Insulin secretion is controlled by mGlu5 metabotropic glutamate receptors

Recent evidence suggests that metabotropic glutamate (mGlu) receptors are involved in the regulation of hormone secretion in the endocrine pancreas. We report here that endogenous activation of mGlu5 receptors is required for an optimal insulin response to glucose both in clonal beta-cells and in mice. In clonal beta-cells, mGlu5 receptors were expressed at the cell surface and were also found in purified insulin-containing granules. These cells did not respond to a battery of mGlu5 receptor agonists that act extracellularly, but instead responded to a cell-permeant analog of glutamate with an increase in [Ca2+]i and insulin secretion. Both effects were largely attenuated by the mGlu5 receptor antagonist, 2-methyl-6-(phenylethynyl)-pyridine (MPEP). MPEP and its structural analog, (E)-2-methyl-6-styryl-pyridine (SIB-1893), reduced the increase in [Ca2+]i and insulin secretion induced by glucose in clonal beta-cells, whereas a mGlu1 receptor antagonist was inactive. mGlu5 knockout mice showed a defective insulin response at all times after a glucose pulse (1.5 g/kg, i.p.), whereas wild-type mice treated with MPEP (10 mg/kg, i.p.) showed a selective impairment in the late phase of insulin secretion in response to glucose challenge. Mice injected with MPEP or lacking mGlu5 receptors also showed a blunted glucagon response to an insulin challenge. We conclude that insulin secretion is under the control of mGlu5 receptors both in clonal beta-cells and in vivo. Drugs that modulate the function of mGlu5 receptors might affect glucose homeostasis by altering the secretion of pancreatic hormones.     

Emergence of Toscana virus in Europe

Toscana virus (TOSV) is an arthropod-borne virus first identified in 1971 from the sandfly Phlebotomus perniciosus in central Italy. Many case reports in travelers and clinical research and epidemiologic studies conducted around the Mediterranean region have shown that TOSV has a tropism for the central nervous system (CNS) and is a major cause of meningitis and encephalitis in countries in which it circulates. In central Italy, TOSV is the most frequent cause of meningitis from May to October, far exceeding enteroviruses. In other northern Mediterranean countries, TOSV is among the 3 most prevalent viruses associated with meningitis during the warm seasons. Therefore, TOSV must be considered an emerging pathogen. Here, we review the epidemiology of TOSV in Europe and determine questions that should be addressed in future studies. Despite increasing evidence of its major role in medicine as an emerging cause of CNS infections, TOSV remains an unstudied pathogen, and few physicians are aware of its potential to cause CNS infections.     

Mammalian Metabolism of β-Carotene: Gaps in Knowledge

β-carotene is the most abundant provitamin A carotenoid in human diet and tissues. It exerts a number of beneficial functions in mammals, including humans, owing to its ability to generate vitamin A as well as to emerging crucial signaling functions of its metabolites. Even though β-carotene is generally considered a safer form of vitamin A due to its highly regulated intestinal absorption, detrimental effects have also been ascribed to its intake, at least under specific circumstances. A better understanding of the metabolism of β-carotene is still needed to unequivocally discriminate the conditions under which it may exert beneficial or detrimental effects on human health and thus to enable the formulation of dietary recommendations adequate for different groups of individuals and populations worldwide. Here we provide a general overview of the metabolism of this vitamin A precursor in mammals with the aim of identifying the gaps in knowledge that call for immediate attention. We highlight the main questions that remain to be answered in regards to the cleavage, uptake, extracellular and intracellular transport of β-carotene as well as the interactions between the metabolism of β-carotene and that of other macronutrients such as lipids.     

Homology modelling and docking studies on Varicella Zoster Virus Thymidine kinase

Thymidine kinase (TK) is the key enzyme in antiviral and suicide gene therapies. While herpes simplex virus type 1 thymidine kinase has been widely studied and crystallised less is known on Varicella Zoster Virus thymidine kinase (VZV TK) and its three-dimensional structure. In this paper we report the model of the three-dimensional structure of VZV TK resulting from a homology modelling study. Subsequent docking studies of the natural substrate deoxythymidine (dT) and known antiviral drugs were performed and shaded new light on the binding characteristics of the enzyme.     

