Resolution of persistent oral papillomatosis in a dog after treatment with a recombinant canine oral papillomavirus vaccine.

This report describes a 16-month-old female, otherwise seemingly healthy, Siberian husky dog with severe oral papillomatosis that did not regress spontaneously and was refractory to surgical treatment over a 6-month period. Regression of the papillomas was achieved by administering a series of experimental vaccinations starting at the time of the last surgery. The vaccine consisted of systemically administered canine oral papillomavirus major coat protein L1 that has been shown to self-assemble into virus-like particles. They cause a humoral response that has been shown to prevent the onset and development of papillomas. In this case, however, following unsuccessful surgical treatment, the vaccine acted therapeutically, causing the papillomas that had regrown to shrink. No side-effects were noted.

Preclinical safety evaluation of G207, a replication-competent herpes simplex virus type 1, inoculated intraprostatically in mice and nonhuman primates.

G207, a replication-competent herpes simplex virus type 1 (HSV-1) virus, has been previously shown to be effective against human prostate cancer xenografts in mice. This study assesses its safety in the prostate of two animal models known for their sensitivity to HSV-1. BALB/c mice were injected intraprostatically with either HSV-1 G207 or strain F and observed for 5 months. None of the G207-injected animals exhibited any clinical signs of disease or died. However, 50% of strain F-injected mice displayed sluggish, hunched behavior and died by day 13. Histopathologically, the G207-injected prostates were normal whereas strain F-injected prostates showed epithelial flattening, sloughing, and stromal edema. Four Aotus nancymae monkeys were also injected with G207 intraprostatically and observed short term (up to 21 days) and long term (56 days). Safety was assessed on the basis of clinical observations, viral biodistribution, virus shedding, and histopathology. None of the injected monkeys displayed evidence of clinical disease, shedding of infectious virus, or spread of the virus into other organs. Except for minor histological changes unrelated to the study, no significant abnormalities were observed. These results demonstrate that G207 can be safely inoculated into the prostate and should be considered for human trials for the treatment of prostate cancer.

Viral shedding and biodistribution of G207, a multimutated, conditionally replicating herpes simplex virus type 1, after intracerebral inoculation in aotus.

G207 is a multimutated, conditionally replicating herpes simplex virus type 1 (HSV-1) that is currently in clinical trial for patients with malignant glioma. G207 exhibits an efficient oncolytic activity in tumor cells, yet minimal toxicity in normal tissue when injected into the brains of HSV-susceptible mice or nonhuman primates. In this study, we evaluated the shedding and biodistribution of clinical-grade G207 after intracerebral inoculation (3 x 10(7) pfu) in four New World owl monkeys (Aotus nancymae). Using PCR analyses and viral cultures, neither infectious virus nor viral DNA was detected from tear, saliva, or vaginal secretion samples at any time point up to 1 month postinoculation. Analyses of tissues obtained at necropsy at 1 month from two of the four monkeys, plus one monkey inoculated with laboratory-grade G207 (10(9) pfu) 2 years earlier, showed the distribution of G207 DNA restricted to the brain, although infectious virus was not isolated. Histopathology revealed normal brain tissues including the sites of inoculation. A measurable increase of serum anti-HSV antibody titer was observed in all monkeys, as early as 21 days postinoculation. The results ascertain the safety of G207 in the brain and indicate that strict biohazard management may not be required for G207-treated patients.

The effect of sodium bicarbonate on propranolol-induced cardiovascular toxicity in a canine model.

STUDY OBJECTIVE: To evaluate the potential utility of sodium bicarbonate in an established model of acute propranolol toxicity. METHODS: Two minutes after the completion of a propranolol infusion (10 mg/kg), a bolus of 1.5 mEq/kg of sodium bicarbonate solution (1 mEq/mL) followed by an infusion of 1.5 mEq/kg over the next 26 minutes (n = 6) or an equivalent timing and volume of 5% dextrose solution (n = 6) was administered in each dog. Targeted cardiovascular parameters included heart rate, mean arterial pressure, left ventricular dP/dtmax, and QRS interval. RESULTS: Propranolol infusion significantly depressed heart rate (p < 0.0001), mean arterial pressure (p < 0.0001), dP/dtmax (p < 0.0001) and prolonged the QRS interval (p < 0.0001). Sodium bicarbonate failed to significantly improve these targeted parameters when compared to control animals. CONCLUSION: In this canine model of propranolol toxicity, intravenous sodium bicarbonate appears to be an ineffective single therapy. Furthermore, these results may suggest a different mechanism of sodium channel blockade for propanolol than that of type IA antiarrhythmic agents.

Attenuated, replication-competent herpes simplex virus type 1 mutant G207: safety evaluation of intracerebral injection in nonhuman primates.

