Role of tissue plasminogen activator in acute ischemic stroke

Exploring neuroprotective effects of PP2 in ischemic stroke via bioinformatics and experimental validation

BACKGROUND

Ischemic stroke is a leading cause of mortality and disability worldwide, yet effective therapeutic options remain limited. In this study, bioinformatics analyses were used to identify potential therapeutic targets and small-molecule compounds for ischemic stroke. A mouse model of cerebral ischemia was subsequently used to validate their neuroprotective efficacy.

METHODS

Bioinformatics methods were used to analyze and identify key signaling pathways and hub genes associated with ischemic stroke. Additionally, the Connectivity Map (CMap) database was queried to identify potential small-molecule compounds for ischemic stroke treatment. Finally, a middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model was employed to further evaluate the neuroprotective effects of the identified compounds.

RESULTS

GO and KEGG pathway enrichment analyses revealed that key signaling pathways such as TNF, NF-κB, and IL-17 play crucial roles in ischemic stroke. PPI network analysis identified five hub genes-IL-1β, IL-6, ICAM-1, Jun, and Fos-all closely associated with neuroinflammatory responses. The small-molecule compound PP2, a selective Src kinase inhibitor, was identified by CMap database. In the MCAO/R mouse model, PP2 exhibited significant neuroprotective effects. It reduced infarct volume and brain edema and improved neurological function. Mechanistically, PP2 inhibited Src phosphorylation, thereby suppressing the NF-κB signaling pathway and reducing levels of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6.

CONCLUSION

This study identifies Src kinase as a promising therapeutic target for ischemic stroke and highlights the value of bioinformatics in drug discovery and mechanistic research.

Behavioural assessment of neuropsychiatric outcomes in rodent stroke models

Stroke-associated mood disorders are less recognised than sensorimotor impairment, despite their high prevalence. Similarly, few experimental stroke studies assess non-sensorimotor functions. This study examined the prevalence and implementation of non-sensorimotor tests in three stroke-focused journals over the last twenty years. Of 965 experimental ischaemic stroke papers which used behavioural testing in rodents, 932 included sensorimotor testing, while 137 used non-sensorimotor tests (most commonly the Morris water maze, open field, Y-maze, and novel object recognition tests, but with a more diverse range of tests introduced in recent years). Cognition, anxiety and depression were assessed in 70%, 27% and 3% of these 137 papers. Non-sensorimotor deficits were typically observed after recovery of sensorimotor function. Potential confounding factors and challenges for data interpretation were identified in the most prevalent tests. More generally, experimental rigor (a priori power calculation, randomisation, blinding, and pre-defined inclusion/exclusion) improved over the years, but remained unsatisfactory with only 26% of studies providing some evidence of adequate statistical power. Furthermore, most studies focused on male animals, limiting external validity. This review confirms the disparity between sensorimotor and non-sensorimotor testing in experimental stroke but shows that the share of the studies including the latter is increasing. It is essential that research into the neuropsychiatric sequalae of stroke addresses methodological issues noted and continues to expand to improve patient outcomes post-stroke.

A first-in-human study of the anti-inflammatory profibrinolytic TMS-007, an SMTP family triprenyl phenol

AIMS

TMS-007, an SMTP family member, modulates plasminogen conformation and enhances plasminogen-fibrin binding, leading to promotion of endogenous fibrinolysis. Its anti-inflammatory action, mediated by soluble epoxide hydrolase inhibition, may contribute to its efficacy. Evidence suggests that TMS-007 can effectively treat experimental thrombotic and embolic strokes with a wide time window, while reducing haemorrhagic transformation. We aim to evaluate the safety, pharmacokinetics and pharmacodynamics of TMS-007 in healthy volunteers.

METHODS

This was a randomized, placebo-controlled, double blind, dose-escalation study, administered as a single intravenous infusion of TMS-007 in cohorts of healthy male Japanese subjects. Six cohorts were planned, but only five were completed. In each cohort (n = 8), individuals were randomized to receive one of five doses of TMS-007 (3, 15, 60, 180 or 360 mg; n = 6) or placebo (n = 2).

