Many populations have low intakes of n-3 fatty acids, yet there is substantial evidence that the long chain n-3 fatty acid docosahexaenoic acid (DHA; 22:6n-3), found at high concentrations in the brain, is required for the proper development of the nervous system. However, less is known about requirements of long chain n-3 fatty acids for maintenance and function of the nervous system in later life. Several recent studies have reported that high amounts of long chain n-3 fatty acids reduce the extent of brain damage caused by cerebral ischemia in animals. However, whether or not a dietary deficiency of n-3 fatty acids increases the extent of injury when cerebral ischemia occurs has not been previously reported. The present studies, therefore, sought to determine if a diet deficient in n-3 fatty acids influences the extent of brain injury in the rat following cerebral ischemia. Male rats were fed an n-3 fatty acid adequate (control), an n-3 fatty acid deficient, or a high DHA diet for 5 weeks from weaning. Middle cerebral artery occlusion (MCAO) was induced and infarct volume was measured by 2,3,5,-triphenyltetrazolium chloride staining 24 hours after the procedure. Brain and platelet fatty acids were analyzed by gas liquid chromatography. DHA (22:6n-3) was 21-28% lower in brain phospholipids, and 17% lower in brain total fatty acids in the n-3 fatty acid deficient compared to control group, while 22:6n-3 was 12% higher in total brain fatty acids in the high DHA group than the control group. There was no significant difference in infarct volume (203, 220 and 218 mm³) among the control, n-3 fatty acid deficient, and high DHA groups, respectively. Platelet fatty acids and platelet aggregation were assessed to determine if these were influenced by the high DHA diet, and could possibly explain the observation of an apparent, but not statistically significant, higher number of rats with hemorrhages in the high DHA diet group. Platelet lipid arachidonic acid was not lower and platelet aggregation, assessed ex vivo using whole blood with a platelet function analyzer, was not longer in rats fed the high DHA compared to control or n-3 fatty acid deficient diets. In summary, dietary n-3 fatty acid deficiency did not increase the extent of brain injury following cerebral ischemia. The possibility that high dietary 22:6n-3 might increase susceptibility to cerebral hemorrhage will require further study.

Introdução: Após os resultados contundentes dos novos estudos de tratamento endovascular no acidente vascular cerebral isquêmico (AVCi), a detecção precoce dos casos de oclusão arterial proximal (OAP) se tornou uma medida fundamental na avaliação inicial de pacientes com isquemia cerebral no pronto-socorro. Todavia, esse diagnostico torna-se desafiador em centros de menor estrutura ou países em desenvolvimento, onde o acesso a neuroimagem vascular, como a angioressonância ou a angiotomografia, é restrito.Objetivos: Avaliar a acurácia da escala do NIHSS e da atenuação da artéria cerebral média na detecção de oclusões proximais no AVC agudo de circulação anterior. Formular um algoritmo de detecção dessas lesões baseado nesses parâmetros.Método: Foram avaliados retrospectivamente 178 pacientes consecutivos com diagnostico de AVCi de circulação anterior, através de registro prospectivo de pacientes admitidos em unidade de emergência de um hospital acadêmico terciário durante o ano de 2014. Os valores de NIHSS da admissão e de atenuação da artéria cerebral media (ACM) na tomografia de crânio não-contrastada (TCNC) foram coletados por dois examinadores cegos para os achados da neuroimagem vascular realizada na admissão. Foram destacados os valores de atenuação absoluta do vaso no lado sintomático (VA) e de atenuação relativa (rVA), através de uma razão entre o lado sintomático e sua área homóloga (imagem em espelho) no vaso contralateral. Modelos de curva ROC, estatísticas C e regressão logística foram usados para definir OAP, através da realização de um escore com os preditores de OAP. Resultados:Os valores de NIHSS e de atenuação da ACM se associaram com a presença de oclusão proximal,com uma área sob a curva de 0,88 (p < 0,001) e 0,76 (p < 0,001). Um NIHSS de 10 na admissão obteve uma sensibilidade e um valor preditivo negativo de 96,7% e 97,4%, respectivamente. Um VA >= 50 obteve uma especificidade e um valor preditivo positivode 93,9% e 81%. O OAP escore, que inclui estes preditores, demonstrou uma acurácia ainda maior na deteção de OAP, através de uma area sob a curva de 0,92 (p < 0,001). Conclusão:Os valores de NIHSS e de atenuação da ACM em TCNC estão relacionados com a presença de OAP na fase aguda do AVC.Escores baseados nesses parâmetros, como o OAP escore, podem ser usados de forma acurada na detecção de oclusão proximal. Mais estudos são necessários para validar o OAP escore em um cenário multicêntrico / Introduction: After the results of the new endovascular trials that demonstrated a robust effect of endovascular treatment for acute ischemic stroke (AIS), early detection of proximal artery occlusion (PAO) has become a fundamental task during the initial assessment of acute stroke patients at the emergency department. Nevertheless, an accurate identification of PAO may be particularly challenging in smaller hospitals and in developing countries, areas with restricted assess to vascular neuroimaging modalities such as CTA and MRA.Objectives: Evaluation of NIHSS and attenuation of middle cerebral artery (MCA) in detecting PAO. Perform an algorithm to identify these lesions. Method:We retrospectively evaluated 178 consecutive patients with AIS of the anterior circulation included in a prospective stroke registry of patients admitted to an academic tertiary emergency unit in Brazil during 2014 that had a NCCT and a CTA at admission. NIHSS scores and attenuation of middle cerebralartery (MCA) on NCCT were collected by two experienced investigators that were blind to the CT angiography findings. We used a ratio between two ROIs (rVA) that were drawn on NCCT blinded to CT angiography: (i) on the region of highest vessel attenuation ipsilateral to the involved hemisphere and (ii) mirror ROI on the corresponding vessel segment of the contralateral hemisphere. We used ROC curve analysis, C-statistics and logistic regression to predict PAO, establishing a predictor score (PAO score). Results: NIHSS and vessel attenuation values were highly associated with the PAO with an area under the curve (AUC) of 0.88 (p < 0,001) and 0.76 (p < 0,001), respectively. An NIHSS of 10 at admission had a sensitivity and negative predictive value of 96,7% and 97,4%, respectively. TheVA >= 50 had specificity and positive predictive value of 93,9% and 81%, respectively. The POA score showed an even higher accuracy for the presence of POA, with an AUC of 0.92 (p < 0,001). Conclusion:NIHSS and CMA vessel attenuation on NCCT valuesare associated to PAO in patients with AIS of the anterior circulation. Algorithms based on these findings could be used to detect PAO in this context. Further studies are necessary to validate the PAO score in a multicenter setting

