Loureirin A is a narrow-spectrum antimicrobial agent against Helicobacter pylori

Currently, Helicobacter pylori eradication by antibiotic therapy faces various challenges, including antibiotic resistance, side effects on intestinal commensal bacteria, and patient compliance. In this study, loureirin A (LrA), a traditional Chinese medicine monomer extracted from Sanguis Draconis flavones, was found to possess specific antibacterial activity against H. pylori without the bacteria displaying a tendency to develop resistance in vitro. LrA demonstrated a synergistic or additive effect when combined with omeprazole (a proton pump inhibitor) against H. pylori. The combination of LrA and omeprazole showed promising anti-H. pylori potential, exhibiting notable in vivo efficacy comparable to standard triple therapy in mouse models infected with both drug-sensitive and drug-resistant H. pylori strains. Moreover, the narrow-spectrum antibacterial profile of LrA is reflected in its minimal effect on the diversity and composition of the mouse gut microbiota. The underlying mechanism of action of LrA against H. pylori involves the generation of bactericidal levels of reactive oxygen species, resulting in apoptosis-like cell death. These findings indicate that LrA is a promising lead compound targeting H. pylori without harming the commensal bacteria.

Design, Synthesis, and Biological Evaluation of 5-(5-Iodo-2-isopropyl-4-methoxyphenoxy)pyrimidine-2,4-diamine (AF-353) Derivatives as Novel DHFR Inhibitors against Staphylococcus aureus

The high lethality of Staphylococcus aureus infections and the emergence of antibiotic resistance make the development of new antibiotics urgent. Our previous work identified a hit compound h1 (AF-353) as a novel Mycobacterium tuberculosis (Mtb) dihydrofolate reductase (DHFR) inhibitor. Herein, we analyzed the antimicrobial profile of h1 and performed a comprehensive structure-activity relationship (SAR) assay based on h1. The representative compound j9 exhibited potent antibacterial activity against S. aureus without cross-resistance to other antimicrobial classes. Multiple genetic and biochemical approaches showed that j9 directly binds to SaDHFR, resulting in strong inhibition of its enzymatic activity (IC50 = 0.97 nM). Additionally, j9 had an acceptable in vivo safety profile and oral bioavailability (F = 40.7%) and also showed favorable efficacy in a mouse model of methicillin-resistant S. aureus (MRSA) skin infection. Collectively, these findings identified j9 as a novel SaDHFR inhibitor with the potential to combat drug-resistant S. aureus infections.

Repurposing a human acetyl-CoA carboxylase inhibitor firsocostat to treat fungal candidiasis alone and in combination

Opportunistic fungal infections, particularly caused by Candida albicans, remain a common cause of high morbidity and mortality in immunocompromised patients. The escalating prevalence of antifungal drug resistance necessitates the immediate exploration of alternative treatment strategies to combat these life-threatening fungal diseases. In this study, we investigated the antifungal efficacy of firsocostat, a human acetyl-CoA carboxylase (ACC) inhibitor, against C. albicans. Firsocostat alone displayed moderate antifungal activity, while combining it with voriconazole, itraconazole, or amphotericin B exhibited synergistic effects across almost all drug-sensitive and drug-resistant C. albicans strains tested. These observed synergies were further validated in two mouse models of oropharyngeal and systemic candidiasis, where the combination therapies demonstrated superior fungicidal effects compared to monotherapy. Moreover, firsocostat was shown to directly bind to C. albicans ACC and inhibit its enzymatic activity. Sequencing spontaneous firsocostat-resistant mutants revealed mutations mapping to C. albicans ACC, confirming that firsocostat has retained its target in C. albicans. Overall, our findings suggest that repurposing firsocostat, either alone or in combination with other antifungal agents, holds promising potential in the development of antifungal drugs and the treatment of candidiasis.

Killing of Staphylococcus aureus persisters by a multitarget natural product chrysomycin A

Staphylococcus aureus poses a severe public health problem as one of the vital causative agents of healthcare- and community-acquired infections. There is a globally urgent need for new drugs with a novel mode of action (MoA) to combat S. aureus biofilms and persisters that tolerate antibiotic treatment. We demonstrate that a benzonaphthopyranone glycoside, chrysomycin A (ChryA), is a rapid bactericide that is highly active against S. aureus persisters, robustly eradicates biofilms in vitro, and shows a sustainable killing efficacy in vivo. ChryA was suggested to target multiple critical cellular processes. A wide range of genetic and biochemical approaches showed that ChryA directly binds to GlmU and DapD, involved in the biosynthetic pathways for the cell wall peptidoglycan and lysine precursors, respectively, and inhibits the acetyltransferase activities by competition with their mutual substrate acetyl-CoA. Our study provides an effective antimicrobial strategy combining multiple MoAs onto a single small molecule for treatments of S. aureus persistent infections.

