protein with the same amino-acid composition could enhance the GFR in healthy subjects as much as animal protein.     

HPLC-ELSD法测定菊粉中菊粉型果寡糖的含量

建立HPLC-ELSD法测定菊粉中9种蔗果寡糖的含量,色谱系统组成:色谱柱:Waters XBridge? Amide(4.6 mm×250 mm,5 μm);流动相:CH3CN-H2O,梯度洗脱;流速:1.2 mL/min;柱温:30℃;检测器:Agilent Technologies 380-ELSD,漂移管温度:...     

Creatinine for estimation of glomerular filtration rate

The aim of this study was to evaluate the plasma creatinine concentration (P_Cr) and creatinine clearance (C _Cr) for estimation of glomerular filtration rate (GFR). Inulin clearance (C _in) was used as the reference standard for GFR. Thirty-nine concurrentC _in andC _Cr studies provided data for comparingC _in with the measuredC _Cr and with the calculatedC _Cr (calc-C _Cr). (Calc-C _Cr=k·L/P_Cr, where L=height in centimeters and k is the proportionality constant.) Thirty-one children 5.3–20.8 years of age, withC _in ranging from 2.8 to 138.8 ml/min per 1.73 m², participated in these studies at The Children's Mercy Hosptial. The measuredC _Cr was 16.7±10.3 ml/min per 1.73 m² (P<0.001) greater than theC _in, and the calc-C _Cr overestimatedC _in by a mean of 31.6±20.8 ml/min per 1.73 m² (P<0.001). Although there is good correlation betweenC _in andC _Cr (r=0.96), andC _in and calc-C _Cr (r=0.90), the 95% confidence intervals are quite broad. Hence, theC _Cr and the calc-C _Cr, derived using Schwartz values for k, consistently overestimate GFR. However, if the k value in the equation GFR=k·L/P_Cr is derived from k=C _in/L, rather than from k=C _Cr·P_Cr/L, a more accurate estimate of GFR may be obtained.     

1,1′-Diisopropyl-2,4′-cyanine (disprocynium24), a potent uptake2 blocker, inhibits the renal excretion of catecholamines

1,1′-Diisopropyl-2,4′-cyanine (disprocynium24), a potent inhibitor of the extraneuronal monoamine transport system (uptake₂), was previously shown to reduce the clearance of catecholamines from plasma not only by blocking uptake₂ but presumably also by blocking organic cation transport. To provide more direct evidence for the latter conclusion, the present study was carried out in anaesthetized rabbits. It aimed at determining the effect of disprocynium24 on the renal excretion of catecholamines which is known to be, at least in part, a consequence of organic cation transport in the kidney. To this end, the plasma clearance due to renal excretion (Cl_u) of endogenous as well as infused ³H-labelled adrenaline, noradrenaline and dopamine was determined for 60-min periods of urine collection in rabbits treated either with disprocynium24 (270 nmol kg^-1 i.v followed by i.v. infusion of 80 nmol kg^-1 min^-1) or vehicle. Two groups of animals were studied: group I (monoamine oxidase and catechol-O-methyltransferase intact) and group II (monoamine oxidase and catechol-O-methyltransferase inhibited). A third group of animals with intact monoamine oxidase and catechol-O-methyltransferase was used to study the effect of disprocynium24 on the glomerular filtration rate (as determined by measuring the plasma clearance of inulin). In vehicle controls, Cl_u of endogenous adrenaline, noradrenaline and dopamine was 7.2, 5.2 and 153.6 ml kg^-1 min^-1, respectively, in group I and 10.4, 7.0 and 134.3 ml kg^-1 min^-1, respectively, in group II. Similar control values of Cl_u were obtained for infused ³H-adrenaline and ³H-noradrenaline, but not for infused ³H-dopamine; Cl_u of ³H-dopamine (4.9 ml kg^-1 min^-1 in group I and 15.4 ml kg^-1 min^-1 in group II) was considerably smaller than Cl_u of endogenous dopamine, indicating that most of the dopamine in urine (i.e., 98% in group I and 92% in group II) was derived from the kidneys rather than from the circulation. By contrast, only about one quarter of the noradrenaline in urine (32% in group I and 24% in group II) and none of the urinary adrenaline were of renal origin. In both groups, disprocynium24 markedly reduced the Cl_u of endogenous catecholamines (by 72-90%) and of infused ³H-catecholamines (by 49-69%). Moreover, it preferentially inhibited the renal excretion of those components of urinary dopamine and noradrenaline which were derived from the kidney. Therefore, disprocynium24 inhibits the tubular secretion of catecholamines and, hence, organic cation transport in the kidney. This conclusion was substantiated by the observation that disprocynium24 did not alter the glomerular filtration rate. Received: 6 February 1997 / Accepted: 12 April 1997     

Differences in the Effect of Hemodialysis on the Residual Clearance of Inulin, Endogenous Creatinine, and Urea

Abstract: In a group of 20 patients on regular hemodialysis treatment (HD), the residual glomerular filtration rate was examined before and 12 h after the end of HD. Inulin clearance decreased significantly after HD (p<0.001), whereas endogenous creatinine and urea clearance did not change. The results suggest that HD influences the function of residual nephrons.