Promotion of radiation-induced formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine by nitro 5-deazaflavin derivatives.

6-Nitro- and 8-nitro-5-deazaflavin derivatives have been found to enhance prominently the radiation-induced formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) at the expense of formation of 2,6-diamino-4-hydroxy-5-formamidopyrimidine nucleosides (FapydGuo) both in deaerated and in N(2)O saturated aqueous 2'-deoxyguanosine solutions. The radiosensitizing capacity of a 9-nitro-5-deazflavin derivative was observed only in the N(2)O saturated aqueous solutions.     

Anatomy of the frontal branch of the facial nerve: the significance of the temporal fat pad

The anatomy of the temporal region, with reference to the frontal branch of the facial nerve, was examined in 12 fresh cadaver dissections. In all dissections, the frontal branch traveled in a constant plane along the undersurface of the temporoparietal fascia and was quite superficial as it crossed the zygomatic arch. The deep temporal fascia and superficial temporal fat pad are anatomically important structures which adjoin the periosteum of the zygomatic arch and lie deep to the frontal nerve. Based on these relationships, a safe method of dissection within the temporal region is formulated.     

Molecular and functional analysis of the ribosomal L11 and S12 protein genes ( rplK and rpsL ) of Streptomyces coelicolor A3(2)

A RelC deletion mutant, KO-100, of Streptomyces coelicolor A3(2) has been isolated from a collection of spontaneous thiostrepton-resistant mutants. KO-100 grows as vigorously as the parent strain and possesses a 6-bp deletion within the rplK, previously termed relC. When the wild-type rplK gene was propagated on a low-copy-number vector in mutant KO-100, the ability to produce ppGpp, actinorhodin and undecylprodigiosin, which had been lost in the RelC mutant, was completely restored. Allele replacement by gene homogenotization demonstrated that the RelC mutation is responsible for the resistance to thiostrepton and the inactivation of ppGpp, actinorhodin and undecylprodigiosin production. Western blotting showed that ribosomes from the RelC mutant KO-100 contain only one-eighth the amount of L11 protein found in ribosomes of the parent strain. The impairment of antibiotic production in KO-100 could be rescued by the introduction of mutations that confer resistance to streptomycin (str), which result in alteration of Lys-88 in ribosomal protein S12 to Glu or Arg. No accompanying restoration of ppGpp synthesis was detected in these RelC str double mutants. Received: 12 May 1997 / Accepted: 22 July 1997     

Carotid thrombosis following surgical release of temporomandibular ankylosis

Temporomandibular ankylosis frequently involves massive bony proliferation which can approach the carotid artery at the base of the skull. During the resection of the bony ankylosis, the artery can be injured. The first such case is reported which led to a thrombosis and hemispheric stroke.     

An approach to the mechanism of the asymmetrical radical formation in yttrium-90-beta-irradiated D- and L-alanines

Several attempts were made to investigate the mechanism of the asymmetrical radical formation in yttrium-90-beta-irradiated D- and L-alanines which was reported in the preceding paper (1). The experiments demonstrated that the magnitude of the asymmetry was dependent on beta-ray dose, namely the lower the dose the larger the observed difference was, and that no difference could be detected when the alanines were irradiated in aqueous state. The results in the present study seem to that different interaction between the crystal structure of the two enantiomers and polarized beta-rays may be responsible for the observed phenomenon.     

Discovery of orally efficacious RORγt inverse agonists. Part 2: Design,synthesis, and biological evaluation of novel tetrahydroisoquinoline derivatives

A series of tetrahydroisoquinoline derivatives were designed, synthesized, and evaluated for their potential as novel orally efficacious retinoic acid receptor-related orphan receptor-gamma t (RORγt) inverse agonists for the treatment of Th17-driven autoimmune diseases. We carried out cyclization of the phenylglycinamide core by structure-based drug design and successfully identified a tetrahydroisoquinoline carboxylic acid derivative 14 with good biochemical binding and cellular reporter activity. Interestingly, the combination of a carboxylic acid tether and a central fused bicyclic ring was crucial for optimizing PK properties, and the compound 14 showed significantly improved PK profile. Successive optimization of the carboxylate tether led to the discovery of compound 15 with increased inverse agonistic activity and an excellent PK profile. Oral treatment of mice with compound 15 robustly and dose-dependently inhibited IL-17A production in an IL23-induced gene expression assay.     

