Dietary fiber intake and risk of incident disabling dementia: the Circulatory Risk in Communities Study

OBJECTIVES: It has been hypothesized that dietary fiber intake has a beneficial impact on prevention of dementia, but the epidemiological evidence is scant. We sought to examine whether dietary fiber intake is inversely associated with risk of dementia requiring care under the national insurance (disabling dementia). METHODS: The study setting was the Circulatory Risk in Communities Study, involving 3739 Japanese individuals aged 40-64 years at the dietary surveys (1985-99). Dietary fiber intake was estimated using the 24-hour dietary recall method. Incident disabling dementia was followed up from 1999 through 2020. Disabling dementia was further classified into that with or without a history of stroke. Hazard ratios of disabling dementia according to quartiles of total, soluble, and insoluble fiber intake were calculated using the Cox proportional hazards model. RESULTS: During a median 19.7-year follow-up, a total of 670 cases of disabling dementia developed. Dietary fiber intake was inversely associated with risk of dementia: the multivariate hazards ratios (95% confidence intervals) were 0.83 (0.67-1.04), 0.81 (0.65-1.02), and 0.74 (0.57-0.96) for individuals with the second, third, and highest quartiles of dietary fiber intake, respectively, as compared with the lowest quartile (P for trend = 0.03). The inverse association was more evident for soluble fiber intake and was confined to dementia without a history of stroke. As for fiber-containing foods, potatoes, but not vegetables or fruits, showed a similar association. CONCLUSIONS: Dietary fiber intake, especially soluble fiber, was inversely associated with risk of disabling dementia in a general Japanese population

Serum uric acid and risk of stroke and its types: the Circulatory Risk in Communities Study (CIRCS)

The role of serum uric acid as a predictor of stroke among the general Japanese population remains controversial. We conducted a prospective cohort study of 5235 men and 8185 women aged 40-79 years at baseline between 1985 and 1994 in four Japanese communities, who were initially free from stroke, coronary heart disease, and medication for hyperuricemia or gout. Cox proportional hazards models were used to estimate sex-specific hazard ratios of stroke and its types in relation to serum uric acid level. During a median follow-up of 23.1 years, we recorded 1018 (488 men and 530 women) incident strokes, including 222 (99 and 123) intraparenchymal hemorrhages, 113 (33 and 80) subarachnoid hemorrhages and 667 (347 and 320) ischemic strokes. After adjustment for age, community and known cardiovascular risk factors, the multivariable hazard ratios (95% CIs) in the highest vs. lowest quintile of serum uric acid were 1.45 (1.07-1.96) for total stroke, 1.20 (0.65-2.20) for intraparenchymal hemorrhage, 1.46 (0.69-3.09) for subarachnoid hemorrhage and 1.61 (1.07-2.41) for ischemic stroke in women. The corresponding multivariable hazard ratios (95% CIs) in men were 1.02 (0.74-1.35), 0.83 (0.40-1.72), 1.19 (0.38-3.75) and 1.00 (0.70-1.41). Furthermore, those positive associations with risks of total and ischemic strokes in women were more evident in nonusers of antihypertensive medication than the users. In conclusion, elevated serum uric acid level is an independent predictor of total stroke in women but not in men. The positive association in women was mostly attributable to ischemic stroke and was more pronounced among nonusers of antihypertensive medication

L-arginine stimulates fibroblast proliferation through the GPRC6A-ERK1/2 and PI3K/Akt pathway.

L-arginine is considered a conditionally essential amino acid and has been shown to enhance wound healing. However, the molecular mechanisms through which arginine stimulates cutaneous wound repair remain unknown. Here, we evaluated the effects of arginine supplementation on fibroblast proliferation, which is a key process required for new tissue formation. We also sought to elucidate the signaling pathways involved in mediating the effects of arginine on fibroblasts by evaluation of extracellular signal-related kinase (ERK) 1/2 activation, which is important for cell growth, survival, and differentiation. Our data demonstrated that addition of 6 mM arginine significantly enhanced fibroblast proliferation, while arginine deprivation increased apoptosis, as observed by enhanced DNA fragmentation. In vitro kinase assays demonstrated that arginine supplementation activated ERK1/2, Akt, PKA and its downstream target, cAMP response element binding protein (CREB). Moreover, knockdown of GPRC6A using siRNA blocked fibroblast proliferation and decreased phosphorylation of ERK1/2, Akt and CREB. The present experiments demonstrated a critical role for the GPRC6A-ERK1/2 and PI3K/Akt signaling pathway in arginine-mediated fibroblast survival. Our findings provide novel mechanistic insights into the positive effects of arginine on wound healing

Generation of the organotypic kidney structure by integrating pluripotent stem cell-derived renal stroma

Organs consist of parenchyma and stroma. Nishinakamura and colleagues induce renal stromal progenitors from mouse pluripotent stem cells (PSCs), and generate completely PSC-derived organoids that reproduce complex kidney structure

Author Correction: Generation of the organotypic kidney structure by integrating pluripotent stem cell-derived renal stroma

Organs consist of the parenchyma and stroma, the latter of which coordinates the generation of organotypic structures. Despite recent advances in organoid technology, induction of organ-specific stroma and recapitulation of complex organ configurations from pluripotent stem cells (PSCs) have remained challenging. By elucidating the in vivo molecular features of the renal stromal lineage at a single-cell resolution level, we herein establish an in vitro induction protocol for stromal progenitors (SPs) from mouse PSCs. When the induced SPs are assembled with two differentially induced parenchymal progenitors (nephron progenitors and ureteric buds), the completely PSC-derived organoids reproduce the complex kidney structure, with multiple types of stromal cells distributed along differentiating nephrons and branching ureteric buds. Thus, integration of PSC-derived lineage-specific stroma into parenchymal organoids will pave the way toward recapitulation of the organotypic architecture and functions