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Open access

Jelena Jovanović and Dragan Denić

Abstract

A cost-effective method for resolution increase of a two-stage piecewise linear analog-to-digital converter used for sensor linearization is proposed in this paper. In both conversion stages flash analog-to-digital converters are employed. Resolution increase by one bit per conversion stage is performed by introducing one additional comparator in front of each of two flash analog-to-digital converters, while the converters’ resolutions remain the same. As a result, the number of employed comparators, as well as the circuit complexity and the power consumption originating from employed comparators are for almost 50 % lower in comparison to the same parameters referring to the linearization circuit of the conventional design and of the same resolution. Since the number of employed comparators is significantly reduced according to the proposed method, special modifications of the linearization circuit are needed in order to properly adjust reference voltages of employed comparators.

Open access

Jelena Nikolić, Zoran Perić, Dragan Antić, Aleksandra Jovanović and Dragan Denić

Low Complex Forward Adaptive Loss Compression Algorithm and Its Application in Speech Coding

This paper proposes a low complex forward adaptive loss compression algorithm that works on the frame by frame basis. Particularly, the algorithm we propose performs frame by frame analysis of the input speech signal, estimates and quantizes the gain within the frames in order to enable the quantization by the forward adaptive piecewise linear optimal compandor. In comparison to the solution designed according to the G.711 standard, our algorithm provides not only higher level of the average signal to quantization noise ratio, but also performs a reduction of the PCM bit rate for about 1 bits/sample. Moreover, the algorithm we propose completely satisfies the G.712 standard, since it provides overreaching the curve defined by the G.712 standard in the whole of variance range. Accordingly, we can reasonably believe that our algorithm will find its practical implementation in the high quality coding of signals, represented with less than 8 bits/sample, which as well as speech signals follow Laplacian distribution and have the time varying variances.

Open access

Jelena Jovanović, Dragan Denić and Uglješa Jovanović

Abstract

Optical rotary encoders generate nonlinear sine and cosine signals in response to a change of angular position that is being measured. Due to the nonlinear shape of encoder output signals, encoder sensitivity to very small changes of angular position is low, causing a poor measurement accuracy level. To improve the optical encoder sensitivity and to increase its accuracy, an improved linearization circuit based on pseudo-linear signal generation and its further linearization with the two-stage piecewise linear analog-to-digital converter is presented in this paper. The proposed linearization circuit is composed of a mixed-signal circuit, which generates analog pseudo-linear signal and determines the first four bits of the final digital result, and the two-stage piecewise linear analog-to-digital converter, which performs simultaneous linearization and digitalization of the pseudo-linear signal. As a result, the maximal value of the absolute measurement error equals to 3.77168·10−5 [rad] (0.00216°) over the full measurement range of 2π [rad].

Open access

Danijela Popović, Mirjana Paravina, Dragan Jovanović, Vesna Karanikolić and Dragana Ljubisavljević

Abstract

Lichen myxedematosus, also known as papular mucinosis, is a primary diffuse cutaneous mucinosis. It is a rare cutaneous myxedematous condition characterized by formation of numerous lichenoid papules. Scleromyxedema, also known as Arndt–Gottron syndrome, is a rare, confluent, papular and sclerotic variant of lichen myxedematosus, characterized by diffuse thickening of the skin underlying the papules. The condition is associated with systemic, even lethal manifestations, fibroblast proliferation and accumulation of acid mucopolysaccharides of the hyaluronic acid. Serum IgG class paraproteinemia is always present and it can be detected in all patients if appropriate or even repeat testing is used.

Herein, we present a 67-year-old patient with a 2-year history of skin problems. He had no health problems other than hypertension and diabetes, wich were both diagnosed 15 years before. On examination, the patient exhibited sclerodermoid lesions with diffuse pseudo-sclerodermatous thickening of the exposed skin, microstomia and sclerodactyly-like changes; on the face, there were numerous solid, shiny 2 - 4 mm in diameter skin-coloured lichenoid papules, scattered across the forehead, glabellar area, nasolabial folds, perioral region, ear lobes and the neck. Histopathological examination revealed: highly distinctive collagenosis and fibrosis in the middle dermis, increased fibroblasts; collagen bundles with irregular arrangement and fragmentation; alcian blue-positive deposits with appearance consistent with acid mucins. Serum protein electrophoresis detected IgG lambda paraproteinemia. The patient was treated with systematic corticosteroids during 9 months with subsequent introduction of methotrexate and showed satisfactory results.

The etiology of scleromyxedema remains unknown, since the purified IgG paraprotein itself has no direct effects on fibroblast proliferation. In scleromyxedema, numerous therapeutic modalities are proposed, unfortunatelly with limited effects.

