Magnetic resonance electrical impedance tomography (MREIT) aims at producing high-resolution cross-sectional conductivity images of an electrically conducting object such as the human body. Following numerous phantom imaging experiments, the most recent study demonstrated successful conductivity image reconstructions of postmortem canine brains using a 3 T MREIT system with 40 mA imaging currents. Here, we report the results of in vivo animal imaging experiments using 5 mA imaging currents. To investigate any change of electrical conductivity due to brain ischemia, canine brains having a regional ischemic model were scanned along with separate scans of canine brains having no disease model. Reconstructed multi-slice conductivity images of in vivo canine brains with a pixel size of 1.4 mm showed a clear contrast between white and gray matter and also between normal and ischemic regions. We found that the conductivity value of an ischemic region decreased by about 10-14%. In a postmortem brain, conductivity values of white and gray matter decreased by about 4-8% compared to those in a live brain. Accumulating more experience of in vivo animal imaging experiments, we plan to move to human experiments. One of the important goals of our future work is the reduction of the imaging current to a level that a human subject can tolerate. The ability to acquire high-resolution conductivity images will find numerous clinical applications not supported by other medical imaging modalities. Potential applications in biology, chemistry and material science are also expected.

Extended-spectrum cephalosporin (ESC)-resistant Enterobacteriaceae is an increasingly important problem in both human and veterinary medicine. The aims of this study were to describe a comparative molecular characterization of Enterobacteriaceae carrying ESC resistance genes, encoding extended-spectrum β-lactamase (ESBL) and AmpC, isolated from human stool samples, rectal swabs from companion animals, and swabs from the environment of veterinarian hospitals in South Korea, and to examine their possible dissemination and transmission. The ESC resistance genes were identified by PCR and sequencing. Isolates with the predominant ESC resistance genes were assessed for their genetic relatedness by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. A total of 195 Escherichia coli and 41 Klebsiella pneumoniae isolates that exhibited ESC resistance were recovered on CHROMagar ESBL from human, companion animal, and the veterinary hospital environmental samples. In companion animals, most of the ESC resistance genes were bla CMY–2–like (26.4%), followed by bla CTX –M–55 (17.2%) and bla CTX–M–14 (16.1%), whereas bla CTX–M–15 (28.6%) was predominant in human samples. The epidemiological relatedness of isolates carrying ESC resistance genes, including 124 E. coli and 23 K. pneumoniae isolates carrying CMY-2-like, DHA-1-like, or/and CTX-M-type, were analyzed by PFGE. The pulsotypes of five E. coli isolates (three from dogs and two from humans) carrying bla CMY–2–like , which were attributed to sequence type 405, from different veterinary clinics showed >85% similarity. Our results indicate direct transmission and dissemination of ESC-resistant Enterobacteriaceae between humans and companion animals.

Studies of naturally occurring cancers in dogs, which share many genetic and environmental factors with humans, provide valuable information as a comparative model for studying the mechanisms of human cancer pathogenesis. While individual and small-scale studies of canine cancers are underway, more generalized multi-omics studies have not been attempted due to the lack of large-scale and well-controlled genomic data. Here, we produced reliable whole-exome and whole-transcriptome sequencing data of 197 canine mammary cancers and their matched controls, annotated with rich clinical and biological features. Our dataset provides useful reference points for comparative analysis with human cancers and for developing novel diagnostic and therapeutic technologies for cancers in pet dogs.

The use of 131I doses of several mCi for scans can stun the thyrocytes and thyroid cancer cells, whereas the usual dose (300 microCi) of 123I does not. We compared the diagnostic accuracy of the 123I (300 microCi) scans and that of 131I (3-10 mCi) scans in 155 patients. The diagnostic accuracy of a 123I scan in detecting functioning thyroid remnant/metastasis was 89.5% (77/86 scans) and that of a 131I scan was 92.9% (39/42) in 6 week-postoperative patients (p = 0.750). For radioablation therapy follow-up patients, the diagnostic accuracy of 123I in determining presence or absence of functioning remnant or metastasis was 69.4% (25/36) and that of 131I was 92.5% (49/53) with a p value of 0.079. The success rates for complete ablation of functioning tissue after radioiodine therapy administered after diagnostic 123I and after 131I were 72% (34/47) and 56% (24/43), respectively, with a p value of 0.125. Our study indicates the following: 1) for the first postoperative evaluation, the diagnostic accuracy of the 123I scan was essentially equal to that of the 131I scan, and the success rate of radioablation therapy appears to be better than 123I scan; and 2) for postablation follow-up surveys, the 131I scan appears to be better but carries the risk of stunning the functioning cells.

