Publications by authors named "Tomoki Hashimoto"

Background: Aneurysms are one of the most common and yet devastating cerebrovascular diseases after rupture. Despite several decades of scientific advancements including the expansion of the endovascular capabilities and noninvasive imaging modalities, no medical treatment exists to date. This failure is likely largely attributed to the complex and multifactorial nature of aneurysm pathophysiology.

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  • Mitochondrial dysfunction plays a role in cardiovascular diseases, especially hypertension, with a focus on the balance of mitochondrial fission and fusion.
  • In a study using C57BL6 mice, the mitochondrial fission inhibitor mdivi1 was shown to reduce hypertension and related vascular changes induced by angiotensin II.
  • Mdivi1 not only limited vessel fibrosis and hypertrophy but also improved mitochondrial structure and reduced cardiac hypertrophy and vascular reactivity associated with angiotensin II treatment, indicating multiple protective mechanisms in the vasculature.
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Intracranial aneurysms (IAs) are rare vascular lesions that are more frequently found in women. The pathophysiology behind the formation and growth of IAs is complex. Hence, to date, no single pharmacological option exists to treat them.

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Intracranial aneurysm rupture causes severe disability and high mortality. Epidemiological studies show a strong association between decreased vitamin D levels and an increase in aneurysm rupture. However, the causality and mechanism remain largely unknown.

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Background: Multiple pathways and factors are involved in the rupture of intracranial aneurysms. The EGFR (epidermal growth factor receptor) has been shown to mediate inflammatory vascular diseases, including atherosclerosis and aortic aneurysm. However, the role of EGFR in mediating intracranial aneurysm rupture and its underlying mechanisms have yet to be determined.

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  • Iron buildup in blood vessel walls leads to oxidative stress and inflammation, increasing the risk of cerebrovascular issues and aneurysm complications.
  • A mouse model was used to study the impact of an iron-restricted diet on the formation and rupture of intracranial aneurysms, comparing mice on normal diets with those on restricted diets.
  • Results showed that mice on an iron-restricted diet had a significantly lower aneurysm rupture rate (37%) compared to the normal diet group (76%), along with reduced oxidative stress and inflammation markers, indicating that iron plays a critical role in aneurysm rupture.
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Background: Ang II (angiotensin II) type 1 (AT) receptors play a critical role in cardiovascular diseases such as hypertension. Rodents have 2 types of AT receptor (AT and AT) of which knock-in -mediated smooth muscle AT silencing attenuated Ang II-induced hypertension. Although vascular remodeling, a significant contributor to organ damage, occurs concurrently with hypertension in Ang II-infused mice, the contribution of smooth muscle AT in this process remains unexplored.

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Background Investigations into alternative treatments for hypertension are necessary because current treatments cannot fully reduce the risk for the development of cardiovascular diseases. Chronic activation of unfolded protein response attributable to the endoplasmic reticulum stress has been proposed as a potential therapeutic target for hypertension and associated vascular remodeling. Triggered by the accumulation of misfolded proteins, chronic unfolded protein response leads to downstream signaling of cellular inflammation and dysfunction.

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Calcification of intracranial aneurysms is a well-known phenomenon. Whether microsurgical or endovascular techniques are used, calcifications may increase the difficulty of treatment. However, the implications of calcification on aneurysm biology and stability have received little attention.

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In this study, we have looked for an optimum media glucose concentration and compared glucose consumption in three vascular cell types, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and adventitial fibroblasts (AFs) with or without angiotensin II (AngII) stimulation. In a subconfluent 6-well experiment in 1 mL DMEM with a standard low (100 mg/dL), a standard high (450 mg/dL), or a mixed middle (275 mg/dL) glucose concentration, steady and significant glucose consumption was observed in all cell types. After 48-h incubation, media that contained low glucose was reduced to almost 0 mg/dL, media that contained high glucose remained significantly higher at ∼275 mg/dL, and media that contained middle glucose remained closer to physiological range.

