Search PubMed⌕ Search

Biomedical subjects

J Keane

Publications and source records attributed to J Keane.

At least 37 records · Page 2Linked to original sources
PubMed1997

Distribution of motoneurons supplying feline neck muscles taking origin from the shoulder girdle.

A combination of fluorescent retrograde tracers and horseradish peroxidase (HRP) was used to compare the spinal distributions of motoneurons supplying shoulder muscles with attachments to the skull and cervical spinal cord that suggest a significant role in head movement. Two muscles, the rhomboideus and the levator scapulae, were innervated by multiple segmental nerve bundles that entered the muscles at different rostrocaudal locations. Motoneurons that were labelled retrogradely from rhomboideus nerve bundles formed a single, long column in the ventral horn from C4 to C6, lateral to previously studied motor nuclei supplying deep neck muscles. When different tracers were used to differentiate motoneurons supplying specific nerve bundles, discrete subnuclei could be identified that were organized in a rostrocaudal sequence corresponding to the rostrocaudal order of the nerve bundles. Levator scapulae motoneurons formed a second elongate column immediately lateral to the rhomboidues motor nucleus. Three other muscles, that trapezius, sternomastoideus, and cleidomastoideus, were supplied by cranial nerve XI. Labelled motoneurons from these muscles formed a single column from the spinomedullary junction to middle C6. Within this column, the three motor nuclei supplying the sternomastoideus, cleidomastoideus, and trapezius were laminated mediolaterally. Sternomastoideus and cleidomastoideus motoneurons were confined to upper cervical segments, whereas trapezius motoneurons were found from C1 to C6. In C1 and C6, the motoneuron column was located centrally in the gray matter, but, between C2 and C5, the column lay on the lateral wall of the ventral horn in a position dorsolateral to motor nuclei supplying the rhomboideus and the deeper neck muscles. The findings in this study suggest that descending and propriospinal systems responsible for coordinating head movement may have to descend as far caudally as C6 if they are to project onto muscles controlling the mobility of the lower neck.

Accessory Nerve↗
PubMed1997

Facial talon cusps.

This is a report of two patients with isolated facial talon cusps. One occurred on a permanent mandibular central incisor; the other on a permanent maxillary canine. The locations of these talon cusps suggests that the definition of a talon cusp include teeth in addition to the incisor group and be extended to include the facial aspect of teeth.

Adolescent↗
PubMed1997

Infection by Mycobacterium tuberculosis promotes human alveolar macrophage apoptosis.

The effect of Mycobacterium tuberculosis infection on the viability of healthy (control) human alveolar macrophages was evaluated by staining with ethidium homodimer and calcein to discriminate live from dead cells. Infection with M. tuberculosis H37Ra or H37Rv increased macrophage mortality at 6 days from the control level of 3.8% +/- 0.7% to 28.7% +/- 6.9% or 12.6% +/- 3.1%, respectively (P < 0.001 for comparisons of all conditions). A role for tumor necrosis factor alpha (TNF-alpha) in the M. tuberculosis-induced cytolysis of alveolar macrophages was demonstrated by increased cytotoxicity following the addition of exogenous TNF-alpha to the cultures and by enhancement of macrophage survival when M. tuberculosis-infected alveolar macrophages were treated with pentoxifylline or anti-TNF-alpha antibody. The cytolytic mechanism was determined to be apoptosis by the demonstration of a characteristic internucleosomal ladder of genomic DNA by agarose gel electrophoresis, by finding nuclear fragmentation and condensation by electron microscopy, and by in situ terminal transferase-mediated nick end labeling of fragmented DNA in alveolar macrophages infected with M. tuberculosis in vitro. The latter technique was employed to reveal extensive apoptosis within caseating granulomas from lung tissue samples from clinical tuberculosis cases. The induction of apoptosis in alveolar macrophages by M. tuberculosis may play a role in the macrophage-pathogen interaction of tuberculosis in vivo.

Apoptosis↗
PubMed1995

Targeted expression of tetanus toxin light chain in Drosophila specifically eliminates synaptic transmission and causes behavioral defects.

Tetanus toxin cleaves the synaptic vesicle protein synaptobrevin, and the ensuing loss of neurotransmitter exocytosis has implicated synaptobrevin in this process. To further the study of synaptic function in a genetically tractable organism and to generate a tool to disable neuronal communication for behavioural studies, we have expressed a gene encoding tetanus toxin light chain in Drosophila. Toxin expression in embryonic neurons removes detectable synaptobrevin and eliminates evoked, but not spontaneous, synaptic vesicle release. No other developmental or morphological defects are detected. Correspondingly, only synaptobrevin (n-syb), but not the ubiquitously expressed syb protein, is cleaved by tetanus toxin in vitro. Targeted expression of toxin can produce specific behavioral defects; in one case, the olfactory escape response is reduced.

Amino Acid Sequence↗
PubMed1993

Characterization and acute phase modulation of canine apolipoprotein H (beta 2-glycoprotein I).

Apolipoprotein H (ApoH) is a 50 kDa glycoprotein capable of binding to negatively charged phospholipids and is a probable inhibitor of the blood coagulation pathway, platelet aggregation, and platelet prothrombinase activity, as well as being involved in autoimmune disease. We have cloned and sequenced a full length ApoH cDNA clone from a beagle dog liver library. Its derived amino acid sequence shows high cross-species similarity to ApoH from other mammals. Canine ApoH mRNA expression is down regulated during an experimentally induced inflammatory response establishing that it is a negative acute phase reactant.