This study examined the safety of intracerebral inoculation of G207, an attenuated, replication-competent herpes simplex virus type 1 (HSV-1) recombinant, in nonhuman primates. Sixteen New World owl monkeys (Aotus nancymae [karyotype 1, formerly believed to be A. trivirgatus]), known for their exquisite susceptibility to HSV-1 infection, were evaluated. Thirteen underwent intracerebral inoculation with G207 at doses of 10(7) or 10(9) PFU, two were vehicle inoculated, and one served as an infected wild-type control and received 10(3) PFU of HSV-1 strain F. HSV-1 strain F caused rapid mortality and symptoms consistent with HSV encephalitis, including fever, hemiparesis, meningitis, and hemorrhage in the basal ganglia. One year after G207 inoculation, seven of the animals were alive and exhibited no evidence of clinical complications. Three deaths resulted from nonneurologic causes unrelated to HSV infection, and three animals were sacrificed for histopathologic examination. Two animals were reinoculated with G207 (10(7) PFU) at the same stereotactic coordinates 1 year after the initial G207 inoculation. These animals were alive and healthy 2 years after the second inoculation. Cerebral magnetic resonance imaging studies performed both before and after G207 inoculation failed to reveal radiographic evidence of HSV-related sequelae. Despite the lack of outwardly observable HSV pathology, measurable increases in serum anti-HSV titers were detected. Histopathological examination of multiple organ tissues found no evidence of HSV-induced histopathology or dissemination. We conclude that intracerebral inoculation of up to 10(9) PFU of G207, well above the efficacious dose in mouse tumor studies, is safe and therefore appropriate for human clinical trials.

Control of negative inotropic vagal preganglionic neurons in the dog: synaptic interactions with substance P afferent terminals in the nucleus ambiguus?

Previous research from this laboratory has shown that substance P-immunoreactive (SP) terminals synapse upon negative chronotropic vagal preganglionic neurons (VPNs), but not upon negative dromotropic VPNs, of the ventrolateral nucleus ambiguus (NA-VL). Moreover, SP agonists injected into NA-VL cause bradycardia without decreasing AV conduction. In the current study, we have: (1) defined the electron microscopic characteristics of the SP neurons of NA-VL in dog; and (2) tested the hypothesis that SP nerve terminals synapse upon negative inotropic VPNs of NA-VL, retrogradely labeled from the cranial medial ventricular (CMV) ganglion. Numerous SP terminals and a few SP neurons were observed in the vicinity of retrogradely labeled neurons. SP terminals were observed forming synapses with unlabeled dendrites and with SP dendrites, but never with the retrogradely labeled neurons. Together, these results and earlier findings suggest that SP agonists may be able to induce bradycardia without decreasing AV conduction or ventricular contractility.

Up-regulation of two Candida albicans genes in the rat model of oral candidiasis detected by differential display.

Candida albicans is an opportunistic fungal pathogen responsible for the largest percentage of fungal-mediated oral and oesophageal disease. In this regard, knowledge concerning patterns of gene expression during the establishment and/or maintenance of infection may be the key to the design of new strategies for treatment, as well as providing insight into pathogenesis. To address this issue, experiments were performed that utilized differential display to compare the spectrum of C. albicans genes expressed during oral infection versus growth in in vitroculture. Experimentally, the rat model of oral candidiasis served as the in vivo source. After initiation of infection and subsequent harvesting of C. albicans from the rat oral cavity, RNA was isolated, and used with a small number of primers in reverse-transcriptase polymerase chain reaction (RT-PCR) and differential display experiments. Fragments unique to in vivo samples were subcloned and sequenced. Southern blot analysis verified the origin of seven fragments as fromC. albicans. Additionally, specific RT-PCR confirmed that two of these fragments represented genes that were up-regulated during C. albicans in vivo growth in the rat model. Database searches indicated the fragments share homology with a member of the C. albicans agglutinin gene family and to a bacterial gene (gidB) possibly involved in cell division.

Neural control of left ventricular contractility in the dog heart: synaptic interactions of negative inotropic vagal preganglionic neurons in the nucleus ambiguus with tyrosine hydroxylase immunoreactive terminals.

Recent physiological evidence indicates that vagal postganglionic control of left ventricular contractility is mediated by neurons found in a ventricular epicardial fat pad ganglion. In the dog this region has been referred to as the cranial medial ventricular (CMV) ganglion [J.L. Ardell, Structure and function of mammalian intrinsic cardiac neurons, in: J.A. Armour, J.L. Ardell (Eds.). Neurocardiology, Oxford Univ. Press, New York, 1994, pp. 95-114; B.X. Yuan, J.L. Ardell, D.A. Hopkins, A.M. Losier, J.A. Armour, Gross and microscopic anatomy of the canine intrinsic cardiac nervous system, Anat. Rec., 239 (1994) 75-87]. Since activation of the vagal neuronal input to the CMV ganglion reduces left ventricular contractility without influencing cardiac rate or AV conduction, this ganglion contains a functionally selective pool of negative inotropic parasympathetic postganglionic neurons. In the present report we have defined the light microscopic distribution of preganglionic negative inotropic neurons in the CNS which are retrogradely labeled from the CMV ganglion. Some tissues were also processed for the simultaneous immunocytochemical visualization of tyrosine hydroxylase (TH: a marker for catecholaminergic neurons) and examined with both light microscopic and electron microscopic methods. Histochemically visualized neurons were observed in a long slender column in the ventrolateral nucleus ambiguus (NA-VL). The greatest number of retrogradely labeled neurons were observed just rostral to the level of the area postrema. TH perikarya and dendrites were commonly observed interspersed with vagal motoneurons in the NA-VL. TH nerve terminals formed axo-dendritic synapses upon negative inotropic vagal motoneurons, however the origin of these terminals remains to be determined. We conclude that synaptic interactions exist which would permit the parasympathetic preganglionic vagal control of left ventricular contractility to be modulated monosynaptically by catecholaminergic afferents to the NA-VL.

