Terrence J Piva - Academia.edu (original) (raw)

Papers by Terrence J Piva

Journal of Cellular Biochemistry, 1998

The oxidative metabolism of glutamine in HeLa cells was investigated using intact cells and isola... more The oxidative metabolism of glutamine in HeLa cells was investigated using intact cells and isolated mitochondria. The concentrations of the cytoplasmic amino acids were found to be aspartate, 8.0 mM; glutamate, 22.2 mM; glutamine, 11.3 mM; glycine, 9.8 mM; taurine, 2.3 mM; and alanine, < 1 mM. Incubation of the cells with [14C]glutamine gave steady-state recoveries of 14C-label (estimated as exogenous glutamine) in the glutamine, glutamate, and aspartate pools, of 103%, 80%, and 25%, respectively, indicating that glutamine synthetase activity was absent and that a significant proportion of glutamate oxidation proceeded through aspartate aminotransferase. No label was detected in the alanine pool, suggesting that alanine aminotransferase activity was low in these cells. The clearance rate of [14C]glutamine through the cellular compartment was 65 nmol/min per mg protein. There was a 28 s delay after [14C]glutamine was added to the cell before 14C-label was incorporated into the cytoplasm, while the formation of glutamate commenced 10 s later. Aspartate was the major metabolite formed when the mitochondria were incubated in a medium containing either glutamine, glutamate, or glutamate plus malate. The transaminase inhibitor AOA inhibited both aspartate efflux from the mitochondria and respiration. The addition of 2-oxoglutarate failed to relieve glutamate plus malate respiration, indicating that 2-oxoglutarate is part of a well-coupled truncated cycle, of which aspartate aminotransferase has been shown to be a component [Parlo and Coleman (1984): J Biol Chem 259:9997-10003]. This was confirmed by the observation that, although it inhibited respiration, AOA did not affect the efflux of citrate from the mitochondria. Thus citrate does not appear to be a cycle component and is directly transported to the medium. Therefore, it was concluded that the truncated TCA cycle in HeLa cells is the result of both a low rate of citrate synthesis and an active citrate transporter. DNP (10 microM) induced a state III-like respiration only in the presence of succinate, which supports the evidence that NAD-linked dehydrogenases were not coupled to respiration, and suggests that these mitochondria may have a defect in complex I of the electron transport chain. Arising from the present results with HeLa cells and results extant in the literature, it has been proposed that a major regulating mechanism for the flux of glutamate carbon in tumour cells is the competitive inhibition exerted by 2-oxoglutarate on aspartate and alanine aminotransferases. This has been discussed and applied to the data.

Educational Media International, Jan 1, 2004

RMIT is a major Australian university of technology based in central Melbourne with regional and ... more RMIT is a major Australian university of technology based in central Melbourne with regional and international reach. It has made both online education and programme quality two central planks in its teaching and learning strategy in recent years. This paper proposes making the connection between these two strategic directions by working within a framework of programme quality assurance to evaluate

The Journal of pharmacy and pharmacology, 2014

Transforming growth factor (TGF)-β regulates the function of vascular endothelial cells and may b... more Transforming growth factor (TGF)-β regulates the function of vascular endothelial cells and may be involved in endothelial dysfunction. The canonical TGF-β pathway involves TGF-β receptor-mediated carboxy-terminal phosphorylation of Smad2; however, TGF-β signalling also activates numerous serine/threonine kinases that phosphorylate Smad2 in its linker region. The expression of phosphorylated Smad linker proteins were determined following TGF-β stimulation in the absence and presence of different serine/threonine kinase inhibitors in vascular endothelial cells. Proteins were quantified by Western blotting using specific antibodies to individual phosphorylated Smad2 linker region residues. TGF-β mediated the phosphorylation of all four Smad2 linker region residues of interest. Erk and Jnk specifically phosphorylate Ser245 while all mitogen-activated protein kinases phosphorylate Ser250 and Ser255. Thr220 and Ser245 are phosphorylated by phosphoinositide 3 kinase (PI3K), while Ser255 w...

Journal of Experimental Marine Biology and Ecology, 2005

The deleterious effects of temperature-induced coral bleaching, a process by which corals lose th... more The deleterious effects of temperature-induced coral bleaching, a process by which corals lose their endosymbiotic algae (zooxanthellae; genus Symbiodinium) primarily at temperatures above mean yearly maximums, has not been well described for alcyonacean soft corals (Coelenterata, Octocorallia). The study of Symbiodinium cells lost from Sarcophyton ehrenbergi, Sinularia sp., and Xenia sp., which have not been compared in bleaching studies, indicate that the soft coral S. ehrenbergi released the greatest number of symbiont cells, however, it was less susceptible to heat stress surviving temperatures of 34 8C for N39 h. Sinularia sp. showed intermediate levels of bleaching tolerance to elevated temperatures, surviving prolonged exposures at 32 8C, but dying within 24 h at 34 8C. Xenia sp., however, was the most vulnerable to high heat stress maximally releasing Symbiodinium at temperatures V30 8C. This evidence indicates that Xenia sp. is even more susceptible to elevated temperatures than Acropora spp., previously reported to be the most vulnerable coral species to elevated temperature-induced bleaching.

