Sheldon A. Steinberg

Glycogen Storage Disease Type IV: Inherited Deficiency of Branching Enzyme Activity in Cats

ABSTRACT: Glycogen storage disease type IV due to branching enzyme deficiency was found in an inbred family of Norwegian forest cats, an uncommon breed of domestic cats. Skeletal muscle, heart, and CNS degeneration were clinically apparent and histologically evident in affected cats older than 5 mo of age, but cirrhosis and hepatic failure, hallmarks of the human disorder, were absent. Beginning at or before birth, affected cats accumulated an abnormal glycogen in many tissues that was determined by histochemical, enzymatic, and spectral analysis to be a poorly branched α-1,4-D-glucan. Branching enzyme activity was less than 0.1 of normal in liver and muscle of affected cats and partially deficient (0.17–0.75 of normal) in muscle and leukocytes of the parents of affected cats. These data and pedigree analysis indicate that branching enzyme deficiency is a simple autosomal recessive trait in this family. This is the first reported animal model of human glycogen storage disease type IV. A breeding colony derived from a relative of the affected cats has been established.

Myotonia in a Horse

Congenital myotonia, similar to that which has been reported in humans and in goats, is here reported for the first time in another species. Evidence is given to show (i) that the myotonic phenomenon is present despite complete block of neuromuscular transmission; (ii) prior to injection of curare, synchronous activity of muscle fibers may result not only from ephaptic stimulation of neighboring fibers but also from reflex firing; and (iii) water deprivation does not relieve the myotonia.

A case of canine central nervous system cryptococcosis: management with fluconazole

A three-year-old, female Labrador retriever was presented for acute generalized seizures. Disseminated cryptococcosis with central nervous system (CNS) involvement was diagnosed by serum and cerebrospinal fluid (CSF) fungal titers, histopathological examination, and magnetic resonance imaging (MRI). Fluconazole therapy resulted in prolonged, substantial clinical improvement for a period of one year. This report documents the diagnosis of a case of cryptococcal meningoencephalitis and its management with the new antifungal agent, fluconazole.

A modified bilateral transfrontal sinus approach to the canine frontal lobe and olfactory bulb: Surgical technique and five cases

Five adult dogs presented for an acute onset of seizure activity. Magnetic resonance imaging revealed lesions in the olfactory bulbs, frontal lobes of the cerebrum, or both. A modified bilateral transfrontal sinus craniotomy was performed on each patient. The goal of removing the lesion was to relieve clinical signs and to provide tissue for histopathological diagnosis. In each instance, excision of the lesion was possible using this approach. No postoperative complications were observed. The modified bilateral transfrontal sinus craniotomy provides excellent access to the canine olfactory bulbs and frontal lobes.

The relationship between genetic deafness and fear-related behaviors in nervous pointer dogs

Nervous pointer dogs have been extensively characterized as an animal model for some human pathological anxiety states. During our work with these animals suspicion developed that some of these dogs had a hearing deficit. We decided to systematically evaluate this observation and to study the relation between hearing status and fear-related behaviors in the nervous pointer dogs. Our results revealed that a majority of the nervous dogs in our colony (75%) suffer from bilateral deafness as demonstrated by complete absence of brain stem auditory evoked response. Furthermore, behavioral ratings revealed that hearing and deaf dogs do not differ in their pathological response to the characteristic fear-provoking stimuli (e.g., human interaction) and that both hearing and deaf nervous dogs markedly differ from normal dogs in that respect. The relation between these abnormalities and their implications for research involving breeding of animals for selected traits are further discussed in this report.

