Search

The polymeric gel electrolytes are attractive owing to their higher ionic conductivities than those of dry polymer electrolytes and lowered water activity for enlarged potential window. However, the ionic conductivity and mechanical strength of the Na‐ion conducting polymeric gel electrolytes are limited by below 20 mS cm−1 and 2.2 MPa. Herein, we demonstrate Na‐ion conducting and flexible polymeric hydrogel electrolytes of the chemically coupled poly(diallyldimethylammonium chloride)‐dextrin‐N,N′‐methylene‐bis‐acrylamide film immersed in NaClO4 solution (ex‐DDA‐Dex + NaClO4) for flexible sodium‐ion hybrid capacitors (f‐NIHC). In particular, the anion exchange reaction and synergistic interaction of ex‐DDA‐Dex with the optimum ClO4− enable to greatly improve the ionic conductivity up to 27.63 mS cm−1 at 25°C and electrochemical stability window up to 2.6 V, whereas the double networking structure leads to achieve both the mechanical strength (7.48 MPa) and softness of hydrogel electrolytes. Therefore, the f‐NIHCs with the ex‐DDA‐Dex + NaClO4 achieved high specific and high‐rate capacities of 192.04 F g−1 at 500 mA g−1 and 116.06 F g−1 at 10 000 mA g−1, respectively, delivering a large energy density of 120.03 W h kg−1 at 906 W kg−1 and long cyclability of 70% over 500 cycles as well as demonstrating functional operation under mechanical stresses. [ABSTRACT FROM AUTHOR]

Microstructural characteristics and wear properties of Fe-16Mn-10Al-5Ni-0.86C lightweight steel (LWS) manufactured by laser powder bed fusion (LPBF) process were investigated and compared with conventional LWS. Both LWS alloys constituted an austenite matrix and B2-IMC. The LPBF LWS sample showed polygonal-typed B2-IMC, whereas conventional LWS had rod-typed B2-IMC. The ball-on-disk method was used to perform a wear test at 25°C under three different load conditions of 20N, 3N and 40N. The wear results indicated that the LPBF LWS sample exhibited a similar amount of wear loss under the 20N and 30N load conditions, but it showed better wear resistance under the 40N compared to conventional LWS. After the wear test, the abrasive wear behaviour was confirmed as the main wear mechanism in both LWSs. The formation of oxide layers and debris was analysed through observation of the cross-sectional area of the worn surface. [ABSTRACT FROM AUTHOR]

ABSTRACT Saururus chinensis (SC) Baill. (Saururaceae), a perennial herb commonly called Chinese lizard's tail or Sambaekcho in Korea, has been used in the treatment of edema, gonorrhea, jaundice, and inflammatory [...]

This study investigates the influence of post‐heat treatment on the microstructure, mechanical properties, and strengthening mechanisms of the IN738LC fabricated via laser powder bed fusion (LPBF). The alloy is subjected to fully hardening (FH) and direct aging (DA) post‐heat treatments, respectively. The supersaturated matrix of the as‐built (AB) IN738LC has a fine cell and columnar structure that is aligned almost parallel to the building direction. After heat treatment, the microstructure of the FH alloy presents a partially recovered matrix. However, the DA alloy indicates a similar matrix structure to that of the AB material. Additionally, bimodal Ni3(Al, Ti) precipitates with average sizes of 176.8 nm in the FH alloy and 112.2 nm in the DA alloy are formed. The ultimate tensile strength (UTS) and elongation at fracture (El.) of AB IN738LC are 1089 MPa and 17%, respectively. The UTS of the DA alloy increases to as much as 1295 MPa and the El. decreases drastically to 3.1%. Analytical calculations for the yield strength prediction were also performed using quantitively measured microstructural parameters. The dominant strengthening contributions for the AB IN738LC are suggested to be the solid solution and dislocation strengthening mechanisms. However, the FH and DA alloys are hardened by solid‐solution and precipitate strengthening. [ABSTRACT FROM AUTHOR]

