Methamphetamine Inhibits the Glucose Uptake by Human Neurons and Astrocytes: Stabilization by Acetyl-L-Carnitine

Methamphetamine (METH), an addictive psycho-stimulant drug exerts euphoric effects on users and abusers. It is also known to cause cognitive impairment and neurotoxicity. Here, we hypothesized that METH exposure impairs the glucose uptake and metabolism in human neurons and astrocytes. Deprivation of glucose is expected to cause neurotoxicity and neuronal degeneration due to depletion of energy. We found that METH exposure inhibited the glucose uptake by neurons and astrocytes, in which neurons were more sensitive to METH than astrocytes in primary culture. Adaptability of these cells to fatty acid oxidation as an alternative source of energy during glucose limitation appeared to regulate this differential sensitivity. Decrease in neuronal glucose uptake by METH was associated with reduction of glucose transporter protein-3 (GLUT3). Surprisingly, METH exposure showed biphasic effects on astrocytic glucose uptake, in which 20 µM increased the uptake while 200 µM inhibited glucose uptake. Dual effects of METH on glucose uptake were paralleled to changes in the expression of astrocytic glucose transporter protein-1 (GLUT1). The adaptive nature of astrocyte to mitochondrial β-oxidation of fatty acid appeared to contribute the survival of astrocytes during METH-induced glucose deprivation. This differential adaptive nature of neurons and astrocytes also governed the differential sensitivity to the toxicity of METH in these brain cells. The effect of acetyl-L-carnitine for enhanced production of ATP from fatty oxidation in glucose-free culture condition validated the adaptive nature of neurons and astrocytes. These findings suggest that deprivation of glucose-derived energy may contribute to neurotoxicity of METH abusers

LDL Receptor Knock-Out Mice Are a Physiological Model Particularly Vulnerable to Study the Onset of Inflammation in Non-Alcoholic Fatty Liver Disease

Non-alcoholic steatohepatitis (NASH) involves steatosis combined with inflammation, which can progress into fibrosis and cirrhosis. Exploring the molecular mechanisms of NASH is highly dependent on the availability of animal models. Currently, the most commonly used animal models for NASH imitate particularly late stages of human disease. Thus, there is a need for an animal model that can be used for investigating the factors that potentiate the inflammatory response within NASH. We have previously shown that 7-day high-fat-high-cholesterol (HFC) feeding induces steatosis and inflammation in both APOE2ki and Ldlr(-/-) mice. However, it is not known whether the early inflammatory response observed in these mice will sustain over time and lead to liver damage. We hypothesized that the inflammatory response in both models is sufficient to induce liver damage over time.APOE2ki and Ldlr(-/-) mice were fed a chow or HFC diet for 3 months. C57Bl6/J mice were used as control.Surprisingly, hepatic inflammation was abolished in APOE2ki mice, while it was sustained in Ldlr(-/-) mice. In addition, increased apoptosis and hepatic fibrosis was only demonstrated in Ldlr(-/-) mice. Finally, bone-marrow-derived-macrophages of Ldlr(-/-) mice showed an increased inflammatory response after oxidized LDL (oxLDL) loading compared to APOE2ki mice.Ldlr(-/-) mice, but not APOE2ki mice, developed sustained hepatic inflammation and liver damage upon long term HFC feeding due to increased sensitivity for oxLDL uptake. Therefore, the Ldlr(-/-) mice are a promising physiological model particularly vulnerable for investigating the onset of hepatic inflammation in non-alcoholic steatohepatitis

Novel Photosensitizers Trigger Rapid Death of Malignant Human Cells and Rodent Tumor Transplants via Lipid Photodamage and Membrane Permeabilization

