Background: Stroke is accompanied by a distinguished inflammatory reaction that is initiated by the infiltration of immunocytes, expression of cytokines, and other inflammatory mediators. As natural killer cells (NK cells) are a type of cytotoxic lymphocyte critical to the innate immune system, we investigated the mechanism of NK cells-induced brain injuries after cerebral ischemia and the chemotactic effect of IP-10 simultaneously. Methods: NK cells infiltration, interferon-gamma (IFN-γ) and IP-10 expression were detected by immunohistochemistry, immunofluorescence, PCR and flow cytometry in human and C57/BL6 wild type mouse ischemic brain tissues. The ischemia area was detected via 2,3,5-triphenyltetrazolium chloride staining. CXCR3 mean fluorescence intensity of isolated NK cells was measured by flow cytometry. The neuronal injury made by NK cells was examined via apoptosis experiment. The chemotactic of IP-10 was detected by migration and permeability assays. Results: In human ischemic brain tissue, infiltrations of NK cells were observed and reached a peak at 2 to 5 days. In a permanent middle cerebral artery occlusion (pMCAO) model, infiltration of NK cells into the ischemic infarct region reached their highest levels 12 hours after ischemia. IFN-γ-positive NK cells and levels of the chemokine IP-10 were also detected within the ischemic region, from 6 hours up to 4 days after pMCAO was performed, and IFN-γ levels decreased after NK cells depletion in vivo. Co-culture experiments of neural cells with NK cells also showed that neural necrosis was induced via IFN-γ. In parallel experiments with IP-10, the presence of CXCR3 indicates that NK cells were affected by IP-10 via CXCR3, and the effect was dose-dependent. After IP-10 depletion in vivo, NK cells decreased. In migration assays and permeability experiments, disintegration of the blood-brain barrier (BBB) was observed following the addition of NK cells. Moreover, in the presence of IP-10 this injury was aggravated. Conclusions: All findings support the hypothesis that NK cells participate in cerebral ischemia and promote neural cells necrosis via IFN-γ. Moreover, IP-10 intensifies injury to the BBB by NK cells via CXCR3.

Blood velocity measured in the middle cerebral artery (MCA) increases with finite kinetics during moderate-intensity exercise, and the amplitude and dynamics of the response provide invaluable insights into the controlling mechanisms. The MCA response after exercise onset is well fit to an exponential model in young individuals but remains to be characterized in their older counterparts. The responsiveness of vasomotor control degrades with advancing age, especially in skeletal muscle. We tested the hypothesis that older subjects would evince a slower and reduced MCA response to exercise. Twenty-nine healthy young (25 ± 1 yr old) and older (69 ± 1 yr old) adults each performed a rapid transition from rest to moderate-intensity exercise on a recumbent stepper. Resting MCA was lower in older than young subjects (47 ± 2 vs. 64 ± 3 cm/s, P < 0.001), and amplitude from rest to steady-state exercise was lower in older than young subjects (12 ± 2 vs. 18 ± 3 cm/s, P = 0.04), even after subjects were matched for work rate. As hypothesized, the time constant was significantly longer (slower) in the older than young subjects (51 ± 10 vs. 31 ± 4 s, P = 0.03), driven primarily by older women. Neither age-related differences in fitness, end-tidal CO, nor blood pressure could account for this effect. Thus, MCA kinetic analyses revealed a marked impairment in the cerebrovascular response to exercise in older individuals. Kinetic analysis offers a novel approach to evaluate the efficacy of therapeutic interventions for improving cerebrovascular function in elderly and patient populations. NEW & NOTEWORTHY Understanding the dynamic cerebrovascular response to exercise has provided insights into sex-related cerebrovascular control mechanisms throughout the aging process. We report novel differences in the kinetics response of cerebrovascular blood velocity after the onset of moderate-intensity exercise. The exponential increase in brain blood flow from rest to exercise revealed that 1) the kinetics profile of the older group was blunted compared with their young counterparts and 2) the older women demonstrated a slowed response.

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ObjectiveTo explore the association between glycated hemoglobin (A1C) variability and renal disease progression in patients with diabetes mellitus.MethodsA comprehensive search was performed using the PubMed and Embase databases (up to April 26, 2014). The hazard ratio (HR) was pooled per unit increase in the standard deviation of A1C (A1C-SD) to evaluate the dose-response relationship between A1C-SD and the risk of nephropathy.ResultsEight studies with a total of 17,758 subjects provided the HR for A1C-SD and were included in the final meta-analysis. The pooled HR results demonstrated that A1C-SD was significantly associated with the progression of renal status (HR for both T1DM and T2DM 1.43, 95% confidence interval [CI] 1.24–1.64; HR for T1DM 1.70, 95%CI 1.41–2.05; HR for T2DM 1.20, 95%CI 1.12–1.28). A1C-SD was significantly correlated with new-onset microalbuminuria (HR for T1DM 1.63, 95%CI 1.28–2.07; HR for T2DM 1.23, 95%CI 1.08–1.39). These outcomes were also supported in subgroup analyses. Furthermore, sensitivity analyses demonstrated that the results were robust.ConclusionsA1C variability is independently associated with the development of microalbuminuria and the progression of renal status in both type 1 and 2 diabetes patients. A standard method for measuring A1C variability is essential for further and deeper analyses. In addition, future studies should assess the effect of reducing A1C variability on nephropathy complication.

Despite its necessity for understanding healthy brain aging, the influence of exercise intensity on cerebrovascular kinetics is currently unknown. We, therefore characterized middle cerebral artery blood flow velocity (MCAv) kinetics associated with two exercise intensities: low and moderate. We hypothesized that increasing exercise intensity would increase the MCAv amplitude response (Amp) and that age and estimated fitness (VȮ2max) would be related to Amp. Baseline (BL) values were collected for 90-seconds followed by a 6-minute exercise bout. Heart rate, end-tidal CO 2 , mean arterial pressure and MCAv were recorded throughout. MCAv kinetics were described by Amp, time delay (TD) and time constant (τ). Sixty-four adults completed the study. Amp was greater during moderate compared to low exercise intensity (p<0.001) while no difference was observed in either TD (p=0.65) or τ (p=0.47). Amp was negatively associated with age (p<0.01) and positively correlated with estimated VȮ2max (p<0.01). Although Amp declines with age, maintaining higher VȮ2max may benefit the cerebrovascular response to exercise.

Moyamoya disease (MMD) and Moyamoya syndrome (MMS) are referring to a progressive steno-occlusive vasculopathy at terminal portions of the bilateral internal carotid arteries and their proximal branches with prominent collateral artery formation. They can be found throughout the world and cause irreversible damage to the cerebral hemodynamics due to the progressive nature. Prompt diagnosis and accurate assessment could significantly improve the prognosis of MMD and MMS. Some imaging modalities could be used for diagnosis and nonquantitative evaluation of MMD and MMS, such as conventional computed tomography (CT) and magnetic resonance imaging (MRI), digital subtraction angiography, CT angiography (CTA), and magnetic resonance angiography. Some could quantitatively evaluate the cerebral hemodynamics of MMD and MMS, such as single-photon emission CT, positron emission tomography, xenon-enhanced CT, perfusion CT, dynamic susceptibility contrast MRI, arterial spin labeling MRI, and the hemodynamic parameters measured by those imaging methods could guide treatment of MMD and MMS. All the imaging modalities have their merits and demerits, and they can play a part in certain situation. We need establish standardized protocols for preoperative and postoperative evaluation with different imaging techniques in the further science for MMD and MMS.

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