Reperfusion therapy in acute ischaemic stroke due to cervical and cerebral artery dissection: Results from a Spanish multicentre study

INTRODUCTION

Ischaemic stroke (IS) due to cervical and cerebral artery dissection (CAD) is a rare entity, and few data are available on the use of such reperfusion therapies as intravenous fibrinolysis and mechanical thrombectomy in these patients. We analysed the use of these treatments in patients with IS due to CAD and compared them against patients receiving reperfusion treatment for IS of other aetiologies.

METHODS

We conducted an observational, retrospective, multicentre study of patients with IS due to CAD recorded in the National Stroke Registry of the Spanish Society of Neurology during the period 2011-2019. Comparative analyses were performed between: a) patients with CAD treated and not treated with reperfusion therapies and b) patients treated with reperfusion for IS due to CAD and patients treated with reperfusion for IS due to other causes. Epidemiological data, stroke variables, and outcomes at discharge and at 3 months were included in the analysis.

RESULTS

The study included 21,037 patients with IS: 223 (1%) had IS due to CAD, of whom 68 (30%) received reperfusion treatment. Reperfusion treatments were used less frequently in cases of vertebral artery dissection and more frequently in patients with carotid artery occlusion. Compared to patients with IS due to other causes, patients with CAD were younger, more frequently underwent mechanical thrombectomy, and less frequently received intravenous fibrinolysis. Rates of haemorrhagic complications, mortality, and independence at 3 months were similar in both groups.

CONCLUSIONS

Reperfusion therapy is frequently used in patients with IS due to CAD. The outcomes of these patients demonstrate the efficacy and safety of reperfusion treatments, and are comparable to the outcomes of patients with IS due to other aetiologies.

Reperfusion treatment in acute ischaemic stroke due to cervical and cerebral artery dissection: results of a Spanish national multicentre study

INTRODUCTION

Ischaemic stroke (IS) due to cervical and cerebral artery dissection (CAD) is a rare entity, and few data are available on the use of such reperfusion therapies as intravenous fibrinolysis and mechanical thrombectomy in these patients. We analysed the use of these treatments in patients with IS due to CAD and compared them against patients receiving reperfusion treatment for IS of other aetiologies.

METHOD

We conducted an observational, retrospective, multicentre study of patients with IS due to CAD recorded in the National Stroke Registry of the Spanish Society of Neurology during the period 2011-2019. Comparative analyses were performed between: a) patients with CAD treated and not treated with reperfusion therapies and b) patients treated with reperfusion for IS due to CAD and patients treated with reperfusion for IS due to other causes. Epidemiological data, stroke variables, and outcomes at discharge and at 3 months were included in the analysis.

RESULTS

The study included 21,037 patients with IS: 223 (1%) had IS due to CAD, of whom 68 (30%) received reperfusion treatment. Reperfusion treatments were used less frequently in cases of vertebral artery dissection and more frequently in patients with carotid artery occlusion. Compared to patients with IS due to other causes, patients with CAD were younger, more frequently underwent mechanical thrombectomy, and less frequently received intravenous fibrinolysis. Rates of haemorrhagic complications, mortality, and independence at 3 months were similar in both groups.

CONCLUSIONS

Reperfusion therapy is frequently used in patients with IS due to CAD. The outcomes of these patients demonstrate the efficacy and safety of reperfusion treatments, and are comparable to the outcomes of patients with IS due to other aetiologies.

Cognitive profile following COVID-19 infection: Clinical predictors leading to neuropsychological impairment

Background

Cognitive manifestations associated with the severity of a novel coronavirus (COVID-19) infection are unknown. An early detection of neuropsychological manifestations could modify the risk of subsequent irreversible impairment and further neurocognitive decline.

Methods

In our single-center cohort study, we included all consecutive adult patients, aged between 20 and 60 years old with confirmed COVID-19 infection. Neuropsychological assessment was performed by the same trained neuropsychologist from April, 22nd through June 16th, 2020. Patients with previous known cognitive impairment, any central nervous system or psychiatric disease were excluded. Demographic, clinical, pharmacological and laboratory data were extracted from medical records.

Results

Thirty-five patients met inclusion criteria and were included in the study. Patients presenting headache, anosmia, dysgeusia, diarrhea and those who required oxygen therapy had lower scores in memory, attention and executive function subtests as compared to asymptomatic patients. Patients with headache and clinical hypoxia scored lower in the global Cognitive Index (P ​= ​0.002, P ​= ​0.010). A T score lower than 30 was observed in memory domains, attention and semantic fluency (2 [5.7%]) in working memory and mental flexibility (3 [8.6%]) and in phonetic fluency (4 [11.4%]). Higher scores in anxiety and depression (P ​= ​0.047, P ​= ​0.008) were found in patients with cognitive complaints.

Conclusions

In our cohort of COVID-19 patients neurologic manifestations were frequent, including cognitive impairment. Neurological symptoms during infection, diarrhea and oxygen therapy were risk factors for neurocognitive impairment. Cognitive complaints were associated with anxiety and depression.

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Neuropsychological deficits related to COVID-19 infection were seen in attention, memory and executive function domains.

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Presenting neurological symptoms during COVID-19 infection were risk factors for cognitive deficit.

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Oxygen therapy, headache and diarrhea were symptoms associated to poor performance in neuropsychological tests.

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Cognitive complains in patients with COVID-19 were associated with anxiety and depressive symptoms.

Outcomes After Direct Thrombectomy or Combined Intravenous and Endovascular Treatment Are Not Different

Background and Purpose—

Whether intravenous thrombolysis adds a further benefit when given before endovascular thrombectomy (EVT) is unknown. Furthermore, intravenous thrombolysis delays time to groin puncture, mainly among drip and ship patients.

Methods—

Using region-wide registry data, we selected cases that received direct EVT or combined intravenous thrombolysis+EVT for anterior circulation strokes between January 2011 and October 2015. Treatment effect was estimated by stratification on a propensity score. The average odds ratios for the association of treatment with good outcome and death at 3 months and symptomatic bleedings at 24 hours were calculated with the Mantel–Haenszel test statistic.

Results—

We included 599 direct EVT patients and 567 patients with combined treatment. Stratification through propensity score achieved balance of baseline characteristics across treatment groups. There was no association between treatment modality and good outcome (odds ratio, 0.97; 95% confidence interval, 0.74–1.27), death (odds ratio, 1.07; 95% confidence interval, 0.74–1.54), or symptomatic bleedings (odds ratio, 0.56; 95% confidence interval, 0.25–1.27).