Additive manufacturing of alloys has gained attention by industry as it provides economical production of complex-configuration engine parts with fewer joining steps and greater geometric freedom. The creep behaviour of additively manufactured (AM) Inconel 625 and 718 at 650 and 800 °C was compared with that of the wrought alloy after 24 hour and long-term tests up to about one year. Inconel 718 is precipitation strengthened while 625 is solid-solution strengthened. It was discovered that the creep strength of the 625 and 718 produced by additively manufacturing is essentially identical than that of the wrought alloy. Complications occur, however, with a marked loss of ductility in the AM alloys. Fatigue and impact toughness were adversely affected as well. The basis for these degradations was particularly investigated. [ABSTRACT FROM AUTHOR]

Ankle sprains are common injuries within the civilian and military populations, with lingering symptoms that include pain, swelling, giving-way, and a high likelihood for recurrence. Numerous bracing systems are available to stabilize the ankle joint following sprains, with new design iterations frequently entering the market. Currently available braces generally include sleeve, lace-up, and stirrup designs. Sleeves provide mild compression and warmth but limited stability for the ankle, while lace-ups and stirrups appear to be more effective at preventing and treating lateral ankle sprains. This review summarizes the use of various brace options in practice. Their major clinical benefits, and limitations are highlighted, followed by an overview of emerging concepts in brace design. Current advancements in biomechanical simulation, multifunctional material fabrication, and wearable, field-deployed devices for human injury surveillance are discussed, providing possibilities for conceiving new design concepts for next-generation smart ankle braces. Performance of the commercially available braces are limited by their current design concepts. Suggestions on future brace design include: (1) incorporating high-performance materials suitable for extreme environments, (2) leveraging modeling and simulation techniques to predict mechanical support requirements, and (3) implementing adaptive, customizable componentry material to meet the needs of each unique patient. [ABSTRACT FROM AUTHOR]

An open‐cell metallic foam is newly manufactured using the electrostatic powder spraying (EPS) process, and its room temperature compressive and energy absorption properties are investigated. EPS is a process that uses electrostatic forces. The powder is negatively charged by applying direct current high voltage and undergoes electrostatic spraying on a positively charged polyurethane pre‐form. To control relative density (ρ*/ρ), three different spray amounts are applied (2.5, 3.5, and 4.5 kg m−2). Also, the relative density is measured to increase constantly with the spray amount. The room temperature compressive curves of the EPS foams represent the typical compressive stages (linear elastic, plastic collapse, and densification) of metallic foam. The plateau strengths of the EPS foams measure 0.48 MPa (spraying amount: 2.5 kg m−2), 0.76 MPa (spraying amount: 3.5 kg m−2), and 1.23 MPa (spraying amount: 4.5 kg m−2), respectively. Also, EPS 316L foam with the smallest spray amount has a lower energy absorption amount compared with other types of foam. This study also discusses the compressive and energy absorption behaviors of an open‐cell metallic foam manufactured using the EPS process in relation to its structural and microstructural characteristics. [ABSTRACT FROM AUTHOR]