Armeniaspirol A: a novel anti-Helicobacter pylori agent

Antibiotic resistance in Helicobacter pylori has been growing worldwide with current treatment regimens. Development of new compounds for treatment of H. pylori infections is urgently required to achieve a successful eradication therapy in the future. Armeniaspirols, a novel class of natural products isolated from Streptomyces armeniacus, have been previously identified as antibacterial agents against Gram‐positive pathogens. In this study, we found that armeniaspirol A (ARM1) exhibited potent antibacterial activity against H. pylori, including multidrug‐resistant strains, with MIC range values of 4–16 μg ml^‐1. The underlying mechanism of action of ARM1 against H. pylori involved the disruption of bacterial cell membranes. Also, ARM1 inhibited biofilm formation, eliminated preformed biofilms and killed biofilm‐encased H. pylori in a dose‐dependent manner. In a mouse model of multidrug‐resistant H. pylori infection, dual therapy with ARM1 and omeprazole showed efficient in vivo killing efficacy comparable to the standard triple therapy, and induced negligible toxicity against normal tissues. Moreover, at acidic pH 2.5, ARM1 exhibited a much more potent anti‐H. pylori activity than metronidazole. Thus, these findings demonstrated that ARM1 is a novel potent anti‐H. pylori agent, which can be developed as a promising drug lead for treatment of H. pylori infections.

In vitro activity of new tetracycline analogues omadacycline and eravacycline against clinical isolates of Helicobacter pylori collected in China

Omadacycline and eravacycline are newly approved tetracycline analogues with excellent activity against a broad spectrum of Gram-positive and Gram-negative microorganisms; however, no data are available regarding Helicobacter pylori. The susceptibility of 201 clinical isolates of H. pylori collected in China to omadacycline, eravacycline, and the comparator tetracycline was determined by an agar dilution method. They showed greater activity than tetracycline. The MIC_50/90 values of omadacycline, eravacycline, and tetracycline were 0.125/0.25 μg/mL, 0.063/0.125 μg/mL, and 0.25/1 μg/mL, respectively. Omadacycline and eravacycline were potent in vitro against all the isolates tested, including tetracycline-resistant strains, and warrant further investigation as potential antibiotics for H. pylori treatment.

A back-door Phenylalanine coordinates the stepwise hexameric loading of acyl carrier protein by the fatty acid biosynthesis enzyme β-hydroxyacyl-acyl carrier protein dehydratase (FabZ)

The fatty acid biosynthesis pathway (FAS) was a fundamental procedure to generate a diversity of lipid components for cellular metabolism in bacteria, while the mechanism of substrate recognition remains unclear. The β-hydroxyacyl-acyl carrier protein dehydratase hexamer (FabZ) is an essential module in the elongation cycle of type-II FAS, catalyzing the dehydration of β-hydroxyacyl-lipid substrate carried by the holo form acyl carrier protein (holo-ACP). We previously elucidated an alternating seesaw-like ACP loading manner within a FabZ dimer subunits, mediated by a front-door residue Tyrosine (Tyr100). Here, we demonstrated that a back-door residue Phenylalanine (Phe83) of FabZ regulates the stepwise hexameric loading of ACP. Our finding represents clues as to the dynamic ACP recognition and catalysis mechanism of dehydratase in fatty acid biosynthesis, and provides critical information for developing antimicrobials targeting the dehydratase module in fatty acid biosynthesis pathway.

Low Gilbert Damping Constant in Perpendicularly Magnetized W/CoFeB/MgO Films with High Thermal Stability

Perpendicular magnetic materials with low damping constant and high thermal stability have great potential for realizing high-density, non-volatile, and low-power consumption spintronic devices, which can sustain operation reliability for high processing temperatures. In this work, we study the Gilbert damping constant (α) of perpendicularly magnetized W/CoFeB/MgO films with a high perpendicular magnetic anisotropy (PMA) and superb thermal stability. The α of these PMA films annealed at different temperatures (T_ann) is determined via an all-optical Time-Resolved Magneto-Optical Kerr Effect method. We find that α of these W/CoFeB/MgO PMA films decreases with increasing T_ann, reaches a minimum of α = 0.015 at T_ann = 350 °C, and then increases to 0.020 after post-annealing at 400 °C. The minimum α observed at 350 °C is rationalized by two competing effects as T_ann becomes higher: the enhanced crystallization of CoFeB and dead-layer growth occurring at the two interfaces of the CoFeB layer. We further demonstrate that α of the 400 °C-annealed W/CoFeB/MgO film is comparable to that of a reference Ta/CoFeB/MgO PMA film annealed at 300 °C, justifying the enhanced thermal stability of the W-seeded CoFeB films.

