Pharmacological doses of melatonin impede cognitive decline in tau‐related Alzheimer models,once tauopathy is initiated,by restoring the autophagic flux

Alterations in autophagy are increasingly being recognized in the pathogenesis of proteinopathies like Alzheimer's disease (AD). This study was conducted to evaluate whether melatonin treatment could provide beneficial effects in an Alzheimer model related to tauopathy by improving the autophagic flux and, thereby, prevent cognitive decline. The injection of AAV‐hTau^P301L viral vectors and treatment/injection with okadaic acid were used to achieve mouse and human ex vivo, and in vivo tau‐related models. Melatonin (10 μmol/L) impeded oxidative stress, tau hyperphosphorylation, and cell death by restoring autophagy flux in the ex vivo models. In the in vivo studies, intracerebroventricular injection of AAV‐hTau^P301L increased oxidative stress, neuroinflammation, and tau hyperphosphorylation in the hippocampus 7 days after the injection, without inducing cognitive impairment; however, when animals were maintained for 28 days, cognitive decline was apparent. Interestingly, late melatonin treatment (10 mg/kg), starting once the alterations mentioned above were established (from day 7 to day 28), reduced oxidative stress, neuroinflammation, tau hyperphosphorylation, and caspase‐3 activation; these observations correlated with restoration of the autophagy flux and memory improvement. This study highlights the importance of autophagic dysregulation in tauopathy and how administration of pharmacological doses of melatonin, once tauopathy is initiated, can restore the autophagy flux, reduce proteinopathy, and prevent cognitive decline. We therefore propose exogenous melatonin supplementation or the development of melatonin derivatives to improve autophagy flux for the treatment of proteinopathies like AD.     

Microbial transformation of azacarbazoles. I. N-methylation of alpha-, beta-, and gamma-carbolines by Kitasatosporia setae strain

Microbial transformation of selected azacarbazoles, compounds noted for their activity as antitumor agents, conducted with Kitasatosporia setae strain resulted in N-methylation of pyridine nucleus of alpha-, beta- and gamma-carboline molecule. Formed quaternized intermediates were converted in alkaline conditions into corresponding iso-carbolines. The structure of the final products, alpha-, beta- and gamma-iso-carbolines have been established on the basis of spectral data and confirmed by chemical synthesis.     

Sirolimus and mycophenolate mofetil as calcineurin inhibitor-free immunosuppression in a cardiac transplant patient with chronic renal failure.

Chronic renal failure triggered by calcineurin inhibitor (CNI)-based immunosuppression is a common complication after cardiac transplantation. Sirolimus and mycophenolate mofetil (MMF) are 2 newer immunosuppressive agents with no documented nephrotoxic side effects. This case report describes a patient with ongoing chronic renal failure 10 months after cardiac transplantation on cyclosporine-based immunosuppressive therapy. Conversion of the immunosuppressive regimen from cyclosporine to sirolimus and MMF resulted in freedom from acute rejection, excellent cardiac graft function and consistently improved renal function. This case illustrates the beneficial potential of sirolimus and MMF as CNI-free and safe long-term immunosuppression in a patient with chronic renal failure after heart transplantation.     

Residual cholesterol synthesis and simvastatin induction of cholesterol synthesis in Smith-Lemli-Opitz syndrome fibroblasts

Smith-Lemli-Opitz syndrome (RSH/SLOS) is an autosomal recessive, malformation syndrome caused by mutations in the 3beta-hydroxysterol delta7-reductase gene (DHCR7). DHCR7 catalyzes the reduction of 7-dehydrocholesterol (7DHC) to cholesterol. We report the mutation analysis and determination of residual cholesterol synthesis in 47 SLOS patients, and the effects of treatment of SLOS skin fibroblasts with simvastatin. Using deuterium labeling we have quantified the amount of synthesized cholesterol and 7DHC in homozygote, heterozygote, and control fibroblast cell lines. In SLOS fibroblasts, the fraction of synthesized cholesterol to total sterol synthesis ranged from undetectable to over 50%. This establishes that different mutant alleles encode enzymes with varying degrees of residual activity. There was a correlation between increased phenotypic severity and decreased residual cholesterol synthesis (r(2)=0.45, p<0.0001). Simvastatin treatment of SLOS fibroblasts with residual DHCR7 enzymatic activity decreased 7DHC levels and increased cholesterol synthesis. This increase in cholesterol synthesis is due to increased expression of a mutant allele with residual function. Determination of residual enzymatic activity for specific DHCR7 mutant alleles will help in understanding the processes underlying the broad phenotypic spectrum found in this disorder and will be useful in identifying patients who may benefit from simvastatin therapy.     

