Cyclin-Dependent Kinases (CDK) and Their Role in Diseases Development-Review

Cyclin-dependent kinases (CDKs) are involved in many crucial processes, such as cell cycle and transcription, as well as communication, metabolism, and apoptosis. The kinases are organized in a pathway to ensure that, during cell division, each cell accurately replicates its DNA, and ensure its segregation equally between the two daughter cells. Deregulation of any of the stages of the cell cycle or transcription leads to apoptosis but, if uncorrected, can result in a series of diseases, such as cancer, neurodegenerative diseases (Alzheimer’s or Parkinson’s disease), and stroke. This review presents the current state of knowledge about the characteristics of cyclin-dependent kinases as potential pharmacological targets.

cGMP-dependent protein kinase I in vascular smooth muscle cells improves ischemic stroke outcome in mice

Recent works highlight the therapeutic potential of targeting cyclic guanosine monophosphate (cGMP)-dependent pathways in the context of brain ischemia/reperfusion injury (IRI). Although cGMP-dependent protein kinase I (cGKI) has emerged as a key mediator of the protective effects of nitric oxide (NO) and cGMP, the mechanisms by which cGKI attenuates IRI remain poorly understood. We used a novel, conditional cGKI knockout mouse model to study its role in cerebral IRI. We assessed neurological deficit, infarct volume, and cerebral perfusion in tamoxifen-inducible vascular smooth muscle cell-specific cGKI knockout mice and control animals. Stroke experiments revealed greater cerebral infarct volume in smooth muscle cell specific cGKI knockout mice (males: 96 ± 16 mm3; females: 93 ± 12 mm3, mean±SD) than in all control groups: wild type (males: 66 ± 19; females: 64 ± 14), cGKI control (males: 65 ± 18; females: 62 ± 14), cGKI control with tamoxifen (males: 70 ± 8; females: 68 ± 10). Our results identify, for the first time, a protective role of cGKI in vascular smooth muscle cells during ischemic stroke injury. Moreover, this protective effect of cGKI was found to be independent of gender and was mediated via improved reperfusion. These results suggest that cGKI in vascular smooth muscle cells should be targeted by therapies designed to protect brain tissue against ischemic stroke.

Association of CYP3A4*1G and CYP3A5*3 With the 1-year Outcome of Acute Ischemic Stroke in the Han Chinese Population

BACKGROUND AND PURPOSE

Previous studies have shown that common variants within CYP3A4 and CYP3A5 are associated with statin pharmacokinetics and the risk of cardiovascular disease. However, the association of variants in CYP3A4 and CYP3A5 with the prognosis of ischemic stroke remains undetermined. Therefore, we investigated this herein.

METHODS

Four hundred thirty-three consecutive patients with acute ischemic stroke were recruited. The outcome at the 1-year follow-up was assessed using the modified Rankin Scale (mRS). Two variants, CYP3A4*1G and CYP3A5*3, were genotyped by the improved Multiple Ligase Detection Reaction platform.

RESULTS

Binary logistic regression analysis showed that the CYP3A4*1G/*1G homozygote was associated with poor outcome at 1 year (mRS score ≥2) after adjustment for conventional factors in the additive model (odds ratio [OR] = 2.92; 95% confidence interval, 1.07-7.98; P = .037) and recessive model (OR = 3.37; 95% confidence interval, 1.26-9.04; P = .016). Subgroup analysis indicated that the CYP3A4*1G/*1G homozygote was associated with poor prognosis at 1 year among patients with stable high-intensity atorvastatin therapy (40-80 mg/d) after adjustment for conventional factors in the additive model (OR = 8.16; 95% confidence interval, 1.50-44.44; P = .015) and recessive model (OR = 9.06; 95% confidence interval, 1.72-47.64; P = .009). No significant association was identified between CYP3A5*3 and the 1-year outcome of patients with ischemic stroke.

CONCLUSIONS

Our study findings suggest that the CYP3A4*1G/CYP3A4*1G genotype may be associated with poor prognosis at 1 year after acute ischemic stroke in the Han Chinese population.

Investigation of the relationship between ischemic stroke and endothelial nitric oxide synthase gene polymorphisms [G894T, intron 4 VNTR and T786C]

Background/aim

We aimed to investigate the associations between endothelial nitric oxide synthase (eNOS) gene polymorphisms [G894T (rs1799983)], intron 4 (27-bpTR) variable number tandem repeat (VNTR) and T786C (rs2070744), and ischemic stroke in the Anatolian population.

Materials and methods

This case-control study included 112 patients with “stroke of undetermined etiology” and 160 controls. Real-time polymerase chain reaction (RT-PCR) analysis was used to analyze these polymorphisms. Between-group frequencies of alleles and genotypes were compared using binary logistic regression analysis.

Results

No significant difference was observed between the two groups in terms of the genotype and allele distributions of the eNOS G894T (rs1799983) polymorphism (P > 0.05). The a alleles and the 4b/a and 4a/a genotypes of the intron 4 (27-bpTR) VNTR polymorphism had significantly higher frequencies in the patient group than in the control group (OR: 2.715, P < 0.001; OR: 3.396, P < 0.001; OR: 10.631, P = 0.016, respectively). On the contrary, the TC genotype and C alleles of the T786C (rs2070744) polymorphism had a significantly lower frequency in the patient group than in the control group (OR: 0.244, P < 0.001, OR: 0.605, P = 0.006, respectively).

Conclusion

Our findings indicate that the eNOS G894T and T786C [rs2070744] polymorphisms are not associated with the risk of ischemic stroke, whereas the intron 4 [27-bpTR] VNTR may be a risk factor in the Anatolian population.

Visfatin Level and The Risk of Hypertension and Cerebrovascular Accident: A Systematic Review and Meta-Analysis

High blood pressure is related with increased cerebrovascular accident. High visfatin / NAMPT(nicotinamide phosphoribosyltransferase) plasma levels may promote vascular inflammation and atherosclerotic plaque destabilization and have been evaluated as a marker for identifying stages of essential hypertension. However, its role in the pathogenesis of hypertension and cerebrovascular accident (CVA) is still uncertain. In order to review and meta-analyze observational studies investigating visfatin concentration and the risk for hypertension or CVA, a systematic search of PubMed, ovid EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) until December 07, 2016 was performed. After data extraction and quality assessment, a meta-analysis was performed using RevMan 5.3 and STATA 14.0. A total of 1693 adults from 8 studies for hypertension (974 with hypertension) and 1696 adults from 7 CVA studies (957 with CVA) were enrolled in the current meta-analysis. Cochran's Q-statistic and I² test were applied to estimate the heterogeneity of the studies. The fixed-effects were used to compute the weighted mean difference in visfatin levels. Plasma visfatin concentration was much higher in hypertension and CVA patients than in healthy individuals. These evidences suggested the association of hypertension and CVA with higher plasma visfatin level.

CBS promoter hypermethylation increases the risk of hypertension and stroke

OBJECTIVES

Cystathionine β-synthase is a major enzyme in the metabolism of plasma homocysteine. Hyperhomocysteinemia is positively associated with hypertension and stroke. The present study was performed to examine the possible effects of Cystathionine β-synthase promoter methylation on the development of hypertension and stroke.

METHODS

Using quantitative methylation-specific PCR, we determined the Cystathionine β-synthase methylation levels in 218 healthy individuals and 132 and 243 age- and gender-matched stroke and hypertensive patients, respectively. The relative changes in Cystathionine β-synthase promoter methylation were analyzed using the 2-ΔΔCt method. The percent of the methylated reference of Cystathionine β-synthase was used to represent the Cystathionine β-synthase promoter methylation levels.

RESULTS

In this study, the Cystathionine β-synthase promoter methylation levels of hypertensive and stroke participants were both higher than that of the healthy individuals (median percentages of the methylated reference were 50.61%, 38.05% and 30.53%, respectively, all p<0.001). Multivariable analysis showed that Cystathionine β-synthase promoter hypermethylation increased the risk of hypertension [odds ratio, OR (95% confidence interval, CI)=1.035 (1.025-1.045)] and stroke [OR (95% CI)=1.015 (1.003-1.028)]. The area under the curve of Cystathionine β-synthase promoter methylation was 0.844 (95% CI: 0.796-0.892) in male patients with hypertension and 0.722 (95% CI: 0.653-0.799) in male patients with stroke.

CONCLUSION

Cystathionine β-synthase promoter hypermethylation increases the risk of hypertension and stroke, especially in male patients.

Effectiveness and safety of Injinoryung-San-Gagambang (Yinchen Wuling powder) decoction on stroke patients with elevated serum liver enzymes: Three case reports

RATIONALE

Injinoryung-San-Gagambang (IJORS) effectively improves hepatic dysfunction caused by polypharmacy in stroke patients.

