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Biomedical subjects

G Monaco

Publications and source records attributed to G Monaco.

At least 73 records · Page 4Linked to original sources
PubMed1984

Microsurgical approach to pancreatic duct occlusion in the pig by means of a prolamine solution.

Prolamine is an alcoholic solution of zein, with the property of polymerizing within 15 minutes in a humid medium. Such a substance has been injected in the pancreatic duct of 10 pigs with a microsurgical technique, causing complete occlusion. The prolamine gel produces a progressive fibrosclerosis of the exocrine pancreatic parenchyma, sparing the endocrine portion. The resulting pancreatic atrophy avoids the occurrence of inflammatory complications that often hamper surgery on such gland. The 10 pigs under study showed post-operative normal values of blood glucose and insulin, and a decrease in serum alpha-amylase levels. Complications occurred in only one case, and the microscopic pattern was similar in all cases. Microsurgical approach and use of prolamine are considered effective both in pancreatic transplantation and in chronic pancreatitis.

Animals↗
PubMed1983

The cytoskeleton of hydatid cyst cultured cells and its sensitivity to inhibitors.

Cell cultures obtained from the germinal layer of hydatid cysts of the parasitic tapeworm Echinococcus granulosus were characterized with respect to their microtubule and microfilament systems. These were stained using monospecific antibodies against tubulin from sea urchin spermatozoa or sheep brain and against Dictyostelium discoideum actin as well as rhodamine conjugated phalloidin. The results show that the distribution of microtubules nad actin containing fibres of these cells is remarkably similar to that of mammalian cells both during interphase and mitosis. Hydatid cells, however, could not be stained with a specific antivimentin antibody. Indirect immunofluorescence with antitubulin antibodies of inhibitor treated cells shows that hydatid cell microtubules are sensitive to several antimicrotubular drugs including benzimidazole derivatives, colchicine, vinblastine, and griseofulvin.

Actins↗
PubMed1983

Immunoregulatory T subsets in chronic active viral hepatitis: characterization by monoclonal antibodies.

Immunoregulatory T subsets, defined by monoclonal antibodies, were enumerated in children affected by HBsAg-positive chronic active hepatitis. The helper to suppressor/cytotoxic cells ratio was lower in patients than in age-matched controls. The lower ratio was mainly due to an increase of lymphocytes of the suppressor/cytotoxic phenotype. Helper cells were even fewer in severe chronic hepatitis patients, thereby lowering still further the helper/suppressor ratio. Therapy seemed to influence the ratio in patients affected by moderate active chronic hepatitis, for four of eight children treated with azathioprine and prednisone had a ratio within -1 SD of normal values. The increase of the suppressor/cytotoxic cells in patients affected by chronic hepatitis might be a means for limiting virus-induced cell hyperactivity.

Adolescent↗
PubMed1982

Observations on the molecular components stabilizing the microtubular system of the marginal band in the newt erythrocyte.

Microtubules have been classified as either stable or labile, according to their resistance towards depolymerizing agents. The highest stability belongs to those organized in composite structures, in which many other proteins are associated with the tubulin. Among these microtubular systems, the marginal band of amphibian erythrocytes is unusually stable. This system can be readily isolated from Triturus red blood cells, and therefore lends itself very readily to ultrastructural and biochemical analyses. Immunofluorescence and electrophoretic analyses of the isolated bands reveal 14 components, among which tubulin, actin, myosin and a 90K glycoprotein were identified. Tannic acid-glutaraldehyde fixation reveals a conspicuous opaque material surrounding the microtubules. Cationized ferritin binding suggests the presence of anionic sites. Moreover, neuraminidase causes the disorganization of the microtubule-associated opaque material. The 90K glycoprotein is presumed to be related to the unusual stability of the microtubular system forming the marginal band.

Actins↗
PubMed1978

Nerve growth factor potentiates actomyosin adenosinetriphosphatase.