Conclusions—

This observational study suggests that outcomes after direct EVT or combined intravenous thrombolysis+EVT are not different. If confirmed by a randomized controlled trial, it may have a significant impact on organization of stroke systems of care.

Monomeric C-reactive protein--a key molecule driving development of Alzheimer's disease associated with brain ischaemia?

Alzheimer’s disease (AD) increases dramatically in patients with ischaemic stroke. Monomeric C-reactive protein (mCRP) appears in the ECM of ischaemic tissue after stroke, associating with microvasculature, neurons and AD-plaques, Aβ, also, being able to dissociate native-CRP into inflammatory, mCRP in vivo. Here, mCRP injected into the hippocampal region of mice was retained within the retrosplenial tract of the dorsal 3rd ventrical and surrounding major vessels. Mice developed behavioural/cognitive deficits within 1 month, concomitant with mCRP staining within abnormal looking neurons expressing p-tau and in beta-amyloid 1-42-plaque positive regions. mCRP co-localised with CD105 in microvessels suggesting angiogenesis. Phospho-arrays/Western blotting identified signalling activation in endothelial cells and neurons through p-IRS-1, p-Tau and p-ERK1/2-which was blocked following pre-incubation with mCRP-antibody. mCRP increased vascular monolayer permeability and gap junctions, increased NCAM expression and produced haemorrhagic angiogenesis in mouse matrigel implants. mCRP induced tau244–372 aggregation and assembly in vitro. IHC study of human AD/stroke patients revealed co-localization of mCRP with Aβ plaques, tau-like fibrils and IRS-1/P-Tau positive neurons and high mCRP-levels spreading from infarcted core regions matched reduced expression of Aβ/Tau. mCRP may be responsible for promoting dementia after ischaemia and mCRP clearance could inform therapeutic avenues to reduce the risk of future dementia.

Expression of the vitamin K-dependent proteins GAS6 and protein S and the TAM receptor tyrosine kinases in human atherosclerotic carotid plaques

The GAS6/ProS-TAM system is composed of two vitamin K-dependent ligands (GAS6 and protein S) and their three protein tyrosine kinase receptors TYRO3, AXL and MERTK, known as the TAM receptors. The system plays a prominent role in conditions of injury, inflammation and repair. In murine models of atherosclerotic plaque formation, mutations in its components affect atherosclerosis severity. Here we used Taqman low-density arrays and immunoblotting to study mRNA and protein expression of GAS6, ProS and the TAM receptors in human carotid arteries with different degrees of atherosclerosis. The results show a clear down-regulation of the expression of AXL in atheroma plaques with respect to normal carotids that is matched by decreased abundance of AXL in protein extracts detected by immunoblotting. A similar decrease was observed in PROS1 mRNA expression in atherosclerotic carotids compared to the normal ones, but in this case protein S (ProS) was clearly increased in protein extracts of carotid arteries with increasing grade of atherosclerosis, suggesting that ProS is carried into the plaque. MERTK was also increased in atherosclerotic carotid arteries with respect to the normal ones, suggesting that the ProS-MERTK axis is functional in advanced human atherosclerotic plaques. MERTK was expressed in macrophages, frequently in association with ProS, while ProS was abundant also in the necrotic core. Our data suggest that the ProS-MERTK ligand-receptor pair was active in advanced stages of atherosclerosis, while AXL signalling is probably down-regulated.

A role for monomeric C-reactive protein in regulation of angiogenesis, endothelial cell inflammation and thrombus formation in cardiovascular/cerebrovascular disease?

Native CRP (nCRP) is a pentameric oligoprotein composed of identical 23 KDa subunits which can be irreversibly dissociated to form free subunits or monomeric CRP (mCRP). mCRP has a reduced aqueous solubility and a tendency to aggregate into matrix-like lattices in various tissues, in particular, blood vessel walls. A dramatic increase in expression of mCRP occurs in angiogenic blood vessels derived from stroked brain regions, atherosclerotic arteries and active vessels from other angiogenic diseases such as Alzheimer's. Furthermore, mCRP unlike the native molecule is highly angiogenic to vascular endothelial cells in vitro and therefore might impact on the processes of vascularization and re-modelling thus affecting tissue survival and development. In this mini-review, we will discuss the differences in the biological properties between nCRP and mCRP. We will provide a brief historical background to the importance of nCRP as a biomarker for cardiovascular disease. We will explain the mechanisms of conversion of nCRP to its monomeric form and describe evidence for the role of mCRP in modulation of endothelial cell activation, promotion of inflammatory status and thrombus formation in cardio/cerebrovascular disease. Finally, we will provide evidence for the accumulation of mCRP in angiogenic microvessels from diseased tissue, and demonstrate its highly pro-angiogenic capabilities. The discovery of the existence of this tissue-associated, highly angiogenic monomeric form of CRP capable of cellular binding and intra-cellular signal transduction activation may help in our understanding of the processes responsible for modulation of angiogenesis and inflammation in disease.

Combining nanotechnology with current biomedical knowledge for the vascular imaging and treatment of atherosclerosis

Activation of vasa vasorum (the microvessels supplying the major arteries) at specific sites in the adventitia initiates their proliferation or 'angiogenesis' concomitant with development of atherosclerotic plaques. Haemorrhagic, leaky blood vessels from unstable plaques proliferate abnormally, are of relatively large calibre but are immature neovessels poorly invested with smooth muscle cells and possess structural weaknesses which may contribute to instability of the plaque by facilitation of inflammatory cell infiltration and haemorrhagic complications. Weak neovascular beds in plaque intima as well as activated adventitial blood vessels are potential targets for molecular imaging and targeted drug therapy, however, the majority of tested, currently available imaging and therapeutic agents have been unsuccessful because of their limited capacity to reach and remain stably within the target tissue or cells in vivo. Nanoparticle technology together with magnetic resonance imaging has allowed the possibility of imaging of neovessels in coronary or carotid plaques, and infusion of nanoparticle suspensions using infusion catheters or implant-based drug delivery represents a novel and potentially much more efficient option for treatment. This review will describe the importance of angiogenesis in mediation of plaque growth and development of plaque instability and go on to investigate the possibility of future design of superparamagnetic/perfluorocarbon-derived nanoparticles for imaging of the vasculature in this disease or which could be directed to the adventitial vasa vasorum or indeed intimal microvessels and which can release active payloads directed against primary key external mitogens and intracellular signalling molecules in endothelial cells responsible for their activation with a view to inhibition of angiogenesis.