RESULTS

TMS-007 was generally well tolerated, and no serious adverse events were attributed to the drug. A linear dose-dependency was observed for plasma TMS-007 levels. No symptoms of bleeding were observed on brain MRI analysis, and no bleeding-related responses were found on laboratory testing. The plasma levels of the coagulation factor fibrinogen and the anti-fibrinolysis factor α₂ -antiplasmin levels were unchanged after TMS-007 dosing. A slight increase in the plasma level of plasmin-α₂ -antiplasmin complex, an index of plasmin formation, was observed in the TMS-007 group in cohort 2.

CONCLUSIONS

TMS-007 is generally well tolerated and exhibits favourable pharmacokinetic profiles that warrant further clinical development.

A Review on Therapeutic Potential of Natural Phytocompounds for Stroke

Stroke is a serious condition that results from an occlusion of blood vessels that leads to brain damage. Globally, it is the second highest cause of death, and deaths from strokes are higher in older people than in the young. There is a higher rate of cases in urban areas compared to rural due to lifestyle, food, and pollution. There is no effective single medicine for the treatment of stroke due to the multiple causes of strokes. Thrombolytic agents, such as alteplase, are the main treatment for thrombolysis, while multiple types of surgeries, such ascraniotomy, thrombectomy, carotid endarterectomy, and hydrocephalus, can be performed for various forms of stroke. In this review, we discuss some promising phytocompounds, such as flavone C-glycoside (apigenin-8-C-β-D-glucopyranoside), eriodictyol, rosamirinic acid, 6″-O-succinylapigenin, and allicin, that show effectiveness against stroke. Future study paths are given, as well as suggestions for expanding the use of medicinal plants and their formulations for stroke prevention.

Combined Therapy With Hyperbaric Oxygen and Melatonin Effectively Reduce Brain Infarct Volume and Preserve Neurological Function After Acute Ischemic Infarct in Rat

This study tested the hypothesis that combined hyperbaric oxygen (HBO) and melatonin (Mel) was superior to either one for protecting the brain functional and parenchymal integrity from acute ischemic stroke (IS) injury. Adult-male Sprague-Dawley rats were divided into groups 1 (sham-operated control), 2 (IS), 3 (IS + HBO), 4 (IS + Mel), and 5 (IS + HBO-Mel). By day 28 after IS, the brain infarct area (BIA) was lowest in group 1, highest in group 2, significantly higher in groups 3 and 4 than in group 5, but not different between groups 3 and 4. The neurological function at day 7, 14, and 28 exhibited an opposite pattern to BIA among the 5 groups. The protein expressions of inflammatory (IL-1β/IL-6/iNOS/TNF-α/p-NF-κB), apoptotic (cleaved-caspase3/cleaved-PARP/mitochondrial Bax), mitochondrial/DNA-damaged (cytochrome-C/γ-H2AX), oxidative stress (NOX-1/NOX-2), and autophagy (i.e. ratio of CL3B-II/CL3B-I) biomarkers displayed an identical pattern of BIA among 5 groups. Cellular expressions of inflammation (F4/80+/GFAP+) and DNA-damaged biomarker (γ-H2AX+) exhibited an identical pattern, whereas the integrities of myelin sheath/neuron (MPB+/NeuN+), endothelial cell (CD31+/vWF+), and number of small vessels exhibited an opposite pattern of BIA among the 5 groups. Combined HBO-Mel therapy offered an additional benefit in protecting the brain against IS injury.

An in vitro Model System for Evaluating Remote Magnetic Nanoparticle Movement and Fibrinolysis

Background

Thrombotic events continue to be a major cause of morbidity and mortality worldwide. Tissue plasminogen activator (tPA) is used for the treatment of acute ischemic stroke and other thrombotic disorders. Use of tPA is limited by its narrow therapeutic time window, hemorrhagic complications, and insufficient delivery to the location of the thrombus. Magnetic nanoparticles (MNPs) have been proposed for targeting tPA delivery. It would be advantageous to develop an improved in vitro model of clot formation, to screen thrombolytic therapies that could be enhanced by addition of MNPs, and to test magnetic drug targeting at human-sized distances.

Methods

We utilized commercially available blood and endothelial cells to construct 1/8th inch (and larger) biomimetic vascular channels in acrylic trays. MNP clusters were moved at a distance by a rotating permanent magnet and moved along the channels by surface walking. The effect of different transport media on MNP velocity was studied using video photography. MNPs with and without tPA were analyzed to determine their velocities in the channels, and their fibrinolytic effect in wells and the trays. 

