Synthesis and SAR studies of a novel series of T-type calcium channel blockers

For the novel, potent, and selective T-type Ca2+ channel blockers, a series of sulfonamido-containing 3,4-dihydroquinazoline derivatives were prepared and evaluated for their blocking actions on T- and N-type Ca2+ channels. Among them, 9c (KYS05064, IC50 = 0.96 +/- 0.22 microM) was found to be as potent as Mibefradil and also showed the highest selectivity for T-type Ca2+ channel with no effect on N-type Ca2+ channel.     

Dyrk1A phosphorylates alpha-synuclein and enhances intracellular inclusion formation

Lewy bodies (LBs) are pathological hallmarks of Parkinson disease (PD) but also occur in Alzheimer disease (AD) and dementia of LBs. Alpha-synuclein, the major component of LBs, is observed in the brain of Down syndrome (DS) patients with AD. Dyrk1A, a dual specificity tyrosine-regulated kinase (Dyrk) family member, is the mammalian ortholog of the Drosophila minibrain (Mnb) gene, essential for normal postembryonic neurogenesis. The Dyrk1A gene resides in the human chromosome 21q22.2 region, which is associated with DS anomalies, including mental retardation. In this study, we examined whether Dyrk1A interacts with alpha-synuclein and subsequently affects intracellular alpha-synuclein inclusion formation in immortalized hippocampal neuronal (H19-7) cells. Dyrk1A selectively binds to alpha-synuclein in transformed and primary neuronal cells. Alpha-synuclein overexpression, followed by basic fibroblast growth factor-induced neuronal differentiation, resulted in cell death. We observed that accompanying cell death was increased alpha-synuclein phosphorylation and intracytoplasmic aggregation. In addition, the transfection of kinase-inactive Dyrk1A or Dyrk1A small interfering RNA blocked alpha-synuclein phosphorylation and aggregate formation. In vitro kinase assay of anti-Dyrk1A immunocomplexes demonstrated that Dyrk1A could phosphorylate alpha-synuclein at Ser-87. Furthermore, aggregates formed by phosphorylated alpha-synuclein have a distinct morphology and are more neurotoxic compared with aggregates composed of unmodified wild type alpha-synuclein. These findings suggest alpha-synuclein inclusion formation regulated by Dyrk1A, potentially affecting neuronal cell viability.     

Cellular action of cholecystokinin-8S-mediated excitatory effects in the rat periaqueductal gray

The peptide cholecystokinin (CCK) is one of the major neurotransmitters modulating satiety, nociception, and anxiety behavior. Although many behavioral studies showing anti-analgesic and anxiogenic actions of CCK have been reported, less is known about its cellular action in the central nervous system (CNS). Therefore, we examined the action of CCK in rat dorsolateral periaqueductal gray (PAG) neurons using slice preparations and whole-cell patch-clamp recordings. Application of CCK-8S produced an inward current accompanied by increased spontaneous synaptic activities. The CCK-8S-induced inward current (I(CCK)) was recovered after washout and reproduced by multiple exposures. Current-voltage plots revealed that I(CCK) reversed near the equilibrium potential for K(+) ions with a decreased membrane conductance. When several K(+) channel blockers were used, application of CdCl(2), TEA, or apamin significantly reduced I(CCK). I(CCK) was also significantly reduced by the CCK(2) receptor antagonist, L-365,260, while it was not affected by the CCK(1) receptor antagonist, L-364,718. Furthermore, we examined the effects of CCK-8S on miniature excitatory postsynaptic currents (mEPSCs) in order to determine the mechanism of CCK-mediated increase on synaptic activities. We found that CCK-8S increased the frequency of mEPSCs, but had no effect on mEPSC amplitude. This presynaptic effect persisted in the presence of CdCl(2) or Ca(2+)-free bath solution, but was completely abolished by pre-treatment with BAPTA-AM, thapsigargin or L-365,260. Taken together, our results indicate that CCK can excite PAG neurons at both pre- and postsynaptic loci via the activation of CCK(2) receptors. These effects may be important for the effects of CCK on behavior and autonomic function that are mediated via PAG neurons.     

