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D Babic

Publications and source records attributed to D Babic.

At least 19 recordsLinked to original sources
PubMed2006

Anisotropic laser trapping in nematic colloidal dispersion.

The interaction between a colloidal particle and a focused laser beam in a nematic liquid crystal reveals an unusual anisotropic Coulomb-like character. Experiments demonstrate two opposite directions in which the particle is attracted to and repelled from the nematic region deformed by the light-induced director reorientation. In this work we present analytical analysis of such behavior and derive the energy of interaction between colloidal particle and deformed director field. The analytical solution is in good agreement with recent results obtained by computer simulation.

Colloids↗
PubMed2006

Laser trapping of low refractive index colloids in a nematic liquid crystal.

We describe and analyze laser trapping of small colloidal particles in a nematic liquid crystal, where the index of refraction of colloids is smaller compared to the indices of the liquid crystal. Two mechanisms are identified that are responsible for this anomalous trapping: (i) below the optical Fréedericksz transition, the trapping is due to the anisotropic dielectric interaction of the polarized light with the inhomogeneous director field around the colloid, (ii) above the optical Fréedericksz transition, the optical trapping is accompanied by the elasticity-mediated interaction between the optically distorted region of a liquid crystal and the colloid. In the majority of the experiments, the trapping above the Fréedericksz transition is highly anisotropic. Qualitative agreement is found with a numerical analysis, considering the nematic director elastic distortion, dielectric director-light field coupling and optical repulsion due to low refraction index colloid in high index surroundings.

Journal Article↗
PubMed2005

3D roadmap in neuroangiography: technique and clinical interest.

We present the first clinical results obtained with a novel technique: the three-dimensional [3D] roadmap. The major difference from the standard 2D digital roadmap technique is that the newly developed 3D roadmap is based on a rotational angiography acquisition technique with the two-dimensional [2D] fluoroscopic image as an overlay. Data required for an accurate superimposition of the previously acquired 3D reconstructed image on the interactively made 2D fluoroscopy image, in real time, are stored in the 3D workstation and constitute the calibration dataset. Both datasets are spatially aligned in real time; thus, the 3D image is accurately superimposed on the 2D fluoroscopic image regardless of any change in C-arm position or magnification. The principal advantage of the described roadmap method is that one contrast injection allows the C-arm to be positioned anywhere in the space and allows alterations in the distance between the x-ray tube and the image intensifier as well as changes in image magnification. In the clinical setting, the 3D roadmap facilitated intravascular neuronavigation with concurrent reduction of procedure time and use of contrast medium.

Cerebral Angiography↗
PubMed2005

Colloids as model systems for problems in statistical physics.

Owing to their mesoscopic length scales, colloidal suspensions provide ideal model systems suitable for addressing many problems in the field of statistical physics. Exemplarily, we highlight the versatile nature of such systems by discussing experiments with stochastic resonance and a practical realization of a recently proposed ratchet cellular automaton.

Algorithms↗
PubMed2005

Radical radiotherapy for localized prostate cancer in elderly.

BACKGROUND: Prostate cancer is an age related neoplasm, with high incidence in the group of elderly man. The correct management must to be balanced between the benefits of the treatment and its disadvantages. Radiotherapy as definitive treatment is commonly reserved for older patients and patients with high surgical risk and is widely used as a treatment of choice. AIM: The aim of this study was to determine the role of radical radiotherapy for localized prostate carcinoma in patients 70 years age or older concerning treatment morbidity, local control, disease free and overall survival. MATERIAL AND METHODS: A clinical prospective non-randomized study was performed including 103 elderly patients with an age 70 or above, between January 1991 and April 2005, at the Institute for Oncology and Radiology of Serbia. Median age of patients was 74,89 years (range 70- 80 years). Stage distribution was as follows: stage A--3 patients (2.9%), stage B--69 patients (67%) and stage C--31 patients (30.1%). Out of 103 patients, initial PSA value was noted in 87 patients. The mean value of initial PSA was 18,06 ng/ml. Radical radiotherapy was conducted on megavoltage linear accelerators with high energy photons (10, 18 MeV) and total tumor dose of 65 Gy. RESULTS: Low grade acute complications were registered in 70 patients (65%). Mean follow up time was 40, 13 months. The disease outcome at the last follow up show that 79 patients (76.7%) had no evidence of disease and 24 patients (23.3%) relapsed. Overall survival rates were 65, 29% and 44, 52% and disease free survival 66, 59% and 63, 26% at 5 and 10 years. Disease specific survival was at 5 and 10 years 73,32% and 65, 42% respectively. Late sequelas (gradus I and II) are registered in 22 patients (21.36%), out of 103. CONCLUSION: Radical radiotherapy for localized carcinoma of the prostate is effective treatment option in elderly patients with good local control, present treatment tolerance providing good quality of life and long-term cure.

