Search PubMed⌕ Search

Biomedical subjects

J Guy

Publications and source records attributed to J Guy.

At least 127 records · Page 7Linked to original sources
PubMed1983

Primary position vertical nystagmus and cerebellar ataxia.

Hereditary cerebellar ataxia was evaluated clinically and by electro-oculography in three members of a family. There was no clinical evidence of exttra-cerebellar dysfunction although quantitative eye movement analysis did shown internuclear ophthalmoparesis and slow saccadic velocity suggestive of brainstem dysfunction. In addition, oculomotor examination showed primary position vertical nystagmus in all patients. Other findings were in accord with previous reports of cerebellar-related oculomotor dysfunction.

Adolescent↗
PubMed1982

Further studies on the identification of neurons containing immunoreactive alpha-melanocyte-stimulating hormone (alpha-MSH) in the rat brain.

In order to identify more accurately the organelles containing immunoreactive alpha-melanocyte-stimulating hormone (alpha-MSH) in the rat brain, attempts were made to improve the ultrastructural preservation of the neural tissue used for immunostaining of the peptide. With the post-embedding staining technique, the quality of the preservation was not adequate since only low concentrations (0.2-0.5%) of OsO4 could be used for postfixation. Higher concentrations of OsO4 completely destroyed the antigenicity of alpha-MSH. With the pre-embedding technique in which the immunostaining is performed prior to postfixation with OsO4, a good preservation could be obtained making possible the identification of organelles and classification of endings containing immunoreactive alpha-MSH. In the dendrites, the staining was rather diffuse without any clear association with organelles. In the endings, the staining was mostly restricted to dense core vesicles with some degree of diffusion in the cytoplasm. None of the positive endings were seen making synaptic contact. These results support the hypothesis that alpha-MSH could be released in sites other than the classical synaptic junction and act as a local hormone.

Animals↗
PubMed1981

Differential projections of two immunoreactive alpha-melanocyte stimulating hormone (alpha-MSH) neuronal systems in the rat brain.

Immunocytochemical localization of alpha-MSH was performed in the brain of rats of which the arcuate nucleus has been destroyed by treatment with monosodium glutamate in the neonatal period. In these animals, alpha-MSH cell bodies normally found in the arcuate nucleus were almost completely absent. The reactive fibers found in the ACTH-beta-LPH pathway were also markedly decreased. On the other hand, alpha-MSH cell bodies located in the dorsolateral hypothalamus as well as fibers located outside the ACTH-beta-LPH pathway were not decreased. These results strongly suggest that alpha-MSH cell bodies in dorsolateral hypothalamus have projections completely different from those located in the arcuate nucleus.

Animals↗
PubMed1981

Effects of chronic demyelination on axonal transport in experimental allergic optic neuritis.

Axonal transport studies were undertaken to determine the effect of chronic demyelination on axonal function in experimental allergic optic neuritis in the guinea pig, an animal model for multiple sclerosis. Fast and slow components of axonal transport over the prelaminar, laminar, and retrolaminar portions of the optic nerve head and at the foci of demyelination in the retrobulbar optic nerve were evaluated by the autoradiographic grain-counting technique. At 6 hr there was a significant increase in grain counts over the demyelinated foci and in the regions proximal to the demyelination, including the swollen disc. At day 1 there was no significant difference in the grain counts at the site of demyelination when compared to the myelinated portion of the nerve. However, at days 3 and 7 there was a decrease in the number of grains over the demyelinated areas. These results indicate impairment of axonal function in chronic demyelination. Moreover, in this pathologic process, most of the synthesized materials appear to move in the fast transport phase, unlike in the normal optic nerve where the bulk of materials move by slow transport.

Animals↗
PubMed1981

Pulmonary core biopsy by percutaneous needle aspiration.

