Franco Santangelo

Evidence for secretion of cytosolic CuZn superoxide dismutase by Hep G2 cells and human fibroblasts

The role so far ascribed to intracellular CuZn superoxide dismutase is that of an intracellular scavenger of oxygen radicals. However, other functions of cytosolic CuZn superoxide dismutase have been hypothesized. For example, CuZn superoxide dismutase incubated with rat hepatocyte cells in culture inhibits 3-hydroxy-3methylglutaryl CoA reductase, thereby reducing cholesterol synthesis. We recently demonstrated the presence of surface membrane receptors for CuZn superoxide dismutase, suggesting possible autocrine or paracrine activities. The aim of the present study was to investigate whether cytosolic CuZn superoxide dismutase can be secreted by human hepatocarcinoma and fibroblast cells lines. Proteins in human hepatocellular carcinoma (Hep G2) cells and human fibroblasts were biosynthetically labelled with [35S]-cysteine; then cell lysates and media were immunoprecipitated with rabbit polyclonal anti-human CuZn superoxide dismutase antibodies and separated by 12% polyacrylamide gel electrophoresis. Both Hep G2 cells and human fibroblasts produce and secrete CuZn superoxide dismutase which was detectable in cells and medium as a single protein band with the same electrophoretic mobility as human erythrocyte CuZn superoxide dismutase. These data suggest that CuZn superoxide dismutase, an enzyme thus far considered to be located exclusively intracellularly is secreted by at least two cell lines. This is consistent with autocrine or paracrine roles for CuZn superoxide dismutase.

Circadian rhythms of lipid and apolipoprotein pattern in adult fasted rats

Data on circadian rhythms of serum lipids and apolipoproteins in animals and in human subjects are scarce. The goal of this study was to investigate the existence of circadian rhythms in the lipids and apolipoproteins of fasted rats. We showed that in fasted rats well-defined circadian rhythms were present in total serum triglycerides and in cholesterol and triglycerides of very low density lipoprotein (VLDL), intermediate density lipoprotein-low density lipoprotein (IDL-LDL) and high density lipoprotein (HDL). Moreover, our data clearly show that the circadian rhythm of lipoproteins is accompanied by a well defined circadian rhythm of B apoprotein, in all lipoprotein classes examined.

Thymus fraction (FIII) Effect on cholesterol metabolism: Modulation of the low density lipoprotein receptor pathway

1. A heat stable protein fraction from calf thymus is able to determine a marked drop of total serum cholesterol and B apoproteins in rats fed a cholesterol enriched diet. 2. It is known that the catabolism of low density lipoprotein (LDL) cholesterol is mediated by the existence of high affinity surface receptor on membrane cells. 3. The purpose of the present paper is to verify if the heat stable thymus protein fraction is able to affect the LDL receptor pathway in vitro. 4. The results obtained show that the protein calf thymus is able to increase human and rat LDL catabolism.

The effect of L-carnitine on the apolipoprotein pattern of rats fed a cholesterol-rich diet

1. L-Carnitine was administered to hypercholesterolemic rats for eight days, after which the blood was collected by intracardiac puncture and lipoproteins were collected by preparative ultracentrifuge. 2. The chemical composition of lipoproteins of normal rats and hypercholesterolemic rats before and after L-carnitine treatment was determined. 3. The total serum B and E apoproteins were assayed by rocket electrophoresis, while apoproteins in VLDL, IDL, LDL and HDL were determined by densitometric scanning of SDS and TMU polyacrylamide disc gel electrophoresis. 4. The results obtained showed that the L-carnitine treatment tends to restore to normal values both the chemical composition of lipoproteins and the apoproteins pattern of rats fed on a diet enriched with cholesterol.

Enhancement of tissue lipoperoxidation in propanil-treated rats.

The i.p. injection of the herbicide propanil to male Sprague-Dawley rats increased the susceptibility to lipoperoxidation of liver and brain rat microsomes. A liver damage produced by propanil treatment was demonstrated by decreased serum levels of cholesterol and triglycerides as compared to serum levels of the lipids in control rats. The cellular damage of rat liver was also confirmed by the increased serum levels of aspartate aminotransferase and alkaline phosphatase activities observed in propanil-treated rats as compared to their activities in control rats.

Purification and characterization of a calf thymus protein active on lipid metabolism

1. This work concerns the purification of a calf thymus protein that increases the binding of human 125I-labeled low density lipoprotein (LDL) on both human skin fibroblasts and a special line of rat liver cells, BRL 3A. 2. It was found that the thymus gland affects cholesterol metabolism via an activation of the LDL receptor pathway. 3. Moreover, the thymus protein active on the LDL receptor pathway has a different amino acid composition and molecular weight from other well-characterized thymic peptides.

Neuropsychological correlates of Pisa syndrome in patients with Parkinson's disease

A complex relationship exists between postural control and cognition in the elderly. Namely, neural mechanisms that are required for the regulation of posture have been variably associated with cognitive dysfunctions. Parkinsons disease (PD) is the second most common neurodegenerative disease among the elderly, and it has been associated with both cognitive and postural abnormalities such as Pisa syndrome (PS). Although its onset has been considered to be multifactorial, the pathophysiological mechanisms underpinning PS are still not fully explained. Until now, no study investigated the possible contribution of cognitive dysfunction to occurrence of PS in PD.

Role of a calf thymus preparation in the degradation of native and reductively methylated low density lipoprotein

1. The clearance of low density lipoprotein (LDL) is mediated by a specific LDL receptor pathway and by an alternative metabolic pathway that is responsible for the receptor-independent LDL catabolism. 2. This alternative catabolism can be studied in vivo using a preparation of chemically modified LDL that are reductively methylated. 3. Recently we showed that a calf thymus protein extract affects the cholesterol metabolism via activation of LDL catabolism. 4. The aim of this study was to investigate whether in vivo the specific LDL receptor pathway and the independent LDL receptor pathway are affected by thymus treatment. 5. The results obtained injecting in rats native and chemically modified 125I-LDL to probe the receptor independent pathway, show that the thymus gland decreases serum cholesterol by activation of the specific LDL receptor pathway. 6. This effect is mainly evident in liver and kidney that represent organs in which the specific LDL receptors are widely present.

The calf superoxide dismutase receptor of rat hepatocytes

The presence of a specific SOD surface membrane receptor in rat hepatocyte cells was investigated using ligand blot analysis of the SOD receptor with 125I-SOD, and binding studies with iodinated and fluorescinated SOD. A specific SOD receptor with a molecular weight of about 320 kDa was identified. We suggest that the modulatory role of SOD on HMG-CoA reductase is exerted through this specific receptor.

Effects of a new calf thymus protein on 3-hydroxy3-methylglutaryl-CoA reductase activity in rat (rattus bubalus) hepatocyte cells (BRL-3A)

1. In a previous paper we described the purification steps of a new calf thymus protein able to activate the LDL receptor catabolism. 2. In this paper we examine the modulatory effect of this new calf thymus protein on 3HMG-CoA reductase activity in rat hepatocyte cells to better clarify the role of this protein on cholesterol metabolism. 3. The results obtained show that the calf thymus protein inhibits the HMG-CoA reductase, and support the hypothesis that the activation of LDL receptor catabolism is mediated by a decreased amount of cellular cholesterol following HMG-CoA reductase inhibition.