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  • Author: I. Dimitrova Ivanova x
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I. Dimitrova Ivanova, B. Atanasova, S. Dragneva, L. Vladimirova, Z. Krastev, A. Kostadinova, A. Ivanova and K. Tzatchev


Pre-analytical factors of variation need to be carefully considered and investigated in efforts to harmonize all aspects of the total testing process. This study aimed to evaluate contamination and stability in copper (Cu) analysis of serum and urine by flame atomic absorption spectroscopy (FAAS) and to compare the stability of urine Cu in controls and in D-penicillamine (D-PA) administration. Cu was measured by AAnalyst 400, Perkin Elmer, USA. Blood was collected in BD Vacutainer®SSTTM II Advance tubes and BD Vacutainer® Trace Element tubes. Sterile polyethylene and polypropylene vessels for collection, transportation, storage and preliminary preparation of samples were used in urinalysis. Stability in serum and 24 h urine was evaluated in two temperature regimens: 15-25°C and 2-8°C, for particular time of storage. No significant differences (p = 0.20) in Cu concentration was found between the two types of tested tubes with patient`s sera. The stability of the samples (serum and urine) was better at refrigeration temperature. In urine the stability was better in D-PA administration.Standardization of Cu analysis could be achieved by assessing the aspects of pre-analytical factors of variations.

Open access

I. Ivanova, B. Atanasova, A. Kostadinova, Y. Bocheva and K. Tzatchev


Copper (Cu) and zinc (Zn) are essential for life. Body Cu and Zn content depends on variety of factors - age, gender, and diet, type of drinking water, geographical location and genetic predisposition. Copper status becomes even more relevant not only in rare genetic disorders such as Wilson disease but in diseases such as cardiovascular ones, impaired glucose tolerance and neuro-degenerative and tumor diseases. The study aimed to examine the distribution of serum Cu and Zn in a representative group of the Bulgarian population and to describe factors which influence metal content. It also aimed to describe the link between serum Cu levels and the frequency of Alzheimer’s disease (AD) in Bulgarians. Cu and Zn in serum were measured in 379 individuals (172 males and 207 females) from 5 different regions in Bulgaria by flame atomic absorption using AAnalyst 400, Perkin Elmer. Statistical analyses were performed by SPSS, 19. Median and inert-quartile range (IQR) for blood Cu were 15.89 (13.87-7.89) μmol/L and for Zn - 13.00 (11.7-14.68) μmol/L in the examined group. Higher Cu levels in females than in males were found (p < 0.001). Decrease of Zn with aging was established (p > 0.05). Significant difference (p < 0.05) was found in serum Cu between young people (< 30 year old) and adults over 61 year old. Statistically significant difference in Cu and Zn was observed (p < 0.05) in respect of residences. Difference without significance was measured between serum lipids and serum Cu (p = 0.541) and Zn (p = 0.741).

Open access

Sofiya L. Ivanova, Dimitrichka J. Dimitrova, Metodi H. Petrichev, Liliana I. Parvanova, Georgi Sl. Kalistratov and Lubomir T. Vezenkov


The pharmacokinetics of zinc was investigated in broiler chickens after single crop intubation of 50 mg/kg 5% zinc aspartate suspension in 2% carboxymethyl cellulose solution. Blood serum zinc concentrations were assayed on a biochemical analyzer. The pharmacokinetics of zinc was evaluated using two approaches – compartmental method and non-compartmental analysis using pharmacokinetic software (TopFit, v. 2.0). After the intraingluvial application, zinc was rapidly absorbed (t1/2abs. =0.1040.02 h) by the alimentary system of birds attaining Cmax of 63.603.94 mol/ml by hour 0.77 (compartmental method) and Cmax =69.274.35 mol/ml by hour 0.92 h (non-compartmental method). It is characterized with a long biological half-life (t1/2) of 13.821.63 h (compartmental analysis) and 15.961.73 h (non-compartmental analysis) and long mean residence times (MRT) 20.122.35 h and 23.002.50 h, respectively. The distribution in blood and extracellular fluid was good as seen from Vd(area) values 0.770.05 l/kg (compartmental analysis) and 0.650.05 l/kg (non-compartmental analysis).

Open access

Vania M. Youroukova, Denitsa G. Dimitrova, Anna D. Valerieva, Spaska S. Lesichkova, Tsvetelina V. Velikova, Ekaterina I. Ivanova-Todorova and Kalina D. Tumangelova-Yuzeir


Background: Bronchial asthma is a heterogeneous disease that includes various subtypes. They may share similar clinical characteristics, but probably have different pathological mechanisms.

Aim: To identify phenotypes using cluster analysis in moderate to severe bronchial asthma and to compare differences in clinical, physiological, immunological and inflammatory data between the clusters.

Patients and methods: Forty adult patients with moderate to severe bronchial asthma out of exacerbation were included. All underwent clinical assessment, anthropometric measurements, skin prick testing, standard spirometry and measurement fraction of exhaled nitric oxide. Blood eosinophilic count, serum total IgE and periostin levels were determined. Two-step cluster approach, hierarchical clustering method and k-mean analysis were used for identification of the clusters.

Results: We have identified four clusters. Cluster 1 (n=14) - late-onset, non-atopic asthma with impaired lung function, Cluster 2 (n=13) - late-onset, atopic asthma, Cluster 3 (n=6) - late-onset, aspirin sensitivity, eosinophilic asthma, and Cluster 4 (n=7) - early-onset, atopic asthma.

Conclusions: Our study is the first in Bulgaria in which cluster analysis is applied to asthmatic patients. We identified four clusters. The variables with greatest force for differentiation in our study were: age of asthma onset, duration of diseases, atopy, smoking, blood eosinophils, nonsteroidal anti-inflammatory drugs hypersensitivity, baseline FEV1/FVC and symptoms severity. Our results support the concept of heterogeneity of bronchial asthma and demonstrate that cluster analysis can be an useful tool for phenotyping of disease and personalized approach to the treatment of patients.