• Neonatal Medicine
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• 제25권1호
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• pp.1-6
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• 2018

Extremely low birth weight infants remain at increased risk of intraventricular hemorrhage from the fragile vascular bed of the germinal matrix; the roles of hypotension (ischemia) and reperfusion (hyperemia) in the development of intraventricular hemorrhage are still debated. Cerebrovascular pressure autoregulation protects the brain by maintaining constant cerebral blood flow despite changes in blood pressure. The ontogeny of cerebrovascular pressure autoregulation has not been well established and uncertainty remains about the optimal arterial blood pressure required to support brain perfusion. Another important aspect of premature cerebral hemodynamics is the critical closing pressure--the arterial blood pressure at which cerebral blood flow ceases. Interestingly, in premature infants, the critical closing pressure approximates the mean arterial blood pressure. Often in this unique population, cerebral blood flow occurs only during systole when the diastolic arterial blood pressure is equal to the critical closing pressure. Moreover, the diastolic closing margin, a metric of cerebral perfusion that normalizes diastolic arterial blood pressure to the critical closing pressure, may be a better measure than arterial blood pressure for defining cerebral perfusion in premature infants. Elevated diastolic closing margin has been associated with intraventricular hemorrhage. This review summarizes the current state of understanding of cerebral hemodynamics in premature infants.

• 대한의생명과학회지
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• 제10권4호
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• pp.467-472
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• 2004

Transcranial Doppler sonography (TCD) is a useful diagnostic method to measure cerebral blood flow velocity in various cerebral disorders. However, we haven't data enough to be available for young persons, especially in the twenties in Korea. This study was performed to collect the basic data of the cerebral blood flow velocity and to understand the cerebral physiology in the twenties. We determined the mean velocities of middle, anterior, and posterior cerebral artery, and vertebral and basilar artery (MCA-V, ACA-V, PCA-V, VA-V, and BA-V, respectively) in eighty-two healthy volunteers. For evaluating cerebral autoregulation, only the MCA- V was measured under various conditions such as stable, apnea, and hyperventilation state. Right and left MCA-V were 80.66±14.03 and 83.22±14.40 cm/sec at stable state, 90.13±17.47 and 90.26±16.38 cm/sec at apnea, and 54.83±11.09 and 55.33±10.74 cm/sec at hyperventilation. Right and left ACA-V were 49.11±15.71 and 48.19±13.75 cm/sec. Right and left PCA-V were 39.44±9.12 and 37.91±6.74 cm/sec. Right and left VA-V were 33.65±9.26 and 36.l8±10.39 cm/sec. BA-V was 48.49±11.16 cm/sec. Right and left MCA- V, V A-V, and right ACA- V and PCA- V in women were higher than those of men (P<0.05). No significant differences were found between men and women in the others. These findings indicate that cerebral hemodynamics and autoregulation were normal in young people in their twenties. The velocities of MCA, ACA, PCA, and BA were high values in women as compared with men.

• The Korean Journal of Physiology and Pharmacology
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• 제2권5호
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• pp.573-580
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• 1998

