Publications by authors named "Kiyotaka Nakagawa"

Article Synopsis
  • - The study focuses on using near infrared (NIR) spectroscopy to monitor the oxidation causes in vegetable oil, which is key for quality control.
  • - Researchers quantified triacylglycerol hydroperoxide (TGOOH) isomers linked to different oxidation processes through liquid chromatography-mass spectrometry, achieving high accuracy with partial least square regression.
  • - The findings suggest that this NIR method can swiftly and easily evaluate the quality of various vegetable oils by detecting subtle changes in specific infrared spectral peaks associated with oxidation.
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Liposome lipid peroxidation induced by cold atmospheric pressure plasma jet (CAPPJ) irradiation was investigated. The formation of thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation final products, as a function of irradiation was observed. Lipid radicals, peroxidation reaction intermediates generated by CAPPJ irradiation, were confirmed by increased NBD-pen fluorescence intensity.

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  • - Selenium-dependent glutathione peroxidase 4 (GPX4) is crucial for preventing ferroptosis by reducing harmful phospholipid hydroperoxides, but cells without GPX4 still show some ability to manage these compounds, indicating other enzymes might play a role!* - The study identifies peroxiredoxin 6 (PRDX6), an antioxidant enzyme, as a significant factor in ferroptosis protection, as its absence makes cancer cells more susceptible to ferroptosis, despite its overexpression not preventing it.* - PRDX6 not only reduces phospholipid hydroperoxides but also helps the body utilize selenium effectively for the production of GPX4, as shown by reduced GPX4 levels in mouse brains
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  • The roasting process of sesame oil changes its internal composition, which affects its stability against oxidation, but this effect varies depending on the type of oxidation (thermal or photo).
  • The study compared different sesame oils (raw, refined, and roasted) and rapeseed oils by exposing them to thermal oxidation at 120℃ and photo-oxidation at 50,000 lx for 5 and 10 hours.
  • The findings indicate that roasted sesame oil is more stable during thermal oxidation due to antioxidant changes, while refined sesame oil is more stable under photo-oxidation, highlighting the significant impact of both roasting and refining processes on sesame oil’s oxidative stability.
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Determining the content of the nutrient choline in foods and obtaining the required amount from the diet are crucial. One way to measure choline in foods is by converting choline esters to free choline via acid hydrolysis, followed by quantifying the total choline, as adopted by the AOAC method (AOAC-Choline); however, certain choline esters are difficult to hydrolyse. Here, we investigated various acid hydrolysis conditions to establish a reliable method for determining the total choline in foods by detecting free choline using highly sensitive and selective mass spectrometry.

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Insulin resistance, the hallmark of type 2 diabetes mellitus (T2DM), has emerged as a pathological feature in Alzheimer's disease (AD). Given the shared role of insulin resistance in T2DM and AD, repurposing peripheral insulin sensitizers is a promising strategy to preserve neuronal insulin sensitivity and prevent AD. 1-Deoxynojirimycin (DNJ), a bioactive iminosugar, exhibited insulin-sensitizing effects in metabolic tissues and was detected in brain tissue post-oral intake.

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  • * This study involved administering labeled forms of these acids and their hydroperoxides to mice and measuring the expired CO levels to determine catabolic rates, finding that the hydroperoxides were broken down more quickly than their corresponding fatty acids.
  • * The research suggests that during digestion, these hydroperoxides decompose into medium-chain compounds, which are then quickly absorbed by the liver and metabolized, supporting the idea that dietary lipid hydroperoxides do not enter the intestine intact but
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Recent evidence indicates ferroptosis is implicated in the pathophysiology of various liver diseases; however, the organ-specific regulation mechanism is poorly understood. Here, we demonstrate 7-dehydrocholesterol reductase (DHCR7), the terminal enzyme of cholesterol biosynthesis, as a regulator of ferroptosis in hepatocytes. Genetic and pharmacological inhibition (with AY9944) of DHCR7 suppress ferroptosis in human hepatocellular carcinoma Huh-7 cells.

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Ferroptosis, a regulated cell death hallmarked by unrestrained lipid peroxidation, plays a pivotal role in the pathophysiology of various diseases, making it a promising therapeutic target. Glutathione peroxidase 4 (GPX4) prevents ferroptosis by reducing (phospho)lipid hydroperoxides, yet evaluation of its actual activity has remained arduous. Here, we present a tangible method using affinity-purified GPX4 to capture a snapshot of its native activity.

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Antimicrobial peptides (AMPs) are present in a wide range of plants, animals, and microorganisms. Since AMPs are characterized by their effectiveness against emergent antibiotic-resistant bacteria, they are attracting attention as next-generation antimicrobial compounds that could solve the problem of drug-resistant bacteria. Persulcatusin (IP), an antibacterial peptide derived from the hard tick , shows high antibacterial activity against various Gram- positive bacteria as well as multidrug-resistant bacteria.

