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  • Author: Duško Mirković x
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Recommedition for Apllication and Determination Tumor Markers of Neuroendocrine System

Preporuke Za Primenu I Određivanje Tumorskih Markera Kod Neoplazmi Neuroendokrinog Sistema

Neuroendokrini tumori vode poreklo iz neuroendokrinih ćelija, koji pod uslovima specifične stimulacije sekretuju hormone, regulišući niz različitih funkcija u organizmu. U radu je opisana grupa neuroendokrinih tumora koja se sastoji od: karcinoida endokrinih tumora pankreasa, neuroblastoma, medularnog karcinoma tiroidee i feohromocitoma. Biće diskutovani tumori koji potiču iz endokrinih žlezda, kao i oni koji vode poreklo iz takozvanog »difuznog« neuroendokrinog ćelijskog sistema gastrointestinalnog trakta. Radi se o najvećem endokrinom organu u organizmu. Oko 50 različitih neuroendokrinih ćelijskih tipova gastrointestinalnog trakta je indentifikovano. Važan dijagnostički segment u tretmanu ovih tumora, je određivanje biogenih amina i peptida, čija je aktivnost izmenjena kod pojave neoplazmi. Širok je spektar kliničkih simptoma kod pojave ove vrste tumora, a svi su posledica sposobnosti tumora da sekretuju povećane količine peptinih hormona i biogenih amina. Glavni ciljevi ovog teksta su procena važnosti ove grupe tumorskih markera, kao i predlozi za njihovo koriŠćenje u našim uslovima.

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Hyperhomocysteinemia and Smoking in Primary Antiphospholipid Syndrome

Hyperhomocysteinemia and Smoking in Primary Antiphospholipid Syndrome

The thrombotic tendency in antiphospholipid syndrome (APS) shares several pathways with atherosclerosis. Atherothrombosis (atherosclerosis superimposed with thromboses) is influenced by nonmodifiable and some modifiable risk factors (smoking, obesity, physical inactivity, alcohol abuse, hyperhomocysteinemia). Therefore, we investigated the association among clinical and serological features of patients with primary APS and potentially modifiable risk factors for the development of atherothrombosis. Also, we compared the analyzed parameters with those in control subjects. Homocysteine concentrations were detected by HPLC (high performance liquid chromatography), while antiphospholipid antibodies were detected by ELISA. Smokers had elevated levels of homocysteine (χ2 = 6.22, p < 0.05). Independently of patients' age, the association between increased levels of homocysteine and history of myocardial infarctions was found (χ2 = 4.61, p < 0.05). Hyperhomocysteinemia and smoking are the most important modifiable risk factors for atherothrombosis in primary APS.

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Comparison of three different methods for 25(oh)-vitamin d determination and vitamin d status in general population – Serbian experience / Poređenje tri različite metode za određivanje 25(oh)-vitamina D i statusa vitamina D u opštoj populaciji – srpsko iskustvo

