Effect of ischemic preconditioning on cerebral blood flow after subsequent lethal ischemia in gerbils

Ischemic tolerance, the phenomenon where a sublethal ischemic preconditioning protects the brain against a subsequent lethal ischemia, has been widely studied. Studies have been done on cerebral blood flow levels prior to the lethal ischemia, but the hemodynamic pattern after global ischemia with ischemic preconditioning has not been reported. Sequential changes in regional cerebral blood flow (rCBF) in gerbil hippocampus after 5 min global ischemia with or without 2 min ischemic preconditioning were studied to determine if ischemic preconditioning affects rCBF. Four different treatments were given: (1) sham-operated, (2) 2 min ischemia, (3) non-preconditioned, and (4) preconditioned. Groups (1) and (2) (both groups n = 5) were given a 24-h recovery period and the rCBF was measured for baseline values. 24 h after sham-operation (3) and 2 min ischemia (4), gerbils were subjected to 5 min ischemia followed by 1 h, 6 h, 1-day or 7-day reperfusion periods (all groups n = 5). Although no regional difference was observed in the recovery pattern of rCBF, the values of rCBF were significantly higher in the preconditioned group throughout whole brain regions including hippocampus. These results indicate that ischemic preconditioning facilitated the recovery of rCBF after 5 min global ischemia. It needs further study to determine whether the protecting effects of preconditioning relate to the early recovery of rCBF or not. However, our results could be interpreted that the early recovery of rCBF may lead to benefits for cell survival in the CA1 neuron, probably facilitating other protecting mechanisms.     

Neuropathy Target Esterase: Rates of Turnover In Vivo Following Covalent Inhibition with Phenyl Di-n-Pentylphosphinate

Phenyl di-n-pentylphosphinate is a reasonably stable easily synthesized inhibitor of neuropathy target esterase (NTE) with low anticholinesterase activity. Like phenylmethylsulphonyl fluoride it protects hens against neuropathic effects of compounds such as diisopropylphosphorofluoridate. At intervals up to 15 days after dosing hens (10 mg/kg s.c. to inhibit 90% NTE) assays were made of catalytically active and of phosphinylated NTE in autopsy tissue. The sum of these components was always within the range of catalytic activity in undosed controls. However, the half-life of reappearance of active NTE was 2.07 days +/- 0.13 (SD, n = 6) for brain and 3.62 days +/- 0.23 (SD, n = 6) for spinal cord--shorter than after dosing with phenylmethylsulphonyl fluoride. It is proposed that: (1) The physiological turnover mechanism cannot distinguish between catalytically active and di-n-pentylphosphinylated NTE although initiation of organophosphate-induced delayed polyneuropathy might involve recognition of aged di-alkyl-phosphorylated NTE as "foreign". (2) The short half-lives indicate a slow spontaneous dephosphinylation of inhibited NTE occurs in vivo as well as de novo synthesis. The difference in half-lives for brain and spinal cord NTE may be due to different rates of synthesis de novo or (more likely) to different rates of spontaneous reactivation of the inhibited NTE in the two tissues.     

Ships in Distress,Environmental Threats to Coastal States,and Places of Refuge: New Directions for an Ancien Regime ?

Places of refuge for ships in distress is a topic before the International Maritime Organization as a result of several recent well-publicized refusals by maritime authorities of coastal states to allow such ships to enter sheltered waters within national jurisdiction. The traditional right of refuge of the crew, ship, and cargo is pitted against threat perceptions held by coastal states resulting in a "not in my backyard" syndrome. Instances of modern state practice seem to restrict the right of refuge to a purely humanitarian dimension. There is a need to reevaluate the right of refuge and to establish a system of places of refuge on the basis of regional cooperation to counter the potential threat of stricken ships that are unable to effect necessary repairs in sheltered areas within national jurisdiction.     

