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Biomedical subjects

G Salvatore

Publications and source records attributed to G Salvatore.

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

Effects of a purified diet enriched with animal protein on female rats. Preliminary report.

On account of many epidemiological data showing a definite correlation between mortality from heart disease and animal protein content in the diet, the effect of a 60 days purified diet enriched with casein and lactalbumin has been studied in rats. Although the experimental time was rather short, histological study of the organs has shown morphological alterations of liver, adrenal glands, heart, gastrocnemius muscle and kidney. Determination of some haematic parameters have revealed that from 15th day of diet glucose and triglycerides begin to increase moderately but significantly while azotemia is definitely high only after the 60th day. No changes vice versa were observed of cholesterol, creatinine and electrolytes level.

Adrenal Glands↗
PubMed1984

Carcinoma of the breast with osteoclast-like giant cells. Fine-needle aspiration cytology, histology and electron microscopy of 5 cases.

Five cases of a rare peculiar type of mammary carcinoma with osteoclast-like stromal giant cells are reported. The tumors are characterized by a large number of multinucleated giant cells in intimate association with the epithelial neoplastic cells. The light and electron microscopic observations confirm the earlier reports about the origin of the giant cells from mononuclear histiocytes as a local response to some tumoral products. In 3 patients a preoperative fine-needle aspiration biopsy was carried out and the cytomorphology of these tumors is described to alert cytopathologists who encounter this entity in the routine breast mass aspiration biopsy.

Adult↗
PubMed1983

Comparative study of the arterial and lacunary systems of the ventricular myocardium of elasmobranch and teleost fishes.

The typical fish heart has a spongy trabeculated ventricular myocardium (spongiosa) supplied by the venous blood of the intertrabecular spaces (lacunae); hence it is called a "venous heart." However, in some fishes a more complex ventricular muscle is found (mixed type), in which the spongiosa is covered by an outer layer of densely arranged myocardial bundles (compacta). The compacta receives oxygenated blood from the coronary vessels. The objective of this study was to investigate relations between myoarchitecture and blood supply with an emphasis on the hitherto unexplored, putative vascular connections between the arterial and the lacunary circuits. Using histological methods combined with vascular cast techniques and India ink injections, it was possible to define four different types of ventricular myocardium and its microvasculature. In some of them an intramural network arises from the subepicardial arterial system supplying the compacta and also is distributed to the spongiosa. Extensive arterio-luminal vessels connect this coronary bed with the lacunary circuit of the spongiosa, so realizing the first evolutionary step of the Thebesian system. The highest development of these connections is found in some very active pelagic fishes. The functional morphology of these vascular patterns is discussed in relation to the phylogenetic and functional context of the fish heart. It appears that the concept of the piscine heart as a typical "venous" type is an oversimplified generalization, at least on morphological grounds.

Animals↗
PubMed1982

A new mechanism for the reabsorption of thyroid iodoproteins: selective fluid pinocytosis.

Rat thyroid hemilobes were incubated in presence of exogeneous, heterologous and homologous thyroglobulins. The median density of the thyroglobulin molecules originally added to the medium was compared with that of the molecules remaining at the end of a three-hour incubation period (37 degrees C). A certain degree of specificity in the reabsorption process of thyroglobulin was found: the uptake of homologous molecules (rat) was higher than heterologous (hog) molecules. The median density of the iodoproteins remaining after the incubation did not change for the heterologous whereas it shifted towards lower density for the homologous thyroglobulins (equilibrium labelled, 35 iodine atoms/molecule). In addition, rat follicular cells display selectivity in the endocytosis of homologous thyroglobulin. Among the rat molecules, the normally iodinated are taken up more actively than the lowly iodinated or newly synthesized ones. Dissimilarity in the median density of the thyroglobulin molecules before and after endocytosis was only evident for the equilibrium-labelled, normally iodinated rat preparation: the disappearance from the medium of 25-30% of exogenous iodoproteins was sufficient to lower significantly the median density of the remaining molecules. This means that the thyroglobulin molecules having higher density are taken up preferentially by the tissue. A mechanism involving specific interactions between the iodoproteins and the surface of thyroid cell is suggested.