BACKGROUND: Apoptotic cascades may frequently be impaired in tumor cells; therefore, the approaches to circumvent these obstacles emerge as important therapeutic modalities. METHODOLOGY/PRINCIPAL FINDINGS: Our novel derivatives of chlorin e(6), that is, its amide (compound 2) and boronated amide (compound 5) evoked no dark toxicity and demonstrated a significantly higher photosensitizing efficacy than chlorin e(6) against transplanted aggressive tumors such as B16 melanoma and M-1 sarcoma. Compound 5 showed superior therapeutic potency. Illumination with red light of mammalian tumor cells loaded with 0.1 µM of 5 caused rapid (within the initial minutes) necrosis as determined by propidium iodide staining. The laser confocal microscopy-assisted analysis of cell death revealed the following order of events: prior to illumination, 5 accumulated in Golgi cysternae, endoplasmic reticulum and in some (but not all) lysosomes. In response to light, the reactive oxygen species burst was concomitant with the drop of mitochondrial transmembrane electric potential, the dramatic changes of mitochondrial shape and the loss of integrity of mitochondria and lysosomes. Within 3-4 min post illumination, the plasma membrane became permeable for propidium iodide. Compounds 2 and 5 were one order of magnitude more potent than chlorin e(6) in photodamage of artificial liposomes monitored in a dye release assay. The latter effect depended on the content of non-saturated lipids; in liposomes consisting of saturated lipids no photodamage was detectable. The increased therapeutic efficacy of 5 compared with 2 was attributed to a striking difference in the ability of these photosensitizers to permeate through hydrophobic membrane interior as evidenced by measurements of voltage jump-induced relaxation of transmembrane current on planar lipid bilayers. CONCLUSIONS/SIGNIFICANCE: The multimembrane photodestruction and cell necrosis induced by photoactivation of 2 and 5 are directly associated with membrane permeabilization caused by lipid photodamage

Basic Science of Liver Cancer Stem Cells and Hepatocarcinogenesis

The basic science of liver cancer stem cells (LCSCs) and hepatocarcinogenesis is best understood by familiarity with the increasingly complex epidemiology of hepatocellular carcinoma (HCC), with the still unknown cell origin(s) of HCC, with the anatomy and function of the liver lobule and with the historical and some novel methods for the study and identification of adult tissue stem cells and LCSCs

Organ-specific autoimmunity and genetic predisposition in interferon-treated HCV-related chronic hepatitis patients

Abstract: Aims. Interferon alpha has been reported to enhance autoantibody production and to increase the risk of autoimmunity particularly against thyroid tissue. We designed a study with the following aims: 1) to assess the incidence of organ- and non-organ-specific autoantibodies during Interferon treatment; 2) to evaluate whether these autoantibodies have any clinical relevance; 3) to establish whether the development of autoimmune disorders can be related to a genetic predisposition. Methods. A panel of 5 non-organ-specific and 6 organ-specific autoantibodies was evaluated in serum samples collected before treatment and then at 3 and 12 months in 47 patients enrolled in a treatment protocol with a 2b-recombinant Interferon (3 MU, 3 times a week for 12 months). III the second part of the study we explored genetic predisposition for autoimmune disorders in 31 patients by DNA-HLA class II typing rising Restriction Fragment Length Polymorphism (RFPL). Results. Non-organ-specific autoantibodies were absent in all patients before and after Interferon. During follow-up 6 patients showed an increment in thyroid microsomal antibody titres; 3 of these also developed thyroglobulin autoantibodies; 3 of the 6 patients developed persistent hypothyroidism; a fourth had a transient subclinical hypothyroidism and a fifth had a transient subclinical hyperthyroidism. Two patients with initial positivity for ICA and PCA maintained their reactivity during treatment without impairment of the respective target organs. Eight out of 39 initially negative patients developed one or more organ-specific autoantibodies during follow-up. One of these developed a persistent hypothyroidism, and another developed insulin-dependent diabetes. HLA-typing did not reveal any particular allele frequency in patients with thyroid antibody positivity as compared with those without autoantibodies and controls. Moreover four of the 6 patients positive for islet-cell antibodies were carrying the non-Asp 57 allele which is considered a marker of a genetic predisposition for insulin-dependent diabetes. Conclusions: These findings suggest that besides the thyroid gland, pancreatic beta-cells could be a target of autoimmunity, during Interferon-treatment for chronic HCV hepatitis. A genetic predisposition may be important, though insufficient alone, in the development of Interferon-induced autoimmune phenomena

Risk margin estimation through the cost of capital approach: some conceptual issues

The Solvency II directive requires that insurance liabilities are valued using a best estimate plus a risk margin. The risk margin should be estimated using the cost of capital approach,that is the cost of the solvency capital requirement\u2014which is computed through a value at risk measure\u2014needed to support the insurance obligation until settlement. The unitary cost of capital applied to the future capital requirement should be fixed. This paper deals with conceptual issues relating to the risk margin estimate through the cost of capital approach. It shows that the Solvency II specification of the methodology is consistent with financial economics. However, the theoretical framework required (a frictionless and normally distributed world) is too far-fetched to be acceptable. Even if these conditions were satisfied, a variable unitary cost of capital must be used