Many populations have low intakes of n-3 fatty acids, yet there is substantial evidence that the long chain n-3 fatty acid docosahexaenoic acid (DHA; 22:6n-3), found at high concentrations in the brain, is required for the proper development of the nervous system. However, less is known about requirements of long chain n-3 fatty acids for maintenance and function of the nervous system in later life. Several recent studies have reported that high amounts of long chain n-3 fatty acids reduce the extent of brain damage caused by cerebral ischemia in animals. However, whether or not a dietary deficiency of n-3 fatty acids increases the extent of injury when cerebral ischemia occurs has not been previously reported. The present studies, therefore, sought to determine if a diet deficient in n-3 fatty acids influences the extent of brain injury in the rat following cerebral ischemia. Male rats were fed an n-3 fatty acid adequate (control), an n-3 fatty acid deficient, or a high DHA diet for 5 weeks from weaning. Middle cerebral artery occlusion (MCAO) was induced and infarct volume was measured by 2,3,5,-triphenyltetrazolium chloride staining 24 hours after the procedure. Brain and platelet fatty acids were analyzed by gas liquid chromatography. DHA (22:6n-3) was 21-28% lower in brain phospholipids, and 17% lower in brain total fatty acids in the n-3 fatty acid deficient compared to control group, while 22:6n-3 was 12% higher in total brain fatty acids in the high DHA group than the control group. There was no significant difference in infarct volume (203, 220 and 218 mm³) among the control, n-3 fatty acid deficient, and high DHA groups, respectively. Platelet fatty acids and platelet aggregation were assessed to determine if these were influenced by the high DHA diet, and could possibly explain the observation of an apparent, but not statistically significant, higher number of rats with hemorrhages in the high DHA diet group. Platelet lipid arachidonic acid was not lower and platelet aggregation, assessed ex vivo using whole blood with a platelet function analyzer, was not longer in rats fed the high DHA compared to control or n-3 fatty acid deficient diets. In summary, dietary n-3 fatty acid deficiency did not increase the extent of brain injury following cerebral ischemia. The possibility that high dietary 22:6n-3 might increase susceptibility to cerebral hemorrhage will require further study. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

