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Patients with hematologic malignancies are at increased risk of severe forms of COVID-19 and have higher mortality, compared to patients with COVID-19 in the general population. The reasons for this include immunosuppression caused by the underlying hematologic disease and/or anticancer therapy received by these patients, advanced age, but also low levels of seroconversion after vaccination. These patients are also at a higher risk of getting infected because of frequent visits to health care facilities and high exposure to other patients. Results from published studies highlight the importance of prevention strategies in these patients, based on infection control measures and physical distancing, but also on well-timed vaccination. Risk factors which have proven to be crucial for severe forms of COVID-19 are age, the presence of comorbidities, malignancy type, progressive disease, and the type of oncologic therapy that these patients receive. Therefore, patients with hematologic malignancies represent a priority group for vaccination, which is recommended by all international professional associations. Considering that these patients are at risk of not developing an adequate immune response to the vaccine, the issues of determining the optimal time period for receiving the vaccine, the optimal dose, and the capacity of developing an immune response to the vaccine in specific groups of patients with hematologic malignancies, are questions that remain unresolved. Studies have shown that, despite the weak immune response to the vaccine, the mortality of vaccinated patients with hematologic malignancies is significantly lower than the mortality of unvaccinated patients. This article provides a review of relevant studies which analyze the characteristics, morbidity and mortality of patients with hematologic malignancies and COVID-19 and the role of vaccination in these patients.

The proportion of elderly people in the world population is constantly increasing. With age, the risk of numerous chronic diseases and their complications also rises. Research on the subject of cellular senescence date back to the middle of the last century, and today we know that senescent cells have different morphology, metabolism, phenotypes and many other characteristics. Their main feature is the development of senescence-associated secretory phenotype (SASP), whose pro-inflammatory components affect tissues and organs, and increases the possibility of age-related diseases. The liver is the main metabolic organ of our body, and the results of previous research indicate that its regenerative capacity is greater and that it ages more slowly compared to other organs. With age, liver cells change under the influence of various stressors and the risk of developing chronic liver diseases such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), alcoholic steatohepatitis (ASH) and hepatocellular carcinoma (HCC) increases. It has been proven that these diseases progress faster in the elderly population and in some cases lead to end-stage liver disease that requires transplantation. The treatment of elderly people with chronic liver diseases is a challenge and requires an individual approach as well as new research that will reveal other safe and effective therapeutic modalities.

Although, in the beginning, it was considered a respiratory infection with bilateral pneumonia as its main manifestation, COVID-19 is more of a multisystemic disease with various extrapulmonary manifestations. Cardiovascular manifestations are caused by direct viral involvement or by the effects of different cytokines on the myocardium and can occur during the acute phase of the disease or in the post-acute stadium. The most common cardiovascular symptoms in the post-acute COVID-19 stadium are fatigue, shortness of breath, chest pain, and palpitations. Routine cardiovascular diagnostics in these patients is usually without significant findings, although underlying myocardial inflammation may be present. Myocardial damage can also be the substrate for the worsening of heart failure and different potentially life-threatening arrhythmias, which is extremely important for further treatment and prognosis. Cardiac magnetic resonance imaging is a sophisticated, non-radiating imaging modality that can provide important information regarding left and right ventricle volumes and function, tissue characterization, and scar quantification. It is the golden standard in non-invasive diagnostics of myocarditis. In patients with prior COVID-19 infection and cardiovascular symptoms, typical signs of myocarditis, including myocardial edema, necrosis, and myocardial scarring, may be seen in cardiac magnetic resonance. Also, there are sophisticated cardiac magnetic resonance imaging modalities that can register subtle changes in the myocardium, in terms of myocardial inflammation, without visible signs in standard sequences. We present a case series of patients with different myocardial inflammation patterns, followed by a comprehensive review of potential pathophysiological mechanisms, complications, treatment and prognosis of patients with myocarditis or pericarditis after COVID-19.