Atherothrombosis and plaque heterology: different location or a unique disease?

Formation of unstable plaques frequently results in atherothrombosis, the major cause for ischaemic stroke, myocardial infarction and peripheral arterial disease. Patients who have symptomatic thrombosis in one vascular bed are at increased risk of disease in other beds. However, the development of the disease in carotid, coronary and peripheral arteries may have different pathophysiology suggesting that more complex treatment protocols may have to be designed to reduce plaque development at different locations. In this review we describe the known risk factors, compare the developmental features of coronary and carotid plaque development and determine their association with end-point ischaemic events. Differences are also seen in the genetic contribution to plaque development as well as in the deregulation of gene and protein expression and cellular signal transduction activity of active cells in regions susceptible to thrombosis. Differences between carotid and coronary artery plaque development might help to explain the differences in anatomopathological appearance and risk of rupture.

Simvastatin in the acute phase of ischemic stroke: a safety and efficacy pilot trial

Although statins are being used for secondary prevention of ischemic stroke, recent experimental data have shown new pleiotropic effects of these drugs responsible for their role in neuroprotection. We conducted a pilot, double-blind, randomized, multicenter clinical trial to study for the first time safety and efficacy of simvastatin in the acute phase of ischemic stroke. Simvastatin/placebo was given at 3-12 h from symptom onset to 60 patients with cortical strokes. Efficacy on the evolution of several inflammation markers [interleukin (IL)-6, IL-8, IL-10, monocyte chemoattractant protein-1, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, C-reactive protein, sApo/Fas, tumor necrosis factor-alpha, E-selectin, L-selectin and nitrites+nitrates] and neurological outcome was evaluated at baseline, day 1, 3, 5, 7 and 90. No differences were found amongst the biomarkers studied regarding treatment allocation. Although simvastatin patients improved significantly by the third day (46.4% vs. 17.9%, P = 0.022), a non-significant increase in mortality and greater proportion of infections (odds ratio 2.4, confidence interval 1.06-5.4) in the simvastatin group were the main safety concerns. Therefore, a larger clinical trial is needed to confirm the net benefit of this therapeutic approach.

Leukaemia inhibitory factor is over-expressed by ischaemic brain tissue concomitant with reduced plasma expression following acute stroke

Leukaemia inhibitory factor (LIF) is a glycoprotein of the interleukin-6 family, which has potent pro-inflammatory properties and is involved in regulation of neuronal differentiation. We have previously identified its upregulation in gene microarrays following acute ischaemic stroke in man. LIF expression and localization was measured in human ischaemic stroke autopsy specimens, in a rat model of middle cerebral artery occlusion (MCAO) and in human foetal neural cell cultures following oxygen-glucose deprivation (OGD) by Western blotting and immunohistochemistry. Circulating LIF was determined in the plasma of patients in the hyper-acute stroke phase using a multiplex enzyme-linked-immunosorbent serologic assay system. Patients demonstrated an increase in LIF expression in peri-infarcted regions with localization in neurons and endothelial cells of microvessels surrounding the infarcted core. The rat MCAO model showed similar upregulation in neurons with a peak increase at 90 min. Circulating serum LIF expression was significantly decreased in the hyper-acute phase of stroke. Brain-derived neurons and glia cultured in vitro demonstrated an increase in gene/protein and protein expression respectively following exposure to OGD. Increased LIF expression in peri-infarcted regions and sequestration from the peripheral circulation in acute stroke patients are characteristic of the pathobiological response to ischaemia and tissue damage.

Pathophysiology of Acute Ischaemic Stroke: An Analysis of Common Signalling Mechanisms and Identification of New Molecular Targets

Stroke continues to be a major cause of death and disability. The currently available therapies have proven to be highly unsatisfactory (except thrombolysis) and attempts are being made to identify and characterize signalling proteins which could be exploited to design novel therapeutic modalities. The pathophysiology of stroke is a complex process. Delaying interventions from the first hours to days or even weeks following blood vessel occlusion may lead to worsening or impairment of recovery in later stages. The objective of this review is to critically evaluate the major mechanisms underlying stroke pathophysiology, especially the role of cell signalling in excitotoxicity, inflammation, apoptosis, neuroprotection and angiogenesis, and highlight potential novel targets for drug discovery.

Citicoline inhibits MAP kinase signalling pathways after focal cerebral ischaemia

The link between membrane phospholipids and different intracellular signal transduction pathways affected by cerebral ischaemia is unclear. CDP-choline, a major neuronal membrane lipid precursor and its intracellular target proteins and transcription factors were studied to further understand its role in ischaemic stroke. Cerebral ischaemia was produced by distal, permanent occlusion of the middle cerebral artery (MCAO) in the rat. Animals receiving 500 mg/kg of CDP-choline in 0.5 ml of 0.9% saline, intraperitoneally, 24 h and 1 h before MCAO and 23 h after MCAO demonstrated a notable reduction in the phosphorylation of MAP-kinase family members, ERK1/2 and MEK1/2, as well as Elk-1 transcription factor, compared with control animals treated with 0.5 ml of 0.9% saline. Immunohistochemistry showed a particular reduction in immunoreactivity in glia. The effects of CDP-choline on intracellular mechanisms of signal transduction, suggests that this molecule may play a key role in recovery after ischaemic stroke.

Gene activation and protein expression following ischaemic stroke: strategies towards neuroprotection

Current understanding of the patho-physiological events that follow acute ischaemic stroke suggests that treatment regimens could be improved by manipulation of gene transcription and protein activation, especially in the penumbra region adjacent to the infarct. An immediate reduction in excitotoxicity in response to hypoxia, as well as the subsequent inflammatory response, and beneficial control of reperfusion via collateral revascularization near the ischaemic border, together with greater control over apoptotic cell death, could improve neuronal survival and ultimately patient recovery. Highly significant differences in gene activation between animal models for stroke by middle cerebral artery occlusion, and stroke in patients, may explain why current treatment strategies based on animal models of stroke often fail. We have highlighted the complexities of cellular regulation and demonstrated a requirement for detailed studies examining cell specific protective mechanisms after stroke in humans.

