Lung tumor development and spontaneous regression in lambs coinfected with Jaagsiekte sheep retrovirus and ovine lentivirus.

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring and experimentally inducible lung cancer of sheep caused by Jaagsiekte sheep retrovirus (JSRV). The first aim of this study was to monitor the development of OPA with minimally invasive, real-time observations of animals experimentally infected with JSRV as well as ovine lentivirus (maedi-visna virus). Worldwide, simultaneous infection of sheep with these 2 retroviruses is a common occurrence, naturally and experimentally; consequently, the lung tumor homogenates used as inocula contained both viruses. Following inoculation, computed tomography was used to detect tumor nodules early, before the onset of clinical signs, and to monitor tumor advancement. However, not only was OPA disease progression observed, but the apparent spontaneous regression of OPA was witnessed. In fact, regression was more common than progression following JSRV inoculation of neonatal lambs. Immune responses were detected, particularly involving CD3(+) T cells and the production of antibodies against JSRV that may mediate the spontaneous regression of JSRV-induced OPA. The second aim of this study was to determine whether OPA tumors harbor genetic alterations similar to those found in human lung adenocarcinoma. No mutations were found in the tyrosine kinase domain of the epidermal growth factor receptor, KRAS codons 12 and 13, or the DNA-binding domain of p53 in tumor DNA from naturally occurring and experimentally-induced OPA cases. Overall, the genetic profile combined with the disease development data provides further important characterization of OPA and describes, for the first time, spontaneous regression of OPA tumors in experimentally infected sheep.

Biodistribution of boron in dogs with spontaneous intracranial tumors following borocaptate sodium administration.

Borocaptate sodium (Na2B12H11SH) is a potentially useful compound for boron neutron capture therapy of intracranial tumors. Tumor and normal tissue boron concentrations were evaluated in 30 dogs with naturally occurring intracranial tumors after i.v. borocaptate sodium infusion (55 mg boron/kg). Postmortem tissue boron concentrations were measured for three postinfusion time periods (2, 6, and 12 h) by inductively coupled plasma atomic emission spectroscopy. Mean boron concentrations for extracerebral tumors were 40.6 +/- 16.9 (2 h; n = 8), 25.9 +/- 11.7 (6 h; n = 5), and 8.6 +/- 4.5 micrograms boron/g (12 h; n = 6). Mean boron concentrations for intracerebral tumors were 30.6 +/- 17.5 (2 h; n = 7) and 2.9 +/- 1.8 micrograms boron/g (6 h; n = 4). Mean tumor boron concentrations were lower at longer postinfusion times. The tumor:normal brain boron concentration ranged from 0.8 to 19.8. Tumor:blood boron concentrations were less than one for all but three dogs and ranged from 0.04 to 1.4. Mean peritumor boron concentrations were highly variable but exceeded that of normal brain in 10 of 20 dogs. In some dogs, the mean peritumor boron concentration was similar to or exceeded the tumor boron concentration. Distant or contralateral normal brain had consistently low boron concentrations. Some cranial and systemic tissues had high boron concentrations, indicating substantial extravascular boron. The spontaneous animal tumors provided a realistic spectrum of data and enabled extensive sampling of diseased and normal tissues. The biodistribution of boron from borocaptate sodium administration was partially favorable because of high tumor boron concentrations. Empirical radiation dose tolerance studies should be used to determine the impact of the unfavorably high boron concentration of blood and some cranial tissues.

Evaluation of 18F-FDG PET/CT as a diagnostic imaging and staging tool for feline oral squamous cell carcinoma.

18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (18FDG-PET/CT) has been shown to be effective for staging human oral squamous cell carcinoma (SCC) but its application for cats with oral SCC is unknown. Twelve cats with biopsy-proven oral SCC were imaged with whole body 18FDG-PET/CT to determine its value as a diagnostic imaging and staging tool and fine needle aspirates were obtained of accessible regional lymph nodes. All tumors were FDG avid and conspicuous on 18FDG-PET/CT images, with an average of the maximum standardized uptake value 9.88 ± 5.33 SD (range 2.9-24.9). Soft tissue infiltrative tumors that were subtle and ill defined on CT were highly visible and more extensive on FDG-PET/CT. Tumors invading the osseous structures were more similar in extent on 18FDG-PET/CT and CT although they were more conspicuous on PET images. Three cytologically confirmed metastases were hypermetabolic on PET, while two of those metastases were equivocal on CT.

Computed tomographic angiography under sedation in the diagnosis of suspected canine pancreatitis: a pilot study.

