Design, synthesis, and biological evaluation of tricyclic heterocycle-tetraamine conjugates as potent NMDA channel blockers

We have developed a new class of N-methyl-d-aspartate (NMDA) channel blockers having a conjugate structure that consists of a nitrogenous heterocyclic head and a tetraamine tail. Among them, dihydrodibenzazepine-homospermine conjugate (8) exhibited potent antagonistic activity at NR1/NR2A or NR1/NR2B NMDA subtype receptors compared with the lead compound, AQ343 (1), or memantine, as well as weak cytotoxicity. Its superior biological profiles compared with known compounds point to its potential use as therapeutic agents for neurological disorders.     

Biosynthesis of Firefly Luciferin in Adult Lantern: Decarboxylation of ?-Cysteine is a Key Step for Benzothiazole Ring Formation in Firefly Luciferin Synthesis

Background

Bioluminescence in fireflies and click beetles is produced by a luciferase-luciferin reaction. The luminescence property and protein structure of firefly luciferase have been investigated, and its cDNA has been used for various assay systems. The chemical structure of firefly luciferin was identified as the ᴅ-form in 1963 and studies on the biosynthesis of firefly luciferin began early in the 1970’s. Incorporation experiments using ¹⁴C-labeled compounds were performed, and cysteine and benzoquinone/hydroquinone were proposed to be biosynthetic component for firefly luciferin. However, there have been no clear conclusions regarding the biosynthetic components of firefly luciferin over 30 years.

Methodology/Principal Findings

Incorporation studies were performed by injecting stable isotope-labeled compounds, including ʟ-[U-¹³C₃]-cysteine, ʟ-[1-¹³C]-cysteine, ʟ-[3-¹³C]-cysteine, 1,4-[D₆]-hydroquinone, and p-[2,3,5,6-D]-benzoquinone, into the adult lantern of the living Japanese firefly Luciola lateralis. After extracting firefly luciferin from the lantern, the incorporation of stable isotope-labeled compounds into firefly luciferin was identified by LC/ESI-TOF-MS. The positions of the stable isotope atoms in firefly luciferin were determined by the mass fragmentation of firefly luciferin.

Conclusions

We demonstrated for the first time that ᴅ- and ʟ-firefly luciferins are biosynthesized in the lantern of the adult firefly from two ʟ-cysteine molecules with p-benzoquinone/1,4-hydroquinone, accompanied by the decarboxylation of ʟ-cysteine.     

Structural Analysis of Sydowic Acid by X-ray Diffraction

Streptomyces sp. No. 280 produced several kinds of amylase inhibitors (amylase inhibitor A, B, B' and C). Two amylase inhibitors (designated as AI-A₁ and AI-A₂) were obtained from an amylase inhibitor A fraction by paper chromatography. AI-A₁ inhibited muscle phosphorylase a much more than AI-A₂ and was hydrolyzed by sweet potato β-amylase whereas AI-A₂ was not. Both amylase inhibitors had a carbohydrate and were hydrolyzed by some kinds of amylases or acids. They lost their inhibitory activity against phosphorylase a after treatment with acids or hog pancreatic α-amylase, but they showed increased inhibitory activity toward porcine small intestinal sucrase.

Both AI-A₁ and AI-A₂ were composed of glucose and a basic moiety which gave a positive ninhydrin reaction. The molecular weights of AI-A₁ and AI-A₂ were estimated to be approximately 1300 ? 1500 by gel filtration on a Sephadex G-15 column. The nitrogen content of the amylase inhibitors was found to be about 1.3% by elementary analysis     

Skeletal FGFR1 signaling is necessary for regulation of serum phosphate level by FGF23 and normal life span

Fibroblast growth factor (FGF) 23 produced by the bone is the principal hormone to regulate serum phosphate level. Serum FGF23 needs to be tightly regulated to maintain serum phosphate in a narrow range. Thus, we hypothesized that the bone has some phosphate-sensing mechanism to regulate the production of FGF23. Previously we showed that extracellular phosphate induces the phosphorylation of FGF receptor 1 (FGFR1) and FGFR1 signaling regulates the expression of Galnt3, whose product works to increase FGF23 production in vitro. In this study, we show the significance of FGFR1 in the regulated FGF23 production and serum phosphate level in vivo. We generated late-osteoblast/osteocyte-specific Fgfr1-knockout mice (Fgfr1^fl/fl; Ocn^Cre/+) by crossing the Ocn-Cre and the floxed Fgfr1 mouse lines. We evaluated serum phosphate and FGF23 levels, the expression of Galnt3 in the bone, the body weight and life span. A selective ablation of Fgfr1 aborted the increase of serum active full-length FGF23 and the enhanced expression of Galnt3 in the bone by a high phosphate diet. These mice showed more pronounced hyperphosphatemia compared with control mice. In addition, these mice fed with a control diet showed body weight loss after 23 weeks of age and shorter life span. These results reveal a novel significance of FGFR1 signaling in the phosphate metabolism and normal life span.     

