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  • Author: S. Ivanovs x
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The influence of cigarette design on the content of phenols in mainstream tobacco smoke was studied. The most abundant phenols - catechol, hydroquinone, phenol, o-, m-, and p-cresol, and resorcinol - were determined by HPLC with fluorescence detection. Hydroquinone and catechol made the most significant contribution to the total content of phenols with maximum values of 135.0 µg/cig and 95.7 µg/cig, respectively. The highest total content of phenols (330.9 µg/cig) was measured in the smoke of a Virginia tobacco cigarette. The total content of phenols (µg/cig) in cigarette mainstream smoke decreased linearly with increased filter ventilation, R2 = 0.9536. The results obtained indicate that filtration and ventilation can strongly influence the mainstream tobacco smoke content of phenol and its less polar derivatives, o-, m-, and p-cresol, which were reduced by up to 85%. Hydroquinone and catechol are less affected and only cigarettes with the special “recessed charcoal filter system” and cigarettes with filter ventilation over 50% showed significant reductions. On a per mg ‘tar’ basis the largest contributor to phenols in cigarette mainstream smoke was the selection of the tobacco type. The use of any standard commercial filter on an unfiltered cigarette can substantially reduce the yield of phenols in cigarette mainstream smoke. The use of special filters (e.g., the “recessed charcoal filter system”) or high levels of cigarette ventilation does not reduce the amount of phenols in tobacco smoke considerably when normalized on a per mg ‘tar’ basis.


As known, many multi-purpose plants can be used in different industries. This research is focused on the possibilities to utilize hemp as feedstock for thermal insulation products. The most advantageous features of hemp insulation are associated with health and environmental safety. The thermal conductivity of commercially available hemp insulation products is comparable with that of other fibrous insulation materials; however, it is possible to develop new products that could be more efficient in terms of cost and due to other important features.

Schemes for Compensation of Chromatic Dispersion in Combined HDWDM Systems

The authors seek best ways to realize chromatic dispersion (CD) compen-sation schemes for differently modulated optical signals in high-speed mixed data rate HDWDM systems. The research is based on OptSim 5.1. simulation software, which numerically solves nonlinear Schrödinger equation using the split-step Fourier method. It is shown that the CD compensation scheme is crucial for the performance evaluation in combined HDWM transmission channels. Therefore, a scheme of the type is proposed that is suited best for a very complicated combined fiber optical transmission system. It is also found that asymmetrical CD compensation schemes in pre- and post-compensation modules are the most efficient, allowing the best BER in a channel to be achieved.


Intellectual disability is affecting 3.0-4.0% of the general population. Copy number variants (CNVs) are a significant cause leading to neurodevelopmental disorders such as intellectual disability, epilepsy, autism spectrum disorders and developmental delay. The use of single nucleotide polymorphism (SNP)-array and array comparative genomic hybridization (aCGH) as diagnostic tools has led to the recognition of new microdeletion/microduplication syndromes associated with neurodevelopmental disorders. It is also useful for further characterization of marker chromosomes. Here, we report a girl with mild intellectual disability and mild facial dysmorphisms. Cytogenetic analysis showed a marker chromosome in some percent of the cells and was followed by SNP-array karyotyping that detected, in addition, a 9655 Mb de novo interstitial deletion at 9q21.1-9q21.2.


AIM: To suggest diagnostic combinations of symptoms for migraine and tension type headache (TTH), and for differentiation of overlapping headache (classified as either migraine or TTH) through evaluation of the diagnostic value of combinations of characteristics included in the International Headache Society diagnostic criteria for migraine and TTH in children and adolescents.

PATIENTS AND METHODS: The study comprised an epidemiological school-based study (412 of 1029 pupils with chronic / recurrent headache) and a clinical study conducted in the Pediatric Neurology Ward and outpatient clinic at Plovdiv Medical University Hospital (203 patients with chronic / recurrent headache). An inclusion criterion was at least two episodes of headache during the last year. Exclusion criteria were: headache occurring only during acute infections; withdrawal of informed consent. Headache was classified according to the International Classification of Headache Disorders 2nd edition (ICHD-II) The diagnostic value of all combinations of items in criteria C and D for migraine and TTH was measured by sensitivity, specificity, and odds ratio.