Summary

Determination of 25-hydroxyvitamin D [25(OH)D] represents a unique challenge, considering its lipophilic na - ture. Considering the widespread prevalence of vitamin D deficiency, which leads to increasing number of requests for 25(OH)D determination, immunoassay measurements adjusted to automated analyzers are being developed. Because of the variability among assays, it is often difficult to monitor vitamin D status and supplementation. The aim of this study was to compare the results of two immunoassays with high performance liquid chromatography with ultraviolet detection (HPLC-UV). Also, the aim was to estimate vitamin D status, since up to date the prevalence of vitamin D deficiency in Serbia was not examined. We have evaluated analytical characteristics of two automated immunoassays for 25(OH)D determination, from Roche (CobasR e601) and Abbott (Architect). For comparison studies we used HPLC analysis of 25-(OH)-Vitamin D3/D2 from Chromsystems (Waters isocratic system). In order to estimate vitamin D status in general population, we have searched the database of the laboratory information system and analyzed the data from 533 patients whose 25(OH)D was determined together with intact parathyroid hormone (iPTH). For imprecision assessment, four serum pools were prepared with following 25(OH)D concentrations: 35 nmol/L, ∼50 nmol/L, ∼75 nmol/L and ∼125 nmol/L. Obtai ned CVs for Roche method were 1.5-2.8% for within-run and 4.0-6.7% for between-run imprecision. For Abbott method, CVs were 0.7-4.4% for within- run and 3.8-7.2% for between-run imprecision. Inaccuracy was analyzed with commercial control sera. Obtained deviations from target value were 2.1% for Roche assay and 1.3-1.5% for Abbott method, and were not statistically significant (P>0.05). Comparison of Roche and HPLC-UV methods using Passing-Bablok regression analysis gave the following equation for the regression line y=0.937x+9.518 (r=0.739; n=97) and the regression line equation from the comparison of Abbott and HPLC-UV methods was y=0.745x+10.343 (r=0.793; n=97). Mean difference and SD for Bland-Altman plot were -4.5 nmol/L and 21.75 nmo/L, respectively for Roche method and 6.4 nmol/L and 18.8 nmol/L, respectively for Abbott. Statistical analysis (Chi-square test) of frequency distribution among different vitamin D status categories (<25 nmol/L severe deficiency, 25-50 nmol/L deficiency, 50-75 nmol/L insufficiency and >75 nmol/L sufficiency) showed that the frequency distribution obtained with Abbott method was significantly different from the distribution of the HPLC results, in contrast to Roche results frequency distribution which did not differ significantly. Also, statistical analysis of the agreement between the three methods for each vitamin D status category showed that results of both Roche and Abbott methods were significantly higher than HPLC in the two deficiency categories (P=0.005 for Roche, P=0.0407 for Abbott), and in the sufficiency category Abbott method significantly underestimated concentration of 25(OH)D compared to HPLC results (P<0.0001). Median population values of 25(OH)D and iPTH were 41.8 nmol/L and 76.6 ng/L, respectively. ANOVA analyses showed significant (P<0.05) decrease in iPTH and Ca2+ concentrations across the 25(OH)D concentration categories. Stepwise multiple linear regression analysis indicated independent correlation of iPTH with 25(OH)D concentration (b=-0.290, P=0.0008). Also, one-way ANOVA with Student-Newman-Keuls test demonstrated that 25(OH)D concentrations measured in summer and autumn were significantly (P<0.001) higher compared to those determined in winter and spring. Despite acceptable imprecision and inaccuracy of both examined methods, results obtained with them did not correlate well with HPLC-UV (r<0.9), which was used as a reference. However, methods showed satisfactory ability to classify patients into vitamin D status categories, which is important for diagnosis of vitamin D deficiency and therapy follow-up. About two thirds (68.5%) of the examined po pulation had vitamin D deficiency (25(OH)D<50 nmol/L) and only 8% had sufficient 25(OH)D concentration (>75 nmol/L).

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Incidence of Hyperhomocysteinemia Among Patients With Acute Myocardial Infarction Younger Than 45 Years

Incidence of Hyperhomocysteinemia Among Patients With Acute Myocardial Infarction Younger Than 45 Years

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Isoelectrofocusing and PCR Amplification-Reverse Hybridization Assay in Evaluation of Alpha-1-Antitrypsin Deficiency

Isoelectrofocusing and PCR Amplification-Reverse Hybridization Assay in Evaluation of Alpha-1-Antitrypsin Deficiency

Alpha-1-antitrypsin deficiency is a potentially lethal genetic disorder, which has pulmonary and liver manifestations. The standardized biochemical and molecular diagnostic protocol for detection of clinically relevant alleles is needed. The paper summarizes current concepts about AATD, describes the potentials of isoelectric focusing and PCR amplification-reverse allele specific oligonucleotide hybridization assay in the detection of affected individuals and shortly presents our experiences in the evaluation of AATD. We conclude that the systematic clinical laboratory approach to AATD might be based on the combination of mentioned methods, coordinated by alpha-1-antritrypsin quantification. Additionally, its complete medical implementation is achieved through teamwork between clinical chemists, molecular biologists and clinicians.