Homocysteine and cognitive function in healthy elderly community dwellers in Italy

BACKGROUND: Elevated plasma total homocysteine (tHcy) concentrations are common in the elderly and have been suggested to be a risk factor for dementia. OBJECTIVE: In an elderly population, we examined the relation between plasma tHcy and scores on the Mini-Mental State Examination (MMSE), a commonly used screening measure of cognitive impairment in general practice. DESIGN: Fasting plasma tHcy concentrations were measured in 650 healthy, cognitively normal Italian community dwellers aged > or = 65 y (x +/- SD: 72.8 +/- 6.0 y). Socioeconomic status; serum folate, vitamin B-12, and creatinine; other potential dietary and lifestyle determinants of tHcy; and conventional vascular disease risk factors were also assessed. RESULTS: Subjects with MMSE scores of 26-28 had higher plasma tHcy concentrations (12.7 micromol/L; range: 12.2-13.2 micromol/L) than did those with scores > 28 (11.9 micromol/L; 11.4-12.3 micromol/L; P < 0.01). Subjects with scores of 24-25 had higher plasma tHcy concentrations (14.5 micro mol/L; 13.5-15.6 micromol/L) than did subjects with scores of 26-28 (P < 0.01) or > 28 (P < 0.001). The risk of hyperhomocysteinemia (plasma tHcy > 15 micromol/L) was higher in subjects with scores of 24-25 (odds ratio: 3.81; 95% CI: 1.9, 7.5) or 26-28 (odds ratio: 1.96; 95% CI: 1.3, 3.0) than in those with scores > 28. The results did not change after adjustment for conventional vascular risk factors and for age, medical, dietary, and lifestyle determinants of plasma tHcy. CONCLUSION: Elevated plasma tHcy has an independent, graded association with concurrent cognitive impairment as measured with the MMSE in healthy elderly community dwellers.     

New platinum(II) complexes containing both an O,O'-chelated acetylacetonate ligand and a sulfur ligand in the platinum coordination sphere induce apoptosis in HeLa cervical carcinoma cells

We report the cytotoxic effects obtained in HeLa cells of three newly synthesized platinum complexes containing both an O,O'-chelated acetylacetonate ligand and a sulfur ligand in the platinum coordination sphere, which show, by (1)H NMR, negligible reactivity with purine bases. These compounds induce cell death with [Pt(O,O'-acac)(gamma-acac)(DMS)] being the most effective (IC(50)=0.98+/-0.056 and 1.82+/-0.023 microM for [Pt(O,O'-acac)(gamma-acac)(DMS)] and cisplatin, respectively). About 50% of cells died after 5h treatment with 100 microM [Pt(O,O'-acac)(gamma-acac)(DMS)] whilst a 16 h incubation was required to get the same results using 100 microM cisplatin. Cellular accumulation measurements, after treatment with equimolar drug concentrations, indicated the major lipophilicity and cellular uptake of the new compounds. While the cytotoxicity of cisplatin was due to both intracellular accumulation and DNA binding, that of [Pt(O,O'-acac)(gamma-acac)(DMS)] was associated with intracellular Pt accumulation only, since it has low reactivity to DNA in intact cells and in vitro. The reaction of the new complexes with guanosine and 5'-GMP was negligible, whereas the L-methionine instantly reacted with the initial Pt complexes. Both cisplatin and [Pt(O,O'-acac)(gamma-acac)(DMS)] induced apoptosis in HeLa cells. [Pt(O,O'-acac)(gamma-acac)(DMS)] provoked the early signs of apoptosis induction (cleavage of PARP and activation of caspases-9, -3 and -7) only 1h after addition of the drug. However, in cisplatin-treated cells, cleavage of PARP was seen after 9h with activation of caspases also proceeding more slowly. In conclusion, these results indicate that the newly synthesized platinum(II) complexes have high and rapid cytotoxic activity in vitro, and suggest that DNA may not be their primary target.     