Valsartan (VST) is a poorly water-soluble drug and a P-glycoprotein (P-gp) substrate. To enhance the dissolution and oral absorption of VST, a novel supersaturable self-microemulsifying drug delivery system (Su-SMEDDS) was formulated. Based on the previously reported Su-SMEDDS composed of Capmul® MCM (oil), Tween® 20 (T20; surfactant), Transcutol® P (cosurfactant), and Poloxamer 407 (supersaturating agent), P-gp inhibitory surfactants including Tween® 80 (T80) and Cremophor® EL (CR) were newly introduced to replace T20. All Su-SMEDDS formulations had a droplet size of <200 nm and showed rapid (>90% within 5 min) and pH-independent dissolution characteristics. The effective permeability coefficient (Peff) in rat jejunum was obtained using an in situ single-pass intestinal perfusion study: Peff values of Su-SMEDDS-T20, Su-SMEDDS-T80, and Su-SMEDDS-CR were 2.3, 4.1, and 3.4 times greater, respectively, than that of the VST solution. After oral administration of various formulations to rats (equivalent dose of VST 10 mg/kg), plasma drug levels were measured by liquid chromatography-tandem mass spectrometry. The relative bioavailabilities of Su-SMEDDS-T20, Su-SMEDDS-T80, and Su-SMEDDS-CR were 262%, 470%, and 458%, respectively, compared with the VST suspension. Thus, we propose that the Su-SMEDDS-T80 formulation is a good candidate for improving the oral absorption of poorly water-soluble and P-gp substrate drugs such as VST. [ABSTRACT FROM AUTHOR]

To improve the dissolution behavior of telmisartan (TMS), a poorly water-soluble angiotensin II receptor blocker, TMS-phospholipid complex (TPC) was prepared by solvent evaporation method and characterized by differential scanning calorimetry and powder X-ray diffractometry. The crystalline structure of TMS was transited into an amorphous state by TPC formation. The equilibrium solubility of TPC (1.3–6.1 mg/mL) in various vehicles was about 100 times higher than that of TMS (0.009–0.058 mg/mL). TPC-loaded self-microemulsifying drug delivery system (SMEDDS) formulation was optimized using the D-optimal mixture design with the composition of 14% Capryol 90 (oil; X1), 59.9% tween 80 (surfactant; X2), and 26.1% tetraglycol (cosurfactant; X3) as independent variables, which resulted in a droplet size of 22.17 nm (Y1), TMS solubilization of 4.06 mg/mL (Y2), and 99.4% drug release in 15 min (Y3) as response factors. The desirability function value was 0.854, indicating the reliability and accuracy of optimization; in addition, good agreement was found between the model prediction and experimental values of Y1, Y2, and Y3. Dissolution of raw TMS was poor and pH-dependent, where it had extremely low dissolution (< 1% for 2 h) in water, pH 4, and pH 6.8 media; however, it showed fast and high dissolution (> 90% in 5 min) in pH 1.2 medium. In contrast, the dissolution of the optimized TPC-loaded SMEDDS was pH-independent and reached over 90% within 5 min in all the media tested. Thus, we suggested that phospholipid complex formation and SMEDDS formulation using the experimental design method might be a promising approach to enhance the dissolution of poorly soluble drugs. [ABSTRACT FROM AUTHOR]

Abstract: A wideband Wilkinson power divider using parallel LC resonant circuit is proposed for different phase output differences. The design theory of the wideband power divider is derived by making the difference between the slopes of the added line for phase shift and the slopes of parallel LC resonant circuit constant zero, and then, the formula is used to find the value L and C. For easy fabrication, the lumped element L and C are implemented as the shunt stub of distributed element. The proposed circuit on Rogers RT 5880 is designed and measured to verify the new design concept. For accurate comparison, the phase shift line of the conventional Wilkinson power divider is added to one of output ports, and the proposed circuit is fabricated with 45° and 90° power divider at 1.5 GHz central frequency. The fractional bandwidth of the proposed 45° and 90° power divider in case of ±10° phase deviation is over 120% and 100%, respectively. Therefore, the measured results are in good agreement with the design method, and the proposed one will be much smaller size than 90° or 180° hybrid couplers. The proposed Wilkin‐ son power divider will be applicable for phase shifter and various microwave circuits. [ABSTRACT FROM AUTHOR]