The gastrointestinal tract and liver are not spared, when it comes to the coronavirus disease of 2019 (COVID-19), as it doesn't only affect the respiratory tract, but it is also a systemic disease that causes multiple organ damage. In this review, we have united all information that is clinically significant for physicians dealing with this infection, especially for gastroenterologists. One must bear in mind that gastrointestinal symptoms can be the first and/or only indicators of COVID-19, so this infection needs to be suspected when a patient at risk presents with diarrhea, loss of appetite, abdominal pain, nausea, and/or vomiting. Upper gastrointestinal endoscopy in the COVID-19 pandemic is a major issue, as transmission of this airborne infection happens very easily during this procedure, and it should be performed only in cases of gastrointestinal emergencies. With regard to patients suffering from inflammatory bowel disease (IBD), they are often on immunosuppressive therapy, but recommendations are that no change in therapy should be made, as these patients do not fall under the category of patients who are at increased risk of contracting COVID-19. In addition, liver lesion caused by this infection develops as the result of a multifactorial mechanism and is a definite cause for concern, especially in patients with pre-existing chronic liver conditions, who should be closely monitored.

Background: Functional dyspepsia (FD) is a syndrome mostly diagnosed by subjective patients’ symptoms after excluding organic, systemic and metabolic diseases. Aim: The goal of this study is to evaluate gastric emptying in patients with functional dyspepsia, by measuring the antral area (cm2) after the intake of a test meal using ultrasonography as an objective and widely applicable method. Material and Methods: This study included 30 patients (mean age of 46.53 ±9.73 years) with symptoms of FD according to the ROMA IV criteria and 30 healthy individuals (mean age of 42.87 ±4.42 years). A 5 MHz ultrasound probe was used to measure the stomach antral area at 6 different time points: in the fasting state, following the meal intake at 5, 30, 60, 90 and 120 min postprandially. Results: The antral area was statistically significantly larger after a 30-minute postprandial period in patients with FD comparing to healthy controls (p

Introduction. Risk stratification is an important aspect of COVID-19 management, especially in patients admitted to ICU as it can provide more useful consumption of health resources, as well as prioritize critical care services in situations of overwhelming number of patients. Materials and Methods. A multivariable predictive model for mortality was developed using data solely from a derivation cohort of 160 COVID-19 patients with moderate to severe ARDS admitted to ICU. The regression coefficients from the final multivariate model of the derivation study were used to assign points for the risk model, consisted of all significant variables from the multivariate analysis and age as a known risk factor for COVID-19 patient mortality. The newly developed AIDA score was arrived at by assigning 5 points for serum albumin and 1 point for IL-6, D dimer, and age. The score was further validated on a cohort of 304 patients admitted to ICU due to the severe form of COVID-19. Results. The study population included 160 COVID-19 patients admitted to ICU in the derivation and 304 in the validation cohort. The mean patient age was 66.7 years (range, 20–93 years), with 68.1% men and 31.9% women. Most patients (76.8%) had comorbidities with hypertension (67.7%), diabetes (31.7), and coronary artery disease (19.3) as the most frequent. A total of 316 patients (68.3%) were treated with mechanical ventilation. Ninety-six (60.0%) in the derivation cohort and 221 (72.7%) patients in the validation cohort had a lethal outcome. The population was divided into the following risk categories for mortality based on the risk model score: low risk (score 0–1) and at-risk ( score > 1 ). In addition, patients were considered at high risk with a risk score > 2 . By applying the risk model to the validation cohort ( n = 304 ), the positive predictive value was 78.8% (95% CI 75.5% to 81.8%); the negative predictive value was 46.6% (95% CI 37.3% to 56.2%); the sensitivity was 82.4% (95% CI 76.7% to 87.1%), and the specificity was 41.0% (95% CI 30.3% to 52.3%). The C statistic was 0.863 (95% CI 0.805-0.921) and 0.665 (95% CI 0.598-0.732) in the derivation and validation cohorts, respectively, indicating a high discriminative value of the proposed score. Conclusion. In the present study, AIDA score showed a valuable significance in estimating the mortality risk in patients with the severe form of COVID-19 disease at admission to ICU. Further external validation on a larger group of patients is needed to provide more insights into the utility of this score in everyday practice.

