Current Neurovascular Research - Volume 7, Issue 1, 2010

Cerebral white matter lesions (WMLs), due to small vessel disease, can be regarded as an early “silent” sign of hypertensive cerebral end-organ damage. As haptoglobin (Hp) phenotype has earlier been associated with symptomatic vascular disease, we now examined the relationship between Hp phenotype and asymptomatic cerebral small vessel disease, manifested by deep and periventricular WMLs, in hypertensive patients. We determined Hp phenotype using starch gel electrophoresis in 152 hypertensive patients without symptomatic vascular disease. We found 26 (17.1%) Hp1-1, 89 (58.6%) Hp2-1 and 37 (24.3%) Hp2-2. Volumes of deep and periventricular WMLs were quantitatively measured on brain MR images. Patients were ranked in 5 categories according to ascending WMLs volumes. Compared to Hp2-2, Hp1-1 was associated with larger deep WMLs volumes when adjusted for age, gender, brain volume, 24-hour mean arterial pressure, duration of hypertension and previous antihypertensive treatment (ordinal regression analysis, OR 2.77, 95%CI 1.08-7.11, p=0.034). No association was found between Hp phenotype and periventricular WMLs. Hp1-1 phenotype correlates with the extent ofhypertensive deep white matter damage. One of the possibilities is that this is related to lower regenerating power against endothelial injury in Hp1-1 individuals.

Neural progenitors cells are capable of promoting neurogenesis after ischemic stroke in the adult mammalian brain; however the function of these cells and their fate is still not clear. Therefore the purpose of this study investigated the relationship between neural progenitors and reactive astrocytes after middle cerebral artery occlusion (MCAO). Brain infarction was induced by occlusion of a right cerebral artery in male Wistar rats. The fate of progenitor cells and the surrounding cells was investigated by immunochemical staining for nestin, vimentin and glial fibrillary acidic protein (GFAP) positive cells at several locations. Vimentin and nestin positive cells were observed in the ipsilateral subventricular zone (SVZ), striatum, and cortex at 3 and 7 days after MCAO, but those cells were not found at 28 days after ischemia. In contrast, reactive astrocyte positive cells increased following MCAO. These reactive astrocytes induced astrocytes differentiation of progenitor cells and formed dense astroglioses surrounding the ischemic lesion. Reactive astrocytes are thought to protect the penumbra during brain ischemia. We examined which brain cell expressed nestin and GFAP in the ipsilateral co-expression at 7 days after MCAO, especially at the core of injury. These results suggest that robust reactive astrocytes after MCAO were possibly differentiation from the induced nestin-positive cells after early ischemia.

Increasing evidence indicates that excessive iron in selective regions of the brain may be involved in the etiology of neurodegenerative disorders. Accordingly, increased levels of iron have been described in brain regions of patients in Parkinson's and Alzheimer's diseases. We have characterized neonatal iron loading in rodents as a novel experimental model that mimics the brain iron accumulation observed in patients with neurodegenerative diseases and produces severe cognitive impairment in the adulthood. In the present study we have investigated the involvement of the cholinergic system on iron-induced memory impairment. The effects of a single administration of the acetylcholinesterase (AChE) inhibitor galantamine or the muscarinic receptor agonist oxotremorine on iron-induced memory deficits in rats were examined. Male Wistar rats received vehicle or iron (10.0 mg/kg) orally at postnatal days 12 to 14. At the age of 2-3 months, animals were trained in a novel object recognition task. Iron-treated rats showed long-term impairments in recognition memory. The impairing effect was reversed by systemic administration of galantamine (1 mg/kg) immediately after training. In addition, iron-treated rats that received oxotremorine (0.5 mg/kg) showed enhanced memory retention. Rats given iron showed a decreased AChE activity in the striatum when compared to controls. The results suggest that, at least in part, iron-induced cognitive deficits are related to a dysfunction of cholinergic neural transmission in the brain. These findings might have implications for the development of novel therapeutic strategies aimed at ameliorating cognitive decline associated with neurodegenerative disorders.

The purpose of this study was to clarify the kinetics of nitric oxide (NO) induced by either endothelial NO synthase (eNOS) or neuronal NO synthase (nNOS) after transient global forebrain ischemia. We investigated NO production and ischemic changes to hippocampal CA1 neurons in eNOS knockout (-/-) mice and nNOS (-/-) mice during cerebral ischemia and reperfusion. NO production was continuously monitored by in vivo microdialysis. Global forebrain ischemia was produced by occlusion of both common carotid arteries for 10 minutes. Levels of nitrite (NO2-) and nitrate (NO3-), as NO metabolites, in dialysate were determined using the Griess reaction. Two hours after the start of reperfusion, animals were perfused with 4% paraformaldehyde. Hippocampal CA1 neurons were divided into three phases (severely ischemic, moderately ischemic, surviving), and the ratio of surviving neurons to degenerated neurons was calculated as the survival rate. The relative cerebral blood flow (rCBF) was significantly higher in nNOS (-/-) mice than in control mice after reperfusion. Levels of NO3- were significantly lower in eNOS (-/-) mice and nNOS (-/-) mice than in control mice during ischemia and reperfusion. NO3- levels were significantly lower in nNOS (-/-) mice than in eNOS (-/-) mice after the start of reperfusion. Survival rate tended to be higher in nNOS (-/-) mice than in control mice, but not significantly. These in vivo data suggest that NO production in the striatum after reperfusion is closely related to activities of both nNOS and eNOS, and is mainly related to nNOS following reperfusion. Theme: Disorders of the nervous system. Topic: Ischemia.