BACKGROUND: Computed tomography (CT) is highly accurate for diagnosing pancreatitis in humans. The diagnosis of pancreatitis in dogs is based on clinical signs, laboratory findings, and ultrasonographic (US) changes. There are, however, inherent limitations in relying on laboratory and ultrasound findings for the clinical diagnosis of pancreatitis in dogs. HYPOTHESIS/OBJECTIVES: We hypothesized that CT angiography would be a rapid and reliable method to confirm pancreatitis in dogs compared to ultrasonography. The aim was to describe the CT characteristics and compare them to ultrasound findings and correlate the CT appearance to the severity of the patients' clinical course. ANIMALS: A prospective pilot case series; 10 dogs with pancreatitis were enrolled if the history, clinical signs, laboratory, and ultrasonographic findings were indicative of pancreatitis. METHODS: A 3-phase angiographic CT was performed under sedation. Afterward, each dog had US-guided aspirates of the pancreas collected and blood drawn for cPLi assay. Images were evaluated for portion of visible pancreas, pancreatic size and margin, pancreatic parenchyma, presence of peripancreatic changes and contrast enhancement pattern. The results were compared with outcome. RESULTS: An enlarged, homogeneously to heterogeneously attenuating and contrast-enhancing pancreas with ill-defined borders was identified in all dogs. CT identified more features characterizing pancreatic abnormalities compared to US. Thrombi were found in 3/10 dogs. Three dogs with heterogeneous contrast enhancement had an overall poorer outcome than those with homogenous enhancement. CONCLUSIONS AND CLINICAL IMPORTANCE: CT angiography under sedation was used in dogs to confirm clinically suspected pancreatitis and identified clinically relevant and potentially prognostic features of pancreatitis in dogs.

Large animal normal tissue tolerance with boron neutron capture.

PURPOSE: Normal tissue tolerance of boron neutron capture irradiation using borocaptate sodium (NA2B12H11SH) in an epithermal neutron beam was studied. METHODS AND MATERIALS: Large retriever-type dogs were used and the irradiations were performed by single dose, 5 x 10 dorsal portal. Fourteen dogs were irradiated with the epithermal neutron beam alone and 35 dogs were irradiated following intravenous administration of borocaptate sodium. RESULTS: Total body irradiation effect could be seen from the decreased leukocytes and platelets following irradiation. Most values returned to normal within 40 days postirradiation. Severe dermal necrosis occurred in animals given 15 Gy epithermal neutrons alone and in animals irradiated to a total peak physical dose greater than 64 Gy in animals following borocaptate sodium infusion. Lethal brain necrosis was seen in animals receiving between 27 and 39 Gy. Lethal brain necrosis occurred at 22-36 weeks postirradiation. A total peak physical dose of approximately 27 Gy and blood-boron concentrations of 25-50 ppm resulted in abnormal magnetic resonance imaging results in 6 months postexamination. Seven of eight of these animals remained normal and the lesions were not detected at the 12-month postirradiation examination. CONCLUSION: The bimodal therapy presents a complex challenge in attempting to achieve dose response assays. The resultant total radiation dose is a composite of low and high LET components. The short track length of the boron fission fragments and the geometric effect of the vessels causes much of the intravascular dose to miss the presumed critical target of the endothelial cells. The results indicate a large dose-sparing effect from the boron capture reactions within the blood.

Tricyclic pyrone analogs: a new class of microtubule-disrupting anticancer drugs effective against murine leukemia cells in vitro.

Novel 1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano [4,3-b][1]benzopyrans were synthesized in Hua's laboratory (code names H5, H10, H14 and H15) and tested for their ability to prevent L1210 leukemic cells from synthesizing macromolecules and growing in vitro. The aryl groups of these tricyclic pyrone (TP) analogs are either 3, 4-dimethoxyphenyl in H5 and H15 or 3-pyridyl in H10 and H14. Since 50 M H5 and H10 both inhibit DNA synthesis and tumor cell growth by 79-100%, concentrations 25 M were used in this study to assess the structure-activity relationships for this class of compounds. At 10-25 M, H5 and H14 are more potent inhibitors of DNA, RNA and protein synthesis than H10. In contrast, at 5-25 M, H10 is much more effective than H5 and H14 at inhibiting the growth of L1210 cells over a 4-day period. Interestingly, H15 inhibits DNA synthesis as much as H10 but fails to alter tumor cell growth. This discrepancy between the ability of TPs to inhibit macromolecule synthesis and leukemic cell growth suggests that other molecular targets may be involved in the antitumor action of these drugs. Their short-term inhibition of nucleic acid synthesis is reversible following drug removal but their long-term inhibition of tumor cell growth is not. Moreover, 25 M H5 and H10 are not cytotoxic at 2 days but equally decrease cell viability at 4 days, suggesting that the potent and irreversible inhibition of cell proliferation observed 1-4 days after H10 treatment is not solely caused by drug cytotoxicity. The effectiveness of H10 as inhibitor of L1210 cell growth is comparable to that of a spectrum of representative anticancer drugs. A critical finding is that 5 M H10 blocks the polymerization of purified tubulin by 90% and, therefore, may be a novel microtubule de-stabilizing drug. Indeed, H10 inhibits tubulin polymerization and L1210 cell growth as much as 5 M of vincristine (VCR). In contrast, 5 M H5 alters neither tubulin polymerization nor tumor cell growth. The ability of H10 to disrupt microtubule dynamics indirectly suggests that TPs may be novel cell cycle-specific anticancer drugs useful for arresting mammalian cells in mitosis.

