Pulse-Administered Toceranib Phosphate Plus Lomustine for Treatment of Unresectable Mast Cell Tumors in Dogs.

BackgroundNonresectable mast cell tumors (MCT) in dogs remain a therapeutic challenge, and investigation of novel combination therapies is warranted. Intermittent administration of tyrosine kinase inhibitors (TKI) combined with cytotoxic chemotherapy may effectively chemosensitize canine MCT while decreasing cost and adverse effects associated with either agent administered as monotherapy.Hypothesis/objectivesThe primary study objectives were to (1) identify the maximally tolerated dose (MTD), (2) determine the objective response rate (ORR) and (3) describe the adverse event profile of pulse-administered toceranib phosphate (TOC) combined with lomustine.AnimalsForty-seven client-owned dogs with measurable MCT.MethodsToceranib phosphate was given PO on days 1, 3 and 5 of a 21-day cycle at a target dosage of 2.75 mg/kg. Lomustine was given PO on day 3 of each cycle at a starting dosage of 50 mg/m(2) . All dogs were concurrently treated with diphenhydramine, omeprazole, and prednisone.ResultsThe MTD of lomustine was established at 50 mg/m(2) when combined with pulse-administered TOC; the dose-limiting toxicity was neutropenia. Forty-one dogs treated at the MTD were evaluable for outcome assessment. The ORR was 46% (4 complete response, 15 partial response) and the overall median progression-free survival (PFS) was 53 days (1 to >752 days). On multivariate analysis, variables significantly associated with improved PFS included response to treatment, absence of metastasis, and no previous chemotherapy.Conclusions and clinical importanceCombined treatment with pulse-administered TOC and lomustine generally is well tolerated and may be a reasonable treatment option for dogs with unresectable or metastatic MCT

Can we continue research in splenectomized dogs? Mycoplasma haemocanis: Old problem - New insight

We report the appearance of a Mycoplasma haemocanis infection in laboratory dogs, which has been reported previously, yet, never before in Europe. Outbreak of the disease was triggered by a splenectomy intended to prepare the dogs for a hemorrhagic shock study. The clinical course of the dogs was dramatic including anorexia and hemolytic anemia. Treatment included allogeneic transfusion, prednisone, and oxytetracycline. Systematic follow-up (n=12, blood smears, antibody testing and specific polymerase chain reaction) gives clear evidence that persistent eradication of M. haemocanis is unlikely. We, therefore, had to abandon the intended shock study. In the absence of effective surveillance and screening for M. haemocanis, the question arises whether it is prudent to continue shock research in splenectomized dogs. Copyright (C) 2004 S. Karger AG, Basel

The biomechanics of amnion rupture: an X-ray diffraction study

Pre-term birth is the leading cause of perinatal and neonatal mortality, 40% of which are attributed to the pre-term premature rupture of amnion. Rupture of amnion is thought to be associated with a corresponding decrease in the extracellular collagen content and/or increase in collagenase activity. However, there is very little information concerning the detailed organisation of fibrillar collagen in amnion and how this might influence rupture. Here we identify a loss of lattice like arrangement in collagen organisation from areas near to the rupture site, and present a 9% increase in fibril spacing and a 50% decrease in fibrillar organisation using quantitative measurements gained by transmission electron microscopy and the novel application of synchrotron X-ray diffraction. These data provide an accurate insight into the biomechanical process of amnion rupture and highlight X-ray diffraction as a new and powerful tool in our understanding of this process

Regeneration of Cryoinjury Induced Necrotic Heart Lesions in Zebrafish Is Associated with Epicardial Activation and Cardiomyocyte Proliferation

In mammals, myocardial cell death due to infarction results in scar formation and little regenerative response. In contrast, zebrafish have a high capacity to regenerate the heart after surgical resection of myocardial tissue. However, whether zebrafish can also regenerate lesions caused by cell death has not been tested. Here, we present a simple method for induction of necrotic lesions in the adult zebrafish heart based on cryoinjury. Despite widespread tissue death and loss of cardiomyocytes caused by these lesions, zebrafish display a robust regenerative response, which results in substantial clearing of the necrotic tissue and little scar formation. The cellular mechanisms underlying regeneration appear to be similar to those activated in response to ventricular resection. In particular, the epicardium activates a developmental gene program, proliferates and covers the lesion. Concomitantly, mature uninjured cardiomyocytes become proliferative and invade the lesion. Our injury model will be a useful tool to study the molecular mechanisms of natural heart regeneration in response to necrotic cell death

Organotypical tissue cultures from adult murine colon as an in vitro model of intestinal mucosa

Together with animal experiments, organotypical cell cultures are important models for analyzing cellular interactions of the mucosal epithelium and pathogenic mechanisms in the gastrointestinal tract. Here, we introduce a three-dimensional culture model from the adult mouse colon for cell biological investigations in an in vivo-like environment. These explant cultures were cultured for up to 2 weeks and maintained typical characteristics of the intestinal mucosa, including a high-prismatic epithelium with specific epithelial cell-to-cell connections, a basal lamina and various connective tissue cell types, as analyzed with immunohistological and electron microscopic methods. The function of the epithelium was tested by treating the cultures with dexamethasone, which resulted in a strong upregulation of the serum- and glucocorticoid-inducible kinase 1 similar to that found in vivo. The culture system was investigated in infection experiments with the fungal pathogen Candida albicans. Wildtype but not Δcph1/Δefg1-knockout Candida adhered to, penetrated and infiltrated the epithelial barrier. The results demonstrate the potential usefulness of this intestinal in vitro model for studying epithelial cell-cell interactions, cellular signaling and microbiological infections in a three-dimensional cell arrangement

