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Biomedical subjects

N Miani

Publications and source records attributed to N Miani.

At least 19 recordsLinked to original sources
PubMed1983

[Effect of proteins S100 on RNA and protein biosynthesis in neurons and glial cells of the rat brain].

The effects of brain-specific proteins S100 injected into lateral ventricles of rat brain on biosyntheses of RNA, proteins and endogenous proteins S100 in neurons and glial cells were investigated. It was found that exogenous proteins S100 essentially and irreversibly stimulate RNA and total protein syntheses in glial cells, while bovine serum albumin stimulates RNA and protein syntheses in neurons but not in glial cells. The dynamics of changes in the content of newly synthesized endogenous proteins S100 in glial cells and neurons are suggestive of transport of S100 protein molecules synthesized by glial cells, into the neurons. The absence of appreciable changes in the indicated parameters in rats injected with total rabbit sera proteins as well as in animals subjected to "false injections" provide evidence for the specificity of metabolic effects of proteins S100 and serum albumin.

Animals↗
PubMed1981

[Endotoxins in the plasma and ascitic fluid of the cirrhotic patient. Their clinical significance].

The endotoxin presence was tested by Limulus Lysate Test (LLT) in plasma and ascites of 29 patients with cirrhosis, all having demonstrable portal hypertension and ascite. It was positive in plasma in 7 cases (24.1%) and in ascite in 12 cases (73.12%). All the cases with endotoxin in the plasma were positive in ascite too. 21 patients presented porto-sistemic encephalopathy from 1 to 4 grade, 1 case only had the clinical features of hepatorenal syndrome. The CHE and protrombin test values were significantly different in LLT positive patients in plasma and ascite respect to the values of negative ones.

Ascitic Fluid↗
PubMed1981

Membrane proteins in human skin tumors.

The microsomal, mitochondrial, and nuclear fractions of cutaneous tumors have been investigated. Cutaneous tumors were homogenized and microsomal, mitochondrial, and nuclear fractions were purified. The membrane proteins were solubilized with sodium duodecyl sulfate (SDS). The membrane lipids were removed and membrane proteins were solubilized again in a small volume of SDS solution and chromatographed in SDS-acrylamide slab-gel. The plates were stained with Coomassie Brilliant Blue to show protein bands. The preliminary results show that the electrophoretic profiles of microsomal proteins are characteristic of some tumors.

Carcinoma↗
PubMed1980

Immunocytochemical localization of the brain-specific S-100 protein in the pituitary gland of adult rat.

The brain-specific S-100 protein was localized at the electron microscopic level in the anterior and posterior pituitary gland of adult rat by indirect immunoperoxidase histology. The protein was found in the stellate cells of the pars distalis and tuberalis, in the marginal cells that line the hypophyseal cleft and in the glia-like cells, the pituicytes, of the neural lobe. The pituicytes, the stellate cells and the marginal cells have in common at least two properties: they all express a brain-specific marker and they are satellite cells to the secretory axons in the neural lobe and of the secretory cells in the adenohypophysis. These properties suggest that the S-100 cells in the pituitary gland are neuroectodermal in origin, possibly glial in nature.

Animals↗
PubMed1979

Appearance of new alpha-bungarotoxin-acetylcholine receptors in cultured sympathetic ganglia of chick embryos.

alpha-Bungarotoxin (alpha-BuTX) has been used as a marker for studying the production of alpha-bungarotoxin-acetylcholine receptors (alpha-BuTX-AChRs) in explants of chick embryo sympathetic ganglia cultured in vitro. New alpha-BuTX-AChRs appear rapidly in the explants after blocking of the pre-existent ones with the toxin (40% of the total receptors at 3 h). There is a portion of alpha-BuTX-AChRs in the explants which for a short time is not accessible to the toxin. This portion constitutes the precursor pool of receptors and represents 18% of the total. The precursor pool of receptors supplies the neurons with new receptors for 1-2 h in the absence of protein synthesis. The appearance of new receptors from the precursor pool is an energy-dependent process.