Percutaneous aspiration needle biopsy for pulmonary lesions has been practised for many years but has not until recently gained popularity. Further proof of its simplicity, safety and accuracy for both central and peripheral lesions is given in this retrospective study of 181 biopsies performed in a community hospital. The diagnostic yield was higher in neoplastic (87.5%) than in nonneoplastic (68.4%) lesions and higher in malignant (91%) than in benign (58.3%) neoplasms. The larger the lesion the higher was the success rate--95.6% if the lesion was larger than 3 cm. The complication rate was low (14.9%) and there were no deaths. There was no difference in the success rate or the incidence of complications between biopsy done for central or peripheral lesions. The complication rate did not differ between large and small lesions, localized or diffuse. The sample could be used for cell block histologic sectioning, which gave the same diagnostic accuracy as cytologic examination. There were no false-positive cytologic diagnoses. During the procedure the operator (a radiologist in all cases) was able to predict the diagnosis in cases of hamartoma and neurofibroma.

Adult↗
PubMed1980

Identification of a second category of alpha-melanocyte-stimulating hormone (alpha-MSH) neurons in the rat hypothalamus.

An immunocytochemical localization of alpha-melanocyte-stimulating hormone (alpha-MSH) as well as ACTH and a fragment (16K) of the common precursor of ACTH and beta-lipotropin (beta-LPH) was performed in rat brain. Two different groups of neuronal cell bodies showing alpha-MSH-like immunoreactivity (alpha-MSH-LI) were observed in the hypothalamus. One group of neurons located in the arcuate nucleus was shown to contain not only alpha-MSH-LI, but also ACTH and the 16K fragment. A second category of alpha-MSH-LI-containing neurons was characterized by the complete absence of staining for ACTH and 16K fragment. These neurons were mainly located in the dorsal-lateral portion of the hypothalamus. Immunoelectron microscopy showed that immunostaining for alpha-MSH was restricted to dense core vesicles in the positive perikarya. Nerve fibers staining for alpha-MSH (but not for ACTH and 16K fragment) were also observed outside the ACTH-beta-LPH pathway, especially in the cortex, caudate-putamen nucleus and hippocampus. These findings strongly suggest the presence of two different neuronal systems reacting with antibodies to alpha-MSH.

Adrenocorticotropic Hormone↗
PubMed1980

Localization of a 16,000-dalton fragment of the common precursor of adrenocorticotropin and beta-lipotropin in the rat and human pituitary gland.

To clearly identify cells and organelles containing the common precursor (31,000 dalton) for both adrenocorticotropin (ACTH) and beta-lipotropin (beta-LPH), an immunohistochemical localization of a fragment (16,000 dalton) of the precursor that is not common to beta-LPH and ACTH was conducted in rat and human pituitary glands. With the help of specific antibodies that do not cross-react with beta-LPH and ACTH, the 16,000-dalton fragment was localized in the cells that also produce ACTH and beta-LPH in both the pars distalis and pars intermedia of the rat pituitary. At the electron microscope level, the secretory granules that contain ACTH were also stained for 16,000-dalton fragment. In the human pituitary, the 16,000-dalton fragment was also observed in all the secretory granules of lipocorticotrophs. These results suggest that, after enzymatic cleavage, fragment(s) of the common precursor and/or the whole common precursor remain packaged within the secretory granules with peptides of known activity.

Adrenocorticotropic Hormone↗
PubMed1980

Immunohistochemical localization of gamma-endorphin in the rat pituitary gland and hypothalamus.

To gain more information about cells and organelles involved in the secretion of gamma-endorphin in the rat pituitary gland, an immunohistochemical localization of this peptide was conducted at both light and electron microscopic levels. Using an antiserum to gamma-endorphin which shows little cross-reactivity with beta-lipotropin (beta-LPH) and beta-endorphin, it has been demonstrated that gamm-endorphin is present in all cells of the intermediate lobe and the corticotropic cells of the anterior lobe. At the electron microscopic level, staining for gamma-endorphin was restricted to the secretory granules which also contain ACTH and beta-LPH, suggesting that all of these peptides are released concomitantly during exocytosis. In the hypothalamus, immunostaining possibly related to both gamma- and beta-endorphin but not to beta-LPH was also observed in nerve fibers and not in cell bodies.

Animals↗