Acute-Phase Proteins↗
PubMed1993

alpha 1-Proteinase inhibitor, elastase activity, and lung disease severity in cystic fibrosis.

The potential role of neutrophil elastase in exacerbating pulmonary infection and tissue damage in cystic fibrosis (CF) has led to proposals for treatment of lung disease in CF with the elastase inhibitor, alpha 1-proteinase inhibitor (alpha 1PI). Reports that alpha 1PI is inactivated in the CF lung suggest that the effectiveness of alpha 1PI therapy depends on the quantity of elastase present and the extent of alpha 1PI inactivation, both of which are expected to vary with disease severity. In this study we assessed the elastase-alpha 1PI profile in sputum and plasma from CF patients with various degrees of pulmonary involvement. Levels of active elastase in sputum samples increased with severity of pulmonary disease (F ratio = 5.63, p < 0.01), as did sputum levels of alpha 1PI (F ratio = 4.88, p < 0.01). A positive correlation was observed between sputum levels of active elastase and alpha 1PI (r = 0.68, p < 0.005). Plasma alpha 1PI levels were also elevated in CF patients compared with control subjects (p < 0.005), indicating a compensatory increase in plasma and sputum levels of alpha 1PI in response to increased elastase load. Molar levels of total immunogenic neutrophil elastase were, on average, 12 times higher than alpha 1PI in CF sputum. These results suggest that the major contributor to the elevated levels of active elastase observed in the CF lung is an increase in elastase release rather than inactivation of alpha 1PI.

Adolescent↗
PubMed1984

Projections from C2 and C3 nerves supplying muscles and skin of the cat neck: a study using transganglionic transport of horseradish peroxidase.

Transganglionic transport of HRP has been used to trace the pathways and termination sites of cutaneous and muscle afferent axons entering from the C2 and C3 dorsal rami. The muscle afferent projection in the spinal cord is restricted and (apart from the ventral horn) largely confined to the intermediate gray matter. There is a muscle afferent projection to the ventrolateral main cuneate nucleus and a complex pattern of projection through the extent of the external cuneate nucleus. In contrast, the cutaneous spinal projection is abundant with extensive filling of axons in the tract of Lissauer and many termination sites in the lateral substantia gelatinosa. Axons enter the lateral gray matter of the cervical spinal cord from the dorsal columns and the dorsolateral funiculus and terminate in the lateral one-third of the dorsal horn as far rostral as the spinomedullary junction. Axons of the tract of Lissauer form a complex web around the dorsal horn and many penetrate rostrally to the region of the spinomedullary junction, where they terminate among clusters of interstitial cells on and close to the dorsal medullary surface. Cutaneous afferent axons from the dorsal columns turn into the main cuneate nucleus and enter a dense mass of HRP-reaction product which occupies the most ventrolateral part of the nucleus for its entire length.

Animals↗
PubMed1984

Contralateral, midline, and commissural motoneurons of neck muscles: a retrograde HRP study in the cat.

Retrograde transport of HRP has been used to examine the distribution of motoneurons supplying the dorsal neck muscles biventer cervicis, and complexus in the cat. Retrogradely filled cells were present in the expected sites in lamina IX of the ventral horn, but were not confined to that area. Retrogradely labelled cells were also found more dorsally in the ventral horn and in the white matter medial to the ventral horn. Other filled cells were found in the commissural nuclei and in laminae VII and VIII contralateral to the nerve being dipped. Cells in the ipsilateral lamina IX ranged in size from 15 to 70 microns. Cells lying outside this region were smaller with the majority having mean equivalent diameters, of 40 microns or less.

Animals↗
PubMed1980

Bronchial carcinoid metastatic to skin. Light and electron microscopic findings.

This case report illustrates the value of ultrastructural examination of an undifferentiated carcinoma mestastatic to skin. In this patient, ultrastructural study of a cutaneous nodule demonstrated cytoplasmic neurosecretory granules characteristic of an amino precursor-uptake and decarboxylation cells (APUD) tumor and supported the diagnosis of metastatic bronchial carcinoid. Additional nine cases of bronchial carcinoids metastatic to skin are also briefly reviewed.

Bronchial Neoplasms↗
PubMed1976

[A new therapeutic principle in hepatic coma: parenteral supply of neutral amino acids].

The effect of two different amino acid solutions given i.v. was investigated in dogs with hepatic encephalopathy after portacaval shunt. The results suggest that (a) isocaloric protein-free nutrition has no impact on the characteristic plasma amino-gram, (b) the infusion of modified concentrations of 6 neutral amino acids may reduce mortality and morbidity in dogs with hepatic coma, and (c) manipulation and normalization of plasma amino acids may be efficacious in providing adequate nutrition while minimizing hepatic encephalopathy.

Amino Acids↗
PubMed1975

Myelopathy simulating spinal cord tumor.

Three cases of demyelinating or necrotizing myelopathy are presented in which gradual onset of symptoms, slowly progressive course and widened cord shadow on myelography led to the erroneous diagnosis of intramedullary spinal cord neoplasm. Two of the cases also had inconclusive surgical explorations. We would suggest that patients who seem to have even a typical clinical and myelographic picutre of an intrinsic cord neoplasm have a period of further observation before radiotherapy is begun and that a vigorous search be made for evidence of disseminated disease.

Adult↗