AAV gene transfer delays disease onset in a TPP1-deficient canine model of the late infantile form of Batten disease.

The most common form of the childhood neurodegenerative disease late infantile neuronal ceroid lipofuscinosis (also called Batten disease) is caused by deficiency of the soluble lysosomal enzyme tripeptidyl peptidase 1 (TPP1) resulting from mutations in the TPP1 gene. We tested whether TPP1 gene transfer to the ependyma, the epithelial lining of the brain ventricular system, in TPP1-deficient dogs would be therapeutically beneficial. A one-time administration of recombinant adeno-associated virus (rAAV) expressing canine TPP1 (rAAV.caTPP1) resulted in high expression of TPP1 predominantly in ependymal cells and secretion of the enzyme into the cerebrospinal fluid leading to clinical benefit. Diseased dogs treated with rAAV.caTPP1 showed delays in onset of clinical signs and disease progression, protection from cognitive decline, and extension of life span. By immunostaining and enzyme assay, recombinant protein was evident throughout the brain and spinal cord, with correction of the neuropathology characteristic of the disease. This study in a naturally occurring canine model of TPP1 deficiency highlights the utility of AAV transduction of ventricular lining cells to accomplish stable secretion of recombinant protein for broad distribution in the central nervous system and therapeutic benefit.

Enzyme replacement therapy attenuates disease progression in a canine model of late-infantile neuronal ceroid lipofuscinosis (CLN2 disease).

Using a canine model of classical late-infantile neuronal ceroid lipofuscinosis (CLN2 disease), a study was conducted to evaluate the potential pharmacological activity of recombinant human tripeptidyl peptidase-1 (rhTPP1) enzyme replacement therapy administered directly to the cerebrospinal fluid (CSF). CLN2 disease is a hereditary neurodegenerative disorder resulting from mutations in CLN2, which encodes the soluble lysosomal enzyme tripeptidyl peptidase-1 (TPP1). Infants with mutations in both CLN2 alleles develop normally but in the late-infantile/early-childhood period undergo progressive neurological decline accompanied by pronounced brain atrophy. The disorder, a form of Batten disease, is uniformly fatal, with clinical signs starting between 2 and 4 years of age and death usually occurring by the early teenage years. Dachshunds homozygous for a null mutation in the canine ortholog of CLN2 (TPP1) exhibit a similar disorder that progresses to end stage at 10.5-11 months of age. Administration of rhTPP1 via infusion into the CSF every other week, starting at approximately 2.5 months of age, resulted in dose-dependent significant delays in disease progression, as measured by delayed onset of neurologic deficits, improved performance on a cognitive function test, reduced brain atrophy, and increased life span. Based on these findings, a clinical study evaluating the potential therapeutic value of rhTPP1 administration into the CSF of children with CLN2 disease has been initiated.

Description and validation of a magnetic resonance imaging-guided stereotactic brain biopsy device in the dog.

A stereotactic brain biopsy system that is magnetic resonance (MR) imaging-guided has not been validated in dogs. Our purpose was to determine the mean needle placement error in the caudate nucleus, thalamus, and midbrain of a canine cadaver brain using the modified Brainsight stereotactic system. Relocatable reference markers (fiducial markers) were attached to the cadaver head using a dental bite block. A T1-weighted gradient echo three-dimensional (3D) sequence was acquired using set parameters. Fiducial markers were used to register the head to the acquired MR images in reference to a 3D position sensor. This allowed the planning of trajectory path to brain targets in real time. Coordinates (X, Y, Z) were established for each target and 0.5 microl of diluted gadolinium was injected at each target using a 26-gauge needle to create a lesion. The center of the gadolinium deposition was identified on the postoperative MR images and coordinates (X', Y', Z') were established. The precision of this system in bringing the needle to target (needle placement error) was calculated. Seventeen sites were targeted in the brain. The mean needle placement error for all target sites was 1.79 +/- 0.87 mm. The upper bound of error for this stereotactic system was 3.31 mm. There was no statistically significant relationship between needle placement error and target depth (P = 0.23). The ease of use and precision of this stereotactic system support its development for clinical use in dogs with brain lesions > 3.31 mm.