The study aims to identify the mechanism (s) underlying the altered vasodilatory responses of the pial artery of spontaneously hypertensive rats (SHR) under a hypothesis that calcitonin gene-related peptide (CGRP) exerts a modulator role in the autoregulation of cerebral blood flow (CBF). The animals were divided into four groups: 1) Sprague-Dawley rats (SDR), 2) Wistar rats (WR), 3) SHR with high blood pressure $(BP{\ge}150\;mmHg),$ and 4) SHR with normotensive BP $({\le}150\;mmHg).$ The lower limit of CBF autoregulation in SHR shifted to a higher BP $(82.8{\pm}9.3\'mmHg,\;P<0.05)$ than that in SDR $(58.9{\pm}5.7\;mmHg)$. In SHR, whether the BP levels were high or normotensive, the vasodilator responses to a stepwise hypotension were significantly attenuated unlike with SDR and WR. When artificial cerebrospinal fluid (CSF) containing capsaicin $(3{\times}10^{-7}\;M)$ was suffused over the cortical surface, a transient increase in pial arterial diameter was observed in the SHR with high or normotensive BP. In contrast, SDR and WR showed a large increase in diameter, and the increase was sustained for over 10 minutes. In line with these results, the basal releases of CGRP-like immunoreactivity (CGRP-LI) in the isolated pial arteries from SHR with high and normotensive BP were $12.5{\pm}1.4\;and\;9.8{\pm}2.8\;fmole/mm^2/60\;min\;(P<0.05)$, while those from SDR and WR were $25.5{\pm}3.1\;and\;24.6{\pm}3.1\;fmole/mm^2/60\;min,$ respectively. The isolated basilar arteries showed similar results to those of the pial arteries in SHR. Thus, it is summarized that, in the SHR, the reduced autoregulatory vasodilator responses to stepwise hypotension and capsaicin may be, in part, ascribed to the decreased release of CGRP from the perivascular sensory nerve fibers of the pial arteries, and that altered vasomotor activity in SHR may not be related with the hypertensive tone.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.287-287
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• 1994

In the present study, it was aimed to asses the possibility that calcitonin gene-related peptide (CGRP) released in response to transient hypotension may contribute to the reflex autoregulation of cerebral blood flow as a putative modulator. Changes in pial arterial diameter (mean, 33.0 ${\pm}$ 1.1 $\mu\textrm{m}$) with changes in systemic arterial blood pressure (mean, 101.9 ${\pm}$ 2.7 mmHg) were observed directly through a closed cranial window in anesthetized normotensive rats. Image of the pial vessels was captured with a stereoscope connected to a CCD video camera and the diameter was measured with a microscaler. In the capsaicin-treated rats (one day prior to experiment, 50 nmol capsaicin injected intracisternally), both vasodilater and vasoconstrictor responses evoked by a transient hypotension and the reverse of blood pressure were markedly attenuated or almost abolished. When changes in pial arterial diameter were plotted as a function of changes in blood pressure, the slopes of both regression lines (for vasodilators and vasoconstrictors ) were markedly reduced. Similar reductions were evidenced under treatment wi th the CGRP antibody serum (1:1,000) and following CGRP receptor desensitization. However, the autoregulatory mechanics were neither affected by treatment wi th spantide (1 ${\mu}$M), substance P antagonist, nor by substance P receptor desensitization. Suffusion wi th mock cerebrospinal fluid containing CGRP and cromakalim caused a vasodilatation in a concentration-dependent manner, respectively and their effects were antagonized by glibenclamide. Substance P produced a vasodilatation, which was, however, little affected by glibenclamide. These observations indicate that the CGRP released from the perivascular sensory fibers in response to a hypotension is implicated in the modulation of the autoregulation of cerebral blood flow.

• 대한임상검사과학회지
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• 제36권1호
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• pp.43-48
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• 2004

Cerebral vasoreactivity is an index of autoregulation of cerebral perfusion, and can be measured using functional images such as Xe CT, SPECT and PET in reponse to hypercapneic stimulus. In order to measure cerebral $CO_2$ vasoreactivity in routine TCD study conveniently and reliably, we devised a method of rebreathing into closed volume of reservoir bag as a hypercapneic stimulus, and applied it to 44 healthy volunteers. As a hypercapneic stimulus, we applied fitting mask connected with closed reservoir bag for about 90 seconds, and mean blood flow velocity(MBFV) and pulsatility index(PI) were evaluated at proximal middle cerebral arteries(MCA) of 50-55 mm depth, before and after the hypercapneic stimulus. Age affected the MFV and PI value showed significant and the MFV was 56.45(SD=9.75)cm/sec, while PI was 0.406(SD=0.089). As age increases the flow velocity decreased significantly whereas PI value increased(P<0.05). The vasoreactvity significantly decreased with age(P<0.05). The decrease of cerebral blood flow quantity and cerebral blood flow velocity is not only because of increase of diameter of cerebrovascular resulting from aging, but the resistance increase of small blood vessel resulting from the increase of PI & RI value is regarded. We suppose that the rebreathing method is a reliable and convenient technique as a hypercapneic stimulus in determining cerebral $CO_2$ vasoreactivity. The rebreathing method could be non-invasive and useful methods in estimation of the cerebrovascular reactivity and could be applied to the basal and follow-up evaluation of the cerebrovascular reserve of the ischemic stroke patients.

