Precipitation behavior in a medium carbon,ti-v-n microalloyed steel

The precipitation behavior of a medium carbon steel microalloyed with Ti, V, and N has been studied by analytical transmission electron microscopy in the as-cast and isothermally heat-treated states, as well as at different stages in the thermomechanical processing of the steel. Mixed (Ti,V) nitrides were found in all the structures, but there was no evidence for mixed carbonitride formation. The Hillert-Staffansson model was used to predict the composition of the nitrides as a function of tem-perature. Upon prolonged aging many of the precipitates became “fragmented” and were no longer single crystals. At the same time, the volume fraction of precipitates dropped, while their average Ti content increased. Possible explanations for this unexpected behavior are discussed in this article.     

Orbitography with a new non-ionizing water-soluble contrast medium

Metrizamide is a non-ionic water-soluble contrast medium which is isotonic with human blood and tissue fluid at a concentration of 170 mgI/ml. Retrobulbar injection of 3 ml isotonic metrizamide in the muscular conus of rabbits causes slight and inconstant cellulitis, but a similar reaction can also be found after injection of the same amount of saline. It seems probable that the introduction of fluid sufficient to cause an increase in the retrobulbar pressure can cause inflammatory changes in the orbital tissue, and that this is not always caused by the contrast medium itself. Four patients were examined by orbitography with injection of 4 ml isotonic metrizamide. There were no side effects, and the orbitograms showed contrast of good quality. Metrizamide is therefore considered very suitable for orbitography, especially in hospitals where computer-tomography is not yet available.     

Adverse effects of a new non-ionic contrast medium in heart catheterization

Tolerance of a New Non-ionic Contrast Medium during Heart Catheterization The new non-ionic contrast medium iomeprol (CAS 78649-41-9) was investigated for adverse reactions and diagnostic quality in 75 patients undergoing heart catheterization. Blood pressure and ECG were continuously registered. The patients were asked for subjective complaints by using a standardized questionnaire. Experienced cardiologists assessed the diagnostic quality of the angiograms. With iomeprol neither fatal nor severe reactions were observed. The dye had only little influence on diastolic and systolic blood pressure; heart rate was not significantly influenced. Minor and partly moderate adverse reactions all being completely reversible were observed in 14 patients (18.7%). One patient complained of strong heat sensation after dye injection into the left ventricle. The diagnostic quality of the angiograms allowed to make a definitive diagnosis in all cases. Thus, iomeprol proved to be a suitable and safe contrast medium for heart catheterization.     

Delayed-type hypersensitivity to a nonionic, radiopaque contrast medium

BACKGROUND: True allergic reactions to iodinated radiocontrast media are rare, and only a few well-documented cases of delayed-type hypersensitivity reactions caused by contrast media have been described. METHODS: We report a 61-year-old patient in whom percutaneous transluminal coronary angioplasty (PTCA) was performed with iopamidol, a nonionic contrast medium. Seven days later, the patient developed generalized maculopapular exanthema. Repeated patch tests with several iodinated agents were performed. RESULTS: A first patch test with iopamidol was positive. Repetition of the patch tests showed positive results to iopamidol as well as to iohexol and ioversol, two other nonionic contrast media, but not to other iodinated substances. Three months later, PTCA was repeated, and iopamidol was used again. Despite premedication, pruritic macular exanthema developed 1 day later. Whether iopamidol or trometamol -- an additive substance in the contrast medium -- was causative could not be determined, since a third set of patch tests was negative. CONCLUSIONS: Delayed-type hypersensitivity reactions to iodinated contrast media are rare. We recommend that patients with delayed exanthematous reactions undergo patch or intradermal tests with different contrast media and their additives, and that readings be performed immediately and later at days 2 and 3.     

The effect of uropolinum, a diatrizoate contrast medium, on erythrocyte metabolism

In the presence of Uropolinum (sodium and N-methylglucamine diatrizoate) the lactate production of erythrocytes was decreased in half of the cases studied. The addition of albumin showed a protective effect on glycolysis of red blood cells. A decrease in glutathione reductase and increase in glucose-6-phosphate dehydrogenase activity was observed in all cases. Acethylcholinesterase activity was unaffected by Uropolinum. The activities of phosphohexose isomerase, phosphofructokinase. aldolase and ATP-ase were decreased in some subjects and increased in the others. It may be attributed to individual sensitivity of some subjects to diatrizoates and is consistent with clinical observations.     

