Cyclic amine sulfonamides as linkers in the design and synthesis of novel human beta(3) adrenergic receptor agonists

Piperidine, pyrrolidine, and azetidine sulfonamides were examined as linkers in designing novel human beta(3) adrenergic receptor (beta(3)-AR) agonists. The azetidine derivative 37, and piperidine derivatives 7, 8, and 13 were found to be potent beta(3)-AR agonists and have good selectivity against beta(1)- and beta(2)-AR.     

Expression of epidermal growth factor in salivary adenoid cystic carcinoma

This study used an immunohistochemical technique to assess the expression of epidermal growth factor (EGF) in 40 specimens of salivary adenoid cystic carcinoma (ACC), 7 specimens of labial glands adjacent to mucocele, and 5 specimens of normal submandibular glands. In normal submandibular glands, immunohistochemically detectable EGF was demonstrated in all ductal segments, including intercalated, striated, and excretory duct cells. No EGF positive staining was found in acinar compartments. including serous and mucous acinar cells. In degenerated labial glands adjacent to mucocele, no EGF staining was detected in the remaining acinar and ductal cells. In salivary ACCs, positive EGF immunostaining was observed in one of the 5 (20%) ACCs with a solid pattern and in 13 of the 35 (37.1%) ACCs with a tubular-cribriform pattern. The overall EGF expression rate in 40 salivary ACCs was 35%. Positive EGF staining was predominantly found in tubular structures in the tubular ACCs and in duct-like structures in large cribriform patterns or in the stroma of the cribriform ACCs. There was no significant correlation between EGF expression in salivary ACCs and any of the clinicopathological parameters including patient age and sex, cancer location, TNM status, clinical stage, histologic type, perivascular or perineural invasion, focal necrosis of tumor, and cellular atypia. We conclude that the duct segments of the normal submandibular gland are the sites of EGF synthesis and secretion. In degenerated labial glands adjacent to mucocele, EGF synthesis is completely inhibited. Furthermore, EGF is mainly biosynthesized in cells forming tubular or duct-like structures in tubular or cribriform salivary ACCs, and EGF may play a biologic role, particularly as a mitogen in salivary ACC growth.     

Characterization of nucleoside transport systems in cultured rat epididymal epithelium

The nucleoside transport systems in cultured epididymal epithelium were characterized and found to be similar between the proximal (caput and corpus) and distal (cauda) regions of the epididymis. Functional studies revealed that 70% of the total nucleoside uptake was Na(+) dependent, while 30% was Na(+) independent. The Na(+)-independent nucleoside transport was mediated by both the equilibrative nitrobenzylthioinosine (NBMPR)-sensitive system (40%) and the NBMPR-insensitive system (60%), which was supported by a biphasic dose response to NBMPR inhibition. The Na(+)-dependent [(3)H]uridine uptake was selectively inhibited 80% by purine nucleosides, indicating that the purine nucleoside-selective N1 system is predominant. Since Na(+)-dependent [(3)H]guanosine uptake was inhibited by thymidine by 20% and Na(+)-dependent [(3)H]thymidine uptake was broadly inhibited by purine and pyrimidine nucleosides, this suggested the presence of the broadly selective N3 system accounting for 20% of Na(+)-dependent nucleoside uptake. Results of RT-PCR confirmed the presence of mRNA for equilibrative nucleoside transporter (ENT) 1, ENT2, and concentrative nucleoside transporter (CNT) 2 and the absence of CNT1. It is suggested that the nucleoside transporters in epididymis may be important for sperm maturation by regulating the extracellular concentration of adenosine in epididymal plasma.     

Enhanced activity of adenine-DNA glycosylase (Myh) by apurinic/apyrimidinic endonuclease (Ape1) in mammalian base excision repair of an A/GO mismatch

Adenine-DNA glycosylase MutY of Escherichia coli catalyzes the cleavage of adenine when mismatched with 7,8-dihydro-8-oxoguanine (GO), an oxidatively damaged base. The biological outcome is the prevention of C/G→A/T transversions. The molecular mechanism of base excision repair (BER) of A/GO in mammals is not well understood. In this study we report stimulation of mammalian adenine-DNA glycosylase activity by apurinic/apyrimidinic (AP) endonuclease using murine homolog of MutY (Myh) and human AP endonuclease (Ape1), which shares 94% amino acid identity with its murine homolog Apex. After removal of adenine by the Myh glycosylase activity, intact AP DNA remains due to lack of an efficient Myh AP lyase activity. The study of wild-type Ape1 and its catalytic mutant H309N demonstrates that Ape1 catalytic activity is required for formation of cleaved AP DNA. It also appears that Ape1 stimulates Myh glycosylase activity by increasing formation of the Myh–DNA complex. This stimulation is independent of the catalytic activity of Ape1. Consequently, Ape1 preserves the Myh preference for A/GO over A/G and improves overall glycosylase efficiency. Our study suggests that protein–protein interactions may occur in vivo to achieve efficient BER of A/GO.     

