A New Equation to Estimate Glomerular Filtration Rate in Chinese Elderly Population

Background

We sought to develop a new equation to estimate glomerular filtration rate (GFR) in Chinese elderly population.

Methods

A total of 668 Chinese elderly participants, including the development cohort (n = 433), the validation cohort (n = 235) were enrolled. The new equation using the generalized additive model, and age, gender, serum creatinine as predictor variables was developed and the performances was compared with the CKD-EPI equation.

Results

In the validation data set, both bias and precision were improved with the new equation, as compared with the CKD-EPI equation (median difference, −1.5 ml/min/1.73 m² vs. 7.4 ml/min/1.73 m² for the new equation and the CKD-EPI equation, [P<0.001]; interquartile range [IQR] for the difference, 16.2 ml/min/1.73 m² vs. 19.0 ml/min/1.73 m² [P<0.001]), as were accuracies (15% accuracy, 40.4% vs. 30.6% [P = 0.02]; 30% accuracy, 71.1% vs. 47.2%, [P<0.001]; 50% accuracy, 90.2% vs. 75.7%, [P<0.001]), allowing improvement in GFR categorization (GFR category misclassification rate, 37.4% vs. 53.2% [P = <0.001]).

Conclusions

A new equation was developed in Chinese elderly population. In the validation data set, the new equation performed better than the original CKD-EPI equation. The new equation needs further external validations. Calibration of the GFR referent standard to a more accurate one should be an useful way to improve the performance of GFR estimating equations.     

Purification and Characterization of High Molecular Mass and Low Molecular Mass Cystatin from Goat Brain

Cystatin are thiol proteinase inhibitors ubiquitously present in mammalian body and serve various important physiological functions. In the present study two cystatins were isolated from goat brain using alkaline treatment, ammonium sulphate fractionation, gel filtration and ion exchange chromatography. The high molecular mass cystatin of 70.8 kDa was named as HM-GBC (high molecular mass goat brain cystatin) and the low molecular mass cystatin of 12.72 kDa was named as LM-GBC (low molecular mass goat brain cystatin). The molecular mass determined by SDS-PAGE was found to be 70.8 and 12.88 kDa for HM-GBC and LM-GBC, respectively, however with gel filtration the masses were found to be 70.8 and 12.58 kDa. Both the cystatins were found to be stable in broad range of pH and temperature. HM-GBC was found to have 2% carbohydrate content while LM-GBC lacks any carbohydrate content. Both cystatins were found to be devoid of any sulphydryl content. Stoke's radii of 36 and 16 A, and diffusion coefficient of 6.189 x 10(-15) and 1.392 x 10(-14) cm(2)/s were calculated for HM-GBC and LM-GBC. K (i) values with papain were found to be 1.875 x 10(-8) and 3.125 x 10(-8) M for HM-GBC and LM-GBC, respectively. K (+1), K (-1) and half-life calculated along with K (i) values obtained showed that HM-GBC inhibited papain more specifically as compared to LM-GBC. The IC(50) values obtained for HM-GBC and LM-GBC also showed that HM-GBC binds more effectively to papain than LM-GBC. Ultraviolet and fluorescence spectra indicated that upon formation of papain-HM-GBC/LM-GBC complex there is significant conformational change after interaction in one or both the proteins of the complex.     

HIV Viremia and T-Cell Activation Differentially Affect the Performance of Glomerular Filtration Rate Equations Based on Creatinine and Cystatin C

Background

Serum creatinine and cystatin C are used as markers of glomerular filtration rate (GFR). The performance of these GFR markers relative to exogenously measured GFR (mGFR) in HIV-positive individuals is not well established.

Methods

We assessed the performance of the chronic kidney disease epidemiology collaboration equations based on serum concentrations of creatinine (eGFR_cr), cystatin C (eGFR_cys) and both biomarkers combined (eGFR_cr-cys) in 187 HIV-positive and 98 HIV-negative participants. Measured GFR was calculated by plasma iohexol clearance. Bias and accuracy were defined as the difference between eGFR and mGFR and the percentage of eGFR observations within 30% of mGFR, respectively. Activated CD4 and CD8 T-cells (CD38+ HLA-DR+) were measured by flow cytometry.