Targeted oncology, 2015

Rituximab, the CD20-directed antibody, has become a standard component of treatment regimens for ... more Rituximab, the CD20-directed antibody, has become a standard component of treatment regimens for patients with B cell non-Hodgkin's lymphoma (NHL). The use of rituximab has resulted in greatly improved response and survival rates with less toxicity relative to standard chemotherapeutic regimes. However, relapse and recurrence is common, particularly in indolent varieties which remain incurable, requiring alternate therapeutic options. The subsequent coupling of β-emitting isotopes such as (131)I and (90)Y to anti-CD20 monoclonal antibodies (mAbs), including rituximab, has been steadily growing over the last decade and demonstrates even greater therapeutic efficacy with more durable responses. (177)Lutetium-labelled rituximab offers a number of convenient advantages over (131)I and (90)Y anti-CD20 mAbs for treatment of NHL, and a number of alpha-emitting isotopes lie at the frontier of consolidation therapy for residual, micrometastatic disease.

Molecular pharmacology, 2001

Histone deacetylase inhibitors show promise as chemotherapeutic agents and have been demonstrated... more Histone deacetylase inhibitors show promise as chemotherapeutic agents and have been demonstrated to block proliferation in a wide range of tumor cell lines. Much of this antiproliferative effect has been ascribed to the up-regulated expression of the cyclin-dependent kinase inhibitor p21(WAF1/CIP1). In this article, we report that p21 expression was up-regulated by relatively low doses of the histone deacetylase inhibitor azelaic bishydroxamic acid (ABHA) and correlated with a proliferative arrest. Higher doses of ABHA were cytotoxic. Cells that did not up-regulate p21 expression were hypersensitive to killing by ABHA and died via apoptosis, whereas up-regulation of p21 correlated with reduced sensitivity and a block in the apoptotic mechanism, and these cells seemed to die by necrosis. Using isogenic p21(+/+) and p21(-/-) cell lines and direct inhibition of caspase activity, we demonstrate that the reduced sensitivity to killing by ABHA is a consequence of inhibition of apoptosis ...

Mutation research, Jan 9, 1998

The surface of most cells includes a coterie of resident proteins which act as receptors for a wi... more The surface of most cells includes a coterie of resident proteins which act as receptors for a wide variety of ligands and other proteins which are potentially bioactive on cell-cell contact (juxtacrine effects), or else are released by enzyme activity to influence cell behaviour by autocrine or paracrine mechanisms. We previously found that UVC irradiation stimulates the release of TGFalpha from its membrane-bound preprocursor form whereby it acts as a stimulus to rapid, reparative cell multiplication; clearly this runs the risk hastening mitosis before UV-induced DNA damage is fully corrected, which in turn may increase the likelihood of residual lesions persisting and hence of new mutations being generated. We found that sublethal UVC irradiation (10 J m(-2)) of HeLa cell cultures also resulted in activation of ecto-aminopeptidase and ecto-endopeptidases which were maximal 16 and 20-24 h after irradiation, respectively. Both of these classes of protease were shown to be metallopr...

The Biochemical journal, 1997

GENBANK/dy examines the mechanisms of glucocorticoid-induced insulin resistance in rat soleus mus... more GENBANK/dy examines the mechanisms of glucocorticoid-induced insulin resistance in rat soleus muscle. Glucocorticoid excess was induced by administration of dexamethasone to rats for 5 days. Dexamethasone decreased the sensitivity of 3-O-methylglucose transport, 2-deoxyglucose phosphorylation, glycogen synthesis and glucose oxidation to insulin. The total content of GLUT4 glucose transporters was not decreased by dexamethasone; however, the increase in these transporters in the plasma membrane in response to insulin (100 m-units/litre) was lessened. In contrast, the sensitivity of lactate formation to insulin was normal. The content of 2-deoxyglucose in the dexamethasone-treated muscle was decreased at 100 m-units/litre insulin, while the contents of glucose 6-phosphate and fructose 2,6-bisphosphate were normal at all concentrations of insulin studied. The maximal activity of hexokinase in the soleus muscle was not affected by dexamethasone; however, inhibition of this enzyme by glu...