Time-course phosphorylation of the mitogen activated protein (MAP) kinase group of signalling proteins and related molecules following middle cerebral artery occlusion (MCAO) in rats

Recovery from the debilitating effects of ischaemic stroke is variable and unpredictable. To maximize patient recovery, a greater understanding of the molecular mechanisms involved in regulating both apoptosis and the repair processes affecting neuronal protection, particularly in the penumbra region, is desirable. We have previously shown, in human subjects, the increased expression of several growth factors soon after stroke, together with appearance of tyrosine phosphorylated proteins, in particular mitogen activated protein (MAP) kinase (ERK1/2). In this paper, we demonstrate a relatively short-lasting (< 12 h), but substantial increase in expression of phosphorylated proteins, in particular, p-JNK (phosphorylated c-Jun N-terminal kinase) and p-ERK1/2 in both the grey matter penumbra and infarcted tissue of rats, following permanent middle cerebral artery occlusion. p-ERK1/2 was associated with neurones and endothelial cells in the vicinity of the infarct while p-JNK was mainly expressed in neurones. Expression of both p-MEK3/6 and p-p38 MAP kinase was also increased in neurones and astroglia, within 1 h of infarction, p-p38 remaining elevated and associated with neurones and in particular with astroglia in the penumbra region for > 4 days. Evidence suggests that short-term activation of these proteins may be detrimental to neuronal survival, while their transient nature makes them unlikely to support angiogenesis, revascularization and reperfusion over a period of days and weeks. On the other hand, short-medium-term up-regulation of neuronal p-JNK, p-c-Jun, p-Stat-1 and p-p38 might be a factor in the regulation of apoptosis. Therapeutic manipulation of phosphorylation/activation of these and other important signalling intermediates might form the basis of an appropriate treatment to maximize revascularization and neuronal protection after ischaemic stroke.

CDP-choline reduces pro-caspase and cleaved caspase-3 expression, nuclear DNA fragmentation, and specific PARP-cleaved products of caspase activation following middle cerebral artery occlusion in the rat

Citicoline has been demonstrated to be beneficial in several models of cerebral ischaemia. We tested the hypothesis that citicoline may provide apoptotic pathways following focal cerebral ischaemia. Focal cerebral ischaemia was produced by distal, permanent middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats. The animals were randomised into four groups: (B+A) Citicoline 500 mg/kg IP 24 and 1 h before MCAO, and 23 h after MCAO; (A) citicoline 500 mg/kg IP, within 30 min after MCAO, and 23 h after MCAO; (C) vehicle IP; and (D) sham-operated. The animals were sacrificed at 12 h (n=8 per group) and 24 h (n=8 per group) after MCAO. Immunohistochemistry was performed on free-floating tissue sections with goat polyclonal antibodies to procaspase-1, -2, -3, -6 and -8, and in paraffin-embedded sections processed for cleaved caspase-3 (17 kDa) immunohistochemistry. Finally, some sections were stained with the method of in situ end-labelling of nuclear DNA fragmentation. For gel electrophoresis and Western blotting, antibodies to poly (ADP-ribose) polymerase (PARP) products of 89 kDa were used to reveal specific cleavage substrates of caspases. MCAO induced the expression of all procaspases and the expression of PARP products of 89 kDa, as well as cells with nuclear DNA fragmentation, at 12 and 24 h, in the infarcted core and penumbra. Citicoline reduced the expression of all procaspases at 12 and 24 h after MCAO, as well as the expression of cleaved caspase-3 in cells in the penumbra area. This was accompanied by a reduction in the number of cells bearing nuclear DNA fragments. The expression of caspase-cleaved products of PARP (PARP 89 kDa) was reduced in citicoline-treated ischaemic rats. These results show that citicoline inhibits the expression of proteins involved in apoptosis following MCAO.

The identification and treatment of depression by general practitioners

OBJECTIVE

To assess the level of recognition and knowledge about treatment of depression by General Practitioners (GPs).

METHOD

Analysis of questionnaires completed by participants commencing a series of workshops aimed at improving their knowledge of the diagnosis and treatment of depression. Of the 3289 GPs involved in the program 2500 (76% respondent rate) completed the questionnaires in a group situation. There was no difference between respondents and nonrespondents in terms of age, gender and year of graduation.

RESULTS

The majority of GPs believe they have a satisfactory competence in the recognition and treatment of depression, although a sizeable minority based their diagnosis predominantly on somatic symptoms. The GPs felt confident about their knowledge and skills in counselling and the use of antidepressant medication, but not in dealing with children and suicidal or pregnant patients. The most common symptoms used to identify 'depression' were sleep disorders and only 54% listed depressed mood as a symptom on which the diagnosis is based. Only 28% reported sufficient symptoms to meet criteria for DSM-IV major depressive disorder, which supports views that these criteria are inappropriate for general practice. Fifty-seven percent of doctors used medicine together with nonpharmacological treatment in the majority of patients, and medications doses were almost all within the range recommended in the product information.

CONCLUSIONS

There is a need to improve GPs knowledge in diagnosing depression, in child psychiatry and in dealing with pregnant and suicidal patients.

The discovery of novel, potent and selective PDE5 inhibitors

The design and synthesis of a novel scaffold for potent and selective PDE5 inhibitors are described. Compound 3a was more potent (PDE5 IC50=0.31 nM) and selective (>10,000-fold vs PDE1 and 160-fold selective vs PDE6) PDE5 inhibitor than sildenafil.

Brain-derived neurotrophic factor reduces cortical cell death by ischemia after middle cerebral artery occlusion in the rat

Stroke is the major cause of adult brain dysfunction. In an experimental approach to evaluate the possible beneficial effects of administration of neurotrophic factors in stroke, we have used a model of distal middle cerebral artery (MCA) occlusion in adult rats. In this model, we found: (1) a permanent reduction of brain-derived neurotrophic factor (BDNF) and its full-length receptor, TrkB, in the infarcted core; (2) a transient increase in BDNF immunoreactivity in the internal region of the border of the infarct (penumbra area) at 12 h after MCA occlusion; (3) increased truncated TrkB immunoreactivity in astrocytes surrounding the area of the infarction; and (4) increased full-length TrkB immunoreactivity in scattered neurons, distant from the infarct, in ipsilateral and contralateral cortices at 24 and 48 h after MCA occlusion. We next studied the regulation of TrkB expression by BDNF, after ischemia, and its neuroprotective effects in vivo. In control non-ischemic rats, grafting of mock- or BDNF-transfected fibroblasts (F3A-MT or F3N-BDNF cell lines, respectively) in the medial part of the somatosensory cortex increased truncated TrkB immunoreactivity in neighboring astrocytes. Grafting alone also increased full-length TrkB in the vicinity of the mock graft (at 24 and 48 h) and the BDNF-grafted graft (at 4 days). Interestingly, ischemic animals grafted with the mock-transfected cell line did not show any further regulation of TrkB receptors. However, ischemic animals grafted with the BDNF cell line showed an up-regulation of full-length TrkB expression in neurons located in the internal border of the infarct. Analysis of nuclear DNA fragmentation in situ, combined with microtubule-associated protein 2 immunohistochemistry, revealed that most cells dying in the borders of the infarct (penumbra area) at 48 h following MCA occlusion were neurons. No differences in the infarct size were found between MCA occluded, mock-transfected MCA-occluded, and BDNF-transfected MCA-occluded rats. Moreover, cell death was similar in nongrafted and mock-grafted rats subjected to MCA occlusion. However, the number of cells with nuclear DNA breaks was significantly reduced in the penumbra area close to the BDNF graft in ischemic rats. Thus, our results show that BDNF specifically up-regulates its full-length TrkB receptor in cortical neurons of the penumbra area and prevents their death in an in vivo model of focal ischemia.

