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Snežana Jovičić

Biohemijski Aspekti, Laboratorijska Dijagnoza I Praćenje Povišene Koncentracije Holesterola: Preporuke NCEP ATP III

Treći izveštaj ekspertske grupe o detekciji, evaluaciji i tretmanu povišene koncentracije holesterola u odraslih (Adult Treatment Panel III, ATP III) predstavlja ažuriran klinički vodič Nacionalnog programa edukacije o holesterolu (National Cholesterol Education Program, NCEP), o određivanju holesterola i zbrinjavanju osoba s povišenom koncentracijom holesterola u serumu. Pored toga što preporučuje intenzivan tretman pacijenata sa koronarnom srčanom bolešću (coronary heart disease/CHD), važna karakteristika ATP III je težište na primarnoj prevenciji kod osoba sa više prisutnih faktora rizika. ATP III nastavlja da identifikuje povišene koncentracije LDL holesterola kao primarni cilj terapije za snižavanje holesterola. Osnovni princip prevencije je da se intenzitet terapije prilagođava apsolutnom riziku za CHD svake osobe pojedinačno. Procena rizika podrazumeva određivanje LDL holesterola u sklopu analize lipoproteina i identifikaciju pratećih determinanti rizika (prisustvo ili odsustvo CHD, drugih kliničkih oblika aterosklerotske bolesti i dijabetesa, pušenje, hipertenzija, niska koncentracija HDL holesterola, porodična anamneza prevremene pojave CHD, starost). U kategoriji najvišeg rizika nalaze se osobe sa CHD i CHD ekvivalentima rizika, čiji je apsolutni rizik od pojave srčane smrti ili nefatalnog infarkta miokarda u narednih 10 godina ≥20%. Drugu kategoriju čine osobe sa dva ili više faktora rizika kod kojih je 10-godišnji rizik <20%. Apsolutni rizik se procenjuje na osnovu Framingham rizik skora. U trećoj kategoriji su osobe sa jednim ili nijednim faktorom rizika. Definisane su preporučene koncentracije LDL holesterola za svaku kategoriju i postižu se korekcijom ishrane i/ili farmakoterapijom. Evropske preporuke za prevenciju kardiovaskularne bolesti (cardiovascular disease, CVD) u kliničkoj praksi preporučuju upotrebu SCO-RE (Systematic COronary Risk Evaluation) tablica za procenu rizika za pojavu CVD, koje podrazumevaju apsolutnu verovatnoću za fatalan ishod CVD u toku 10 godina. Cilj ovog rada je predstavljanje delova NCEP ATP III i evropskih preporuka značajnih za njihovu implementaciju u laboratorijsku praksu.

Open access

Snežana Jovičić, Svetlana Ignjatović and Nada Majkić-Singh

Comparison of Two Different Methods for Cardiovascular Risk Assessment: Framingham Risk Score and Score System

Numerous studies have shown that the major risk factors for coronary heart disease (cigarette smoking, hypertension, elevated serum total cholesterol and low-density lipoprotein cholesterol - LDL, low serum high-density lipoprotein cholesterol - HDL, diabetes mellitus and advancing age), are additive in predictive power. Accordingly, the total risk of a person can be estimated by summing up the risk imparted by each of the major risk factors. Using data obtained from population studies, various risk assessment algorithms have been developed. The aim of this study was to compare the two most common risk scores. Risk assessment for determining 10-year risk in 185 healthy, asymptomatic individuals of both sexes, 30-85 years old, was carried out according to both Framingham (FRS) and SCORE risk scoring. The risk factors included in the calculation of 10-year risk are gender, age, total cholesterol, HDL-cholesterol, systolic blood pressure, treatment for hypertension and cigarette smoking. The determinations of total cholesterol and HDL-cholesterol were made in sera collected after a 12h fasting period using an Olympus AU2700 automated analyzer. The Framingham risk score was determined using an electronic calculator - ATP III Risk Estimator, and the risk status according to SCORE was obtained using charts for the 10-year risk in populations at high risk. Among 185 participants, in 152 (82%) 10-year risk for Coronary Heart Disease (CHD) death was <10%, 24 (13%) had intermediate and 9 (5%) had high risk (⩾20%) according to FRS. According to SCORE, 110 (60%) participants had <1%, 56 (30%) had 1-5% and 19 (10%) had ⩾5% of 10-year risk for cardiovascular death. Different categories of risk were assigned to ~30% of individuals according to different risk assessment models. Differences in risk classification when using two different risk assessment algorithms can be explained with several important issues, including different endpoints, consideration of interactions and incorporation of antihypertensive use. It is important to note that neither FRS nor SCORE have been appropriately adjusted for our population, according to the national cardiovascular mortality rate.

