Biomedical subjects

Tatjana Atanasijevic

Publications and source records attributed to Tatjana Atanasijevic.

6 recordsLinked to original sources

PubMed2006

Calcium-sensitive MRI contrast agents based on superparamagnetic iron oxide nanoparticles and calmodulin.

We describe a family of calcium indicators for magnetic resonance imaging (MRI), formed by combining a powerful iron oxide nanoparticle-based contrast mechanism with the versatile calcium-sensing protein calmodulin and its targets. Calcium-dependent protein-protein interactions drive particle clustering and produce up to 5-fold changes in T2 relaxivity, an indication of the sensors' potency. A variant based on conjugates of wild-type calmodulin and the peptide M13 reports concentration changes near 1 microM Ca(2+), suitable for detection of elevated intracellular calcium levels. The midpoint and cooperativity of the response can be tuned by mutating the protein domains that actuate the sensor. Robust MRI signal changes are achieved even at nanomolar particle concentrations (<1 microM in calmodulin) that are unlikely to buffer calcium levels. When combined with technologies for cellular delivery of nanoparticulate agents, these sensors and their derivatives may be useful for functional molecular imaging of biological signaling networks in live, opaque specimens.

Animals↗

PubMed2006

Dynamic imaging with MRI contrast agents: quantitative considerations.

Time-resolved MRI has had enormous impact in cognitive science and may become a significant tool in basic biological research with the application of new molecular imaging agents. In this paper, we examine the temporal characteristics of MRI contrast agents that could be used in dynamic studies. We consider "smart" T1 contrast agents, T2 agents based on reversible aggregation of superparamagnetic nanoparticles and sensors that produce changes in saturation transfer effects (chemical exchange saturation transfer, CEST). We discuss response properties of several agents with reference to available experimental data, and we develop a new theoretical model that predicts the response rates and relaxivity changes of aggregation-based sensors. We also perform calculations to define the extent to which constraints on temporal resolution are imposed by the imaging methods themselves. Our analysis confirms that some small T1 agents may be compatible with MRI temporal resolution on the order of 100 ms. Nanoparticle aggregation T2 sensors are applicable at much lower concentrations, but are likely to respond on a single second or slower timescale. CEST agents work at high concentrations and temporal resolutions of 1-10 s, limited by a requirement for long presaturation periods in the MRI pulse sequence.

Brain Mapping↗

PubMed2006

Mechanisms of aortic blunt rupture in fatally injured front-seat passengers in frontal car collisions: an autopsy study.

We tried to explain the mechanisms of the aortic blunt ruptures in fatally injured drivers and front passengers, unrestrained by seatbelts, by analyzing the frequencies of both aortic ruptures and concomitant injuries to 12 organs and body regions. The sample consisted of 393 subjects: 251 drivers and 142 front passengers (325 male and 68 female passengers, the mean age 41.0 +/- 15.5). The total number of the complete blunt aortic ruptures in the sample was 116 (80 in the drivers and 36 in the front passengers). The weakest part of the aorta seems to be the isthmus (47 isthmus ruptures in the drivers and 27 in the front passengers). The statistically significant concomitant injured organs and body regions with the aortic ruptures were the liver, the sternum, and the diaphragm in the car drivers and the head and the neck in the front passengers. According to these results, the mechanisms of thoracic aorta rupture are different for fatally injured drivers and front passengers. For car drivers, they are associated and simultaneous with both thoracic and abdominal compression due to deceleration of the body at the moment when the driver's body slides forward and flexes across and against the steering wheel. For the front passengers, the mechanism is the caudorostral hyperextension of the thoracic aorta at the moment when the body is stopped by a dashboard, but the head continues forward with great velocity: the carotid vessels pull the aortic arch forward at the same time as the intercostal arteries fix the thoracic part of the aorta and pull it downwards.

Accidents, Traffic↗

PubMed2004

Amount of postmortem bleeding: an experimental autopsy study.

An experimental autopsy study was performed on 64 cases (55 male, 9 female; average age 51.5 +/- 16.2 years) of sudden natural (38 cases) and asphyxic deaths (26 cases). The study objective was the amount of postmortem bleeding from postmortem cutting of the thoracic aorta, related to the time since death. The amount of postmortem bleeding ranged from 100 to 1300 cm, 440.6 +/- 268.1 cm on average. The time since death up to the autopsy time ranged from 4 to 72 hours, 19.4 +/- 12.9 in average. A statistically significant correlation between the amount of postmortem bleeding and postmortem time interval was stated: Pearson correlation test value r = -0.461 (P = 0.000): the shorter the time interval, the larger the amount of bleeding. The formula of linear regression was estimated according to this correlation: amount of postmortem bleeding (cm) = -9.571 x time since death (h) + 626.659. This proves that the amount of postmortem bleeding (eg, from aortic blunt rupture) could be about 620 cm.

Adolescent↗

PubMed2003

Medicolegal diagnostic value and clinical significance of traumatic incomplete tears of the basilar artery.

Ruptures of arteries of the vertebrobasilary system are relatively frequent in medicolegal practice, and their origin may be both natural and violent. Tears that affects the whole thickness of the basilar artery cause subarachnoid hemorrhage (SAH), with an often rapid fatal outcome. 1-3 However, in some situations, arterial tears may be incomplete, involving the intima or both the intima and the media, but with preserved adventitia. 1, 4 Although such incomplete tears are not the source of immediate subarachnoid bleeding, their presence may be important from both a medicolegal and a clinical point of view. The aim of this article is to point out the significance of incomplete tears of basilar artery as a possible diagnostic sign of traumatic origin of SAH as well as a certain mechanism of injury, which involves forcible hyperextension and rotational movements of the head. The authors also describe their method of performing longitudinal section of the basilar artery, both at autopsy and for histologic examination, which is convenient for identifying multiple transversal incomplete tears of this blood vessel. The article is based on the analysis of three cases from the autopsy material of the Institute of Forensic Medicine in Belgrade.

Accidents, Traffic↗

PubMed2003

Analysis of neck injuries in hanging.

Retrospective study of suicidal hangings was made on 175 cases (133 male victims, 42 female victims) for a 5-year period. The mean age was 47.33 +/- 17.51 years. The sample was divided in 4 groups according to the position of the ligature knot (anterior, right, left, and posterior hanging). The authors analyzed all visible injuries of soft tissues and bones and cartilage of the neck, and in 150 cases (85.7%), we established that there was at least one injury of these structures (hematoma or fracture for example). The most frequent injury was to sternocleidomastoid muscles. Fracture of throat skeleton was detected in 119 cases (68%). The proportion of fractures increases with age of the deceased. There was no clear correlation between frequency of neck injuries and type of hanging.

Adolescent↗