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PubMed1992

Magnetization transfer contrast (MTC) imaging of skeletal muscle at 0.26 Tesla--changes in signal intensity following exercise.

Magnetization transfer contrast (MTC) imaging of skeletal muscle before and after exercise has been studied in normal volunteers at 0.26 Tesla. A saturation pulse was applied over a range of offset frequencies immediately before a gradient recall echo sequence. Substantial signal loss was observed in all muscles. After exercise, selective saturation resulted in a significant increase of contrast between active and less active muscle, a phenomenon attributable to an increase in extracellular water content. MTC imaging provides a more sensitive method to detect changes in water distribution in human skeletal muscle.

Adipose Tissue↗
PubMed1991

[A case of bilateral multiple pulmonary arteriovenous fistula treated by the right fistula plication and resection of the left lingual lobe with use of microwave tissue coagulator (MTC)].

A 53-year-old man with the history of brain abscess and multiple cerebral arterio-venous malformations underwent the staged operation for bilateral multiple pulmonary arterio-venous fistulas (PAVF). Right fistula plication and the resection of the left lingular lobe using MTC were performed through posterolateral thoracotomy. Postoperatively, the patient showed the right residual fistula, but, he has been doing well without PAVF complications such as polycythemia and hypoxemia. In conclusion, 1) PAVF with central nervous system complications should be treated aggressively either by surgery or by embolization. 2) MTC was useful for the resection of the lung because of no air leak and bleeding coming from the resected section.

Arteriovenous Fistula↗
PubMed1990

Long-term survival in sporadic and familial medullary thyroid carcinoma with special reference to clinical characteristics as prognostic factors. The Swedish MTC Study Group.

All the 249 patients with medullary thyroid carcinoma (MTC) diagnosed during a 23-year period in Sweden were followed up completely for 4-27 years. The overall relative survival was 79.9% at 5 years after diagnosis and 68.6% at 10 years. After 5 years of follow-up, the relative survival rate was 5 percentage points higher in females than in males; 30 percentage points higher in patients aged less than 40 than in those 60-69 years at diagnosis; 24 percentage points higher in patients with familial disease detected at screening than in those with sporadic MTC; 20, 26 and 48 percentage points lower in patients with stage II, III, and IV, respectively, than in those with stage I; and almost 30 percentage points lower in the group of patients with a large tumor (greater than 3 cm) than in the group with a small one (less than 1 cm). In multivariate proportional hazards analyses of all these important determinants of outcome, the prognostic information provided by age and stage was still significant when several morphologic characteristics were taken into account (nuclear DNA content, calcitonin immunoreactivity, amyloid content, argyrophil reaction and state of the tumor capsule).

Adolescent↗
PubMed1989

Right colonic hemangioma diagnosed by scintigraphy with 99-mTc sucralfate. A case report.

99-mTc-SF gastrointestinal scintigraphy used in recent years in the assessment of site and activity for ulcerative lesions, was shown to be very important for the diagnosis of a rare case of right colonic hemangioma. A young female patient suffering for some time from functional intestinal disorders, following negative radiologic and endoscopic findings, underwent 99-mTc-SF scintigraphy, which showed massive uptake of radioactivity in the ascending and right flexure of colon. A repeated colonoscopy with biopsy allowed the histologic diagnosis of capillary hemangioma.

Adult↗
PubMed1987

[Pulmonary resection by microwave tissue coagulator (MTC)--clinical application].

A 55 year old male with metastatic lung and liver cancer was subjected to pulmonary and hepatic resections using Microwave Tissue Coagulator (MTC). No adverse effects were observed in this patient after operation. The resected specimen of the lung had the bronchioli partially accompanied with cartilages. Coagulation for the bronchioli of at least lmm in size, by MTC, could be carried out resulting in no air leakage after operation.

Adenocarcinoma↗
PubMed1999

Evaluation of liver diseases via MTC and contrast agent.

