The Italian Journal of Biochemistry

V O L. 5 4, N. 3-4 SEPTEMBER-DECEMBER 2005


Why are polygenic hereditary diseases so difficult to investigate? An exercise of theoretical enzymology
Andrea Bellelli
Department of Biochemical "A. Rossi Fanelli", University of Rome La Sapienza, Rome, Italy

The Italian Journal of Biochemistry: 2005; 54(3-4): 229-231

Influence of age on Cu/Zn-Superoxide dismutase and indole 2,3-dioxygenase activities in rat tissues
Stefano Comai, Antonella Bertazzo, Eugenio Ragazzi, Laura Caparrotta, Carlo V.L. Costa, Graziella Allegri The Italian Journal of Biochemistry: 2005; 54(3-4): 232-239

Abstract. The aim of this study was to investigate in vitro the variations with age of the activities of the two antioxidant enzymes Cu/Zn-superoxide dismutase (SOD) and indole 2,3-dioxygenase (IDO) in metabolically active tissues of rats of various ages. In rats aged one week and 2-3 months the highest Cu/Zn-SOD activity was found in the liver and the lowest in the small intestine. At 12 and 18 months of age, the activity was higher in the brain and kidneys, when compared to the small intestine, lungs and liver. Cu/Zn-SOD activity decreased significantly after 2-3 months of age with advancing age in all tissues examined. In newborn rats IDO activity was present only in the small intestine. In the group of rats aged 2-3 months, the highest specific activity was observed in the small intestine and the lowest in the lungs and kidneys, whereas at 12 months of age, the highest IDO activity was found in the brain, with kidneys presenting the lowest activity. At 18 months, IDO returned to be more elevated in the small intestine. At 12 months of age the values of IDO in the tissues varied slightly, while at 18 months similar activities were found between the lungs and brain and between the small intestine and kidneys. In relation to age, IDO specific activity declined in the small intestine, after 2-3 months of age. In the lungs, the activity remained unchanged; in the brain and in the kidneys activity decreased significantly from 2-3 to 18 months of age. In conclusion, this study demonstrates an age-related decline in Cu/Zn-SOD and IDO activities, the two enzymes responsible for scavenging O2 •-.

Varying apparent rate constant: determination of uptake and release of protons during tetramer-dimer dissociation in human hemoglobin A
Jonathan O. Babalola, N. Adesola Babarinde, Titilola S. Akingbola
The Italian Journal of Biochemistry: 2005; 54(3-4): 240-247

Abstract. The effect of association-dissociation on the sulphydryl reactivity of human hemoglobin A is reported. The reactivity of CysF9(93)â towards the sulphydryl reagent, 5,5’-dithiobis(2-nitrobenzoate), is higher at lower concentrations of hemoglobin at all pH values. This is because hemoglobin dimers have higher sulphydryl reactivity than tetramers and it is known that the proportion of dimers increases as the hemoglobin concentration decreases. This study takes advantage of this observation to determine the tetramer-dimer dissociation constant, K4,2, of hemoglobin A and subsequently the proton uptake and the proton release during this process. The concentration dependence profiles of the apparent second-order rate constants, kapp, show that (between 2 and 20 µM heme) kapp decreases with increasing hemoglobin concentration. Above 30 M heme kapp remains fairly constant for all hemoglobin derivatives (oxy, carbonmonoxy and aquomethemoglobin) used. The pH dependence of the negative logarithm of tetramer-dimer dissociation constant, pK4,2, for oxy- (and for carbonmonoxy-) hemoglobin exhibits a biphasic character with a maximum near pH 7.4 (and 6.6). For aquomethemoglobin, pK4,2 decreases with increasing pH. The tetramer-dimer dissociation of human oxyhemoglobin A at an ionic strength of 200 mM uptakes 0.87Ý0.09 mole of protons between pH 6.2 to 7.4 phase and releases 0.84 0.09 mole of protons between pH 7.4 and 9.0 phase. Under a similar condition carbonmonoxyhemoglobin uptakes 0.54Ý0.05 mole of protons between pH 5.8 and 6.6 phase and releases 0.48Ý0.05 mole of protons between pH 6.6 and 9.0 phase. Aquomethemoglobin has only a single phase, it releases 0.39Ý0.05 mole of protons during tetramer-dimer dissociation.