PATIENT CONCERNS

We present 3 cases of hepatic dysfunction caused by polypharmacy, one of which was a 51-year-old man with cerebellum infarction and pneumonia as a complication of stroke. He took multiple medications because of baseline diseases. After recurrence of pneumonia, his laboratory tests showed abnormal aminotransferase levels. Another patient was an 81-year-old woman with cerebral infarction at the right-middle cerebral artery. She was also taking >5 medications. Her laboratory tests conducted on admission showed abnormally elevated aminotransferase levels. The last patient was 77-year-old man with cerebral infarction at the left-middle cerebral artery. He also had an abdominal aneurysm, a thoracic aortic aneurysm, and a myocardial infarction. After taking multiple medications including healthy functional foods, his laboratory tests showed abnormally elevated aminotransferase levels.

DIAGNOSIS

Diagnosis is conducted with the result of laboratory test including blood count, chemistry test.

INTERVENTIONS

All 3 patients received the same herbal treatment (IJORS decoction) for 1 to 3 weeks.

OUTCOMES

All 3 patients' abnormal serum aminotransferase level were significantly improved by IJORS decoction treatment while keeping other medicines.

LESSONS

IJORS can be considered as an effective treatment for hepatic dysfunction induced by numerous medications in stroke patients.

Prostaglandin E1-Mediated Collateral Recruitment Is Delayed in a Neonatal Rat Stroke Model

While arterial reflow after a stroke represents an important challenge for better outcomes, it is also very important that sudden recanalization does not produce local oxidative and nitrogen species, deleterious for the brain and more particularly the immature brain. Our objective was to determine whether a supply in prostaglandin (Pg) E1 (Alprostadil), via its action on arterial pressure, might progressively improve cerebral reperfusion in a neonatal stroke model. Arterial blood flow was measured using ultrasonography. Rate-limiting and Pg terminal synthesizing enzymes were evaluated using reverse-transcriptase polymerase chain reaction. Our data suggests that a supply in PgE1 might delay and improve the ipsilateral reperfusion by decreasing thromboxane A synthase-1 gene, the density of reactive astrocytes and lesion volume.

Administration of 5-methoxyindole-2-carboxylic acid that potentially targets mitochondrial dihydrolipoamide dehydrogenase confers cerebral preconditioning against ischemic stroke injury

The objective of this study was to investigate a possible role of mitochondrial dihydrolipoamide dehydrogenase (DLDH) as a chemical preconditioning target for neuroprotection against ischemic injury. We used 5-methoxyindole-2-carboxylic acid (MICA), a reportedly reversible DLDH inhibitor, as the preconditioning agent and administered MICA to rats mainly via dietary intake. Upon completion of 4 week's MICA treatment, rats underwent 1h transient ischemia and 24h reperfusion followed by tissue collection. Our results show that MICA protected the brain against ischemic stroke injury as the infarction volume of the brain from the MICA-treated group was significantly smaller than that from the control group. Data were then collected without or with stroke surgery following MICA feeding. It was found that in the absence of stroke following MICA feeding, DLDH activity was lower in the MICA treated group than in the control group, and this decreased activity could be partly due to DLDH protein sulfenation. Moreover, DLDH inhibition by MICA was also found to upregulate the expression of NAD(P)H-ubiquinone oxidoreductase 1(NQO1) via the Nrf2 signaling pathway. In the presence of stroke following MICA feeding, decreased DLDH activity and increased Nrf2 signaling were also observed along with increased NQO1 activity, decreased oxidative stress, decreased cell death, and increased mitochondrial ATP output. We also found that MICA had a delayed preconditioning effect four weeks post MICA treatment. Our study indicates that administration of MICA confers chemical preconditioning and neuroprotection against ischemic stroke injury.

G6PD plays a neuroprotective role in brain ischemia through promoting pentose phosphate pathway

TIGAR-regulated pentose phosphate pathway (PPP) plays a critical role in the neuronal survival during cerebral ischemia/reperfusion. Glucose-6-phosphate dehydrogenase (G6PD) is a rate-limiting enzyme in PPP and thus, we hypothesized that it plays an essential role in anti-oxidative defense through producing NADPH. The present study investigated the regulation and the role of G6PD in ischemia/reperfusion-induced neuronal injury with in vivo and in vitro models of ischemic stroke. The results showed that the levels of G6PD mRNA and protein were increased after ischemia/reperfusion. In vivo, lentivirus-mediated G6PD overexpression in mice markedly reduced neuronal damage after ischemia/reperfusion insult, while lentivirus-mediated G6PD knockdown exacerbated it. In vitro, overexpression of G6PD in cultured primary neurons decreased neuronal injury under oxygen and glucose deprivation/reoxygenation (OGD/R) condition, whereas knockdown of G6PD aggravated it. Overexpression of G6PD increased levels of NADPH and reduced form of glutathione (rGSH), and ameliorated ROS-induced macromolecular damage. On the contrary, knockdown of G6PD executed the opposite effects in mice and in primary neurons. Supplementation of exogenous NADPH alleviated the detrimental effects of G6PD knockdown, whereas further enhanced the beneficial effects of G6PD overexpression in ischemic injury. Therefore, our results suggest that G6PD protects ischemic brain injury through increasing PPP. Thus G6PD may be considered as potential therapeutic target for treatment of ischemic brain injury.

Aerobic exercise prevents rarefaction of pial collaterals and increased stroke severity that occur with aging

Variation in extent of the brain's collateral circulation is an important determinant of variation in the severity of stroke and efficacy of revascularization therapies. However, the number and diameter of pial collateral "arterioles" decrease with aging in associated with reduced eNOS and increased oxidative stress. We tested whether exercise reduces this aging-induced rarefaction. Twelve-month-old mice were randomized to sedentary or voluntary wheel-running. At 26 months' age, permanent MCA occlusion was followed 72 h later by determination of infarct volume and vascular casting after maximal dilation. The decline in collateral number and diameter and 2.4-fold increase in infarct volume evident in 26-versus 3-month-old sedentary mice were prevented by exercise-training. In contrast, number and diameter of the posterior communicating collateral "arteries" were unaffected by aging or exercise. Interestingly, diameter of the primary intracranial arteries increased with aging. Mechanistically, genetic overexpression of eNOS inhibited age-induced collateral rarefaction, and exercise increased eNOS and SOD2 and decreased the inflammatory marker NFkB assessed in hindlimb arteries. In conclusion, exercise prevented age-induced rarefaction of pial collaterals and reduced infarct volume. Aging also promoted outward remodeling of intracranial arteries. These effects were associated with increased eNOS and reduced markers of inflammation and aging in the vascular wall.

RETRACTED: Effects of rehabilitation training on apoptosis of nerve cells and the recovery of neural and motor functions in rats with ischemic stroke through the PI3K/Akt and Nrf2/ARE signaling pathways

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and Academic Committee of Jiangsu Normal University (ACJSNU). ACJSNU informed the journal that they were aware of PubPeer comments of data fabrication and manipulation in Fig 4A, Fig 5A, Fig 7A + C as detailed here [https://pubpeer.com/publications/D732FA0F313382B58DD725C25A8AB9#3]. ACJSNU launched an investigation and invited two independent referees to review the issues raised on PubPeer and they agreed the paper displays signs of scientific fraud. An investigation made by Tangshan People's Hospital, concluded there are no researchers called Jun-Chang Wu and Gao-Zhou Tang in the hospital. ACJSNU requested that the corresponding authors of the paper provide the original experimental records and data for verification. However, the authors have been unable to address the above concerns, and have stated that the data were obtained from a third party which was not disclosed in the article. The National Natural Science Foundation of China has also investigated this paper and others by the corresponding authors [https://www.nsfc.gov.cn/publish/portal0/tab442/info85495.htm]. The Editor-in-Chief therefore no longer has confidence in the data presented and the conclusions of the article.

Selective small-molecule inhibitors as chemical tools to define the roles of matrix metalloproteinases in disease

The focus of this article is to highlight novel inhibitors and current examples where the use of selective small-molecule inhibitors has been critical in defining the roles of matrix metalloproteinases (MMPs) in disease. Selective small-molecule inhibitors are surgical chemical tools that can inhibit the targeted enzyme; they are the method of choice to ascertain the roles of MMPs and complement studies with knockout animals. This strategy can identify targets for therapeutic development as exemplified by the use of selective small-molecule MMP inhibitors in diabetic wound healing, spinal cord injury, stroke, traumatic brain injury, cancer metastasis, and viral infection. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.

Association between the Matrix Metalloproteinase-9 rs3918242 Polymorphism and Ischemic Stroke Susceptibility: A Meta-Analysis

BACKGROUND

In recent years, dozens of case-control studies showed that matrix metalloproteinase (MMP)-9 rs3918242 variants were associated with ischemic stroke (IS) susceptibility. However, the conclusions of case-control studies that evaluated the relationship between MMP-9 rs3918242 variants and the risk of IS were still equivocal. Herein, we conducted a comprehensive meta-analysis to investigate the association between MMP-9 rs3918242 variants and the risk of IS.

