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Biomedical subjects

N Canal

Publications and source records attributed to N Canal.

At least 109 records · Page 6Linked to original sources
PubMed1985

Characterization of the gamma-aminobutyric acid receptor system in human brain gliomas.

The properties of [3H]-gamma-aminobutyric acid [( 3H]GABA) binding were studied in biopsied specimens from normal human brain and from 18 cases of human brain gliomas, made up of 6 astrocytomas, 6 glioblastomas, 3 oligodendrogliomas, and 3 medulloblastomas. In fresh membranes obtained from normal gray and white matter one population of Na+-dependent GABA receptors was observed, while in the frozen Triton X-100-treated membranes two distinct populations of Na+-independent binding sites were detected. Specific GABA binding sites in brain gliomas were shown only in frozen Triton X-100-treated membranes. As in normal tissue, these receptors are Na+-independent and bind [3H]GABA with two distinct affinity components. The biochemical profiles of [3H]GABA binding to membranes obtained from different tumors of glial origin are quite similar and cannot be related to the degree of malignancy of the neoplasia.

Brain Neoplasms↗
PubMed1984

Richards-Rundle syndrome, cochleovestibular dysfunction and neurofibromatosis in a family.

The Richards-Rundle syndrome (RRS) is characterized by hearing loss, mental deterioration, ataxia, primary hypogonadism and autosomal recessive transmission. In a sibship of six members we found two sisters with RRS together with baldness, impaired GH and PRL secretion after stimulation and different degrees of impaired insulin secretion. Cochleovestibular investigation of the sibship revealed in each subject more or less severe forms of bulbo-pontine cochleovestibular dysfunction. Three members of the same sibship had cutaneous signs of abortive forms of neurofibromatosis: the son of one of these subjects had a severe form of fully developed neurofibromatosis. Whether there is a pathogenetic linkage between the hereditary multisystemic degeneration (RRS), the dysembryopathy (neurofibromatosis) and the cochleovestibular dysfunction in this family is still not clear.

Acoustic Impedance Tests↗
PubMed1984

Study of some lysosomal glycohydrolases in tumors of the nervous system.

The specific activities of five glycohydrolases of lysosomal origin (beta-N-acetylglucosaminidase, beta-glucuronidase, beta-galactosidase, alpha-mannosidase and alpha-fucosidase) were measured in different types of primary and metastatic tumors of the human nervous system. The activities of these hydrolytic enzymes in samples of tumor tissue were compared with those in the white matter of 'control' tissue. The specific activities of beta-glucuronidase and beta-N-acetylglucosaminidase were significantly higher (P less than 0.001) in each group of tumors than in normal cerebral matter. The activities of the other hydrolases were sometimes significantly increased in primary tumors, but not always. In metastatic tumors, they were also significantly higher (P less than 0.01).

Acetylglucosaminidase↗
PubMed1983

Multiple forms of protein kinase from normal human brain and glioblastoma.

The biochemical characteristics of the protein kinase (PK; adenosine triphosphate-protein phosphotransferase, EC 2.7.1.37) isozymes in subcellular preparations from normal human brain cortex and glioblastoma were investigated after chromatography on diethylaminoethyl cellulose, and the following results have been obtained. Two major isozyme forms, eluted by 50 and 200 mM phosphate buffer, are present in both cytosol and membrane-derived preparations from cerebral cortex. Furthermore, these isozyme forms have properties similar to those referred to as type I and type II cyclic adenosine 3':5'-monophosphate-dependent PK. In these chromatographic isozymes, cyclic adenosine 3';5'-monophosphate is more active in stimulating the basal PK enzyme than is cyclic guanosine 3':5'-monophosphate. In glioblastoma, the PK activity from cytosol and particulate preparations is resolved by diethylaminoethyl cellulose in four peaks. In cytosol, the major portion of the enzyme is eluted with a 300 mM buffer (about 50% of the total basal PK activity) and is cyclic nucleotide dependent. On the contrary, in glioblastoma particulate, the PK enzyme is mainly eluted at 50 and 100 mM buffer; neither of these isozymes is cyclic nucleotide dependent. As for cytosol, only the particulate isozyme eluted at 300 mM buffer is strongly activated by cyclic nucleotides. Finally, in both glioblastoma subcellular preparations, only a type II cyclic adenosine 3':5'-monophosphate-dependent PK is present.

Brain↗
PubMed1983

Metabolic and morphologic changes induced by serotonin in skeletal muscle of rats after abdominal aorta ligation.

Myopatic changes observed in muscle of rats after abdominal aorta ligation and/or serotonin injection have been regarded as a suitable model to explore the possibility that vasoactive treatments induce muscular damage similar to human myopathies. In the present study, we investigated the effect of serotonin administration to normal and aorta-ligated rats on cAMP-dependent protein-kinase (PK) and hydrolytic enzymes in skeletal muscle.

Animals↗
PubMed1979

Cyclic nucleotide phosphodiesterase activity in muscle of patients with carcinoma.

Cyclic nucleotide phosphodiesterase activity has been measured in muscle biopsies taken from healthy controls and from cancer patients. In both groups the muscles were clinically and morphologically normal. The phosphodiesterase activity was significantly increased in muscles from cancer patients using both cyclic AMP and cyclic GMP as substrate. These findings are in line with previous reports indicating that malignancy may interfere with metabolism of the host muscular tissues, and suggest the possibility that the observed biochemical changes might be an aspect of an early muscle neurogenic involvement.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1978

Guanylate cyclase activity in normal and diseased human muscle.

Guanylate cyclase activity has been studied in muscle of normal subjects and of patients suffering from muscular and neuromuscular diseases. In normal tissue a guanylate cyclase activity was found in both soluble and particulate fractions of homogenate. We found also that the kinetic analysis of the enzyme of soluble differed from that of particulate fraction. A decrease of guanylate cyclase activity in crude homogenate was observed in muscular dystrophies, in neuromuscular atrophies, and in inflammatory forms of muscle disease.

Cyclic GMP↗
PubMed1975

The metabolism of cyclic-3'-5'-adenosine monophosphate (cAMP) in diseased muscle.

Adenyl cyclase (AC) and cyclic nucleotide phosphodiesterase (PDE) have been studied in muscle from patients affected with muscular and neuromuscular diseases as well as in muscle of rats after experimental denervation. A diminution of AC was observed in Duchenne's dystrophy, in neurogenic atrophies, in inflammatory forms, in myasthenia and myotonia. PDE was diminished in Duchenne's dystrophy and increased in all other diseases considered. Both enzymes were increased in rat muscle after nerve transection. The possible mechanism underlying the biochemical alterations observed are discussed including unmasking of extra-activity due to changed metabolic environment, tissue destruction and activation of lysosomal activity.

Adenylyl Cyclases↗