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Biomedical subjects

M A Grillo

Publications and source records attributed to M A Grillo.

At least 55 records · Page 3Linked to original sources
PubMed1983

Ornithine decarboxylation in rat liver nuclei.

1. Decarboxylation of ornithine in rat liver cytosol produces putrescine; on the contrary, no putrescine is formed in nuclei. 2. In nuclei, decarboxylation is not inhibited by alpha-difluoromethylornithine and depends on NADH reoxidation. This shows that decarboxylation occurs after transamination of ornithine. 3. The increase of ornithine transaminase activity may be partially responsible for the enhanced decarboxylation after 1-methyl-3-isobutylxanthine administration. Data obtained in the presence of Ca2+ suggest that modification of nuclear Ca2+ concentration may also be responsible.

1-Methyl-3-isobutylxanthine↗
PubMed1983

Neutral red stains ganglia in the vagal motor pathway to ferret trachea without affecting ganglionic transmission.

To determine the effect of Neutral red (0.01%) on neural transmission through ganglia, we used an in vitro nerve-muscle preparation of ferret trachea. Before, during, and after incubating the trachea in Neutral red, we induced isometric muscle contractions first by activating preganglionic fibers with electrical stimulation of the vagus nerve, and then by activating postganglionic nerve fibers with electrical field stimulation. Incubation in Neutral red (0.01%) for 45 min at 38 degrees C reduced the responses to both pre- and postganglionic activation. When the control responses to pre- and postganglionic activation were matched. Neutral red depressed the 2 responses to the same degree, implying that the depression was confined to postganglionic structures. Washout of Neutral red from the medium restored the responses to both pre- and postganglionic activation. Histologic examination of all tissues proved that the ganglia were still stained after the washout procedure. We conclude that Neutral red (0.01%) depresses smooth muscle contractions evoked through neural pathways, and that this depression is reversible and confined to postganglionic structures, leaving ganglionic transmission intact.

Animals↗
PubMed1980

Induction of an ornithine decarboxylase-antizyme by diaminopropane in chicken kidney and intestinal mucosa.

Administration of diaminopropane to chickens, injected with insulin in order to induce ornithine decarboxylase, prevents the increase of the decarboxylase activity in kidney and in the intestinal mucosa, not in the heart, In the first two tissues, not in the last one, an ornithine decarboxylase-antizyme is detected. The ornithine decarboxylase-antizyme appears therefore to be involved in vivo in the regulation of ornithine decarboxylase activity.

Animals↗
PubMed1970

Cytoplasmic inclusions resembling nucleoli in sympathetic neurons of adult rats.

A distinctive cytoplasmic inclusion consisting of a convoluted network of electron-opaque strands embedded in a less dense matrix was identified in the neurons, but not in the supporting cells, of rat sympathetic ganglia. This ball-like structure, designated "nematosome," measures approximately 0.9 micro and lacks a limiting membrane. Its strands (diameter = 400-600 A) appear to be made of an entanglement of tightly packed filaments and particles approximately 25-50 A thick. Cytochemical studies carried out with the light microscope suggest the presence of nonhistone proteins and some RNA. Usually only one such structure is present in a cell, and it appears to occur in most ganglion cells. Although they can be seen anywhere in the cell body, nematosomes are typically located in the perinuclear cytoplasm, where they are often associated with smooth-surfaced and coated vesicles. In fine structure and stainability, they bear a resemblance to the fibrous component of the nucleolus. Subsynaptic formations, which are a special feature of some of the synapses in sympathetic ganglia, appear similar to the threadlike elements in the nematosomes. The possibility that these three structures-nucleolus, nematosome, and subsynaptic formation-may be interrelated in origin and function is discussed.

Animals↗