METHODS

We searched 5 databases (PubMed, EMBASE, Google Scholar, Web of Science, and Chinese Biomedical Literature Database) to identify the eligible studies up to October of 2016. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to evaluate the association of MMP-9 rs3918242 variants with IS susceptibility under the allelic model (T versus C) and the dominant model (TT + CT versus CC).

RESULTS

A total of 14 studies with 3233 cases and 3123 controls were included in this meta-analysis. Our meta-analysis indicated that MMP-9 rs3918242 variants were associated with significantly increased risk of IS in overall populations (T versus C: OR = 1.43, 95% CI = 1.20-1.71, P < .001; TT + CT versus CC: OR = 1.39, 95% CI = 1.16-1.67, P < .001). Subgroup analysis based on ethnicity (Chinese and Caucasian) suggested that MMP-9 rs3918242 variants contributed to increase the risk of IS in Chinese population; However, no association was detected between MMP-9 rs3918242 variants and the risk of IS in Caucasian population.

CONCLUSION

Therefore, our meta-analysis suggested that MMP-9 rs3918242 variants (T allele, TT and CT genotypes) contributed to significantly increase the risk of IS in the Chinese population.

[ANALYSIS OF γ-GLUTAMYL CARBOXYLASE GENE rs2592551 POLYMORPHISM ASSOCIATION WITH ISCHEMIC ATHEROTHROMBOTIC STROKE]

The results of γ-glutamyl carboxylase gene rs2592551 polymorphism determining in 170 patients with ischemic atherothrombotic stroke and 124 subjects without acute cerebrovascular disease (control group) have been evaluated. Obtained results revealed that rs2592551 polymorphism was related to ischemic stroke in Ukrainian population. The risk for this disease in patients with T/T genotype was higher than in major C-allele carriers (odds ratio (OR) = 3.117; 95% confidence interval (CI) = 1.016-9.566; P = 0.047). After dividing patients into subgroups, formed by the presence of certain risk factors for atherosclerosis, similar association has been established for women and non-smokers. At the same time, the heterozygous genotype (C/T) in females had significantly protective effect against ischemic stroke development when compared to C/C and T/T genotypes (OR = 0.460; 95% CI 0.213-0.994; P = 0.048). Statistical significance of these results persisted even after adjustment for age, body mass index, smoking and hypertension.

Endothelial dysfunction and Protein kinase C activity development interrelation at ischemic injury of a brain

The ischemic stroke is the reason of high mortality and population disability worldwide and it is closely connected with endothelium dysfunction (ED). The endothelium carries out regulation of specific functions, generally the universal modulator - nitrogen oxide. A number of enzymes participates in a production of nitric oxide, but specific for an endothelium is endothelial NO synthase (eNOS), which violation of regulation is observed at an ischemic stroke. Significant role in activity of eNOS regulation plays protein kinase C (PKC). In this review the following processes were investigated: ED and nitric oxide interrelation at an ischemic stroke; some features of biological activity of nitric oxide depending on a place of synthesis and on time of ischemic damage; eNOS activity regulation by means of PKC; interrelation between ED and PKC activity at oxidative stress; the main alarm ways including activation of eNOS and PKC which regulate microvascular permeability and a tone of vessels of a brain. Being guided by the carried-out analysis of theoretical data, it should be noted that at development of ED the PKC hyperactivity is observed, therefore, the search of the substances possessing inhibiting influence on activity of PKC for treatment of the majority of cardiovascular diseases and an ischemic stroke has become particularly important and perspective.

The model homologue of the partially defective human 5,10-methylenetetrahydrofolate reductase, considered as a risk factor for stroke due to increased homocysteine level, can be protected and reactivated by heat shock proteins

The A222 V substitution in the human MTHFR gene product (5,10-methylenetetrahydrofolate reductase) is responsible for a decreased activity of this enzyme. This may cause an increased homocysteine level, considered as a risk factor for arteriosclerosis and stroke. The bacterial homologue of the human enzyme, MetF, has been found to be a useful model in genetic and biochemical studies. The similarity of Escherichia coli MetF and human MTHFR proteins is so high that particular mutations in the corresponding human gene can be reflected by the bacterial mutants. For example, the A222 V substitution in MTHFR (caused by the C667T substitution in the MTHFR gene) can be ascribed to the A117 V substitution in MetF. Here, it is reported that a temperature-sensitive MetF117 (A117 V) protein can be partially protected from a thermal inactivation by the heat shock proteins from the Hsp70/100 systems. Moreover, activity of the thermally denatured enzyme can be partially restored by the same heat shock proteins. High temperature protein G (HtpG) had no effect on MetF117 activity in both experimental systems. The presented results indicate that functions of heat shock proteins may be required for maintenance of the MetF117 function. This may have implications for the mechanisms of arteriosclerosis and stroke, especially in the light of previous findings that the A222 V MTHFR polymorphism may be a risk factor for stroke, as well as recently published results which demonstrated the increased levels of antibodies against heat shock proteins in stroke patients.

Regulation of Dipeptidyl Peptidase IV in the Post-stroke Rat Brain and In Vitro Ischemia: Implications for Chemokine-Mediated Neural Progenitor Cell Migration and Angiogenesis

Cerebral ischemia evokes abnormal release of proteases in the brain microenvironment that spatiotemporally impact angio-neurogenesis. Dipeptidyl peptidase IV (DPPIV), a cell surface and secreted protease, has been implicated in extracellular matrix remodeling by regulating cell adhesion, migration, and angiogenesis through modifying the functions of the major chemokine stromal-derived factor, SDF1. To elucidate the possible association of DPPIV in ischemic brain, we examined the expression of DPPIV in the post-stroke rat brain and under in vitro ischemia by oxygen glucose deprivation (OGD). We further investigated the effects of DPPIV on SDF1 mediated in vitro chemotactic and angiogenic functions. DPPIV protein and mRNA levels were significantly upregulated during repair phase in the ischemic cortex of the rat brain, specifically in neurons, astrocytes, and endothelial cells. In vitro exposure of Neuro-2a neuronal cells and rat brain endothelial cells to OGD resulted in upregulation of DPPIV. In vitro functional analysis showed that DPPIV decreases the SDF1-mediated angiogenic potential of rat brain endothelial cells and inhibits the migration of Neuro-2a and neural progenitor cells. Western blot analyses revealed decreased levels of phosphorylated ERK1/2 and AKT in the presence of DPPIV. DPPIV inhibitor restored the effects of SDF1. Proteome profile array screening further revealed that DPPIV decreases matrix metalloproteinase-9, a key downstream effector of ERK-AKT signaling pathways. Overall, delayed induction of DPPIV in response to ischemia/reperfusion suggests that DPPIV may play an important role in endogenous brain tissue remodeling and repair processes. This may be mediated through modulation of SDF1-mediated cell migration and angiogenesis.

Proteasomal activity in brain tissue following ischemic stroke in Wistar rats

Functional as well as structural reorganization of brain tissues takes place in the surrounding and remotes brain areas after focal ischemic lesions. In particular, reactive or regenerative processes have been described to occur in the infarction areas and the contralateral hemisphere. Experiments were performed on 63 rats, divided into 3 groups (each consisted of 21 animals): sham operated, short-term occlusion of the right middle cerebral artery (MCAO) group, and long-term MCAO group. We have studied changes in proteasome proteolysis during transient occlusion of the middle cerebral artery using method of Koizumi J., duration 2 and 60 min and made the comparison between changes in different types of proteasome activity and severity of ischemic injury and showed three types of decrease inproteolytic activity (trypsin-, chymotrypsin-like, peptidylglutamyl peptide-hydrolyzing) in the brain tissues. Chymotrypsin-like activity of ischemic areas of the brain for short-term MCAO decreased 4.1 times compared with controls (P > 0.05), for long-term MCAO decreased 5.8 times compared with controls (P < 0.05). Trypsin-like activity of ischemic areas of brain for short-term MCAO decreased 7.1 times compared with controls (P > 0.05), for long-term MCAO decreased 12.5 times compared with controls (P < 0.05). PGPH activity of ischemic areas for short-term MCAO decreased 8 times compared with controls (P > 0.05), for long-term MCAO decreased 2.8 times compared with controls (P < 0.05). The similar dynamics was observed also in the penumbra and the core zone of the brain at 6 h of reperfusion, in the long run there is no significant difference between the core and contralateral zones. Our results suggest that proteasome activity may play also a role in contralateral cortical plasticity occurring after focal cerebral ischemia.