A truncating mutation in ATP13A2 is responsible for adult-onset neuronal ceroid lipofuscinosis in Tibetan terriers.

A recessive, adult-onset neuronal ceroid-lipofuscinosis (NCL) occurs in Tibetan terriers. A genome-wide association study restricted this NCL locus to a 1.3Mb region of canine chromosome 2 which contains canine ATP13A2. NCL-affected dogs were homozygous for a single-base deletion in ATP13A2, predicted to produce a frameshift and premature termination codon. Homozygous truncating mutations in human ATP13A2 have been shown by others to cause Kufor-Rakeb syndrome (KRS), a rare neurodegenerative disease. These findings suggest that KRS is also an NCL, although analysis of KRS brain tissue will be needed to confirm this prediction. Generalized brain atrophy, behavioral changes, and cognitive decline occur in both people and dogs with ATP13A2 mutations; however, other clinical features differ between the species. For example, Tibetan terriers with NCL develop cerebellar ataxia not reported in KRS patients and KRS patients exhibit parkinsonism and pyramidal dysfunction not observed in affected Tibetan terriers. To see if ATP13A2 mutations could be responsible for some cases of human adult-onset NCL (Kufs disease), we resequenced ATP13A2 from 28 Kufs disease patients. None of these patients had ATP13A2 sequence variants likely to be causal for their disease, suggesting that mutations in this gene are not common causes of Kufs disease.

Canine degenerative myelopathy.

Canine degenerative myelopathy (DM) is an adult-onset fatal neurodegenerative disease that occurs in many breeds. The initial upper motor neuron spastic paraparesis and general proprioceptive ataxia in the pelvic limbs progress to a flaccid lower motor neuron tetraparesis. Recently, a missense mutation in the superoxide dismutase 1 (SOD1) gene was found to be a risk factor for DM, suggesting that DM is similar to some forms of human amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease). This article reviews the current knowledge of canine DM with regard to its signalment, clinical spectrum, diagnostic approach, and treatment. The implications of the SOD1 mutation on both diseases are discussed, comparing pathogenic mechanisms while conveying perspectives to translational medicine.

Gamma-irradiated Calvarium Allograft Cranioplasty in a cat following brain tumor removal.

A 14-year-old domestic shorthair cat was evaluated for a 3-month history of head pressing and circling. Neurological examination suggested a supratentorial problem, predominantly on the left side. An extradural mass extending from the rostral frontal lobes caudally to the level of the caudal aspect of the corpus callosum was found with magnetic resonance imaging. A bilateral rostrotentorial craniectomy combined with a frontal sinus craniectomy was performed for mass removal. A gamma-irradiated calvarial allograft was used to repair the calvarial defect. At 14 months following surgery, the cat had no neurological abnormalities, and the skull and facial appearance was normal.

In vitro biomechanical evaluations of screw-bar-polymethylmethacrylate and pin-polymethylmethacrylate internal fixation implants used to stabilize the vertebral motion unit of the fourth and fifth cervical vertebrae in vertebral column specimens from dogs.

OBJECTIVE: To determine the change in stiffness as evaluated by the dorsal bending moment of cervical vertebral specimens obtained from canine cadavers after internally stabilizing the vertebral motion unit (VMU) of C4 and C5 with a traditional pin-polymethylmethacrylate (PMMA) fixation implant or a novel screw-bar-PMMA fixation implant. SAMPLE POPULATION: 12 vertebral column specimens (C3 through C6) obtained from canine cadavers. PROCEDURES: A dorsal bending moment was applied to the vertebral specimens before and after fixation of the VMU of C4 and C5 by use of a traditional pin-PMMA implant or a novel screw-bar-PMMA implant. Biomechanical data were collected and compared within a specimen (unaltered vs treated) and between treatment groups. Additionally, implant placement was evaluated after biomechanical testing to screen for penetration of the transverse foramen or vertebral canal by the pins or screws. RESULTS: Treated vertebral specimens were significantly stiffer than unaltered specimens. There was no significant difference in stiffness between vertebral specimen groups after treatment. None of the screws in the novel screw-bar-PMMA implant group penetrated the transverse foramen or vertebral canal, whereas there was mild to severe penetration for 22 of 24 (92%) pins in the traditional pin-PMMA implant group. CONCLUSIONS AND CLINICAL RELEVANCE: Both fixation treatments altered the biomechanical properties of the cervical vertebral specimens as evaluated by the dorsal bending moment. There was reduced incidence of penetration of the transverse foramen or vertebral canal with the novel screw-bar-PMMA implant, compared with the incidence for the traditional pin-PMMA implant.