Animals↗
PubMed1981

Thyroglobulin interactions with thyroid membranes. Relationship between receptor recognition of N-acetylglucosamine residues and the iodine content of thyroglobulin preparations.

Bovine thyroglobulin has been subjected to sequential glycohydrolase treatment in order to define further the components of the carbohydrate chain which are important in binding of the glycoprotein to bovine thyroid membranes. Preparations of asialoagalactothyroglobulin exhibit the best binding, suggesting that exposed N-acetylglucosamine residues on the B carbohydrate chain of thyroglobulin play an important role in the interaction of thyroglobulin with the thyroid membranes. Enhanced binding of asialoagalactothyroglobulin to microsomal, lysosomal, and Golgi membranes, as well as to thyroid cells in culture, was also observed. Isopycnic rubidium chloride gradient centrifugation, a procedure used in the isolation of thyroglobulin molecules with a low iodine content, also isolates thyroglobulin molecules with a low sialic acid content and with an increased ability to interact with wheat germ agglutinin, a lectin which recognizes exposed N-acetylglucosamine residues. The studies further indicate that there is a correlation between iodine content, exposed N-acetylglucosamine residues, and the binding of thyroglobulin to thyroid membranes.

Acetylglucosamine↗
PubMed1979

Thyroglobulin interactions with thyroid plasma membranes. The existence of specific receptors and their potential role.

Thyroglobulin binds to isolated thyroid plasma membrane preparations. Binding is pH- and temperature-dependent with 10-fold better binding at pH 5.0 and 37 degrees C than at 0 degrees C and pH 6.0 through pH 7.5. Binding is, however, maximal in 90 min at all pH values and temperatures examined. Although salts can inhibit or enhance thyroglobulin binding depending on the temperature or pH, conditions approaching those of the physiological state are not inhibitory; physiological conditions do inhibit thyrotropin binding to the same membrane preparations. 125I-Labeled thyroglobulin binding is poorly reversed by unlabeled thyroglobulin at all pH values and temperatures studied; excess unlabeled thyroglobulin can, however, readily prevent binding. At pH values greater than 6.0 and at 0 degrees C, the iodine content of thyroglobulin can affect binding, and the 27 S thyroid iodoprotein is relatively ineffective in preventing the binding of the 19 S species. At pH 5.0 and 37 degrees C, there is no difference in binding of highly and less iodinated thyroglobulin, and the 27 S thyroglobulin iodoprotein is effective in preventing 19 S thyroglobulin binding. The complex nature of these results is interpreted in the light of additional data which show (i) that the thyroid membrane recognizes asialothyroglobulin and (ii) that at pH 5.0 and 37 degrees C a membrane-associated neuraminidase is activated which removes sialic acid from thyroglobulin. Vibrio cholerae neuraminidase can substitute for the endogenous neuraminidase. The receptor on thyroid membranes for asialothyroglobulin is similar to the asialoglycoprotein receptor on liver membranes (Morell, A.G., Gregoriadis, G., Scheinberg, I.H., Hickman, J., and Ashwell, G. (1971) J. Biol. Chem. 246, 1461-1467) in that sialic acid on the receptor is critical for receptor expression. It is distinct from the liver asialoglycoprotein receptor in its binding specificity and in its sensitivity to different bacterial and mammalian neuraminidase preparations. Relationships between thyroglobulin and thyrotropin receptors on thyroid membranes are explored, and the functional role of the thyroglobulin receptor is discussed.

Animals↗
PubMed1976

Isopycnic centrifugation of thyroid iodoproteins: selectivity of endocytosis.