In colclusion, we report a case of an adult male with lichenoid papules; after a two-year progression, they evolved into scleromyxedema and exhibited well response to conventional therapy.

Open access

Mirjana Paravina, Milenko Stanojević, Dragan Jovanović and Dragana Ljubisavljević

Abstract

Pachydermodactyly is a rare, benign form of digital fibromatosis, characterized by asymptomatic and progressive, periarticular and usually symmetrical soft tissue finger swelling, specifically on the lateral aspects of the proximal interphalangeal joints mainly of the second, third, and fourth fingers; it mostly affects young adolescents and is probably due to repeated mechanical injury of the skin (such as repeated clasping or rubbing of crossed fingers), sometimes as a result of obsessive-compulsive disorder, which must be distinguished from obsessive “chewing pads”. This paper presents a male patient aged 19, who presented with first symptoms at the age of 12, and was diagnosed with periarticular hypertrophy: localized soft tissue thickening around the proximal interphalangeal joints of all fingers except the thumbs; slight hypertrophy of the skin; absence of subjective complaints; normal joint function. Dermatological status on admission revealed: symmetrical soft tissue swelling of all fingers of both hands except the thumbs at the level of the proximal interphalangeal joints; normal appearance of the distal parts of all fingers; thickening at the level of the proximal interphalangeal joints, bilateral, almost symmetrical hypertrophy (ulnar and radial) of phalanges of the affected fingers except both index fingers, affecting only the ulnar side. The skin lesions were pain-free on palpation, with homogeneous texture and elastic consistency, freely movable over underlying structures. The affected joints showed no functional deficit. The test results, sonography, radiography and histopathology confirmed our clinical diagnosis-pachydermodactyly. The review of the currently available literature, published between 1973 and 2014, including 99 papers and 160 patients, provided important insight into the characteristics and variations of the disease.

Open access

Milena Jovanovic, Zeljko Todorovic, Dragan Milovanovic, Branislava Draskovic, Andreja Todorovic and Dejan Petrovic

Abstract

Prevalence of cognitive disorders is high in maintenance hemodialysis patients. Montreal cognitive assessment (MoCA) is used for detecting and evaluation of cognitive disorder degree in this patient population. In examined patient population, only 5 (12.5%) of them had normal cognitive function (MoCA ≥26). Mild cognitive impairment (MoCA 18-26) was found in 65.9% (29) patients, while moderate cognitive disorder (MoCA 10-17) was detected in 6 (21.6%) patients. Major cognitive disorder wasn’t detected in examined population. Statistically significant correlation was not established between laboratory parameters and overall MoCA score. Statistically significant correlation, however, was established between MoCA item that evaluates space and time orientation and intermediate secondary hyperparathyroidism and space and time orientation and severe secondary hyperparathyroidism. Hemodynamic instability during hemodialysis and silent ischemia of the brain are increasing risk of appearance of cognitive disorders in maintenance hemodialysis patients.

Open access

Mirjana Paravina, Dragan Jovanović, Milenko Stanojević and Ljiljana Nikolić

Abstract

Langerhans cell histiocytosis is a disease which results from accumulation or proliferation of a clonal population of cells with the phenotype of Langerhans cells arrested at an early stage of activation that are functionally deficient. The etiology and pathogenesis of the disorder are still unknown. There are ongoing investigations to determine whether it is a reactive or a neoplastic disease. The fact is that neoplastic and reactive processes may have many clinical and pathological similarities. Some emphasize the role of “cytokine storm” in Langerhans cells. Further studies are necessary in all areas, from the etiology and pathogenesis to diagnosis and therapy. Langerhans cell histiocytosis primarily affects bones, but less commonly it may involve other organ systems, or present as a multisystem disease. The clinical course is variable, from benign forms with spontaneous resolution, to chronic disseminated forms with fatal outcome. This is a report of a 29-year-old man with Langerhans cell histiocytosis with an onset at the age of 8, which later progressed to a multisystem disease. Apart from lesions on the skin and exposed mucous membranes, the patient also presented with: diabetes insipidus, granuloma of the right femur and slight bulbar protrusion of the right eye. The patient experienced spontaneous pneumothorax on two occasions. The diagnosis of Langerhans cell histiocytosis was histologically confirmed using electron microscopy by presence of Birbeck granules in the histiocytes. A favorable therapeutic response was obtained after systemic corticosteroid therapy.

