Absence of glutathione peroxidase-1 exacerbates cerebral ischemia-reperfusion injury by reducing post-ischemic microvascular perfusion

Mice deficient in the anti-oxidant enzyme glutathione peroxidase-1 (Gpx1) have a greater susceptibility to cerebral injury following a localized ischemic event. Much of the response to ischemia-reperfusion is caused by aberrant responses within the microvasculature, including inflammation, diminished endothelial barrier function (increased vascular permeability), endothelial activation, and reduced microvascular perfusion. However, the role of Gpx1 in regulating these responses has not been investigated. Wild-type and Gpx1-/- mice underwent focal cerebral ischemia via mid-cerebral artery occlusion followed by measurement of cerebral perfusion via laser Doppler and intravital microscopy. Post-ischemic brains in wild-type mice displayed significant deficit in microvascular perfusion. However, in Gpx1-/- mice, the deficit in cerebral blood flow was significantly greater than that in wild-type mice, and this was associated with significant increase in infarct size and increased vascular permeability. Ischemia-reperfusion also resulted in expression of matrix metalloproteinase-9 (MMP-9) in endothelial cells. The absence of Gpx1 was associated with marked increase in pro-MMP-9 expression as well as potentiated MMP-9 activity. Pre-treatment of Gpx1-/- mice with the anti-oxidant ebselen restored microvascular perfusion, limited the induction and activation of MMP-9, and attenuated the increases in infarct size and vascular permeability. These findings demonstrate that the anti-oxidant function of Gpx1 plays a critical role in protecting the cerebral microvasculature against ischemia-reperfusion injury by preserving microvascular perfusion and inhibiting MMP-9 expression.     

Combination therapy with transductive anti-death FNK protein and FK506 ameliorates brain damage with focal transient ischemia in rat

Many practical therapies have been explored as clinical applications for ischemic cerebral infarction; however, most are still insufficient to treat acute stroke. We show here a potential combination therapy in a rat focal ischemic model to improve neurological symptoms as well as to reduce infarct volumes at the maximum level. We applied protein transduction technology using artificial anti-death Bcl- x _l derivative with three amino acid-substitutions (Y22 F , Q26 N and R165 K ) (FNK) protein fused with a protein-transduction-domain peptide (PTD-FNK). When PTD-FNK was administrated 1 h after initiating ischemia followed by the administration of an immunosuppressant FK506 with a 30-min time lag, infarct volumes of the total brain and cortex were markedly reduced to 27% and 14%, respectively. This procedure not only reduced the infarct volume and edema, but also markedly improved neurological symptoms. The therapeutic effect continued for at least 1 week after ischemia. FK506 inhibited the transduction of PTD-FNK in vitro , which explains the requirement of a time lag for the administration of FK506. An additional in vitro experiment showed that PTD-FNK, when administered 30 min before FK506, gave the maximal protective effect by reducing the intracellular calcium concentration. We propose that this combination therapy would provide a synergistic protective effect by both drugs, reducing adverse the effects of FK506.     

雨蛙素联合脂多糖致小鼠重症急性胰腺炎模型的建立及其机理的探讨

为建立一种快速、简便、无创伤性的小鼠重症急性胰腺炎模型。本实验运用雨蛙素联合脂多糖小鼠腹腔内给药;血淀粉酶和胰腺湿重测定;胰腺和胰外器官病理学检查;腺泡细胞透射电镜观察;血清NO浓度测定;胰腺组织SOD和MDA测定。结果发现,雨蛙素联合脂多糖组血淀粉酶、NO浓度和胰腺湿重均增高,SOD活力降低,MDA含量升高,胰腺间质水肿、实质出血坏死、炎症细胞浸润,腺泡细胞受损严重,胰外多器官受到不同程度的损害;雨蛙素组胰腺无明显出血坏死,胰外器官正常;脂多糖组胰腺基本正常,胰外器官轻微炎症浸润。由本实验结果显示,雨蛙素联合脂多糖致小鼠重症急性胰腺炎模型具有人类重症急性胰腺炎的病理特征,为非创伤性,成模快速稳定,重复性好;脂多糖促使雨蛙素诱导的急性水肿型胰腺炎重症化的机理与自由基释放-清除机制和氧化-抗氧化机制紊乱有关。     