Methyl bromide as a quarantine treatment for Anoplophora glabripennis (Coleoptera: Cerambycidae) in regulated wood packing material

Anoplophora glabripennis (Motschulsky), has recently (since 1996) established in limited infestations near several cities in the United States. A. glabripennis was probably introduced into the United States with solid wood packing or dunnage. During 2001, we evaluated the current APHIS Schedule T404-b-1-1 for methyl bromide (MeBr) fumigation. Fumigations were conducted in 432-liter Lexan chambers inside a 6.1-m refrigerated container. Each fumigation consisted of 12 high-moisture, naturally infested Populus spp. timbers. We fumigated wood for 24 h at 4.4 degrees C (80 g/m3), 10.0 degrees C (64 g/m3), 15.6 degrees C (56 g/m3), and 21.1 degrees C (48 g/m3). All schedule doses resulted in 100% kill of A. glabripennis larvae. During 2002, we conducted additional fumigations to determine the basic toxicity of MeBr to A. glabripennis larvae in solid wood timbers of 10 by 10 by 115-cm size. Probit analysis estimated the CxT product at 99.0, 99.9, 99.99, and 99.99683% kill (probit-9). The probit-9 values for CxT were 1,196.1, 918.7, 642.4, and 362.4 g-h/m3 at 4.4, 10.0, 15.6, and 21.1 degrees C, respectively. Applied doses to achieve this level of control were estimated to be 119.6, 82.7, 56.0, and 32.2 g/m3, respectively. These applied doses are satisfactory for wood as a commodity with wood load factors of approximately 25% and may be higher than necessary for container fumigation where sorptive wood load as crating or pallets may only be 5% or less. The APHIS Schedule T404-b-1-1 is adequate if extended for 24 h and should be amended to include intermediate doses at 10.0 and 15.6 degrees C, thus reducing the use of MeBr at these temperatures.

Production and characterisation of gilthead sea bream (Sparus auratus) recombinant parathyroid hormone related protein

The production and purification of gilthead sea bream recombinant parathyroid hormone related protein [sbPTHrP(1-125)] using an Escherichia coli system and one step purification process with continuous elution gel electrophoresis is reported. The cDNA encoding sbPTHrP(1-125) was cloned into a prokaryotic expression vector pET-11a. The recombinant plasmid was used to transfect E. coli BL21(DE3) pLysS and sbPTHrP(1-125) synthesis was induced by addition of 1mM isopropyl-beta-d-thiogalactopyranoside. The rapid one step isolation method gave pure sbPTHrP(1-125) as judged by SDS-PAGE and yielded up to 40mg/L of culture medium (3.3mg protein/g of bacteria). The bioactivity of recombinant sbPTHrP(1-125) assessed using an in vitro scale bioassay was found to be equipotent to PTHrP(1-34) in stimulating cAMP accumulation. Assessment of the immunological reactivity of the isolated protein by Western blot revealed it cross-reacts with antisera specific for the N-terminal and C-terminal region of PTHrP. In a radioimmunoassay specific for piscine N-terminal (1-34aa) PTHrP, the recombinant sbPTHrP(1-125) was equipotent with PTHrP(1-34) in displacing labelled (125)I-PTHrP(1-36) PTHrP from the antisera. The availability of recombinant sbPTHrP will allow the development of region specific assays and studies aimed at defining post-secretory processing of this protein and its biological activity in fish.

A geometric deformable model for echocardiographic image segmentation

Gradient vector flow (GVF), an elegant external force for parametric deformable models, can capture object boundaries from both sides. A new geometric deformable model is proposed that combines GVF and the geodesic active contour model. The level set method is used as the numerical method of this model. The model is applied for echocardiographic image segmentation.

