Mucopolysaccharidosis-like phenotype in feline Sandhoff disease and partial correction after AAV gene therapy.

Sandhoff disease (SD) is a fatal neurodegenerative disease caused by a mutation in the enzyme ß-N-acetylhexosaminidase. Children with infantile onset SD develop seizures, loss of motor tone and swallowing problems, eventually reaching a vegetative state with death typically by 4years of age. Other symptoms include vertebral gibbus and cardiac abnormalities strikingly similar to those of the mucopolysaccharidoses. Isolated fibroblasts from SD patients have impaired catabolism of glycosaminoglycans (GAGs). To evaluate mucopolysaccharidosis-like features of the feline SD model, we utilized radiography, MRI, echocardiography, histopathology and GAG quantification of both central nervous system and peripheral tissues/fluids. The feline SD model exhibits cardiac valvular and structural abnormalities, skeletal changes and spinal cord compression that are consistent with accumulation of GAGs, but are much less prominent than the severe neurologic disease that defines the humane endpoint (4.5±0.5months). Sixteen weeks after intracranial AAV gene therapy, GAG storage was cleared in the SD cat cerebral cortex and liver, but not in the heart, lung, skeletal muscle, kidney, spleen, pancreas, small intestine, skin, or urine. GAG storage worsens with time and therefore may become a significant source of pathology in humans whose lives are substantially lengthened by gene therapy or other novel treatments for the primary, neurologic disease.

Implantation of a titanium partial limb prosthesis in a white-naped crane (Grus vipio).

A female white-naped crane (Grus vipio) was presented with an open, oblique fracture of the distal right tarsometatarsus and concomitant vascular and nerve damage. Conventional fracture fixation repairs failed, which led to implantation of a custom titanium limb prosthesis. After subsequent revisions with 2 different prosthetic devices, limb function was ultimately restored but a later yolk embolism caused a circulatory compromise in the opposite leg, which necessitated euthanasia. Histopathologic results revealed limited ingrowth of bone into the porous coated implant, which indicated that a limb prosthesis may provide salvage for long-legged, heavy-bodied birds with fractures of the tarsometatarsus.

Laser illumination of flight crewmembers by altitude and chronology of occurrence.

INTRODUCTION: The illumination of flight crew personnel by lasers while they perform landing and departure maneuvers has concerned the aviation community for the past two decades. This study examines the frequency of illumination events in the United States by altitude and chronology of occurrence to determine where and when aviators and the flying public may be at greatest risk. METHODS: Reports of aircraft illuminated by high-intensity light sources are maintained in a database at the Federal Aviation Administration's Civil Aerospace Medical Institute. Reports of flight crewmembers exposed to lasers from January 1, 2004, to December 31, 2008, were collected and analyzed. RESULTS: Cockpit illuminations at or below 2000 ft (approximately 610 m) increased from 12.5 to 26.7% over the 5-yr period, while the percentage of illuminations between 2000 and 10,000 ft (approximately 610-3048 m) decreased from 87.5 to 58.4%. The months of November and December had the highest frequency of laser events (23%), while May and June had the least (12%). Sunday was the most likely day for an aircraft to be illuminated (18.3%), while Wednesday was the least likely day for such an incident (15.4%). More than 91% of all aircraft illumination events occurred between 1800 and midnight. CONCLUSION: The continuing increase in the number of laser illuminations reported at or below 2000 ft (approximately 610 m) represents an escalating threat to aviation safety. Information provided in this study may allow law enforcement to deploy their resources more efficiently to apprehend those responsible for these crimes.

Use of a locking compression plate as an external fixator for repair of a tarsometatarsal fracture in a bald eagle (Haliaeetus leucocephalus).

We describe the successful treatment of a tarsometatarsal fracture in a mature bald eagle (Haliaeetus leucocephalus) using a locking compression plate as an external fixator. The anatomy of the area (inelastic dermis and minimal subcutaneous space) and the high forces placed on a fracture at that site necessitated a unique approach to fixation. The unconventional use of a locking compression plate as an external fixator was minimally invasive, well tolerated by the eagle, and provided adequate stability in opposing fracture forces. This technique may serve as a method of fixation for tarsometatarsal fractures in other large avian species.

Aircraft accidents and incidents associated with visual effects from bright light exposures during low-light flight operations.

INTRODUCTION: Preservation of optimal night vision is important for pilots operating aircraft in low-light conditions. This study investigates operational problems experienced by civilian airmen exposed to bright light sources while performing nighttime aviation activities. METHODS: The National Transportation Safety Board (NTSB) Aviation Accident and Incident Data System and the Federal Aviation Administration (FAA) Accident/Incident Data System were queried using terms associated with night vision problems. Accident and incident reports annotated with 1 or more of these terms were reviewed to determine whether exposure to bright lights at night may have contributed to the mishap. RESULTS: Vision problems resulting from exposure to bright lights at night contributed to 58 mishaps. Reports included 30 (NTSB) accidents and 28 (FAA/NTSB) incidents. The majority of accidents (57%) occurred during the approach and landing phase of flight. Incidents occurred most frequently while taxiing (54%) and during approach and landing (36%). CONCLUSIONS: Exposure to bright light sources at night has contributed to aviation accidents and incidents. The information in this study may assist airport authorities in identifying and eliminating hazardous lighting near flight paths and surface movement areas. Preventive measures for avoiding conditions that compromise the safety of aviation operations at night are discussed.