The emerging issues nowadays are non-alcoholic fatty liver disease (NAFLD) and its advanced stage non-alcoholic steatohepatitis (NASH), which further can be a predisposing factor for chronic liver complications, such as cirrhosis and/or development of hepatocellular carcinoma (HCC). Liver lipotoxicity can influence the accumulation of reactive oxygen species (ROS), so oxidative stress is also crucial for the progression of NASH. Moreover, NASH is in strong connection with metabolic disorders, and supporting evidence shows that insulin resistance (IR) is in a close relation to NAFLD, as it is involved in the progression to NASH and further progression to hepatic fibrosis. The major issue is that, at the moment, NASH treatment is based on lifestyle changes only due to the fact that no approved therapeutic options are available. The development of new therapeutic strategies should be conducted towards the potential NAFLD and NASH treatment by the modulation of IR but also by dietary antioxidants. As it seems, NASH is going to be the leading indication for liver transplantation as a consequence of increased disease prevalence and the lack of approved treatment; thus, an effective solution is needed as soon as possible.

Introduction. Mortality among critically ill COVID-19 patients remains relatively high despite different potential therapeutic modalities being introduced recently. The treatment of critically ill patients is a challenging task, without identified credible predictors of mortality. Methods. We performed an analysis of 160 consecutive patients with confirmed COVID-19 infection admitted to the Respiratory Intensive Care Unit between June 23, 2020, and October 2, 2020, in University Hospital Center Bezanijska kosa, Belgrade, Serbia. Patients on invasive, noninvasive ventilation and high flow oxygen therapy with moderate to severe ARDS, according to the Berlin definition of ARDS, were selected for the study. Demographic data, past medical history, laboratory values, and CT severity score were analyzed to identify predictors of mortality. Univariate and multivariate logistic regression models were used to assess potential predictors of mortality in critically ill COVID-19 patients. Results. The mean patient age was 65.6 years (range, 29–92 years), predominantly men, 68.8%. 107 (66.9%) patients were on invasive mechanical ventilation, 31 (19.3%) on noninvasive, and 22 (13.8%) on high flow oxygen therapy machine. The median total number of ICU days was 10 (25th to 75th percentile: 6–18), while the median total number of hospital stay was 18 (25th to 75th percentile: 12–28). The mortality rate was 60% (96/160). Univariate logistic regression analysis confirmed the significance of age, CRP, and lymphocytes at admission to hospital, serum albumin, D-dimer, and IL-6 at admission to ICU, and CT score. Serum albumin, D-dimer, and IL-6 at admission to ICU were independently associated with mortality in the final multivariate analysis. Conclusion. In the present study of 160 consecutive critically ill COVID-19 patients with moderate to severe ARDS, IL-6, serum albumin, and D-dimer at admission to ICU, accompanied by chest CT severity score, were marked as independent predictors of mortality.