Advances in experimental medicine and biology, 1988

The Biochemical journal, 1992

1. The effects of insulin-like growth factor I (IGF-I) on the rates of glucose transport and util... more 1. The effects of insulin-like growth factor I (IGF-I) on the rates of glucose transport and utilization and its interaction with insulin were investigated in rat soleus muscle in vitro. IGF-I increased the rates of glucose transport, lactate formation, glycogen synthesis and the flux of glucose to hexose monophosphate, but it had no effect on the rate of glucose oxidation or glycogenolysis. 2. In the absence of insulin, low levels of IGF-I (0-30 ng/ml) increased the rate of glycolysis and the content of fructose 2,6-bisphosphate, but the content of glucose 6-phosphate remained unaltered; at higher levels of IGF-I (300-3000 ng/ml) the rate of glycolysis and the content of fructose 2,6-bisphosphate showed a further modest increase, but the content of glucose 6-phosphate doubled. Similar changes were seen when the level of insulin was increased from basal (0-0.4 ng/ml) to maximal (40 ng/ml). 3. Neither IGF-I nor insulin affected the contents of ATP, ADP, AMP, phosphocreatine or citrat...

Biochemistry international, 1992

The transport of glutamine was examined in bovine peripheral lymphocytes which had been cultured ... more The transport of glutamine was examined in bovine peripheral lymphocytes which had been cultured in the presence or absence of Concanavalin A (Con A). Glutamine transport was mediated by a triphasic transport system in both cell populations. The calculated kinetic parameters were: Km 1.0, 4.7 and 12.7 mM and Vmax 4.5, 6.0 and 9.0 nmol/min per mg protein respectively. Con A augmented the capacity rather than the affinity of the glutamine transport systems (Vmax rates being 8.0, 12.2 and 38.0 nmol/min per mg protein respectively). Transporter I displayed Michaelis-Menton kinetics, while transporters II and III were co-operative carriers possessing Hill coefficients of 2.3 and 9.5 respectively. Preliminary studies using amino acid and ion inhibition studies suggested that transporter I was a system ASC-type carrier, transporter III a system L carrier, while the nature of transporter II was unclear.

Clinical and experimental pharmacology & physiology, 2015

Peptidyl-prolyl cis/trans isomerases (PPIases) are a conserved group of enzymes that catalyse the... more Peptidyl-prolyl cis/trans isomerases (PPIases) are a conserved group of enzymes that catalyse the conversion between cis and trans conformations of proline imidic peptide bonds. These enzymes play critical roles in regulatory mechanisms of cellular function and pathophysiology of disease. There are three different classes of PPIases and increasing interest in the development of specific PPIase inhibitors. Cyclosporine A, FK506, rapamycin and juglone are known PPIase inhibitors. Herein, we review recent advances in elucidating the role and regulation of the PPIase family in vascular disease. We focus on peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (Pin1), an important member of the PPIase family that plays a role in cell cycle progression, gene expression, cell signalling and cell proliferation. In addition, Pin1 may be involved in atherosclerosis. The unique role of Pin1 as a molecular switch that impacts on multiple downstream pathways necessitates the evaluation of a hig...

ABSTRACT The effect of the fungal toxin gliotoxin on the adherence and viability of mouse L929 cu... more ABSTRACT The effect of the fungal toxin gliotoxin on the adherence and viability of mouse L929 cultured cells was examined. Gliotoxin at concentrations below 2 microM had no effect on cell function. The initial effect of exposure (6 h) resulted in the loss of cell adherence, with the non-adhered cells retaining viability. However, prolonged exposure (24 h) did not significantly enhance gliotoxin's effect on cell adherence, though the majority of non-adhered cells were found to have died by apoptosis, as confirmed from (i) electron microscopic examination and (ii) agarose gel electrophoresis of isolated DNA. The addition of foetal bovine serum to the culture medium had no effect on gliotoxin's activity. Ethanol (gliotoxin's solvent) had no effect on the assayed cell functions suggesting that the observed effects are due to gliotoxin alone. These results demonstrate for the first time that gliotoxin can cause apoptosis in cells of non-haematopoietic origins.

Cellular and Molecular Life Sciences, 2014

G protein-coupled receptor (GPCR) signalling is mediated through transactivationindependent signa... more G protein-coupled receptor (GPCR) signalling is mediated through transactivationindependent signalling pathways or the transactivation of protein tyrosine kinase receptors and the recently reported activation of the serine/threonine kinase receptors, most notably the transforming growth factor (TGF)-β receptor family. Since the original observation of GPCR transactivation of protein tyrosine kinase receptors, there has been considerable work on the mechanism of transactivation and several pathways are prominent. These pathways include the "triple membrane bypass" pathway and the generation of reactive oxygen species. The recent recognition of GPCR transactivation of serine/threonine kinase receptors enormously broadens the GPCR signalling paradigm. It may be predicted that the transactivation of serine/threonine kinase receptors would have mechanistic similarities with transactivation of tyrosine kinase pathways however, initial studies suggest that these two transactivation pathways are mechanistically distinct. Important questions are the relative importance of tyrosine and serine/threonine transactivation pathways, the contribution of transactivation to overall GPCR signalling, mechanisms of transactivation and the range of cell types in which this phenomenon occurs. The ultimate significance of transactivation dependent signalling remains to be defined but it appears to be prominent and if so will represent a new cell signalling frontier.