Factors underpinning Iranian farmers’ intention to conserve biodiversity at the farm level

The depletion of biodiversity is a major environmental challenge of the present time, with the agricultural sector being a significant contributor to the loss. Therefore, farmers' decisions and practices are pivotal in safeguarding biodiversity at the farm level. Accordingly, this study aimed to unravel the key factors influencing farmers' intention to conserve biodiversity (ICB), and in doing so, it adopted the protection motivation theory (PMT) as the theoretical framework. The study's statistical population comprised 412 farmers residing in Bavi County in the southwestern region of Iran. The research employed a questionnaire as the data collection instrument, and the research hypotheses were tested using structural equation modeling (SEM). The findings indicated that the respondents held a perception of high costs associated with implementing biodiversity conservation behaviors. They believed that such measures would not be easy to implement, and they would incur both monetary and non-monetary costs. Furthermore, the findings of the study revealed that the variables of SE and ICB among the studied farmers were lower than the theoretical median of 3, indicating that farmers may not have a strong desire and self-efficacy to engage in biodiversity conservation practices. Through the application of SEM, the study determined that the PMT accounts for 65.2% of farmers’ ICB. Additionally, perceived severity and self-efficacy were found to have the strongest effects on farmers’ ICB (as the first and second determinants), highlighting the importance of these variables in predicting farmers’ conservation behaviors. Overall, it can be concluded that these results have significant implications for policymakers in the agricultural sector, providing valuable insights into how to promote biodiversity conservation practices among farmers.     

Changes in composition and structure of Vitex shrubland in northern China in relation to human disturbance

Vegetation and biomass in six plots, each with five quadrats, in Vitex shrubland in northern China were related to type and degree of human disturbance. Canonical correspondence analysis of the vegetation and environmental data showed two lines of variation, the first one highly correlated with the degree of disturbance, but the second one appearing within the disturbed plots cannot yet be fully explained. Changes in life-form spectrum were small, but the geographical spectrum changed under heavy disturbance towards a higher proportion of tropical, subtropical and cosmopolitan species. The number of shrub species also decreased noticeably. The above-ground biomass of both Vitex and the accompanying species and the total above-ground biomass of the shrubland was negatively correlated with the intensity of disturbance. The root/stem biomass ratio in Vitex reaches values of over 5 in disturbed plots, but only between 1 and 2 in the protected plots.     

Clerocidin-mediated DNA footprinting discriminates among different G-quadruplex conformations and detects tetraplex folding in a duplex environment

Background

G-quadruplexes are polymorphic non-canonical nucleic acid conformations involved both in physiological and pathological processes. Given the high degree of folding heterogeneity and comparable conformational stabilities, different G-quadruplex forms can occur simultaneously, hence rendering the use of basic instrumental methods for structure determination, like X-ray diffraction or NMR, hardly useful. Footprinting techniques represent valuable and relatively rapid alternative to characterize DNA folding. The natural diterpenoid clerocidin is an alkylating agent that specifically reacts at single-stranded DNA regions, with different mechanisms depending on the exposed nucleotide.

Methods

Clerocidin was used to footprint G-quadruplex structures formed by telomeric and oncogene promoter sequences (c-myc, bcl-2, c-kit2), and by the thrombin binding aptamer.

Results

The easy modulability of CL reactivity towards DNA bases permitted to discriminate fully and partially protected sites, highlights stretched portions of the G-quadruplex conformation, and discriminate among topologies adopted by one sequence in different environmental conditions. Importantly, CL displayed the unique property to allow detection of G-quadruplex folding within a duplex context.

Conclusions

CL is a finely performing new tool to unveil G-quadruplex arrangements in DNA sequences under genomically relevant conditions.

General significance

Nucleic acid G-quadruplex structures are an emerging research field because of the recent indication of their involvement in a series of key biological functions, in particular in regulation of proliferation-associated gene expression. The use of clerocidin as footprinting agent to identify G-quadruplex structures under genomically relevant conditions may allow detection of new G-quadruplex-based regulatory regions.     