PCR cloning of type II polyhydroxyalkanoate biosynthesis genes from two Pseudomonas strains

Two polyhydroxyalkanoate synthase genes, phaC1 from Pseudomonas pseudoalcaligenes HBQ06 and phaC2 from Pseudomonas nitroreducens 0802, were cloned using a PCR cloning strategy based on the type II pha loci property of Pseudomonas strains. The complete open reading frames (ORFs) of phaC1 (P. nitroreducens HBQ06) and phaC2 (P. nitroreducens 0802) were identified from the PCR products. Using the sequence information, the complete PHA synthase genes were PCR cloned directly from the genomic DNA and expressed in Escherichia coli as confirmed by Fourier transform-infrared spectroscopy and gas chromatography. The differences between PhaC1 and PhaC2 were analyzed and the two proteins were suggested to contain different functions and evolution history.

Compression of echocardiographic scan line data using wavelet packet transform

An efficient compression strategy is indispensable for digital echocardiography. Previous work has suggested improved results utilizing wavelet transforms in the compression of 2D echocardiographic images. Set partitioning in hierarchical trees (SPIHT) was modified to compress echocardiographic scanline data based on the wavelet packet transform. A compression ratio of at least 94:1 resulted in preserved image quality.

[Study of modeling and simulation of the multi-branch cardiovascular system]

By the Power Band Graph(PBG) method, this paper presents a computer simulation model of the multi-branch cardiovascular circulation system, which describes the blood fluid dynamic law in the cardiovacular system by the state equation. The model gives a minute description on physiological characters of cardiovascular circulation system (CVS). An integrate computer model on CVS has been established. The model can simulate physiological characters of cardiovascular circulation system and get the simulation data and the curves of CVS hemodynamics variables. The model can be used widely in the field of physiological system simulation study, medical study, and computer-aided instruction.

Compression of real time volumetric echocardiographic data using modified SPIHT based on the three-dimensional wavelet packet transform

Real-time three-dimensional echocardiography has been introduced to provide improved quantification and description of cardiac function. Data compression is desired to allow efficient storage and improve data transmission. Previous work has suggested improved results utilizing wavelet transforms in the compression of medical data including 2D echocardiogram. Set partitioning in hierarchical trees (SPIHT) was extended to compress volumetric echocardiographic data by modifying the algorithm based on the three-dimensional wavelet packet transform. A compression ratio of at least 40:1 resulted in preserved image quality.

Impact of temporal resolution on flow quantification by real-time 3D color Doppler echocardiography: numerical modeling and animal validation study

Real-time, 3D color Doppler echocardiography (RT3D) is capable of quantifying flow at the LV outflow tract (LVOT). However, previous works have found significant underestimation for flow rate estimation due to finite scanning time (ST) of the color Doppler. The authors have, therefore, developed a mathematical model to correct the impact of ST on flow quantification and validated it by an animal study. Scanning time to cover the entire cross-sectional image of the LVOT was calculated as 60 ms, and the underestimation due to temporal averaging effect was predicted as 18 +/- 7%. In the animal experiment, peak flow rates were obtained by spatially integrating the velocity data front the cross-sectional color images of the LVOT. By applying a correction factor, there was an excellent agreement between reference flow rate by an electromagnetic flow meter and RT3D (angstroms=-5.6 ml/s, r=0.93), which was significantly better than without correction (p<0.001). Real-time, color 3D echocardiography was capable of quantifying flow accurately by applying the mathematical correction.

The lef-3 gene of Autographa californica nuclear polyhedrosis virus encodes a single-stranded DNA-binding protein

The Autographa californica nuclear polyhedrosis virus (AcNPV) replicates in the nuclei of infected cells and encodes several proteins required for viral DNA replication. As a first step in the functional characterization of viral replication proteins, we purified a single-stranded DNA-binding protein (SSB) from AcNPV-infected insect cells. Nuclear extracts were chromatographed on single-stranded DNA agarose columns. An abundant protein with an apparent molecular weight of 43,000 was eluted from the columns at 0.9 to 1.0 M NaCl. This protein was not evident in extracts prepared from control cells, suggesting that the SSB was encoded by the virus. SSB bound to single-stranded DNA in solution, and binding was nonspecific with respect to base sequence, as single-stranded vector DNA competed as efficiently as single-stranded DNA containing the AcNPV origin of DNA replication. Competition binding experiments indicated that SSB showed a preference for single-stranded DNA over double-stranded DNA. To determine whether SSB was encoded by the lef-3 gene of AcNPV, the lef-3 open reading frame was cloned under the control of the bacteriophage T7 promoter. Immunochemical analyses indicated that LEF-3 produced in bacteria or in rabbit reticulocyte lysates specifically reacted with antiserum produced by immunization with purified SSB. Immunoblot analyses of infected cell extracts revealed that SSB/LEF-3 was detected by 4 h postinfection and accumulated through 48 h postinfection.