Results

The median mGFR was >100 ml/min/1.73 m² in both groups. All equations tended to be less accurate in HIV-positive than in HIV-negative subjects, with eGFR_cr-cys being the most accurate overall. In the HIV-positive group, eGFR_cys was significantly less accurate and more biased than eGFR_cr and eGFR_{cr_cys}. Additionally eGFR_cys bias and accuracy were strongly associated with use of antiretroviral therapy, HIV RNA suppression, and percentages of activated CD4 or CD8 T-cells. Hepatitis C seropositivity was associated with larger eGFR_cys bias in both HIV-positive and HIV-negative groups. In contrast, eGFR_cr accuracy and bias were not associated with HIV-related factors, T-cell activation, or hepatitis C.

Conclusions

The performance of eGFR_cys relative to mGFR was strongly correlated with HIV treatment factors and markers of T-cell activation, which may limit its usefulness as a GFR marker in this population.     

A New Functional Equation Analogous to CAUCHT-PEXIDER Functional Equation and its Application

The CAUCHY-PEXIDER functional equation H (x±y)=F(x) G(y) is generalized to the form H ((x^c±y^c)^1/c) = F(x) G(y), c≠0, assuming the function H(x) possesses a measurable majorant on a set of positive measure. The result is used to obtain a characterization of WEIBULL distribution. This functional equation is generalized to functions of vector variables.     

An Equation to Estimate the Concentration of Serum Apolipoprotein B

Background

Several large prospective studies have demonstrated that apolipoprotein B (apoB) has greater value in predicting cardiovascular risk than any other lipid measurements. Currently, however, serum apoB levels are not routinely measured, because of the additional cost. The aim of this study was to develop an equation to estimate apoB from conventional lipid measurements including total cholesterol, HDL cholesterol, and triglycerides.

Methods

Data from a total of 78,127 subjects (47,057 men and 31,070 women), aged 15 to 88 years (mean age 41.8 years) were reviewed to develop an apoB equation. Additional datasets from the same institution and the NHANES obtained in 2007–2008 were used for internal (n = 73,445) and external validation (n = 3,097), respectively.

Results

We developed an apoB equation based on a linear regression model that contains total cholesterol, triglycerides, and HDL cholesterol as terms (model 1). To more precisely estimate the serum apoB level, we adjusted mode1 1 using a cutoff serum triglyceride value of 270 mg/dl (model 2). Model 2 showed more randomly distributed residuals in patients with diabetes, atherogenic dyslipidemia, and those taking lipid-lowering agents than model 1. The residuals in the development, internal validation, and external validation datasets were also randomly distributed around 0 with no clear trends.

Conclusion

The new equation we developed to estimate serum apoB concentrations is accurate and can be used in diverse subgroups of patients including those with diabetes, atherogenic dyslipidemia, and those taking lipid-lowering agents.     

Use of Cystatin C and Serum Creatinine for the Diagnosis of Contrast-Induced Nephropathy in Patients Undergoing Contrast-Enhanced Computed Tomography at an Oncology Centre