Pregnancy prophylaxis: parenteral postcoital estrogen.

A two-dose regimen of intravenous conjugated estrogen as a postcoital interceptive was studied retrospectively. One hundred eighteen women who presented themselves at the Louisville General Hospital emergency room with a history of involuntary intercourse received 50 mg of intravenous conjugated estrogen at the conclusion of their initial medical evaluation and a second 50-mg injection approximately 24 hours later. Three pregnancies occurred among the 92 women who were seen again 30 days or more after treatment. These women reported other episodes of unprotected intercourse in the treatment cycle. Twenty-six of the women treated were lost to follow-up. Complaints of side effects were uncommon. In this series, intravenous conjugated estrogen appears to have been acceptable management for women who had been raped if no other unprotected intercourse had taken place in the treatment cycle.

Antitumor activity of novel tricyclic pyrone analogs in murine leukemia cells in vitro.

New tricyclic pyrone derivatives were synthesized and tested for their ability to prevent L1210 leukemic cells from synthesizing DNA and growing in vitro. At 50 microM, a pyripyropene analog has no effect, whereas four pentahydro-3-aryl-1-oxopyrano[4,3-b][1]benzopyrans all inhibit DNA synthesis by 79-91% and tumor cell growth by 93-100%. These inhibitory effects are concentration dependent with IC50 around 8.5 microM for DNA synthesis at 2 hours and 1.1 microM for tumor cell growth at 4 days. The aryl groups of these antitumor agents are either 3,4-dimethoxyphenyl or 3-pyridyl. Introduction of a methyl group at C5a and a formyloxy or hydroxy group at C6 does not alter the antitumor effects of the 3,4-dimethoxyphenyl benzopyrans but reduces those of the 3-pyridyl benzopyrans, which, at 50 microM, inhibit DNA synthesis by only 32-49% and fail to alter tumor cell growth. The 4-hydroxy-6-(3-pyridyl)-2-pyrone has no effect and the tricyclic pyrones lacking aryl groups have very little inhibitory effects on DNA synthesis, suggesting that a greater conjugation is required for the antitumor activity. These molecules have never been reported and might be valuable to develop a new class of anticancer drugs.

Retrospective review of 50 canine intracranial tumors evaluated by magnetic resonance imaging.

Magnetic resonance imaging (MRI) was performed on 50 dogs with intracranial neoplasia. The following tumor features were assessed: axial origin, location, shape, growth pattern, MRI signal intensity, evidence for edema, and paramagnetic contrast enhancement. Histologic diagnosis included 5 intracranially invading nasal tumors, 7 pituitary tumors, 22 meningiomas, 6 choroid plexus tumors, 7 astrocytomas, 1 ependymoma, and 2 oligodendrogliomas. Axial origin, site, shape, and growth pattern were important diagnostic characteristics for tumor type. Signal intensity and contrast enhancement pattern allowed further differentiation. Characteristic MRI features that facilitate diagnosis and prognosis were identified. Accurate diagnosis of tumor type based on these features was not always possible because of similarities in MRI appearance for some tumors. Tissue biopsy remains necessary for definitive diagnosis of intracranial tumors.

Quantitative electroencephalography in dogs anesthetized with 2.0% end-tidal concentration of isoflurane anesthesia.

