Publications by authors named "Kei Asai"

Mn is an essential nutrient whose concentration is tightly controlled in bacteria. In Bacillus subtilis, the Mn-activated transcription factor MntR controls Mn transporter genes. However, factors regulating intracellular Mn concentration are incompletely understood.

View Article and Find Full Text PDF

When Bacillus subtilis cells face environmental deterioration, such as exhaustion of nutrients and an increase in cell density, they form spores. It is known that phosphorylation of Spo0A and activation of σ are key events at the initiation of sporulation. However, the initiation of sporulation is an extremely complicated process, and the relationship between these two events remains to be elucidated.

View Article and Find Full Text PDF

Recently, the antibacterial effects of essential oils have been investigated in addition to their therapeutic purposes. Owing to their hydrophobic nature, they are thought to perturb the integrity of the bacterial cell membrane, leading to cell death. Against such antibiotic challenges, bacteria develop mechanisms for cell envelope stress responses (CESR).

View Article and Find Full Text PDF

In a Bacillus subtilis ugtP mutant lacking glucolipids, SigI was activated in the log phase, and the activation of SigI in the mutant was suppressed by the expression of native ugtP. By contrast, SigI was inhibited in a yfnI mutant lacking one of the lipoteichoic acid (LTA) synthase genes, and the inhibition was suppressed by the expression of yfnI. A series of mutation analyses of the sigI promoter revealed that the two WalR binding sites were involved in the increase of P -lacZ activity in the ugtP mutant and decrease of the lacZ activity in the yfnI mutant.

View Article and Find Full Text PDF

Background: Since 2020, peoples' lifestyles have been largely changed due to the COVID-19 pandemic worldwide. In the medical field, although many patients prefer remote medical care, this prevents the physician from examining the patient directly; thus, it is important for patients to accurately convey their condition to the physician. Accordingly, remote medical care should be implemented and adaptable home medical devices are required.

View Article and Find Full Text PDF

Ribosomal protein S14 can be classified into three types. The first, the C+ type has a Zn binding motif and is ancestral. The second and third are the C- short and C- long types, neither of which contain a Zn binding motif and which are ca.

View Article and Find Full Text PDF

Background: The detection of wheezes as an exacerbation sign is important in certain respiratory diseases. However, few highly accurate clinical methods are available for automatic detection of wheezes in children. This study aimed to develop a wheeze detection algorithm for practical implementation in children.

View Article and Find Full Text PDF

Background: Wheezing is a typical symptom of respiratory conditions. Few objective methods are available for predicting sleep disturbance in young children with wheezing.

Objective: We investigated whether wheezing characteristics, detected by lung-sound analysis, were associated with risk of sleep disturbance.

View Article and Find Full Text PDF

In bacteria, guanosine (penta)tetra-phosphate ([p]ppGpp) is essential for controlling intracellular metabolism that is needed to adapt to environmental changes, such as amino acid starvation. The (p)ppGpp strain of Bacillus subtilis, which lacks (p)ppGpp synthetase, is unable to form colonies on minimal medium. Here, we found suppressor mutations in the (p)ppGpp strain, in the purine nucleotide biosynthesis genes, prs, purF and rpoB/C, which encode RNA polymerase core enzymes.

View Article and Find Full Text PDF

Steroid inhalation is the standard bronchial asthma therapy and it includes powdered metered doses, dry powder, and nebulizer suspension. However, particle sizes vary widely. The research goal was to demonstrate that different budesonide administration forms and devices have various deposition rates in the airway obstruction region.

View Article and Find Full Text PDF

The differences in the mechanical properties between the cortex and coat protein layer in a Bacillus subtilis spore were clarified using an atomic force microscope (AFM) and an originally developed laser-induced surface deformation (LISD) microscope. AFM force curve measurements show that the Young's modulus of the coat protein layer is ca. 66% lower compared with that of the cortex.

View Article and Find Full Text PDF

Proteins belonging to the sigma factor family in eubacteria initiate transcription by associating with RNA polymerase. A subfamily, the extracytoplasmic function (ECF) sigma factors, which form a widely distributed bacterial signal transduction system comprising a sigma factor and a cognate membrane-embedded anti-sigma factor, regulates genes in response to stressors that threaten cell envelope integrity including the cell wall and membrane. The Gram-positive soil bacterium Bacillus subtilis provides a valuable model for investigation of the ECF sigma factors.

View Article and Find Full Text PDF

The biosynthesis of iron-sulfur (Fe-S) clusters in Bacillus subtilis is mediated by the SUF-like system composed of the sufCDSUB gene products. This system is unique in that it is a chimeric machinery comprising homologues of E. coli SUF components (SufS, SufB, SufC and SufD) and an ISC component (IscU).