Changing demographics and vision restrictions in civilian pilots and their clinical implications.

BACKGROUND: The Federal Aviation Administration guides policy decisions through the study of medical pathologies and visual disorders common to aviators. The purpose of this study is to examine demographic statistics present in the civil airman population, including vision restrictions, and their relevance to the clinical care of aviators. METHODS: Medical certification data were extracted from FAA publications and databases for all civil airmen who were active on December 31st of each year from 1976 to 2001. Frequency and medical restriction data were delineated into 5-yr increments and analyzed to identify population trends for the 25-yr study period. RESULTS: Although the total number of pilots has decreased over the study period (-17%), the population of male and female airmen holding first-class medical certificates has grown by 119% and 1,241%, respectively. The percentage of pilots > or = 40 yr of age has increased by 17%, and the average age rose from 36.8 to 42.3 yr. Additionally, the increase in near vision restrictions (13%) was more than double that of distant vision restrictions (6%) during the study period. As of 2001, 92% of all medical restrictions were vision related. CONCLUSION: The results of this study indicate that the increasing number of first-class certificate holders, gender-specific vision problems for female pilots, and the age-related changes in refractive error may present new challenges for eye-care practitioners tasked with advising aviators concerning the proper choice of refractive correction.

Pre- and postoperative force plate analysis of dogs with experimentally transected cranial cruciate ligaments treated using tibial plateau leveling osteotomy.

OBJECTIVE: Quantitative and objective assessment of hindlimb kinetics after cranial cruciate ligament (CrCL) transection and subsequent stifle stabilization using the tibial plateau leveling osteotomy (TPLO) in normal dogs. STUDY DESIGN: In vivo experimental biomechanical evaluation. ANIMALS: Six healthy adult foxhounds. METHODS: Dogs were screened by orthopedic and radiographic examination before study entry. Force plate analysis of gait was measured before extirpation of the right CrCL and TPLO and again at 8 and 18 weeks after surgery. RESULTS: There was a significant decrease in peak vertical forces (PVFs) and vertical impulse (VI) of the treated hindlimb at 8 weeks when compared with preoperative and 18-week measurements. When compared with preoperative values, there was no significant difference in 18 week PVF and VI in dogs that had TPLO. CONCLUSION: TPLO can restore kinetic measures of limb function at 18-weeks after surgery when compared with preoperative values after experimental transection of the CrCL in dogs. CLINICAL RELEVANCE: TPLO induces lameness that returns to near normal at 18 weeks. The severity and duration of lameness was similar to that reported for other experimental models of stifle instability repaired by different techniques.

Influence of dietary calcium and phosphorus content in a fixed ratio on growth and development in Great Danes.

OBJECTIVE: To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor 1 and parathyroid hormone concentrations, radiography, and blood chemistry analysis results. ANIMALS: 32 purebred Great Dane puppies from 4 litters. PROCEDURE: At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age. RESULTS: Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group. CONCLUSIONS AND CLINICAL RELEVANCE: Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age.

Evaluation of small-intestinal submucosa implants for repair of meniscal defects in dogs.

OBJECTIVE: To assess the effects of porcine small intestinal submucosa (SIS) implants on the healing of meniscal lesions in dogs. ANIMALS: 16 adult Greyhounds of both sexes. PROCEDURE: Unilateral osteotomy was performed at time 0 to disrupt the medial collateral ligament attachment, and two (1 cranial and 1 caudal) 4-mm circular defects were created in the avascular portion of the medial meniscus. One defect was filled with an SIS graft, and the other defect remained empty (control). Three months later, the identical procedure was performed on the contralateral limb. Three months after the second surgery, dogs were euthanatized, and meniscal tissue specimens from both stifle joints were collected for gross, histologic, biomechanical, and biochemical evaluations. RESULTS: Regenerative tissue was evident in 4 (2 SIS-implanted and 2 control) of 16 defects examined histologically. In 3 defects, this thin bridge of tissue was composed of immature haphazardly arranged fibrous connective tissue with a relatively uniform distribution of fibroblasts. Aggregate modulus, Poisson ratio, permeability, and shear modulus were not significantly different between control and SIS-implanted defects either 3 or 6 months after surgery. Hydroxyproline content also did not differ between SIS-implanted and control defects at 3 or 6 months. CONCLUSIONS AND CLINICAL RELEVANCE: Implantation of porcine SIS into experimentally induced meniscal lesions in dogs did not promote tissue regeneration.