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Biomedical subjects

A Grasso

Publications and source records attributed to A Grasso.

At least 127 records · Page 7Linked to original sources
PubMed1980

Black widow spider toxin-induced calcium fluxes and transmitter release in a neurosecretory cell line.

Several polypeptide neurotoxins affect presynaptic functions by interfering with chemical neurotransmission. This group of toxins includes botulinum toxin, tetanus toxin, beta-bungaro-toxin and black widow spider toxin (BWSTx). While the effect of the first three toxins is mainly a rapid and severe block of neurotransmitter release, BWSTx affects transmission by a massive stimulation of mediator release. Despite various hypotheses put forward to explain the action of BWSTx at the level of nerve terminals, there is still a considerable degree of uncertainty as to the cation dependence of venom action. Study of the toxin mode of action at the biochamical level has been hampered by the complexity and cellular heterogeneity of the preparations used, neuromuscular junction or synaptosomes. PC12 cell line, derived from a rat phaeochromocytoma, seems to be an excellent model in view of its property of synthesising and storing noradrenaline, dopamine and acetylcholine, and releasing them in depolarising conditions. We have recently shown that highly purified BWSTx stimulates secretion from PC12 cells of previously taken up radioactive dopamine (DA) and noradrenaline (NA) (ref. 14 and manuscript in preparation). We report here that the earliest detectable event after toxin treatment of such cells is a massive increase of cytosolic calcium.

Animals↗
PubMed1980

Familial centronuclear myopathy.

A girl with typical clinical and histologic features of centronuclear myopathy (CNM) is described. The electromyogram was clearly of myopathic type; the motor conduction velocity was reduced. The analysis of the pedigree, in which three other members were similarly affected, suggests autosomal dominant inheritance with low penetrance.

Blepharoptosis↗
PubMed1980

[Neurological and muscular manifestations of thalassemia major (author's transl)].

Five out of 89 sicilian children with homozygous thalassemia major had central nervous system signs but they were probably not due to the disease. Much more commonly peripheral nerve or muscle involvement was detected. Among 51 patients who had detailed clinical and electrophysiological studies (EMG and nerve conduction studies) 20 (39.2%) had clinical signs of neuro-muscular disease and five others had electrophysiological abnormalities only. Serum CPK was normal in all cases. The results suggest that muscle disease in thalassemia major is mostly of neurogenic origin.

Adolescent↗
PubMed1978

14-3-2 protein in rat brain.

The distribution of the 14-3-2 protein in rat brain was investigated by immuno-electron microscopy using antiserum to the protein conjugated with peroxidase. 14-3-2 was demonstrated in the nuclear membrane, the endoplasmic reticular membranes and in the plasma membrane of nerve cells. The protein was also localized to the presynaptic densities and to the pre- and postsynaptic membranes. It could not be demonstrated in the membranes of the Golgi complex, inner membrane of mitochondria or in the nucleoplasm of neurons. No 14-3-2 protein was found in astrocytes, oligodendrocytes or in non-neuroectodermal tissue elements.

Animals↗
PubMed1978

Schwartz-Jampel syndrome in two daughters of first cousins.

The clinical and pathological features of two sisters born from consanguineous parents and affected by the rare Schwartz-Jampel syndrome are reported. The parental consanguinity of these two patients and the findings of electromyographic changes in the mother strongly support an autosomal recessive pattern of inheritance. No response of growth hormone secretion to arginine and insulin stimulation tests was found.

Abnormalities, Multiple↗
PubMed1977

14-3-2 protein in rat brain synapses.

The distribution of the 14-3-2 protein in rat brain synapses was studied by immuno electron microscopy. The protein was localized to the postsynaptic web and to the postsynaptic membrane, but was also prominent both in the presynaptic membrane and in the presynaptic densities. No significant activity was observed in the synaptic vesicles.

Animals↗
PubMed1977

Preparation and properties of the brain specific protein 14-3-2.

A brain specific protein, 14-3-2, has been isolated from bovine brain by the use of ammonium sulfate precipitation, gel filtration on Sephadex G-150, and ion exchange chromatography on DEAE-cellulose and DEAE-Sephadex. It is an acidic protein, in agreement with the high content of glutamic and aspartic acid, that is composed of a single polypeptide chain of mol. wt. 50,000. Immunochemical tests using antiserum to purified 14-3-2 showed that the protein is present in at least 100-fold greater amounts in brain than in any other rat tissue. Furthermore, 14-3-2 was found in brains of a number of vertebrate species, although the antigen is apparently not entirely identical in all species tested. The protein 14-3-2 can be considered to be a species non-specific protein which is neuronal in origin.

Amino Acid Sequence↗
PubMed1977

The subunit structure of bovine brain 14-3-2.

Two aspects of the subunit structure of the bovine brain specific protein 14-3-2 have been examined. On the one hand, native 14-3-2 has been separated into two fractions by hydroxylapatite chromatography. One eluted at the same position when chromatographed on the same column, while the other redistributed into the same two fractions again. Amino acid analysis of these two forms of 14-3-2 gave results that were not significantly different under the condition of analysis. Furthermore, when each peak was subjected to cyanogen bromide cleavage, very similar elution profiles of the resultant fragments were obtained. The two pools also cross-reacted with antiserum to 14-3-2. Reaction of purified 14-3-2 with dimethylsuberimidate caused the formation of covalently bound protein units of 100,000 molecular weight when measured by sodium dodecyl sulfate polyacrylamide gel electrophoresis, as opposed to the 50,000 minimal molecular weight normally detected. On the other hand, analysis of the soluble tryptic peptides of S-[14C]carboxymethyl 14-3-2 yielded only three distinct radioactive peptides, each with one residue of S-carboxymethylcysteine whereas 8 are expected on the basis of the amino acid composition of the 50,000 molecular weight polypeptide chains. Thermolysin digestion of a similarly modified 14-3-2 preparation yielded all of the radioactivity in 5 S-carboxymethylcysteine-containing peptides. The partial amino acid sequence of these peptides indicates that they represent 4 unique areas of the polypeptide chain. Since 8 such peptides were expected, that is, double the number found, the minimum structural unit of the protein must be of 25,000 molecular weight. The results of these experiments do not permit distinction between a duplication of the structure within a single polypeptide chain or the alternate possibility of two polypeptide chains bound by unusually strong non-covalent bonds. These results suggest that 14-3-2 is a covalently linked dimer of 25,000 mol.wt. units that can aggregate to form larger species of 100,000 mol.wt. and higher.

Amino Acid Sequence↗