Variants in neuronal nitric oxide synthase gene may contribute to increased ischemic stroke susceptibility in a Han Chinese population

Variants in neuronal NOS (nNOS) gene were associated with atherosclerosis and stroke susceptibility. We aimed to investigate the association between nNOS gene polymorphism and risk of ischemic stroke caused by small-artery occlusion (SAO) and large-artery atherosclerosis (LAA) in a Chinese population. We conducted a case-control study involving 381 ischemic stroke patients and 366 healthy subjects. Selected SNPs (rs1483757, rs2293050, and rs2139733) were genotyped and assessed; the association with the risk of ischemic stroke was analyzed. Furthermore, gender- and etiologic subtype-stratified analyses were also carried out to evaluate the association between nNOS polymorphisms and risk of ischemic stroke. No significant difference was observed between selected nNOS loci and risk of ischemic stroke in alleles or any genetic models in total study population, males or females, adjusted with age, drinking and smoking status. Rs2293050 and rs2139733 genotypes were associated with total cholesterol (rs2293050, P = 0.026; rs2139733, P = 0.040) and LDL (rs2293050, P = 0.031; rs2139733, P = 0.046) in females. A significant difference in allele distribution of rs2293050 (P = 0.040) and a marginally significant difference of rs2139733 (P = 0.061) in LAA-caused ischemic stroke cases and controls were observed in total population. No association between rs1483757 and ischemic stroke was found in this study. T allele of rs2293050 and A allele of rs2139733 in nNOS gene may contribute to increased susceptibility of LAA-caused ischemic stroke in Han Chinese.

Association between matrix metalloproteinase gene polymorphisms and development of ischemic stroke

We investigated the association between MMP2 rs243865, MMP3 rs3025058 and MMP9 rs3918242 polymorphisms and development of ischemic stroke in a Chinese population. Between January 2012 and May 2014, a total of 317 patients with ischemic stroke and 317 health control subjects were enrolled into our study. The MMP2 rs243865, MMP3 rs3025058 and MMP9 rs3918242 polymorphisms were analyzed using polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP). By multivariate logistic regression analysis, we found that individuals carrying with the CC genotype and the TC+CC genotype of MMP9 rs3918242 were associated with a significantly increased risk of ischemic stroke when compared with the TT genotype, and the ORs (95% CI) was 5.47 (2.64-12.38) and 1.55 (1.08-2.24), respectively. The TC+CC genotype of MMP9 rs3918242 was associated with an elevated risk of ischemic stroke in tobacco smokers, and the OR (95% CI) was 2.03 (1.11-3.74). In conclusion, our study suggests that MMP9 rs3918242 polymorphism is correlated with an elevated risk of ischemic stroke, and this gene polymorphism has interaction with tobacco smoking in the risk of ischemic stroke.

A combined pre-clinical meta-analysis and randomized confirmatory trial approach to improve data validity for therapeutic target validation

Biomedical research suffers from a dramatically poor translational success. For example, in ischemic stroke, a condition with a high medical need, over a thousand experimental drug targets were unsuccessful. Here, we adopt methods from clinical research for a late-stage pre-clinical meta-analysis (MA) and randomized confirmatory trial (pRCT) approach. A profound body of literature suggests NOX2 to be a major therapeutic target in stroke. Systematic review and MA of all available NOX2(-/y) studies revealed a positive publication bias and lack of statistical power to detect a relevant reduction in infarct size. A fully powered multi-center pRCT rejects NOX2 as a target to improve neurofunctional outcomes or achieve a translationally relevant infarct size reduction. Thus stringent statistical thresholds, reporting negative data and a MA-pRCT approach can ensure biomedical data validity and overcome risks of bias.

Involvement of microRNA214 and transcriptional regulation in reductions in mevalonate pyrophosphate decarboxylase mRNA levels in stroke-prone spontaneously hypertensive rat livers

Hypocholesterolemia has been epidemiologically identified as one of the causes of stroke (cerebral hemorrhage). We previously reported that lower protein levels of mevalonate pyrophosphate decarboxylase (MPD), which is responsible for reducing serum cholesterol levels in stroke-prone spontaneously hypertensive rats (SHRSP), in the liver were caused by a reduction in mRNA levels. However, the mechanism responsible for reducing MPD expression levels in the SHRSP liver remains unclear. Thus, we compared microRNA (miR)-214 combined with the 3'-untranslated region of MPD mRNA and heterogeneous nuclear RNA (hnRNA) between SHRSP and normotensive Wistar Kyoto rats (WKY). miR-214 levels in the liver were markedly higher in SHRSP than in WKY, whereas hnRNA levels were significantly lower. These results indicate that the upregulation of miR-214 and downregulation of MPD transcription in the liver both play a role in the development of hypocholesterolemia in SHRSP.

Potent and Selective Triazole-Based Inhibitors of the Hypoxia-Inducible Factor Prolyl-Hydroxylases with Activity in the Murine Brain

As part of the cellular adaptation to limiting oxygen availability in animals, the expression of a large set of genes is activated by the upregulation of the hypoxia-inducible transcription factors (HIFs). Therapeutic activation of the natural human hypoxic response can be achieved by the inhibition of the hypoxia sensors for the HIF system, i.e. the HIF prolyl-hydroxylases (PHDs). Here, we report studies on tricyclic triazole-containing compounds as potent and selective PHD inhibitors which compete with the 2-oxoglutarate co-substrate. One compound (IOX4) induces HIFα in cells and in wildtype mice with marked induction in the brain tissue, revealing that it is useful for studies aimed at validating the upregulation of HIF for treatment of cerebral diseases including stroke.

Association of two polymorphisms in the FADS1/FADS2 gene cluster and the risk of coronary artery disease and ischemic stroke

Little is known about the association of the FADS1/FADS2 SNPs and serum lipid levels and the risk of coronary artery disease (CAD) and ischemic stroke (IS) in the Chinese southern population. The present study aimed to determine such association in the Chinese southern population. A total of 1,669 unrelated subjects (CAD, 534; IS, 553; and healthy controls, 582) were recruited in the study. Genotypes of the FADS1 rs174546 SNP and the FADS2 rs174601 SNP were determined by the SNaPshot Multiplex Kit. The T allele and TT genotype frequencies of the two SNPs were predominant in our study population. The T alleles were associated with increased risk of CAD and IS. Correspondingly, the C alleles were associated with reduced risk of CAD and IS. Haplotype analyses showed that the haplotype of T-T (rs174546-rs174601) was associated with an increased risk for IS, and the haplotype of C-C (rs174546-rs174601) was associated with a reduced risk for CAD and IS. The two SNPs were likely to influence serum lipid levels. The T allele carriers of the two SNPs and rs174601 TT genotype were associated with decreased serum HDL-C and ApoAI levels in the patient groups and with an increased risk of CAD and IS. The present study suggests that the FADS1 rs174546 SNP and the FADS2 rs174601 SNP are associated with the risk of CAD and IS, and are likely to influence serum lipid levels. However, further functional studies are needed to clarify how the two SNPs actually affect serum lipid levels and the risk of CAD and IS.

Cytochrome 4A11 Genetic Polymorphisms Increase Susceptibility to Ischemic Stroke and Associate with Atherothrombotic Events After Stroke in Chinese

To evaluate the associations between four single-nucleotide polymorphisms (SNPs) in CYP4A11 and CYP4F2 and ischemic stroke (IS), and between these variants and atherothrombotic events after stroke. IS patients (n=396) and controls (n=378) were genotyped for two CYP4A11 SNPs (rs2269231 and rs9333025) and two CYP4F2 SNPs (rs2108622 and rs3093135). Patients were followed up for 12 months after the stroke for the atherothrombotic events. The frequency of the rs9333025 GG genotype was significantly higher in IS patients than in controls. Logistic regression analysis showed that the presence of rs9333025 GG in patients was associated with significantly higher risk of IS. Cox regression analysis revealed that the rs9333025 GG genotype was an independent risk factor for atherothrombotic events after stroke. The rs9333025 GG genotype increases patients' susceptibility to IS and is associated with high frequencies of atherothrombotic events in stroke patients.

Endothelial nitric oxide synthase gene intron 4 VNTR polymorphism in sickle cell disease: relation to vasculopathy and disease severity

BACKGROUND

Impaired NO bioavailability represents the central feature of endothelial dysfunction, and is a common denominator in the pathogenesis of vasculopathy in sickle cell disease (SCD). Evidence indicates the contribution of 4a allele of endothelial NO synthase (eNOS) gene to cardiac and renal diseases. We studied the 27-base pair tandem repeat polymorphism in intron 4 of eNOS gene in 51 patients with SCD compared with 55 healthy controls and evaluated its role in disease severity and hemolysis-associated complications.

PROCEDURE

Transfusion history, vaso-occlusive crisis, thrombotic events, urinary albumin excretion, and echocardiography were assessed. Analysis of eNOS intron 4 gene polymorphism was performed by polymerase chain reaction.

RESULTS

The distribution of eNOS alleles and genotypes was similar between patients with SCD and controls. Compared with bb genotype, the frequency of eNOS4a allele (aa and ab genotypes) was significantly higher in patients with elevated tricuspid regurgitant velocity (TRV) (P = 0.009), nephropathy (P = 0.006), or history of cerebral stroke (P = 0.029). Logistic regression analysis revealed that eNOS4a allele was an independent risk factor for elevated TRV (P < 0.001). Patients with SCD and eNOS4a allele had higher lactate dehydrogenase, serum ferritin, D-Dimer, and von Willebrand factor antigen (P < 0.05).

