BACKGROUND: Significant hepatobiliary accumulation of technetium 99m-labeled cardiac perfusion agents has been shown to cause alterations in the apparent localization of the agents in the cardiac walls. A Monte Carlo study was conducted to investigate the hypothesis that the cardiac count changes are due to the inconsistencies in the projection data input to reconstruction, and that correction of the causes of these inconsistencies before reconstruction, or including knowledge of the physics underlying them in the reconstruction algorithm, would virtually eliminate these artifacts. METHODS AND RESULTS: The SIMIND Monte Carlo package was used to simulate 64 x 64 pixel projection images at 128 angles of the three-dimensional mathematical cardiac-torso (MCAT) phantom. Simulations were made of (1) a point source in the liver, (2) cardiac activity only, and (3) hepatic activity only. The planar projections and reconstructed point spread functions (PSFs) of the point source in the liver were investigated to study the nature of the inconsistencies introduced into the projections by imaging, and how these affect the distribution of counts in the reconstructed slices. Bull's eye polar maps of the counts at the center of the left ventricular wall of filtered back-projection (FBP) and maximum-likelihood expectation-maximization (MLEM) reconstructions of projections with solely cardiac activity, and with cardiac activity plus hepatic activity scaled to have twice the cardiac concentration, were compared to determine the magnitude and location of apparent changes in cardiac activity when hepatic activity is present. Separate simulations were made to allow the investigation of stationary spatial resolution, distance-dependent spatial resolution, attenuation, and scatter. The point source projections showed significant inconsistencies as a function of projection angle with the largest effect being caused by attenuation. When consistent projections were simulated, no significant impact of hepatic activity on cardiac counts was noted with FBP, or 100 iterations of MLEM. With inconsistent projections, reconstruction of 180 degrees resulted in greater apparent cardiac count losses than did 360 degrees reconstruction for both FBP and MLEM. The incorporation of attenuation correction in MLEM reconstruction reduced the changes in cardiac counts to that seen in simulations in which attenuation was not included, but resulted in increased apparent localization of activity in the posterior wall of the left ventricle when scatter was present in the simulated images. CONCLUSIONS: The apparent alterations in cardiac counts when significant hepatic localization is present is due to the inconsistency of the projections inherent in imaging. Prior correction of these, or accounting for them in the reconstruction algorithm, will virtually eliminate them as causes of artifactual changes in localization. Attenuation correction and scatter correction are both required to overcome the major sources of apparent count changes in the heart associated with hepatic uptake.

Artifacts↗

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Successful treatment of diabetes in NOD mice with advanced disease by islet isografts following immunoregulation with Linomide (quinoline-3-carboxamide).

We have recently documented that oral Linomide (quinoline-3-carboxamide) prevents autoimmune insulitis, islet destruction, and diabetes in NOD mice treated at an early stage (5 wk of age) of the disease. In this report, we show that treatment of female NOD mice with advanced disease (age 23-24 wk) by syngeneic islet transplantation and oral Linomide administration results in prevention of graft insulitis and diabetes in the Linomide group up to 40 wk (diabetes at 40 wk: isograft recipients with Linomide n = 0 of 6; isograft recipients alone n = 5 of 6; p < 0.0001). The extent of protection from glucose intolerance by the combination of transplantation with Linomide was superior to that of Linomide alone [blood glucose (mean +/- SD) 60 min post-i.p. injection of 1 g/kg body weight glucose: Linomide plus isograft 6.7 +/- 1 mmol/L; Linomide alone 18.7 +/- 6.3 mmol/L; p < 0.0001]. Thus, Linomide should be considered a potential immunoregulatory modality in patients undergoing pancreatic islet or whole organ transplantation.

Adjuvants, Immunologic↗

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Early onset of diabetes mellitus associated with the mitochondrial DNA T14709C point mutation: patient report and literature review.

We report a family in which a mother and son were affected with diabetes mellitus and myopathy characterized by ragged red fibers and suggestive of mitochondrial disease. Mitochondrial DNA (mtDNA) analysis of DNA isolated from peripheral blood showed a T-->C point mutation at nucleotide position 14709, in the transfer RNA gene for glutamic acid. We review the association of diabetes and mtDNA mutations. This child's case is unusual because of the early onset of diabetes, which is more typical of mtDNA deletions.

Adult↗

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Issues in the development of gene therapy: preclinical experiments in E1A gene delivery.

We recently completed a phase I trial of E1A gene therapy for patients with advanced breast or ovarian cancers. The trial's rationale was that E1A gene would downregulate HER-2/neu expression by repressing the gene's transcription, thus reversing the malignant phenotype. Our preclinical studies showed that i) transfection capabilities were not reduced in preparing E1A/cationic liposome complexes, ii) samples after ex vivo transfection, and iii) HER-2/neu gene expression could be quantified by quantitative imaging analysis. These results facilitated the translation of our basic research findings into a clinical trial and to obtain final approval from the National Institutes of Health Recombinant DNA Advisory Committee.

Adenovirus E1A Proteins↗

PubMedDate not supplied

Mutant SV40 large T antigen as a therapeutic agent for HER-2/neu-overexpressing ovarian cancer.

The HER-2/neu gene is frequently amplified and/or its protein product, p185, is overexpressed in a number of human cancers. Overexpression of p185 correlates with poor prognosis and low survival rates in ovarian cancer patients. We previously found that the K1 mutant of SV40 large T antigen inhibits rat neu promoter and suppresses mutation-activated rat neu transformation in mouse fibroblasts. We show here that K1 also inhibits human HER-2/neu promoter in human ovarian cancer cells. To investigate whether K1 can suppress HER-2/neu transformation and thus is a potential therapeutic agent, we used an orthotopic ovarian cancer model in which mice were injected intraperitoneally with HER-2/neu-overexpressing human ovarian cancer cells to induce tumor development. The tumor-bearing mice were then treated with K1-liposome complex weekly. We found that liposome-mediated K1 gene transfer decreased the p185 protein level by K1 expression in these cancer cells and significantly prolonged mice survival; about 40% of these treated mice were alive for more than 1 year without any tumor development. On the other hand, the animals from control groups that did not receive this gene therapy all developed tumors and died within 7 months. The results indicate that liposome-mediated K1 gene transfer is able to suppress tumor development from HER-2/neu-overexpressing ovarian cancer cells in mice.

Animals↗