Aimo Harmoinen

Elevated Serum C-Reactive Protein Levels and Early Arterial Changes in Healthy Children

Objective—Elevated serum concentration of C-reactive protein (CRP) predicts cardiovascular events in adults. Because atherosclerosis begins in childhood, we undertook a study to determine whether changes in brachial artery endothelial function and the thickness of the carotid intima-media complex, 2 markers of early atherosclerosis, are related to CRP levels in healthy children. Methods and Results—Brachial artery flow-mediated dilatation (FMD) and carotid artery intima-media thickness (IMT) were measured with ultrasound in 79 children (aged 10.5±1.1 years). Compared with the children with CRP levels under the detection limit (<0.1 mg/L, n=40, group 1), the children with higher CRP (0.1 mg/L≤CRP≤0.7 mg/L, n=20, group 2; CRP >0.7 mg/L, n=19, group 3) had lower FMD (9.0±4.4% versus 7.8±3.3% versus 6.5±2.6%, respectively;P =0.015 for trend) and greater carotid IMT (0.45±0.03 versus 0.46±0.04 versus 0.49±0.06 mm, respectively, P =0.002 for trend). CRP level remained a statistically significant independent predictor for brachial FMD and carotid IMT in multivariate analyses. Conclusions—These data suggest that CRP affects the arteries of healthy children by disturbing endothelial function and promoting intima-media thickening. The findings support the hypothesis that CRP plays a role in the pathogenesis of early atherosclerosis.

Weight Reduction With Very-Low-Caloric Diet and Endothelial Function in Overweight Adults: Role of Plasma Glucose

Objective—Obesity is associated with endothelial dysfunction that may contribute to the development of atherosclerosis. We studied whether weight reduction improves endothelial function in overweight individuals. Methods and Results—Flow-mediated endothelium-dependent vasodilation of the brachial artery was measured in 67 adults (age: 46±7 years, body mass index: 35.2±5.4 kg/m2) before and after a 6-week weight reduction program induced by very-low-calorie diet (daily energy: 580 kcal/2.3 MJ). Caloric restriction reduced body weight from 101±18 to 90±17 kg. Flow-mediated vasodilation increased from 5.5%±3.7 to 8.8%±3.7% (P <0.0001). Nitrate-mediated vasodilation was not significantly affected. The improvement in flow-mediated dilation was associated with the reduction in plasma glucose concentration (P =0.0003). This relationship was independent of changes in weight, serum lipids, oxidized LDL, C-reactive protein, adiponectin, blood pressure, and insulin. Conclusions—Weight reduction with very-low-calorie diet improves flow-mediated vasodilation in obese individuals. This improvement is related to the reduction in plasma glucose concentration. These observations suggest that changes in glucose metabolism may determine endothelial vasodilatory function in obesity.

Reference intervals for cystatin C in pre- and full-term infants and children.

Abstract Cystatin C is a non-glycated, 13-kDa basic protein produced by all nucleated cells. Recent studies have indicated that the plasma concentration of cystatin C is a better marker for glomerular filtration rate (GFR) than plasma creatinine, which is most commonly used for this purpose. We established reference values for plasma cystatin C in pre- or full-term infants and children. For comparison we also measured the creatinine concentration in the same samples. Cystatin C was measured by a commercially available immunoturbidimetric method with a Hitachi 704 analyzer in sera obtained from 58 pre-term infants, 50 full-term infants and 299 older children (132 girls, 167 boys, median age 4.17 years, range 8 days to 16 years). No sex differences were found. The pre-term infants had higher cystatin C concentrations (mean 1.88 mg/l, SD 0.36 mg/l) than the full-term (mean 1.70 mg/l, SD 0.26 mg/l, P=0.0145). The reference interval for pre-term infants calculated non-parametrically was 1.34–2.57 mg/l and for full-term infants 1.36–2.23 mg/l. The cystatin C concentration decreased rapidly after birth, and above 3 years of age did not depend on age. The reference interval for children 3–16 years of age calculated non-parametrically was 0.51–1.31 mg/l. Younger children (<1 year: 0.75–1.87 mg/l; 1–3 years: 0.68 –1.60 mg/l) had slightly, but significantly, higher plasma cystatin C levels.

