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Biomedical subjects

J F Cummings

Publications and source records attributed to J F Cummings.

At least 91 records · Page 5Linked to original sources
PubMed1982

An enzyme tracer study of the organization of the somatic motor center for the innervation of different muscles of the tongue: evidence for two sources.

The hypoglossal nucleus has been described as the sole ipsilateral source of somatic motor innervation of the lingual and geniohyoideus muscles (Streeter, '40; Barnard, '40; Crosby et al., '62; Watkins, '78; Jenkins, '78). In this study microliter amounts of 30% solution of horseradish peroxidase (HRP) were injected into intact but surgically isolated canine genioglossus, hyoglossus, styloglossus, geniohyoideus, and intrinsic lingual muscles. All injections were confined to the left half of the tongue, and the right half served as control. The HRP injections resulted in ipsilateral labeling of hypoglossal neurons with the exception of the injections into the genioglossus muscle, which labeled this nucleus bilaterally. Surprisingly, a few neurons associated with the ventromedial aspect of the caudal pole of the ipsilateral facial motor nucleus also labeled after injections of lingual muscles. The somatotopic representation of the geniohyoideus and lingual muscles within the hypoglossal nucleus suggested that those muscles known to originate from the same or related primodia labeled in the same or closely related hypoglossal subnuclei. The presence of labeled neurons associated with facial motor nucleus supported the hypothesis (Langman, '75) of a possible dual origin of lingual muscles.

Animals↗
PubMed1982

Coonhound paralysis. Further clinical studies and electron microscopic observations.

Prior study of coonhound paralysis (CHP) revealed an acute polyradiculoneuritis in raccoon-hunting dogs with clinical and pathologic features resembling those of Guillain-Barré syndrome (GBS). In the present series of five cases, the clinical features were investigated with emphasis on electrodiagnostic and CSF findings, and pathologic changes were evaluated with both the light and electron microscope. The demonstration of motor nerve conduction delay and CSF albuminocytologic dissociation in affected dogs further supported the clinical similarity of CHP and GBS. As in GBS, affected roots and nerves contained mononuclear cell infiltrates, segmental myelin changes and axon degeneration. Despite these general pathologic similarities, the present study suggested that axon damage was a more consistent finding in CHP than in GBS. In contrast to ultrastructural findings in GBS, the demyelinating process in CHP did not appear dependent upon macrophages for its initiation. Swelling, separation and vesiculation of myelin occurred around axons of reduced diameter often in the absence of proximate macrophages. Macrophages, rather than initiating demyelination, appeared to be superimposed on existing damage. In this regard, the observed changes resembled those reported in galactocerebroside-induced EAN and sera-mediated in vivo demyelination.

Acute Disease↗
PubMed1981

The origins of the afferent fibers to the lingual muscles of the dog, a retrograde labelling study with horseradish peroxidase.

The origin of the afferent fibers to the lingual muscles of the dog was investigated by means of retrograde transport of horseradish peroxidase (HRP) from injection sites in the tongue and the extrinsic lingual muscles. Intralingual injections were not satisfactory because the enzyme diffused beyond the intrinsic lingual muscles to include virtually all tissues within the tongue. Thus, the resultant retrograde labeling of cell bodies of the trigeminal, geniculate, glossopharyngeal, vagal, and first cervical (C1) spinal ganglia represented a composite of lingual sensory innervation. In order to confine HRP uptake to intramuscular nerve endings, injections were limited to surgically isolated extrinsic lingual muscles, i.e., the genioglossus, hyoglossus, and styloglossus. After these intramuscular injections, labeled neurons appeared ipsilaterally in the C1 spinal ganglion, the proximal vagal (jugular) ganglion, and trigeminal ganglion. Earlier suggestions that the lingual proprioceptive neurons of the dog reside in the distal vagal (nodose) ganglion and hypoglossal ganglia were not confirmed. The mesencephalic nucleus of the trigeminal nerve failed to label after enzyme injections into the tongue or the extrinsic lingual muscles. The retrograde labeling of cell bodies in the C1 spinal ganglion was abolished when HRP injections into the extrinsic lingual muscles were preceded by surgical interruption of the ansa cervicalis or distal section of the hypoglossal nerve. Retrograde labeling of neurons in the proximal vagal ganglion persisted after hypoglossal nerve transections.

Afferent Pathways↗
PubMed1981

Canine inherited hypertrophic neuropathy.

A recessively inherited hypertrophic neuropathy was discovered in Tibetan Mastiff dogs. Affected pups developed a generalized weakness with hyporeflexia shortly after weaning. Diagnostic findings in 10-18-week-old pups included: moderate to severe reduction in nerve conduction velocities, infrequent denervation potentials, and inconstant elevation in CSF protein. Light- and electron-microscopic studies of peripheral nerves and roots revealed widespread demyelination and primitive onion bulb formation with relatively little degeneration of axons. Myelin changes often were most striking in the cytoplasmic regions of the sheaths and consisted of separations at the major dense lines, anomalous incisure patterns, and marked filamentous accumulations in the inner spirals and adaxonal cytoplasm. The results of these initial studies suggest an inborn defect in the Schwann cell's ability to form or maintain a stable myelin sheath.

Animals↗
PubMed1980

Motor and sensory centers for the innervation of mandibular and sublingual salivary glands: a horseradish peroxidase study in the dog.