Docetaxel (DTX) has poor solubility, low specificity, and severe side effects. For efficient targeting of DTX to hepsin-overexpressing SKOV3 ovarian cancer cells, PEGylated and RIPL peptide (IPLVVPLRRRRRRRRC)-conjugated nanostructured lipid carriers (PEG-RIPL-NLCs) were examined for in vitro and in vivo antitumor efficacy. DTX-loaded plain NLCs (DTX-pNLCs), RIPL-NLCs (DTX-RIPL-NLCs), and PEG-RIPL-NLCs (DTX-PEG-RIPL-NLCs) were prepared using a solvent emulsification-evaporation technique. DTX was successfully loaded with high encapsulation efficiency (>93%), and all NLCs showed homogeneous dispersion with zeta potentials varying from −17 to 15 mV. Drug release was biphasic: initial rapid release, then gradual release. In vitro cytotoxicity was time- and dose-dependent: DTX-RIPL-NLCs and DTX-PEG-RIPL-NLCs exhibited greater cytotoxicity, enhanced cell apoptosis owing to the cell cycle arrest in the G2/M phase, and increased activation of the mitochondria-related intrinsic apoptosis pathway compared to DTX-pNLCs. Pharmacokinetic experiments in male Sprague-Dawley rats revealed that DTX-PEG-RIPL-NLCs increased the mean residence time of DTX but reduced total body clearance and volume of distribution. In a SKOV3-bearing xenograft Balb/c athymic mouse model, DTX-PEG-RIPL-NLCs suppressed tumors, evidenced by tumor volume change and histopathological examination. Thus, we conclude that PEG-RIPL-NLCs have an advantage of high payload of poorly water-soluble drugs and are a good candidate for drug targeting to SKOV3-derived ovarian cancer. [ABSTRACT FROM AUTHOR]

Charcot–Marie–Tooth disease type 1A (CMT1A) is caused by 1.5-fold increased dosage of the PMP22 ; however, onset age and severity vary considerably among patients. The exact reason behind these phenotypic heterogeneities has rarely been discovered yet. Because miRNAs are the key regulators of gene expression, we speculated that variants of miRNAs might be the genetic modifiers for CMT1A. This study noticed a common single nucleotide polymorphism (n.86T > C, rs2292832) in the miR-149 which was predicted to target several CMT causing genes including PMP22 . The rs2292832 was located near the 3′ end of the precursor microRNA of the miR-149 . We performed an association study between the rs2292832 polymorphism and clinical phenotypes of CMT1A in subjects consisting of 176 unrelated Korean CMT1A patients and 176 controls. From this study, we observed that rs2292832 was closely associated to the onset age and severity of CMT1A. Particularly, the TC and CC genotypes were significantly associated with late onset and mild symptom. Therefore, we suggest that the rs2292832 variant in the miR-149 is a potential candidate as a genetic modifier which affects the phenotypic heterogeneity of CMT1A. This study may provide the first evidence that polymorphism in the miR gene is associated with the CMT1A phenotype. [ABSTRACT FROM AUTHOR]

Spondyloepimetaphyseal dysplasia with joint laxity (SEMDJL), leptodactylic (lepto-SEMDJL) or Hall type, is an autosomal-dominant skeletal dysplasia manifesting with short stature, joint laxity with dislocation(s), limb malalignment, and spinal deformity. Its causative gene mutation has not yet been discovered. We captured and sequenced the exomes of eight affected individuals in six unrelated kindreds (three individuals in a family and five simplex individuals). Five novel sequence variants in KIF22, which encodes a member of the kinesin-like protein family, were identified in seven individuals. Sanger sequencing of KIF22 confirmed that c.443C>T (p.Pro148Ser) cosegregated with the phenotype in the affected individuals in the family; c.442C>T (p.Pro148Leu) or c.446G>A (p.Arg149Gln) was present in four of five simplex individuals, but was absent in unaffected individuals in their family and 505 normal cohorts. KIF22 mRNA was detected in human bone, cartilage, joint capsule, ligament, skin, and primary cultured chondrocytes. In silico analysis of KIF22 protein structure indicates that Pro148 and Arg149 are important in maintaining hydrogen bonds in the ATP binding and motor domains of KIF22. We conclude that these mutations in KIF22 cause lepto-SEMDJL. [Copyright &y& Elsevier]