Neurotransmitters catechol and dopamine analogy levels are related to the systematic nerve activity. This assay was performed by using cyclic voltammetry (CV) and square wave (SW) stripping voltammetry, while optimization was performed by the carbon fiber microelectrode (CFME) with wire-type reference and counter electrodes. In the electrolyte solutions, the analytical parameters of catechol were as follows: 8.5 pH, -0.4 V anodic, 0.3 V cathodic, 15s deposition time, 15 Hz SW frequency, 25 mV SW amplitude and incremental potential of 4 mV, under optimal conditions, working ranges were 0-50 mgL-1 CV, 0.01-50 mgL-1 cathodic, and 1-13 mgL-1 anodic, the relative standard deviation was 0.02 %, n = 15 using 0.5 mgL-1 and the detection limit was 4.0 ugL-1. It can be used for in vivo direct analysis. Here, diagnostic applications were performed in the brain skeleton of living cells in real time. The developed techniques can be useful for nerve control and signal detections.

Subarachnoid hemorrhage (SAH) develops when extravasated arterial blood enters subarachnoid space and mixes with cerebrospinal fluid. As a result, many pathologies develop, including increase in brain-blood barrier (BBB) permeability and activation of peripheral leukocytes, that in turn augment immuno-inflammatory response, considered as the cause of numerous complications following SAH. In the study, we examined the role of one of the major cytokines, interleukin 1-beta (IL-1beta), in the BBB rupture and subsequent migration of leukocytes into central nervous system (CNS) after experimental SAH in adult rats. SAH was produced by injection of 150 uL of autologous arterial blood into cisterna magna. In 50% of animals, IL-1beta activity was inhibited by intracerebroventricular administration of anti-rat IL-1beta antibodies (SAH' groups). Control group consisted of sham-operated rats. Ninety minutes or 24 hrs following surgery, blood samples were taken, then animals were perfused transcardially and whole brains were collected. Three major populations of leukocytes present at brain stem and frontal part of the brain - granulocytes, monocytes/macrophages and lymphocytes - were labeled with appropriate antibodies. S-100B protein concentration in the serum, a marker of BBB permeability, was also measured. Neutralization of IL-1beta activity reduced elevated S-100B level and the number of leukocytes found within the CNS, however these changes were not uniformly significant among different subgroups. The results demonstrate an important role of IL-1beta in the BBB damage and leukocyte migration into the CNS subarachnoid hemorrhage.

The use of mesenchymal stem cells (MSCs) has been shown to be promising in chronic disorders such as diabetes, Alzheimer's dementia, Parkinson's disease, spinal cord injury and brain ischemia. Recent studies revealed that human tooth germs (hTG) contain MSCs which can be easily isolated, expanded and cryo-preserved. In this report, we isolated human tooth germ stem cells (hTGSCs) with MSC characteristics from third molar tooth germs, cryo-preserved them at -80°C for 6 months, and evaluated for their surface antigens, expression of pluri-potency associated genes, differentiation capacity, karyotype, and proliferation rate. These characteristics were compared to their non-frozen counterparts. In addition, neuro-protective effects of cryo-preserved cells on neuro-blastoma SH-SY5Y cells were also assessed after exposure to stress conditions induced by hydrogen-peroxide (oxidative stress) and paclitaxel (microtubule stabilizing mitotic inhibitor). After long term cryo-preservation hTGSCs expressed surface antigens CD29, CD73, CD90, CD105, and CD166, but not CD34, CD45 or CD133, which was typical for non-frozen hTGSCs. Cryo-preserved hTGSCs were able to differentiate into osteo-, adipo- and neuro-genic cells. They also showed normal karyotype after high number of population doublings and unchanged proliferation rate. On the other hand, cryo-preserved cells demonstrated a tendency for lower level of pluri-potency associated gene expression (nanog, oct4, sox2, klf4, c-myc) than non-frozen hTGSCs. hTGSCs conditioned media increased survival of SH-SY5Y cells exposed to oxidative stress or paclitaxel. These findings confirm that hTGSCs preserve their major characteristics and exert neuro-protection after long-term cryopreservation, suggesting that hTGSCs, harvested from young individuals and stored for possible use later as they grow old, might be employed in cellular therapy of age-related degenerative disorders.

Diabetes mellitus (DM) impacts a significant portion of the world's population and care for this disorder places an economic burden on the gross domestic product for any particular country. Furthermore, both Type 1 and Type 2 DM are becoming increasingly prevalent and there is increased incidence of impaired glucose tolerance in the young. The complications of DM are protean and can involve multiple systems throughout the body that are susceptible to the detrimental effects of oxidative stress and apoptotic cell injury. For these reasons, innovative strategies are necessary for the implementation of new treatments for DM that are generated through the further understanding of cellular pathways that govern the pathological consequences of DM. In particular, both the precursor for the coenzyme ß-nicotinamide adenine dinucleotide (NAD+), nicotinamide, and the growth factor erythropoietin offer novel platforms for drug discovery that involve cellular metabolic homeostasis and inflammatory cell control. Interestingly, these agents and their tightly associated pathways that consist of cell cycle regulation, protein kinase B, forkhead transcription factors, and Wnt signaling also function in a broader sense as biomarkers for disease onset and progression.