Glyoxal and methylglyoxal trigger distinct signals for map family kinases and caspase activation in human endothelial cells.

Carbonyl compounds with diverse carbon skeletons may be differentially related to the pathogenesis of vascular diseases. In this study, we compared intracellular signals delivered into cultured human umbilical vein endothelial cells (HUVECs) by glyoxal (GO) and methylglyoxal (MGO), which differ only by a methyl group. Depending on their concentrations, GO and MGO promoted phosphorylations of ERK1 and ERK2, which were blocked by the protein-tyrosine kinase (PTK) inhibitors herbimycin A and staurosporine, thereby being PTK-dependent. GO and MGO also induced phosphorylations of JNK, p38 MAPK, and c-Jun, either PTK-dependently (GO) or -independently (MGO). Next, we found that MGO, but not GO, induced degradation of poly(ADP-ribose) polymerase (PARP) as the intracellular substrate of caspase-3. Curcumin and SB203580, which inhibit JNK and p38 MAPK signaling pathways, but not herbimycin A/staurosporine, prevented the MGO-induced PARP degradation. We then found that MGO, but not GO, reduced the intracellular glutathione level, and that cysteine, but not cystine, inhibited the MGO-mediated activation of ERK, JNK, p38 MAPK, or c-Jun more extensively than did lysine or arginine. In addition, all the signals triggered by GO and MGO were blocked by amino guanidine (AG), which traps carbonyls. These results demonstrated that GO and MGO triggered two distinct signal cascades, one for PTK-dependent control of ERK and another for PTK-independent redox-linked activation of JNK/p38 MAPK and caspases in HUVECs, depending on the structure of the carbon skeleton of the chemicals.     

Synthesis of homoursodeoxycholic acid and [11,12-3H]homoursodeoxycholic acid

Homoursodeoxycholic acid and [11,12-³H]homoursodeoxycholic acid were synthesized from ursodeoxycholic acid and homocholic acid, respectively. Ursodeoxycholic acid (Ia) was converted to 3α,7β-diformoxy-5β-cholan-24-oic acid (Ib) using formic acid. Reaction of the diformoxy derivative (Ib) with thionyl chloride yielded the acid chloride (II) which was treated with diazomethane to produce 3α,7β-diformoxy-25-diazo-25-homo-5β-cholan-24-one (III). Homoursodeoxycholic acid (IV) was formed from the diazoketone (III) by means of the Wolff rearrangement of the Arndt-Eistert synthesis.N-Bromosuccinimide oxidation of homocholic acid (V), which was prepared from cholic acid by the same procedure described above, afforded 3α,12α-dihydroxy-7-oxo-25-homo-5β-cholan-25-oic acid (VI). Reduction of the 7-ketohomodeoxycholic acid (VI) with sodium in 1-propanol gave 3α,7β,12α-trihydroxy-25-homo-5β-cholan-25-oic acid (VII). The methyl ester of 7-epihomocholic acid (VII) was partially acetylated to give methyl 3α,7β-diacetoxy-12α-hydroxy-25-homo-5β-cholan-25-oate (VIII) using a mixture of acetic anhydride, pyridine and benzene. Dehydration of the diacetoxy derivative (VIII) with phosphorus oxychloride yielded methyl 3α,7β-diacetoxy-25-homo-5β-chol-11-en-25-oate (IX). Reduction of the unsaturated ester (IX) with tritium gas in the presence of platinum oxide catalyst followed by alkaline hydrolysis gave [11,12-³H]homoursodeoxycholic acid.