Cystatin C as a marker for glomerular filtration rate in pediatric patients

Abstract Cystatin C is a non-glycated 13-kilodalton basic protein produced by all nucleated cells. The low molecular mass and the basic nature of cystatin C, in combination with its stable production rate, suggest that the glomerular filtration rate (GFR) is the major determinant of cystatin C concentration in the peripheral circulation. Recently published studies have shown that cystatin C correlates more strongly than creatinine with GFR measured using the 51Cr-EDTA clearance. The aim of this study was to evaluate serum cystatin C as a marker for GFR in children. GFR was determined on medical indications using the 51Cr-EDTA technique in pediatric patients (2–16 years) in our renal unit. Simultaneously their cystatin C and creatinine concentrations were also measured. Of our 52 patients, 19 had a reduced renal function (<GFR 89 ml/min per 1.73 m2) based on the 51Cr-EDTA clearance. The correlation of cystatin C with the isotopic measurement of GFR tended to be stronger (r=0.89, P=0.073) than that of creatinine (r=0.80). Receiver operating characteristic analysis showed that the diagnostic accuracy of cystatin C was better (P=0.037) than that of creatinine in discriminating between subjects with normal renal function and those with reduced GFR. This study demonstrates that serum cystatin C has an increased diagnostic accuracy for reduced GFR when compared with serum creatinine. Hence, cystatin C seems to be an attractive alternative for the estimation of GFR in children.

Pretreatment with antioxidants and allopurinol diminishes cardiac onset events in coronary artery bypass grafting

Oxygen-derived free radicals constitute one part of the etiologic factors for cardiac onset harmful events. Allopurinol is able to reduce the generation of free radicals. Vitamins E and C scavenge radicals after their formation. Eighty-one patients with coronary artery disease were randomized into four study groups: Group 1 (n = 20) patients had stable disease and received oral vitamin E for 4 weeks, and vitamin C and allopurinol 2 days before and 1 day after coronary artery bypass grafting. Group 2 (n = 25) consisted of their controls. Group 3 patients (n = 17) had more unstable disease and received the same medications as group 1, except that vitamin E was given only 2 days before the operation. Group 4 (n = 19) was their controls. Groups 1 and 3 had fewer ischemic electrocardiographic events and required less dopamine perioperatively than corresponding control groups 2 and 4. Group 3 had fewer perioperative infarctions and less creatine kinase-MB release than the respective controls (group 4). Plasma levels of vitamins E and C, urate, and total free radical trapping ability were considered to support the theory about the role of free radicals in reperfusion injury. Especially the unstable patients, but also patients with stable coronary artery disease requiring coronary artery bypass grafting benefit from perioperative allopurinol and vitamin E and C treatment.

Diagnostic Accuracies of Plasma Creatinine, Cystatin C, and Glomerular Filtration Rate Calculated by the Cockcroft–Gault and Levey (MDRD) Formulas

Estimation of the glomerular filtration rate (GFR) is the most widely used test of renal function, reflecting the relative mass of functional renal tissue and thus the number of functioning nephrons. Methods based on measurement of exogenous substances such as inulin, 51Cr-EDTA, 99mTc-diethylenetriaminepentaacetic acid, and iohexol are accurate but too complex and laborious for routine clinical use; thus, measurement of endogenous blood substances is common practice. Plasma or serum creatinine and its renal clearance are the approaches most commonly used despite their acknowledged unreliability. Cystatin C, a small basic protein, has been proposed as a better marker than creatinine. Recently, the value of cystatin C was thoroughly reviewed in this Journal (1), and according to this review and a new metaanalysis (2), most studies have concluded that cystatin C is superior to plasma creatinine, whereas several authors have concluded that cystatin C provides no advantage. One purpose of the present study was to clarify possible reasons for the earlier, partly conflicting results. A recently published guideline from the National Kidney Foundation (3) recommended that GFR be estimated from prediction equations taking into account the serum creatinine concentration and some or all of the following variables: age, gender, race, and body size. We therefore also compared cystatin C with GFRs calculated by the Cockcroft–Gault (4) and the MDRD(5) formulas. We studied 112 patients (55 men and 57 women) for whom 51Cr-EDTA clearance had been requested. The mean age of the patients was 57.0 years (range, 17–89 years). Body mass index (BMI) was 15.2–42.4 kg/m2, and 51 …

Acute Phase Reaction, Infarct Size and In-Hospital Morbidity in Myocardial Infarction Patients Treated With Streptokinase or Recombinant Tissue Type Plasminogen Activator

