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Biomedical subjects

M Kormano

Publications and source records attributed to M Kormano.

213 records · Page 12Linked to original sources
PubMedDate not supplied

Contrast enhancement pharmacokinetics of six ionic and nonionic contrast media.

The contrast enhancement of six contrast media (CM) was compared in 13 tissues of the rat after rapid intravenous bolus injection. The rats were sacrificed at 0 and 40 seconds and 2, 5, and 15 minutes after contrast injection. 125I labeled diatrizoate, metrizamide, ioxaglate, iohexol, iopamidol, and a nonionic dimer, iodecol, were each injected at a dose of 612 mg iodine per kg body weight, and iodine concentration (IC) and contrast enhancement were calculated from radioactivity measurements. Higher blood IC values were obtained with the nonionic CM; similar enhancement patterns were seen in the spleen, heart, lungs, and brain. Renal IC was directly related to the number of iodine atoms per ion or molecule of CM. In consequence, renal IC was inversely related to the CM osmolality, but no such correlation was seen with the blood IC. Metrizamide produced the greatest IC in the organs of the gastrointestinal tract. There was no apparent correlation of IC with molecular structure of physicochemical parameters of the CM in any of the other tissues studied.

Animals↗
PubMedDate not supplied

Different effect of diatrizoate and iopamidol on prostaglandin synthesis in perfused hamster lungs.

The synthesis of prostaglandins and other metabolic products of arachidonic acid (AA) was investigated in isolated perfused lungs of hamsters during the infusion of various concentrations of meglumine diatrizoate and iopamidol. Forty nmol of 14C-AA was infused into the pulmonary circulation with radiographic contrast media (RCM), and prostaglandins, thromboxanes, and metabolites of lipoxygenases were analyzed from the nonrecirculating perfusion effluent. Arachidonate infusion increased the perfusion pressure. This pressor response was decreased by iopamidol but was not changed by diatrizoate. The amount of radioactivity was decreased in the perfusion effluent and increased in lung lipids by iopamidol. Meglumine diatrizoate increased radioactivity in the effluent with minimal effects on the distribution of radioactivity in lung lipids. Almost all arachidonate metabolites were decreased significantly by iopamidol when compared with hypertonic saline whereas diatrizoate caused an increasing trend in the formation of the metabolites of AA. The present study shows that ionic and nonionic RCM have different effects on the metabolism of arachidonic acid.

Animals↗
PubMedDate not supplied

Effect of intravenously administered iodipamide ethyl ester particles on rat liver morphology.

The effect of intravenously injected iodipamide ethyl ester (IDE) particles (150 mgI/kg) on the rat liver was studied by light and electron microscopy. IDE particles were phagocytized by Kupffer cells within a few minutes postinjection. After 4 hours particles began to dissolve in the Kupffer cells causing transient morphologic alterations resembling hydropic degeneration. The number of Kupffer cells seemed, however, to be unchanged and were ultrastructurally normal by 17 days postinjection. Hepatocytes contained large lipid droplets from one to four days after IDE injection. No changes were found in the hepatocytes from one week to one year after IDE injection. The fat-storing cells and endothelial cells remained ultrastructurally normal throughout the study.

Animals↗
PubMedDate not supplied

Modification of platelet aggregation and thromboxane synthesis by intravascular contrast media.

Radiographic contrast media (RCM) decreased significantly platelet aggregation in human platelet-rich plasma (PRP) after addition of arachidonic acid (AA) or adenosine diphosphate (ADP). Unlike hypertonic saline, diatrizoate, ioxaglate, and iopamidol (40 and 160 mM) inhibited AA-induced aggregation. One hundred sixty mM ioxaglate inhibited slightly the concomitant formation of immunoreactive thromboxane B2 (TXB2). The ionic RCM ioxaglate (40 and 160 mM) and diatrizoate (160 mM), but not the nonionic iopamidol, decreased the ADP-induced aggregation more than hypertonic saline. When PRP was incubated with different RCM without any aggregating agents or with ADP, the formation of TXB2 was negligible. Results of this study show that inhibition of AA- and ADP-induced platelet aggregation by RCM is partly due to hypertonicity and partly related to the chemical structure of the RCM molecule. The inhibition of AA-induced aggregation is not caused by the lack of formation of aggregatory TXA2.