Human scFv antibody fragments specific for the epithelial tumour marker MUC-1, selected by phage display on living cells

New anti-cancer agents are being developed that specifically recognise tumour cells. Recognition is dependent upon the enhanced expression of antigenic determinants on the surface of tumour cells. The tumour exposure and the extracellular accessibility of the mucin MUC-1 make this marker a suitable target for tumour diagnosis and therapy. We isolated and characterised six human scFv antibody fragments that bound to the MUC-1 core protein, by selecting a large naive human phage display library directly on a MUC-1-expressing breast carcinoma cell line. Their binding characteristics have been studied by ELISA, FACS and indirect immunofluorescence. The human scFv antibody fragments were specific for the tandem repeat region of MUC-1 and their binding is inhibited by soluble antigen. Four human scFv antibody fragments (M2, M3, M8, M12) recognised the hydrophilic PDTRP region of the MUC-1 core protein, which is thought to be an immunodominant region. The human scFv antibody fragments were stable in human serum at 37 °C and retained their binding specificity. For imaging or targeting to tumours over-expressing MUC-1, it might be feasible to use these human scFv, or multivalent derivatives, as vehicles to deliver anti-cancer agents. Received: 2 November 2000 / Accepted: 11 January 2001     

Kappa- but not delta-opioid receptors mediate effects of ischemic preconditioning on both infarct and arrhythmia in rats

Two series of experiments were performed in the isolated perfused rat heart to determine the role of kappa- and delta-opioid receptors (OR) in cardioprotection of ischemic preconditioning (IP). In the first series of experiments, it was found that IP with two cycles of 5-min regional ischemia followed by 5-min reperfusion each reduced infarct size induced by 30-min ischemia, and the ameliorating effect of IP on infarct was attenuated with blockade of either 5 x 10(-6) mol/l nor-binaltorphimine (nor-BNI), a selective kappa-OR antagonist, or 5 x 10(-6) mol/l naltrindole (NTD), a selective delta-OR antagonist. The second series showed that U50,488H, a selective kappa-OR agonist, or D-Ala(2)-D-leu(5)-enkephalin (DADLE), a selective delta-OR agonist, dose dependently reduced the infarct size induced by ischemia, which mimicked the effects of IP. The effect of 10(-5) mol/l U50,488H on infarct was significantly attenuated by blockade of protein kinase C (PKC) with specific PKC inhibitors, 5 x 10(-6) mol/l chelerythrine or 8 x 10(-7) mol/l calphostin C, as well as by blockade of ATP-sensitive K(+) (K(ATP)) channels with blockers of the channel, 10(-5) mol/l glibenclamide or 10(-4) mol/l 5-hydroxydecanoate. IP also reduced arrhythmia induced by ischemia. Nor-BNI, but not NTD, attenuated, while U50,488H, but not DADLE, mimicked the antiarrhythmic action of IP. In conclusion, the present study has provided first evidence that kappa-OR mediates the ameliorating effects of IP on infarct and arrhythmia induced by ischemia, whereas delta-OR mediates the effects only on infarct. Both PKC and K(ATP) channels mediate the effect of activation of kappa-OR on infarct.     

Establishment and characterization of a cell line (HCDB-1) derived from a hamster buccal pouch carcinoma induced by DMBA and Taiwanese betel quid extract

This study identified that the carcinogenesis of hamster buccal pouch (HBP) induced by 7,12-dimethylbenz[a]anthracene (DMBA) was greatly enhanced (18 folds) by a combination treatment with Taiwanese betel quid (BQ) extract. A new cell line, HCDB-1, has been established from induced carcinomas. The cultured monolayer cells were epithelioid in shape with irregular nuclei. They demonstrated abundant cytokeratin and tonofilaments; however, ultrastructural well-organized desmosomes were lacking. The HCDB-1 cell exhibited population doubling in 19 h and was highly tumorigenic in nude mice. A C-->T transition at codon 141 (Ala to Val) of the p53 gene was detected in this cell. This mutation is equivalent to a specific temperature-sensitive mouse p53Ala135Val mutant that causes transformation by shifting to 37.5 degrees C. HCDB-1 is the first cell line established from the HBP model of oral carcinogenesis induced by DMBA/Taiwanese BQ extract. It might be valuable for exploring the molecular pathogenesis of oral cancer.     

Evidence for transduction of mu but not kappa opioid modulation of extracellular signal-regulated kinase activity by G(z) and G(12) proteins

Chronic treatment with micro or kappa opioid agonists (>/=2 h) inhibits EGF-induced ERK activation in opioid receptor overexpressing COS-7 cells. Although acute mu and kappa opioids activate ERK via a pertussis toxin-sensitive G protein, pertussis toxin insensitivity of the chronic mu (but not kappa) action was observed. Here, we tested several pertussis toxin-insensitive G proteins as candidates to transduce acute and/or chronic opioid modulation of ERK. Overexpressed Galpha(z) (but not Galpha(12)) transduced acute mu (but not kappa) ERK activation in pertussis toxin-treated COS-7 cells. Chronic mu (but not kappa) inhibited EGF stimulation of ERK in pertussis toxin-treated cells overexpressing Galpha(z) or Galpha(12). Transfection of Galpha(13) or Galpha(q) blocked inhibition under the same conditions. Overexpressed interfering and non-interfering Galpha(z) mutants differentially affected mu inhibition of ERK consistent with G(z) transduction. In this and prior studies, Galpha(z) and Galpha(12) immunoreactivity were detected in untransfected COS-7 cells, suggesting that these G proteins may be endogenous mediators of chronic mu inhibitory actions on ERK.     

New chiral catalysts for reduction of ketones

The condensation of o-(diphenylphosphino)benzaldehyde and various chiral diamine gives a series of diimino-diphosphine tetradentate ligands, which are reduced with excess NaBH4 in refluxing ethanol to afford the corresponding diaminodiphosphine ligands in good yield. The reactivity of these ligands toward trans-RuCl2(DMSO)4 and [Rh(COD)Cl]2 had been investigated and a number of chiral Ru(II) and Rh(I) complexes with the PNNP-type ligands were synthesized and characterized by microanalysis and IR, NMR spectroscopic methods. The chiral Ru(II) and Rh(I) complexes have proved to be excellent catalyst precursors for the asymmetric transfer hydrogenation of aromatic ketones, leading to optically active alcohols in up to 97% ee.