Optimization of substituted N-3-benzylimidazoquinazolinone sulfonamides as potent and selective PDE5 inhibitors

A previous report from these laboratories identified the N-3-benzylimidazoquinazolinone nucleus as a more selective PDE5 inhibitor template compared to the pyrazolopyrimidine of sildenafil. This paper describes in detail the structure-activity relationships of a set of sulfonamide analogues, several of which are both more potent and more selective PDE5 inhibitors in vitro than sildenafil. The synthesis, in vitro enzyme activity and selectivity, and in vitro functional and preclinical pharmacokinetic assessment of molecules in this series are described.

Activation of MAP kinase (ERK-1/ERK-2), tyrosine kinase and VEGF in the human brain following acute ischaemic stroke

We examined expression of vascular endothelial growth factor (VEGF), phosphorylation of mitogen activated protein kinase (MAP) kinase (ERK1 and ERK2) and tyrosine phosphorylation in 19 patients (aged 58-90 years; mean 75) who died 1-44 days after acute ischaemic stroke. In the grey matter penumbra, 13 of 19 patients showed an increase in MAP kinase tyrosine phosphorylation (ERK1; 2.0- to 8-fold, ERK2; 2.2- to 11-fold) compared with normal contralateral tissue. In almost all cases, ERK-2 phosphorylation was higher than ERK1. Of these 13 patients, 11 also showed a general increase in tyrosine kinase phosphorylation, and eight expressed increased levels of VEGF protein (2.5- to 5-fold). In tissue examined directly from the infarct core, activation of the above proteins was not observed in the, majority of patients. In the white matter, seven of 19 patients (penumbra), and nine of 19 patients (stroke) had an increase in MAP kinase tyrosine phosphorylation (ERK1; 2.0- to 4.6-fold and ERK-2; 2.3- to 5.4-fold respectively) compared with normal contralateral tissue. There was no relationship between activation of MAP kinase and expression of VEGF. Examination of phosphorylated MAP kinase by immunohistochemistry revealed an increase in immunoreactivity in neurones, astroglial cells, reactive microglia and endothelial cells in areas surrounding infarcts, especially in areas with the highest density of microvessels. In conclusion, chronic activation of tyrosine phosphorylated events, in particular redistribution and phosphorylation of MAP kinase (ERK1/ERK2) occurs consistently in the grey matter penumbra of brain tissue following ischaemic stroke, and may be associated with increase in expression of VEGF. These signal transduction events could be important determinants of the extent of neuronal survival and/or angiogenic activity in the recovering brain tissue.

Serial measurement of vascular endothelial growth factor and transforming growth factor-beta1 in serum of patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Both vascular endothelial growth factor (VEGF) and transforming growth factor-beta1 (TGF-beta1) are expressed in higher than normal concentrations in the penumbra of patients after ischemic stroke. Because both cytokines are central to the processes of angiogenesis, tissue inflammation, and fibrosis, we performed serial measurements of these cytokines in patients with cerebral infarction and determined their relationship to stroke etiology and volume.

METHODS

We serially (at days 0, 1, 3, 7, and 14) measured the serum levels of VEGF and active TGF-beta1 in 29 patients with acute ischemic stroke. Age-matched healthy subjects (n=26) were used as controls.

RESULTS

Expression of VEGF was significantly increased in the majority of patients after acute stroke at each of the time points compared with normal controls. Highest expression occurred at day 7 (588+/-121 pg/mL; P=0.005), and it remained significantly elevated at 14 days after stroke. Expression of VEGF correlated with infarct volume, clinical disability (Scandinavian Stroke Scale), and peripheral leukocytosis and was significantly higher in patients with atherothrombotic large-vessel disease and ischemic heart disease (P<0.05 in all cases). In contrast, expression of active TGF-beta1 was not significantly different from control patients at any of the measured time points. When the mean concentration of TGF-beta1 from each patient (pooled time points) was compared with the control mean, a significant increase was found in only 2 patients, whereas levels decreased in 12 patients (P<0.05). There was no correlation between circulating active TGF-beta1 and VEGF expression, leukocytosis, stroke subtype, or patient disability as assessed by Scandinavian Stroke Scale score.

CONCLUSIONS

VEGF but not TGF-beta1 showed a dramatic increase in serum of stroke patients. Correlation between stroke severity and VEGF concentration suggests it could be involved in the subsequent repair processes resulting in partial recovery after stroke. Correlation between VEGF expression and peripheral leukocytosis suggests that these changes may also reflect the immunologic status of the patient. VEGF may play an important role in the pathophysiology of acute ischemic stroke and could be of value in future treatment strategies.