We examined the acute phase reaction in myocardial infarction after thrombolytic treatment by streptokinase or tissue plasminogen activator. The magnitude of the acute phase reaction as determined by measurements of serum C-reactive protein and amyloid-A protein did not correlate with infarct size (determined by serial measurements of creatine kinase-MB) in this patient population. On the other hand, the development of acute cardiac failure was more closely associated with the magnitude of the acute phase reaction than with infarct size. The peak serum values of C-reactive protein in patients with and without acute cardiac failure were 128 mg/l (95% confidence intervals 85-170) and 60 mg/l (30-89); P less than 0.01 and concentration time integrals 578 mg/l x days (368-787) and 205 mg/l x days (62-350); P less than 0.01. The corresponding creatine kinase-MB values were 310 U/l (191-429) and 207 U/l (125-289) not significant; and 319 U/l x days (201-437) and 204 U/l x days (124-286) not significant; respectively. Patients requiring medication for cardiac failure on discharge from hospital had higher C-reactive protein and serum amyloid A protein values than those who did not, although the difference did not quite reach statistical significance. The infarct sizes were similar whether the patients needed medication for cardiac failure at discharge or not. Subjectively felt morbidity due to myocardial infarction was linearly associated with serum C-reactive protein peak values (P less than 0.05) and concentration time integrals (P less than 0.05), but not with infarct size. We conclude that thrombolytic treatment of myocardial infarction may reduce hospital inpatient morbidity independently of the limitation of infarct size. This diminished morbidity seems to be associated with modest or low acute phase reaction.

Focusing on the clinical impact of standardization of creatinine measurements: a report by the EFCC Working Group on Creatinine Standardization

Abstract The recent campaign for standardization of creatinine measurements has been promoted to allow the widespread use of formulas for estimating the glomerular filtration rate (GFR). However, studies on trueness verification and measurement interferences still show disappointing interassay variation of serum creatinine results. Creatinine recalibration has major clinical consequences. In particular, in pediatrics where reference ranges for serum and plasma creatinine are low, calculation of the GFR is problematic when based on alkaline picrate methods because of method non-specificity and the lack of appropriate GFR estimating formulas. Therefore, enzymatic creatinine assays are preferred. In the near future, cystatin C might offer an interesting alternative for GFR estimation. For the calculation of drug doses, the Modification of Diet in Renal Disease study formula generally offers reliable data. However, attention has to be paid to the elderly. Also, the calculation of the Model for End-Stage Liver Disease score, which is used to prioritize patients for liver transplantation, may significantly be influenced by recalibration of creatinine assays. Creatinine restandardization may also affect the current guidelines for referral of chronic kidney disease patients to nephrologists.

Trueness verification of actual creatinine assays in the European market demonstrates a disappointing variability that needs substantial improvement. An international study in the framework of the EC4 creatinine standardization working group

Abstract Background: The European In Vitro Diagnostics (IVD) directive requires traceability to reference methods and materials of analytes. It is a task of the profession to verify the trueness of results and IVD compatibility. Methods: The results of a trueness verification study by the European Communities Confederation of Clinical Chemistry (EC4) working group on creatinine standardization are described, in which 189 European laboratories analyzed serum creatinine in a commutable serum-based material, using analytical systems from seven companies. Values were targeted using isotope dilution gas chromatography/mass spectrometry. Results were tested on their compliance to a set of three criteria: trueness, i.e., no significant bias relative to the target value, between-laboratory variation and within-laboratory variation relative to the maximum allowable error. Results: For the lower and intermediate level, values differed significantly from the target value in the Jaffe and the dry chemistry methods. At the high level, dry chemistry yielded higher results. Between-laboratory coefficients of variation ranged from 4.37% to 8.74%. Total error budget was mainly consumed by the bias. Non-compensated Jaffe methods largely exceeded the total error budget. Best results were obtained for the enzymatic method. The dry chemistry method consumed a large part of its error budget due to calibration bias. Conclusions: Despite the European IVD directive and the growing needs for creatinine standardization, an unacceptable inter-laboratory variation was observed, which was mainly due to calibration differences. The calibration variation has major clinical consequences, in particular in pediatrics, where reference ranges for serum and plasma creatinine are low, and in the estimation of glomerular filtration rate. Clin Chem Lab Med 2008;46:1319–25.

A new biodegradable stent for the pancreaticojejunal anastomosis after pancreaticoduodenal resection: in vitro examination and pilot experiences in humans.

We sought to develop a biodegradable pancreatic stent that could be easily placed at operation into the human pancreatic duct and the degradation of which could be easily followed up. Spiral-shaped, gamma-sterilized stents were manufactured of 0.4-mm polylactide wire in which there was added 23 weight-% barium sulfate. The biodegradability of the stents was studied in vitro at two different pH values, the first resembling that of pancreatic juice and the other that of bile. The effects of enzymoactivity in the test solution and the composition of the stents (with or without barium addition) also were tested. These kinds of stents have been experimented with in two pilot patients. Degradation of the stents occurred from 24 to 52 weeks of incubation. Alkaline milieu together with the presence of pancreatic enzyme made the stents degrade twice as fast as when either alkaline milieu or enzyme was present. In the milieu resembling pancreatic juice, barium sulfate had no effect on the degradation time. Neither of the pilot patients had any postoperative complications. Biodegradable, x-ray–positive stents degrade faster in pancreatic than in biliary milieu. Their safety and efficacy in human pancreaticojejunal anastomoses need further study.