Introduction. Triple-positivity (TP) or double-positivity (DP) for serum-specific immunoglobulin E (sIgE) antibodies against hornet venom (HV), wasp venom (WV) and/or honeybee venom (BV) causes significant problem in a selection of appropriate venom immunotherapy. However, DP/TP can be caused by cross-reactions resulting either from partial sequence identity of protein allergens in the venoms, or may be related to cross-reacting carbohydrate determinants (CCDs). Case report. A 60-year-old man was stung by a wasp and two days later by hornet. In both cases, within 15 minutes he developed hypotension and generalized urticaria and he was successfully treated with epinephrine, corticosteroids and fluids. After eight weeks, the examination revealed the negative skin prick test for all three venoms, but the sIgE-determination (ELISA, Biopharm) showed triple sensitization to native BV (0.55 IU/mL), WV (3.35 IU/mL) and HV (0.37 IU/mL). He was receiving the venom immunotherapy with venom mixtures for one year. In order to distinguish true multiple sensitization from cross-reactivity, the molecular-allergy testing by ImmunCAP with the CCD-free recombinant major allergens was performed. A high sensitization to Antigen 5-rVes v5 of WV (31.4 kU/L) was demonstrated while sIgE to phospholipase A2-rApi m1 of BV (0.15 kU/L) was negative; sIgE to CCDMUXF3- bromelain (0.75 kU/L) explained the sIgE-positivity for native BV. After these findings, a venom immunotherapy only with WV was initiated. Conclusion. In our patient, triple-IgE-positivity to native venoms detected by the ELISA was caused by cross-reactivity to CCDs. We recommend the molecular-allergy testing with the nonglycosylated recombinant allergens before starting the venom immunotherapy in patients with multiple-sIgE-positivity to native Hymenoptera venoms.

In this paper the realization and optimization of a novel coreless folded bus bar current transducer based on a Hall effect sensor are presented. The proposed transducer utilizes the bus bar folded in the shape of a Cyrillic letter “ $${\Pi }$$ ” to suppress impact of the skin effect, and it is capable of measuring AC and DC currents up to 250 A at 10 kHz frequency with nonlinearity less than $$\pm 0.5\%$$ in the entire current range. Methods for suppression of the skin effect impact and impact of stray magnetic fields are presented along with the experimental test results. Some of the proposed methods are novel and have never been evaluated.

A three-dimensional (3D) model of a high-power ultrasonic, composite, unidirectional transducer is proposed in this paper. The proposed 3D Matlab/Simulink model of the composite transducers predicts the thickness and the radial modes of oscillation as well as their mutual couplings. This longitudinal, prestressed, asymmetrical, piezoelectric transducer, which consists of two active piezoelectric layers, front, back and central oscillating metal mass, is realized. Due to its special structure, the central mass is not bounded using a bolt and performs unidirectional piston motion as compression and expansion occur in cycles keeping the axial dimension of the transducer roughly constant because of mutually opposite polarization of active elements. The electromechanical equivalent circuit of the transducer, representing one-dimensional (1D) model, is derived first and is also presented in this paper, while the resonance frequency equation is obtained analytically. Few composite transducers are designed and manufactured. Their resonance frequencies are measured and compared with the analytically obtained results for a large number of electrical connection combinations. In order to demonstrate the capabilities and limitations of the 1D model, comparison with the results from the 3D model are made. Results show that the measured frequencies are in good correspondence with the analytically obtained from 1D model only for the thickness modes and from the 3D model for the thickness and the radial modes of oscillation and their mutual coupling.

In this paper, we will present an artificial neural network (ANN) model trained to forecast hourly electricity consumption of energy in industry for a day-ahead. We will start with a brief analysis of the global electricity market with a special reference to the Serbian market. Next, the daily electricity consumption amounts between August 1st and December 19th 2019 will be analyzed using statistical tools. According to the obtained results, we will give predictions of our models, based on different number of previous days.

In this paper an overview of temperature sensors used for PV module temperature measurement is presented. Issues with contact temperature sensors, in the process of PV module temperature measurement, are explained in detail. Brief overview of related research is given, which includes analysis of measurement process and the presented results. Thorough research is conducted based on few commercially available temperature sensors, which include four contact and a single non-contact sensor. Measurement accuracy of all employed sensors was evaluated using a high-quality thermal imaging camera and the obtained measurement results are also presented. Temperature measurement, PV module, sensors, thermal imaging camera.

The paper provides an overview of coreless open-loop current transducers based on Hall effect sensor CSA-1V. Depending on the implementation method and current range, the presented transducers are divided in the four groups. The transducers are capable to measure AC and DC currents ranging from several tens of miliamperes up to several hundreds of amperes. Methods for resolving issues with the skin effect and stray magnetic fields are also presented including the experimental test results. Some of these methods are novelty and have never been presented in literature.