ObjectiveOur aim was to assess renal function using as laboratory measurements serum creatinine and cystatin C concentrations before and after administration of low-osmolarity (nonionic) iodinated contrast medium in patients with cancer undergoing computed tomography (CT).MethodsThis prospective study included 400 oncologic outpatients. Serum creatinine and cystatin C concentrations were measured before and 72 h after contrast administration. Glomerular filtration rates (GFRs) were estimated using serum creatinine–based [Modification of Diet in Renal Disease (MDRD) and Cockroft-Gault and cystatin C based (Larsson) equations. Exploratory data analysis was performed. The nonparametric Wilcoxon test was used to compare pre and post contrast of test results and estimated clearance. The confidence interval used in the analysis was 95%.ResultsCompared with the pre-contrast values, the mean serum creatinine concentration was significantly higher and average GFRs estimated using MDRD and Cockcroft-Gault equations were significantly lower after the administration of contrast (p <0.001). It was also observed a significant increase after contrast in the concentration of Cystatin C (p = 0.015). In addition, a decrease in GFR estimated using the average Larsson (p = 0.021) was observed between time points. However, none of the patients presented clinically significant nephropathy.ConclusionsAssessment using serum creatinine and cystatin C concentrations showed changes in renal function among patients with cancer undergoing contrast-enhanced CT examination in this study. No significant renal damage related to the use of low-osmolarity iodinated contrast medium of the type and dosage employed in this study was observed. This contrast medium is thus safe for use in patients with cancer.     

Mass Isolation of Muscle Lineage Blastomeres from Ascidian Embryos

The aim of this investigation was to establish an experimental system for studying the causal relationship between DNA replication and tissue-specific enzyme development in ascidian embryos. Blastomeres were dissociated from 44∽64-ceIl Halocynthia roretzi embryos and fractionated by centrifugation through a discontinuous Percoll density gradient. When cells harvested from the fraction at the bottom of the tube were division-arrested with cytochalasin B (an inhibitor of cytokinesis) soon after their isolation, more than 70% of them developed histochemically-detectable muscle-specific acetylcholinesterase (AChE) activity, suggesting that they were almost all blastomeres of muscle lineage. When these cells were arrested with aphidicolin (an inhibitor of DNA replication) and cytochalasin B immediately after their isolation, however, none of them showed AChE activity. When they were allowed to divide once and then arrested with the inhibitors, nearly 40 % of them developed AChE activity, and when they were allowed to divide twice before arrest, about 70% of them showed AChE activity.     

Cystatin C Is Not Causally Related to Coronary Artery Disease

Background

Strong and independent associations between plasma concentration of cystatin C and risk of cardiovascular disease (CVD) suggests causal involvement of cystatin C.

Aim

The aim of our study was to assess whether there is a causal relationship between plasma concentration of cystatin C and risk of coronary artery disease (CAD) using a Mendelian Randomization approach.

Methods

We estimated the strength of association of plasma cystatin C on CAD risk and the strength of association of the strongest GWAS derived cystatin C SNP (rs13038305) on plasma cystatin C in the population-based Malmö Diet and Cancer Study (MDC) and thereafter the association between rs13038305 and CAD in the MDC (3200 cases of CAD and 24418 controls) and CARDIOGRAM (22233 cases of CAD and 64762 controls).

Results

Each standard deviation (SD) increment of plasma cystatin C was associated with increased risk of CAD (OR = 1.20, 95% CI 1.07–1.34) after full adjustment. Each copy of the major allele of rs13038305 was associated with 0.34 SD higher plasma concentration of cystatin C (P<1 x 10^-35), resulting in a power of >98% to detect a significant relationship between rs13038305 and CAD in MDC and CARDIOGRAM pooled. The odds ratio for CAD (per copy of the major rs13038305 allele) was 1.00 (0.94–1.07); P = 0.92 in MDC, 0.99 (0.96–1.03); P = 0.84 in CARDIOGRAM and 1.00 (0.97–1.03); P = 0.83 in MDC and CARDIOGRAM pooled.

Conclusion

Genetic elevation of plasma cystatin C is not related to altered risk of CAD, suggesting that there is no causal relationship between plasma cystatin C and CAD. Rather, the association between cystatin C and CAD appears to be due to the association of eGFR and CAD.     

Reference Intervals for Serum Cystatin C and Factors Influencing Cystatin C Levels Other than Renal Function in the Elderly

Objective

The present study aimed to establish reference intervals for serum cystatin C (Scys-C) stratified by stages of chronic kidney disease, explore factors influencing Scys-C and compare the performance of Scys-C with serum creatinine (Scr) in the young and elderly.