Adenosine Diphosphate↗
PubMedDate not supplied

Clinical comparison of Hexabrix, iopamidol, and Urografin-60 in whole body computed tomography.

Urografin 60, iopamidol and Hexabrix were studied in patients undergoing body CT scans to examine the pharmacodynamics of these contrast agents. Immediately following rapid injection, the lower osmolality media, Hexabrix and iopamidol, gave greater aortic concentration of iodine in addition to higher concentrations in the liver and spleen. These two agents also provided significantly better renal enhancement than Urografin 60, with Hexabrix giving higher levels than iopamidol. The higher early vascular concentrations of Hexabrix and iopamidol and the relative absence of side effects due to hyperosmolality and decreased toxicity may have advantages in dynamic CT scanning.

Contrast Media↗
PubMedDate not supplied

Liver perfusion studied with ultrafast CT.

OBJECTIVE: Our goal was to quantify absolute hepatic arterial and portal venous perfusion noninvasively in patients with and without liver disease using ultrafast CT. MATERIALS AND METHODS: A single slice through the porta hepatis was repeatedly scanned after bolus injection of 25 ml of iohexol 300 mg I/ml, followed by a 25 ml saline "chaser" intravenously at 10 ml/s. Thirty-nine controls, 7 cirrhotic patients, and 5 patients with known metastases on the slice plane were studied; hepatic arterial perfusion was determined in 41 patients and portal venous perfusion in 24. Time-attenuation curves from regions of interest drawn over the liver, spleen, aorta, and portal vein were analysed. Hepatic arterial perfusion was calculated by dividing the peak gradient of the liver time-attenuation curve prior to the time of peak splenic attenuation by the peak aortic CT number increase. Splenic perfusion was calculated by dividing the peak gradient of the splenic time-attenuation curve by the peak aortic CT number increase. Portal perfusion was derived by scaling the splenic time-attenuation curve by the ratio of hepatic arterial/splenic perfusion. This scaled curve was subtracted from the liver time-attenuation curve to give a portal curve. The peak up-slope of this curve was divided by the peak rise in splenic or portal vein density. RESULTS: Hepatic arterial perfusion averaged 0.19 ml/min/ml (n = 31) in controls and was raised in cirrhosis to 0.25 ml/min/ml (n = 6) and metastases 0.43 ml/min/ml (n = 4). Portal venous perfusion was 0.93 ml/min/ml (n = 19) in controls and 0.43 ml/min/ml (n = 4) in cirrhosis. Reproducibility has been confirmed. CONCLUSION: Dynamic ultrafast CT shows potential in quantifying arterial and portal hepatic perfusion. The technique may be adaptable to dynamic bolus MRI.

Female↗
PubMedDate not supplied

Cerebral circulation after cardiac arrest. Microangiographic and protein tracer studies.

The effects of ventricular fibrillation and subsequent resuscitation on the microcirculation of the verebral cortex were studied with microangiographic and fluorescent protein tracer techniques. Immediately after revival, a transient period of impaired cerebral perfusion occurred before complete recovery from circulatory arrest was obtained. A circulatory arrest of longer than ten minutes, followed by four to six hours of resuscitation, caused defects of cortical capillary filling in both microangiography and Trypan blue fluorescence. This was considered to represent impairment of cortical perfusion, most likely due to edema. Cardiac arrest up to 12 minutes and subsequent resuscitation per se caused no blood-brain barrier damage. Minimal blood-brain barrier damage occurred in one dog following uncomplicated revival from a 14-minute arrest and in animals with prolonged hypertension post-resuscitation. Up to three consecutive carotid angiographies did not cause blood-brain barrier damage in the postischemic brain.

Angiography↗
PubMedDate not supplied

Effect of hemolysis and clotting on proton relaxation times of blood.