Marine-sponge-derived spicule microparticles (SPMs) possess unique structural and compositional features suitable for bone tissue engineering. However, significant challenges remain in establishing their osteogenic mechanism and practical application in animal models. This study explores the biomimetic potential of SPM in orchestrating biomineralization behavior and modulating the Yes-associated protein 1/transcriptional coactivator with PDZ-binding motif (YAP/TAZ) pathway both in vitro and in vivo. Characterization of SPM revealed a structure comprising amorphous silica oxide mixed with collagen and trace amounts of calcium and phosphate ions, which have the potential to facilitate biomineralization. Structural analysis indicated dynamic biomineralization from SPM to hydroxyapatite, contributing to both in vitro and in vivo osteoconductions. In vitro assessment demonstrated dose-dependent increases in osteogenic gene expression and bone morphogenetic protein-2 protein in response to SPM. In addition, focal adhesion mediated by silica diatoms induced cell spreading on the surface of SPM, leading to cell alignment in the direction of SPM. Mechanical signals from SPM subsequently increased the expression of YAP/TAZ, thereby inducing osteogenic mechanotransduction. The osteogenic activity of SPM-reinforced injectable hydrogel was evaluated in a mouse calvaria defect model, demonstrating rapid vascularized bone regeneration. These findings suggest that biomimetic SPM holds significant promise for regenerating bone tissue., Competing Interests: Competing interests: S.-H.K. has a patent pending for marine-sponge-derived spicules. All other authors declare that they have no competing interests., (Copyright © 2024 Sumi Choi et al.)

Background: Epidural steroid injections are widely used to treat spinal and radiating pain. However, crystal formation has recently been reported in mixtures of ropivacaine and nonparticulate steroids, commonly used in epidural steroid injections., Objectives: Our study assessed the physicochemical stability of mixtures of different nonparticulate steroids and ropivacaine and aimed to propose a safe regimen for epidural steroid injections., Study Design: An in vitro protocol was used to examine the physicochemical stability of epidural steroid injection mixtures most commonly used at our institution., Setting: In vitro laboratory study., Methods: Twelve solutions were prepared by mixing 0.75% or 0.2% ropivacaine with dexamethasone or betamethasone at volume ratios of 1:1, 2:1, and 3:1 in propylene syringes at 24°C. The physical properties of the mixtures were observed with the naked eye and under a microscope, and their pH was measured. The concentration of each drug in the mixture was evaluated using high-performance liquid chromatography., Results: None of the ropivacaine and dexamethasone mixtures showed macroscopic or microscopic crystal formation after 2 hours, and there were no significant changes in pH. The concentrations of the 2 drugs remained stable for up to 2 hours. In contrast, at least 10 mu-m crystals were observed microscopically and macroscopically in all mixtures of ropivacaine and betamethasone; the ropivacaine concentration was reduced by > 10% after one hour., Limitations: Confirming the stability of drugs in vitro does not ensure that their pharmacokinetics and pharmacodynamics remain unaltered in vivo., Conclusion: The combination of ropivacaine and betamethasone should be avoided because of their physicochemical instability. Combinations of ropivacaine and dexamethasone should be administered cautiously because they are more physicochemically stable than combinations of ropivacaine and betamethasone.

This study investigated the room-temperature compressive property and deformation behavior of microporous STS 316L stainless steel tube for catalyst manufactured with powder sintering after two-way compression molding. The microporous tube was manufactured using STS 316L powder stocks with an outer diameter of 30 mm, inner diameter of 25 mm and length of 120 mm. In initial microstructure observed from different directions and locations, the porosity was measured as 32%, and the relative density obtained using micro-computed tomography was 0.54. Phase analysis did not identify phases other than γ -Fe. In a room temperature compression test, compressive yield strength measured 32 MPa. Observation of fractpgraphy after compression test revealed that dimples were formed at the powder-powder interface during the process where necks were disconnected. Based on the above findings, this study attempted to identify the deformation behavior of microporous STS 316L material manufactured with powder sintering after two-way compression molding and powder sintering process.