Expression of caspases and their substrates in the rat model of focal cerebral ischemia

Experimental evidence suggests that the massive release of glutamate during experimental brain ischemia both directly and indirectly regulates downstream mechanisms of cell suicide. Cerebral ischemia was produced by distal, permanent occlusion of the middle cerebral artery (MCAO) in the rat. Sets of three animals and one sham-operated for each time-point were kept alive for 0-30 min, 1, 4, 12, 24, and 48 h, and 4 days. Additional animals were treated by local administration of a 10 microM (in 10 microl) cocktail of caspase inhibitors (YVAD-cmk, DEVD-fmk, IETD). Immunohistochemistry was performed on free-floating tissue sections with goat polyclonal antibodies to procaspase-1, -2, -3, -6, and -8. Some sections were processed for double-labeling procaspase immunohistochemistry and in situ end-labeling of nuclear DNA fragmentation (TUNEL method). Both immunohistochemistry and double-labeling procaspase immunohistochemistry and TUNEL method were carried out on formalin-fixed sections. For gel electrophoresis and Western blotting, we used antibodies to poly (ADP-ribose) polymerase (PARP), lamin B, and PKC-delta, as specific cleavage substrates of caspases. There was increased immunoreactivity ipsilaterally in the areas corresponding to the infarct and surrounding penumbra with the peak of immunoreactivity between 12 and 24 h for most of the procaspases. Procaspases were present early in the infarcted tissue neurones and their dendrites and axons. Additional procaspase expression occurred in astrocytes and microglial cells at different times following ischemia. Cells with positive in situ end-labeling of nuclear DNA fragmentation appeared in high number predominantly in the infarcted areas and at the edge of the infarction and colocalized with enhanced procaspase expression. These findings suggest increased procaspase expression in dying cells at the edge of the infarction. A major product of PARP degradation of about 89 kDa was found in the samples taken from the infarcted and penumbra areas. There was no difference in the intensity of the bands corresponding to lamin B or PKC-delta. Injection of procaspase inhibitors reduced the levels of major PARP products of 89 kDa and decreased the number of TUNEL-positive cells at 12 h post-MCAO. In conclusion, these results give support to further research on the use of caspase inhibitors as add-on therapeutic agents for the treatment of ischemia.

N-3-substituted imidazoquinazolinones: potent and selective PDE5 inhibitors as potential agents for treatment of erectile dysfunction

Phosphodiesterase type 5 (PDE5) inhibitors with improved PDE isozyme selectivity relative to sildenafil may result in agents for the treatment of male erectile dysfunction (MED) with a lower incidence of PDE-associated adverse effects. This paper describes the discovery of 14, a PDE5 inhibitor with improved potency and selectivity in vitro compared to sildenafil. This compound shows activity in a functional assay of erectile function comparable to that of sildenafil.

Differential c-Fos and caspase expression following kainic acid excitotoxicity

Caspases play crucial roles in the inflammatory response and in the cell pathway leading to apoptosis. Caspase 1 (ICE), 2 (Nedd2), 3 (CPP32), 6 (Mch2) and 8 (Mch5, FLICE) expression was examined using immunohistochemistry in the brains of rats and gerbils following systemic administration of kainic acid (KA). The distribution of caspase expression was compared with the distribution of c-Fos expression, a transcription factor that is produced in response to the excitotoxic insult. Strong caspase 2 immunoreactivity was found in microglia up to 6 h following KA administration. Focal strong expression of caspases 1, 2, 3, 6 and 8 was observed in astrocytes and neurons, from 12 to 48 h after KA injection, in areas in which a number of neurons were committed to die. This distribution was in contrast with the generalised distribution of c-Fos expression following KA administration. Only a minority of neurons in the entorhinal cortex, amygdala and hilus, but a majority of neurons in selected thalamic nuclei, exhibited strong caspase expression in KA-treated rats. Similar findings, although minimised, were observed in KA-treated gerbils. Double-labelling caspase immunohistochemistry and in situ end-labelling of nuclear DNA fragmentation disclosed co-localisation of strong caspase expression and nuclear DNA breaks in a small percentage of neurons but no co-localisation in astrocytes. Western blots of entorhinal cortex and neocortex homogenates showed cleavage of certain caspase substrates in KA-treated rats. The intensity of the bands corresponding to lamin B and protein kinase C-delta was decreased in the entorhinal cortex following KA administration. Several bands appeared in the entorhinal cortex and neocortex paragraph signin Western blots processed for the demonstration of poly(ADP-ribose) polymerase (PARP), thus indicating that other proteases, in addition to caspases, cleaved PARP following KA administration. Taken together, these findings indicate that KA excitotoxicity triggers caspase expression which, although predominant in regions subjected to irreversible cell damage, has only a weak association with the presence of nuclear DNA breaks and neuron cell death. Although these results suggest caspase activation, further studies have to be performed to elucidate whether caspase activation plays a crucial role in KA excitotoxicity.

Factors influencing the frequency of fluorescence transients as markers of peri-infarct depolarizations in focal cerebral ischemia

BACKGROUND AND PURPOSE

Peri-infarct depolarizations (PIDs) that occur in ischemic boundary zones of the cerebral cortex of experimental animals have been shown to promote rather than simply to indicate the evolution of the lesion and are especially prominent in the rat. To study the influence of one factor, species, on PID incidence, we compared the frequency of PIDs in a primate species, the squirrel monkey, with that in the cat after middle cerebral artery occlusion. Plasma glucose was reviewed as a possible cause of interexperiment variability in the cat experiments.

METHODS

In open-skull experiments under chloralose anesthesia, changes in cortical fluorescence believed to indicate NADH/NAD(+) redox state, as markers of PIDs, were recorded by serial imaging of the cortical surface in vivo for 4 hours after middle cerebral artery occlusion.

RESULTS

Fluorescence transients occurred in squirrel monkeys at a frequency (mean+/-SD) of 0.7+/-0.8 hours(-1) (n=5), which was not significantly less than in that observed in cats (1.3+/-1.6 hours(-1), n=8). Data from the cat experiments indicated a relationship between number of transients (dependent) and plasma glucose, with a striking increase in PID frequency in association with values of mean postocclusion plasma glucose <4.1 mmol/L (Mann-Whitney U=15.0, P=0.034); this observation agrees well with other published findings.

CONCLUSIONS

Transient changes in fluorescence strongly suggestive of peri-infarct depolarizations, either transient or terminal, occur and propagate in the ischemic cerebral cortex of a nonhuman primate. The results also suggest that the relationship of frequency of peri-infarct depolarizations with plasma glucose requires further examination, to confirm the finding and to determine a safe lower limit for a target range for control of plasma glucose if insulin is used in the management of patients with cerebral ischemia.

Acoustic analysis of dysarthria profile in ALS patients

Dysarthria is a leading disability in ALS patients with motor neurone degeneration in the bulbar region. Although different approaches have been tried in the past, currently, no test is available to detect and follow the progression of dysarthria. We studied 53 patients with definite (n=27) or probable (n=26) ALS (the bulbar onset group n=15, the limb onset group n=38, mean age 53. 66/29-76 years/) according to El Escorial criteria. Each patient was seen by a neurologist every 10-12 weeks and clinical performance was assessed using the Norris scale. To evaluate dysarthria we developed a computer-based acoustic method. All patients had computer-analysed speech sound tests done three times. The most significantly affected vowels were selected for further studies. A method based on the Euclidian principle was used and the results were compared with 30 age, sex-matched, healthy control subjects. Our results demonstrated the existence of a specific dysarthria profile in ALS patients with most significantly affected vowels: 'B', 'O', 'I', 'W', 'T' in the bulbar group, and: 'B', 'I', 'T', 'W', 'O' in the limb group. This study suggests that it is possible to detect and monitor the progression of the disease based on the acoustic analysis of only several sounds. Abnormalities detected in the dysarthria profile may appear prior to any clinical symptoms of the disease.