CONCLUSIONS

We suggest that eNOS intron 4 gene polymorphism is related to endothelial dysfunction and vasculopathy in SCD and could provide utility for prediction of increased susceptibility to vascular complications.

Effects of local hypothermia on neuronal cell apoptosis after intracerebral hemorrhage in rats

OBJECTIVES

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke that is characterized by significant morbidity and mortality. Thus far, there is no effective treatment option for spontaneous ICH. In this study, we aimed to investigate the effects of local hypothermia on brain injuries after ICH.

MEASUREMENTS

Bacterial collagenase was used to induce ICH stroke in male Wistar rats. We assessed the effects of normothermia and 4 hours of local hypothermia (~33.2°C) initiated 1 hour after collagenase infusion on the neurological outcomes and brain water content at 1 and 3 days after ICH. The pathological changes of neuronal ultrastructure were examined with transmission electron microscopy. Furthermore, the expression levels of apoptotic molecules and matrix metalloproteinases-9 (MMP-9) were determined using western blotting and immunohistochemical staining. Results :Local hypothermia tends to reduce neurological deficits compared with the normothermic group at day 3 after ICH. Transmission electron microscopy reveals that local hypothermia significantly improves the ultrastructural outcomes at 1 and 3 days after ICH. In addition, local hypothermia markedly reduces edema formation and the expression levels of MMP-9 and apoptotic signal.

CONCLUSION

These data suggest that local hypothermia induces a reduction in the brain edema and partly reduces neurological deficits along with marked inhibitory effects on MMP-9 and cell apoptosis after ICH.

Ischaemic accumulation of succinate controls reperfusion injury through mitochondrial ROS

Ischaemia-reperfusion injury occurs when the blood supply to an organ is disrupted and then restored, and underlies many disorders, notably heart attack and stroke. While reperfusion of ischaemic tissue is essential for survival, it also initiates oxidative damage, cell death and aberrant immune responses through the generation of mitochondrial reactive oxygen species (ROS). Although mitochondrial ROS production in ischaemia reperfusion is established, it has generally been considered a nonspecific response to reperfusion. Here we develop a comparative in vivo metabolomic analysis, and unexpectedly identify widely conserved metabolic pathways responsible for mitochondrial ROS production during ischaemia reperfusion. We show that selective accumulation of the citric acid cycle intermediate succinate is a universal metabolic signature of ischaemia in a range of tissues and is responsible for mitochondrial ROS production during reperfusion. Ischaemic succinate accumulation arises from reversal of succinate dehydrogenase, which in turn is driven by fumarate overflow from purine nucleotide breakdown and partial reversal of the malate/aspartate shuttle. After reperfusion, the accumulated succinate is rapidly re-oxidized by succinate dehydrogenase, driving extensive ROS generation by reverse electron transport at mitochondrial complex I. Decreasing ischaemic succinate accumulation by pharmacological inhibition is sufficient to ameliorate in vivo ischaemia-reperfusion injury in murine models of heart attack and stroke. Thus, we have identified a conserved metabolic response of tissues to ischaemia and reperfusion that unifies many hitherto unconnected aspects of ischaemia-reperfusion injury. Furthermore, these findings reveal a new pathway for metabolic control of ROS production in vivo, while demonstrating that inhibition of ischaemic succinate accumulation and its oxidation after subsequent reperfusion is a potential therapeutic target to decrease ischaemia-reperfusion injury in a range of pathologies.

Methylenetetrahydrofolate reductase gene A1298C polymorphism in pediatric stroke--case-control and family-based study

Moderate hyperhomocysteinemia is one of the risk factors of pediatric stroke. Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme, which regulates homocysteine metabolism, and some polymorphisms of gene encoding this enzyme are associated with a decreased activity of the enzyme. The aim of the study was to assess an association between the A1298C polymorphism and pediatric stroke. We also evaluated a possible synergistic effect of A1298C and C677T polymorphisms of this gene. The study group consisted of 88 children after ischemic stroke, 142 of their parents and 111 controls. The A1298C polymorphism was genotyped using the restriction fragment length polymorphism method. We used 2 study designs: a case-control model and a family-based association test. The Statistica 7.1 and EpiInfo 6 softwares were used in all analyses. We did not observe any statistically significant differences either in the transmission of the A allele in the family-based test or in the frequency of the A allele in the patients group compared with the controls. We also did not notice any significant additive or synergistic effects between the A1298C and C677T polymorphisms. An analysis of the results obtained in this study and a critical review of previously published studies indicate that the A1298C polymorphism of the MTHFR gene is not related to ischemic stroke in children.

Quantitative assessment of association between rs1801133 polymorphism and susceptibility to stroke

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism, which is essential for DNA synthesis and methylation. Genetic variations in the MTHFR gene seem to contribute to a decreased activity of MTHFR, ultimately confer increased susceptibility to stroke. To assess the association between this polymorphism and stroke risk, we conducted a comprehensive meta-analysis based on 73 eligible studies. A total of 73 studies, including 10,225 cases and 13,800 controls identified between 1999 and 2012, were selected through researching the PubMed, MEDLINE, EMBASE, Cochrane Library, Web of Science, and Chinese Biomedical Chinese National Knowledge Infrastructure and Literature database databases. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to assess the association. Overall, a significant elevated risk of stroke risk was associated with the rs1801133 polymorphism in all genetic models (homozygote model: OR 1.296, 95% CI 1.109-1.514; dominant model: OR 1.179, 95% CI 1.058-1.315; recessive model: OR 1.209, 95% CI 1.063-1.375; allele comparison model: OR 1.154, 95% CI 1.061-1.256). In the stratified analyses, significantly increased stroke risks were indicated among Asians in all genetic models (homozygote model: OR 1.726, 95% CI 1.314-2.267; dominant model: OR 1.535, 95% CI 1.282-1.838; recessive model: OR 1.452, 95% CI 1.160-1.818; allele comparison model: OR 1.403, 95% CI 1.211-1.626).The present meta-analysis suggests that rs1801133 polymorphism contributes to the risk of stroke, of note, in Asian populations.

Ischemic preconditioning provides neuroprotection by induction of AMP-activated protein kinase-dependent autophagy in a rat model of ischemic stroke

Accumulating evidence suggests that ischemic preconditioning (IPC) increases cerebral tolerance to the subsequent ischemic exposure. However, the underlying mechanisms are still not fully understood. In the present study, we tested the hypothesis that AMP-activated protein kinase (AMPK)-dependent autophagy contributed to the neuroprotection of IPC in rats with permanent cerebral ischemia. Male Sprague-Dawley rats were pretreated with vehicle, compound C (an AMPK inhibitor), or 3-methyladenine (3-MA, an autophagy inhibitor) and then were subjected to IPC induced by a 10-min middle cerebral artery occlusion. Afterward, the brain AMPK activity and autophagy biomarkers were measured. At 24 h after IPC, permanent cerebral ischemia was induced in these rats, and infarct volume, neurological deficits as well as cell apoptosis were evaluated 24 h later. We demonstrated that IPC activated AMPK and induced autophagy in the brain, which was accompanied by a reduction of infract volume, neurological deficits, and cell apoptosis after cerebral ischemia. Meanwhile, the IPC-induced autophagy was inhibited by compound C while the neuroprotection of IPC was abolished by compound C or 3-MA. These findings suggest that AMPK-mediated autophagy contributes to the neuroprotection of IPC, highlighting AMPK as a therapeutic target for stroke prevention and treatment.

Paraoxonase 1 in neurological disorders

Paroxonase 1 displays multiple physiological activities that position it as a putative player in the pathogenesis of neurological disorders. Here we reviewed the literature focusing on the role of paraoxonase 1 (PON1) as a factor in the risk of stroke and the major neurodegenerative diseases. PON1 activity is reduced in stroke patients, which significantly correlates inversely with carotid and cerebral atherosclerosis. The presence of the R allele of the Q192R PON1 polymorphism seems to potentiate this risk for stroke. PON1 exerts peroxidase activities that may be important in neurodegenerative disorders associated with oxidative stress. PON1 is also a key detoxifier of organophosphates and organophosphate exposure has been linked to the development of neurological disorders in which acetylcholine plays a significant role. In Parkinson's disease most of the studies suggest no participation of either L55M or the Q192R polymorphisms in its pathogenesis. However, many studies suggest that the MM55 PON1 genotype is associated with a higher risk for Parkinson's disease in individuals exposed to organophosphates. In Alzheimer's disease most studies have failed to find any association between PON1 polymorphisms and the development of the disease. Some studies show that PON1 activity is decreased in patients with Alzheimer's disease or other dementias, suggesting a possible protective role of PON1. No links between PON1 polymorphisms or activity have been found in other neurodegenerative diseases such as multiple sclerosis and amyotrophic lateral sclerosis. PON1 is a potential player in the pathogenesis of several neurological disorders. More research is warranted to ascertain the precise pathogenic links and the prognostic value of its measurement in neurological patients.