As a platform for hepsin-specific drug delivery, we previously prepared IPLVVPLRRRRRRRRC peptide (RIPL)-conjugated nanostructured lipid carriers (RIPL-NLCs) composed of Labrafil ® M 1944 CS (liquid oil) and Precirol ® ATO 5 (solid lipid). In this study, to prevent the recognition by the mononuclear phagocyte system, polyethylene glycol (PEG)-modified RIPL-NLCs (PEG-RIPL-NLCs) were prepared using PEG3000 at different grafting ratios (1, 5, and 10 mole %). All prepared NLCs showed a homogeneous dispersion (130⁻280 nm), with zeta potentials varying from -18 to 10 mV. Docetaxel (DTX) was successfully encapsulated in NLCs: encapsulation efficiency (93⁻95%); drug-loading capacity (102⁻109 µg/mg). PEG-RIPL-NLCs with a grafting ratio of 5% PEG or higher showed significantly reduced protein adsorption and macrophage phagocytosis. The uptake of PEG(5%)-RIPL-NLCs by cancer cell lines was somewhat lower than that of RIPL-NLCs because of the PEG-induced steric hindrance; however, the uptake level of PEG-RIPL-NLCs was still greater than that of plain NLCs. In vivo biodistribution was evaluated after tail vein injection of NLCs to normal mice. Compared to RIPL-NLCs, PEG(5%)-RIPL-NLCs showed lower accumulation in the liver, spleen, and lung. In conclusion, we found that PEG(5%)-RIPL-NLCs could be a promising nanocarrier for selective drug targeting with a high payload of poorly water-soluble drugs.

Two dimeric sesquiterpenes were separated from Chloranthus japonicus Sieb. and identified as shizukaols C and F. They exhibited potent antifungal activities (MICs = 4-16 μg/ml) in vitro against various plant pathogenic fungi ( Pythium ultimum, Phytophthora infestans, Botrytis cinerea, Colletotrichum lagenarium, Alternaria kikuchiana, and Magnaporthe grisea ). Shizukaol C showed 88% and 91% protective activities in the greenhouse against Puccinia recondita (wheat leaf rust) and Phytophthora infestans (tomato late blight), respectively, at 100 μg/ml; shizukaol F exhibited 93% antifungal activity against Puccinia recondita at the same concentration. Therefore, these compounds might serve as interesting candidates for effective antifungal agents.

Apios americana Medik (hereinafter Apios) has been reported to treat diseases, including cancer, hypertension, obesity, and diabetes. The therapeutic effect of Apios is likely to be associated with its anti-inflammatory activity. This study was conducted to evaluate the protective effects of Apios in animal models of acute lung injury induced by lipopolysaccharide (LPS) or pandemic H1N1 2009 influenza A virus (H1N1). Mice were exposed to LPS or H1N1 for 2-4 days to induce acute lung injury. The treatment groups were administered Apios extracts via oral injection for 8 weeks before LPS treatment or H1N1 infection. To investigate the effects of Apios, we assessed the mice for in vivo effects of Apios on immune cell infiltration and the level of pro-inflammatory cytokines in the bronchoalveolar lavage (BAL) fluid, and histopathological changes in the lung. After induction of acute lung injury, the numbers of neutrophils and total cells were lower in the Apios-treated groups than in the non-Apios-treated LPS and H1N1 groups. The Apios groups tended to have lower levels of tumor necrosis factor-a and interleukin-6 in BAL fluid. In addition, the histopathological changes in the lungs were markedly reduced in the Apios-treated groups. These data suggest that Apios treatment reduces LPS- and H1N1-induced lung inflammation. These protective effects of Apios suggest that it may have therapeutic potential in acute lung injury.