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  • Milk is highly nutritious, but lipid oxidation is a key factor in its spoilage, requiring effective prevention measures.
  • The study investigated oxidation mechanisms in long-life milk and analyzed specific lipid oxidation products using advanced techniques.
  • Findings indicate that long-life milk is more prone to photo-oxidation than thermal oxidation, emphasizing the role of radicals and suggesting strategies to prevent oxidation in milk and related products.
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Ever since the proposal of ferroptosis, it has been studied as a nonapoptotic cell death caused by iron ion-dependent phospholipid (PL) peroxidation. We previously showed that treatment of human hepatoma cell line HepG2 with prepared PL hydroperoxide (PLOOH) resulted in ferroptosis. However, in human sebum, the major hydroperoxide is not PLOOH but squalene hydroperoxide (SQOOH), and to our knowledge, it is not established yet whether SQOOH induces ferroptosis in the skin.

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Background: Higher cholesterol absorption has been reported to be related to a higher incidence of cardiovascular events (CVEs). The KEEP (Kyushu Elderly Ezetimibe Phytosterol) study, a substudy of the EWTOPIA 75 (Ezetimibe Lipid-Lowering Trial on Prevention of Atherosclerotic Cardiovascular Disease in 75 or Older) study, investigated the relationships of cholesterol absorption and synthesis markers with CVEs in older old individuals with hypercholesterolemia, particularly in relation to ezetimibe treatment.

Methods And Results: Eligible patients were those aged ≥75 years who had low-density lipoprotein cholesterol ≥140 mg/dL, no history of coronary artery disease, and no recent use of lipid-lowering drugs.

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As known for quite a long time now, even saturated fatty acids can be oxidized at high temperatures to produce unique aroma compounds, such as 2-alkanones and lactones. Hydroperoxide positional isomers with a hydroperoxy group at the 2-, 3-, 4-, or 5-position are hypothesized to be responsible for the formation of these aroma components, but this hypothesis has not been verified. For the first time, this study successfully prepared a series of glyceryl trioctanoate hydroperoxide (C8TG;OOH) isomers.

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Glucosylceramide (GlcCer) belongs to sphingolipids and is found naturally in plant foods and other sources that humans consume daily. Our previous studies demonstrated that GlcCer prevents inflammatory bowel disease both in vitro and in vivo, whose patients are increasing alarmingly. Although some lipids are vulnerable to oxidation which changes their structure and activities, it is unknown whether oxidative modification of GlcCer affects its activity.

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Lipid cyclic peroxides are a rarely reported and documented class of compounds in the human organism. Recently, we reported the formation of squalene (SQ) hydroperoxy cyclic peroxides derived from SQ monohydroperoxide isomers (SQ-OOHs) for the first time. Notably, we successfully detected and quantified cis-2-OOH-3-(1,2-dioxane)-SQ in the human skin.

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Article Synopsis
  • - Sheep play a crucial role in agriculture for wool and meat production, but there are few established cell lines from sheep compared to humans and mice.
  • - Researchers successfully created an immortalized sheep muscle-derived cell line using the K4DT method and SV40 large T oncogene, which helps in sustaining primary cells for research.
  • - The new sheep cell line exhibits biological characteristics similar to ear-derived fibroblasts, offering valuable resources for studies in veterinary medicine and cell biology.
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  • - The study investigates the differences in cellular uptake of Vitamin E forms, tocopherol (Toc) and tocotrienol (T3), focusing on the role of serum albumin as a contributing factor.
  • - Adding bovine serum albumin (BSA) in serum-depleted media increased T3 uptake while decreasing Toc uptake, showing varying effects among different analogs of both forms.
  • - The research indicates that T3 binds to albumin with a higher affinity than Toc, due to variations in side chains, which influences their cellular uptake mechanisms, offering insights into Vitamin E's physiological roles.
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Background: Circulating phospholipid species have been shown to predict Alzheimer's disease (AD) prognosis but the link between phospholipid disturbances and subcortical small vessel cerebrovascular disease (CeVD) common in AD patients is not known.

Objective: Mass-spectrometry lipidomics was applied to quantify serum diacyl, alkenyl (ether), alkyl, and lyso phospholipid species in individuals with extensive CeVD (n = 29), AD with minimal CeVD (n = 16), and AD with extensive CeVD (n = 14), and compared them to age-matched controls (n = 27). Memory was assessed using the California Verbal Learning Test.

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  • The study investigates how different particle sizes of curcumin solid dispersions (C-SDs) affect the bioavailability and biological activities of curcumin (CUR).
  • C-SDs were prepared in sizes ranging from 120 to 1910 nm, and results indicated that smaller C-SDs increased CUR bioavailability when taken orally while larger C-SDs were better for intravenous administration.
  • Findings showed that smaller C-SDs enhance cellular uptake and exhibit stronger anti-inflammatory effects, highlighting the importance of particle size in optimizing curcumin delivery and effectiveness.
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The Ryukyu long-furred rat is an endangered species confined to the southernmost three small islands of Japan (Amami-Oshima, Tokunoshima, and Okinawa). Its population is rapidly decreasing because of roadkill, deforestation, and feral animals. To date, its genomic and biological information are poorly understood.

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  • This study investigates the potential of 4β-Hydroxycholesterol (4β-HC) as a biomarker for assessing the induction of the CYP3A4 enzyme during drug development.
  • The researchers optimized protocols for plasma collection and storage, discovering that inappropriate storage leads to the formation of a cholesterol oxidation product, which can signal when samples are compromised.
  • By effectively measuring 4β-HC levels in their clinical trials with novel drug candidates, they demonstrated that weak CYP3A4 inducers could be detected without needing a probe substrate, enhancing the reliability of drug interaction studies.
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