Results

MNP clusters could be moved through fluids including blood, at human-sized distances, down straight or branched channels, using the rotating permanent magnet. The greatest MNP velocity was closest to the magnet: 0.76 ± 0.03 cm/sec. In serum, the average MNP velocity was 0.10 ± 0.02 cm/sec. MNPs were found to enhance tPA delivery, and cause fibrinolysis in both static and dynamic studies. Fibrinolysis was observed to occur in 85% of the dynamic MNP + tPA experiments.

Conclusion

MNPs hold great promise for use in augmenting delivery of tPA for the treatment of stroke and other thrombotic conditions. This model system facilitates side by side comparisons of MNP-facilitated drug delivery, at a human scale.

Real-World Effectiveness of Intravenous Stroke Thrombolysis is more than the Expectation of Practicing Neurologists

Background

The objective of the study was to compare the actual results of intravenous thrombolytic therapy (IVTT) in acute ischemic stroke with results anticipated by neurologists in practice.

Methods

Neurologists practicing in Thrissur metropolitan region, covering a population of 1.8 million, were telephonically surveyed about the number of yearly IVTT and their expert opinion/comment about effects of thrombolysis. This was compared with the results of IVTT from a single institution in the same region from 2012 to 2016.

Results

Eight neurologists in the region give approximately 140-150 IVTT per year. Nearly 20%-40% (median 32%) patients have good outcome, 5%-10% (median 9%) have intracerebral hematoma (ICH), and 25%-35% (median 30%) have death/bad outcome. Two neurologists from a tertiary care hospital in the region treated 122 cases of ischemic strokes with IVTT from 2012 to 2016. Age ranged from 8 to 88 years and 88 were males. Average delay in reaching hospital was 138.1 min and the door-to-needle time was 56.3 min. There were 26 cases of posterior-circulation strokes and 14 cases of cardioembolic strokes. At presentation, average National Institute of Health Stroke Scale (NIHSS) was 14.7; Modified Rankin Scale (mRS) 0.4; and CT Alberta Stroke Program Early Computerized Tomography Scores was 9.5. Good and sustained benefit (GSB) (>4 reduction in NIHSS at 24 h and 7 days) was there in 49% and no improvement (NI)/worsening in 36%. mRS 0-2 at discharge/30 days was documented in 57.3%. Symptomatic ICH was 10% (12/122) and mortality rate was 11.5% (14/122). GSB in posterior circulation strokes was 69.2% and NI/worsening in only 7.7%. mRS was 0-2 in 77% of posterior circulation strokes.

Conclusion

Contrary to the popular belief of the practicing neurologists, IVTT has a high percentage of good outcome with a reasonable bleeding risk and low rates of absolute futility.

Efficacy of SMTP-7, a small-molecule anti-inflammatory thrombolytic, in embolic stroke in monkeys

SMTP-7 (Stachybotrys microspora triprenyl phenol-7) is a small molecule that promotes thrombolysis and suppresses inflammation possibly through plasminogen modulation and soluble epoxide hydrolase (sEH) inhibition, respectively. Here, we demonstrate an efficacy of SMTP-7 in a severe embolic stroke model in monkeys. The middle cerebral artery was embolized by an autologous blood clot. Saline, SMTP-7, or tissue-type plasminogen activator (t-PA) (n = 5 in each group) was given after 3 hours, and neurologic deficit scoring and infarct characterization were performed after 24 hours. Hemorrhagic infarct-accompanied premature death was observed for two animals in t-PA group. SMTP-7 treatment significantly reduced the sizes of infarct by 65%, edema by 37%, and clot by 55% compared to saline treatment. Plasma levels of the products of plasminogen activation (plasmin-α2-antiplasmin complex) and sEH reaction (dihydroxyeicosatrienoic acid) in SMTP-7 group were 794% (P < 0.05) and 60% (P = 0.085) compared to saline group, respectively. No significant changes in the plasma levels of MMP-9, CRP, MCP-1, and S100B were found. There was an inverse correlation between plasmin-α2-antiplasmin complex level and infarct volume (r = 0.93, P < 0.05), suggesting a role of thrombolysis in the SMTP-7 action to limit infarct development. In conclusion, SMTP-7 is effective in treating severe embolic stroke in monkeys under conditions where t-PA treatment tends to cause hemorrhagic infarct-associated premature death.