Our goal was to characterize pathological tissues of liver by magnetic resonance (MR)-related parameters such as T1 and magnetization transfer (MT) indices and to evaluate the clinical efficacy of MT contrast (C) in diagnosis of liver diseases via binomial pulsed saturation, with and without the administration of the paramagnetic agent gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA). Fifty-one cases of liver disorders were included in this study. Among the more important findings were the following: a) cirrhotic livers have significantly higher MT indices than normal liver, while hepatoma, metastatic tumor and fatty liver have sub-normal MT indices; b) in general, although with notable exceptions, images with MT give significantly better contrast indices than control images; and c) MT with Gd-DTPA rarely fares any better than the MT technique alone, although again with notable exceptions. MTC is a potentially powerful technique for diagnosing liver diseases, provided it can be optimally exploited for each individual disease type.

Carcinoma, Hepatocellular↗
PubMed1989

Histopathologic characteristics and nuclear DNA content as prognostic factors in medullary thyroid carcinoma. A nationwide study in Sweden. The Swedish MTC Study Group.

Complete follow-up for 4 to 27 years was achieved for virtually all 249 patients with medullary thyroid carcinoma (MTC) diagnosed in Sweden in a 23-year period. Tumor specimens from 241 patients were re-examined with regard to calcitonin immunoreactivity, amyloid content, argyrophil reaction, tumor capsule condition, and nuclear DNA content. In univariate analyses, these factors, with the exception of the argyrophil reaction, were strong predictors of survival. There were twofold-to-threefold differences in hazard rate between patients with a high (greater than 50%) and low (less than 10%) frequency of calcitonin-immunoreactive tumor cells, between those with amyloid-containing and amyloid-free tumors, and between those with an intact and a nonintact tumor capsule. Calcitonin immunoreactivity and the amyloid content also provided prognostic information in multivariate analyses that adjusted for all the other factors mentioned above and in the full multivariate model, which in addition considered age, sex, heredity, stage of the disease, tumor size, and treatment. The strong prognostic capacity of the nuclear DNA content found in univariate analyses became considerably weaker when other morphologic characteristics were considered.

Adult↗
PubMed1979

Results of regular study on radionuclidic purity of 99mTc obtained from 99Mo--99mTc generators.

A total of 39 99mTc eluates obtained from 9 99Mo--99mTc generators delivered by The Radiochemical Centre Amersham during one year was studied with regard to their radionuclide purity. Using a Ge(Li) spectrometer the contaminants 60Co, 103Ru, 131I, 134Cs, 140Ba, 140La and 188Re were found in 99mTc-eluates with average levels ranging from 2.9 X 10(-3) to 2.8 X 10(-1) per cent of 99mTc activity. The additional total body absorbed dose caused by these contaminants, as calculated from their average content in 99mTc eluates, was less than 1% of the dose due to 99mTc pertechnetate.

Radiation Dosage↗
PubMed1997

Noninvasive stress testing of myocardial ischemia: comparison of GRE-MRI perfusion and wall motion analysis to 99 mTc-MIBI-SPECT, relation to coronary angiography.

In the evaluation of ischemic heart disease only MR imaging seems to have the potential to assess myocardial perfusion, function, and coronary morphology on a single instrument. The aim of this study was to assess the feasibility of a stress test with dipyridamole (0. 56 mg/kg) to analyze myocardial perfusion by Gd first-pass enhancement in ultrafast gradient-recalled-echo MRI (perf-MRI), and wall motion by cine gradient-recalled-echo MRI (Cine-MRI) in one imaging session. Twelve patients underwent complete rest and stress studies; satisfactory MR images were acquired in 10 patients. By 99 mTc-MIBI-SPECT sensitivities to detect ischemic segments were 66.7 % with Perf-MRI, 80.0 % with WM-MRI and 86.7 % for Perf-WM-MRI (Perf-MRI vs Perf-WM-MRI; p = 0.03). Scar was equally detected with a sensitivity of 91.6 % with either MRI technique. Thus, Perf-Cine-MRI provides complementary information for the management of ischemic heart disease and has a higher sensitivity than Perf-MRI alone.

Contrast Media↗
PubMed1991

Magnetization transfer contrast (MTC) in flash MR imaging.

Magnetization transfer between bound and free protons was used as a source of contrast in high speed MR imaging using the FLASH technique. Contrast in FLASH MR images was found to depend upon the reduced magnetization and the spin lattice relaxation rate of free protons in the presence of bound proton radio-frequency saturation. MTC FLASH imaging was thus used to estimate the variation with saturation frequency of free proton spin-lattice relaxation during magnetization transfer.