A MYASTHENIC SYNDROME IN THE DOG: A CASE REPORT WITH ELECTRON MICROSCOPIC OBSERVATIONS ON MOTOR END PLATES AND COMPARISONS WITH THE FINE STRUCTURE OF END PLATES IN MYASTHENIA GRAVIS*

Although long regarded as a disease entirely limited to man, myasthenia gravis finds clinical parallel in rare cases of myasthenia in infrahuman species. Two case of myasthenic syndromes in dogs have been reported since 1961. In both of these instances, dogs suffered from myasthenic weakness which was improved promptly b y anticholinesterase medication. 1Jnfortunately, both cases lacked electromyographic or pathologic investigation of the animals. The purpose of the present report is to record a third instance of spontaneously occurring myasthenia in a dog tha t has been documented with preliminary electromyographic and pathologic studies of the muscle and the neuromuscular junction. Electron microscopic examination of intercostal motor end plates is presented and some comparisons with human motor end plates in myasthenia gravis are made.

Myxoid Meningiomas of the Rostral Cervical Spinal Cord and Caudal Fossa in Four Dogs

Reports of neoplasms of the spinal cord, meninges, and surrounding tissues in the dog are rare. Primary spinal meningeal tumors reported in the dog include meningeal sarcomas, lymphoma, typical meningiomas similar to those seen in the cranial cavity, and an atypical histiocytic meningioma in the midcervical area. There are also several reports of meningeal and vertebral involvement with nerve sheath tumors (Schwannomas, neurilemmomas, neurofibrosarcomas), malignant histiocytosis, primary bone sarcomas, and metastatic neoplasms. We report on four dogs with primary meningeal neoplasms of the dorsal rostral cervical spinal cord and caudal fossa that are morphologically distinct from the previously reported tumors of the meninges in the dog.

Inner ear histopathology in nervous Pointer dogs with severe hearing loss

Ten puppy dogs (82, 131 or 148 days-old) from a Pointer cross-colony, exhibiting a juvenile severe hearing loss transmitted as an autosomal recessive trait, were used for histopathological characterization of the inner ear lesion. Immunostaining with calbindin, Na,K-ATPase, cytokeratins, S100, S100A1 and S100A6 antisera were helpful in identifying the different cell types in the degenerated cochleae. Lesions, restricted to the Cortis organ and spiral ganglion, were bilateral but sometimes slightly asymmetrical. Mild to severe lesions of the Cortis organ were unevenly distributed among the different parts of the middle and basal cochlear turns while the apical turn remained unaffected at 148 days. In 82 day-old puppies (n = 2), severe lesions of the Cortis organ, meaning that it was replaced by a layer of unidentifiable cells, involved the lower middle and upper basal turns junction area, extending in the upper basal turn. Mild lesions of the Cortis organ, with both hair and supporting cells abnormalities, involved the lower middle turn and extended from the rest of upper basal turn into the lower basal turn. The outer hair cells (ohc) were more affected than the inner hair cell (ihc). The lesions extended towards the basal end of the cochlea in the 131 (n = 5) and 148 (n = 3) day-old puppies. Additionally, the number of spiral ganglion neurons was reduced in the 131 and 148 day-old puppies; it is earlier than observed in most other canine hereditary deafness. These lesions were interpreted as a degeneration of the neuroepithelial type. This possible animal model might provide information about progressive juvenile hereditary deafness and neuronal retrograde degeneration investigations in human.

Dynamic light scattering as an objective noninvasive method in veterinary ophthalmic diagnosis and research

The absence of verbal feedback, available from most human patients, is a major limitation in veterinary diagnosis in general and in the evaluation of ophthalmic lens opacity in particular. A novel compact dynamic light scattering (DLS) instrument, developed at NASA, offers significant mitigation to this limitation. It not only yields objective repeatable non-invasive estimation of lens opacity but also provides insight into the nature of chemical and physical alternations in the lens and other eye structures. For example, DLS measurements of the cataractous lens may be interpreted in terms of alpha crystalline protein size. In contrast to most conventional methods, the examination results are numerical and readily accommodate statistical analysis. We present results of DLS measurements in laboratory rabbits with naphthalene induced cataracts, rodents with genetically conditioned hypertension and/or diabetes mellitus; as well as applications of the DLS method in clinical veterinary patients. Use of DLS in examination of phacoemulsification fluid, urine and other biological materials, and potential applications in ocular toxically will also be discussed.