Chromosaponin I stimulates the growth of lettuce roots

A γ-pyronyl triterpenoid saponin termed chromosaponin 1 (CSI), a conjugate of soyasaponin I and γ-pyrone, was found at 3 mM to stimulate the growth of lettuce root ( Lactuca sativa L. ev. Grand Rapids) to about 190% of the control. Since CSI is an amphipathic reductant, the stimulating effect of this saponin was compared with other reductants and other surface-active compounds. Trolox (2-carboxy-2.5.7.8-tetraamethyl-6-chromanol). another amphipathic reductant, also stimulated root growth, while other hydrophilic reductants including ascorbate. NADPH, NADH and glutathione did not. Some surfactants promoted root growth but their stimulating effects were smaller than the optimum effect of CSI. These results suggest a possible Function of CSI as an amphipathic reductant in root growth regulation.     

Antigen structural requirements for recognition by a cyclobutane thymine dimer-specific monoclonal antibody.

A monoclonal antibody (TDM-2) specific to a UV-induced cyclobutane pyrimidine dimer (T[cis-syn]T) has previously been established; however,the immunization had used UV-irradiated calf-thymus DNA containing a heterogeneous mixture of photoproduct sites. We investigated here the structural requirements of antigen recognition by the antibody using chemically synthesized antigen analogs. TDM-2 bound with cis-syn,but not trans-syn thymine dimer,and could bind strongly with four nucleotide analogs in which the cis-syn pyrimidine dimer was located in the center. Antigen analogs containing abasic linkers at the 5'- or 3'-side of the cis-syn cyclobutane pyrimidine dimer were synthesized and tested for binding to TDM-2. The results indicated that TDM-2 recognizes not only the cyclobutane ring but also both the 5'- and 3'-side nucleosides of the cyclobutane dimer. Furthermore,it was proved that either the 5'- or 3'-side phosphate group at a cyclobutane dimer site was absolutely required for the affinity to TDM-2. The antibody showed a strong binding to single stranded DNA but indicated little binding to double stranded DNA.     

Amplification of epidermal growth factor receptor (EGFR) gene and oncogenes in human gastric carcinomas

DNAs from 37 human gastric carcinomas and seven lymph node metastases were analyzed for alterations of the epidermal growth factor receptor (EGFR) gene and oncogenes by the Southern blot hybridization method. The probes used were EGFR gene, c-Ha-ras, v-Ki-ras, N-ras, c-myc, v-myb, v-fos, c-erbB-2, v-erbA, v-abl and v-fes. Amplification of the EGFR gene was detected in only one poorly differentiated adenocarcinoma. Amplifications of c-myc gene and c-erbB-2 gene were each observed in two well differentiated adenocarcinomas. One of these tumors had coamplification of c-erbB-2 and c-erbA genes but there were no amplifications nor rearrangements of other oncogenes. The poorly differentiated adenocarcinom with amplified EGFR gene also showed enhanced expression of EGFR gene by Northern blot analysis and additionally had strong synchronous immunoreactivity for EGFR and EGF.     

DNA ploidy pattern and amplification of ERBB and ERBB2 genes in human gastric carcinomas

The DNA ploidy pattern and amplification of ERBB and ERBB2 genes were examined in paraffinembedded tissue from gastric carcinomas using flow cytometry and a slot-blot hybridization technique. The incidence of aneuploidy in well differentiated adenocarcinomas (56%) was significantly higher (p<0.05) than that in poorly differentiated adenocarcinomas (21%). The DNA ploidy pattern was not remarkably different between the primary tumors and metastatic deposits in lymph nodes. Of the nine specimens having an aneuploid stem cell line in the primary tumor and/or in metastases, three showed ERBB2 gene amplification and one showed ERBB gene amplification. The incidence of epidermal growth factor (EGF) immunoreactivity in tumor cells showed no difference between diploid and aneuploid tumors. These findings indicate that aneuploidy is frequently associated with amplification of ERBB and ERBB2 genes.     