Methods

A total of 800 participants, 516 young (<60 years) and 284 old (≥60 years) subjects were included in this study. Scys-C and Scr were assayed by the partical-enhanced immunoturbidimetry method and enzymatic method respectively. 95% reference interval was adopted to evaluate reference intervals. Influencing factors were characterized by multivariate linear regression analysis. Relationship between reference glomerular filtration rate (rGFR) and Scys-C or Scr was determined by correlation coefficient.

Results

Reference intervals for Scys-C were calculated to be 0.71–1.38 mg/L, 0.83–1.67 mg/L, 1.02–2.61 mg/L, 1.32–4.48 mg/L, 1.95–6.11 mg/L in the aged in CKD G1, G2, G3a, G3b and G4-5 stages, respectively. Body mass index(BMI), nephritis, kidney neoplasm and hypertension were demonstrated as factors affecting Scys-C in the elderly while gender, nephritis and kidney neoplasm were clarified as influencing factors in the young group. Scr levels were affected by more factors, such as body surface area and hematological disease. Correlation coefficient between rGFR and Scys-C or Scr showed that serum Scys-C was superior to Scr, especially in the subjects with mildly decreased renal function (−0.593 vs. −0.520).

Conclusions

Factors other than renal function influenced Scys-C when applying to evaluate glomerular filtration rate (GFR), such as BMI, nephritis, kidney neoplasm and hypertension, and Scys-C had higher correlation with GFR than Scr in the elderly.     

抗胱抑素C鸡卵黄IgY抗体的制备及鉴定

目的:制备高效价、高特异性的抗人胱抑素 C 鸡卵黄 IgY 抗体,并对其基本特性进行分析和鉴定.方法:以人胱抑素 C 为抗免疫产蛋的罗曼鸡,采用水稀释-盐析法提取及纯化 IgY 抗体,采用蛋白质定量、SDS-PAGE、West?ern 印迹和 ELISA 法对 IgY 抗体进行分析和鉴定.结果:免疫后14 d 即可从鸡冠血中检测出抗胱抑素 C 的特异性抗体,抗体效价在28 d 达最高峰(1∶32000),并可维持2个月以上;收集高效价时的免疫鸡蛋,制备鸡卵黄抗体 IgY;还性 SDS-PAGE 显示抗体 IgY 为相对分子质量分别为65×103和21×103的2条带,抗体纯度可达92%,得率为每个鸡蛋36.5 mg,抗体检出敏感度为15.63 ng/mL;Western 印迹证明该抗体具有高度特异性.结论:制备了抗胱抑素 C 的高效价、高特异性 IgY 抗体.     

重组人胱抑素C的原核表达及鉴定

目的构建重组人胱抑素C（cystatinC,CysC）的原核高效表达质粒,诱导表达并纯化获得CysC重组蛋白。方法根据大肠埃希菌编码蛋白的特性设计CysC编码基因序列,人工合成目的基因克隆至pET-22b（＋）表达载体中,测序及酶切鉴定正确后诱导其在大肠埃希菌BL21中表达,所获得的包涵体蛋白经亲和层析纯化后采用SDS—PAGE及Western印迹鉴定。结果酶切结果证实构建的表达质粒结构正确;测序结果显示克隆的基因序列所编码的蛋白与GenBank中的CysC氨基酸序列相符;SDS-PAGE及Western印迹结果证实获得的重组CysC融合蛋白分子量约为16kD,经NP亲和层析纯化获得纯度大于90％的目的蛋白。结论建立了重组人CysC的原核高效表达系统并获得了CysC重组蛋白。     

Effects of Bed-Rest on Urea and Creatinine: Correlation with Changes in Fat-Free Mass

Background

Bed-rest experiments are designed for investigation on catabolic effects of hypokinetic conditions and/or for microgravity simulation in on-ground aerospace research. Bed-rest effects include a reduction in fat-free mass and muscle mass. Urea and creatinine are catabolites of endogenous protein and of muscular energetic metabolism which are excreted mainly by the kidney. The study investigated on urea, creatinine, and kidney function during bed-rest.