Accelerating Effect of Soy Peptides Containing Collagen Peptides on Type I and III Collagen Levels in Rat Skin

Two weeks of feeding soy peptides containing 2% collagen peptides increased the levels of type I and III tropocollagen and their mRNAs. In contrast, the diet did not increase the mRNA levels of rat hyaluronan synthases, serine palmitoyltransferase (the rate-limiting enzyme of ceramide synthesis), and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (the key enzyme of cholesterol synthesis). These results suggest that feeding of soy peptides with collagen peptides specifically enhanced the tropocollagen level in the skin.     

Can Experience Improve Hospital Management?

Background

Experience curve effects were first observed in the industrial arena as demonstrations of the relationship between experience and efficiency. These relationships were largely determined by improvements in management efficiency and quality of care. In the health care industry, volume-outcome relationships have been established with respect to quality of care improvement, but little is known about the effects of experience on management efficiency. Here, we examine the relationship between experience and hospital management in Japanese hospitals.

Methods

The study sample comprised individuals who had undergone surgery for unruptured abdominal aortic aneurysms and had been discharged from participant hospitals between April 1, 2006 and December 31, 2008. We analyzed the association between case volume (both at the hospital and surgeon level) and postoperative complications using multilevel logistic regression analysis. Multilevel log-linear regression analyses were performed to investigate the associations between case volume and length of stay (LOS) before and after surgery.

Results

We analyzed 909 patients and 849 patients using the hospital-level and surgeon-level analytical models, respectively. The odds ratio of postoperative complication occurrence for an increase of one surgery annually was 0.981 (P<0.001) at the hospital level and 0.982 (P<0.001) at the surgeon level. The log-linear regression analyses showed that shorter postoperative LOS was significantly associated with high hospital-level case volume (coefficient for an increase of one surgery: −0.006, P = 0.009) and surgeon-level case volume (coefficient for an increase of one surgery: −0.011, P = 0.022). Although an increase of one surgery annually at the hospital level was statistically associated with a reduction of preoperative LOS by 1.1% (P = 0.006), there was no significant association detected between surgeon-level case volume and preoperative LOS (P = 0.504).

Conclusion

Experience at the hospital level may contribute to the improvement of hospital management efficiency.     

The inhibitory effects of mushroom extracts on sucrose-dependent oral biofilm formation

Mushrooms contain large quantities of α-glucans. Shiitake (Lentinula edodes), Japan’s most popular edible mushroom, has been reported to contain about 6% (weight/dried weight) of α-(1,3)-glucan. This glucan is one of the major components of oral biofilm formed by the cariogenic bacteria Streptococcus mutans and Streptococcus sobrinus. We found that extracts from shiitake and other edible mushrooms could reduce preformed biofilms of S. mutans and S. sobrinus in the presence of dextranase. We also investigated the α-glucanase activities of shiitake mushroom extracts and their effects on biofilm formation. The extracts possessed α-glucanase activity and degraded water-insoluble glucans from mutans streptococci. The extracts strongly inhibited the sucrose-dependent formation of biofilms by S. mutans and S. sobrinus in the presence of dextranase. Our results suggest that some components of mushrooms, including α-glucanases, might inhibit the sucrose-induced formation of oral biofilms.     

Hepatitis C Virus Impairs p53 via Persistent Overexpression of 3��-Hydroxysterol ��24-Reductase

Persistent infection with hepatitis C virus (HCV) induces tumorigenicity in hepatocytes. To gain insight into the mechanisms underlying this process, we generated monoclonal antibodies on a genome-wide scale against an HCV-expressing human hepatoblastoma-derived cell line, RzM6-LC, showing augmented tumorigenicity. We identified 3β-hydroxysterol Δ24-reductase (DHCR24) from this screen and showed that its expression reflected tumorigenicity. HCV induced the DHCR24 overexpression in human hepatocytes. Ectopic or HCV-induced DHCR24 overexpression resulted in resistance to oxidative stress-induced apoptosis and suppressed p53 activity. DHCR24 overexpression in these cells paralleled the increased interaction between p53 and MDM2 (also known as HDM2), a p53-specific E3 ubiquitin ligase, in the cytoplasm. Persistent DHCR24 overexpression did not alter the phosphorylation status of p53 but resulted in decreased acetylation of p53 at lysine residues 373 and 382 in the nucleus after treatment with hydrogen peroxide. Taken together, these results suggest that DHCR24 is elevated in response to HCV infection and inhibits the p53 stress response by stimulating the accumulation of the MDM2-p53 complex in the cytoplasm and by inhibiting the acetylation of p53 in the nucleus.