Matrix metalloproteinases MMP-3 and MMP-1 levels in sera and synovial fluids in patients with rheumatoid arthritis and osteoarthritis
Randa K. Mahmoud, Amina K. El-Ansary, Hatem H. El-Eishi, Haba M. Kamal, Nehal H. El-Saeed
The Italian Journal of Biochemistry: 2005; 54(3-4): 248-257

Abstract. Objectives: To investigate whether serum levels of matrix metalloproteinases (MMP-3, stromelysin) and (MMP-1, collagenase) are specifically elevated in joint disease as rheumatoid arthritis (RA) compared to osteoarthritis (OA), and to assess how these markers reflect the clinical activity of RA compared to circulating cytokine as tumor necrosis factor-á (TNF-á) as well as established variables as [C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)]. Subjects and methods: This study included 22 patients with RA, 10 patients with OA and 10 healthy control subjects matched for age and sex. Patients with superimposed infection were excluded. Serum levels of MMP-3, MMP-1, TNF-á and CRP were assayed. Synovial fluid (SF) levels of MMP-3 and MMP-1 were also assayed. Results: Serum levels of TNF-á and CRP in RA patients were significantly higher than normal subjects. Serum MMP-1 was significantly elevated in patients with RA and OA, compared to healthy controls but there were no significant differences between patients with RA and those with OA. Serum MMP-3 levels did not differ between OA patients and normal sera. However, RA patients displayed significantly elevated levels of this enzyme, compared to OA and control sera. Levels of MMP-3 and MMP-1 in the SF of RA patients were significantly higher than in OA fluids. CRP, ESR, TNF-á and MMP-3 correlated significantly with the swollen joint count. The strongest positive correlations existed between rheumatoid activity as assessed by the levels of CRP and circulating levels of MMP-3. Similar correlations between TNF-á concentration and CRP, MMP-1 and MMP-3 were observed in RA patients. Serum levels of MMP-3 correlated significantly with serum concentrations of MMP-1 in RA patients (r=0.487,p< 0.05). There was close correlation between serum and SF concentrations of MMP-3 in RA patients (r=0.619, p<0.01). In the same patients there was highly significant correlation between SF concentrations of MMP-3 and MMP-1 (r=0.732, p< 0.001 ). Conclusions: Our data suggested that elevated MMP-3 levels reflected disease activity of RA better than cytokine levels. However, MMP-3 levels do not exceed the association of CRP with clinical activity.

During muscle ageing the activation of the mitogenic signalling is not sufficient to guarantee cellular duplication
Francesca Buricchi, Paola Chiarugi, Tania Fiaschi, Elisa Giannoni, Lucia Magnelli, Elena Fanti, Giovanni Raugei, Giampietro Ramponi
The Italian Journal of Biochemistry: 2005; 54(3-4): 258-267

Abstract. Satellite cells are quiescent cells that can be induced to proliferate by a variety of stimuli such as injury and exercise, providing in this way a source of new myoblasts that repopulate the damaged muscle. It is well known that, as senescence progresses, the muscle regenerative potential progressively diminishes, but the molecular mechanisms underlying this process are not yet completely defined. Many growth factors, including Platelet Derived Growth Factor (PDGF-BB)*, have been associated to satellite cells activation, acting as potent mitogenic agents for these cells. The aim of this study is to explore if the diminished response of senescent myoblasts to growth stimuli could be due to the inability to receive and transduce hormonal signals. Herein, we demonstrate that that although PDGF-r expression is down-regulated during senescence, the receptor is fully able to be phosphorylated and to transmit the signal. Although senescent myoblasts display increased level of phosphotyrosine phosphatases (PTPs), neither the PDGF receptor (PDGF-r) phosphorylation level nor the citosolic signal transduction machinery is affected. Indeed, we demonstrated that senescent human myoblasts are able to initiate a proper mitogenic signalling cascade, since the activation of mitogen-activated protein kinases (MAPK) and phosphatydil inositole 3 kinase (PI-3K) pathways is similar in young and senescent cells. Our data underline that, despite a conserved capability to activate PDGF-r after agonist stimulation and a functional signal transduction machinery, the mitogenic signal initiated by growth factors in senescent cells does not lead to cell division, being unable to overcome the cell cycle block, likely caused by the accumulation of the inhibitor p21WAF1.