RESULTS: The combination “unilateral location, severe intensity, aggravation by physical activity” had 100% specificity for migraine. The combination “bilateral location, pressingtightening

quality, mild intensity, no aggravation by physical activity” had 100% specificity for TTH. The combinations: “migrainous location, severe intensity, aggravation by physical

activity”, “severe intensity, nausea”, “pulsating quality, nausea”, “pulsating quality, migrainous

location, aggravation by physical activity” seemed to pose the greatest risk for developing migraine. These combinations - “no nausea, no photophobia”, “bilateral location, mild intensity and either no aggravation by physical activity or pressing-tightening quality, or no nausea or no photophobia” increased the most the TTH risk. Using these combinations as additional criteria for overlapping headache we classi ed 50% of overlapping headache as TTH and 8.3% as migraine.

CONCLUSIONS: Some combinations of symptoms clarify the diagnosis of migraine and TTH. More than 50% of overlapping headache could be differentiated as TTH or MWA by the proposed combinations.


The aim of the study was to explore the impact of oxidative stress on frozen seminal plasma in fertile and infertile men by examining the total antioxidant capacity. Patients: Infertile patients from male infertility clinic with various diagnoses and fertile men. Design: Seminal plasma from proven fertile men [n=50] and infertile patients [n=50] were examined for total antioxidant capacity (TAC) level, semen parameters such as morphology, motility and concentration, and DNA integrity test. Interventions: Seminal plasma TAC measurement by luminometric assay using the TAC assay kit, semen analysis parameters, DNA integrity test. Fertile men showed higher TAC values (median and SD): 1201µM (SD±548), as compared with the infertile patients: 831μM (SD±343). The result from sperm morphology of fertile patients showed a mean percentage of 4.8 % (SD±1.68) whereas the percentage in the infertile group was 2.68% (SD ±1.68). The same group of samples, analyzed for DNA damage showed a mean of DFI 10.38% (SD±5.17%) in fertile men and a mean of DFI 17.22% (SD±7.22%) in infertile men. Total antioxidant capacity of the seminal plasma as measured by the luminоmetric assay is a reliable and simple test for diagnosing and management of male infertility.


Background: Most thyroid nodules are benign and do not need intervention. Toxic adenoma and toxic multinodular goiter (MNG) are common causes of hyperthyroidism, second in prevalence only to Graves’ disease. Toxic adenoma and MNG are the result of focal or diffuse hyperplasia of thyroid follicular cells whose functional capacity is independent from regulation by the thyroid stimulating hormone (TSH). When conservative treatment modalities fail to ensure an euthyroid state, surgical intervention is required, typically surgical left or right thyroid lobectomy. Radiofrequency ablation (RFA) is a new percutaneous treatment option that results in thermal tissue necrosis and fibrosis. As a result of this process, the thyroid nodules shrink.

Case presentation: We describe a case of a young woman with a large toxic thyroid adenoma who refused surgery. She was admitted to a one-day surgery unit and underwent radiofrequency ablation under total intravenous anesthesia. Using “moving shot technique” the procedure went uneventfully and the toxic adenoma displayed a significant volume reduction with resolution of the hyperthyroid symptoms. The patient also reported a significant improvement of her neck symptoms (from 7/10 to 1/10 on a Visual Analogue Scale).

Conclusions: Radiofrequency ablation is a new, well tolerated, safe and effective treatment option in selected patients with benign thyroid nodules, toxic adenomas of the thyroid gland and multinodular goiter. To the best of our knowledge, this is the first time such treatment modality is used in Bulgaria.