• Childhood Kidney Diseases
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• 제15권1호
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• pp.22-28
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• 2011

고혈압은 소아 청소년시기에 발생하는 흔한 만성질환 중 하나이다. 고혈압을 치료하지 않으면 여러가지 소아의 장기에 악영향을 미칠 수 있다. 여기서는 고혈압이 중추신경계에 미치는 영향에 대해 알아 보았다. 혈압의 변화에 따라 대뇌가 받는 영향은 다른 장기에 비해 덜 하다. 그것은 대뇌 자동 조절 기전때문이다. 즉 혈압의 변화에 따라 뇌혈관의 저항이 변하기 때문에 뇌혈류량이 일정하게 유지 된다. 그러나 이런 자동 조절 기전의 항상성이 파괴되면 급성으로 또는 만성으로 급성 고혈압 뇌병증, 허혈성, 출혈성 뇌경색, 학습 장애와 인지 기능 장애 등이 발생한다. 이에 고혈압이 대뇌에 미치는 영향에 대해 숙지하고 빠른 시일 내에 적절한 치료를 하면 이런 합병증을 예방할 수 있다.

• 생명과학회지
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• 제23권2호
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• pp.157-166
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• 2013

본 연구는 Sprague-Dawley계 숫쥐에서 출생 초기 에탄올에의 노출에 의한 성장 후 뇌혈류 자가조절의 변동을 관찰하고 이러한 변동에 대한 nociceptin의 관여를 관찰하고자 하였다. 실험동물에게 에탄올 2.5 g/kg을 생후 6, 7 및 8일의 3일 동안 2시간 간격으로 1일 2회 피하 주사하였다. 주령 4, 8 및 12주 시기에 단계적 출혈에 의한 저혈압 및 혈액 재주입에 의한 혈압 상승시의 평균동맥혈압의 변동에 따른 국소 뇌혈류 변동을 laser-Doppler flowmetry 방법으로 측정하였고, 경막과 대뇌피질에서 nociceptin-유사 면역반응력의 발현을 면역조직화학법으로 측정하였다. 출생 초기 에탄올 투여는 4, 8 및 12주령 모두에서 국소 뇌혈류 자가조절 기능을 거의 소실시켰다. 에탄올 투여 전에 nociceptin을 전처치한 군에서는 모든 연령군에서 국소 뇌혈류 자가조절 기능이 보존되었으나, nociceptin 수용체 선택적 경쟁적 길항제인 [$Nphe^1$]nociceptin(1-13)$NH_2$를 전처치한 군에서는 보존되지 아니하였다. 출생 초기 에탄올 투여에 의하여 경막 내 nociceptin-유사 면역반응력이 모든 연령군에서 현저히 증가하였고, 7-nitroindazole (7-NINA) 전처치뿐만 아니라 aminoguanidine 전처치에 의하여 모든 주령에서 유의하게 억제되었다. 출생 초기 에탄올 투여에 의하여 대뇌피질 내 nociceptin-유사 면역반응력이 모든 연령군에서 현저히 증가하였고, 7-NINA 전처치와 aminoguanidine 전처치에 의하여 모든 주령에서 유의하게 억제되었다. 모든 실험군의 동맥혈가스분석 결과는 실험 전, 중 및 후에 유의한 차이를 보이지 아니하였다. 이상의 결과로 보아 출생 초기 에탄올 투여는 성장 후 뇌혈류 자가조절에 변동을 초래하고, 이에 대한 보상기전으로서 nociceptin의 발현이 증가하는데, 여기에는 nitric oxide가 깊이 관여하는 것으로 생각된다.