Quantitative electroencephalography was assessed in dogs under controlled, 2% end-tidal isoflurane anesthetic conditions, and each variable at each electrode site was tested for normal distribution. With the quantitative electroencephalographic system used, 16 values for each of 21 electrode sites were evaluated. Absolute power ratios also were evaluated. The methods for quantitative electroencephalographic recording and analysis appear to be readily adaptable to the dog. Most of the data do not conform to a normal distribution. Therefore, distribution-free nonparametric statistics should be used when looking for differences under experimental or clinical conditions. Quantitative electroencephalography appears to be a sensitive noninvasive method that could be used to evaluate brain function under anesthetic, clinical, and experimental settings.

Magnetic resonance imaging of the brain of a dog with hereditary polioencephalomyelopathy.

Hereditary polioencephalomyelopathy was suspected in a young, female Australian Cattle Dog on the basis of clinical signs, including seizures, progressive ataxia, and weakness. Magnetic resonance imaging (MRI) of the brain revealed multiple ovoid, bilaterally symmetric signal abnormalities that were hypointense or isointense on T1-weighted images and hyperintense on T2-weighted images. On necropsy, these areas of signal abnormalities corresponded to areas of malacia in various brain and brain stem nuclei. In addition, poliomalacia was detected at the cervical intumescence of the spinal cord. Histologic examination revealed rarefaction of neuropil and vacuolation of glial cells in these areas, which are lesions consistent with hereditary polioencephalomyelopathy of Australian Cattle Dogs.

Intracranial neoplasia.

A diagnosis of intracranial neoplasia in companion animals may be made by computed tomography (CT) or magnetic resonance imaging (MRI). MRI is the better method for detecting and characterizing intracranial tumors because of its superior depiction of soft tissues and relative lack of degrading artifacts, intracranial tumors may be characterized by distinct features; a systematic evaluation of these features on CT or MRI images may help to identify specific tumor types. In this article, guidelines for formulating differential diagnoses based on these imaging criteria will be discussed. Technical recommendations and protocols for CT and MR imaging will also be provided.

Determination of lesion volume by MRI and stereology in a macaque model of tuberculosis.

Sensitive and reproducible methods are needed to measure the impact on the host following experimental challenge with Mycobacterium tuberculosis, in order to determine the degree of protection conferred by new vaccines. Here we compare how well different clinical and post-mortem measures of disease burden predict the response by the host to increasing doses of M. tuberculosis in rhesus and cynomolgus macaques. The total lung and lesion volume was quantified from magnetic resonance imaging (MRI) digital stacks obtained from lungs of M. tuberculosis infected animals that were formalin fixed and scanned ex-vivo. The total lung lesion volume relative to the fixed whole lung volume was superior at indicating disease burden when compared to thoracic radiography, pathology scores, changes in body weight and temperature, as well as erythrocyte haemoglobin concentrations and sedimentation rate. The total lesion volume accurately reflected differences in challenge doses of M. tuberculosis that ranged from 30 to 500 CFU delivered by aerosol. The determination of total lesion volume from MR images demonstrated a species-dependent difference between rhesus and cynomolgus macaques in susceptibility to M. tuberculosis infection. MR stereology provides an accurate, quantifiable and relatively simple assessment, which can be easily standardized between laboratories and should form an essential component of the clinical assessment of disease progression, or vaccine efficacy.

Physical principles and technical considerations for equine computed tomography and magnetic resonance imaging.

This article discusses how cross-sectional imaging methods such as computed tomography and magnetic resonance imaging can provide unique and diagnostically important information in situations where radiography or diagnostic ultrasound have been unrewarding.

Type I congenital cystic adenomatoid malformation of the lungs in a Hereford calf.

A 3-day-old Hereford calf was presented for general weakness and severe dyspnoea. Lateral radiographs projections showed several compartmentalized gas filled structures in the caudodorsal thorax. At necropsy each diaphragmatic lung lobe contained a large cyst. Gross and histopathologic findings were consistent with a congenital type I cystic adenomatoid malformation of the lungs.

Plasma pharmacokinetics of warfarin enantiomers in cats.

