Recurrent mild cerebral ischemia: enhanced brain injury following acute compared to subacute recurrence in the rat

Additional file 3. Histological assessments for Figure 3. Shown are the data for each animal at either 1d or 3d post a single mild ischemic insult. The H&E scores, the ED1 counts and the GFAP scores are presented

Better or worse food: Nutrition value of the prey fishes and the potential health implications for Indo-Pacific humpback dolphins

IntroductionOverfishing and climate change have combined to cause fishery stocks to decline and fish community composition to change, further threatening the predation and nutritional health of marine mammals.MethodsIn this study, we collected potential prey fishes catched by fishermen in six habitats of Indo-Pacific humpback dolphins and analyzed their proximate composition (moisture, water, fat and protein), the fatty acid composition and the amino acid composition to evaluate the possible health effect on humpback dolphins.ResultsThe results showed that the nutritional composition varied significantly with species and locations. Fishes in the families Sciaenidae and Engraulidae displayed richer fatty acid composition, while those in the family Clupeidae had the highest value of amino acid quality index. In Zhuhai, home to the largest Indo-Pacific humpback dolphin population, pelagic/neritic prey fishes possessed lower energy density, PUFA content, PUFA/SFA ratio, DHA content, and EAA content compared to demersal fish, suggesting nutritional stress when there is a dietary switch from demersal to pelagic/neritic fishes in Zhuhai population.DiscussionOur study provided a framework, with energy density and fatty acid composition as its most important indicator, for assessment of the marine top predators based on the nutritional composition of their prey fishes and revealed the potential threats. Data here is expected to facilitate the development of scientific programs for successful conservation of not only the Indo-Pacific humpback dolphins, but also other marine top predators, possibly through reconstructing their prey fish’s quantity and quality

Chronic treatment with Losartan and cerebral ischemic tolerance.

Clinical trials have suggested that Losartan has beneficial effects on preventing stroke beyond its antihypertensive properties. Although there is evidence for Losartan reducing ischemic damage following a highly localized type of stroke, its role in larger focal and global ischemic insults and the importance of blood pressure change are not known. We hypothesized that pre-treatment with Losartan would enhance the tolerance of the brain to both global and focal ischemia. Two weeks prior to ischemia, rats were administered either Losartan 50 mg/day in their drinking water or vehicle (water) alone. The neuroprotective effects of Losartan were assessed by either global ischemia using 10 minutes of four-vessel occlusion (4-VO) or 90 minutes of focal ischemia by distal middle cerebral artery occlusion. Seven days after 4-VO, histological assessment of cellular injury in the hippocampal CA1 region was performed. In addition, brain injury following transient MCAO was assessed by magnetic resonance imaging and histology. Losartan pretreatment reduced neuronal damage following global ischemia, as detected by 92 percent versus 46 percent neuronal cell death in CA1 region for Control and Losartan groups, respectively (p<0.001). Following transient ischemia, pre-treatment with Losartan resulted in a reduced infarct volume: measured as 41 percent \ub1 10 percent versus 26 percent \ub1 12 percent of the hemisphere in control and Losartan groups, respectively (p<0.04). These protective effects were observed in spite of 12\u201315 percent reductions in blood pressure in the Losartan treated group. Our results demonstrate that pre-treatment with Losartan enhances the tolerance of the brain to either global or focal ischemia and provides further evidence for Losartan as a treatment for stroke prevention.Peer reviewed: YesNRC publication: Ye

Experimental study on the effect of PVP, NaCl and EG on the methane hydrates formation and dissociation kinetics

Abstract The problem of hydrate plug, low efficiency of hydrate dissociation and short production time in hydrate exploitation processes have significantly hindered the commercial viability of gas hydrate extraction. This study investigated the inhibitory effects of ethylene glycol (EG), EG + polyvinyl pyrrolidone (PVP), and EG + PVP + sodium chloride (NaCl) on methane hydrate formation through experiment. The hydrate inhibitory performance is evaluated by using differential of pressure curve, the amount of hydrate, and pressure drop values, and the effects of different temperatures, pressures, inhibitors, and injection time on hydrate dissociation are further studied. The experiment results indicate that the rank of inhibitors combination in terms of effectiveness is 5%EG + 0.5 wt%PVP + 3 wt%Nacl > 10%EG + 1 wt%PVP > 30% EG. At low-temperature conditions, 30% EG exhibits good inhibition of hydrate synthesis but poor dissociation efficiency. As temperature increases, the hydrates dissociation rate with 30% EG also increases. For the combination inhibitor system of EG, PVP, and NaCl, PVP will reduce the dissociation efficiency of hydrates, while EG and Nacl will improve the hydrate dissociation performance. For low production pressure, it is found that 10% EG + 10% NaCl have a good promotion effect on hydrate dissociation, whereas under high production pressure, 20% EG + 10% NaCl is more effective. Furthermore, injecting the inhibitors earlier enhances the dissociation of hydrates more effectively

Training the brain to survive stroke.

Presently, little can be done to repair brain tissue after stroke damage. We hypothesized that the mammalian brain has an intrinsic capacity to adapt to low oxygen which would improve outcome from a reversible hypoxic/ischemic episode. Acclimation to chronic hypoxia causes increased capillarity and tissue oxygen levels which may improve the capacity to survive ischemia. Identification of these adaptations will lead to protocols which high risk groups could use to improve recovery and reduce costs.Rats were exposed to hypoxia (3 weeks living at ½ an atmosphere). After acclimation, capillary density was measured morphometrically and was increased by 30% in the cortex. Novel implantable oxygen sensors showed that partial pressure of oxygen in the brain was increased by 40% in the normal cortex. Infarcts were induced in brain with 1 h reversible middle cerebral artery occlusions. After ischemia (48 h) behavioural scores were improved and T2 weighted MRI lesion volumes were reduced by 52% in acclimated groups. There was a reduction in inflammation indicated by reduced lymphocytes (by 27-33%), and ED1 positive cells (by 35-45%).It is possible to stimulate a natural adaptive mechanism in the brain which will reduce damage and improve outcome for a given ischemic event. Since these adaptations occur after factors such as HIF-1α have returned to baseline, protection is likely related more to morphological changes such as angiogenesis. Such pre-conditioning, perhaps with exercise or pharmaceuticals, would not necessarily reduce the incidence of stroke, but the severity of damage could be reduced by 50%

MOESM4 of Recurrent mild cerebral ischemia: enhanced brain injury following acute compared to subacute recurrence in the rat

Additional file 4. Histological assessments for Figure 4. Shown are the data for each animal at either 1d or 3d post a single mild ischemic insult. Positive staining counts for TNF, Iba1 and EBA in addition to the Lectin scores and IgG gray level measures are presented