Incidence patterns of orofacial clefts in purebred dogs.

Cleft lip (CL), cleft palate (CP) and cleft lip and palate (CLP) are the most common types of orofacial clefts in dogs. Orofacial clefts in dogs are clinically relevant because of the associated morbidity and high newborn mortality rate and are of interest as comparative models of disease. However, the incidence of CL, CP and CLP has not been investigated in purebred dogs, and the financial impact on breeders is unknown. The aims of this study were to document the incidence patterns of CL, CP and CLP in different breeds of dogs, determine whether defect phenotype is associated with skull type, genetic cluster and geographic location, and estimate the financial impact in breeding programs in the United States by means of an anonymous online survey. A total of 228 orofacial clefts were reported among 7,429 puppies whelped in the 12 preceding months. Breeds in the mastiff/terrier genetic cluster and brachycephalic breeds were predisposed to orofacial clefts. Certain breeds in the ancient genetic cluster were at increased odds of orofacial clefts. Male purebred dogs were at increased odds of CPs. Results confirm that brachycephalic breeds are overrepresented among cases of orofacial clefts. Furthermore, geographic region appeared to be a relevant risk factor and orofacial clefts represented a considerable financial loss to breeders. Improved understanding of the epidemiology of orofacial clefts (frequency, causes, predictors and risk factors) may help in identifying ways to minimize their occurrence. Information gained may potentially help veterinarians and researchers to diagnose, treat and prevent orofacial clefts.

Induction of apoptosis and cell cycle arrest by imexon in human pancreatic cancer cell lines.

Imexon is an aziridine-containing small molecule currently in Phase I clinical trials. This agent has been shown to bind to thiols and increase intracellular oxidants, inducing apoptosis in hematologic cancer cells. Pancreatic cancers are known to be sensitive to oxidation, suggesting this disease may be an appropriate target for this agent. The current report examines the activity of imexon in pancreatic cells. Imexon induced concentration-dependent and time-dependent apoptosis in a panel of six human pancreatic carcinoma cell (PCC) lines. The mean IC50 (SD) for growth inhibition by the SRB assay was 200 (101) microM for a 48 h exposure with a range of 64-358 microM. Cell killing was schedule-dependent, favoring exposure times > or =48 h. Imexon-treated MiaPaCa-2 cells underwent non-lethal growth arrest following exposure to concentrations < or =200 microM for 48 h. When concentrations were increased to 300 microM for > or =48 h, the MiaPaCa-2 cells arrested in G2 phase and activated caspases 3, 8, and 9 were detected. After a 72 h exposure to the IC80 concentration of imexon, cells exhibited a loss of mitochondrial membrane potential detected by CMXRos staining. However, there was no loss of reduced cellular thiols unless very high concentrations of > or =400 microM were used. In contrast, reactive oxygen species (ROS) were elevated in a dose-dependent fashion, starting at very low imexon concentrations. Imexon also significantly inhibited MiaPaCa-2 tumor growth in SCID mice at 100 mg/kg/d for 9 d. The tumor growth inhibition (% T/C) was 27% of control, and the tumor growth delay was 21 d, indicating an active agent by NCI standards. The levels of imexon that are cytotoxic in human PCC's are achievable based on the preliminary results of the ongoing Phase I trial. Imexon appears to be active against PCCs in vitro and has an entirely novel mechanism of action involving G2 arrest, accumulation of ROS, and the induction of apoptosis.

Evaluation of 4-dimensional computed tomography to 4-dimensional cone-beam computed tomography deformable image registration for lung cancer adaptive radiation therapy.

