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Biomedical subjects

Dragan Mihailovic

Publications and source records attributed to Dragan Mihailovic.

6 recordsLinked to original sources
PubMed2006

Possible interactions of genetic and immuno-neuro-endocrine regulatory mechanisms in pathogenesis of congenital anomalies.

The process of organogenesis depends on genetic and environmental factors. Besides genetic background, congenital anomalies can also be influenced by micro environmental changes, which are related to maternal-foetal interactions followed by the production of cytokines, hormones, neurotransmitters, growth factors and biochemical mediators, and stress proteins. Pre-natal maternal stress, including infections, psychological stress and other teratogens, can influence a disregulation of maternal immune, endocrine and nervous systems, during pregnancy. This is a crucial condition for the abnormal growth and development of the foetus. Activated maternal immune system can alter the cytokine network and make it inadequate for normal embryogenesis and organogenesis. Heat-shock proteins play an important role in stress physiology repairing DNA errors or activating pro-inflammatory response. Regarded from this aspect, the altered cytokine network suggests aetiopathogenetic basis of congenital anomalies in neonates. It is our wish to point out our potentially harmful conditions in the development of congenital anomalies, as well as their control by using pre-natal and pre-conceptional diagnostics and treatment.

Animals↗
PubMed2005

Solubility of Mo6S4.5I4.5 nanowires in common solvents: a sedimentation study.

Due to their ease of fabrication and monodisperse, metallic nature, molybdenum-sulfur-iodine nanowires are an interesting alternative to carbon nanotubes for some applications. However very little is known about the solubility of these materials. In this work we have investigated the solubility of Mo(6)S(4.5)I(4.5) nanowire soot in a range of common solvents by performing sedimentation studies and microscopic and spectroscopic characterization. A sedimentation equation was derived showing that the concentration of any insoluble dispersed phase decreases exponentially with time. We find that in all solvents, Mo(6)S(4.5)I(4.5) nanowire soot contains three phases, two of which are insoluble with one stable phase. Microscopy and spectroscopy show that the first insoluble phase is associated mainly with spherical impurities and sediments rapidly out of solution resulting in purification. The second phase appears to consist of insoluble nanowire bundles and sediments more slowly, eventually leaving a stable dispersion of nanowire bundles. The stably dispersed bundles tend to be smaller than their insoluble counterparts. The best solvents studied were 2-propanol and dimethylformamide. Microscopy studies showed that, in the case of 2-propanol, sonication significantly reduced the bundle size relative to the unsonicated bulk. However, during sedimentation, large quantities of bundles were observed to reaggregate to form larger bundles which subsequently sedimented out of solution. In general, the sedimentation properties of the various phases did not vary significantly with concentration indicating that the insoluble nanowires are intrinsically insoluble. However, the diameter of the stably dispersed bundles decreased with concentration, until very small bundles consisting of only two or three nanowires were observed at concentrations below 0.003 mg/mL. In addition, stable composite dispersions were produced by mixing the nanowires with poly(vinylpyrrolidone) in 2-propanol opening the way for the formation of polymer/inorganic nanowire composites.

Journal Article↗
PubMed2004

Hole interactions with molecular vibrations on DNA.

We report on a study of the interactions between holes and molecular vibrations on dry DNA using photoinduced infrared absorption spectroscopy. Laser photoexcited holes are found to have a room-temperature lifetime in excess of tau > 1 ms, clearly indicating the presence of localization. However, from a quantitative model analysis of the frequency shifts of vibrational modes caused by the holes, we find the hole-vibrational coupling constant to be relatively small, lambda approximately 0.2. This interaction leads to a change in the conformational energy of DeltaE0 approximately 0.015 eV, which is too small to cause self-trapping at room temperature. We conclude that, at least in the dry (A) form, DNA is best understood in terms of a double chain of coupled quantum dots arising from the pseudorandom chain sequence of base pairs, in which Anderson localization prevents the formation of a metallic state.

DNA↗
PubMed2003

Nuclear volume and total optical density in Down syndrome.

OBJECTIVE: To estimate nuclear size and integrated optical density of parenchymal cells from various organs in patients with Down syndrome and a control group. STUDY DESIGN: During the years 1988-2000, 14 cases of Down syndrome were found (8 male and 6 female). Ten infants without congenital anomalies died of respiratory distress syndrome and were used as a control group. Five nuclear variables were estimated: area, equivalent diameter, volume of equivalent sphere, roundness and total optical density (TOD). RESULTS: Mean nuclear volume and TOD of thyroid follicular cells were significantly lower in patients with Down syndrome (43.82 +/- 8.95 and 173.81 +/- 32.85 microns 3, respectively) than in the control group (65.46 +/- 15.31 and 234.58 +/- 32.85 microns 3, respectively) (P < .01). Mean hepatocite nuclear volume and TOD were significantly higher in the control group (165.54 +/- 55.42 and 220.84 +/- 51.75 microns 3, respectively) than in trisomy 21 (110.39 +/- 32.97 and 176.58 +/- 28.53 microns 3, respectively) (P < .05). CONCLUSION: The present results suggest altered gene expression in excessive genetic material, especially in thyroid follicular cells.

Case-Control Studies↗
PubMed2002

Discriminant analysis of image karyometric variables in benign and malignant melanocytic skin lesions.

OBJECTIVE: To perform a quantitative analysis to identify which of 7 nuclear morphometry-related variables are of diagnostic value in distinguishing benign from malignant melanocytic skin lesions. STUDY DESIGN: At the Institute of Pathology, University of Nis, formalin-fixed, paraffin-embedded skin biopsies from 23 cases of benign nevi (18 intradermal and 5 junctional) and 25 cases of primary nodular malignant melanomas were retrieved. Specimens were routinely stained with hematoxylin and eosin and analyzed using a computer-assisted interactive image analysis system. Nuclear area, equivalent diameter, volume of equivalent sphere, perimeter, mean chord, circularity and integrated optical density were estimated after manual editing of binary images. RESULTS: In univariate analysis, 6 features were found to be significantly different between the benign and malignant groups (P < .0001); all measured nuclear variables (except circularity) were higher in malignant melanomas. No significant differences were found among lesions with respect to nuclear shape. Using discriminant function analysis, a correct diagnosis was achieved in 95.8% of benign nevi cases and 84.0% of malignant melanoma cases. The best discriminant variable was nuclear area. CONCLUSION: Image analysis is diagnostically relevant to the evaluation of melanocytic lesions of the skin. The area of the nucleus appeared to have potential for differentiating benign from malignant tumors and can be estimated in the course of routine histology.

Cell Nucleus↗