Biological insights from hydrogen exchange mass spectrometry

Over the past two decades, hydrogen exchange mass spectrometry (HXMS) has achieved the status of a widespread and routine approach in the structural biology toolbox. The ability of hydrogen exchange to detect a range of protein dynamics coupled with the accessibility of mass spectrometry to mixtures and large complexes at low concentrations result in an unmatched tool for investigating proteins challenging to many other structural techniques. Recent advances in methodology and data analysis are helping HXMS deliver on its potential to uncover the connection between conformation, dynamics and the biological function of proteins and complexes. This review provides a brief overview of the HXMS method and focuses on four recent reports to highlight applications that monitor structure and dynamics of proteins and complexes, track protein folding, and map the thermodynamics and kinetics of protein unfolding at equilibrium. These case studies illustrate typical data, analysis and results for each application and demonstrate a range of biological systems for which the interpretation of HXMS in terms of structure and conformational parameters provides unique insights into function. This article is part of a Special Issue entitled: Mass spectrometry in structural biology.     

三七皂苷R1对大鼠缺血心肌VEGF、bFGF的影响

目的:探讨三七皂苷R1对大鼠缺血心肌VEGF、bFGF的影响。方法:选择雄性Wistar大鼠39只,建立心肌梗死(AMI)模型,术后24h存活大鼠随机分为药物组(n=13)、对照组(n=13),另设假手术组(n=8)。药物组给予三七皂苷R1水溶液(2.5 mg·kg-1·d-1)腹腔注射、对照组及假手术组给予等体积生理盐水腹腔注射,用药4周。于实验终点处死大鼠,心肌组织取材,Ⅷ因子染色计数微血管数(MVC)及微血管密度(MVD),免疫组织化学法观察缺血心肌VEGF、bFGF蛋白的表达。结果:药物组及对照组MVC、MVD均高于假手术组,且药物组高于对照组(P0.05);大鼠缺血心肌药物组及对照组VEGF、bFGF蛋白表达均高于假手术组(P0.05),且药物组高于对照组(P0.05)。结论:三七皂苷R1促进大鼠缺血心肌血管再生同时可上调缺血心肌VEGF、bFGF蛋白水平。     

The case in international law for Canada's extension of fisheries jurisdiction beyond 200 miles

In March 1995, Canadian fisheries authorities boarded and arrested the Spanish fishing vessel, Estai, outside the Canadian 200‐mile zone on the Grand Banks, an event that served to focus world attention on a dispute that had its origins in the failure of the 1982 United Nations Convention on the Law of the Sea to implement an effective conservation and management regime for fish stocks on the high seas, particularly with respect to fish stocks that straddle coastal states’ exclusive economic zones. This article examines the origins of the dispute, including the allegations relating to overfishing of North Atlantic Fisheries Organization‐recommended quotas, the background to the vessel's arrest, and the subsequent confrontation that occurred, both at diplomatic levels and on the high seas, between Canada and the European Union. An analysis is made of the case in international law for Canada's extension of jurisdiction beyond 200 miles pursuant to the provisions of Section 5 of the Coastal Fisheries Protection Act. Finally, the article examines the implications of the recently concluded Agreement on the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks for disputes of the kind that arose in the present case.     

Circadian variation in stroke onset: identical temporal pattern in ischemic and hemorrhagic events

Stroke is the culmination of a heterogeneous group of cerebrovascular diseases that is manifested as ischemia or hemorrhage of one or more blood vessels of the brain. The occurrence of many acute cardiovascular events—such as myocardial infarction, sudden cardiac death, pulmonary embolism, critical limb ischemia, and aortic aneurysm rupture—exhibits prominent 24 h patterning, with a major morning peak and secondary early evening peak. The incidence of stroke exhibits the same 24 h pattern. Although ischemic and hemorrhagic strokes are different entities and are characterized by different pathophysiological mechanisms, they share an identical double-peak 24 h pattern. A constellation of endogenous circadian rhythms and exogenous cyclic factors are involved. The staging of the circadian rhythms in vascular tone, coagulative balance, and blood pressure plus temporal patterns in posture, physical activity, emotional stress, and medication effects play central and/or triggering roles. Features of the circadian rhythm of blood pressure, in terms of their chronic and acute effects on cerebral vessels, and of coagulation are especially important. Clinical medicine has been most concerned with the prevention of stroke in the morning, when population-based studies show it is of greatest risk during the 24 h; however, improved protection of at-risk patients against stroke in the early evening, the second most vulnerable time of cerebrovascular accidents, has received relatively little attention thus far.