Adenocarcinoma↗
PubMed2004

Laser trapping of small colloidal particles in a nematic liquid crystal: clouds and ghosts.

We show that, contrary to intuition, small (< or =1 microm) transparent particles can be trapped and manipulated in a nematic liquid crystal using an intense laser beam, although their index of refraction is lower than both refractive indices of the surrounding birefringent fluid. Two mechanisms are identified that are responsible for this anomalous trapping: (i) surface-induced distortion of the birefringent media around the particle, creating a high-index "cloud" around the colloid, and (ii) laser-induced distortion or (partial) melting of a nematic, creating a ghost colloid.

Journal Article↗
PubMed2004

A significance of immunohistochemical determination of steroid receptors, cell proliferation factor Ki-67 and protein p53 in endometrial carcinoma.

OBJECTIVES: The aim of the study was to preoperatively predict the biologic behavior of the endometrial carcinoma using immunohistochemical analysis of the p53 protein and Ki-67 expression, and estrogen receptor (ER) and progesterone receptor (PR) status, in the material obtained by fractional curettage. METHODS: One hundred and thirty-six patients with primary endometrial carcinoma were included in the study. In all 136 patients, the fractional curettage was performed before the hysterectomy, and the diagnosis of endometrial carcinoma was confirmed pathohistologically after the surgical procedure on the hysterectomy specimens. The significance of the prognostic factors was assessed using univariate and multivariate analyses. The cutoff values of the percentage of ER, PR, p53, and Ki-67 positive cells in terms of survival probability determination were obtained as the values of the highest chi-square test, using proportional-risk regression method. A multivariate Cox regression analysis was performed to estimate the influence of several clinical, pathohistologic, and immunohistochemical covariates to patients' survival. Survival curves were determined by the Kaplan-Meier product-limit method based on the most recent clinical status. RESULTS: According to the histologic type of the tumor, fractional curettage specimens revealed 111 histologically favorable types (81.6%) and 25 unfavorable types (18.4%). The data indicate that ER, PR, Ki-67, and p53 levels of the hysterectomy specimens and those of the preoperative specimens were in fairly good agreement. The patients with the most favorable tumor grade (G I) had significantly better prognosis when the percentage of p53 positive cells was less than 15%. In the group of patients with histologic grade II, the survival was affected by ER expression (more than 30% of positive cells) and p53 levels (less than 15% of positive cells). None of the parameters was predictive in the group of patients with histologic grade III. CONCLUSIONS: We found that determination of immunohistochemical parameters (ER, PR, and p53) on well-differentiated and moderately differentiated endometrial carcinoma of favorable histologic type obtained by curettage enables the recognition of the patients with favorable prognosis, who should not be treated by radical surgery.

Adult↗
PubMed2001

Stabilization of human standing posture using functional neuromuscular stimulation.