Isopycnic centrifugation in RbCl was shown to be an effective method both for evaluating the iodine content of thyroglobulin labelled in vivo and for the fractionation of thyroglobulin molecules as a function of their iodine content. Iodination and degradation of thyroid iodoproteins were studied by this method and by zonal centrifugation in sucrose density gradients. Based on these methods it was shown that iodination in vivo is a selective process, 19-S and poorly iodinated thyroglobulin having a higher reactivity toward iodine than 27-S and iodine-rich thyroglobulin. The disappearance of iodoproteins from the thyroid was evaluated by equilibrium, labelling the iodoproteins, blocking iodine incorporation with thiourea derivatives and observing (by sucrose gradient and by RbCl isopycnic centrifugation) at different times the properties of the remaining molecules. Among molecules of different size (19-S and 27-S) and among molecules of the same size (19 S) but different iodine content it was shown that reabsorption from the thyroid gland occurred at the same rate. It was concluded, therefore, that the degradative pathway is essentially a random, non-selective process. Newly iodinated (pulse-labelled) iodoproteins were degraded faster than preexisting molecules. Among the pool of those newly iodinated thyroid proteins, 27-S molecules were reabsorbed faster than 19-S molecules and iodine-rich thyroglobulin molecules were reabsorbed faster than the iodine-poor ones. Since iodination in vivo occurs as repeated pulses of iodine incorporation, it is suggested that this latter phenomenon is a regulatory mechanism which minimizes degradation of molecules which are iodine-poor and have a lower hormonal content.

Animals↗
PubMed1975

Relationship between iodination and the polypeptide chain composition of thyroglobulin.

Thyroglobulin was isolated from thyroid glands of normal guinea pigs and from animals treated with thiouracil. These preparations were fractionated by isopyknic centrifugation in RbCl into proteins of varying iodine content. When the disulfide bonds of these protein fractions were reduced and analyzed by polyacrylamide gel electrophoresis in Na dodecyl-SO4, t hree species were observed with molecular weights of 295,000 (A), 210,000 (B), and 110,000 (C). Species A comprised 80% of the protein in thyroglobulin of 0.04% iodine and 13% in thyroglobulin of 0.68% iodine content. Species C showed the opposite relationship, comprising 10% of the low and 70% of the high iodine thyroglobulin. Species B was relatively independent of the iodine content and represented approximately 20% of the protein. Iodine analysis of these proteins showed species A to be lowest and species C highest. It appears that the subunit composition of thyroglobulin depends on the degree of iodination and that species A should be the only one present in the absence of iodination.

Animals↗
PubMed1975

The site of sialic acid incorporation into thyroglobulin in the thyroid gland.

Iodine incorporation into thyroglobulin is known to occur within the lumen of the thyroid follicle. Since incorporation of sialic acid, which occupies a terminal position in the oligosaccharide chains, is also a later event in thyroglobulin synthesis, the possibility that sialic acid might be incorporated after thyroglobulin secretion was investigated. In one experimental approach normal rat thyroid hemilobes were incubated with radioactive precursors. Thyroglobulin, analyzed by equilibrium centrifugation in RbCl, had a median density which varied according to the moiety labeled in the following increasing order: leucine smaller than galactose smaller than sialic acid smaller than iodine. The molecules having the highest density were labeled only with iodine. In the second approach, thyroid hemilobes were taken from rats treated with cycloheximide for 16 hours to stop protein synthesis and allow nascent molecules to be secreted, and incorporation of precursors into thyroglobulin was analyzed by sucrose gradient centrifugation. Leucine incorporation was 6% of control but the amino acid was found in the NH2-terminal position. N-Acetylmannosamine (sialic acid precursor) and galactose incorporation were also completely inhibited whereas iodine incorporation was 10% of control. Incorporation was not restored by thyrotropin treatment, and the sialyltransferase and iodination systems were reduced only to 50 to 70% of control. The results indicate that sialic acid is incorporated only in nascent thyroglobulin and not in thyroglobulin molecules already secreted into the follicular lumen. A large fraction of the iodine incorporation also seems to occur in newly synthesized thyroglobulin.

Animals↗