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Lipid status association with 25-hydroxy vitamin D: Cross sectional study of end stage renal disease patients

Summary

Background

Some observational studies indicate an association of 25-hydroxy vitamin D (25(OH)D) insufficiency and atherogenic cholesterol concentrations. The aim of this study was to investigate relationship between 25(OH)D concentrations and lipid parameters in end stage renal disease (ESRD) patients, separately for predialysis, hemodialysis and peritoneal dialysis patients.

Methods

We have adjusted 25(OH)D concentrations for seasonal variability with cosinor analysis, and performed all further analysis using these corrected 25(OH)D concentrations. Concentrations of 25(OH)D and the lipid parameters were determined in 214 ESRD patients and 50 control group participants. The analysis included the measurement of 25(OH)D by HPLC, apolipoprotein (Apo) AI, ApoB and Lp(a) by nephelometry, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) by spectrophotometry and manually calculated ApoB/ApoAI and LDL-C/HDL-C ratio.

Results

ESRD patients with adjusted 25(OH)D concentrations of ≤ 50 nmol/L had significantly higher TC (P = 0.005) and ApoAI (P = 0.049). Significantly higher HDL-C (P = 0.011) and ApoAI (P = 0.020) were found in hemodialysis patients with the 25(OH)D concentrations of ≤ 50 nmol/L. The other analyzed lipid parameters differed significantly between predialysis, hemodialysis and peritoneal dialysis patients with 25(OH)D concentrations of < 50 nmol/L.

Conclusions

Our study indicate the significant relationship between 25(OH)D repletion and optimal concentrations of lipid parameters in ESRD patients. Further research is necessary to explain whether joint evaluation of vitamin D status and lipid abnormalities could improve cardiovascular outcome in ESRD patients.

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Introduction to Molecular Genetic Diagnostics / UVOD U MOLEKULARNU GENETIČU DIJAGNOSTIKU

Summary

Molecular genetic testing is part of modern medical practice. DNA tests are an essential part of diagnostics and genetic counseling in single gene diseases, while their application in polygenic disorders is still limited. Pharmacogenetics studies DNA variants associated with variations in drug efficacy and toxicity, and tests in this field are being developed rapidly. The main method for molecular genetic testing is the polymerase chain reaction, with a number of modifications. New methods, such as next generation sequencing and DNA microarray, should allow simultaneous analysis of a number of genes, even whole genome sequencing. Ethical concerns in molecular genetic testing are very important, along with legislation. After molecular genetic testing, interpretation of results and genetic counseling should be done by professionals. With the example of thrombophilia, we discuss questions about genetic testing, its possibilities and promises.

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Incidence of Hyperhomocysteinemia and Mthfr C677T Polymorphism Among Young Patients with Acute Myocardial Infarction

Incidence of Hyperhomocysteinemia and Mthfr C677T Polymorphism Among Young Patients with Acute Myocardial Infarction

Hyperhomocysteinemia is considered an independent risk factor for premature cardiovascular disease. Mutation MTHFR C677T reduces the activity of methylenetetra-hydrofolatereductase and may cause hyperhomocysteinemia. Incidence of hyperhomocysteinemia (homocysteine above 12 μmol/L), homocysteine level, and distribution of MTHFR C677T genotypes (C/C, C/T and T/T) are compared between young patients with acute myocardial infarction and healthy persons, matched by age. Study involved 86 patients younger than 45 years (77 men and 9 women) and 35 controls. Homocysteine was measured by an HPLC method and the MTHFR C677T genotype determined using PCR amplification and digestion with Hinf I. Statistical analyses included chisquare and Mann-Whitney U tests. Hyperhomocysteinemia was present in 32.6% patients and 14.3% controls, revealing a significant difference (P= 0.038). Median homocysteine levels in patients (10.4 μmol/L) and controls (9.6 μmol/L) were significantly different (P=0.035). Among patients, 50.0% had C/C, 41.9% C/T and 8.1% T/T genotype, and the genotype had no influence on hyperhomocysteinemia incidence and homocysteine level. Genotype distribution in patients was not significantly different from that observed in controls. The conclusion is that young patients with acute myocardial infarction have higher incidence of hyperhomocysteinemia and higher homocysteine levels than healthy young adults, while there is no significant difference in the distribution of MTHFR C677T genotypes.