Fcγ receptor IIA and IIIB polymorphisms are associated with susceptibility to cerebral malaria

Human FcγRIIA and FcγRIIIB exhibit genetic polymorphisms, FcγRIIA-131H/R and FcγRIIIB-NA1/NA2, coding for different capacities for IgG binding and phagocytosis. Recently, FcγRIIA-131R was reported to be associated with protection against high-density Plasmodium falciparum infection in Kenya. Furthermore, FcγRIIIB-NA1/NA2 polymorphism was shown to influence FcγRIIA function in an allele-specific manner. In this study, we examined a possible association of FcγRIIA-131H/R and FcγRIIIB-NA1/NA2 polymorphisms with malaria severity in 107 cerebral malaria patients, 157 non-cerebral severe malaria patients, and 202 mild malaria controls living in northwest Thailand. This study reveals that, with the FcγRIIIB-NA2 allele, the FcγRIIA-131H/H genotype is associated with susceptibility to cerebral malaria (OR 1.85, 95% CI 1.14–3.01; P=0.012), although these polymorphisms are not individually involved in the disease severity. Our results suggest that FcγRIIA-131H/R and FcγRIIIB-NA1/NA2 polymorphisms have an interactive effect on host defense against malaria infection.     

Homogeneous repair of nuclear genes after experimental stroke

The repair of oxidative DNA lesions (ODLs) in the nucleus of ischemic cortical brain cells was examined following experimentally induced stroke by occluding the right middle cerebral artery and both common carotid arteries for 60-90 min followed by reperfusion in male long-Evans hooded rats. The control group consisted of sham-operated animals undergoing the same surgery without vessel occlusion. Using a gene-specific assay based upon the presence of Escherichia coli Fpg protein-sensitive sites, we noted that animals with stroke exhibited six and four ODLs per gene in the actin and DNA polymerase-beta genes, respectively. This was increased from one per four copies of each gene in the sham-operated control (p < 0.01). One half of the initial ODLs was repaired within 30 min, and 83% of them were repaired as early as 45 min of reperfusion. There was no further increase when gene repair was measured again at 2 h of reperfusion. The rates of active repair within 45 min of reperfusion were the same in these two genes (p = 0.103, ANOVA). BrdU (10 mg/kg) was administered via intraperitoneal injection at least one day before surgery. We observed that there was no significant incorporation of BrdU triphosphates into genomic DNA during active repair, but there were significant amounts of BrdU triphosphate in nuclear DNA after active repair. The result indicates that genomic repair of ODLs in the brain did not significantly incorporate BrdU, and the initiation of neurogenesis probably starts after the completion of repair in the brain.     

Changes in resting motor threshold of the tongue with normal aging and stroke

Aim of study: To examine the resting motor threshold of the tongue in healthy adults and stroke survivors.

Methods: Thirty-five healthy adults were classified into three groups: Group 1 (19–38?years; n?=?11), Group 2 (50–64?years; n?=?12) and Group 3 (66–78?years; n?=?12). Six chronic stroke survivors (mean age =59?years, SD?=?9.1?years) were recruited (Group 4). The resting motor thresholds (RMTs) of the tongue were measured and compared (i) among the four groups and (ii) between stroke survivors and age-matched healthy adults.

Results: Group 3 showed significantly higher RMTs than Group 1 (p?=?.001) and 2 (p =?0.007). Group 4 showed significantly higher RMTs than Group 1 (p =?.003) and 2 (p?=?.001). The RMTs of Group 3 and 4 were not significantly different (p =?.385). The RMT was positively correlated with age (r?=?0.534; p =?.001). Group 4 showed significantly higher RMTs than the age-matched controls (U?= 2.5, p?=?.009, r?=?0.77).

Conclusions: The resting motor threshold of the tongue is significantly increased in adults aged above 65 and in stroke survivors when compared with healthy adults. The findings suggested that the cortical excitability of the tongue deteriorates in the elderly and the stroke population.     

Effects of low-frequency repetitive transcranial magnetic stimulation on upper extremity motor recovery and functional outcomes in chronic stroke patients: A randomized controlled trial

Background: Repetitive transcranial magnetic stimulation (rTMS) was suggested as a preconditioning method that would increase brain plasticity and that it would be optimal to combine rTMS with intensive rehabilitation.