Methylated DNA/RNA in Body Fluids as Biomarkers for Lung Cancer

DNA/RNA methylation plays an important role in lung cancer initiation and progression. Liquid biopsy makes use of cells, nucleotides and proteins released from tumor cells into body fluids to help with cancer diagnosis and prognosis. Methylation of circulating tumor DNA (ctDNA) has gained increasing attention as biomarkers for lung cancer. Here we briefly introduce the biological basis and detection method of ctDNA methylation, and review various applications of methylated DNA in body fluids in lung cancer screening, diagnosis, prognosis, monitoring and treatment prediction. We also discuss the emerging role of RNA methylation as biomarkers for cancer.     

Quantitative biochemical characterization and biotechnological production of caspase modulator,XIAP: Therapeutic implications for apoptosis-associated diseases

Background

Regulating apoptosis is a common and essential therapeutic strategy for cancer and neurodegenerative disorders. Based on basic studies of apoptotic mechanisms, various researches have attempted to overcome the pathogenesis of such diseases by activating or inhibiting apoptosis. Generally, the biochemical characteristics of the target molecules should be evaluated along with understanding of their mechanisms of action during drug development. Among apoptotic regulators, XIAP serves as a potent negative regulator to block apoptosis through the inhibition of caspase (CASP)-9 and -3/7. Although XIAP is an attractive target with such apoptotic-modulating property, biochemical and biophysical studies of XIAP are still challenging.

Adverse effects of tempol on hidrosaline balance in rats with acute sodium overload

We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis.     

Transient transfection of mammalian cells with DNA of the plant-pathogenic Ti-plasmid and expression of marker and resident sequences

Summary The large Ti-plasmid from Agrobacterium tumefaciens strain C58 has been used for transfection experiments with mammalian cells. In DNA from Tupaia baby fibroblasts Ti-plasmid sequences could be identified by filter hybridization as long as four weeks after transfection including two cell passages. The hybridization signals decreased rapidly after addition of the Ti-plasmid DNA-coprecipitate to the cells. The signals were often not detected any more after the first day, but were visible one week after transfection. Nuclei prepared from Ti-plasmid-transfected cells hybridized to pTi-specific RNA. With the chloramphenicol acetyl transferase-gene as marker no discrimination in DNA uptake was found between the Ti-plasmid and much smaller plasmids. According to the number of nuclei with homology to pTi-sequences it is assumed that about 0.2% of the cells carry Ti-plasmid DNA in the nucleus. Analysis of RNA isolated from cells transfected with cloned segments of the Ti-plasmid revealed that the TDNA region of the Ti-plasmid was predominantly transcribed.Abbreviations CAT Chloramphenicol Acetyl Transferase - NPT Neomycin Phosphotransferase - SDS Sodium Dodecylsulfate - TK Thymidine Kinase     

Antigenicity of carcinogen and viral induced sarcomas in inbred and random bred guinea pigs.

A tumor specific transplantation antigen (TSTA) has been detected in a methylcholanthrene (MCA) induced guinea pig tumor. It was possible to induce resistance to rechallenge with the tumor by immunization with irradiated cells in CFA. In contrast, the same technique failed to detect TSTA in two viral (Kirsten strain mouse sarcoma virus, Ki-MSV) induced guinea pig tumors; these results are similar to observations made with mouse Ki-MSV-induced tumors. Transplantation studies with these tumors in both inbred and random-bred guinea pigs showed a complexity of growth and rejection patterns. The B alloantigen, a major serologically defined antigen of the guinea pig histocompatibility complex, seemed to play a central role in acting as a guniea pig transplantation antigen. In all cases studied, the absence of B antigens in the recipient led to tumor rejection and anti-B antibody protection.