PURPOSE: To evaluate 2 deformable image registration (DIR) algorithms for the purpose of contour mapping to support image-guided adaptive radiation therapy with 4-dimensional cone-beam CT (4DCBCT). METHODS AND MATERIALS: One planning 4D fan-beam CT (4DFBCT) and 7 weekly 4DCBCT scans were acquired for 10 locally advanced non-small cell lung cancer patients. The gross tumor volume was delineated by a physician in all 4D images. End-of-inspiration phase planning 4DFBCT was registered to the corresponding phase in weekly 4DCBCT images for day-to-day registrations. For phase-to-phase registration, the end-of-inspiration phase from each 4D image was registered to the end-of-expiration phase. Two DIR algorithms-small deformation inverse consistent linear elastic (SICLE) and Insight Toolkit diffeomorphic demons (DEMONS)-were evaluated. Physician-delineated contours were compared with the warped contours by using the Dice similarity coefficient (DSC), average symmetric distance, and false-positive and false-negative indices. The DIR results are compared with rigid registration of tumor. RESULTS: For day-to-day registrations, the mean DSC was 0.75 ± 0.09 with SICLE, 0.70 ± 0.12 with DEMONS, 0.66 ± 0.12 with rigid-tumor registration, and 0.60 ± 0.14 with rigid-bone registration. Results were comparable to intraobserver variability calculated from phase-to-phase registrations as well as measured interobserver variation for 1 patient. SICLE and DEMONS, when compared with rigid-bone (4.1 mm) and rigid-tumor (3.6 mm) registration, respectively reduced the average symmetric distance to 2.6 and 3.3 mm. On average, SICLE and DEMONS increased the DSC to 0.80 and 0.79, respectively, compared with rigid-tumor (0.78) registrations for 4DCBCT phase-to-phase registrations. CONCLUSIONS: Deformable image registration achieved comparable accuracy to reported interobserver delineation variability and higher accuracy than rigid-tumor registration. Deformable image registration performance varied with the algorithm and the patient.

Interfractional positional variability of fiducial markers and primary tumors in locally advanced non-small-cell lung cancer during audiovisual biofeedback radiotherapy.

PURPOSE: To evaluate implanted markers as a surrogate for tumor-based setup during image-guided lung cancer radiotherapy with audiovisual biofeedback. METHODS AND MATERIALS: Seven patients with locally advanced non-small-cell lung cancer were implanted bronchoscopically with gold coils. Markers, tumor, and a reference bony structure (vertebra) were contoured for all 10 phases of the four-dimensional respiration-correlated fan-beam computed tomography and weekly four-dimensional cone-beam computed tomography. RESULTS: The systematic/random interfractional marker-to-tumor centroid displacements were 2/3, 2/2, and 3/3 mm in the x (lateral), y (anterior-posterior), and z (superior-inferior) directions, respectively. The systematic/random interfractional marker-to-bone displacements were 2/3, 2/3, and 2/3 mm in the x, y, and z directions, respectively. The systematic/random tumor-to-bone displacements were 2/3, 2/4, and 4/4 mm in the x, y, and z directions, respectively. All displacements changed significantly over time (p < 0.0001). CONCLUSIONS: Although marker-based image guidance may decrease the risk for geometric miss compared with bony anatomy-based positioning, the observed displacements between markers and tumor centroids indicate the need for repeated soft tissue imaging, particularly in situations with large tumor volume change and large initial marker-to-tumor centroid distance.

Imexon enhances gemcitabine cytotoxicity by inhibition of ribonucleotide reductase.

PURPOSE: Gemcitabine (GEM) is currently the standard first line treatment for pancreatic cancer; however, the overall survival of patients with this disease remains poor. Imexon is a pro-oxidant small molecule which produced a high response rate in combination with GEM in a phase I trial in pancreatic cancer. In this study, we investigate the combination of GEM with a novel redox-active agent, imexon, in vitro and in vivo. METHODS: Median effect analysis was used for in vitro combination cytotoxicity. The effect of imexon on GEM metabolism and uptake into cells and into DNA and effects on ribonucleotide reductase (RNR) were examined in vitro. The pharmacokinetics and antitumor efficacy of the imexon/GEM combination was evaluated in mouse models. RESULTS: In three human pancreatic cancer lines, there was additivity for the imexon/GEM combination. There was significantly greater efficacy for the drug combination in Panc-1 xenograft tumors. A pharmacokinetic study in mice showed a near doubling in the AUC of imexon when GEM was co-administered, with no effect of imexon on GEM's pharmacokinetic disposition. In vitro, imexon did not alter GEM's metabolism or uptake into DNA, but significantly inhibited RNR, and this effect was greater when combined with GEM. CONCLUSIONS: These results suggest that the interaction between imexon and GEM may be due to complimentary inhibition of RNR plus an enhanced exposure to imexon when the GEM is administered in vivo. This combination is currently being tested in a randomized phase II trial in pancreatic cancer.