Animals↗
PubMed1991

Cyclotron production of NCA 99mTc and 99Mo. An alternative non-reactor supply source of instant 99mTc and 99Mo----99mTc generators.

The direct production of no-carrier-added (NCA) 6.02 h 99mTc and of 66 h 99mMo using proton beams of natural Mo targets was investigated. The major objective of this work was to evaluate the potential of utilizing high-intensity proton accelerators as a supply source of 99mTc and 99Mo for use in diagnostic nuclear medicine. The excitation functions for the production of the directly-made 99mTc via the 100Mo(p, 2n)99mTc (Q = -7.85 MeV) reaction, and of its parent 99Mo via the 100Mo(p, pn) 99Mo (Q = -8.30 MeV) and 100Mo(p, 2p)99mNb(15 s)----99Mo (Q = -11.14 MeV) reactions, were measured in the 68-8 MeV energy range. Single and cumulative yields for 99mTc and 99Mo, and for other Tc, Mo, Zr, Nb and Y radiocontaminants were also determined. The prospects of integrating the use of enriched 100Mo targets with high-intensity, dual beam, H- accelerators was analyzed. The potential of this combined method to replace or complement the current reactor-based supply sources of 99Mo----99mTc generators, is also discussed. Finally, a brief analysis is made on the potential use of this combined technology to support the anticipated expansion of nuclear medicine in developing nations.

Molybdenum↗
PubMed1999

Escherichia coli MTC, a NADPH cytochrome P450 reductase competent mutagenicity tester strain for the expression of human cytochrome P450: comparison of three types of expression systems.

Currently three different methods have been taken to develop new mutagenicity tester strains containing human cytochrome P450s (CYPs). Each of these use a single expression vector. In this paper we describe a fourth approach, i.e., the coexpression of a CYP and its electron-transfer flavoprotein, NADPH CYP reductase (RED), encoded by two different expression vectors. The Escherichia coli mutagenicity tester strain BMX100 has been expanded to a strain, MTC which stably expresses human RED. This new tester strain permits the biplasmid coexpression of human CYP1A2 and RED (MTC1A2). This novel strain can be used for the determination of the mutagenicity of chemicals known to be procarcinogens and metabolized by CYP1A2. The mutagenicity tester strain MTC1A2 was compared with: (i) BMX100 using the post-mitochondrial rat liver fraction (S9); (ii) BMX100 with expressing CYP1A2 alone (iii) or with expressing CYP1A2 fused to rat RED or (iv) with expressing CYP1A2, bicistronically coexpressed with rat RED. The biplasmid RED/CYP coexpression system generated a strain with the highest methoxy- and ethoxy-resorufin dealkylase activities and the highest mutagenic activities for the procarcinogens 2-aminoanthracene (2AA), aflatoxin B1 (AFB1) and 2-amino-3-methylimidazo(4,5-f)quinoline (IQ). Furthermore, the metabolism of 2AA and IQ was detected more efficiently using the MTC1A2 strain than with the BMX100 strain plus the standard rodent liver S9 metabolic system.

Animals↗
PubMed1999

Escherichia coli MTC, a human NADPH P450 reductase competent mutagenicity tester strain for the expression of human cytochrome P450 isoforms 1A1, 1A2, 2A6, 3A4, or 3A5: catalytic activities and mutagenicity studies.