Characterization of the model for experimental testicular teratoma in 129/SvJ-mice

An animal model of experimental testicular teratoma has been established to study how a teratoma affects the host testis and how the host testis reacts against the teratoma. 129/SvJ-mice were used as experimental animals. To induce the experimental testicular teratoma, male gonadal ridges from 12-day-old 129/SvJ-mouse fetuses were grafted into the testes of adult mice for 1-12 weeks. The developing tumour was analysed by light and electron microscopy and by immunocytochemical localization of transcription factors SOX9 and c-kit, glial fibrillary acidic protein (GFAP) and type IV collagen. Testicular teratoma was observed in 36 out of 124 testes with implanted fetal gonadal ridges (frequency 29%). One spontaneous testicular teratoma was observed in this material from 70 male mice (1.5%). One week after implantation intracordal clusters of cells were seen in embryonic testicular cords of the graft as the first sign of testicular teratomas. Four weeks after implantation the embryonic testicular cords had totally disappeared from grafts with teratomas, and the tumour tissue had enlarged the testis and invaded the interstitium of the host testis. It consisted of solitary pieces of immature cartilage as well as of glial cells and of primitive neuroepithelium. Six to eight weeks after implantation the tumour tissue had expanded so that the enlarged testis could be detected by macroscopic enlargement of the scrotum. The testicular tissue of the host had practically disappeared, and only solitary disrupted seminiferous tubules of the host were seen surrounding the teratoma. Neuroepithelial structures of some teratomas cultured for 8 weeks had cells with a granular nucleus as a sign of obvious apoptosis. Eleven to 12 weeks after implantation the growth of the teratoma had stopped, and the histology corresponded to that of a mature cystic teratoma. GFAP, SOX9 and type IV collagen were strongly positive in some parts of the tumours cultured for 4 and 8 weeks, while only occasional c-kit-positive areas were observed in tumours cultured for 8 weeks. As conclusions: (1) the metastasizing capacity of the experimental testicular teratoma is very low during 12 weeks, but the behaviour of the tumour in the testicular tissue of the graft is invasive; (2) the growth of experimental testicular teratomas cease 6-8 weeks after implantation of the fetal gonadal ridges with the obvious apoptosis of the immature tissue components; (3) the model of experimental testicular teratoma in the mouse is suitable for studying how the teratoma affects the host testis and how the host testis reacts to teratoma

Herpes Simplex Virus Dances with Amyloid Precursor Protein while Exiting the Cell

Herpes simplex type 1 (HSV1) replicates in epithelial cells and secondarily enters local sensory neuronal processes, traveling retrograde to the neuronal nucleus to enter latency. Upon reawakening newly synthesized viral particles travel anterograde back to the epithelial cells of the lip, causing the recurrent cold sore. HSV1 co-purifies with amyloid precursor protein (APP), a cellular transmembrane glycoprotein and receptor for anterograde transport machinery that when proteolyzed produces A-beta, the major component of senile plaques. Here we focus on transport inside epithelial cells of newly synthesized virus during its transit to the cell surface. We hypothesize that HSV1 recruits cellular APP during transport. We explore this with quantitative immuno-fluorescence, immuno-gold electron-microscopy and live cell confocal imaging. After synchronous infection most nascent VP26-GFP-labeled viral particles in the cytoplasm co-localize with APP (72.8+/−6.7%) and travel together with APP inside living cells (81.1+/−28.9%). This interaction has functional consequences: HSV1 infection decreases the average velocity of APP particles (from 1.1+/−0.2 to 0.3+/−0.1 µm/s) and results in APP mal-distribution in infected cells, while interplay with APP-particles increases the frequency (from 10% to 81% motile) and velocity (from 0.3+/−0.1 to 0.4+/−0.1 µm/s) of VP26-GFP transport. In cells infected with HSV1 lacking the viral Fc receptor, gE, an envelope glycoprotein also involved in viral axonal transport, APP-capsid interactions are preserved while the distribution and dynamics of dual-label particles differ from wild-type by both immuno-fluorescence and live imaging. Knock-down of APP with siRNA eliminates APP staining, confirming specificity. Our results indicate that most intracellular HSV1 particles undergo frequent dynamic interplay with APP in a manner that facilitates viral transport and interferes with normal APP transport and distribution. Such dynamic interactions between APP and HSV1 suggest a mechanistic basis for the observed clinical relationship between HSV1 seropositivity and risk of Alzheimer's disease

A Tale of Four “Carp”: Invasion Potential and Ecological Niche Modeling

. We assessed the geographic potential of four Eurasian cyprinid fishes (common carp, tench, grass carp, black carp) as invaders in North America via ecological niche modeling (ENM). These “carp” represent four stages of invasion of the continent (a long-established invader with a wide distribution, a long-established invader with a limited distribution, a spreading invader whose distribution is expanding, and a newly introduced potential invader that is not yet established), and as such illustrate the progressive reduction of distributional disequilibrium over the history of species' invasions.We used ENM to estimate the potential distributional area for each species in North America using models based on native range distribution data. Environmental data layers for native and introduced ranges were imported from state, national, and international climate and environmental databases. Models were evaluated using independent validation data on native and invaded areas. We calculated omission error for the independent validation data for each species: all native range tests were highly successful (all omission values <7%); invaded-range predictions were predictive for common and grass carp (omission values 8.8 and 19.8%, respectively). Model omission was high for introduced tench populations (54.7%), but the model correctly identified some areas where the species has been successful; distributional predictions for black carp show that large portions of eastern North America are at risk.ENMs predicted potential ranges of carp species accurately even in regions where the species have not been present until recently. ENM can forecast species' potential geographic ranges with reasonable precision and within the short screening time required by proposed U.S. invasive species legislation