Synthesis of a carbon analogue of scytonemin

The synthesis of a carbon analogue of scytonemin was accomplished on the basis of molybdenum-mediated intramolecular double Pauson-Khand type reaction of bis(allenyne), followed by the double aldol condensation of the formed double Pauson-Khand type adduct.

Synthesis of planar chiral [2.2]paracyclophane-based bisoxazoline ligands bearing no central chirality and application to Cu-catalyzed asymmetric O–H insertion reaction

C ₂-symmetric planar chiral [2.2]paracyclophane-based bisoxazoline ligands effectively control the asymmetric induction during the Cu-catalyzed O–H insertion reaction of α-diazo esters.

Air-stable cationic gold(I) catalyst featuring a Z-type ligand: promoting enyne cyclizations

An air-stable cationic Au(I) complex featuring a Z-type ligand (boron atom) as a σ-acceptor was developed for elucidating the effect of B on catalytic reactions. An enyne cyclization in the presence of either [Au→B](+) or [Au](+) showed that [Au→B](+) promotes the reactivity, which enabled the effective construction of not only five- and six-membered rings, but also seven-membered rings.

Non-randomized controlled prospective study on perioperative levels of stress and dysautonomia during dental implant surgery

PURPOSE

The purpose of this study was to compare pre- and postoperative autonomic activities and changes in salivary stress biomarkers between patients who received only local anesthesia and those who received local anesthesia together with intravenous sedation in dental implant surgery.

METHODS

A total of 21 patients were enrolled in this non-randomized controlled prospective study; 7 subjects underwent implant surgery under local anesthesia with intravenous sedation and 14 subjects underwent surgery under only local anesthesia. Stress was evaluated by measuring salivary levels of chromogranin A (CgA) and a spectral analysis of heart rate variability (HRV) at baseline (on a day other than the day of surgery), 1h preoperatively, and 1h postoperatively. HRV analysis yields low- (LF) and high-frequency (HF) components, the LF/HF ratio, and the component coefficient of variance (CCV[HF]), which provide indices of sympathetic and parasympathetic regulatory activity.

RESULTS

CgA levels were significantly higher (p<0.05) at baseline in patients who received sedation than those who did not, but CgA levels did not differ prior to surgery. Also, the values of most parameters, including LF, HF, LF/HF (L/H), and CCV(HF), did not significantly differ between groups or among the three time points. Only ΔL/H and ΔCCV(HF) were significantly lower (p<0.05) at 1h preoperatively in patients who received sedation than those who received only local anesthesia.

CONCLUSIONS

CgA levels were high in both groups immediately before surgery, and thus CgA values immediately before surgery may not be a reliable indicator of the need for intravenous sedation. Also, spectral analysis of HRV, especially ΔL/H and ΔCCV(HF), could be useful for assessing tension and anxiety.

Histidine augments the suppression of hepatic glucose production by central insulin action

Glucose intolerance in type 2 diabetes is related to enhanced hepatic glucose production (HGP) due to the increased expression of hepatic gluconeogenic enzymes. Previously, we revealed that hepatic STAT3 decreases the expression of hepatic gluconeogenic enzymes and suppresses HGP. Here, we show that increased plasma histidine results in hepatic STAT3 activation. Intravenous and intracerebroventricular (ICV) administration of histidine-activated hepatic STAT3 reduced G6Pase protein and mRNA levels and augmented HGP suppression by insulin. This suppression of hepatic gluconeogenesis by histidine was abolished by hepatic STAT3 deficiency or hepatic Kupffer cell depletion. Inhibition of HGP by histidine was also blocked by ICV administration of a histamine H1 receptor antagonist. Therefore, histidine activates hepatic STAT3 and suppresses HGP via central histamine action. Hepatic STAT3 phosphorylation after histidine ICV administration was attenuated in histamine H1 receptor knockout (Hrh1KO) mice but not in neuron-specific insulin receptor knockout (NIRKO) mice. Conversely, hepatic STAT3 phosphorylation after insulin ICV administration was attenuated in NIRKO but not in Hrh1KO mice. These findings suggest that central histidine action is independent of central insulin action, while both have additive effects on HGP suppression. Our results indicate that central histidine/histamine-mediated suppression of HGP is a potential target for the treatment of type 2 diabetes.

What sperm can teach us about energy production

Mammalian sperm have evolved under strict selection pressures that have resulted in a highly polarized and efficient design. A critical component of that design is the compartmentalization of specific metabolic pathways to specific regions of the cell. Although the restricted localization of mitochondria to the midpiece is the best known example of this design, the organization of the enzymes of glycolysis along the fibrous sheath is the primary focus of this review. Evolution of variants of these metabolic enzymes has allowed them to function when tethered, enabling localized energy production that is essential for sperm motility. We close by exploring how this design might be mimicked to provide an energy-producing platform technology for applications in nanobiotechnology.