We report here on the genetic engineering of four new Escherichia coli tester bacteria, coexpressing human CYP1A1, CYP2A6, CYP3A4 or CYP3A5 with human NADPH cytochrome P450 reductase (RED) by a biplasmid coexpression system, recently developed to express human CYP1A2 in the tester strain MTC. The four new strains were compared for CYP- and RED-expression levels and CYP activities with the formerly developed CYP1A2 expressing strain. CYP1A2 and CYP2A6 were expressed at the highest, CYP1A1 at the lowest and CYP3A4 and CYP3A5 at intermediate expression levels. Membranes of all five tester bacteria demonstrated similar RED-expression levels, except for the two CYP3A-containing bacteria which demonstrated slightly increased RED-levels. CYP-activities were determined as ethoxyresorufin deethylase (CYP1A1 and CYP1A2), coumarin 7-hydroxylase (CYP2A6) and erythromycin N-demethylase (CYP3A4 and CYP3A5) activities. Reaction rates were comparable with those obtained previously for these CYP-enzymes, except for CYP3A5 which demonstrated a lower activity. Benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene demonstrated mutagenicity in the CYP1A1 expressing strain with mutagenic activities, respectively, approximately 10-fold and 100-fold higher as compared with those obtained with the use of rat liver S9 fraction. Aflatoxin B1 demonstrated a significant mutagenicity with all CYP expressing strains, albeit lower as compared to those obtained with the use of rat liver S9. CYP1A2 was approximately 3-fold more effective in generating a mutagenic response of AFB1 as compared to CYP3A4. CYP3A5 and CYP3A4 demonstrated comparable capacities in AFB1 bioactivation which was equal as found for CYP1A1. It is concluded that these four new strains contain stable CYP- and RED-expression, significant CYP-activities and demonstrated significant bioactivation activities with several diagnostic carcinogens.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

Sodium dodecyl sulfate-sensitive septation in a mitomycin C-sensitive, mtc, mutant of Escherichia coli.

A mitomycin C-sensitive, mtc, mutant of Escherichia coli has an altered cell surface and is sensitive to sodium dodecyl sulfate (SDS). The mutant, M27, formed multinucleate nonseptated filaments in the presence of a low concentration of SDS (50 microgram/ml). When the culture grown at that concentration of SDS was diluted with an SDS-free medium, the filaments began to divide at a very rapid rate after a lag of about 20 min. Chloramphenicol inhibited this recovery division when added within 10 min after SDS dilution but did not inhibit the division when added 20 min after dilution. Penicillin G at a low concentration, which is enough to cause filamentation, had virtually no effect on the recovery division of SDS-induced filaments. The division of penicillin G-induced filaments was inhibited by SDS.

Chloramphenicol↗
PubMed1989

The development of a two-site enzyme immunometric assay (EIA) for calcitonin and its application in the measurement of the hormone in normal subjects, MTC-patients and post-menopausal women.

We have developed a sensitive, two-site enzyme immunometric assay (EIA) using high affinity monoclonal antibodies for the measurement of immunoreactive human calcitonin (i-hCT) and compared the performance of the assay with that of the conventional radioimmunoassay (RIA). The sensitivity of an overnight EIA (2 pmol/l) was comparable with the long incubation (7 days) RIA. Both, the EIA and the RIA have been applied for the measurement of i-hCT in three groups: normal volunteers (n = 53), post-menopausal women (n = 25) and patients with MTC (n = 20). The results showed that in all three groups, the level of i-hCT was somewhat lower than that measured by RIA due to its greater specificity. The EIA can provide an attractive alternative to the conventional RIA for both routine diagnostic work and physiological studies.

Antibodies, Monoclonal↗
PubMed1989

Magnetization transfer contrast (MTC) and tissue water proton relaxation in vivo.

In this study the exchange between 1H magnetization in "free" water (1Hf) and that in a pool with restricted motion (1Hr) was observed in tissues in vivo using NMR saturation transfer methods. Exchange between these two pools was demonstrated by a decrease in the steady-state magnetization and relaxation times of 1Hf with radiofrequency irradiation of 1Hr. The pseudo-first-order rate constant for the movement of magnetization from 1Hf to 1Hr was approximately 1 s-1 in kidney and approximately 3 s-1 in skeletal muscle in vivo. Proton NMR imaging demonstrated that this exchange was tissue specific and generated a novel form of NMR image contrast. The extent of exchange between 1Hf and 1Hr as well as the topological correlation of the exchange with relaxation weighted images suggests that this pathway is a major determinant of the observed relaxation properties of water 1H in vivo.

Animals↗
PubMed1978

The interpretation of phlebograms using fibrinogen labeled with 99 mTc.

A new method for the detection of deep-vein thrombosis is presented, consisting of a single antecubital injection of fibrinogen labeled with 99mTc. This atraumatic procedure allows one to visualize the large veins of the lower limbs, the venae iliacae and the distal part of the vena cava inferior. This paper discusses how to interpret these phlebograms.

Fibrinogen↗