Amino acid sequences of cytotoxin-like basic proteins derived from cobra venoms

Amino acid sequences of cytotoxin-like basic proteins (CLBPs), purified from the venoms of Formosan cobra (Naja naja atra) and Indian cobra (Naja naja), were reinvestigated. The determined sequences differed from those reported previously by Takechi et al. [(1985) Biochem. Int. 11, 795-802; (1987) Biochem. Int. 14, 145-152]. The sequence of CLBPs at residues 25-30 was found to be hydrophilic as compared with those of cytotoxins. The difference in the hydrophobicity of this region might be responsible for the difference in their cytotoxic activities.     

Synthesis of 5'-phosphatidylnucleosides by phospholipase D-catalyzed transphosphatidylation

Phospholipase D from Streptomyces effectively catalyzed the transfer reaction of the phosphatidyl residue from phosphatidylcholine to the 5'-hydroxyl group of nucleosides. A variety of 5'-phosphatidylnucleosides were prepared by this reaction in high yields. Some of them showed marked antitumor activities in mice.     

Oxidative stress provokes atherogenic changes in adipokine gene expression in 3T3-L1 adipocytes

Increased oxidative stress has been associated with obesity-related disorders. In this study, we investigated how oxidative stress, in different ways of exposure, regulates gene expression of various adipokines in 3T3-L1 adipocytes. Exposure to 100-500microM H(2)O(2) for 10min, as well as exposure to 5-25mU/ml glucose oxidase for 18h, similarly decreased adiponectin, leptin, and resistin mRNAs, and increased plasminogen activator inhibitor-1 mRNA. Secretion levels of adipokines were also changed by oxidative stress in parallel with mRNA expression levels. Although a peak increase in plasminogen activator inhibitor-1 mRNA was achieved between 4 and 8h after exposure to H(2)O(2) for 10min, significant decreases in adiponectin and resistin mRNA were observed after 16h, while leptin mRNA was decreased earlier. Our results suggest that oxidative stress, even of short duration, has a significant impact on the regulation of various adipokine gene expressions favoring atherosclerosis.     

Optimization of a series of 2,4-diaminopyridines as neuropeptide Y Y1 receptor antagonists with reduced hERG activity

The synthesis and evaluation of a series of 2,4-diaminopyridine-based neuropeptide Y Y1 (NPY Y1) receptor antagonists are described. Compound 1 was previously reported by our laboratory to be a potent and selective Y1 antagonist; however, 1 was also found to have potent hERG inhibitory activity. The main focus of this communication is structure–activity relationship development aimed at eliminating the hERG activity of 1. This resulted in the identification of compound 3d as a potent and selective NPY Y1 antagonist with reduced hERG liability.     

Critical role of neuropeptides B/W receptor 1 signaling in social behavior and fear memory

Neuropeptide B/W receptor 1 (NPBWR1) is a G-protein coupled receptor, which was initially reported as an orphan receptor, and whose ligands were identified by this and other groups in 2002 and 2003. To examine the physiological roles of NPBWR1, we examined phenotype of Npbwr1 ^−/− mice. When presented with an intruder mouse, Npbwr1 ^−/− mice showed impulsive contact with the strange mice, produced more intense approaches toward them, and had longer contact and chasing time along with greater and sustained elevation of heart rate and blood pressure compared to wild type mice. Npbwr1 ^−/− mice also showed increased autonomic and neuroendocrine responses to physical stress, suggesting that impairment of NPBWR1 leads to stress vulnerability. We also observed that these mice show abnormality in the contextual fear conditioning test. These data suggest that NPBWR1 plays a critical role in limbic system function and stress responses. Histological and electrophysiological studies showed that NPBWR1 acts as an inhibitory regulator on a subpopulation of GABAergic neurons in the lateral division of the CeA and terminates stress responses. These findings suggest important roles of NPBWR1 in regulating amygdala function during physical and social stress.