Functional neuromuscular stimulation (FNS)/functional electrical stimulation (FES) is a potential way to restore some functionality to the limbs of patients with spinal cord injury through direct/indirect stimulation of the motoneuron. One of the constraints for wider use of FNS on paraplegic patients is the lack of efficient control algorithm. Most of the published works on FNS/FES control are based on oversimplified models of human body dynamics. An innovative control strategy for stabilizing the standing posture of paraplegic patients is proposed here which is a combination of a proportional-plus-derivative controller for motions of the skeletal system and a control action prediction mechanism to produce musculotendon activation. The goal is to produce musculotendon torque which can approximate those demanded by the controller for the skeletal system. In computer simulations, using a detailed skeletal-musculotendon-muscle activation dynamics model of human body, this FNS/FES control approach can stabilize a paraplegic patient's standing posture with the minimum number of musculotendon groups. Also, it is found that this control strategy can maintain stability even in the presence of reasonable variations in the controller's musculotendon parameters.

Computer Simulation↗
PubMed2001

Planar rearrangements of fullerenes.

A notion of planar rearrangement of fullerenes is proposed as a general framework for all conceivable rearrangements of fullerenes satisfying a minimum physicochemical condition. The planar rearrangement is defined as an edge relocation such that the planarity of a given Schlegel diagram remains undisturbed. Graph-theoretical properties of planar rearrangements are discussed and characteristics for establishing a hierarchy between them are pointed out. A number of graph-theoretical concepts have been introduced to provide means for classification and systematic generation of fullerene rearrangements. The simpliest nontrivial rearrangements is shown to be the Stone-Wales rearrangement.

Carbon↗
PubMed1999

Effect of estrogen replacement therapy on cardiac function in postmenopausal women with and without flushes.

Left ventricular heart function and its response to long-term estrogen replacement therapy was assessed in 30 postmenopausal women, 20 of whom had modest to severe hot flushes and 10 of whom had never had them. Continuous transdermal estradiol was given to women who had surgically induced menopause, and a combination of transdermal estradiol and sequential medroxyprogesterone acetate was given to those who had spontaneous menopause. Left ventricular systolic and diastolic function was evaluated by complete two-dimensional M-mode and pulsed Doppler echocardiography before and after 6 and 12 months of therapy. The parameters assessed were: systolic and diastolic blood pressure, heart rate, cardiac septal and posterior wall dimensions, left ventricular end-systolic and end-diastolic dimensions and volumes, ejection fraction (EF), ejection time, peak left ventricular outflow velocity (PFV), flow velocity integral (FVI), acceleration time (AT), mean acceleration of systolic flow (MA), duration of early and late filling phase, peak velocity of the early (E) and late (A) mitral flow, and A/E velocity ratio. Although no difference in chamber and wall dimensions between flushers and non-flushers was found, women with hot flushes had lower (not significantly) EF, PFV, FVI, MA, blood pressure and heart rate before therapy. Twelve-month estrogen replacement therapy significantly reduced cardiac wall dimensions and improved systolic function in both flushers and non-flushers. However, stroke volume, EF and MA were increased whereas systolic blood pressure and heart rate were decreased more in flushers. Also, the increase in E mitral flow and decrease in A/E were more pronounced in flushers. Thus, although estrogen replacement therapy significantly improves heart function in healthy postmenopausal women, there appears to be some minor differences in response between flushers and non-flushers.

Administration, Cutaneous↗
PubMed1998

The effect of hormone replacement therapy on diastolic left ventricular function in hypertensive and normotensive postmenopausal women.