Complete optical neurophysiology: toward optical stimulation and recording of neural tissue.

Direct optical methods to stimulate and record neural activity provide artifact-free, noninvasive, and noncontact neurophysiological procedures. For stimulation, focused mid-infrared light alters membrane potential and activates individual neural processes. Simultaneous intrinsic scattered light parameters, including birefringence changes, can record neural activity with signals similar to potentiometric dyes. The simultaneous combination of optical stimulation and optical recording techniques provide the potential for powerful tools that may someday remove the need for invasive wires during electrophysiological recordings.

Relationship between Doppler blood pressure and survival or response to treatment in critically ill cats: 83 cases (2003-2004).

OBJECTIVE: To evaluate the relationship between Doppler blood pressure (DBP) and survival or response to treatment in critically ill cats. DESIGN: Retrospective case series. ANIMALS: 83 cats. PROCEDURES: Medical records from cats admitted to the intensive care unit with at least 2 recorded DBP measurements were included in the study. Hypotension was defined as 1 or more DBP measurements d 90 mm Hg. Change in blood pressure, survival to hospital discharge, heart rate, rectal temperature, PCV, plasma pH, serum ionized calcium concentration, disease process, body weight, age, duration of hospitalization, and catecholamine treatment were also evaluated. RESULTS: 39 cats were included in the hypotensive group, and 44 were consistently normotensive. Overall survival rate was 53% (44/83), with a significantly higher mortality rate in the hypotensive group (64% vs 32%). Among other variables, only low rectal temperature and low PCV were significantly associated with hypotension. Hypotensive cats with an increase in blood pressure of >or=20 mm Hg during hospitalization were more likely to survive to discharge (mortality rate, 69% vs 17%). CONCLUSIONS AND CLINICAL RELEVANCE: Hypotensive cats had increased mortality rate with lower rectal temperatures and lower PCV, compared with normotensive critically ill cats. The implications of these findings with regard to treatment remain to be elucidated, but addressing these abnormalities may be appropriate.

Failure mode and bending moment of canine pancarpal arthrodesis constructs stabilized with two different implant systems.

OBJECTIVE: To compare failure mode and bending moment of a canine pancarpal arthrodesis construct using either a 2.7 mm/3.5 mm hybrid dynamic compression plate (HDCP) or a 3.5 mm dynamic compression plate (DCP). STUDY DESIGN: Paired in vitro biomechanical testing of canine pancarpal arthrodesis constructs stabilized with either a 2.7/3.5 HDCP or 3.5 DCP. SAMPLE POPULATION: Paired cadaveric canine antebrachii (n=5). METHODS: Pancarpal arthrodesis constructs were loaded to failure (point of maximum load) in 4-point bending using a materials-testing machine. Using this point of failure, bending moments were calculated from system variables for each construct and the 2 plating systems compared using a paired t-test. To examine the relationship between metacarpal diameter and screw diameter failure loads, linear regression was used and Pearson' correlation coefficient was calculated. Significance was set at P<.05. RESULTS: HDCP failed at higher loads than DCP for 9 of 10 constructs. The absolute difference in failure rates between the 2 plates was 0.552+/-0.182 N m, P=.0144 (95% confidence interval: -0.58 to 1.68). This is an 8.1% mean difference in bending strength. There was a significant linear correlation r=0.74 (P-slope=.014) and 0.8 (P-slope=.006) between metacarpal diameter and failure loads for the HDCP and 3.5 DCP, respectively. CONCLUSION: There was a small but significant difference between bending moment at failure between 2.7/3.5 HDCP and 3.5 DCP constructs; however, the difference may not be clinically evident in all patients. CLINICAL RELEVANCE: The 2.7/3.5 HDCP has physical and mechanical properties making it a more desirable plate for pancarpal arthrodesis.