To identify plant-derived cell signaling inhibitors with antifungal properties, a twocomponent screening system using both wild-type Cryptococcus neoformans and a calcineurin mutant was employed owing to their counter-regulatory actions on the Hog1 mitogenactivated protein kinase and calcineurin pathways. Of the 2,000 plant extracts evaluated, a single bioactive compound from M. obovata Thunb. was found to act specifically on the calcineurin pathway of C. neoformans. This compound was identified as magnoloside A, and had potent antifungal activities against various Cryptococcus strains with minimum inhibitory concentration values ranging from 1.0 to 4.0 μg/ml.

Objective: Transpedicular screw fixation has some disadvantages such as postoperative back pain through wide muscle dissection, long operative time, and cephalad adjacent segmental degeneration (ASD). The purposes of this study are investigation and comparison of radiological and clinical results between interspinous fusion device (IFD) and pedicle screw., Methods: From Jan. 2008 to Aug. 2009, 40 patients underwent spinal fusion with IFD combined with posterior lumbar interbody fusion (PLIF). In same study period, 36 patients underwent spinal fusion with pedicle screw fixation as control group. Dynamic lateral radiographs, visual analogue scale (VAS), and Korean version of the Oswestry disability index (K-ODI) scores were evaluated in both groups., Results: The lumbar spine diseases in the IFD group were as followings; spinal stenosis in 26, degenerative spondylolisthesis in 12, and intervertebral disc herniation in 2. The mean follow up period was 14.24 months (range; 12 to 22 months) in the IFD group and 18.3 months (range; 12 to 28 months) in pedicle screw group. The mean VAS scores was preoperatively 7.16±2.1 and 8.03±2.3 in the IFD and pedicle screw groups, respectively, and improved postoperatively to 1.3±2.9 and 1.2±3.2 in 1-year follow ups (p<0.05). The K-ODI was decreased significantly in an equal amount in both groups one year postoperatively (p<0.05). The statistics revealed a higher incidence of ASD in pedicle screw group than the IFD group (p=0.029)., Conclusion: Posterior IFD has several advantages over the pedicle screw fixation in terms of skin incision, muscle dissection and short operative time and less intraoperative estimated blood loss. The IFD with PLIF may be a favorable technique to replace the pedicle screw fixation in selective case.

In the course of search for potent chitin synthase inhibitors from plant extracts, the chitin synthase 2 inhibitors, O-methyl pisiferic acid and 8,20-dihydroxy-9(11),13-abietadien-12-one which have diterpene skeleton, were isolated from the leaves of Chamaecyparis pisifera. These compounds inhibited chitin synthase 2 of Saccharomyces cerevisiae with the IC50 values of 5.8 and 226.4 microM, respectively. Especially, O-methyl pisiferic acid showed 15.3-fold stronger inhibitory activity than polyoxin D (IC50=88.6 microM), a well-known chitin synthase inhibitor. These compounds exhibited weaker inhibitory activities against chitin synthase 1 than chitin synthase 2, whereas it showed no inhibitory activity for chitin synthase 3. The compound exhibited mixed competitive inhibition with respect to UDP-N-acetyl-D-glucosamine as substrate (Ki=5 microM). These results indicated that O-methyl pisiferic acid is a specific inhibitor of chitin synthase 2. The compound also inhibited chitin synthase 1 of Candida albicans, which represents analogues to chitin synthase 2 of S. cerevisiae, with an IC50 of 75.6 microM, which represents 1.8-fold weaker activity than that of polyoxin D. Although O-methyl pisiferic acid has been reported for antibacterial and insecticidal activities, the present study is the first report on its inhibitory activity against chitin synthase 2.