Co-administration of tissue plasminogen activator and hyperbaric oxygen in ischemic stroke: a continued promise for neuroprotection

Intravenous recombinant tissue-type plasminogen activator (r-tPA, alteplase) remains the recommended therapy for acute ischemic stroke. However, several factors are limiting its practical use. It makes it urgent for us to search more efficient strategies that can save the ischemic neurons, and safely extend the time window, while in the mean time reducing the detrimental effects for stroke thrombolysis. Hyperbaric oxygen therapy (HBOT) is considered to be potentially neuroprotective. Co-administration of r-tPA and HBOT has already been proved to be effective, safe and feasible in myocardial infarction. In this article, we would like to review whether HBOT has any beneficial effects on r-tPA thrombolysis. If there is, what is the underlying possible mechanisms and how to optimize for maximal effects?

Therapeutic benefits of combined treatment with tissue plasminogen activator and 2-(4-methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-d-pyranoside in an animal model of ischemic stroke

Tissue plasminogen activator (tPA) is the only approved therapy for acute ischemic stroke, but tPA therapy is limited by a short therapeutic window and some adverse side effects. 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-d-pyranoside, a salidroside analog (code-named SalA-4g), has shown potent neuroprotective effects. In this study, a rat model of embolic middle cerebral artery occlusion (MCAO) was used to mimic ischemic stroke. The embolic MCAO rats were intravenously (iv) injected with tPA alone, SalA-4g alone, or a combination of tPA and SalA-4g. Compared to treatment with tPA alone at 4h post MCAO, combined treatment with tPA at 4h post MCAO and SalA-4g starting at 4h post MCAO and continuing for 3days at an interval of 24h significantly reduced neurological deficits and infarct volume, and significantly inhibited the intracerebral bleeding, edema formation, neuronal loss, and cellular apoptosis in the ischemic brain. Our results suggested that additive neuroprotective actions of SalA-4g contributed to widening the therapeutic window of tPA therapy and ameliorating its side effects in treating MCAO rats. The therapeutic benefits of combined treatment with tPA and SalA-4g for ischemic stroke might be associated with its effects on cerebral glucose metabolism.

Cocktail treatment, a promising strategy to treat acute cerebral ischemic stroke?

Up to now, over 1,000 experimental treatments found in cells and rodents have been difficult to translate to human ischemic stroke. Since ischemia and reperfusion, two separate stages of ischemic stroke, have different pathophysiological mechanisms leading to brain injury, a combination of protective agents targeting ischemia and reperfusion respectively may obtain substantially better results than a single agent. Normobaric hyperoxia (NBO) has been shown to exhibit neuro- and vaso-protective effects by improving tissue oxygenation when it is given during ischemia, however the effect of NBO would diminish when the duration of ischemia and reperfusion was extended. Therefore, during reperfusion drug treatment targeting inflammation, oxidative stress and free radical scavenger would be a useful adjuvant to extend the therapeutic window of tissue plasminogen activator, the only United States Food and Drug Administration (FDA) approved treatment for acute ischemic stroke. In this review, we discussed the neuro- and vaso-protective effects of NBO and recent finding of combining NBO with other drugs.

Crystal Structure of the Michaelis Complex between Tissue-type Plasminogen Activator and Plasminogen Activators Inhibitor-1

Thrombosis is a leading cause of death worldwide. Recombinant tissue-type plasminogen activator (tPA) is the Food and Drug Administration-approved thrombolytic drug. tPA is rapidly inactivated by endogenous plasminogen activator inhibitor-1 (PAI-1). Engineering on tPA to reduce its inhibition by PAI-1 without compromising its thrombolytic effect is a continuous effort. Precise details, with atomic resolution, of the molecular interactions between tPA and PAI-1 remain unknown despite previous extensive studies. Here, we report the crystal structure of the tPA·PAI-1 Michaelis complex, which shows significant differences from the structure of its urokinase-type plasminogen activator analogue, the uPA·PAI-1 Michaelis complex. The PAI-1 reactive center loop adopts a unique kinked conformation. The structure provides detailed interactions between tPA 37- and 60-loops with PAI-1. On the tPA side, the S2 and S1β pockets open up to accommodate PAI-1. This study provides structural basis to understand the specificity of PAI-1 and to design newer generation of thrombolytic agents with reduced PAI-1 inactivation.

