Transglutaminase 2 Has Metabolic and Vascular Regulatory Functions Revealed by In Vivo Activation of Alpha1-Adrenergic Receptor.

The multifunctional tissue transglutaminase has been demonstrated to act as α1-adrenergic receptor-coupled G protein with GTPase activity in several cell types. To explore further the pathophysiological significance of this function we investigated the in vivo effects of the α1-adrenergic receptor agonist phenylephrine comparing responses in wild type and TG2-/- mice. Injection of phenylephrine, but not a beta3-adrenergic agonist (CL-316,243), resulted in the long-term decline of the respiratory exchange ratio and lower lactate concentration in TG2-/- mice indicating they preferred to utilize fatty acids instead of glucose as fuels. Measurement of tail blood pressure revealed that the vasoconstrictive effect of phenylephrine was milder in TG2-/- mice leading to lower levels of lactate dehydrogenase (LDH) isoenzymes in blood. LDH isoenzyme patterns indicated more damage in lung, liver, kidney, skeletal, and cardiac muscle of wild type mice; the latter was confirmed by a higher level of heart-specific CK-MB. Our data suggest that TG2 as an α1-adrenergic receptor-coupled G protein has important regulatory functions in alpha1-adrenergic receptor-mediated metabolic processes and vascular functions.

[Inborn error of cholesterol biosynthesis: Smith-Lemli-Opitz syndrome]. / A koleszterin-bioszintézis veleszületett zavara: a Smith-Lemli-Opitz-szindróma.

Smith-Lemli-Opitz syndrome is an autosomal recessive mental retardation and multiple malformation syndrome caused by deficiency of the 7-dehydrocholesterol reductase, the enzyme catalyzing the last step in cholesterol biosynthesis. The authors summarize the pathophysiology, epidemiology, clinical picture, diagnostics and therapy of the disease based on a review of the international literature. Since 2004, fourteen patients have been diagnosed with Smith-Lemli-Opitz syndrome in Hungary, which suggests an underdiagnosis of the disease based upon estimated incidence data. Due to deficiency of the 7-dehydrocholesterol reductase, serum cholesterol concentration is low and 7-dehydrocholesterol concentration is elevated in blood and tissues; the latter being highly specific for the syndrome. Detection of disease-causing mutations makes the prenatal diagnosis possible. The clinical spectrum is wide, the most common symptom is syndactyly of the second and third toes. Standard therapy is cholesterol supplementation. Recent publications suggest that oxidative compounds of 7-dehydrocholesterol may play a role in the pathophysiology of the disease as well.

[Pneumatic tube system for transport of laboratory samples: preanalytical aspects]. / Preanalitikai szempontok pneumatikus csopostával szállított laboratóriumi minták esetén.

INTRODUCTION: A considerable proportion of laboratory errors occurs in the preanalytical phase. AIM: The aims of the authors were to study preanalytical errors in routine and emergency laboratory diagnostics in a regional clinical laboratory and evaluate the effect of the pneumatic tube system on turnaround time and laboratory results. METHOD: The ratio of preanalytical errors and reasons of test rejection were analysed. In addition, the effects of pneumatic tube and manual transport on the occurrence of hemolysis and platelet activation were compared. RESULTS: Using the pneumatic tube transport system, preanalytical error was below 1%. The main causes of test rejection were haemolysis in case of serum samples, and clot formation and citrate excess in anticoagulated samples. The pneumatic tube transport resulted in significantly faster sample transport, more equalized sample arrival and processing, hence the turnaround time became shorter both for routine and emergency tests. CONCLUSIONS: Autovalidation and proper control of preanalytical errors are essential for rapid and reliable laboratory service supported by the pneumatic tube system for sample transport.

[Interpretation of highly sensitive troponin assays: acute or chronic myocardial damage?]. / Nagy érzékenységu troponintesztek értékelése: akut vagy krónikus szívizom-károsodás?

UNLABELLED: Troponin is the first choice in the diagnosis of acute myocardial infarction. Correct interpretation is challenging, because high sensitive troponin tests used today detect even the smallest cardiac damage. METHODS: High sensitive troponin T (Roche) and troponin I (Mitsubishi Pathfast) and creatine-kinase activity were measured in 20 patients, each having two samples with the time lapse 3-9 hours. RESULTS: In the group without acute myocardial infarction (n = 10) no significant increase in creatine-kinase and creatine-kinase-MB levels were seen, and the mild raise of troponins was due to other cardiovascular problems (atrial fibrillation, paroxysmal supraventricular tachycardia). With acute myocardial infarction (n = 10) a dramatic increase of troponin levels was found in the second samples, and also an increase of creatine-kinase and creatine-kinase-MB activity. According to Fischer-probe a twofold or higher increase of troponin implies 19-times higher risk of acute myocardial infarction in the case of troponin T and 8-times odds ratio at troponin I. CONCLUSIONS: The patient's accompanying diseases should always be considered. If the troponin level is elevated, the measurement should be repeated within 3-6 hours. When troponin shows at least a twofold increase and the patient has chest pain or positive ECG, AMI is likely, and the patient needs special medical care. Although the first troponin level might be elevated if accompanying diseases cause chronic cardiac damage, it can be differentiated by a second troponin measurement.