Objective: To assess the efficacy of inhibitory rTMS on upper extremity motor recovery and functional outcomes in chronic ischemic stroke patients.

Methods: In this randomized controlled trial, experimental group received low-frequency (LF) rTMS to the primary motor cortex of the unaffected side?+?physical therapy (PT), and control group received PT.

Results: No statistically significant difference was found in baseline demographical and clinical characteristics of the subjects including stroke severity or severity of paralysis prior to intervention. There were statistically significant improvements in all clinical outcome measures except for the Brunnstrom Recovery Stages. Fugl–Meyer Assessment, Box and Block test, motor and total scores of Functional Independence Measurement (FIM), and Functional Ambulation Scale (FAS) scores were significantly increased in both groups, however, these changes were significantly greater in the rTMS group except for FAS score. FIM cognitive scores and standardized mini-mental test scores were significantly increased and distal and hand Modified Ashworth Scale scores were significantly decreased only in the rTMS group (p?Conclusions: LF-rTMS can safely facilitate upper extremity motor recovery in patients with chronic ischemic stroke. TMS seems to be a promising treatment for motor, functional, and cognitive deficits in chronic stroke. Further studies with a larger number of patients with longer follow-up periods are needed to establish its effectiveness in stroke rehabilitation.     

The effect of a haptic biofeedback system on postural control in patients with stroke: An experimental pilot study

Background: Impaired balance in patients with hemiparesis caused by stroke is frequently related to deficits in the central integration of afferent inputs, and traditional rehabilitation reinforces excessive visual reliance by focusing on visual compensation.

Objective: The present study investigated whether a balance task involving a haptic biofeedback (BF) system, which provided supplementary vibrotactile sensory cues associated with center-of-foot-pressure displacement, improved postural control in patients with stroke.

Methods: Seventeen stroke patients were assigned to two groups: the Vibrotactile BF and Control groups. During the balance task (i.e., standing on a foam mat), participants in the Vibrotactile BF group tried to stabilize their postural sway while wearing the BF system around the pelvic girdle. In the Control group, participants performed an identical postural task without the BF system.

Results: Pre- and post-test measurements of postural control using a force plate revealed that the stability of bipedal posture in the Vibrotactile BF group was markedly improved compared with that in the Control group.

Conclusions: A balance task involving a vibrotactile BF system improved postural stability in patients with stroke immediately. This confirms the potential of a haptic-based BF system for balance training, both in routine clinical practice and in everyday life.     

Retracted: Intra‐arterial transplantation of human bone marrow mesenchymal stem cells (hBMMSCs) improves behavioral deficits and alters gene expression in rodent stroke model

Stroke is a multi‐factorial polygenic disease and is a major cause of death and adult disability. Administration of bone marrow stem cells protects ischemic rat brain by facilitating recovery of neurological functions. But the molecular mechanism of stem cells action and their effect on gene expression is not well explored. In this study, we have transplanted 1 × 10⁶ human bone marrow mesenchymal stem cells (hBMMSCs) in middle cerebral artery occluded (MCAo) adult male Wistar rats through intracarotid artery route at 24 h after surgery. Motor behavioral tests (rotarod and open field) were performed to assess the changes in motor functions at day 0 and day1, 4, 8 and 14. The expression of studied genes at mRNA and protein level was quantified by using Q‐PCR and western blotting, respectively. Further, we have assessed the methylation pattern of promoter of these genes by using methylation‐specific PCR. Data were analyzed statistically and correlated. A significant improvement in behavioral deficits was observed in stem cells treated group after 14th day post stroke. Significantly (p < 0.05) increased mRNA and protein levels of brain derived neurotrophic factor and ANP genes in hBMMSCs treated group along with decrease in methylation level at their promoter was observed. On the other hand, significantly decreased mRNA and protein level of TSP1 and WNK1 in hBMMSCs treated group was observed. In conclusion, hBMMSCs administration significantly improves the behavioral deficits by improving motor and locomotor coordination. The promoter of TSP1 and WNK1 genes was found to be hyper‐methylated in hBMMSCs group resulting in their decreased expression while the promoter of ANP and brain derived neurotrophic factor was found to be hypo‐methylated. This study might shed a light on how hBMMSCs affect the gene expression by modulating methylation status.