Search Results

You are looking at 1 - 8 of 8 items

  • Author: Borislav Dimitrov x
Clear All Modify Search

Abstract

Only few follow-up studies have studied in detail the role of most important risk factors, but no reports were found on critical values (cut-offs) for such factors in prospectively predicting cerebrovascular events (CVE) in patients with minor ischaemic stroke (MIS). Estimates of predictive importance of such cut-offs may better inform and contribute to optimize treatment. This was a post-hoc modelling study with unique data from Bulgaria on 54 consecutive patients with MIS, aged ł 40, followed for 12 months for nonfatal or fatal CV events. A set of routine clinical demographic and known risk factors (SBP, DBP, HDL cholesterol, etc.) were explored using univariate statistics and multivariate regression models to identify the most important independent predictors of secondary CVE. An artificial neural network (ANN) model, irrespective of usual statistical constraints, also confirmed the specific role and importance of identified predictors. A receiver operating characteristics (ROC) curve and stratified survival analyses were used to define the best cut-off of most important predictors and validate the final model. During follow-up period of 11.1±2.4 months, 8 secondary CV events (14.8%) were observed only in males with MIS at the 5.8±2.7 months mark. No difference in age of patients with CV event (61.1±12.6 years) vs. those without (62.1±9.6 years) was found (p>0.05). The one-year risk for CVE was.15% (95%CI 7.1, 27.7%). The two most important risk factors in patients with versus without CV events were acute MIS onset (62.5 vs. 13.0%) and mean DBP at day 30 post-MIS (101.3±9.9 vs. 92.3±10.8 mmHg), with a relative importance by ANN of 20.92 versus 15.9 points, respectively. At multivariate logistic analysis only MIS onset and DBP were independently associated with the risk for secondary CVE (79.6% model accuracy, p model=0.0015). An increase of DBP with 1 mmHg was associated with 8% higher risk of CVE [adjusted OR=1.08 (95%Cl 1.004, 1.158)]. With this method, a novel cut-off predictive DBP value of 95 mmHg (ROCAUC=0.79, 95%Cl 0.60, 0.99, p=0.009) for CV events in patients with MIS has been found. In conclusions the new DBP cut-off (sensitivity >87%, specificity >69%) clearly discriminated between absence and presence of secondary CVE as also confirmed by stratified survival analysis (7 vs. 1 events, plog-rank =0.0103). This cut-off may be applied to better precisely evaluate and define, as earlier as possible, MIS patients at increased risk of secondary CV events.

Abstract

This article presents a 2D visualization of stellar spectra, obtained in Rozhen NAO.The aim is to convert one-dimensional arrays into two-dimensional images with the possibility of adjusting the degree of gray. This allows us to visualize the curves of the radial velocities and to determine their half-amplitudes even more precisely. The results of the observed stars NSVS 254037 and TYC3621-711 are presented.

Abstract

Subarachnoid hemorrhage (SAH) occurs primarily during early to mid-adulthood; approximately 30% of individuals with SAH die within 2 weeks, and mortality is 30% to 45%. SAH happens suddenly, without patients being aware of previous heart abnormalities. Here, we performed a pilot single cohort (historical) study to examine the hypothesis that early abnormal electrocardiographic (ECG) changes may reveal unknown but “silent” heart pathologies in SAH patients without previous heart disease (PHD). Data were collected retrospectively on 56 consecutive patients during the acute phase of SAH (29 men, 27 women; mean age 49.0 ± 6.2 years) with different degrees of neurologic deficit (Hunt-Hess scale assessment) in a 2-year period single-cohort study. Repolarization abnormalities were most frequent (p<0.05) and were independent of a history of PHD, although it corresponded to a higher risk for such abnormalities (odds ratio OR=3.21; CI95%=1.01–10.22). ECG changes in patients without PHD were similar to those in PHD patients, confirming the hypothesis that SAH is associated with previously “silent” heart pathology. The increased frequency of ECG changes in PHD patients and their high incidence in no-PHD patients suggested a neurogenic form of myocardial dysfunction following SAH. Notably, repolarization changes were more frequent in patients with less severe deficit (p<0.05), whereas rhythm and conductive abnormalities were more frequent in patients with more severe neurologic deficit.