OBJECTIVES: To evaluate the effect of hormone replacement therapy (HRT) on left ventricular diastolic function in a group of hypertensive and normotensive postmenopausal women. METHODS: Left ventricular diastolic function at rest was evaluated by M-mode, two-dimensional and Doppler echocardiography in 19 postmenopausal women with normal blood pressure and 11 postmenopausal women with mild hypertension, before treatment and during 12 months of HRT. Transdermal estradiol was used in women with a surgical menopause and a sequential regimen of transdermal estradiol and peroral medroxyprogesterone acetate in women with a spontaneous menopause. The parameters assessed were: body mass index, heart rate, ejection fraction of the left ventricle (EF), septal (SW) and posterior wall (PW) dimensions, left ventricular end-systolic (LVsd) and end-diastolic (LVdd) dimensions and volumes (ESV, EDV), total diastolic time (DT), duration of the early (Ei) and of the late (Ai) filling phase, peak velocity of the early (E) and late mitral flow (A), A/E velocity ratio and systolic and diastolic blood pressure. Quantitative data were analyzed using unpaired t-test, MANOVA and multiple regression analysis where appropriate. RESULTS: Hypertensive postmenopausal women had significantly higher SW (P < 0.05), PW (P < 0.05), A/E (P < 0.05) and A (P < 0.001) than normotensive postmenopausal women, before therapy. After 12 months of HRT a significant decrease in SW, PW, LVsd, ESV and increase in EF, DT, Ei and E was observed in both hypertensive and normotensive postmenopausal women. Heart rate slowed and systolic pressure decreased significantly only in normotensive postmenopausal women on HRT. CONCLUSION: HRT of 12 months' duration does not deteriorate left ventricular diastolic function of both hypertensive and normotensive postmenopausal women. Improvement in some parameters of diastolic function could be partially explained by the decrease in heart rate and systolic pressure, induced by therapy.

Administration, Cutaneous↗
PubMed1997

A combined Doppler and morphopathological study of ovarian tumors.

OBJECTIVE: To evaluate intratumoral blood flow in 46 patients with ovarian masses. METHODS: Transvaginal color Doppler was carried out in each patient prior to the laparoscopy or laparotomy. Tumors were analyzed according to the size, morphology, presence of the neovascularization, configuration and distribution of the tumoral blood vessels and pattern of the intratumoral blood flow. Vascular patterns of surgically removed tumors were studied microscopically. Three types of vasculature were analyzed: neovascular capillaries without media, sinusoidal thin walled spaces and normal vessels' morphology. The RI (resistance index) values were analyzed in relation to gross appearance, histological type of the tumor, existence of inflammation/necrosis area and vascularization pattern of the tumor. RESULTS: Neovascularization was found in all the malignant tumors with low RI (less than 0.42) and solid or solid cystic gross morphology. Neovascular signals were obtained in only one patient with ovarian endometrioma. Sinusoidal spaces were identified in all the malignant ovarian tumors, but also in most of the benign lesions. Normal vessel morphology was identified in 60% of malignant ovarian tumors and in all the patients with benign ovarian lesions. CONCLUSION: There is a significant correlation between Doppler and histopathological studies in terms of vascularization pattern analysis (detection of neovascular capillaries, sinusoidal spaces and normal vessels morphology). In most of the malignant ovarian tumors there were few areas of vascularization which can be analyzed non-invasively by transvaginal color and pulsed Doppler ultrasound.

Adult↗
PubMed1993

Improvement of lipoprotein lipid composition in type II diabetic patients with concomitant hyperlipoproteinemia by acipimox treatment. Results of a multicenter trial.

OBJECTIVE: To study the tolerability and efficacy of acipimox on hyperlipidemia and diabetes compensation in patients with NIDDM under conditions of a routine clinical practice. RESEARCH DESIGN AND METHODS: We recruited 121 patients (60 men and 61 women) from 10 participating clinical centers. They were randomly divided into two groups and treated for 3 mo either with acipimox (250 mg three times a day) or placebo, using an open study design. RESULTS: Acipimox treatment led to a significant drop in fasting serum total triglyceride levels (by 28%) after 1 mo of drug administration. This decrease prevailed up to the end of the 3-mo study. Serum total cholesterol levels declined by 14%, and high-density lipoprotein tended to rise in acipimox-treated patients. These changes in lipid metabolism were not accompanied by any adverse effects of acipimox on glucose metabolism as judged by HbA1c measurements and the oral glucose tolerance test. Eight patients (out of 82 treated with acipimox) reported moderate adverse events of transient character, such as skin reactions and gastric disturbances. CONCLUSIONS: Acipimox seems to be a useful agent for treatment of diabetic dyslipidemia and does not deteriorate glycemic control.

Blood Glucose↗