The proton relaxation times T1 and T2 of plasma and clotted blood stored in test tubes were studied at a magnetic field of 0.225 T as a function of time. A satisfactory description of both relaxation processes could be made by two exponential components for the plasma and three components for the clot. The major relaxation component in plasma was the slower one, the T1 of which shortened from about 1 300 ms to about 400 ms between the second and sixth day of storage. The plasma T2 behaved similarly, but shortened less. The shortening of the relaxation time in plasma surrounding the experimental thrombus was concluded to be due to a number of factors, including the release of hemoglobin into plasma, the conversion of hemoglobin to methemoglobin, a concomitant change in the configuration of hemoglobin molecules, and an increased concentration of iron in plasma. The shortening of the relaxation time may also occur in an in vivo hematoma and change the magnetic resonance appearance of a hematoma with time.

Blood Chemical Analysis↗
PubMedDate not supplied

Disc degeneration in young gymnasts. A magnetic resonance imaging study.

Magnetic resonance imaging (MRI) was performed on 35 young competitive gymnasts and 10 control subjects in order to detect the number of degenerated discs and other lumbar spinal disorders. Lumbar radiographs were obtained from all gymnasts who showed evidence of disc abnormality on MRI. Eleven gymnasts had suffered from episodes of low back pain during exercises and eight were found to have evidence of back trauma. Only 3 of the 35 gymnasts had MRI evidence of degenerated discs associated with Scheuermann's manifestations and spondylolysis. Lumbar radiographs confirmed the diagnosis in these three cases. The results indicate that despite the excessive range of motion and strong axial loading of the lumbar spine that are associated with gymnastic maneuvers, incurable primary damage to the intervertebral discs is uncommon in young gymnasts during growth.

Adolescent↗
PubMedDate not supplied

Method dependence of proton spin-lattice relaxation analysis in biologic tissues.

Spin-lattice proton relaxation times (T1) in several biologic and phantom samples have been measured and analysed by using standard inversion recovery (IR) and spin echo (SE) sequences at 0.02 T. The average T1 of the sample was measured with the two-data point method. In the case of bi-exponential relaxation the value of a single T1 is strongly dependent on the TI and TR selected. With short TI the T1 value obtained by using the two point method is approximately equal to the weighted average of the two relaxation time components (T1s and T1l), while at long inversion times TI the single T1 is more dependent on the long component T1l. The more the true short and long relaxation time components T1s and T1l of the bi-exponential relaxation differ from each other, the greater is the potential error, provided that the weights ws and wl do not differ very much. When two-data point analyzing method is used, the possible multi-exponential behaviour of the relaxation in tissues will be missed. For more reliable T1 values a series of images with as many values of TI as possible should be taken. Knowledge of true multi-exponential relaxation parameters helps in optimizing the sequence parameters and the image contrast between the various tissues.

Animals↗
PubMedDate not supplied

A-mode ultrasonic detection of slow flow velocities in vitro.

The lower limits of detection of moving particles was studied with a sensitive A-mode scanner. Particles of two different sizes (25 microns and 90 microns) were perfused with different velocities in two different tubes. The motion of single latex particles with a diameter of 90 microns could be demonstrated in both tubes. The A-mode scanner had no lower limit in detecting motion of the 90 microns particles.

Blood Flow Velocity↗
PubMedDate not supplied

Magnetic resonance imaging of intracranial neoplasms at 0.02 tesla.

Sixty-five patients with single or multiple intracranial neoplasms were examined with an MR imager operating at 0.02 tesla. In 56 patients the diagnosis was histologically confirmed. All patients had an abnormal CT finding. MR images were positive in 59 cases, while the lesion remained undetected or equivocal in 6 cases (2 pituitary adenomas and 4 meningiomas). The MR signal intensity of several meningiomas was equal to that of normal brain tissue. Some astrocytomas were better delineated on MRI than on CT. For the study of pituitary lesions, the spatial resolution was unsatisfactory. The ultralow field MR imager was found to be sensitive for the detection of other intracranial neoplasms.

Adenoma↗
PubMedDate not supplied

Proton T1 relaxation time of normal and abnormal urine.

Relaxation times T1 of normal and abnormal urine samples were measured with a 0.02 tesla MRI device in a spectrometric mode. Protein containing urine from patients with glomerulonephritis showed a slight shortening of T1 relaxation time. Radiographic contrast medium, pH, osmolality or glucose in diabetes did not significantly change the T1 relaxation time of urine. Urine can be used as a T1 relaxation reference in MR imaging of the pelvis even if the patient has received radiographic contrast medium or has diabetes or proteinuria for any reason.

Diatrizoate↗