Precipitation of VC in ferrite and pearlite during direct transformation of a medium carbon microalloyed steel

Transmission electron microscopy of an air-cooled medium carbon (0.5 wt pct) steel containing 0.1 wt pct vanadium has shown that VC precipitates by the interphase mecha-nism during transformation to both proeutectoid and pearlitic ferrite. Depending upon the rate of transformation, a considerable proportion of the available vanadium may remain in supersaturated solid solution and can be precipitated as VC upon subsequent aging at 700°C. It was found that the proportion of proeutectoid ferrite, the interlamellae pearlite spac-ings and the VC precipitate dispersion parameters all decreased with increasing cooling rate in as-transformed material. G. FRIMODIG were formerly undergraduate students     

Gd-DTPA: an alternative contrast medium for CT

OBJECTIVE: The purpose of this study was to demonstrate that gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) could be used as a contrast medium in CT as an alternative to iodine-based compounds. MATERIALS AND METHODS: Solutions of different concentrations of Gd-DTPA and iopromide were scanned in a tissue equivalent phantom and it was shown that Gd-DTPA caused 2.5 times the attenuation of an equimolar solution of iopromide. From these in vitro studies an in vivo dose of 0.5 mmol/kg Gd-DTPA was calculated to be equivalent to 50 ml iopromide 300. RESULTS: Pre- and postenhancement CT was performed in a volunteer using Gd-DTPA intravenously, and adequate enhancement occurred in intracranial vessels. CONCLUSION: Gd-DTPA can be used to provide enhancement during CT and might be of value in iodine-sensitive patients.     

Effect of contrast medium on corpus cavernosum smooth muscle

OBJECTIVE: To study the molecular basis of complete androgen insensitivity syndrome (AIS). STUDY DESIGN: The coding region of the human androgen receptor (hAR) gene in two women with AIS was amplified with polymerase chain reaction using 12 pairs of oligonucleotide primers and then sequenced with a dye terminator method. RESULTS: Both patients had mutation in exon E of the androgen-binding domain. In one patient, codon 732 GAC (aspartic acid) was changed to ACC (asparagine), and her CAG polyglutamine tract had 27 repeats. In the other patient, codon 765 GCC (alanine) was changed to ACC (threonine), and her CAG polyglutamine tract in exon A had 19 repeats. CONCLUSION: Except for CAG polyglutamine polymorphism, these two missense mutations were the only differences detected in the coding region of the hAR gene. Both mutations involved the CpG sequence, which has been regarded as a mutation hotspot. To the best of our knowledge, these two mutations have not been observed before in Chinese women. Elucidation of the molecular defects of AIS patients would be very helpful for genetic counseling and prenatal diagnosis.     

Indications for contrast medium administration in MR-angiography of cerebral blood vessels

Time-of-flight MR-angiography of large volumes is limited by the occurrence of saturation effects, which lead to low signal in both veins and arteries. Alternatively to a number of other MRA-techniques, intravenous application of paramagnetic contrast media in combination with 3D-pulse sequences with or without flow refocussing allows the depiction of slow vessels in large volumes without technical extra expenses. The main intracranial indication is anatomical 3D-imaging of normal and dysplastic cerebral veins with high spatial resolution, and the additional depiction of the venous drainage in AVMs, when unenhanced MRA shows only the arteriel supply and the nidus. In large cerebral aneurysms, bridging veins and venous sinuses, partial thromboses can easily be differentiated from slow flow. Contrast-enhancing tumors can be depicted together with normal or displaced vessels. Improvements of arterial signal due to contrast media with currently used routine MRA techniques are clinically not significant. Signal loss due to spin dephasing in vessels with complex flow is not influences by contrast media. Results of contrast-enhanced MRA are determined by the timing of injection. Since arteries and veins are both imaged with high signal intensity, improvements of postprocessing procedures for secondary vessel segmentation are necessary.     

Safe amounts of contrast medium for angiocardiography in neonates and infants

The results were analysed of 485 (biplane) cineangiocardiograms performed in 200 consecutive cardiac investigations on neonates (under 4 wk) and infants (4 wk to 1 yr). 10 deaths occurred during or within 24 h of cardiac catheterization, all in patients who were profoundly acidemic because of their hemodynamic disturbance. A total dose of Cardio-Conray at any one investigation of 4-5 ml/kg body weight was satisfactory and without undue risk. Single injections of 1.5-2.0 ml/kg body weight were safe whilst providing optimal diagnostic information. The interval between multiple injections did not appear to affect the risk to the patients.     

Myelography in the dog with non-ionic contrast media at different iodine concentrations

Image quality and side effects were evaluated retrospectively in a series of 183 myelographic studies performed with two non-ionic contrast media (iohexol and iopamidol) at different concentrations. Side effects during and following the procedure were recorded. Image quality was assessed using an arbitrary scoring system and statistical analysis was performed with the cross-tabulation test (4 x 2 table) by comparing two groups receiving contrast medium at higher and lower concentrations. No significant differences in side effects were observed between the two groups but the ratings for image quality were significantly higher in the group receiving contrast medium at the higher concentration than in the group receiving the lower concentration. The results suggest that a high concentration of non-ionic contrast media can safely be used in dogs and may improve image quality.     

Pulmonary hypertension. Response of vasoactive peptides to a nonionic contrast medium in patients undergoing pulmonary angiography

A 46-years-old male was admitted to our hospital because of productive cough and infiltrates on the chest roentogenogram. The patient had a history of left upper bullectomy ten years prior to the admission. The CT scan of the chest on admission showed infiltrats with cavitation in the left apex and multiple bullae in almost whole lung. Microscopical examination of smears of sputum and bronchoalveolar lavage fluid revealed acid-fast bacilli. They were identified as Mycobacterium szulgai by DNA-DNA hybridization method. The patient was treated with isoniazid, streptomycin and rifampicin. After treatment for about a month, the culture of sputum converted to negative for M. szulgai. After about three months hospitalization, the infiltrates decreased and the cavity wall became thin, and no recurrence sign has been observed after the discharge. There are a few case reports of pulmonary infection due to M. szulgai associated with bullous disease of the lung in Japan.     