Open access

Milena Jovanovic, Zeljko Todorovic, Dragan Milovanovic, Branislava Draskovic, Andreja Todorovic and Dejan Petrovic

Abstract

Prevalence of cognitive disorders is high in maintenance hemodialysis patients. Montreal cognitive assessment (MoCA) is used for detecting and evaluation of cognitive disorder degree in this patient population. In examined patient population, only 5 (12.5%) of them had normal cognitive function (MoCA ≥26). Mild cognitive impairment (MoCA 18-26) was found in 65.9% (29) patients, while moderate cognitive disorder (MoCA 10-17) was detected in 6 (21.6%) patients. Major cognitive disorder wasn’t detected in examined population. Statistically signifi cant correlation was not established between laboratory parameters and overall MoCA score. Statistically signifi cant correlation, however, was established between MoCA item that evaluates space and time orientation and intermediate secondary hyperparathyroidism and space and time orientation and severe secondary hyperparathyroidism. Hemodynamic instability during hemodialysis and silent ischemia of the brain are increasing risk of appearance of cognitive disorders in maintenance hemodialysis patients.

Open access

Danijela Jovanovic, Dragan R. Milovanovic, Nevena Jeremic, Tamara Nikolic, Isidora Stojic, Vladimir Jakovljevic and Natalija Vukovic

Abstract

Study aimed to investigate relationship between oxidative stress markers and postoperative recovery in woman after abdominal hysterectomy, as well as to test the hypothesis that different analgesics differently influence redox status.

The quality of recovery was evaluated with a QoR-40 questionnaire in fifty-one patients who underwent abdominal hysterectomy, preoperatively and on the 1st, 2nd, 3rd postoperative days (POD1,2,3). Blood samples were collected at baseline (T0), 3 (T1), 24 (T2), 48 (T3) and 72 (T4) hours after surgery. Oxidative stress markers concentrations (TBARS, NO2 , H2O2, O2 ) as well as antioxidative enzymes (SOD, CAT, and GSH) were analyzed.

QoR-40 total score significantly declined on POD1 and POD2 and returned to baseline levels on POD3 (p<0.001). H2O2 levels significantly decreased from T0 to T3 and then, increased at T4 (p=0,011). Changes of TBARS and H2O2 from T0 to T3 showed significant and negative correlation (r=−0.303, p=0.046). There was no significant correlation between QoR-40 total score and any parameter of oxidative stress response (p>0.05). Changes in TBARS levels from T0 to T3 were statistically significant between the study subgroups primarily due to increase of the concentrations in patients receiving paracetamol (p=0.031). Patients age, duration of surgery and cigarette smoking status showed significant influcences on and association with some oxidative stress response markers (TBARS, O2 , CAT) (p<0.05).

Women who underwent hysterectomy had significant changes of H2O2 and TBARS activity however, those changes were not associated with changes of QoR-40 total scores during recovery.

Open access

Jelena Bjelica, Ivan B. Jovanović, Vesna Ilić, Olivera Valčić, Danijela Kirovski, Dragan Gvozdić and Svetlana Milanović

Abstract

Both selenium, as an effector and regulator of antioxidative enzymes activity, and thyroid hormones are potent immunomodulators. Besides, selenium incorporated into iodothyronine deiodinases is involved in the thyroid function and thus indirectly regulates the immune response. Studies of the mutual influence of selenium and thyroid hormones on the immune response are scarce, hence we analyzed the effects of an iodothyronine deiodinases blocker, propylthiouracil (PTU), and selenium deficiency on the function of peritoneal macrophages, and titer of naturally occurring anti-sheep red blood cells (SRBC) IgM antibodies in juvenile rats. The experiment was carried out on 64 Wistar male rats allotted to 4 groups: controlselenium adequate PTU- group; selenium adequate, PTU+ group; selenium defi cient, PTU- group; and selenium defi cient, PTU+. The selenium adequate and selenium defi cient groups were fed a diet containing 0.334 and 0.031 mg Se/kg, respectively. PTU+ groups received PTU (150 mg/L) in drinking water. After 3 weeks, thyroxine (T4), triiodothyronine (T3), and thyroid stimulating hormone (TSH) were determined. The animals having “intermediate” concentrations of T3 (1.56-1.69 nmol/L) and T4 (41-50 nmol/L) were excluded from further analysis. Thus, PTU+ groups included hypothyroid animals (T3≤1.55 nmol/L; T4≤40 nmol/L), while PTU- groups included euthyroid rats (T3≥1.70 nmol/L; T4≥50 nmol/L). Both groups of selenium deficient rats had, when compared to the control group, a significantly lower activity of glutathione peroxidase GPx1 and GPx3. Neither selenium deficiency nor PTU influenced the adherence of peritoneal macrophages. Selenium deficiency significantly decreased the peroxide synthesis in macrophages and significantly increased the titer of anti-SRBC IgM. Hypotyroidism alone or in combination with selenium deficiency had no influence on these parameters.