Microbial transformation of azacarbazoles. IX. Preliminary studies on hydroxylation of 2,3-benzo-1,4-dimethyl-alpha-iso-carboline by Paecilomyces flavinosus

Microbial transformation of 2,3-benzo-1,4-dimethyl-alpha-iso-carboline performed with several strains of fungi Beauveria bassiana, Verticillum lecani and Paecilomyces flavinosus yielded common products which were expected to be hydroxylated derivatives of starting compound. Among the microorganisms tested, strain Paecilomyces flavinosus P-5 was selected to perform quantitative bioconversion of 2,3-benzo-1,4-dimethyl-alpha-iso-carboline for preparative scale.     

Evidence that orexins A and B stimulate insulin secretion from rat pancreatic islets via both receptor subtypes

Orexins are recently identified neuropeptides that appear to play a role in the regulation of energy homeostasis and arousal. They bind to and activate two closely related G protein-coupled receptors (OXR1 and OXR2), previously described as orphans. In this study we examined involvement of orexins in regulation of insulin secretion from rat pancreatic islets utilizing an in situ perfused pancreas and isolated pancreatic islet models. By means of RT-PCR we found that both OXR1 and OXR2 are expressed in rat pancreatic islets. Furthermore, the expression levels of OXR1 were higher than OXR2. In both experimental models applied, orexins A and B (1, 10 and 100 nmol/l) concentration dependently stimulated insulin secretion at two different glucose concentrations (6.66 or 26.4 mmol/l), with orexin A being more potent than orexin B. This study demonstrates that orexins A and B modulate insulin secretion in vitro.     

Calcium/phosphatidylserine/diacylglycerol-dependent protein phosphorylation in the Aplysia nervous system

It has been shown that intracellular injection of protein kinase C (calcium/phosphatidylserine/diacylglycerol-dependent protein kinase), purified from mammalian brain, or application of the tumor-promoting phorbol diester, 12-O-tetradecanoyl-13-phorbol acetate (TPA), leads to an enhancement of calcium currents in the bag cell neurons of Aplysia. We now present evidence of an endogenous enzyme in bag cell neurons which is activated by TPA and which has properties similar to those of mammalian protein kinase C. Calcium/phosphatidylserine/diacylglycerol-dependent protein kinase activity was found in both cytosolic and particulate fractions prepared from isolated clusters of bag cell neurons. This endogenous enzyme phosphorylated an 87,000-dalton protein from bovine brain, which appears to be a specific substrate for protein kinase C, as well as several substrates present in cytosolic fractions prepared from isolated bag cell clusters. Similar results were obtained using preparations made from pooled head ganglia from Aplysia. The pharmacological properties of the calcium/phosphatidylserine/diacylglycerol-dependent protein kinase activity in the Aplysia nervous system were similar to those of protein kinase C from mammalian tissues. Thus, the same group of endogenous substrate proteins were phosphorylated when diacylglycerol was replaced by TPA in cytosolic fractions prepared from isolated bag cell clusters. Non-tumor-promoting phorbols (4-alpha-phorbol, 4-alpha-phorbol-12,13-didecanoate, and 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate) did not stimulate protein phosphorylation in these preparations. Phosphorylation by the Aplysia calcium/phosphatidylserine/diacylglycerol-dependent protein kinase was inhibited by polymixin B sulfate, by calmodulin, and by the "calmodulin antagonists" trifluoperazine, calmidazolium and W7.(ABSTRACT TRUNCATED AT 250 WORDS)