Dynamics of oxygen tension in the tissues of patients with post-thrombophlebitic syndrome

With the use of the methods of percutaneous contact polarography, roentgeno-contrast phlebography, Doppler ultrasound, 83 patients with different location and stage of the post-thrombophlebitic syndrome were examined. The significant alteration of the indices of polarographic curve versus the norm was defined. The most pronounced disorders were revealed in occlusion of the deep veins of the lower extremities.     

Lead absorption and excretion in rats given insoluble salts of pectin and alginate

Exposure to environmental lead remains a widespread problem in most industrialized countries. Usage of modern agents purposed for elimination of heavy metals as well as for therapy and prevention of chronic poisoning does frequently result in toxic signs. Dietary nonstarch polysaccharides were suggested to be effective when used for this purpose. The present study was conducted to estimate metal binding capacity and effects of calcium salts of pectate and alginate on lead absorption, distribution, and removal with feces. Under in vitro conditions calcium alginate showed the highest lead-binding capacity in comparison with other agents studied. Metal binding capacity of calcium pectate was slightly lower. In rats simultaneous administration of lead acetate and suspensions containing calcium alginate or calcium pectate prevented metal absorption and significantly reduced lead accumulation in inner organs and femur. In experiments estimating lead removal from inner organs and femur in rats preliminary exposed to the heavy metal, calcium alginate and calcium pectate were the most effective agents studied in comparison with others, as indicated by reduced lead concentration in organs and femur as well as increased metal content in feces of laboratory animals. The results suggest that calcium pectate and calcium alginate may be considered perspective dietary compounds purposed for prevention and treatment of chronic lead poisoning.     

Three‐dimensional MR‐encephalography: Fast volumetric brain imaging using rosette trajectories

MR‐Encephalography (MREG) is a technique that allows real time observation of functional changes in the brain that appears within 100 msec. The high sampling rate is achieved at the cost of some spatial resolution. The article describes a novel imaging method for fast three‐dimensional‐MR‐encephalography whole brain coverage based on rosette trajectories and the use of multiple small receiver coils. The technique allows the observation of changes in brain physiology at very high temporal resolution. A highly undersampled three‐dimensional rosette trajectory is chosen, to perform single shot acquisition of k‐space data within 23 msec. By using a 32‐channel head coil array and regularized nonuniform Fourier transformation reconstruction, the spatial resolution is sufficient to detect even subtle centers of activation (e.g. human MT+). The method was applied to visual block design paradigms and compared with echo planar imaging‐based functional MRI. As a proof‐of‐principle of the method's ability to detect local differences in the hemodynamic response functions, the analyzed MR‐encephalography data revealed a spatially dependent delay of the arrival of the blood oxygenation level dependent response within the visual cortex. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Three‐dimensional mapping of the B1 field using an optimized phase‐based method: Application to hyperpolarized 3He in lungs

A novel method is presented for the three‐dimensional mapping of the B₁‐field of a transmit radio‐frequency MR coil. The method is based on the acquisition of phase images, where the effective flip angle is encoded in the phase of the nonselective hard pulse excitation. The method involves the application of a rectangular composite pulse as excitation in a three‐dimensional gradient recall echo to produce measurable phase angle variation. However, such a pulse may significantly increase the radio‐frequency power deposition in excess of the standard acceptable SAR limits, imposing extremely long TRs (>100 msec), which would result in acquisition times significantly greater than a single breath‐hold. In this study, the phases of the radio‐frequency excitation are modified, resulting in a different pulse sequence scheme. It is shown that the new method increases sensitivity with respect to radio‐frequency inhomogeneities by up to 10 times, and reduces the total duration of the pulse so that three‐dimensional B₁ mapping is possible with ³He in lungs within a single breath‐hold. Computer simulations demonstrate the increase in sensitivity. Phantom results with ¹H MRI are used for validation. In vivo results are presented with hyperpolarized ³He in human lungs at 1.5T. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Combined prospective and retrospective motion correction to relax navigator requirements

Prospective motion correction can prevent motion artifacts in magnetic resonance imaging of the brain. However, for high‐resolution imaging, the technique relies on precise tracking of head motion. This precision is often limited by tracking noise, which leads to residual errors in the prospectively‐corrected k‐space data and artifacts in the image. This work shows that it is possible to estimate these tracking errors, and hence the true k‐space sample locations, by applying a two‐sided filter to the tracking data after imaging. A conjugate gradient reconstruction is compared to gridding as a means of using this information to retrospectively correct for the effects of the residual errors. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Variations in hemodynamic parameters and ECG in healthy, conscious, freely moving telemetrized beagle dogs

Interpretation of the dynamic cardiovascular parameters on safety pharmacology studies is a challenging process; sometimes, it is difficult to separate normal physiological variations from the effects of the test drug. Data from healthy control Beagle dogs (41 males and 25 females) implanted with telemetry transmitters (DSI, St. Paul, MN) from 34 studies performed from 2003 to 2005 were analyzed. Telementry data were collected for a 30-s period every 10 min for 24 h after sham dosing. One-hour averages were analyzed. Prior to dosing, heart rate (HR) was 95.6±26.6 bpm; mean systolic, and diastolic blood pressure (BP) were 105.3±12.7, 142.5±5.3, and 84.7±11.1 mmHg, respectively. PR, QRS, QT, and corrected (Van de Water) QT intervals were 121±13, 33±3, 217±23, and 245±18 ms, respectively. Seasonal and slight diurnal patterns were noticed only in HR; BP and body temperature were more stable. PR and QT intervals were inversely related to HR; in addition, the duration of PR was influenced by the light cycle. A comparison of three QT correction formulas demonstrated that Van de Water's formula provided the optimal results in Beagle dogs over a wide range of HR.