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THE CLINICAL IMPORTANCE OF BIOCHEMICAL BONE MARKERS IN PATIENTS WITH ALCOHOLIC AND VIRAL LIVER CIRRHOSIS / KLINIČKI ZNAČAJ BIOHEMIJSKIH KOŠTANIH MARKERA KOD PACIJENATA SA ALKOHOLNOM I VIRUSNOM CIROZOM JETRE

Summary

Background Metabolic bone disease in patients with chronic liver disease is called hepatic osteodystrophy and is primarily a sequel to osteopenia/osteoporosis, and rarely secondary to osteomalacia. The aim of this work was to define the influence of vitamin D3 and parathyroid hormone (PTH) in the pathogenesis of hepatic osteodystrophy, as well as the predictive significance of biochemical bone markers.

MethodsThis prospective study included 58 male patients with alcoholic (49) and viral (9) cirrhosis. The concentrations of serum vitamin D3, PTH, osteocalcin and b-carboxy-ter - minal cross-linked telopeptide of type I collagen (b-CTX) were determined. Bone density was measured by dual energy X-ray absorptiometry in the L1-L4 spinal segment and the femoral neck.

Results Lower bone mineral density (BMD) was measured in 41 patients (70.7%). There was no significant correlation between PTH and vitamin D3 values and T score in the femoral neck (p=0.51; p=0.063) and lumbar spine (p=0.49; 0.064). Also, no significant correlation was found between the osteocalcin values in lumbar spine BMD (p=0.944) and femoral neck (p=0.161), or with b-CTX values and BMD in the lumbar spine (p=0.347) and femoral neck (p=0.73). Statistically significant difference was confirmed between the stage A osteocalcin (p=0.000) and b- CTX (p=0.008) values in relation to advanced stages B and C.

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Questionable Reliability Of Homocysteine As The Metabolic Marker For Folate And Vitamin B12 Deficiency In Patients With Chronic Obstructive Pulmonary Disease

Summary

Background: An increased homocysteine (Hcy) concentration may represent a metabolic marker of folate and vitamin B12 deficiency, both significant public health problems. For different reasons, patients with chronic obstructive pulmonary disease (COPD) are prone to these deficiencies. The study evaluates the reliability of Hcy concentration in predicting folate or vitamin B12 deficiency in these patients.

Methods: A group of 50 COPD patients (28 males/22 females, age (x¯±SD=49.0±14.5) years was enrolled. A chemiluminescent microparticle immunoassay was applied for homocysteine, folate and vitamin B12 concentration. Kolmogorov-Smirnov, Mann-Whitney U and χ2 tests, Spearman’s correlation and ROC analysis were included in the statistical analysis, with the level of significance set at 0.05.

Results: Average (SD) concentrations of folate and vitamin B12 were 4.13 (2.16) μg/L and 463.6 (271.0) ng/L, whereas only vitamin B12 correlated with the Hcy level (P=−0.310 (R=0.029)). Gender related differences were not significant and only a borderline significant correlation between age and folate was confirmed (R=0.279 (P=0.047)). The incidence of folate and vitamin B12 deficiency differed significantly (P=0.000 and P<0.000 for folate and vitamin B12 respectively), depending on the cut-off used for classification (4.4, 6.6 and 8.0 μg/L – folate; 203 and 473 ng/L – vitamin B12). ROC analyses failed to show any significance of hyperhomocysteinemia as a predictor of folate or vitamin B12 deficiency.

Conclusion: Reliability of the Hcy concentration as a biomarker of folate or vitamin B12 depletion in COPD patients is not satisfactory, so their deficiency cannot be predicted by the occurrence of HHcy.

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