Does normobaric hyperoxia increase oxidative stress in acute ischemic stroke? A critical review of the literature

Stroke, one of the most debilitating cerebrovascular and nuerological diseases, is a serious life-threatening condition and a leading cause of long-term adult disability and brain damage, either directly or by secondary complications. Most effective treatments for stroke are time dependent such as the only FDA-approved therapy, reperfusion with tissue-type plasminogen activator; thus, improving tissue oxygenation with normobaric hyperoxia (NBO) has been considered a logical and potential important therapy. NBO is considered a good approach because of its potential clinical advantages, and many studies suggest that NBO is neuroprotective, reducing ischemic brain injury and infarct volume in addition to improving pathologic and neurobehavorial outcomes. However, increased reactive oxygen species (ROS) generation may occur when tissue oxygen level is too high or too low. Therefore, a major concern with NBO therapy in acute ischemic stroke is the potential increase of ROS, which could exacerbate brain injury. The purpose of this review is to critically review the current literature reports on the effect of NBO treatment on ROS and oxidative stress with respect to acute ischemic stroke. Considering the available data from relevant animal models, NBO does not increase ROS or oxidative stress if applied for a short duration; therefore, the potential that NBO is a viable neuroprotective strategy for acute ischemic stroke is compelling. The benefits of NBO may significantly outweigh the risks of potential increase in ROS generation for the treatment of acute ischemic stroke.

Targeting therapeutics across the blood brain barrier (BBB), prerequisite towards thrombolytic therapy for cerebrovascular disorders-an overview and advancements

Cerebral tissues possess highly selective and dynamic protection known as blood brain barrier (BBB) that regulates brain homeostasis and provides protection against invading pathogens and various chemicals including drug molecules. Such natural protection strictly monitors entry of drug molecules often required for the management of several diseases and disorders including cerebral vascular and neurological disorders. However, in recent times, the ischemic cerebrovascular disease and clinical manifestation of acute arterial thrombosis are the most common causes of mortality and morbidity worldwide. The management of cerebral Ischemia requires immediate infusion of external thrombolytic into systemic circulation and must cross the blood brain barrier. The major challenge with available thrombolytic is their poor affinity towards the blood brain barrier and cerebral tissue subsequently. In the clinical practice, a high dose of thrombolytic often prescribed to deliver drugs across the blood brain barrier which results in drug dependent toxicity leading to damage of neuronal tissues. In recent times, more emphasis was given to utilize blood brain barrier transport mechanism to deliver drugs in neuronal tissue. The blood brain barrier expresses a series of receptor on membrane became an ideal target for selective drug delivery. In this review, the author has given more emphasis molecular biology of receptor on blood brain barrier and their potential as a carrier for drug molecules to cerebral tissues. Further, the use of nanoscale design and real-time monitoring for developed therapeutic to encounter drug dependent toxicity has been reviewed in this study.

Eligibility assessment for intravenous thrombolytic therapy in acute ischemic stroke patients; evaluating barriers for implementation

Background:

Intravenous thrombolysis is an approved treatment method for patients with acute ischemic stroke (AIS) and is recommended by multiple guidelines. However, it seems that it is less frequently used in the developing countries compared to the developed countries.

Objectives:

The purpose of this study was to estimate the percentage of patients with AIS, eligible for intravenous thrombolytic therapy, at the main referral center in Northwest Iran and to determine the main barriers for implementation of this method.

Patients and Methods:

Over one year, 647 patients who were admitted to the emergency department and met the Cincinnati Stroke Scale were enrolled into the study. The center to which patients were admitted, is a tertiary university hospital that has the required infrastructure for thrombolytic therapy in AIS. Factors recorded were neurological examinations and time between onset of symptoms and hospital arrival, hospital arrival and performance of brain computed tomography (CT) scanning, and hospital arrival to complete the investigations. Patients eligible for intravenous thrombolytic therapy were identified according to the American Heart Association (AHA) guidelines.