Soluble intercelluar adhesion molecule-1, E-selectin, vascular cell adhesion molecule-1 and von Willebrand factor in stroke

We investigated the role of endothelial cell and leukocyte adhesion in the pathophysiology of acute stroke. The immunocytochemical expression of adhesion molecules in brain tissue from six patients who died following acute ischaemic stroke showed weak endothelial expression of intercellular adhesion molecule-1 (ICAM-1), but intense expression of vascular cell adhesion molecule-1 (VCAM-1) by astrocytes and endothelial cells from the infarcted, but not the non-infarcted areas. We also measured soluble adhesion molecules E-selectin, ICAM-1, VCAM-1 and von Willebrand factor (all by enzyme-linked immunosorbent assay) in 21 patients after an acute ischaemic stroke (ictus < 12 h), and again 3 months later. Blood levels in the stroke patients were compared with 82 healthy controls and 22 subjects with carotid atherosclerosis. Compared with healthy controls, both patient groups had raised levels of von Willebrand factor (P < 0.02) but the level of soluble VCAM-1 was raised only in patients with acute stroke (P < 0.02). Levels of von Willebrand factor and soluble VCAM-1 in the stroke patients were still high at 3 months follow-up. We suggest that there might be changes in adhesion molecule expression and release in the acute and chronic stages of ischaemic stroke, where blood levels are related to immunocytochemical findings on infarcted brain. These changes may perhaps be part of the complex pathophysiological responses to infarction and repair of brain tissue following stroke.

Inducible nitric oxide production and expression of transforming growth factor-beta1 in serum and CSF after cerebral ischaemic stroke in man

A residual blood supply to the ischaemic brain is a crucial determinant for tissue survival. Early changes in the vascular network and subsequent angiogenesis may be mediated by short-lived molecules like nitric oxide (NO) or growth factors such as transforming growth factor-beta1 (TGF-beta1). Although TGF-beta1 can inhibit NO production, this interaction has not been studied after ischaemia in humans. Serum samples were taken from patients at 24 h and 6 months and cerebrospinal fluid (CSF) samples at 24 h and 1 week later for possible correlation between the two factors. Tissue expression of TGF-beta1 and of the inducible isoform of NO synthase (NOS2) was assessed by immunohistochemistry. CSF levels of NO2-/NO3- as well as total (active + latent) TGF-beta1 were higher in stroke patients as compared to controls 24 h after the stroke. Both NO2-/NO3- and TGF-beta1 were lower 6 months after the stroke compared to 24 h. Levels of NO2-/NO3- correlated with levels of TGF-beta1 within the time points (P = 0.041, Kendall correlation coefficient). There was a strong staining for NOS2 in brain tissue sections in neurones, reactive astrocytes, infiltrating white blood cells, and endothelial cells of larger microvessels. TGF-beta1 expression was mainly limited to neurones and reactive astrocytes. These findings suggest that the interaction between TGF-beta1 and NOS2 might be important for angiogenesis after cerebral ischaemia and may indicate that TGF-beta1 is upregulated as a negative feedback response to elevated levels of NO.

Vascular endothelial growth factor and its receptor, KDR, in human brain tissue after ischemic stroke

Ischemic stroke results from a reduction in cerebral blood flow to a focal region of the brain after the occlusion of an artery, causing damage to nervous tissue. There is a region of cerebral ischemic tissue (penumbra) surrounding an acute cerebral infarct that is dysfunctional but potentially viable. Restoration of perfusion in the penumbra may ameliorate the tissue damage. The identity and the role of growth factors that control the extent of tissue damage and its repair are poorly understood. Angiogenesis has been demonstrated to occur in brain tissues of patients surviving an acute ischemic stroke. In this paper we have investigated the status of a potent angiogenesis factor, vascular endothelial growth factor (VEGF), in patients after acute ischemic brain stroke. Western blotting and immunohistochemistry were used to determine protein expression, and in situ hybridization was used to quantify and localize mRNA synthesis. The expression of VEGF protein was increased in the penumbra compared with infarcted brain and contralateral hemisphere. Neurones, endothelial cells, and astrocytes in the penumbra in all patients studied had significant up-regulation of both VEGF165 and VEGF189 mRNA (p < 0.01, Wilcoxon Matched-Pairs Signed-Ranks Test) compared with infarcted tissue and the normal looking contralateral hemisphere that was used as a control. Immunohistochemistry demonstrated that kinase insert domain receptor was present in blood vessels within the infarct/penumbra and absent from the normal contralateral hemisphere. VEGF, which is important in angiogenesis, may also influence long term neuronal survival, and possibly its modulation may prove to be of therapeutic value for patients with ischemic stroke.

Genetic resistance to gastrointestinal nematode parasites in Polish long-wool sheep

A study was undertaken from 1991 to 1994 on a farm in southern Poland to evaluate the genetic parameters of resistance to gastrointestinal nematodes. The predominant species were Teladorsagia circumcincta and Haemonchus contortus. A total of 32 sires were evaluated, around 15 per year. Faecal egg counts were measured twice during the 4-month grazing season for lambs (total 659 lambs) and three times for their mothers (total 327 ewes). Infection levels were high during the first 2 years and low during the last 2 years. Using an animal model, the heritability of log10(epg+25) increased from 0.20 in August to 0.33 in September for lambs, and from 0.18 in May to 0.25 in September for ewes. The repeatability of ewe faecal egg count between years was 0.25. A genetic correlation of 0.58 was found between faecal egg count in ewes and in 6-7-month-old lambs. A negative genetic correlation (-0.61) was estimated between faecal egg count in September and daily weight gain of lambs from 70 days of age to the end of grazing season (7 months of age). The results confirm the feasibility of genetic selection of sheep for resistance to nematode parasites in an environment where T. circumcincta and H. contortus are the dominant species.