The purpose of this study was to determine the dispositions of S-warfarin and R-warfarin in normal cats following intravenous and oral administrations of racemic warfarin. Citrated blood samples were collected from 10 cats prior to and at times 5, 15, and 30 min, 1, 2, 3, 4, 5, 6, 12, 24, 36, 48, 72, 96, and 120 h following a single intravenous bolus of 0.5 mg/kg of racemic warfarin. After a 21-day washout period, samples were then similarly collected in three groups of four cats for 120 h following oral administration of 0.1, 0.25, and 0.5 mg/kg racemic warfarin. S-warfarin and R-warfarin were detected using a high-performance liquid chromatography assay validated for cat plasma. Drug concentration-time curves were subjected to non-compartmental analysis. Median pharmacokinetic parameters associated with the intravenous administration of 0.5 mg/kg racemic warfarin were as follows: t1/2 (S:28.2, R:18.3 h), area under the plasma concentration-time curve (AUC; S:33.0, R:24.6 h*microg/mL), area under the moment curve (AUMC; S:1889, R:527.8 h*h*microg/mL), and mean residence time (MRT; S:38.7, R:20.9 h). For each parameter, S-warfarin was significantly different from R-warfarin (P<0.05). Warfarin was absorbed rapidly after oral administration, and the dosage did not affect the time to maximum concentration (S:0.87, R:0.75 h). Oral dosage significantly influenced maximum plasma concentration (ng/mL, S:1267, R:1355 at 0.5 mg/kg; S:614.9, R:679.4 at 0.25 mg/kg; S:250.5, R:367.6 at 0.1 mg/kg), AUC (h*microg/mL, S:45.12, R:30.91 at 0.5 mg/kg; S:22.98:, R:18.99 at 0.25 mg/kg; S:3.922, R:3.570 at 0.1 mg/kg) and AUMC (h*h*microg/mL, S:2135, R:1062 at 0.5 mg/kg; S:943.1, R:599.9 at 0.25 mg/kg; S:132.2, R:59.03 at 0.1 mg/kg), but not t1/2 (S:23.5, R:11.6 h) nor MRT (S:26.3, R:13.5 h). Both warfarin enantiomers were highly (>96.5%) protein-bound. Quantitation of the warfarin content in commercially available tablets indicated an unequal distribution of the drug throughout the tablet.

Pharmacodynamics of warfarin in cats.

The overall purpose of this study was to evaluate the pharmacodynamic response to warfarin in cats. The specific aim was to determine if a log-linear indirect response model (Nagashima et al., 1969) used to describe the in vivo effect of warfarin in humans could be applied to cats. The pharmacokinetics of racemic warfarin were described using a non-compartmental approach. The relationship between prothrombin complex activity (PCA) and normalized prothrombin time (PTR) was defined for feline plasma under our experimental conditions, and determined to be: %PCA=12.38+648 e-PTR/0.492. These data were then integrated and used to predict the warfarin dose associated with therapeutic anti-coagulation defined as an International Normalized Ratio (INR) of 2.0-3.0. The maximum prothrombinopenic response to warfarin in cats after a single intravenous dose of 0.5 mg/kg occurred at 24-48 h. Pharmacodynamic modeling suggested that each cat had a narrow therapeutic range of the steady-state concentration of total warfarin required to appropriately block prothrombin complex synthesis (median: 265.2-358.7 ng/mL). The median daily dose range predicted to yield therapeutic concentrations of warfarin was 0.061-0.088 mg/kg per day. Wide inter-individual variations in both pharmacokinetics and pharmacodynamic response suggest that a more optimal dosing of warfarin may be possible with the development of individual pharmacokinetic/pharmacodynamic algorithms, analogous to those currently employed in human patients.

Mensuration of the normal pituitary gland from magnetic resonance images in 96 dogs.

The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy.

A review: CNS effects and normal tissue tolerance in dogs.

Large animal studies have been utilized to define tolerance of normal brain to irradiation and verify treatment planning programs with two recently installed epithermal neutron beams. The normal brain tolerance studies utilized two biological endpoints, magnetic resonance visible damage only and neurologic signs progressing to death. The studies focused on defining the proton RBE for the contaminant fast neutrons, and from nitrogen capture of thermal neutrons and boron capture reaction biologic effect. The proton RBE was approximately 3.0 to 6.7, depending on whether a dose reduction factor for the low gamma dose rate was employed. The microscopic distribution of the boron compounds, coupled with the extremely short length of the fission fragments from thermal neutron capture by 10B yields an observed biologic effect much less than would be expected from such high LET irradiation. This observed biologic effect, which is a product of the microdistribution of the boron atom and the relative biologic effect of the fission fragments has been termed compound factor. The compound factor was based on the calculated physical dose from the fission fragment in blood based on measured blood 10B concentration. The approximate compound factor for BSH was studied at the two institutions and it ranged from 0.27 to 0.55, depending on the site and the endpoint chosen. The mean compound factor for BPA was only studied at one site and was found to be 1.1 for both endpoints. The increase in the compound factor for BPA is in keeping with previous calculations based on the differences in compound distribution. Results of these studies has helped the initiation of phase I and phase II clinical trials at Brook haven National Laboratory and the planned European clinical trials at Petten, The Netherlands.