MRT of experimental liver abscesses: a comparison of a new blood pool contrast medium with gadolinium-DTPA in animal experiments

PURPOSE: In an experimental pyogenic liver abscess model, the signal intensities were compared intraindividually and interindividually after the application of a new blood pool contrast agent, 24-gadolinium-DTPA (diethylenetriamine-pentaacetic acid) cascade polymer, and after the application of gadopentetate dimeglumine. METHODS: In 20 rabbits with experimentally induced liver abscesses, the relative signal intensities of the liver, abscess centre, abscess wall and portal vein were assessed before and between 30 seconds and 60 minutes after injection of a 25 mumol/kg dose of gadolinium polymer and of 100 mumol/kg of gadolinium-DTPA, respectively. Measurements were performed at 1.5 Tesla, using a head coil and a Flash-2-D sequence. RESULTS: The interindividual comparison (unpaired T-test, p < 0.05) yielded significant differences of the relative signal intensities of the abscess centre (at any time point after contrast-media application), abscess wall (between 15 and 60 minutes after contrast media application), and portal vein (between 30 seconds and 7.5 minutes after contrast media application). The interindividual comparison showed a significantly higher abscess centre-liver contrast (between 30 seconds and 12.5 minutes after contrast media application) and a significantly higher abscess wall-centre contrast (between two and 7.5 minutes after contrast media application) after the application of gadolinium polymer compared with gadopentetate dimeglumine. CONCLUSION: In this animal model, the higher abscess centre-liver contrast after the application of gadolinium polymer was the basis for a better and prolonged visibility of the abscesses, as compared with images acquired after injection of gadopentetate dimeglumine.     

Must the patient fast before intravascular injection of a non-ionic contrast medium? Results of a controlled study

PURPOSE: Prospective evaluation of food and fluid restriction before the intravascular injection of a non-ionic contrast medium. MATERIAL AND METHODS: 1000 patients (657 men, 343 women; average age 59 +/- 1/4 5 years) undergoing intravascular contrast injections (CT, phlebography, angiography, urography) were randomly allocated to two groups. Group A had no fluid or solids for at least four hours before the injection (499 cases); group B were allowed unlimited food and fluid (501 cases). Both groups were comparable in all other respects and all were given the non-ionic contrast medium iopamidol (300 mg l/ml). RESULTS: The incidence of acute complications was 3.5%. There was, however, no statistically significant difference between the two groups (p = 0.29). Late adverse reactions were seen in 3.9% patients. There was again no difference between the two groups (p = 0.33). No serious or life threatening complications occurred. CONCLUSION: Restriction of food and fluid before intravascular injection of contrast medium does not reduce the number of adverse side effects. For reasons of patient comfort and compliance, and to achieve adequate hydration, the patient should not fast before injection of contrast.     

Magnetic resonance imaging of the galactosemic dog eye using magnetization transfer contrast

Magnetization transfer contrast (MTC) enhanced magnetic resonance (MR) imaging is a technique that generates high contrast images based on characteristic tissue differences resulting from the interaction of water and macromolecules. In this study, the feasibility of applying this technique to documenting the progression of osmotic sugar cataract formation was investigated in male beagles, initially 6 or 24 month old, fed a diet containing 30% galactose. MTC enhanced magnetic resonance imaging was periodically conducted on these animal's eyes at 2-Tesla. The lens MR images were compared to photographs obtained by photo-slit lamp and retroillumination photography. The MTC technique provided improved image details of the lens and anterior segment that documented osmotic changes from initial cortical vacuole formation to cortical and nuclear changes associated with advanced sugar cataracts. The latter could not be observed by photo-slit lamp or retroillumination photography.     

Experimental evaluation of tube potential and contrast medium concentration for cholangiography

Antitussive activity and some other related pharmacological properties of d-3-methyl-N-methylmorphinan were studied. Toxic symptoms in mice and dogs were due to the CNS excitation. Acute toxicity of (AT-17) in mice was slightly (s.c.) or far (p.o.) weaker than that of codeine, but it was three times as toxic as codeine in dogs (i.v.). Antitussive efficacy was about 40% of that of codeine in dogs, whereas 77% as potent as codeine in cats. It showed no relaxing effect on the bronchial muscle of guinea pigs in either normal tone or histamine-induced spasms. It had analgesic effect 1/3 as potent as codeine in mice but it was not antagonized by levallorphan. The prolongation of hexobarbital sleeping time by AT-17 was similar extent to that by codeine. Anti-electroshock effect was half as potent as that of phenobarbital. The inhibitory effect on the transportation of intestinal contents in mice was far weaker than that of codeine. Effect on the respiratory and circulatory systems were also investigated.