Considering the growing demand for broadband of access networks, in the present paper we investigate various modulation formats as a way of increasing the performance of optical transmission systems. Non-return-to-zero (NRZ) on-off keying, return-to-zero (RZ) OOK, carrier suppressed RZ (CSRZ) OOK, duobinary (DB), NRZ differential phase shift keying (NRZDPSK), RZ-DPSK and CSRZ-DPSK formats are compared using the maximal achievable reach with bit error rate less than 10−9 as a criterion. Simulations are performed by using OptSim software tool. It is shown that using the transmission system without dispersion compensation the best results are shown by duobinary and CSRZ-OOK modulation formats, but with the system using dispersion compensating fiber (DCF) the longest transmission distance is achieved by RZ-DPSK modulation format. By investigating the influence of channel spacing for best-performed modulation formats, network reach decrease for transmission systems with DCF fiber has been observed due to channel crosstalk.


Background: Development of biomarkers for autism spectrum disorder (ASD) has still remained a challenge to date. Recently, alterations of the expression of microRNAs (miRNAs) in peripheral blood, serum and post-mortem brain tissue have been linked to ASD. miRNAs are known to be secreted by various cell types and can mediate transmission of information into recipient cells and to modulate their physiological functions. On this basis it is assumed that circulating miRNAs could be useful biomarkers for the diagnosis or prognosis of pathological conditions.

Aim: The aim of this study was to test whether circulating miRNAs display differential expression profile in serum of ASD patients.

Patients and methods: The relative expression levels of 42 miRNAs were analyzed by stem-loop qRT-PCR assay in the serum of ASD patients compared to healthy controls.

Results: The results indicated that 11 miRNAs in ASD patients were substantially higher expressed than these in control subjects, and 29 miRNAs were lower expressed, respectively. In addition, target gene analysis displayed that the altered serum miRNAs targeted some important genes like alpha 1C subunit of voltage-dependent calcium channel, L type, (CACNA1C), beta 1 subunit of voltage-dependent calcium channel (CACNB1) and other genes involved in epigenetic processes like dicer 1, coding ribonuclease type III (DICER).

Conclusion: Our results suggested that differentially expressed miRNAs in serum might be involved in ASD molecular pathways, and serum miR-424-5p, miR-197- 5p, miR-328-3p, miR-500a-5p, miR-619-5p, miR-3135a, miR-664a-3p, and miR- 365a-3p might be able to serve as potential biomarkers for ASD because they displayed significant alterations in the expression profile in children diagnosed with ASD.


Pulmonary embolism (PE) is a relatively common cardiovascular emergency, though its exact incidence is difficult to assess. Accurate diagnosis is critical because of the high 30-day mortality in patients in whom the diagnosis is missed on admission. Doubt for PE is often raised by the presence of risk factors for venous thromboembolism (VTE), which are categorized into inherited and acquired. Among these, the importance of inherited/genetic thrombophilic factors is increasingly recognized. The most frequent markers of inherited thrombophilia are Factor V Leiden (FVL) and G2021OA prothrombin gene mutation. Among the inherited factors causal to thrombophilia, the C677T variant in methylentetrahydrofolate reductase (MTHFR) gene as well as factors like P1A1/P1A2 polymorphism in platelet glycoprotein Ilb/IIIa (P1A2) and hypofibrinolytic polymorphism 4G/4G in PAI-1 gene are discussed with controversial results. In our study, thrombophilic and hypofibrinolytic genetic variants were identified in 54.2% of 115 patients with PE. The most common significant genetic defects were FVL- 16.5% in patients versus 6.2% in controls (OR=3.102; p=0.05), G20210A PT 5.7% versus 2.1% (OR=2.983; p>0.05). P1A2 was found in 27.3% patients versus 19.9% in controls (OR= 1.523, p>0.05) and PAM 27.8% versus 22.6% (OR =1.501 p>0.05). MTHFR C677T carriage was inverse: 6.7% in patients versus 13.4% in controls. (OR=0.461 p=0.05). Of all the patients studied, 15.65% had a history of recurrent embolic incidents. The risk of recurrence was higher for the carriers of FVL and G20210A prothrombin gene mutation. The association between carriage of thrombophilic genetic factor and the early onset of the first embolic episode was found in the patients with PE. The awareness of risk factors and risk stratification is a critical issue in treatment and prevention policy. Preventive measures should be taken in particular medical conditions.