[Biochemical alterations in patients with Down syndrome]. / Biokémiai eltérések Down-szindromás betegekben.

UNLABELLED: Down syndrome is a chromosome abnormality with specific clinical symptoms and mental retardation caused by trisomy of chromosome 21. The basic genetic change cannot be cured, the control of the associated symptoms, however, may improve the patients' quality of life. AIMS: Authors studied the possible correlations between the Down-specific genes and the related biochemical changes. Expression of superoxide dismutase, cystathionine-beta-synthase and S100 protein was investigated. Further aim of the study was to determine the total serum antioxidant capacity (transferrin, ferritin, total protein, albumin and bilirubin) along with the extracellular antioxidants as well as concentrations of homocysteine, folic acid, and vitamin B 12 . To assess the vascular damage, the activity of NAG and S100B level was measured. METHODS: Standard laboratory methods were used to determine the antioxidant capacity (Stocks, 1974), homocysteine (HPLC), folic acid (capture, IMX-Abbott), vitamin B 12 (MEIA, IMX-Abbott), S100 B protein (chemiluminescence sandwich immunoassay) levels, and N-acetyl-beta-D-glucosaminidase (spectrophotometry). RESULTS: Plasma homocysteine value proved to be lower in 7 of the 30 and higher in 6 of the 30 patients studied than the reference range. Plasma homocysteine was found 95 +/- 21% of the reference value. Relative value of plasma folic acid - expressed in percent of the normal value - was 85 +/- 51%, and that of B 12 was 78 +/- 30%. Deficiency of folic acid was detected in 2 of the 30, decreased level of B 12 in 2 of the 30 patients enrolled. No difference was found in antioxidant activity values between Down syndrome patients and healthy controls, however, neither of them reached the adult reference range. S100 protein concentration of 4-8 times higher values (average value: 0.68 +/- 0.27 microg/l) than upper limit of the reference range was observed (> 1 year: > 0.15 microg/l). Mean value of serum N-acetyl-beta-D-glucosaminidase remained within the reference range (10-30 U/l). No statistically significant correlation between the antioxidant activity and N-acetyl-beta-D-glucosaminidase values could be observed. CONCLUSION: The lower homocysteine, folic acid and B 12 values may be considered as the consequence of an increased cystathionine-beta-synthase activity ("atheroma free model"). There was no significant alteration in antioxidant activity level. It can be supposed that the hydrogene peroxide produced due to increased expression of superoxide dismutase is metabolized by the induced glutathione-peroxidase and catalase keeping by this the balance of the antioxidant system. This hypothesis is supported by the normal N-acetyl-beta-D-glucosaminidase values not indicating any vascular damage. The high S100 values, however, reflect certain brain damage which shows a progress with the age. Based on these experiences, regular control of these parameters is recommended. Furthermore authors think that folic acid supplementation is indicated in order to improve the patients' learning capacity, inhibit the development of Alzheimer symptoms and improve the quality of life.

[Challenge and limitations in determination of serum creatinine]. / A szérumkreatinin-meghatározás kihívásai és korlátai.

Since 2006 clinical guidelines have recommended that the estimated glomerular filtration rate should be calculated from serum creatinine for the early detection of chronic kidney disease. These brought into the limelight the limitations of the Jaffe method and for comparability of test results the different routine creatinine methods need to be harmonized. The disadvantage of the kinetic Jaffe creatinine determination is its low specificity. This was improved by the enzymatic, compensated-Jaffe and high resolution liquid chromatographic assays introduced in the last decade. Creatinine values determined by the new methods are more accurate, but give lower creatinine values, therefore the glomerular filtration rate would be overestimated, if the new creatinine results were applied in the previous formulae (4-variables Modification of Diet in Renal Disease-186, Cockcroft-Gault, Quadratic). Because of the new creatinine methods estimation of the glomerular filtration rate and classification in chronic kidney disease staging became uncertain. Therefore the 4-variables Modification of Diet in Renal Disease-186 formula has been adjusted in 2006 and for the new creatinine methods (traceable to the isotope-dilution mass spectrometry) only the new Modification of Diet in Renal Disease-175 formula is advised. Authors compare the diagnostic value and limitations of the creatinine methods.