Host response to multiple skin lacerations on the albino guinea pig.

Investigators have studied methods of treating skin lacerations by placing multiple incisions on each albino guinea pig. Theoretically, host responses to laceration sites may differ on the basis of anatomic location and local cytokine effects. We used cytokine values and histologic examination to identify differences when multiple lacerations were placed on each animal. Four 3-cm lacerations were made on the dorsum of each male albino guinea pig: two incisions on either side and parallel to the spine. Each laceration was closed with staples. In five animals a sponge technique was used to assay wound cytokines 48 h later. In an additional four animals, wounds were excised at 96 h and stained for cells and new collagen. We identified no statistically significant differences among laceration sites based on polymorphonuclear and mononuclear cellularity, number of fibroblasts, new collagen deposition, or wound interleukin (IL)-6 activities. Using this model minimizes the number of animals needed to generate statistically significant findings in wound research.

The diagnosis of acute pyelonephritis in the piglet using single photon emission computerized tomography dimercaptosuccinic acid scintigraphy: a pathological correlation.

Single photon emission computerized tomography (SPECT) scintigraphy has proved to be an extremely sensitive renal imaging modality in children with genitourinary pathology, including pyelonephritis, particularly when compared to 2-dimensional planar imaging. This study was undertaken to corroborate SPECT dimercaptosuccinic acid (DMSA) scintigraphic findings with specific histopathology in acute pyelonephritis. Unilateral vesicoureteral reflux was produced in 19 Yorkshire piglets 3 to 4 weeks old. The bladders of 12 animals were inoculated with Escherichia coli 2 weeks later, after baseline SPECT DMSA scans had been obtained. The animals were then re-imaged at 3 (4), 7 (4) or 14 (4) days after infection and sacrificed for histological evaluation. Seven purposefully uninfected piglets with unilateral reflux served as controls and were followed for up to 6 weeks before imaging and sacrifice. SPECT proved to be 97% sensitive and 93% specific in providing the diagnosis of acute pyelonephritis. The SPECT findings were manifest by a spectrum of abnormal findings (mottling, striations, inner cortical scalloping and focal cortical defects), which correlated precisely with the extent and severity of cortical involvement in the acute pyelonephritic process. We propose a new classification scheme for SPECT DMSA renal scintigraphic imaging, and believe that this modality is exquisitely sensitive in providing the diagnosis as well as in evaluating the extent of renal parenchymal involvement when acute pyelonephritis is induced in the animal model.

Evaluation of a prototype steerable angioscopic laser catheter in a canine model: a feasibility study.

To overcome some of the persisting technical problems related to laser angioplasty, a new catheter was designed and investigated in a canine model. This 5F catheter contained a deflectable tip for steerability, an angioscope, and a laser fiber. Catheter steerability, angioscopic function, and the effects of a 480 nm flash lamp pumped pulsed dye laser on normal canine vessel walls were evaluated. Steering, angioscopic guidance, and application of laser energy were easy and fast to perform in a bloodless vessel segment. Maintaining a condition of bloodlessness at the target site, critical to angioscopic guidance, proved to be the most difficult part in this prototype evaluation. It was noted that the 480 nm pulsed dye laser did not cause macroscopic alterations or perforations to the normal vessel wall. We conclude that a relatively simple deflection mechanism of a small-caliber angioscope provides the kind of aiming ability requisite for precise endovascular therapy. Complete bloodlessness of the area is necessary for both viewing and laser ablation at 480 nm.

Lack of protective effect of thromboxane synthetase inhibitor (CGS-13080) on single dose radiated canine intestine.

The effect of a thromboxane A2 synthetase inhibitor (CGS-13080) on canine intestine was studied using a single dose of radiation, and radioactive microspheres were used to determine resultant blood flow. Thromboxane A2 causes vasospasm and platelet aggregation and may play a dominant role in radiation injury. However, there was no effect on the intestinal blood flow diminution occurring after radiation in this laboratory model using this thromboxane A2 synthetase inhibitor.