Open access

Snežana Jovičić, Svetlana Ignjatović and Nada Majkić-Singh

Summary

Vitamin D is not technically a vitamin, since it is not an essential dietary factor. It is rather a prohormone produced photochemically in the skin from 7-dehydrocholesterol. Vitamin D and its metabolites may be categorized as either cholecalciferols or ergocalciferols. Cholecalciferol (vi - tamin D3) is the parent compound of the naturally occurring family and is produced in the skin from 7-dehydrocholesterol on exposure to the ultraviolet B portion of sunlight. Vitamin D2 (ergocalciferol), the parent compound of the other family, is manufactured by irradiation of ergosterol produced by yeasts and its potency is less than one-third of vitamin D3’s potency. The steps in the vitamin D endocrine system include the following: 1) the photoconversion of 7- dehydrocholesterol to vitamin D3 in the skin or dietary intake of vitamin D3; 2) metabolism of vitamin D3 by the liver to 25-hydroxyvitamin-D3 [25(OH)D3 ], the major form of vitamin D circulating in the blood compartment; 3) conversion of 25(OH)D3 by the kidney (functioning as an endocrine gland) to the hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3 ]; 4) systemic transport of the dihydroxylated metabolite 1,25(OH)2D3 to distal target organs; and 5) binding of 1,25(OH)2D3 to a nuclear receptor (VDR) at target organs, followed by generation of appropriate biological responses. The activation of vitamin D to its hormonal form is mediated by cytochrome P450 enzymes. Six cytochrome P450 (CYP) isoforms have been shown to hydroxylate vitamin D. Four of these, CYP27A1, CYP2R1, CYP3A4 and CYP2J3, are candidates for the enzyme vitamin D 25-hy - droxylase that is involved in the first step of activation. The highly regulated, renal enzyme 25-hydroxyvitamin D-1a-hy - dro xylase contains the component CYP27B1, which completes the activation pathway to the hormonal form 1,25(OH)2D3. A five-step inactivation pathway from 1,25(OH)2D3 to calcitroic acid is attributed to a single multifunctional CYP, CYP24A1, which is transcriptionally in du - ced in vitamin D target cells by the action of 1,25(OH)2D3. An additional key component in the operation of the vitamin D endocrine system is the plasma vitamin D binding protein (DBP), which carries vitamin D3 and its metabolites to their metabolism and target organs. DBP is a specific, high-affinity transport protein. It is synthesized by the liver and circulates in great excess, with fewer than 5% of the binding sites normally occupied. 1,25(OH)2D3, acts as a ligand for a nuclear transcription factor, vitamin D receptor - VDR, which like all other nuclear receptors, regulates gene transcription and cell function. The widespread presence of VDR, and the key activating (1a-hydroxylase, CYP27B1) and inactivating (24-hydroxylase, CYP24A1) en - zy mes in most mammalian cells means that the cells in these tissues have the potential to produce biological res pon ses, depending on the availability of appropriate amounts of vi - tamin D3. Thanks to this widespread presence of elements of vitamin D endocrine system, its biological features are being recognized outside bone tissue, i.e. calcium and pho - sphate metabolism.

Open access

Snežana Jovičić and Nada Majkić-Singh

Summary

Medical biochemistry is the usual name for clinical biochemistry or clinical chemistry in Serbia, and medical biochemist is the official name for the clinical chemist (or clinical biochemist). This is the largest sub-discipline of the laboratory medicine in Serbia. It includes all aspects of clinical chemistry, and also laboratory hematology with coagulation, immunology, etc. Medical biochemistry laboratories in Serbia and medical biochemists as a profession are part of Health Care System and their activities are regulated through: the Health Care Law and rules issued by the Chamber of Medical Biochemists of Serbia. The first continuous and organized education for Medical Biochemists (Clinical Chemists) in Serbia dates from 1945, when the Department of Medical Biochemistry was established at the Pharmaceutical Faculty in Belgrade. In 1987 at the same Faculty a five years undergraduate study program was established, educating Medical Biochemists under a special program. Since the academic year 2006/2007 the new five year undergraduate (according to Bologna Declaration) and four-year postgraduate program according to EC4 European Syllabus for Postgraduate Training in Clinical Chemistry and Laboratory Medicine has been established. The Ministry of Education and Ministry of Public Health accredited these programs. There are four requirements for practicing medical biochemistry in the Health Care System: University Diploma of the Faculty of Pharmacy (Study of Medical Biochemistry), successful completion of the professional exam at the Ministry of Health after completion of one additional year of obligatory practical training in the medical biochemistry laboratories, membership in the Serbian Chamber of Medical Biochemists and licence for skilled work issued by the Serbian Chamber of Medical Biochemists. In order to present laboratory medical biochemistry practice in Serbia this paper will be focused on the following: Serbian national legislation, healthcare services organization, sub-disciplines of laboratory medicine and medical biochemistry as the most significant, education in medical biochemistry, conditions for professional practice in medical biochemistry, continuous quality improvement, and accreditation. Serbian healthcare is based on fundamental principles of universal health coverage and solidarity between all citizens.

Open access

Snežana Jovičić, Svetlana Ignatović, Ranka Kangrga, Anđelo Beletić, Duško Mirković and Nada Majkić-Singh

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).