Results:

Mean time interval between hospital arrival and completion of brain CT scanning was 91 minutes (range: 20–378 minutes) and mean time from hospital arrival to completion of investigations was 150 minutes (range: 30–540 minutes). A total of 159 (31.3%) patients arrived at hospital within 3 hours of the onset of symptoms (early enough for intravenous thrombolytic therapy). However, 81.7% (130/159) of these patients missed thrombolytic therapy due to delayed performance of brain CT scanning and laboratory tests and 38.3% (61/159) had contraindications. The remaining 16 patients (10% of those who arrived within 3 hours and 3.1% of all cases) were eligible for thrombolytic therapy.

Conclusions:

The major barriers for thrombolytic therapy for patients with AIS in this setting were delays in the provision of in-hospital services, like initial patient assessment, CT scans or laboratory studies. These results were in contrast with previous reports.

Mechanisms of severe acute respiratory syndrome coronavirus-induced acute lung injury

Systems biology offers considerable promise in uncovering novel pathways by which viruses and other microbial pathogens interact with host signaling and expression networks to mediate disease severity. In this study, we have developed an unbiased modeling approach to identify new pathways and network connections mediating acute lung injury, using severe acute respiratory syndrome coronavirus (SARS-CoV) as a model pathogen. We utilized a time course of matched virologic, pathological, and transcriptomic data within a novel methodological framework that can detect pathway enrichment among key highly connected network genes. This unbiased approach produced a high-priority list of 4 genes in one pathway out of over 3,500 genes that were differentially expressed following SARS-CoV infection. With these data, we predicted that the urokinase and other wound repair pathways would regulate lethal versus sublethal disease following SARS-CoV infection in mice. We validated the importance of the urokinase pathway for SARS-CoV disease severity using genetically defined knockout mice, proteomic correlates of pathway activation, and pathological disease severity. The results of these studies demonstrate that a fine balance exists between host coagulation and fibrinolysin pathways regulating pathological disease outcomes, including diffuse alveolar damage and acute lung injury, following infection with highly pathogenic respiratory viruses, such as SARS-CoV.

Severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in 2002 and 2003, and infected patients developed an atypical pneumonia, acute lung injury (ALI), and acute respiratory distress syndrome (ARDS) leading to pulmonary fibrosis and death. We identified sets of differentially expressed genes that contribute to ALI and ARDS using lethal and sublethal SARS-CoV infection models. Mathematical prioritization of our gene sets identified the urokinase and extracellular matrix remodeling pathways as the most enriched pathways. By infecting Serpine1-knockout mice, we showed that the urokinase pathway had a significant effect on both lung pathology and overall SARS-CoV pathogenesis. These results demonstrate the effective use of unbiased modeling techniques for identification of high-priority host targets that regulate disease outcomes. Similar transcriptional signatures were noted in 1918 and 2009 H1N1 influenza virus-infected mice, suggesting a common, potentially treatable mechanism in development of virus-induced ALI.

L-mimosine and dimethyloxaloylglycine decrease plasminogen activation in periodontal fibroblasts

BACKGROUND

The use of prolyl hydroxylase inhibitors such as l-mimosine (L-MIM) and dimethyloxaloylglycine (DMOG) to improve angiogenesis is a new approach for periodontal regeneration. In addition to exhibiting pro-angiogenic effects, prolyl hydroxylase inhibitors can modulate the plasminogen activator system in cells from non-oral tissues. This study assesses the effect of prolyl hydroxylase inhibitors on plasminogen activation by fibroblasts from the periodontium.

METHODS

Gingival and periodontal ligament fibroblasts were incubated with L-MIM and DMOG. To investigate whether prolyl hydroxylase inhibitors modulate the net plasminogen activation, kinetic assays were performed with and without interleukin (IL)-1. Moreover, plasminogen activators and the respective inhibitors were analyzed by casein zymography, immune assays, and quantitative polymerase chain reaction.

RESULTS

The kinetic assay showed that L-MIM and DMOG reduced plasminogen activation under basal and IL-1-stimulated conditions. Casein zymography revealed that the effect of L-MIM involves a decrease in urokinase-type plasminogen activator activity. In agreement with these findings, reduced levels of urokinase-type plasminogen activator and elevated levels of plasminogen activator inhibitor 1 were observed.

CONCLUSION

L-MIM and DMOG can reduce plasminogen activation by fibroblasts from the gingiva and the periodontal ligament under basal conditions and in the presence of an inflammatory cytokine.