Most melanoma-positive SNs contain minute tumor volumes. Tumor thickness and patterns of SN metastases may not be predictive of tumor burden or the presence of positive NSNs.

We performed in vivo disease model animal experiments to validate the MREIT technique providing conductivity information of tissues in situ to be utilized in clinical applications.

Magnetic resonance electrical impedance tomography (MREIT) has the potential to provide conductivity images with high spatial resolution and accuracy. Recent studies using various conductivity phantoms showed that the spatial resolution could be similar to that of conventional MR images as long as enough current is injected. Before we try in vivo animal imaging studies using a small injection current of less than 5 mA, we have performed MREIT conductivity imaging of postmortem canine brains using 40 mA injection currents. The primary goals were to produce high-resolution conductivity images of white and gray matter in situ and to accumulate experimental techniques to undertake in vivo animal imaging studies in the near future. Reconstructed conductivity images of two canine brains with a pixel size of 1.4 x 1.4 mm(2) showed a clear conductivity contrast between gray and white matter. Considering the anisotropic conductivity of white matter, we interpreted reconstructed conductivity images as equivalent isotropic conductivity images. Estimated conductivity ratios of white to gray matter were between 1.13 and 1.20 depending on the choice of a region of interest in reconstructed images. A higher conductivity value of white matter compared with that of gray matter stems from the fact that the reconstructed equivalent isotropic conductivity value of white matter reflects a high conductivity of white matter in the direction parallel to its fibers. We expect that this kind of postmortem animal imaging can provide conductivity information on tissues in situ to be utilized in numerous modeling studies.

Sentinel lymph node biopsy is increasingly used to identify occult metastases in regional lymph nodes of patients with melanoma. Selection of patients for sentinel lymph node biopsy and subsequent lymphadenectomy is an area of debate. The purpose of this study was to describe a large clinical series of these biopsies for cutaneous melanoma and to identify patients most likely to gain useful clinical information from sentinel lymph node biopsy. The Indiana University Melanoma Program computerized database was queried to identify all patients who underwent this procedure for clinically localized cutaneous melanoma. It was performed using preoperative technetium Tc 99m lymphoscintigraphy and isosulfan blue dye. Pertinent demographic, surgical, and histopathologic data were recorded. Univariate and multivariate logistic regression and classification table analyses were performed to identify clinical variables associated with sentinel node and nonsentinel node positivity. In total, 234 biopsy procedures were performed to stage 291 nonpalpable regional lymph node basins. Mean Breslow's thickness was 2.30 mm (2.08 mm for negative sentinel lymph node biopsy, 3.18 mm for positive). The mean number of sentinel nodes removed was 2.17 nodes per basin (range, 1 to 8). Forty-seven of 234 melanomas (20.1 percent) and 50 of 291 basins (17.2 percent) had a positive biopsy. Positivity correlated with AJCC tumor stage: T1, 3.6 percent; T2, 8.1 percent; T3, 27.4 percent; T4, 44 percent. By univariate logistic regression, Breslow's thickness (p = 0.003, continuous variable), ulceration (p = 0.003), mitotic index > or = 6 mitoses per high power field (p = 0.008), and Clark's level (p = 0.04) were significantly associated with sentinel lymph node biopsy result. By multivariate analysis, only Breslow's thickness (p = 0.02), tumor ulceration (p = 0.02), and mitotic index (p = 0.02) were significant predictors of biopsy positivity. Classification table analysis showed the Breslow cutpoint of 1.2 mm to be the most efficient cutpoint for sentinel lymph node biopsy result (p = 0.0004). Completion lymphadenectomy was performed in 46 sentinel node-positive patients; 12 (26.1 percent) had at least one additional positive nonsentinel node. Nonsentinel node positivity was marginally associated with the presence of multiple positive sentinel nodes (p = 0.07). At mean follow-up of 13.8 months, four of 241 sentinel node-negative basins demonstrated same-basin recurrence (1.7 percent). Sentinel lymph node biopsy is highly reliable in experienced hands but is a low-yield procedure in most thin melanomas. Patients with melanomas thicker than 1.2 mm or with ulcerated or high mitotic index lesions are most likely to have occult lymph node metastases by sentinel lymph node biopsy. Completion therapeutic lymphadenectomy is recommended after positive biopsy because it is difficult to predict the presence of positive nonsentinel nodes.