Potent chitin synthase 2 inhibitors, methyllinderone (1), linderone (2) and kanakugiol (3) were isolated from the stem bark of L. erythrocarpa Makino (Lauraceae). These compounds inhibited chitin synthase 2 with IC(50) values of 23.3, 21.4 and 23.8 microg/mL, respectively. Methyllinderone (1) and linderone (2) exhibited no inhibitory activities for chitin synthases 1 and 3 from S. cerevisiae, and chitin synthase 1 from Candida albicans up to the concentration of 280 microg/mL, while kanakugiol (3) exhibited very weak activity against chitin synthase 1 of C. albicans with an IC(50) of 160 microg/mL. All of the compounds showed moderate to weak antifungal activities against various pathogenic fungi (MIC: 8 - >128 microg/mL) including Cryptococcus neoformans, Aspergillus fumigatus, and Colletotrichum lagenarium. The results indicate that these compounds are specific inhibitors of chitin synthase 2 and can potentially serve as antifungal agents.

In the course of search for potent chitin synthase inhibitors from natural resources, a novel chitin synthases inhibitor, 2'-benzoyloxycinnamaldehyde (2'-BCA) (I), was isolated from the aerial parts of Pleuropterus ciliinervis NAKAI. 2'-BCA inhibited chitin synthase 1 and 2 of Saccharomyces cerevisiae with the IC50s of 54.9 and 70.8 microg/ml, respectively, whereas it exhibited no inhibitory activity for chitin synthase 3 up to 280 microg/ml. Its derivatives, 2'-chloro- (V) and 2(-bromo-cinnamaldehyde (VI), each showed 1.9 and 2.7-fold stronger inhibitory activities than 2'-BCA, with the IC50s of 37.2 and 26.6 microg/ml, respectively. Especially, the IC50 of compound VI against chitin synthase 2 represented 1.7-fold more potent inhibitory activity than polyoxin D, a well-known chitin synthase inhibitor. Furthermore, compounds V and VI showed potent antifungal activities against various fungi including human pathogenic fungi, with a particularly strong inhibitory activity against Cryptococcus neoformans (MIC = 16 microg/ml). Although the chemical synthesis of this compound has been reported, the present study is the first report to describe the isolation of 2'-BCA from natural resources and chitin synthases inhibitory activities of its derivatives. These results suggested that 2'-BCA and its derivatives can potentially serve as useful lead compounds for development of antifungal agents.

Hyperpolarization-activated cation currents (I(h)) have been identified in neurons in the central nervous system, including the retina. There is growing evidence that these currents, mediated by the hyperpolarization-activated cyclic nucleotide-gated cation channel (HCN), may play important roles in visual processing in the retina. This study was conducted to identify and characterize HCN1-immunoreactive (IR) bipolar cells by immunocytochemistry, quantitative analysis, and electron microscopy. The HCN1-IR bipolar cells were a subtype of OFF-type cone bipolar cells and comprised 10% of the total number of cone bipolar cells. The axons of the HCN1-IR cone bipolar cells ramified narrowly in the border of strata 1 and 2 of the inner plexiform layer (IPL). These cells formed a regular distribution, with a density of 1,825 cells/mm(2) at a position 1 mm ventral to the visual streak, falling to 650 cells/mm(2) in the ventral periphery. Double-labeling experiments demonstrated that their axons stratified narrowly within and slightly proximal to the OFF-starburst amacrine cell processes. In the IPL, they were presynaptic to amacrine cell processes. The most frequent postsynaptic dyads formed of HCN1-IR bipolar cell axon terminals are pairs composed of both amacrine cell processes. These results suggest that these HCN1-IR cone bipolar cells might be the same as the DAPI-Ba1 bipolar population, and might therefore be involved in a direction-selective mechanism, providing inputs to the OFF-starburst amacrine cells and/or the OFF-plexus of the ON-OFF ganglion cells., (Copyright 2003 Wiley-Liss, Inc.)