[The epidemic of chronic kidney disease requires the estimation of glomerular filtration rate]. / Az idült vesebetegség epidémiája szükségessé teszi a glomerulus filtrációs ráta számítását.

Nowadays chronic kidney disease has become a major public health problem due to the great increase in atherogenic nephropathies. In the absence of classic renal symptoms, chronic kidney disease is mostly diagnosed when renal failure is already advanced, although it can be revealed by laboratory tests in the earlier stages. When diagnosis is late, the progression to end-stage renal failure is unavoidable and renal replacement therapy is needed. Even early-moderate renal failure significantly increases the risks for atherosclerosis, thereby leading to the deaths of patients from cardiovascular disease before initiation of dialysis. Therefore screening for asymptomatic chronic kidney disease is urgently needed. Estimated glomerular filtration rate has the greatest importance in the screening and in the timely intervention to slow down the progression of renal failure and cardiovascular disease. In 2005, the Hungarian Society of Nephrologists and the Hungarian Society of Laboratory Medicine suggested the automatic estimation and reporting of glomerular filtration rate, each time serum creatinine measurements were made. This practice is used more frequently by laboratories in Hungary. This article aims to help facilitate the utilization and evaluation of estimated glomerular filtration rate.

Anthracycline antibiotics induce acute renal tubular toxicity in children with cancer.

Experimental evidence suggests that anthracyclines, widely used in cancer chemotherapy, may impair kidney function. We assessed kidney function by serum creatinine, urinary N-acetyl-beta-D-glucosaminidase activity indices (NAGi) and microalbuminuria (MA) in 160 serum and urine samples obtained from 66 children with cancer. The effect of dexrazoxane was analyzed in 6 children on dexrazoxane supportive therapy in conjunction with daunorubicin (DNR) treatment, as compared with 6 children not receiving this agent. NAGi was significantly (p<0.05) elevated after treatment by DNR, doxorubicin, epirubicin (EPI) and idarubicin (IDA). MA proved to be a less sensitive indicator of kidney damage than NAGi. DNR resulted in a progressive deterioration of proximal tubular function as determined by linear regression analysis. The mean NAGi in the dexrazoxanetreated group was significantly (p<0.005) lower than in children not receiving dexrazoxane prior to DNR treatment. In conclusion, our study demonstrated that DNR, EPI and IDA induced an acute renal tubular damage similar to known tubulotoxic agents as cisplatin, carboplatin, cyclophosphamide and ifosfamide. The damage was clinically mild and only a minor proportion of patients can be expected to develop long-lasting tubulopathy with negative impact on the quality of life.

["Turnaround time": a new parameter for the characterization of the overall efficacy of laboratory diagnostic processes]. / "Turnaround time": a laboratóriumi eredménykiadás hatékonyságának új paramétere.

INTRODUCTION: The authors developed a special computer-aided routine in their laboratory for the calculation of "turnaround time" which parameter is suitable for the characterization of the overall efficacy of laboratory diagnostic processes. The turnaround time is defined as the interval between the arrival time of a sample in the laboratory and the time of clinical validation. It characterizes the efficacy of the result generation process very well, and therefore, is considered as an important parameter of laboratory quality control. METHODS: In their present study the authors analyzed the data of the urgent (stat), routine and special laboratory tests of 6 months and presented the median, 5- and 95-percentile values of turnaround time. Beside this, they calculated the rate of "outliers": the number of tests having a longer turnaround time value, than the defined maximal turnaround time (stat 1 hour, routine 4 hours, special 2-14 days). RESULTS: The median turnaround time values were 9-70 minutes for the stat tests and 33-190 minutes for the routine analytes. In case of special tests, the results were much more heterogeneous, in general non-automated hemostasis and immunochemistry assays, with low sample numbers had longer turnaround time values and higher number of outliers. Longitudinal analysis of routine tests showed clearly that turnaround time values became shorter in every unit during the 1st 6 months of 2006. Clinical validation is an important component altering turnaround time that can be shortened substantially with the installation of an autovalidation program. Based on the data of the authors the median turnaround time values of routine assays were shortened by 1-2 hours after introduction of autovalidation. The applied program for turnaround time analysis is suitable for evaluation of sample transfer times, too, that was presented by comparison of two "emergency units" having different sample transfer facilities. CONCLUSIONS: The described turnaround time analysis is part of the general routine processes in laboratories of the developed countries but is the first such trial in Hungary.