Papers by Angelo Borghetti
Biochemistry, 1972
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Biochemical Society Transactions, 1980
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Biochemical Journal, 1976
Insulin regulation of amino acid transport across the cell membrane was studied in a variety of m... more Insulin regulation of amino acid transport across the cell membrane was studied in a variety of mesenchymal cell directly isolated from avian and mammalian tissues or collected from confluent cultures. Transport activity of the principal systems of mediation in the presence and absence of insulin was evaluated by measuring the uptake of representative amino acids under conditions approaching initial entry rates. Insulin enhanced the transport rate of substrate amino acids from the A system(α-aminoisobutyric acid, L-proline, glycine, L-alanine and L-serine) in fibroblasts and osteoblasts from chick-embryo tissues, in mesenchymal cells (fibroblasts and smooth muscle cells) from immature rat uterus, in thymic lymphocytes from young rats and in chick-embryo fibroblasts from confluent secondary cultures. In these tissues, the uptake of amino acid substrates of transport systems L and Ly+ (L-leucine, L-phenylalanine, L-lysine) was not affected by the presence of the hormone. No insulin co...
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Biochemical Society Transactions, 1985
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European Journal of Cancer and Clinical Oncology, 1987
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Cancer research, 1982
Rate of proliferation and amino acid transport were assessed in simian virus 40 (SV40)-transforme... more Rate of proliferation and amino acid transport were assessed in simian virus 40 (SV40)-transformed 3T3 cells by measurements of growth rate quotient and L-serine uptake via System ASC, respectively. Growth rate and cell density of the cultures were varied by modifying: (a) the number of cells initially plated; and (b) the period spent by the cells in culture. The growth rate quotient of SV40 3T3 cells was not correlated with cell density. Sparse cultures exhibited marked fluctuations in their growth rate as a function of time, whereas, under comparable conditions, crowded cultures retained some form of growth control by density. Transport activity by System ASC decreased as a function of increased cell density following a complex trend described by a double-exponential equation. The density-dependent decrease in amino acid transport was not accompanied by a parallel change in the rate of cell proliferation. These results indicate that alterations in amino acid transport are not link...
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Journal of acquired immune deficiency syndromes, 1992
During HIV infection of CEM cells cultured in vitro, significant differences in growth rate and p... more During HIV infection of CEM cells cultured in vitro, significant differences in growth rate and protein turnover were observed with different viral preparations. There was a significant inhibition of proliferation after infection with crude HIV supernatants. On the other hand, infection with purified HIV particles obtained by filtration, differential centrifugation, and isopycnic sedimentation led to a progressively increasing stimulation of cell growth. This early stimulation was prevented by neutralizing the virus with soluble CD4 molecules. Study of cell growth in the presence of a purified membrane preparation indicated that membrane fragments contaminating the crude HIV supernatant were responsible for the observed growth inhibition. Interestingly, the stimulation of proliferation was also observed with heat-inactivated virus or after inhibition of viral replication with ZDV. In the presence of purified HIV virions, the rate of general protein synthesis was not inhibited, as is...
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The Journal of Physiology, 2002
Porcine pulmonary arterial endothelial cells accumulated myo‐inositol and taurine, as well as bet... more Porcine pulmonary arterial endothelial cells accumulated myo‐inositol and taurine, as well as betaine, during adaptation to hypertonic stress. The cells grew and maintained their normal morphology during culture in hypertonic (0.5 osmol (kg H2O)−1) medium that contained osmolytes such as betaine, myo‐inositol or taurine at concentrations close to reported physiological values. The cells did not grow well in hypertonic medium depleted of potential compatible osmolytes. After a few days, cell density decreased by about 50 % and many cells rounded up and detached from the plates, their nuclei showing clear apoptotic morphology. The caspase‐3 activity of the cells also increased dramatically under these conditions, but remained negligibly low when betaine and myo‐inositol were added to the medium. Addition of betaine and myo‐inositol to hypertonic medium depleted of compatible osmolytes increased the number of colonies remaining after 12 days of culture; with each solute at 30–100 μmol ...
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Radiation Research, 2006
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The Journal of General Physiology, 2004
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Journal of Cellular Physiology, 1995
The simultaneous exposure of WI‐38 human fibroblasts (HF) to a heat shock (45°C, 30 min) and an a... more The simultaneous exposure of WI‐38 human fibroblasts (HF) to a heat shock (45°C, 30 min) and an alkaline shift (≥ pH 8.0) in the incubation medium increased and extended the expression of heat shock proteins (hsps). Hsp70 was the most prominent inducible hsp synthesized during the recovery phase after the double shock, and the increase in synthesis depended on the degree of alkalinization during the heat shock. The accumulation of inducible hsp70, which was shown by Western blotting to occur in the late part of the recovery period, was more pronounced in the cells exposed to alkaline medium during the heat shock. Northern blotting did not reveal any increase in hsp70 mRNA, although time course studies following the double shock indicated a more prolonged presence of mRNA. Hsp70 gene activation was evaluated by a gel retardation assay using a 32P‐labelled DNA oligonucleotide containing the heat shock consensus element (HSE) and a heat shock‐induced specific binding protein (heat shoc...