Mmp-9 inhibition: a therapeutic strategy in ischemic stroke

Ischemic stroke is a leading cause of disability worldwide. In cerebral ischemia there is an enhanced expression of matrix metallo-proteinase-9 (MMP-9), which has been associated with various complications including excitotoxicity, neuronal damage, apoptosis, blood-brain barrier (BBB) opening leading to cerebral edema, and hemorrhagic transformation. Moreover, the tissue plasminogen activator (tPA), which is the only US-FDA approved treatment of ischemic stroke, has a brief 3 to 4 h time window and it has been proposed that detrimental effects of tPA beyond the 3 h since the onset of stroke are derived from its ability to activate MMP-9 that in turn contributes to the breakdown of BBB. Therefore, the available literature suggests that MMP-9 inhibition can be of therapeutic importance in ischemic stroke. Hence, combination therapies of MMP-9 inhibitor along with tPA can be beneficial in ischemic stroke. In this review we will discuss the current status of various strategies which have shown neuroprotection and extension of thrombolytic window by directly or indirectly inhibiting MMP-9 activity. In the introductory part of the review, we briefly provide an overview on ischemic stroke, commonly used models of ischemic stroke and a role of MMP-9 in ischemia. In next part, the literature is organized as various approaches which have proven neuroprotective effects through direct or indirect decrease in MMP-9 activity, namely, using biotherapeutics, involving MMP-9 gene inhibition using viral vectors; using endogenous inhibitor of MMP-9, repurposing of old drugs such as minocycline, new chemical entities like DP-b99, and finally other approaches like therapeutic hypothermia.

HMG CoA reductase inhibitors (statins): use in stroke prevention and outcome after stroke

The use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) has been demonstrated to reduce the risk of primary and secondary ischemic stroke in patients with ischemic heart disease (relative risk reduction is 20-30%), confirmed by several prospective randomized placebo-controlled trials. At least one large prospective trial has also shown a similar benefit in patients without underlying ischemic heart disease. This is in contrast to an open-labeled trial conducted in the USA, which failed to demonstrate a significant benefit of statins in reducing stroke risk in hypertensive hyperlipidemic patients. It is less clear if treatment with statins before or after the onset of ischemic stroke also reduces its severity (improves outcome). Experimental animal studies where mice were pretreated with statins, demonstrated a reduced infarct size compared with untreated animals. Treatment with statins after stroke onset has also been demonstrated to enhance recovery without influencing infarct size (by increased angiogenesis, synaptogenesis and blood flow). A few clinical retrospective studies have demonstrated similar results. Prospective blinded placebo-controlled trials to test these findings are still lacking. This review discusses the various prospective trials in stroke prevention and available data on the effects of statins in improving outcome of established ischemic stroke. Alternate mechanisms of statins besides their lipid-lowering effect and relevance in reducing stroke risk and improving outcome are discussed. Finally, based on the present information, an evidence-based perspective about current and future use of statins in the short- and long-term management of ischemic stroke is presented.

Lipoprotein-associated phospholipase A2 is associated with atherosclerotic stroke risk: the Northern Manhattan Study

Background

Lipoprotein-associated phospholipase A2 (LpPLA2) levels are associated with stroke, though whether this extends to all populations and stroke subtypes is unknown.

Methods

Serum samples from stroke-free community participants in the Northern Manhattan Study were assayed for LpPLA2 mass and activity. Participants were followed annually for stroke. Cox-proportional-hazard models were fitted to estimate hazard-ratios and 95% confidence intervals (HR, 95% CI) for the association of LpPLA2 levels with ischemic stroke (IS), after adjusting for demographic and medical risk factors.

Results

Serum samples were available in 1946 participants, of whom 151 (7.8%) experienced a first IS during median follow-up 11 years. Mean age was 69 (SD 10), 35.6% were men, 20% non-Hispanic Whites, 22% non-Hispanic Blacks, and 55% Hispanics. LpPLA2 mass and activity levels were not associated with overall IS risk.

LpPLA2 mass but not activity levels were associated with strokes due to large artery atherosclerosis (LAA; adjusted HR per SD 1.55, 95% CI 1.17–2.04). There was a dose-response relationship with LAA (compared to first quartile, 2nd quartile HR = 1.43, 95% CI 0.23–8.64; 3rd quartile HR = 4.47, 95% CI 0.93–21.54; 4th quartile HR = 5.07, 95% CI 1.07–24.06). The associations between LpPLA2-mass and LAA-stroke risk differed by race-ethnicity (p = 0.01); LpPLA2-mass was associated with increased risk of LAA among non-Hispanic Whites (adjusted HR per SD 1.44, 95% CI 0.98–2.11), but not other race-ethnic groups.

Conclusion

LpPLA2-mass levels were associated with risk of atherosclerotic stroke among non-Hispanic White participants, but not in other race-ethnic groups in the cohort. Further study is needed to confirm these race-ethnic differences and the reasons for them.

Methylenetetrahydrofolate reductase (C677T and A1298C) polymorphisms, hyperhomocysteinemia, and ischemic stroke in Tunisian patients

OBJECTIVE

The present study evaluated the role of the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C gene polymorphisms and correlated these results with plasma homocysteine (Hcy) levels in Tunisian ischemic stroke (IS) patients.

METHODS

Overall, 84 patients with IS were included and compared with 100 healthy controls. The most common stroke risk factors were investigated. Fasting plasma Hcy levels were measured. Genotyping of the MTHFR C677T and A1298 polymorphisms was studied by polymerase chain reaction.

RESULTS

Aside from tobacco and alcohol use, the other studied factors were significant risk factors for IS. Mean plasma Hcy levels were significantly higher in IS patients than in controls (16.1 ± 8.28 μmol/L versus 8.76 ± 3.48 μmol/L, P < 10(-3)). Significant associations were found with both the MTHFR 677(CT + TT) and 1298 (AC + CC) genotypes in comparison with controls (P < 10(-3)). A significant synergistic interaction was also found with the double heterozygote MTHFR 677CT/1298AC (P < 10(-3)). Homocysteine levels were significantly higher in IS patients with the MTHFR C677T variant (CT and TT genotypes) (P < 10(-3)); however, the difference was not significant with the MTHFR A1298C variant (AC and CC genotypes) (P = .31).

CONCLUSION

The MTHFR C677T and A1298 polymorphisms (individually or in concert) and hyperhomocysteinemia represent important risk factors for IS. Elevated Hcy levels were found to be associated with the MTHFR C677T variant; however, no significant association was found with the MTHFR A1298C variant.

Hypoxia-inducible factor prolyl hydroxylases as targets for neuroprotection by "antioxidant" metal chelators: From ferroptosis to stroke

Neurologic conditions including stroke, Alzheimer disease, Parkinson disease, and Huntington disease are leading causes of death and long-term disability in the United States, and efforts to develop novel therapeutics for these conditions have historically had poor success in translating from bench to bedside. Hypoxia-inducible factor (HIF)-1α mediates a broad, evolutionarily conserved, endogenous adaptive program to hypoxia, and manipulation of components of the HIF pathway is neuroprotective in a number of human neurological diseases and experimental models. In this review, we discuss molecular components of one aspect of hypoxic adaptation in detail and provide perspective on which targets within this pathway seem to be ripest for preventing and repairing neurodegeneration. Further, we highlight the role of HIF prolyl hydroxylases as emerging targets for the salutary effects of metal chelators on ferroptosis in vitro as well in animal models of neurological diseases.

Induction of oxidative and nitrosative damage leads to cerebrovascular inflammation in an animal model of mild traumatic brain injury induced by primary blast

We investigate the hypothesis that oxidative damage of the cerebral vascular barrier interface (the blood-brain barrier, BBB) causes the development of mild traumatic brain injury (TBI) during a primary blast-wave spectrum. The underlying biochemical and cellular mechanisms of this vascular layer-structure injury are examined in a novel animal model of shock tube. We first established that low-frequency (123kPa) single or repeated shock wave causes BBB/brain injury through biochemical activation by an acute mechanical force that occurs 6-24h after the exposure. This biochemical damage of the cerebral vasculature is initiated by the induction of the free radical-generating enzymes NADPH oxidase 1 and inducible nitric oxide synthase. Induction of these enzymes by shock-wave exposure paralleled the signatures of oxidative and nitrosative damage (4-HNE/3-NT) and reduction of the BBB tight-junction (TJ) proteins occludin, claudin-5, and zonula occluden 1 in the brain microvessels. In parallel with TJ protein disruption, the perivascular unit was significantly diminished by single or repeated shock-wave exposure coinciding with the kinetic profile. Loosening of the vasculature and perivascular unit was mediated by oxidative stress-induced activation of matrix metalloproteinases and fluid channel aquaporin-4, promoting vascular fluid cavitation/edema, enhanced leakiness of the BBB, and progression of neuroinflammation. The BBB leakiness and neuroinflammation were functionally demonstrated in an in vivo model by enhanced permeativity of Evans blue and sodium fluorescein low-molecular-weight tracers and the infiltration of immune cells across the BBB. The detection of brain cell proteins neuron-specific enolase and S100β in the blood samples validated the neuroastroglial injury in shock-wave TBI. Our hypothesis that cerebral vascular injury occurs before the development of neurological disorders in mild TBI was further confirmed by the activation of caspase-3 and cell apoptosis mostly around the perivascular region. Thus, induction of oxidative stress and activation of matrix metalloproteinases by shock wave underlie the mechanisms of cerebral vascular BBB leakage and neuroinflammation.