View Article and Find Full Text PDF

SufU is a zinc-containing protein involved in mobilization of sulfur from SufS for iron-sulfur cluster biogenesis of Bacillus subtilis. Structural basis for the sulfur transfer in SufS-SufU complex was revealed. A zinc-ligand exchange reaction upon SufS-SufU complexation provides a free thiol from Cys41 of SufU as a sulfur acceptor.

View Article and Find Full Text PDF

Among inhaled asthma therapies, the present study aimed to identify factors for selecting the type of inhalation therapy for asthma. Three methods are used to deliver inhaled cromoglycate, and the airway deposition rate was evaluated using a cascade impactor with 3 dosage forms: dry powder (DP), pressurized metered dose inhaler (pMDI), and solution (jet- and mesh-types). The percentage of particles with diameters of 2-6 m was 17.

View Article and Find Full Text PDF

Extracytoplasmic function (ECF) σ factors have roles related to cell envelope and/or cell membrane functions, in addition to other cellular functions. Without cell-surface stresses, ECF σ factors are sequestered by the cognate anti-σ factor, leading to inactivation and the resultant repression of regulons due to the inhibition of transcription of their own genes. has seven ECF σ factors including σ and σ that transcribe their own structural genes.

View Article and Find Full Text PDF
Article Synopsis
  • The study aimed to create and validate grading scales for diagnosing meibomian gland dysfunction (MGD) to ensure consistency in clinical settings.
  • Researchers conducted a multicenter study, evaluating photographs of patients with MGD and controls, leading to the development of new grading scales based on specific eye signs.
  • Results showed good reliability among experts and general ophthalmologists when using the scales, indicating they are effective for MGD diagnosis and can be utilized in clinical trials.
View Article and Find Full Text PDF

To examine the relation between changes in the free fatty acid (FFA) composition of human meibum and both objective signs and subjective symptoms of meibomian gland dysfunction (MGD), we analyzed the FFA content of meibum collected from both MGD patients and control subjects. Thirty-eight patients with MGD (13 men and 25 women; mean age ± SD, 66.9 ± 15.

View Article and Find Full Text PDF

Purpose: We measured the components of meibum in patients with meibomian gland dysfunction (MGD) and control subjects and then examined the relation between meibum composition and clinical parameters.

Methods: Thirty-eight patients with MGD (13 men and 25 women; mean age ± SD, 66.9 ± 15.

View Article and Find Full Text PDF

The main challenge in antitumor chemotherapy is to enhance the curative effect and minimize the adverse effects of an anticancer drug. Administration of functionalized magnetic iron oxide nanoparticles is one of the strategies to improve sensitivity to cancer chemotherapy, and these nanoparticles are attractive materials that have been widely used in medicine for various applications, including diagnostic imaging and therapeutic applications. In this study, we describe the synthesis and characterization of drug-loaded iron oxide nanoparticles.

View Article and Find Full Text PDF

Bacteria have developed various strategies for phage resistance. Infection with phage induces the transcription of part of the phage resistance gene, but the regulatory mechanisms of such transcription remain largely unknown. The phage resistance gene nonA is located on the SPβ prophage region of the Bacillus subtilis Marburg strain genome.

View Article and Find Full Text PDF

Bacteria are equipped with complex cell surface structures, such as cell walls. How they maintain cell surface integrity through cell wall metabolism during growth and adaptation to unfavorable environmental conditions is still elusive. In the Gram-positive soil bacterium Bacillus subtilis, one extracytoplasmic function (ECF) sigma factor, SigM, is believed to play a primary role in cell surface integrity.

View Article and Find Full Text PDF

Lipoteichoic acid (LTA) is an important cell envelope component of Gram-positive bacteria. Bacillus subtilis has four homologous genes for LTA synthesis: ltaS (yflE), yfnI, yqgS and yvgJ. The products LtaS (YflE), YfnI and YqgS are bona fide LTA synthetases, whereas YvgJ functions only as an LTA primase.

View Article and Find Full Text PDF

SecA is an ATP-driven motor for protein translocation in bacteria and plants. Mycobacteria and listeria were recently found to possess two functionally distinct secA genes. In this study, we found that Cyanidioschyzon merolae, a unicellular red alga, possessed two distinct secA-homologous genes; one encoded in the cell nucleus and the other in the plastid genome.

View Article and Find Full Text PDF

This paper describes the preparation of iron oxide nanoparticles, surface of which was coated with extremely high immobilization stability and relatively higher density of poly(ethylene glycol) (PEG), which are referred to as PEG protected iron oxide nanoparticles (PEG-PIONs). The PEG-PIONs were obtained through alkali coprecipitation of iron salts in the presence of the PEG-poly(4-vinylbenzylphosphonate) block copolymer (PEG-b-PVBP). In this system, PEG-b-PVBP served as a surface coating that was bound to the iron oxide surface via multipoint anchoring of the phosphonate groups in the PVBP segment of PEG-b-PVBP.

View Article and Find Full Text PDF