Alpha-tocopherol protects against cisplatin-induced toxicity without interfering with antitumor efficacy

Our aim was 2-fold: to investigate the role of alpha-tocopherol supplementation on the antitumor activity of DDP and to evaluate the effect of alpha-tocopherol on the survival and neurotoxicity of DDP-treated mice. Experiments performed on the M14 human melanoma line demonstrated that alpha-tocopherol supplementation did not influence the efficacy of DDP; the inhibition of cell survival and of the in vivo tumor growth after treatment with alpha-tocopherol and DDP combination was similar to that observed after DDP alone. Conversely, alpha-tocopherol was also able to increase survival of mice treated with a high dose of DDP. While DDP alone produced death in about 70% of mice, the combination reduced deaths to about 30%. Analysis of oxidative stress markers and peroxidative damage in organs indicated that the protective effect of alpha-tocopherol was mainly related to its antioxidant activity. A significant increase in the concentration of TBARS and decreased PUFAs and catalase activity were observed after DDP treatment, while with alpha-tocopherol the levels of these markers were comparable to those observed in untreated mice. Histologic analysis performed on peripheral nerve revealed that alpha-tocopherol also protected mice from severe neurologic damage induced by DDP treatment. In conclusion, our results demonstrate that alpha-tocopherol protects against the systemic toxicity and neurotoxicity induced by DDP without interfering with its antitumor activity and suggest that this combination is a promising strategy to improve the therapeutic index of DDP-based chemotherapy.     

HER-2/neu assessment in primary chemotherapy treated breast carcinoma: no evidence of gene profile changing

HER-2/neu protein expression and gene amplification were analyzed in a series of 85 consecutive breast carcinoma patients entered into an adriamicin/taxol primary chemotherapy trial followed by surgery, 45 of whom underwent pre-treatment fine needle aspirate (FNA). Dual color FISH (fluorescent in situ hybridization) assay revealed high-level HER-2/neu gene amplification in the immunocytochemistry (ICC) indicated 3+ cases and no, low or moderate amplification in the ICC 2+ group, consistent with previous findings in untreated patients series. Results obtained with the ICC assay CB 11 showed higher overall concordance with FISH than did the Herceptest ICC assay, but CB 11 was less accurate than Herceptest in terms of selecting patients suitable for Herceptin treatment, which is currently restricted to ICC 3+/FISH amplified patients. The only ICC 3+ low-level amplified case (non-amplified according the two more stringent criteria applied) was found with the CB 11 assay. Comparison between pre-treatment smears and post-treatment sections by FISH revealed no significant changes in the HER-2/neu gene profile. In the clinical setting these findings point to the usefulness of HER-2/neu assessment in chemotherapy-treated patients, when pre-treatment material is unavailable.     

N-Acetyltransferase-2, glutathione S-transferase M1 and T1 genetic polymorphisms, cigarette smoking and hepatocellular carcinoma: a case-control study

Our aim was to evaluate the role of N-acetyltransferase (NAT2) and glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) polymorphisms in hepatocellular carcinoma (HCC) according to cigarette smoking, taking into account hepatitis B (HBV) and C (HCV) viral infection as well as alcohol consumption. A hospital-based case-control study was conducted in 2 areas of north Italy. Cases (n = 200) were patients hospitalized for HCC, and controls (n = 400) were patients admitted for reasons other than liver disease, neoplasms and tobacco- and alcohol-related diseases. Genotypes were determined using PCR and the PCR/restriction fragment length polymorphism-based method. The putative risk genotypes NAT2 slow acetylator, GSTM1 null and GSTT1 null were not associated with HCC (OR = 1.3, 95% CI 0.8-2.0; OR = 1.0, 95% CI 0.6-1.5; OR = 0.8, 95% CI 0.4-1.4, respectively). Although not statistically significant, an increase in HCC risk was observed among light smokers (1-20 pack-years) carrying GSTT1 null (OR = 1.7, 95% CI 0.6-4.7) and NAT2 slow acetylator (OR = 1.3, 95% CI 0.6-3.0) genotypes. In conclusion, there was no evidence for a gene-environment interaction in HCC risk for GSTM1, GSTT1 and NAT2 genotypes.