Chemopreventive potential of luteolin during colon carcinogenesis induced by 1,2-dimethylhydrazine
Vaiyapuri Manju, Namasivayam Nalini
The Italian Journal of Biochemistry: 2005; 54(3-4): 268-275

Abstract. We investigated the chemopreventive potential of luteolin on hepatic and circulatory lipid peroxidation and antioxidant status during 1,2-dimethylhydrazine induced colon carcinogenesis in rats. Rats were given a weekly subcutaneous injection of DMH at a dose of 20 mg/kg body weight for 15 weeks. Luteolin (0.2 mg/kg body weight /everyday p.o.) was given at the initiation and also at the postinitiation stages of carcinogenesis to DMH treated rats. The animals were sacrificed at the end of 30 weeks. Enhanced lipid peroxidation in the liver and circulation of tumor bearing rats was accompanied by a significant decrease in the levels of plasma and hepatic reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione-S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), vitamin C, vitamin E and â-carotene in DMH treated rats as compared to the control rats. Intragastric administration of luteolin (0.2mg/kg body weight) to DMH-treated rats significantly reduced the incidence and size of tumor in the colon, reduced lipid peroxidation levels and enhanced the plasma and hepatic activities of GSH, GPx, GST, GR, SOD, CAT, vitamin C, vitamin E and â-carotene. Thus the chemopreventive efficacy of luteolin against colon carcinogenesis is evidenced by our preliminary studies which showed decreased incidence of tumors and the antiperoxidative and antioxidant effect of luteolin. Further study on the exact mechanism of action of luteolin in preventing colon carcinogenesis is yet to be elucidated.

Effects of stratospheric radiations on human glioblastoma cells
Maria Paola Cerù, Fernanda Amicarelli, Loredana Cristiano, Sabrina Colafarina, Pierpaolo Aimola, Stefano Falone, Benedetta Cinque, Ornella Ursini, Roberto Moscardelli, Pietro Ragni
The Italian Journal of Biochemistry: 2005; 54(3-4): 276-286

Abstract. The aim of this work was to evaluate the effect of stratospheric radiations on neural tumour cells. ADF human glioblastoma cells were hosted on a stratospheric balloon within the 2002 biological experiment campaign of the Italian Space Agency. The flight at an average height of 37 km lasted about 24 hrs. Cell morphology, number and viability, cell cycle and apoptosis, some antioxidant enzymes and proteins involved in cell cycle regulation, DNA repair and gene expression were studied. Stratospheric radiations caused a significant decrease in cell number, as well as a block of proliferation, but not apoptosis or necrosis. Radiations also induced activation and induction of some antioxidant enzymes, increase in DNA repair-related proteins (p53 and Proliferating Cell Nuclear Antigen) and variations of the transcription factors Peroxisome Proliferator-Activated Receptors. Morphologically, test cells exhibited more electron dense cytoplasm and less condensed chromatin than controls and modification of their surfaces. Our results indicate that glioblastoma cells, exposed to continuous stratospheric radiations for 24 hrs, show activation of cell cycle check point, decrease of cell number, variations of Peroxisome Proliferator-Activated Receptors and increase of Reactive Oxygen Species-scavenging enzymes.

Torna al n° 4, 2004 | Vai all'Indice di The Italian Journal of Biochemistry

Per chi desidera pubblicare su IJB, sono disponibili le Istruzioni per gli Autori
Per chi desidera sottoscrivere l'abbonamento a IJB, è disponibile la Cedola di Registrazione