• The Korean Journal of Physiology and Pharmacology
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• 제13권3호
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• pp.257-263
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• 2009

This study aimed to investigate whether selective serotonin reuptake inhibitors (SSRIs) attenuate brain injury and facilitate recovery following photothrombotic cortical ischemia in mice. Male ICR mice were anesthetized and systemically administered Rose Bengal. Permanent focal ischemia was induced in the medial frontal and somatosensory cortices by irradiating the skull with cold light laser. The animals were treated with fluoxetine or sertraline once a day for 14 d starting 1 h after ischemic insult. Treatment with fluoxetine and sertraline significantly reduced the infarct size. The Evans blue extravasation indices of the fluoxetine- and sertraline-treated groups were significantly lower than that of the vehicle group. Treatment with fluoxetine and sertraline shifted the lower limit of the mean arterial blood pressure for cerebral blood flow autoregulation toward normal, and significantly increased the expression of heme oxygenase-1 (HO-1) and hypoxia-inducible factor-1 ${\alpha}$ (HIF-1 ${\alpha}$) proteins in the ischemic region. These results suggest that SSRIs, such as fluoxetine and sertraline, facilitate recovery following photothrombotic cortical ischemia via enhancement of HO-1 and HIF-1 ${\alpha}$ proteins expression, thereby providing a benefit in therapy of cerebral ischemia.

• 대한약리학회지
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• 제31권1호
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• pp.27-37
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• 1995

본 연구에서는 콜린성 기전에 반응하여 분비되는 내피 의존성 이완물질(endothelium-derived relaxing factor, EDRF)나 nitric oxide(NO)가 마취 흰쥐의 뇌혈류 자가조절기전에 관여할 가능성을 관찰하였다. Acetylcholine($10^{-9}-10^{-6}M$)을 포함한 mock 뇌척수액(CSF)을 관류시 뇌연막 동맥은 농도에 의존하여 이완반응 나타내었고(평균; $19.3{\pm}1.7{\mu}m$, n=36), 이러한 이완반응은 $N{\omega}$-nitro-L-arginine(L-NNA, $10^{-5}M$)에 의해서 억제되었을 뿐 아니라 methylene blue($10^{-6}M$)나 oxyhemoglobin($10^{-6}M$)에 의하여도 억제되었다. 한편 이러한 acethlcholine에 의한 뇌연막동맥의 이완반응을 매게하는 무스카린 수용체는 무스카린 수용체 길항제의 봉쇄효과를 관찰한 실험에서 $M_1$과 $M_3$ 아형으로 생각되었다. L-Arginine을 함유한 mock CSF로 관류시 일어나는 일시적인 혈관이완반응은 NY 83583 ($10^{-5}M$)에 강력히 억제되었으나 L-NNA ($10^{-5}M$)에 의해서는 억제되지 아니하였다. 한편 acetylcholine과 L-arginine에 의한 혈관이완반응은 ATP-sensitive $K^+$ 통로 봉쇄제인 glibenclamide에 의해 유의하게 봉쇄되었다. 나아가 뇌연막동맥의 직경 변화를 동맥압의 변화에 대하여 검정한 결과 혈관이완과 혈관수축의 희귀 직선의 경사도는 $10^{-5}M$ L-NNA의 전처치에 의하여 영향을 받지 아니하였으나, $3{\times}10^{-6}M$ glibenclamide에 의해 유의하게 감소되었다. 이러한 결과로 보아 혈압하강에 대해 쥐의 뇌연막동맥에 나타나는 혈관이완반응은 EDRF(NO)에 의해 매개되지 않는다고 사료된다.

• Journal of Korean Neurosurgical Society
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• 제52권5호
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• pp.476-479
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• 2012

Cerebral hyperperfusion syndrome (CHS) is a rare, serious complication of carotid revascularization either after carotid endarterectomy or carotid stent placement. Although extensive effort has been devoted to reducing the incidence of CHS, little is known about the prevention. Postprocedural hypertension is very rare due to autoregulation of carotid baroreceptors but may occur if presented with autonomic dysfunction. We present two cases of CHS after cerebral revascularization that presented autonomic dysfunction.