Abstract

Best available descriptions of malaria incidence and mortality dynamics are important to improve and evaluate the implementation of programs to monitor (e.g., remote sensing) and control disease, especially in endemic zones. High-frequency (e.g., semi-annual and seasonal) cycles in malaria incidence have been observed in various countries and they coincide with cycles in the natural environment (e.g., temperature, heliogeophysical activity, etc.). However, neither trend nor cyclical oscillations beyond a 6-month (0.5-year) period for this vector-borne disease were reported in a recent analysis on monthly notifications in Burundi for the years 1997–2003. Since the examination of graphical plots indicated an eventual existence of trans-year (multiannual) variations, we further analyzed the same data in more detail. Here we explore whether low-frequency cycles (beyond seasonality) might exist (e.g., trans-year cycles with periods of 13–24 months or longer). Monthly incidence rate per 100 inhabitants from the Province of Karuzi, Burundi, over the years 1997–2003 was analysed. The exploration of underlying chronomes (time structures) was done by linear and non-linear parametric regression models, autocorrelation, spectral analysis (e.g., fast Fourier transforms), periodogram regression analysis (PRA) and wavelet transform (WT). By using a periodogram regression analysis, we describe a multicomponent cyclic chronome with periods T>12 months (19 and 86 months, all at P<0.05). Notably, the strongest cyclic pattern in the periodogram of the detrended malaria rates (whereas the peak was suppressed and beyond the semi-annual cycle of 6 months) was ≈1.5–1.6 years (T=19.0 months, R=0.32). A dynamic pattern of “shortening” of the length (period) of the cycles was observed during the pre-epidemic interval (from 8–9 to 5–6 months and from 20–22 to 16–18 months in years 1997–2000) that can be used to anticipate a forthcoming incidence increase and epidemic levels of malaria at a regional level. Indeed, these cycles in malaria incidence correspond to cyclic components of heliogeophysical activity (HGA) such as the sunspot cycle impulses of 0.5–2.0 years as well as the quasi-biennial solar magnetic cycle of 1.5–2.5 years and further, detailed analyses are warranted to investigate such relationships. A multicomponent dynamic cyclical pattern of malaria incidence variations in Burundi (1997–2003) exists thus allowing further, more specific analyses and modelling as well as correlations with similar environmental cycles to be explored. These results might also contribute to better estimates for forecasting, prevention and understanding of malaria dynamics and aetiology.

Summary

Psoriasis isachronic autoimmune multisystem disease, mainly affecting the skin and joints. Its origin is related to both environmental and genetic factors. The condition affects 1-3%of the population worldwide. Psoriasis is also associated with cardiovascular risk factors, atherothrombotic events, and markers of hypercoagulation (platelet activation and hyperhomocysteinemia). Venous thromboembolism (VTE) isawidespread severe disease. Both VTEand psoriasis are connected with risk factors for cardiovascular disorders (obesity and hypertension). The incidence of VTEevents in patients with psoriasis is higher. Patients with psoriasis should be checked for risk factors (metabolic disorders and cardiovascular diseases).We reportacase of a 53-year old man, diagnosed with plaque psoriasis 20 years ago, andafive year history of hypertension. In 2006, he hadastroke, and in 2011 ‒aheart attack. In 2013 he was diagnosed with thrombophlebitis. The patient was recently diagnosed with Type IIdiabetes, dyslipidemia and metabolic syndrome. The DNAanalysis revealed that the patient wasahomozygous carrier of 4G/4G (rs1799889) polymorphism in plasminogen activator inhibitor 1 (PAI-1) -a risk factor for thrombophilia. This case is important because of the major comorbidities, more particularly thrombotic events in combination withaprothrombotic mutation.

Summary

In the last 15 years, sentinel lymph node biopsy (SLNB) for patients with malignant melanoma (MM) has been introduced into the clinical practice. Our aim was to make a retrospective analysis of clinical results in order to assess the success ratio of SLNB and the variables affecting it in MM patients, treated in the Oncology Center at the University Hospital “Dr George Stranski” - Pleven, Bulgaria for a 4-year period. A research index card was used to process the oncologic files of 82 out of 102 patients with MM, treated and monitored at the Oncology centre between 01.01.2008 and 31.12.2011. TNM-stages, Breslow and Clark levels, location, characteristics of the skin lesion, diagnostic excision, type of lymph node dissection, number of SLN, localization of SLN, etc. were registered in the index card. SLNB staging was carried out in 28 patients. Sentinel lymph nodes were found in 22 of them. The success ratio of the method was 78.6%. Histologically, metastatic SLN were found in 4 cases. The Patent Blue Dye method was used in 22 of the cases (78%). A combined radiocolloid and dye method was used in 5 cases (18%). A radiocolloid method was used in 1 case (4%) only. Our research showed that more therapeutic lymph node dissections were performed in cases of locally advanced MM, which in turn worsened the clinical results. According to our research, the SLNB success ratio depends on the precision of diagnostic excision (p=0.019), lesion location (p=0.015), Clark level (p=0.0229), mapping method (p=0.08) and the type of melanoma (p=0.088).

Abstract

This short communication presents a second version of the program SpectraView (SV2). The Second Version of SpectraView for Spectra Analysis is based on data collected with 2-m RCC telescope at Rozhen National Astronomical Observatory. This version is equipped with new user interface and other features unavailable in its previous versions. It has also been created using modern programming language and is now compatible with the latest operating systems. The program has been tested on the observations of the five short-period variable stars.