Horeradish peroxidase was injected at multiple sites in the mandibular and sublingual salivary glands in order to label the preganglionic salivatory neurons in the brain stem. The same injections resulted in retrograde labeling of the sympathetic and sensory neurons that project to these glands. Labeled fusiform and multipolar salivatory neurons were found ipsilaterally in the lateral reticular formation of the medulla where they extended over the rostral four-fifths of the facial nucleus and the caudal one-third of the dorsal nucleus of the trapezoid body. The vast majority of the small and medium-sized, labeled neurons appeared in thally at the ventral and lateral aspects of the facial nucleus. Enzyme injections into these glands labeled sympathetic neurons that were concentrated in the caudal one-third of the ipsilateral cranial cervical ganglion. Labeled sensory neurons were distributed randomly in the ipsilateral proximal vagal and geniculate ganglia. Large numbers of sensory neurons were concentrated ventromedially within the mandibular zone of the trigeminal ganglion.

Animals↗
PubMed1980

Autonomic innervation of the tongue: a horseradish peroxidase study in the dog.

Autonomic ganglia have been found along the lingual nerve in the rostral two-thirds of the canine tongue and along the glossopharyngeal nerve in the caudal glandular third of the tongue [4,17,18]. A 30% horseradish peroxidase (HRP) solution was injected throughout these ganglionated areas in order to identify the origin of the preganglionic fibers to the lingual ganglia. These injections resulted in ipsilateral retrograde labeling of small multipolar neurons in the lateral reticular formation of the medulla oblongata. The same injections labeled neurons in the ipsilateral cranial cervical ganglion, but preganglionic sympathetic neurons in the thoracic spinal cord were not labeled. These findings indicated that the lingual ganglia consist of parasympathetic neurons which receive preganglionic projections from the medulla. The lingual preganglionic neurons were located within the nucleus reticularis parvicellularis and, in this location, were co-extensive with salivatory neurons that labeled after HRP injections in the mandibular and sublingual salivary glands. A degree of somatotopic organization within the lingual preganglionic group was indicated by the results of regional injections of enzyme and was confirmed by performing unilateral chorda tympani and glossopharyngeal neurectomies prior to extensive bilateral injections of HRP.

Animals↗
PubMed1979

Neuritis of the cauda equina, a chronic idiopathic polyradiculoneuritis in the horse.

Four cases of neuritis of the cauda equina (NCE) were studied by light and electron microscopy. Examination of sacral intradural rootlets revealed inflammatory cell infiltrates and an array of myelinated fiber changes which included myelin stripping by invading mononuclear cells and macrophages, as well as splitting and vesiculation of myelin lamellae without obvious participation by leukocytes. More distally in the extradural roots, there was marked granulomatous inflammation, and demyelinative changes were overshadowed by widespread evidence of irreversible axon damage. In all cases, unusual crystalline inclusions appeared in the endoneurium and sheaths of the rootlets and fascicles. The changes in NCE were compared and contrasted with those observed in acute and chronic inflammatory demyelinative neuropathies.

Animals↗
PubMed1979

Experimental coonhound paralysis: animal model of Guillain-Barré syndrome.

Coonhound paralysis (CHP), a polyradiculoneuritis of dogs that resembles the human Guillain-Barré syndrome, was experimentally reproduced by inoculating a dog with raccoon saliva. The test animal was a coonhound that had previously sustained two naturally occurring attacks of CHP. Success in inducing the disease strengthened the notion that raccoon saliva contains the etiologic factor for CHP and that only specifically susceptible dogs are at risk of developing CHP when exposed to this factor.

Animals↗
PubMed1979

Surgical procedure for exposure of the chorda tympani in dogs: a ventral approach.

An experimental neuroanatomic investigation of the innervation of the dog's tongue by the method of retrograde axonal transport of horseradish peroxidase required that chorda tympani neurectomy be performed in neonatal pups. Surgical exposure and transection of the chorda tympani proximal to its union with the lingual branch of the mandibular nerve in the past has been accomplished by radical lateral approach which is suited only for acute experimentation. This report describes a ventral surgical exposure of the extracranial portion of the chorda tympani in the dog. This surgical procedure permits long-term survival and is considered especially useful for the chronic neuroanatomic and neurophysiologic investigations on the role of the chorda tympany in taste, salivation and lingual vasodilation in the dog.

Animals↗
PubMed1978

Hereditary myelopathy of Afghan hounds, a myelinolytic disease.

A disease described previously as hereditary necrotizing myelopathy and myelomalacia was studied in four Afghan hounds. Light and electron microscopic investigation revealed sieve-like degeneration of spinal white matter. Despite extensive spongiform degeneration of myelin that progressed to micro- and macro-cavitation, substantial numbers of axons were preserved. This canine myelopathy was compared and contrasted with various toxic/metabolic conditions including subacute combined degeneration.

Animals↗
PubMed1977

An adult case of canine neuronal ceroid-lipofuscinosis.

Intraneuronal accumulation of cytosomes with the fluorescent and tinctorial properties of ceroidlipofuscin occurred in the C.N.S. of a fully matured dog with signs of slowly progressive cerebellar disease. Ultrastructural study revealed various membrane-bound inclusions in addition to typical lipofuscin granules. The clinicopathologic findings in this case were contrasted with those occurring in English Setters with juvenile neuronal ceroid-lipofuscinosis, and compared with those reported in Kufs' disease in man.

Adult↗