Methods

Twenty healthy young men underwent a 7-day adaptation period (day-6 to day-0) and a 35-day bed-rest experiment (day1 to day35) during normocaloric diet. Urine were collected from day-3 to day0 (baseline) and from day1 to day35. Blood samples and anthropometrical data were collected at day0 (baseline) and bed-rest days 7, 14, 21, 28, and 35.

Results

Bed-rest reduced plasma volume, weight, fat-free mass, and muscle mass (P<0.001). During bed-rest there was a transient increase in plasma and urinary urea, a decrease in plasma creatinine, and no change in urinary creatinine. The overall integral of changes from day0 to day35 was on average +101.7 mg/dL for plasma urea (95%CI = +43.4/+159.9), +82.2 g/24 h for urinary urea (95%CI = +55.8/+108.7), −2.5 mg/dL for plasma creatinine (95%CI = −3.1/−1.9). Bed-rest reduced plasma cistatyn C also, which was used as mass-independent marker of glomerular filtration rate (−13.1%, P<0.05). Correlations with final reduction in fat-free mass and muscle mass were significant for the overall integral of changes in urinary urea from day0 to day35 (R = 0.706, P<0.001) and for early changes in urinary urea and plasma urea from day0 to day7 (R = 0.566, P = 0.009 and R = 0.715, P<0.001, respectively).

Conclusions

Study results shows that urea is a marker of catabolic conditions secondary to hypokinetic conditions.     

Dexamethasone and BCAA Failed to Modulate Muscle Mass and mTOR Signaling in GH-Deficient Rats

Branched-chain amino acids (BCAAs) and IGF-I, the secretion of which is stimulated by growth hormone (GH), prevent muscle atrophy. mTOR plays a pivotal role in the protective actions of BCAA and IGF-1. The pathway by which BCAA activates mTOR is different from that of IGF-1, which suggests that BCAA and GH work independently. We tried to examine whether BCAA exerts a protective effect against dexamethasone (Dex)-induced muscle atrophy independently of GH using GH-deficient spontaneous dwarf rats (SDRs). Unexpectedly, Dex did not induce muscle atrophy assessed by the measurement of cross-sectional area (CSA) of the muscle fibers and did not increase atrogin-1, MuRF1 and REDD1 expressions, which are activated during protein degradation. Glucocorticoid (GR) mRNA levels were higher in SDRs compared to GH-treated SDRs, indicating that the low expression of GR is not the reason of the defect of Dex’s action in SDRs. BCAA did not stimulate the phosphorylation of p70S6K or 4E-BP1, which stimulate protein synthesis. BCAA did not decrease the mRNA level of atrogin-1 or MuRF1. These findings suggested that Dex failed to modulate muscle mass and that BCAA was unable to activate mTOR in SDRs because these phosphorylations of p70S6K and 4E-BP1 and the reductions of these mRNAs are regulated by mTOR. In contrast, after GH supplementation, these responses to Dex were normalized and muscle fiber CSA was decreased by Dex. BCAA prevented the Dex-induced decrease in CSA. BCAA increased the phosphorylation of p70S6K and decreased the Dex-induced elevations of atrogin-1 and Bnip3 mRNAs. However, the amount of mTORC1 components including mTOR was not decreased in the SDRs compared to the normal rats. These findings suggest that GH increases mTORC1 activity but not its content to recover the action of BCAA in SDRs and that GH is required for actions of Dex and BCAA in muscles.     