Brain 3-Mercaptopyruvate Sulfurtransferase (3MST): Cellular Localization and Downregulation after Acute Stroke

3-Mercaptopyruvate sulfurtransferase (3MST) is an important enzyme for the synthesis of hydrogen sulfide (H2S) in the brain. We present here data that indicate an exclusively localization of 3MST in astrocytes. Regional distribution of 3MST activities is even and unremarkable. Following permanent middle cerebral artery occlusion (pMCAO), 3MST was down-regulated in both the cortex and striatum, but not in the corpus collosum. It appears that the down-regulation of astrocytic 3MST persisted in the presence of astrocytic proliferation due to gliosis. Our observations indicate that 3MST is probably not responsible for the increased production of H2S following pMCAO. Therefore, cystathionine β-synthase (CBS), the alternative H2S producing enzyme in the CNS, remains as a more likely potential therapeutic target than 3MST in the treatment of acute stroke through inhibition of H2S production.

Evaluation of serum oxidant/antioxidant balance in patients with acute stroke

OBJECTIVES

To investigate the alterations in the oxidant-antioxidant balance in patients with acute ischaemic stroke, and to locate any correlation between oxidant/antioxidant parameters and the National Institute of Health Stroke Scale.

METHODS

The case-control study was conducted at the Neurology Department of Dicle University Medical Faculty, Diyarbakir, Turkey, from June 2010 to June 2011. Blood samples were obtained from 53 patients with ischaemic stroke and 40 healthy controls without any history of ischaemic stroke or systemic disease. Venous blood was obtained within 24 hour after stroke onset. Serum malondialdehyde, total anti-oxidant capacity, paraoxanase and superoxide dismutase were measured. SPSS 11.5 used for statistical analysis.

RESULTS

There was no difference between the cases and the controls regarding age [64.5 +/- 15.8 and 66.3 +/- 13.9 respectively], gender [27 (51%) / 26 (49%), and 19 (48%) / 21 (52%) respectively], obesity [15(28.3%) and 13(37.5%), respectively], and hypertension [30 (56.6%) and 23 (57.5%), respectively]. The cases had higher concentrations of malondialdehyde (147.3 +/- 59.3 vs. 112.4 +/- 28.5 nmol/gr protein, p < 0.001), and superoxide dismutase (4.40 +/- 0.79 vs. 3.35 +/- 0.51, p < 0.001) compared to the controls. However, the cases had lower concentrations of paraoxanase (23.2 +/- 23.7 vs 64.7 +/- 52.6, p < 0.001), total anti-oxidant capacity (0.77 +/- 0.38 vs. 0.95 +/- 0.30, p < 0.015), and nitric oxide (10.8 +/- 7.1 vs. 17.5 +/- 2.4 micromol/gr protein, p < 0.001), compared to the controls. In the stroke group, a significant negative correlation was found between the National Institute of Health Stroke Scale and total anti-oxidant capacity activity (p < 0.021, r = -0.32).

CONCLUSION

The results support the hypothesis that sufficient anti-oxidant capacity has a beneficial effect on the clinical severity of acute ischaemic stroke.

Fluorometric immunocapture assay for the specific measurement of matrix metalloproteinase-9 activity in biological samples: application to brain and plasma from rats with ischemic stroke

BACKGROUND

Matrix metalloproteinases are important factors in the molecular mechanisms leading to neuronal injury in many neurological disorders. Matrix metalloproteinase (MMP)-9 is up-regulated after cerebral ischemia and neuroinflammation and is actively involved in blood-brain barrier disruption. Current methods of measuring MMP-9 activity, such as gelatin-substrate zymography, are unspecific and arduous. Here we developed an immunocapture assay with high efficiency, specificity, and sensitivity for quantifying endogenously active as well as total MMP-9 activity.

RESULTS

A fluorescence resonance energy transfer (FRET) peptide-based immunocapture assay was developed that enables the accurate assessment of total and active forms of MMP-9 in complex biological samples. The FRET assay demonstrated correct and efficient binding of MMP-9 to a mouse monoclonal MMP-9 antibody and high specificity of the immunocapture antibody for MMP-9. Total and active levels of MMP-9 were measured in rat brain homogenates, plasma, human HT-1080 conditioned media, and RBE4 endothelial cell lysates. The FRET immunocapture assay yielded highly similar results for total MMP-9 activity when compared to gelatin-substrate zymography.

CONCLUSIONS

We suggest that the new FRET peptide-based immunocapture assay is a viable replacement of zymography for sensitive and high throughput quantification of MMP-9 activity in biological samples.

Prognostic value of neuron specific enolase and IL-10 in ischemic stroke and its correlation with degree of neurological deficit

BACKGROUND

The blood-brain barrier is compromised in stroke patients. The release of neuro-biochemical protein markers, such as Neuron Specific Enolase (NSE) into the circulation may allow the pathophysiology and prognosis of patients with cerebrovascular diseases to be evaluated further.

METHOD

Present study aimed to investigate the predictive value of NSE and Interleukin-10 (IL-10) with respect to early neurobehavioral outcome which evaluated by National Institute of Health Stroke Scale (NIHSS). We investigated 100 patients of ischemic stroke and blood samples were taken within first 72 h of stroke onset. NSE and IL-10 were analyzed by commercially available ELISA kits. The neurological status was evaluated by a standardized NIHSS at the time of admission.

RESULTS

NSE was significantly increased (17.95±4.54 vs 7.48±1.51 {ng/ml} p≤0.05) and IL-10 significantly decreased (11.79±2.77 vs 15.72±2.69 {pg/ml} p≤0.05) in patients when compared with controls. NSE also significantly (r=0.8, p≤0.001) correlated with degree of neurological deficit but IL-10 level in serum did not show any significant correlation with NIHSS score at the time of admission.

CONCLUSIONS

Serum concentrations of NSE and IL-10 have a high predictive value for early neurobehavioral outcome after acute stroke.

Upregulation of protein phosphatase 2A and NR3A-pleiotropic effect of simvastatin on ischemic stroke rats

Ca(2+) influxes are regulated by the functional state of N-methyl-D-aspartate receptors (NMDARs). Dephosphorylation of NMDARs subunits decreases Ca(2+) influxes. NR3, a novel subunit of NMDARs, also decreases Ca(2+) influxes by forming new NMDARs with NR1 and NR2. It is meaningful to uncover whether protein phosphatase 2A (PP2A) and NR3A play a role in the protective effect of Simvastatin on ischemic stroke. In the present study, the Sprague-Dawley rats were pretreated with Simvastatin for 7 days before middle cerebral artery occlusion was performed to mimic ischemic stroke. The results showed that Simvastatin decreased brain ischemic infarct area significantly while increasing the expression levels of PP2A and NR3A, thus dephosphorylating the serine sites of NR1 (ser896 and ser897) along with increased enzymatic activities of PP2A. The protein levels of NR3A decreased as the enzymatic activities of PP2A were inhibited by okadaic acid. The results indicated that Simvastatin could protect the cerebrum from ischemic injury through a signaling mechanism involving elevated levels of PP2A and NR3A, and that PP2A might involve in the regulatory mechanism of NR3A expression.