The use of shear stress for targeted drug delivery

Stenosed segments of arteries significantly alter the blood flow known from healthy vessels. In particular, the wall shear stress at critically stenosed arteries is at least an order of magnitude higher than in healthy situations. This alteration represents a change in physical force and might be used as a trigger signal for drug delivery. Mechano-sensitive drug delivery systems that preferentially release their payload under increased shear stress are discussed. Therefore, besides biological or chemical markers, physical triggers are a further principle approach for targeted drug delivery. We hypothesize that such a physical trigger is much more powerful to release drugs for vasodilation, plaque stabilization, or clot lysis at stenosed arteries than any known biological or chemical ones.

Normobaric hyperoxia-based neuroprotective therapies in ischemic stroke

Stroke is a leading cause of death and disability due to disturbance of blood supply to the brain. As brain is highly sensitive to hypoxia, insufficient oxygen supply is a critical event contributing to ischemic brain injury. Normobaric hyperoxia (NBO) that aims to enhance oxygen delivery to hypoxic tissues has long been considered as a logical neuroprotective therapy for ischemic stroke. To date, many possible mechanisms have been reported to elucidate NBO’s neuroprotection, such as improving tissue oxygenation, increasing cerebral blood flow, reducing oxidative stress and protecting the blood brain barrier. As ischemic stroke triggers a battery of damaging events, combining NBO with other agents or treatments that target multiple mechanisms of injury may achieve better outcome than individual treatment alone. More importantly, time loss is brain loss in acute cerebral ischemia. NBO can be a rapid therapy to attenuate or slow down the evolution of ischemic tissues towards necrosis and therefore “buy time” for reperfusion therapies. This article summarizes the current literatures on NBO as a simple, widely accessible, and potentially cost-effective therapeutic strategy for treatment of acute ischemic stroke.

Oocytes use the plasminogen-plasmin system to remove supernumerary spermatozoa

BACKGROUND

The role of the plasminogen-plasmin (PLG-PLA) system in fertilization is unknown, although its dysfunction has been associated with subfertility in humans. We have recently detected and quantified plasminogen in the oviductal fluid of two mammals and showed a reduction in sperm penetration during IVF when plasminogen is present. The objective of this study was to describe the mechanism by which PLG-PLA system regulates sperm entry into the oocyte.

METHODS AND RESULTS

By combining biochemical, functional, electron microscopic, immunocytochemical and live cell imaging methods, we show here that (i) plasminogen is activated into the protease plasmin, by gamete interaction; (ii) urokinase-type and tissue-type plasminogen activators are present in oocytes, but they are not of cortical granule origin; (iii) sperm binding to oocytes triggers the releasing of plasminogen activators and (iv) the generated plasmin causes sperm detachment from the zona pellucida.

CONCLUSIONS

Our results describe a novel mechanism for the success or failure of fertilization in mammals, by which molecules present in the oviductal environment are activated by molecules originating within the gametes. We anticipate that therapeutic up- or down-regulation of this physiological mechanism may be used to help in conception or as a contraceptive tool. Since components of the PLG-PLA system are already available as drugs for heart attacks or cancer therapies, basic research on this novel function would be rapidly transferable for clinical application.

Identification of new epilepsy treatments: issues in preclinical methodology

Preclinical research has facilitated the discovery of valuable drugs for the symptomatic treatment of epilepsy. Yet, despite these therapies, seizures are not adequately controlled in a third of all affected individuals, and comorbidities still impose a major burden on quality of life. The introduction of multiple new therapies into clinical use over the past two decades has done little to change this. There is an urgent demand to address the unmet clinical needs for: (1) new symptomatic antiseizure treatments for drug-resistant seizures with improved efficacy/tolerability profiles, (2) disease-modifying treatments that prevent or ameliorate the process of epileptogenesis, and (3) treatments for the common comorbidities that contribute to disability in people with epilepsy. New therapies also need to address the special needs of certain subpopulations, that is, age- or gender-specific treatments. Preclinical development in these treatment areas is complex due to heterogeneity in presentation and etiology, and may need to be formulated with a specific seizure, epilepsy syndrome, or comorbidity in mind. The aim of this report is to provide a framework that will help define future guidelines that improve and standardize the design, reporting, and validation of data across preclinical antiepilepsy therapy development studies targeting drug-resistant seizures, epileptogenesis, and comorbidities.