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Sarcopenia is defined as the progressive and generalized loss of skeletal muscle mass and strength, which is associated with increased likelihood of adverse outcomes including falls, fractures, physical disability, and mortality. The etiology of sarcopenia has been postulated to be multifactorial with genetics, aging, immobility, nutritional deficiencies, inflammation, stress, and endocrine factors all contributing to the imbalance of muscle anabolism and catabolism. The prevalence of sarcopenia is estimated to range from 13 to 24% in adults over 60 years of age and up to 50% in persons aged 80 and older.

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Background And Purpose: The incidences of intracranial aneurysm and aneurysmal subarachnoid hemorrhage are high in postmenopausal women. Although population-based studies suggest that hormone replacement therapy is beneficial for postmenopausal women with intracranial aneurysms, estrogen replacement may no longer be recommended for the prevention of chronic diseases given its association with adverse outcomes, such as cancer and ischemic stroke. The isoflavone daidzein and its intestinal metabolite equol are bioactive phytoestrogens and potent agonists of estrogen receptors.

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Background And Purpose: Inflammation has emerged as a key component of the pathophysiology of intracranial aneurysms. Mast cells have been detected in human intracranial aneurysm tissues, and their presence was associated with intramural microhemorrhage and wall degeneration. We hypothesized that mast cells play a critical role in the development of aneurysmal rupture, and that mast cells can be used as a therapeutic target for the prevention of aneurysm rupture.

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Cardiovascular disease (CVD) is a prevalent issue in the global aging population. Premature vascular aging such as elevated arterial stiffness appears to be a major risk factor for CVD. Vascular smooth muscle cells (VSMCs) are one of the essential parts of arterial pathology and prone to stress-induced senescence.

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Angiotensin II (AngII) has a crucial role in cardiovascular pathologies, including endothelial inflammation and premature vascular aging. However, the precise molecular mechanism underlying aging-related endothelial inflammation induced by AngII remains elusive. Here, we have tested a hypothesis in cultured rat aortic endothelial cells (ECs) that the removal of AngII-induced senescent cells, preservation of proteostasis, or inhibition of mitochondrial fission attenuates the pro-inflammatory EC phenotype.

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Inflammation is emerging as a critical factor in the pathophysiology of intracranial aneurysm. TLR4 (toll-like receptor 4) contributes not only to the innate immune responses but also to the inflammatory processes associated with vascular disease. Therefore, we examined the contribution of the TLR4 pathway to the development of the rupture of intracranial aneurysm.

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Blood vessels in the CNS form a specialized and critical structure, the blood-brain barrier (BBB). We present a resource to understand the molecular mechanisms that regulate BBB function in health and dysfunction during disease. Using endothelial cell enrichment and RNA sequencing, we analyzed the gene expression of endothelial cells in mice, comparing brain endothelial cells with peripheral endothelial cells.

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Article Synopsis
  • Inflammation plays a significant role in the destabilization and rupture of aneurysms, and targeting it might help prevent these occurrences.
  • A study tested the effects of noninvasive vagus nerve stimulation (VNS) on aneurysm outcomes in mice, revealing that VNS reduced rupture rates and improved survival after rupture compared to a control group.
  • Chronic daily VNS lowered levels of MMP-9, a protein associated with aneurysm growth, without affecting systemic blood pressure, suggesting it could be an effective treatment strategy for aneurysm-related complications.
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Gut microbiota modulates metabolic and immunoregulatory axes and contributes to the pathophysiology of diseases with inflammatory components, such as atherosclerosis, diabetes mellitus, and ischemic stroke. Inflammation is emerging as a critical player in the pathophysiology of an intracranial aneurysm. Therefore, we hypothesized that the gut microbiota affects aneurysm formation by modulating inflammation.

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Background and Purpose- Tobacco cigarette smoking is considered to be a strong risk factor for intracranial aneurysmal rupture. Nicotine is a major biologically active constituent of tobacco products. Nicotine's interactions with vascular cell nicotinic acetylcholine receptors containing α7 subunits (α7*-nAChR) are thought to promote local inflammation and sustained angiogenesis.

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Background And Purpose: Inflammatory cells play a significant role in secondary injury after ischemic stroke. Recent studies have suggested that a lack of autophagy in myeloid cells causes augmented proinflammatory cytokine release and prolonged inflammation after tissue injury. In this study, we investigated the roles of myeloid cell autophagy in ischemic brain injury.

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