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Journal of Cellular Physiology, 1977
When chicken serum was added to serum‐deprived quiescent cultures of chick embryo fibroblasts the... more When chicken serum was added to serum‐deprived quiescent cultures of chick embryo fibroblasts the activity of amino acid transport by means of the A system, as measured by α‐aminoisobutyric acid and L‐proline uptake after discrimination of the contribution of interacting systems, increased with time of exposure to serum between 30 and 120 minutes (remaining constantly high thereafter). Under the same conditions, DNA synthesis, as measured by thymidine incorporation, increased abruptly six to eight hours after the addition of serum. Serum‐mediated increases of transport activity by the A system have also been detected with glycine, L‐alanine and L‐serine. Transport activities of systems ASC, L and Ly+ did not change appreciably (or decreased slightly) after the addition of serum. The stimulation of amino acid transport was apparently proportional to the length of exposure to serum; its rate declined progressively with time after withdrawal of serum from the culture medium. Kinetic an...
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Journal of Cellular Physiology, 1984
The transport of selected neutral amino acids known as good substrates of amino acid transport Sy... more The transport of selected neutral amino acids known as good substrates of amino acid transport System L has been studied in chick embryo fibroblasts exposed for 4 hours to hyperosmolar culture medium. The activity of the L system, as measured by initial rates of L-phenylalanine uptake, increased in hyperosmolarity treated cells when determined before any cell depletion of intracellular amino acids. This effect was lost after depletion but reappeared after reloading the cells with pertinent substrates of System L. This transport activity appeared to be related to the internal level of amino acids capable of exchange through System L. In hyperosmolarity-treated chick embryo fibroblasts a higher level of System L substrates was obtained during the reloading phase in comparison to control cells. This expanded amino acid pool reflected an increased activity of transport System A, an agency of amino acid mediation known to enlarge its capacity following a hyperosmolar treatment of chick embryo fibroblasts (see Tramacere et al., 1984). L-Methionine, a preferred substrate of both A and L systems, appeared to be involved in the coupling between the activity of amino acid transport Systems A and L in these cells.
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Journal of Cellular Physiology, 1980
The transport of selected neutral and cationic amino acids has been studied in Balb/c 3T3, SV3T3,... more The transport of selected neutral and cationic amino acids has been studied in Balb/c 3T3, SV3T3, and SV3T3 revertant cell lines. After properly timed preincubations to control the size of internal amino acid pools, the activity of systems A, ASC, L, and Ly+ has been discriminated by measurements of amino acid uptake (initial entry rate) in the presence and absence of sodium and of transportspecific model substrates. L‐Proline, 2‐aminoisobutyric acid, and glycine were primarily taken up by system A; L‐alanine and L‐serine by system ASC; L‐phenylalanine by system L; and L‐lysine by system Ly+ in SV3T3 cells. L‐Proline and L‐serine were also preferential substrates of systems A and ASC, respectively, in 3T3 and SV3T3 revertant cells. Transport activity of the Na+‐dependent systems A and ASC decreased markedly with the increase of cell density, whereas the activity of the Na+‐independent systems L and Ly+remained substantially unchanged. The density‐dependent change in activity of syst...
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Journal of Cellular Biochemistry, 1986
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Experimental Cell Research, 1986
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Experimental Cell Research, 1991
... and Transformed SV3T3 Cells1 LUCIA SiLVOTTI,* PIER GIORGIO PETRONINI,* ALBERTO MAZZINI,t GlUS... more ... and Transformed SV3T3 Cells1 LUCIA SiLVOTTI,* PIER GIORGIO PETRONINI,* ALBERTO MAZZINI,t GlUSEPPE PlEDIMONTE,* AND ANGELO F. BORGHETTI ... concanava lin Aselected Balb c SV3T3 revertant cells (RevSV3T3 cells) were kindly provided by Dr. Paul H. Black ...
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Experimental Cell Research, 1984
The effect of exposure of chick embryo cells to increasing concentrations of Na+ in the culture m... more The effect of exposure of chick embryo cells to increasing concentrations of Na+ in the culture medium on the subsequent amino acid transport as determined at physiological osmolarity was investigated in detail. It was found that the hyperosmolar treatment stimulated amino acid transport in a dose-dependent manner up to 200 mM Na+. Changes were measurable as early as 1 h after altering Na+ and reached a maximum after 4 h, remaining constant thereafter. The maintenance of this effect required continuous exposure of the cell to high Na+ in the culture medium. Hyperosmolarity-mediated increases in amino acid transport activity by system A have been detected with L-proline and L-alanine. Transport activities of systems ASC and L did not change appreciably after exposure of the cells to high Na+. Inhibition of protein synthesis by cycloheximide or RNA synthesis by actinomycin D (actD) prevented these uptake changes. Kinetic analysis indicated that the stimulation of the activity of transport system A by high Na+ treatment occurred through a mechanism affecting Vmax rather than Km.
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Cancer Letters, 1988
A tyrosine protein kinase activity has been detected in the mitochondrial fraction purified from ... more A tyrosine protein kinase activity has been detected in the mitochondrial fraction purified from normal and virus-transformed cultured cells. The addition of serum to cells whose growth was restricted by serum limitation induced a marked decrease of tyrosine kinase activity associated with the mitochondrial fraction. At all the culture conditions tested this enzyme activity always resulted several fold higher in the virus-transformed cells than in the normal parental cells.
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Papers by Angelo Borghetti