The nerve growth factor protein (NGF) favors polymerization of brain actin and induces its organization to form paracrystalline structures that activate myosin ATPase (ATP phosphohydrolase, EC 3.6.1.3) to an extent greater than actin alone. Binding studies show that the initial 1:1 stoichiometry of NGF-G-actin complexes decreases to 1:7-10 when polymerization is ended and paracrystalline structures are formed. The ratio becomes even lower when heavy meromyosin is added in the absence of ATP, suggesting that heavy meromyosin displaces NGF bound to actin microfilaments. This conclusion is supported by the finding that when heavy meromyosin is added to NGF-microfilament complexes, under conditions for "decorating" microfilaments, the usual paracrystalline structure of the complexes disappears. The NGF-mediated organization of actin and activation of myosin ATPase is visualized as a self-regulatory and self-propagating mechanism, because progressive displacement of the growth factor induced by heavy meromyosin binding to F actin as ATP consumption proceeds renders an increasingly higher amount of NGF free for new interactions. These findings are discussed in the light of the mechanism of action of NGF in the target cells.

Actins↗
PubMed1977

Effect of NGF on in vitro preformed microtubules. Evidence for a protective action against vinblastine.

The nerve growth factor protein (NGF) induces organization of in vitro preformed microtubules (MTs) to form multiple arrays. These complexes, in cross-section, appear to be formed by clusters of single tubules in parallel in close contact with center distance similar to the diameter of a microtubule. In the absence of NGF, on the contrary, microtubules are far apart from each other. Addition of vinblastine to NGF-MT complexes does not result in the usual reorganization of microtubules into paracrystalline arrays, noticeable when the growth factor is not present. The vinblastine treated NGF-MT complexes have several round-shaped elements along the tubules and at their endings which, at higher magnification, appear to be formed by closely packed, ring-like structures. These 'boutons' are postulated to represent the point of resistance to the depolymerizing action of the vinca alkaloid. These findings are discussed in relation to a similar antagonistic effect observed in vivo between NGF and vinblastine and to the possible involvement of microtubules in the mechanism of action of the growth factor.

Animals↗
PubMed1977

[Prevention of arrhythmias during heart catheterization].

The utility of using beta blocking drugs, specifically Pindolol, as a prophylaxis for arrhythmia during cardiac microcatheterism according to Grandjean's technique has been observed. The drug is even more useful when it is considered that it does not affect dp/dt value.

Arrhythmias, Cardiac↗
PubMed1975

Thyroglobulin biosynthesis in "cold" and "hot" nodules in the human thyroid gland.

Studies on "cold" and "hot" nodules from human thyroid gland have been carried out to investigate thyroglobulin biosynthesis and to correlate carbohydrates incorporation and thyroid hormone formation in thyroglobulin. The aim of the investigation was to ascertain the role of carbohydrates of the protein molecule in its migration to the iodinating site of the cell. Thyroid slices from two cases with "cold" and two with "hot" nodules were incubated for 30 to 120 min with [3H]leucine, [3H]carbohydrates (ManNAc, Gal, Man, GlcNAc, GalNAc) and 125I. Soluble and particulate iodoproteins, solubilized by digitonin, were identified by density gradient centrifugation and immunoprecipitation; following hydrolysis carbohydrates and iodothyronines were identified by paper chromatography and chemically determined. While the rate of leucine incorporation into TG increased with time in both "cold" and "hot" nodules, the "cold" nodule, with respect to the "hot" tissue, showed: much lower efficiency incorporating carbohydrates and iodine into TG; lower thyroid/medium ratio of radioiodine; less total soluble protein and soluble TG; more particulate protein and solubilized TG; 1/3 of the carbohydrate and iodine chemical content; only minute amounts of labeled iodothyronines in TG compared to normal levels in "hot" tissue. The formation of thyroid hormone, in enzymatically iodinated TG, and the iodinating activity of the 105,000 X g pellet, incubated with low iodine TG, were similar in both "cold" and "hot" tissues. These results demonstrate that the "cold" nodule is able to synthesize thyroglobulin but the protein is defective in its carbohydrate content. The deficient iodine transport into "cold" tissue and impaired hormonal synthesis are confirmed. The incomplete incorporation of carbohydrates into thyroglobulin in the "cold" nodule could be important for the maturation and migration of the molecule to the iodinating site of the cell

Acetylgalactosamine↗