Open access

Milena Rakocevic, Biljana Popovska Jovicic, Tomislav Jocic, Stevan Matic, Goran Azanjac, Nemanja Jovicic, Vesna Stankovic and Snezana Jancic

Abstract

P53 is important for cell cycle regulation, and its overexpression is seen in malignant tumors. We examined correlation between p53 expression and cell proliferation, and its role in the pathogenesis of keratinocyte skin tumors. We used biopsies from patients with squamous cell carcinoma, actinic keratosis and keratoacanthoma. We examined crosssections stained with HE and using anti-cytokeratin, antip53 and anti-Ki67 antibodies.

Expression of p53 is found in 87, 85% of SCC, in 83. 3% of AK and 13. 4% KA. The high index of p53 expression was higher in SCC and AK compared to KA. We also observed a positive correlation between the expression of p53 and localization of the tumors. The largest proportion of subjects with AK and SCC has a high index of p53 expression on photoexposed region. We also observed that p53 expression correlates with age whereby in AK p53 expression increases with age. The high index of proliferation is most frequent in SCC and KA. Also at AK we found a strong correlation between a moderate proliferation index and tumor localization in photoexposed region. Between the proliferation index and p53 expression we observed a significant positive correlation only in SCC.

Proliferation index and the expression of p53 are useful for the differentiation of precursor keratinocyte lesions and skin carcinoma. High p53 expression has been associated with the aging and significantly correlates with the exposure to UV radiation in SCC and AK. High expression of p53 in AK and SCC supports the importance of this oncoprotein in carcinogenesis of the skin.

Open access

SAVIĆ Božidar, RADANOVIĆ Oliver, JOVIČIĆ Dubravka, NEŠIĆ Ksenija, IVANOVIĆ Snežana, STEVANČEVIĆ Ognjen, CVETOJEVIĆ Đorđe and KASAGIĆ Dragan

Abstract

A retrospective study on 235 natural cases of Porcine Respiratory Disease Complex in order to determine the etiological agents, their prevalence and interrelationships was performed in Serbia. Lung tissue samples were analyzed by Polymerase Chain Reaction for the presence of Porcine circovirus type 2, Porcine reproductive and respiratory virus, Swine influenza virus, Mycoplasma hyopneumoniae, Pasteurella multocida, Actinobacillus pleuropneumoniae, Haemophilus parasuis, Streptococcus suis and Arcanobacterium pyogenes. A total of 49 different combinations of viral and bacterial pathogens were found. Five different viral and viral/Mhp co-infections were detected. Monobacterial infections were found in 150 cases and polybacterial infection was detected in 85 samples. PCV2 was the main virus detected, and Pm was the most aggressive secondary pathogen detected in PRDC. The reason for PRDC being so prevalent among Serbian pigs is most likely due to the large number of risk factors in the conventional farrow-to-finish system, compared to multi-site production systems. Therefore, measures aimed at a better control of respiratory viruses, particularly Porcine circovirus type 2 and Porcine reproductive and respiratory virus, as well as Mycoplasma hyopneumoniae infections, and adoption of rational decisions on respiratory bacterial pathogens specific therapeutic and preventive strategies at herd level, simultaneously with significant improvements on farm management should reduce the occurrence of PRDC.

Open access

Spasoje Popević, Zorica Šumarac, Dragana Jovanović, Dragan Babić, Mihailo Stjepanović, Snežana Jovičić, Dragana Šobić-Šaranović, Snežana Filipović, Branko Gvozdenović, Maja Omčikus, Anđela Milovanović, Jelica Videnović-Ivanov, Ana Radović, Vladimir Žugić and Violeta Mihailović-Vučinić

Summary

Background: Until now, a proper biomarker(s) to evaluate sarcoidosis activity has not been recognized. The aims of this study were to evaluate the sensitivity and specificity of the two biomarkers of sarcoidosis activity already in use (serum angiotensin converting enzyme – ACE and serum chitotriosidase) in a population of 430 sarcoidosis patients. The activities of these markers were also analyzed in a group of 264 healthy controls.

Methods: Four hundred and thirty biopsy positive sarcoidosis patients were divided into groups with active and inactive disease, and groups with acute or chronic disease. In a subgroup of 55 sarcoidosis patients, activity was also assessed by F-18 fluorodeoxyglucose positron emission tomography (18F-FDG-PET) scanning. Both serum chitotriosidase and ACE levels showed non-normal distribution, so nonparametric tests were used in statistical analysis.

Results: Serum chitotriosidase activities were almost 6 times higher in patients with active sarcoidosis than in healthy controls and inactive disease. A serum chitotriosidase value of 100 nmol/mL/h had the sensitivity of 82.5% and specificity of 70.0%. A serum ACE activity cutoff value of 32.0 U/L had the sensitivity of 66.0% and the specificity of 54%. A statistically significant correlation was obtained between the focal granulomatous activity detected on 18F-FDG PET/CT and serum chitotriosidase levels, but no such correlation was found with ACE. The levels of serum chitotriosidase activity significantly correlated with the disease duration (P<0.0001). Also, serum chitotriosidase significantly correlated with clinical outcome status (COS) categories (ρ=0.272, P=0.001).

Conclusions: Serum chitotriosidase proved to be a reliable biomarker of sarcoidosis activity and disease chronicity.