Acetylcholine↗
PubMed1978

alpha-Bungarotoxin-acetylcholine receptors in the chick ciliary ganglion: effects of deafferentation and axotomy.

alpha-Bungarotoxin (alpha-BuTX) binds in a saturable and practically irreversible fashion to membrane-associated receptors in the ciliary ganglion of the adult chick. The binding of toxin to receptors is competitively inhibited by nicotinic cholinergic ligands, and for these properties the receptors are regarded as acetylcholine receptors of the nicotinic type (alpha-buTX-AChRs). The rate constant of association (K1) and dissociation (K-1) of the toxin-receptor reaction has been estimated to be K1 = 7.4 x 104 M(-1) sec(-1) and K-1 = 9.6 X 10(-6) sec(-1), respectively. Light autoradiography shows that most, if not all, the receptors are related to surface membrane, probably to synaptic areas of both choroid and ciliary neurons. The choroid neurons contain more receptors than the ciliary ones. A single chick ciliary ganglion binds specifically 47 fmole of alpha-BuTX in situ corresponding to 2.83 x 1010 alpha-BuTX-AChRs/ganglion. No changes in number and distribution of the toxin receptors occur following preganglionic denervation. Conversely, postganglionic axotomy causes a rapid disappearance of the receptors in situ. Since binding experiments in vitro revealed a partial, instead of a total, loss of the receptors, it is suggested that the disappearance of the receptors in situ includes both a partial loss of the original receptors and the masking of the residual ones.

Acetylcholine↗
PubMed1975

Soluble and membrane-bound S-100 protein in cerebral cortex synaptosomes. Properties of the S-100 receptor.

Within cerebral cortex synaptosomes, S-100 protein can be recovered in two forms: soluble and membrane-bound. Synaptosomal S-100 is mainly a soluble protein (85 percent). The membrane-bound S-100 is differently distributed in the synaptosomal membranes, intraterminal mitochondria, and synaptic vesicles. S-100 binds to a specific receptor. The binding is time-dependent, reversible and saturable with respect to S-100. The number of receptors is calculated to be about 9 times 10(12)/mg protein, since saturation is achieved at 31 ng [125I]S-100/0.1 mg protein of disrupted synaptosomes. The rate constant for association of S-100 with its receptor at 37 degrees C, k1, is 4.74 times 10(4) M(-1) sec(-1), and the rate constant for dissociation, k-1, 9.24 times 10(-4) sec(-1).

Animals↗
PubMed1975

Concanavalin A as a probe for studying the mechanism of metabolic stimulation of leukocytes.

The disruption of the molecular organization of the plasma membrane of leukocytes by phagocytosable particles, or by agents such as surfactants, antibodies, phospholipase C, fatty acids and chemotactic factors, leads to a stimulation of the phagocyte oxidative metabolism. Concanavalin A (Con A) has been used as a tool to study the mechanism of this metabolic regulation. The binding of Con A to the surface of polymorphonuclear leukocytes (PMNL) or macrophages produces a rapid enhancement of oxygen uptake and glucose oxidation through the hexose monophosphate pathway (HMP). This is explained by an activation of the granular NADPH oxidase, the key enzyme in the metabolic stimulation. The effect of Con A is not due to endocytosed lectin, since Con A covalently coupled to large sepharose beads still acts as stimulant. The metabolic changes caused by Con A are reversible. If, after the onset of stimulation, sugars with high affinity for Con A are added to the leukocyte suspension, the activity of granular NADPH oxidase and the rate of respiration and glucose oxidation return to their resting values. The metabolic burst, while partially supressed by treatment of PMNL with iodoacetate, sodium flouride and cytochalasin B, is slightly increased by colchicine. Con A induces a selective release of granular enzymes (beta-glucuronidase, peroxidase, alkaline phosphatase) from PMNL, whereas no leakage of cytoplasmic enzymes is observed. The enzyme release is inhibited by iodoacetate and by drugs known to increase cell levels of cyclic AMP. Based on a current view of the mode of interaction between Con A and cell surfaces, a model of the metabolic disruption of leukocytes is presented.

Animals↗