• The Korean Journal of Physiology
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• 제23권1호
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• pp.51-66
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• 1989

Mammalian cardiocytes secrete atrial natriuretic peptides (ANPs) into plasma, which cause marked natriuresis, diuresis, vasorelaxation and inhibition of hormone secretions. Aging influences the ability of the kidney both to conserve and to excrete sodium; i.e., in old animals, the excretory capacity of sodium is reduced and the time required to excrete sodium load is prolonged. Therefore, it is possible that animals differing in ages may respond differently to ANP. In the present study, we determined whether the renal, hormonal and vascular effects of ANP may be influenced by aging in conscious rabbits. The plasma renin concentration decreased with aging but plasma ANP concentration was significantly lower only in 24-month-old rabbits. Plasma aldosterone concentration and atrial ANP content did not change by aging. In 1-month-old rabbits, ANP (atriopeptin III, 3 ug/kg) administered intravenously caused hypotension and decreased in plasma renin and aldosterone concentrations, but did not cause diuresis and natriuresis. In 2 to 5 month-old rabbits, ANP caused hypotension, decreases in Plasma renin and aldosterone concentrations and marked renal effects. However, in 24-month-old rabbits, all the above effects of ANP was blunted. With hydration of physiological saline at a rate of 15 ml/kg/h for 2hr, urine volume and glomerular filtration rate did not change but the electrolyte excretion as well as fractional excretion of sodium significantly increased. The plasma concentrations of active renin and aldosterone were decreased but plasma inactive renin and ANP concentrations were increased. The changes in renal function and plasma level of hormone showed no differences in different ages. These results suggest that the peripheral vascular receptors to ANP may develop earlier than those in the kidney, and the attenuated vascular and renal responses to ANP in the old age may be due to age-related modifications in renal function and blood vessel.

• The Korean Journal of Pain
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• 제32권4호
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• pp.271-279
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• 2019

Background: We utilized diffusion tensor imaging (DTI) to evaluate the cerebral white matter changes that are associated with phantom limb pain in patients with unilateral arm amputation. It was anticipated that this would complement previous research in which we had shown that changes in cerebral blood volume were associated with the cerebral pain network. Methods: Ten patients with phantom limb pain due to unilateral arm amputation and sixteen healthy age-matched controls were enrolled. The intensity of phantom limb pain was measured by the visual analogue scale (VAS) and depressive mood was assessed by the Hamilton depression rating scale. Diffusion tensor-derived parameters, including fractional anisotropy, mean diffusivity, axial diffusivity (AD), and radial diffusivity (RD), were computed from the DTI. Results: Compared with controls, the cases had alterations in the cerebral white matter as a consequence of phantom limb pain, manifesting a higher AD of white matter in both hemispheres symmetrically after adjusting for individual depressive moods. In addition, there were associations between the RD of white matter and VAS scores primarily in the hemispheres related to the missing hand and in the corpus callosum. Conclusions: The phantom limb pain after unilateral arm amputation induced plasticity in the white matter. We conclude that loss of white matter integrity, particularly in the hemisphere connected with the missing hand, is significantly correlated with phantom limb pain.

• Korean Journal of Radiology
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• 제19권6호
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• pp.1161-1171
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• 2018

Objective: The aim of this study was to investigate diffusion tensor (DT) imaging-derived properties of benign oligemia, true "at risk" penumbra (TP), and the infarct core (IC) during the first 3 hours of stroke onset. Materials and Methods: The study was approved by the local animal care and use committee. DT imaging data were obtained from 14 rats after permanent middle cerebral artery occlusion (pMCAO) using a 7T magnetic resonance scanner (Bruker) in room air. Relative cerebral blood flow and apparent diffusion coefficient (ADC) maps were generated to define oligemia, TP, IC, and normal tissue (NT) every 30 minutes up to 3 hours. Relative fractional anisotropy (rFA), pure anisotropy (rq), diffusion magnitude (rL), ADC (rADC), axial diffusivity (rAD), and radial diffusivity (rRD) values were derived by comparison with the contralateral normal brain. Results: The mean volume of oligemia was $24.7{\pm}14.1mm^3$, that of TP was $81.3{\pm}62.6mm^3$, and that of IC was $123.0{\pm}85.2mm^3$ at 30 minutes after pMCAO. rFA showed an initial paradoxical 10% increase in IC and TP, and declined afterward. The rq, rL, rADC, rAD, and rRD showed an initial discrepant decrease in IC (from -24% to -36%) as compared with TP (from -7% to -13%). Significant differences (p < 0.05) in metrics, except rFA, were found between tissue subtypes in the first 2.5 hours. The rq demonstrated the best overall performance in discriminating TP from IC (accuracy = 92.6%, area under curve = 0.93) and the optimal cutoff value was -33.90%. The metric values for oligemia and NT remained similar at all time points. Conclusion: Benign oligemia is small and remains microstructurally normal under pMCAO. TP and IC show a distinct evolution of DT-derived properties within the first 3 hours of stroke onset, and are thus potentially useful in predicting the fate of ischemic brain.