Paraoxonase-1 Q192R polymorphism is not associated with clopidogrel response in Chinese stroke patients

It is well known that CYP2C19*2/*2 is associated with attenuated response to clopidogrel, but recent findings indicated that in white patients, paraoxonase-1 (PON1) 192Q/Q was a major determinant of clopidogrel efficacy. The objective of this research was to assess the impact of PON1 Q192R polymorphism on the maximum platelet aggregation (MPA) and the anti-platelet effect of clopidogrel in clopidogrel-treated Chinese stroke patients. The study recruited 183 eligible Chinese stroke patients treated with a loading dose of 300-mg clopidogrel and a 75-mg daily maintenance dose. CYP2C19*2 and PON1 Q192R were genotyped, a subcohort of 13 patients with CYP2C19 *2/*2 genotype was excluded. Finally 170 patients with CYP2C19*1/*1 (wild-type homozygotes, n = 87) or CYP2C19*1/*2 (mutant heterozygotes, n = 83) were enrolled in the study population. These patients were divided into three groups according to their PON1 Q192R genotype: wild-type homozygotes, PON1 192QQ, n = 17; mutant heterozygotes, PON1 192QR, n = 81; mutant homozygotes, PON1 192RR, n = 72. MPA was measured by light transmittance aggregometry (LTA) to assess platelet function after seven 75-mg maintenance doses of clopidogrel before discharge. In those patients who were carriers of 1 mutant allele (PON1 Q/R192), ADP-induced MPA were not significantly different compared with wild-type homozygous patients [30.5% (IQR, 17.5 to 49.1%) versus 25.0% (IQR, 10.0 to 52.5%), respectively; P = 0.910]. In addition, in the patients who were carriers of the 2 mutant allele (PON1 R/R192), MPA were also not significantly different from wild-type homozygous patients [29.2% (IQR, 15.0 to 43.4%) versus 25.0% (IQR, 10.0 to 52.5%), respectively; P = 0.717]. Results of a multivariable linear regression model demonstrated that PON1 192R allele carriage was not independently associated with ADP-induced MPA measurements (P = 0.408). PON1 Q192R polymorphism does not seem to exhibit any impact on MPA and clopidogrel response at all.

Mechanism of the sex difference in neuronal ischemic cell death

BACKGROUND

Stroke risk and outcome are different in men and women. We hypothesized that this is partly due to an inherent difference in susceptibility to ischemia between neurons from male vs. female brains. We tested whether neurons from male rodents are more susceptible to in-vitro ischemia than cells from females, and if this is related to increased expression of soluble epoxide hydrolase (sEH). sEH contributes to neuronal cell death by inactivating neuroprotective epoxyeicosatrienoic acids (EETs).

METHODS

Rodent cortical neurons were cultured, and exposed to oxygen-glucose deprivation (OGD); then cell death was measured. EETs levels were determined by LC-MS/MS. Expression of sEH-encoding ephx2 was determined by qRT-PCR. Western blotting, immunocytochemistry, and hydrolase activity assay assessed protein expression and activity.

RESULTS

Cell death after OGD was higher in neurons from males vs. females, which correlated with higher ephx2 mRNA and stronger sEH immunoreactivity. However, EETs levels were similar in both sexes and pharmacological inhibition of the hydrolase domain of sEH did not abolish the sex difference in cell death. Genetic knockout of sEH in mice abolished the sex difference observed in neurons isolated from these mice after OGD.

CONCLUSIONS

Cultured cortical neurons from females are more resistant to ischemia than neurons from males. Neurons from females have less sEH activity compared to neurons from males at baseline, although sEH levels were not measured after OGD. While pharmacological inhibition of the hydrolase domain of sEH does not affect cell death, knockout of the gene encoding sEH eradicates the sex difference seen in wild-type neurons, suggesting a role for further study of the lesser-known phosphatase domain of sEH and its role in sexual dimorphism in neuronal sensitivity to ischemia.

Plasma factor VII-activating protease antigen levels and activity are increased in ischemic stroke

BACKGROUND

Factor VII-activating protease (FSAP) is a recently discovered plasma protease with a role in the regulation of hemostasis and vascular remodeling processes. Higher levels and activity of FSAP have been reported in patients with deep vein thrombosis, but there are no data on plasma FSAP in ischemic stroke (IS).

OBJECTIVE

To investigate whether FSAP antigen levels and activity are associated with IS and/or etiologic subtypes of IS.

PATIENTS AND METHODS

To assess the potential association between FSAP and IS, plasma FSAP antigen levels and activity were measured in 600 consecutive IS patients and 600 population-based controls from the case-control study the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). Blood sampling was performed in the acute phase and 3 months after the index stroke. FSAP was also investigated at the genetic level by genotyping of 33 single-nucleotide polymorphisms.

RESULTS

Increased FSAP antigen level and activity, at both time-points, were independently associated with IS. Subtype analysis revealed similar associations for both FSAP measures, at both time-points, in all main IS subtypes. FSAP genotypes showed association with both FSAP plasma measurements, but not with IS.

CONCLUSIONS

Increased plasma FSAP antigen levels and activity were associated with IS and all main etiologic subtypes, suggesting a possible role for FSAP in the pathophysiology of IS, irrespective of the underlying etiology.

Changes in plasma matrix metalloproteinase-9 levels in patients with acute ischemic stroke

Matrix metalloproteinases (MMP) have been thought to be involved in stroke pathogenesis. MMP-9 contributes to tissue destruction. Our aim was to analyze the MMP-9 levels in blood within 24 hours of acute ischemic stroke onset to observe the role of MMP-9 in the pathogenesis of atherothrombotic stroke. In this study we investigated prospectively MMP-9 levels in serum from 106 patients (42 men and 64 women, mean age 71.52 +/- 6.32 years) with acute ischemic stroke in the middle cerebral artery area in the first 24 hours from the onset (mean duration 7.8 +/- 4.5 hours) as compared to 112 controls (48 men and 64 women, mean age 70.36 +/- 6.8 years). Serum samples were collected under sterile conditions and stored in aliquots at -70 degrees C until assay. Serum MMP-9 levels were determined by enzyme-linked immunosorbent assay (ELISA) in blood samples obtained on admission. Statistical analysis was performed by Mann-Whitney and Log-Likeliwood Ratio tests. All values reported are expressed as mean (x) +/- SD. Mean serum MMP-9 concentrations were higher in group with ischemic stroke 172 +/- 32.4 ng/mL, range 139.6-204.4 ng/mL vs. controls 57 +/- 9.6 ng/mL, range 47.4-66.6 ng/mL (95% CI, 3.17 to 14.18; p < 0.014). In conclusion, MMP-9 activity is associated with early acute ischemic stroke. The high levels of MMP-9 in acute ischemic stroke document the involvement of this enzyme in the regulation of inflammation in stroke.

Age-related changes in AMP-activated protein kinase after stroke

Adenosine monophosphate-activated protein kinase (AMPK) is an evolutionary conserved energy sensor sensitive to changes in cellular AMP/ATP ratio which is activated by phosphorylation (pAMPK). pAMPK levels decrease in peripheral tissues with age, but whether this also occurs in the aged brain, and how this contributes to the ability of the aged brain to cope with ischemic stress is unknown. This study investigated the activation of AMPK and the response to AMPK inhibition after induced stroke in both young and aged male mice. Baseline levels of phosphorylated AMPK were higher in aged brains compared to young mice. Stroke-induced a robust activation of AMPK in young mice, yet this response was muted in the aged brain. Young mice had larger infarct volumes compared with aged animals; however, more severe behavioral deficits and higher mortality were seen in aged mice after stroke. Inhibition of AMPK with Compound C decreased infarct size in young animals, but had no effect in aged mice. Compound C administration led to a reduction in brain ATP levels and induced hypothermia, which led to enhanced neuroprotection in young but not aged mice. This work demonstrates that aging increases baseline brain pAMPK levels; aged mice have a muted stroke-induced pAMPK response; and that AMPK inhibition and hypothermia are less efficacious neuroprotective agents in the aged brain. This has important translational relevance for the development of neuroprotective agents in preclinical models and our understanding of the enhanced metabolic stress experienced by the aged brain.

Variants within the nitric oxide synthase 1 gene are associated with stroke susceptibility

OBJECTIVE

Animal studies have allowed important insights into the role of the nitric oxide synthase (NOS) enzymes in atherosclerosis and hypertension, as well as in stroke. In this study we tested the hypothesis that the NOS1 and NOS3 genes, respectively encoding neuronal NOS (nNOS) and endothelial NOS (eNOS), influence stroke susceptibility and outcome after a stroke event.

METHODS

We conducted a case-control association study in 551 ischemic stroke patients and 530 controls to assess the role of NOS1 and NOS3 variants in stroke susceptibility. The same genes were tested for association with stroke outcome in a subset of 431 patients.

RESULTS

Four NOS1 single nucleotide polymorphisms (SNPs) (rs2293050, rs2139733, rs7308402 and rs1483757) and four haplotypes were significantly associated with stroke susceptibility after adjusting for demographic, clinical and life-style risk factors, and correcting for multiple testing using the false discovery rate (FDR) method (SNPs: 0.004<(uncorrected)P<0.007 and 0.036<FDR q<0.048; haplotypes: 0.001<(uncorrected)P<0.010 and 0.018<FDR q<0.032). NOS1 variants were not associated with stroke outcome. We did not find any evidence for a role of the NOS3 gene in stroke susceptibility or outcome.

CONCLUSION

Our results highlight NOS1 as a susceptibility factor for stroke, but do not corroborate previous NOS3 association findings with stroke risk. nNOS is known to play a major role in atherosclerosis development and in blood flow regulation, and it is plausible that its influence in stroke may be mediated through these two main clinical risk factors.