The initial hours following an ischaemic event in the brain represent a critically important window in which therapeutic interventions to reduce neuronal damage and improve patient outcome can be made. Nevertheless, the dynamics of cerebral blood flow and oxygenation, as well as the local physiological changes, in the first few hours after reperfusion following ischaemic stroke are not well understood. In the first study, a remote filament approach was used to obtain multispectral imaging data before, during and after middle cerebral artery occlusion to investigate early changes in haemodynamic concentration of oxy-/deoxy-haemoglobin and total blood volume, in anaesthetised mice. We use immunohistochemistry to establish the extent of cortical injury and correlate the severity of damage with the change of oxygen perfusion during and after the ischaemic event. Increased numbers of platelets and activated microglia, expression of interleukin-1α, evidence of BBB breakdown and neuronal stress are all seen within the stroked hemisphere of MCAo mice and correlate with the severity of oxy-haemoglobin concentration deficit at experimental but not with the change in oxy-haemoglobin concentration during the acute stroke. In the second study, we used the same remote filament and optical imaging approach to investigate the effects of acute systemic inflammation on haemodynamics pre, during, and after induced cerebral ischaemia. We found that an acute systemic inflammatory challenge exacerbates oxy-haemoglobin deficit after 3 h of reperfusion following an ischaemic event. We investigated known pathophysiological markers to elucidate potential mechanisms that may contribute to this exacerbated oxygenation deficit and found hyper-coagulated platelets within the large and microvessels of the ipsilateral cortex. Our findings demonstrate that despite initial restoration of HbO2 supply after 30 min MCAo there is a delayed compromise that coincides with inflammatory processes that could be a future target for improved stroke outcome after thrombolysis. We also show that acute systemic inflammation exacerbates this oxy-haemoglobin deficit after an ischaemic challenge and increases pathophysiology.

Antibody-coated microprobes were inserted into the thoracic (T3-4) spinal cord in urethane-anesthetized Sprague-Dawley rats to detect the differences in the release of immunoreactive substance P-like (irSP) substances in response to differential activation of cardiac nociceptive sensory neurons (CNAN). CNAN were stimulated either by intrapericardial infusion of an inflammatory ischemic exudate solution (IES) containing algogenic substances (i.e., 10 mM each of adenosine, bradykinin, prostaglandin E2, and 5-hydroxytryptamine), or by transient occlusion of the left anterior descending coronary artery (CoAO). There was widespread basal release of irSP from the thoracic spinal cord. Stimulation of the CNAN by IES did not alter the pattern of release of irSP. Conversely, CoAO augmented the release of irSP from T3-4 spinal segments from laminae I-VII. This CoAO-induced irSP release was eliminated after thoracic dorsal rhizotomy. These results indicate that heterogeneous activation of cardiac afferents, as with focal coronary artery occlusion, represents an optimum input for activation of the cardiac neuronal hierarchy and for the resultant perception of angina. Excessive stimulation of cardiac nociceptive afferent neurons elicited during regional coronary artery occlusion involves the release of SP in the thoracic spinal cord and suggests that local spinal cord release of SP may be involved in the neural signaling of angina.

Previous studies have demonstrated that plasma resistin levels were increased in patients with acute ischemic stroke. However, the role of resistin after ischemic brain injury is still unclear. In this study, we investigated the protective effects of resistin on cerebral ischemia/reperfusion injury in a middle cerebral artery occlusion mouse model. We found that resistin (i.c.v.) significantly reduced infarct volume and improved neurological deficits after 45 min of ischemia and 24 h of reperfusion. Furthermore, our data demonstrate that intraperitoneal administration of resistin (10 µg/kg body weight) also had protective effects on infarct volume, indicating the crossing of resistin through the impaired BBB after ischemia injury. Resistin treatment reduced cleaved protein level of Poly(ADP-ribose)polymerase-1 (PARP-1), a marker of cellular apoptosis, showing the anti-apoptotic activity of resistin. Resistin increased the level of phosphorylated Akt after ischemic brain injury. The neuroprotective effect of resistin was partially reversed by a PI3K inhibitor wortmannin, demonstrating that the PI3K/Akt signal pathway is involved in the anti-apoptotic mechanisms of resistin. Finally, we found that resistin treatment improved neurological function recovery at 14 days after treatment, including balance ability and muscle strength. Given these findings, resistin may have therapeutic potential for the treatment of stroke.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Stroke is the third leading cause of death in South Africa, killing about 240 people a day and leaving survivors with residual disabilities. There is no clinically approved neuroprotective agent for stroke at the moment but the consumption of plant polyphenols has been suggested to offer neuroprotection against stroke and other neurodegenerative diseases. In this study, we investigated the effects of long term consumption of fermented rooibos herbal tea (FRHT) on ischemia reperfusion brain injury (I-RBI) in rats. Male adult Wistar rats were fed FRHT ad libitum for 7 weeks prior to the induction of ischemic injury by the transient bilateral occlusion of the common carotid arteries (BCCAO) for 20 minutes followed by 24 hours, 4 and 7 days of reperfusion respectively. Rats were then evaluated for neurologic deficits before sacrifice and brains harvested for assessment of brain oedema, blood-brain-barrier (BBB) integrity through Evans blue extravasation (EBE), immunohistochemical studies of apoptosis and lipid peroxidation. Oxygen radical antioxidant capacity and ferric reducing antioxidant power assays were also conducted to assess total antioxidant capacity after ischemia-reperfusion injury. Notably, the long term consumption of fermented rooibos herbal tea prevented brain oedema by reducing cerebral swelling induced by I-RBI. We also observed that fermented rooibos herbal tea offered neuroprotection against damage to the BBB and delayed neuronal death associated with BCCAO as fewer apoptotic cells were identified 7 days post BCCAO reperfusion. Significantly reduced levels of lipid peroxidation and increased levels of total antioxidant capacity were also observed in brain specimens of rats treated with FRHT. Rats treated with FRHT also showed improved neurologic outcomes when compared with the untreated animals. Our results show that FRHT has potent antioxidant and anti-inflammatory properties which can provide neuroprotective effects against neuronal cell loss, cerebral swelling, BBB disruption, lipid peroxidation and neurologic deficits following I-RBI. The use of FRHT is therefore highly recommended for patients with conditions that predispose them to stroke.