青阳参的一个新C21甾体苷

从萝藦科药用植物青阳参(CynanchumotophyllumSchneid)的乙酸乙酯提取物的酸水解液中,分离得到一个新的C21甾体苷类化合物,通过现代波谱技术,确定其结构为去乙酰藦萝苷元3-O-β-D-夹竹桃吡喃糖基-(1→4)-α-D-夹竹桃吡喃糖苷。     

Serum Creatinine Modifies Associations between Body Mass Index and Mortality and Morbidity in Prevalent Hemodialysis Patients

Background

High body mass index (BMI) is paradoxically associated with better outcomes in hemodialysis (HD) patients. This study aimed to examine whether serum creatinine (Cr), a marker of muscle mass, could modify the association between BMI, and mortality and morbidity in prevalent HD patients.

Methods

A retrospective study was conducted using a nationwide database from the registry of the Japanese Society for Dialysis Therapy. A total of 119,099 patients were selected (age: 65±12 years; median time on HD: 5.6 years; male: 62%), and we examined the association of basal BMI with mortality and morbidity after a 1-year period. Patients were stratified either by BMI into 4 groups or by serum Cr levels into 3 tertiles. Odds ratio (OR) [95% confidence interval] was calculated by multivariate logistic regression analysis.

Results

Higher BMI did not predict a higher 1-year total mortality. However, when we stratified the patients by serum Cr levels, the risk of cardiac death became significantly higher in obese patients with the lowest Cr levels, in both males (OR 2.82 [1.51–5.27], p<0.01) and females (OR 2.00 [1.03–3.90], p<0.05). The risk of new cerebral infarction was also higher in obese male patients within the lowest Cr tertile. In contrast, there was a significantly lower risk of cardiac, cerebrovascular, and infection-related death in non-obese patients with higher levels of Cr. Higher serum Cr was also related to a lower risk of cardiovascular events and hip fracture in non-obese HD patients.

Conclusions

The obesity paradox was found to be present in HD patients only when obesity was defined by BMI. Decreased serum Cr levels were found to be positively associated with clinical poor outcomes in all BMI groups. Thus, irrespective of BMI, the evaluation of serum Cr levels is important to predict mortality and morbidity in patients receiving regular HD.     

徐长卿中的一个新的C21甾体配糖体

从传统中药徐长卿（Cynanchum paniculatum Ktag)根茎的乙酸乙酯提取物中分离得到1个新的C21甾体配糖体,经1D,2D-NMR波谱分析,确定其结构为新白薇甙元C3-O-β-D-夹竹桃吡喃糖甙（1）。     

A Dietary Supplementation with Leucine and Antioxidants Is Capable to Accelerate Muscle Mass Recovery after Immobilization in Adult Rats

Prolonged inactivity induces muscle loss due to an activation of proteolysis and decreased protein synthesis; the latter is also involved in the recovery of muscle mass. The aim of the present work was to explore the evolution of muscle mass and protein metabolism during immobilization and recovery and assess the effect of a nutritional strategy for counteracting muscle loss and facilitating recovery. Adult rats (6–8 months) were subjected to unilateral hindlimb casting for 8 days (I0–I8) and then permitted to recover for 10 to 40 days (R10–R40). They were fed a Control or Experimental diet supplemented with antioxidants/polyphenols (AOX) (I0 to I8), AOX and leucine (AOX + LEU) (I8 to R15) and LEU alone (R15 to R40). Muscle mass, absolute protein synthesis rate and proteasome activities were measured in gastrocnemius muscle in casted and non-casted legs in post prandial (PP) and post absorptive (PA) states at each time point. Immobilized gastrocnemius protein content was similarly reduced (-37%) in both diets compared to the non-casted leg. Muscle mass recovery was accelerated by the AOX and LEU supplementation (+6% AOX+LEU vs. Control, P<0.05 at R40) due to a higher protein synthesis both in PA and PP states (+23% and 31% respectively, Experimental vs. Control diets, P<0.05, R40) without difference in trypsin- and chymotrypsin-like activities between diets. Thus, this nutritional supplementation accelerated the recovery of muscle mass via a stimulation of protein synthesis throughout the entire day (in the PP and PA states) and could be a promising strategy to be tested during recovery from bed rest in humans.