Spinal cord stimulation (SCS) represents an acceptable treatment modality for patients with chronic angina pectoris refractory to standard therapy, but its mechanism of action remains unclear. To develop an experimental paradigm to study this issue, ameroid (AM) constrictors were implanted around the left circumflex coronary artery (LCx) in canines. Six weeks later, unipolar electrograms were recorded from 191 sites in the LCx territory in the open-chest, anesthetized state under basal pacing at 150 beats/min. We investigated the effect of SCS on ST segment displacements induced in the collateral-dependent myocardium in response to two stressors: (i) transient bouts of rapid ventricular pacing (TRP: 240/min for 1 min) and (ii) angiotensin II administered to right atrial neurons via their coronary artery blood supply. ST segment responses to TRP consisted of ST segment elevation in central areas of the LCx territory and ST depression at more peripheral areas. Such responses were unchanged when TRP was applied under SCS. Shortening of repolarization intervals in the metabolically compromised myocardium in response to TRP was also unaffected by SCS. In contrast, ST segment responses to intracoronary angiotensin II, which consisted of increased ST elevation, were attenuated by SCS in 6/8 preparations. The modulator effects of SCS were greatest at sites at which the greatest responses to angiotensin II occurred in the absence of SCS. These data indicate that spinal cord stimulation may attenuate the deleterious effects that stressors exert on the myocardium with reduced coronary reserve, particularly stressors associated with chemical activation of the intrinsic cardiac nervous system.

The purpose of this study was to identify central neuronal sites activated by stimulation of cardiac ischemia-sensitive afferent neurons and determine whether electrical stimulation of left vagal afferent fibers modified the pattern of neuronal activation. Fos-like immunoreactivity (Fos-LI) was used as an index of neuronal activation in selected levels of cervical and thoracic spinal cord and brain stem. Adult Sprague-Dawley rats were anesthetized with urethane and underwent intrapericardial infusion of an "inflammatory exudate solution" (IES) containing algogenic substances that are released during ischemia (10 mM adenosine, bradykinin, prostaglandin E2, and 5-hydroxytryptamine) or occlusion of the left anterior descending coronary artery (CoAO) to activate cardiac ischemia-sensitive (nociceptive) afferent fibers. IES and CoAO increased Fos-LI above resting levels in dorsal horns in laminae I-V at C2 and T4 and in the caudal nucleus tractus solitarius. Dorsal rhizotomy virtually eliminated Fos-LI in the spinal cord as well as the brain stem. Neuromodulation of the ischemic signal by electrical stimulation of the central end of the left thoracic vagus excited neurons at the cervical and brain stem level but inhibited neurons at the thoracic spinal cord during IES or CoAO. These results suggest that stimulation of the left thoracic vagus excites descending inhibitory pathways. Inhibition at the thoracic spinal level that suppresses the ischemic (nociceptive) input signal may occur by a short-loop descending pathway via signals from cervical propriospinal circuits and/or a longer-loop descending pathway via signals from the nucleus tractus solitarius.

No description available.