Angiogenic oligosaccharides of hyaluronan induce protein tyrosine kinase activity in endothelial cells and activate a cytoplasmic signal transduction pathway resulting in proliferation

We have recently shown that the degradation products of hyaluronan of 3 to 10 disaccharides (o-HA), but not native high molecular weight hyaluronan, can induce angiogenesis in vivo and, as such, o-HA is an important regulator of the neovascularization process. As a continuation of this work, we have studied the cytoplasmic signal transduction pathways responsible for o-HA-activated endothelial cell proliferation. We show that the addition of o-HA (1 microg/ml) to bovine aortic endothelial cells induces tyrosine phosphorylation of multiple proteins within 1 minute and that the activity remains above basal levels for at least 24 hours. Increased phosphorylation of the CD44 receptor was also observed. Pretreatment of cells with an anti-CD44-receptor antibody (5 microg/ml) or the tyrosine kinase inhibitor genistein (10 microM) inhibited both o-HA-induced proliferation (p < 0.05) and protein tyrosine phosphorylation. In comparison, native hyaluronan had little effect on tyrosine phosphorylation across the same time period. Protein kinase C (PKC) activity was increased 2- to 3-fold in the membranes of cells treated with o-HA, and a pretreatment with phorbol 12,13-dibutyrate (PDBu) to down-regulate PKC significantly inhibited o-HA-induced cell proliferation (p < 0.05). Examination by Western blotting showed that only the betaI and epsilon isoforms remained translocated to the membrane for at least 24 hours. These isoforms seem to be involved in modulating the proliferative effects of o-HA, because the transient translocation of PKC isoforms by PDBu was not sufficient to induce mitogenesis. Furthermore, we show that PKC activation of the cytoplasmic kinase cascade (Raf-1 kinase, MAP kinase kinase [MEK-1], and extracellular signal-regulated kinase [ERK-1]) by o-HA culminated in the nuclear translocation of ERK-1. This pathway is essentially linear, as shown by the ability of specific enzyme inhibitors (PDBu and PD98059) to prevent both activation of ERK-1- and o-HA-induced proliferation. We conclude that phosphorylation of the CD44 receptor results in an increase in tyrosine phosphorylation, leading to the activation of a cytoplasmic cascade and cell proliferation; this concurs with previous work, which showed that o-HA-induced proliferation of endothelial cells is CD44-receptor-mediated and accompanied by early response gene activation.

CREB (cAMP response element-binding protein) in the locus coeruleus: biochemical, physiological, and behavioral evidence for a role in opiate dependence

Chronic morphine administration increases levels of adenylyl cyclase and cAMP-dependent protein kinase (PKA) activity in the locus coeruleus (LC), which contributes to the severalfold activation of LC neurons that occurs during opiate withdrawal. A role for the transcription factor cAMP response element-binding protein (CREB) in mediating the opiate-induced upregulation of the cAMP pathway has been suggested, but direct evidence is lacking. In the present study, we first demonstrated that the morphine-induced increases in adenylyl cyclase and PKA activity in the LC are associated with selective increases in levels of immunoreactivity of types I and VIII adenylyl cyclase and of the catalytic and type II regulatory subunits of PKA. We next used antisense oligonucleotides directed against CREB to study the role of this transcription factor in mediating these effects. Infusion (5 d) of CREB antisense oligonucleotide directly into the LC significantly reduced levels of CREB immunoreactivity. This effect was sequence-specific and not associated with detectable toxicity. CREB antisense oligonucleotide infusions completely blocked the morphine-induced upregulation of type VIII adenylyl cyclase but not of PKA. The infusions also blocked the morphine-induced upregulation of tyrosine hydroxylase but not of Gialpha, two other proteins induced in the LC by chronic morphine treatment. Electrophysiological studies revealed that intra-LC antisense oligonucleotide infusions completely prevented the morphine-induced increase in spontaneous firing rates of LC neurons in brain slices. This blockade was completely reversed by addition of 8-bromo-cAMP (which activates PKA) but not by addition of forskolin (which activates adenylyl cyclase). Intra-LC infusions of CREB antisense oligonucleotide also reduced the development of physical dependence to opiates, based on attenuation of opiate withdrawal. Together, these findings provide the first direct evidence that CREB mediates the morphine-induced upregulation of specific components of the cAMP pathway in the LC that contribute to physical opiate dependence.

Isozyme-dependent sensitivity of adenylyl cyclases to P-site-mediated inhibition by adenine nucleosides and nucleoside 3'-polyphosphates

Recombinant adenylyl cyclase isozyme Types I, II, VI, VII, and three splice variants of Type VIII were compared for their sensitivity to P-site-mediated inhibition by several adenine nucleoside derivatives and by the family of recently synthesized adenine nucleoside 3'-polyphosphates (Désaubry, L., Shoshani, I., and Johnson, R. A. (1996) J. Biol. Chem. 271, 14028-14034). Inhibitory potencies were dependent on isozyme type, the mode of activation of the respective isozymes, and on P-site ligand. For the nucleoside derivatives potency typically followed the order 2',5'-dideoxyadenosine (2',5'-ddAdo) > beta-adenosine > 9-(cyclopentyl)-adenine (9-CP-Ade) >/= 9-(tetrahydrofuryl)-adenine (9-THF-Ade; SQ 22,536), with the exception of Type II adenylyl cyclase, which was essentially insensitive to inhibition by 9-CP-Ade. For the adenine nucleoside 3'-polyphosphates inhibitory potency followed the order Ado < 2'-dAdo < 2',5'-ddAdo and 3'-mono- < 3'-di- < 3'-triphosphate. Differences in potency of these ligands were noted between isozymes. The most potent ligand was 2',5'-dd-3'-ATP with IC50 values of 40-300 nM. The data demonstrate isozyme selectivity for some ligands, suggesting the possibility of isozyme-selective inhibitors to take advantage of differences in P-site domains among adenylyl cyclase isozymes. Differential expression of adenylyl cyclase isozymes may dictate the physiological sensitivity and hence importance of this regulatory mechanism in different cells or tissues.

A putative role for platelet-derived growth factor in angiogenesis and neuroprotection after ischemic stroke in humans

BACKGROUND AND PURPOSE

Growth factors control two important processes in infarcted tissue, ie, angiogenesis and gliosis. We recently reported that transforming growth factor-beta1 (TGF-beta1) might be involved in angiogenesis after ischemic stroke in humans; here we present data of an extensive study on platelet-derived growth factor (PDGF) and its receptors.

METHODS

We studied brain samples from patients who suffered from ischemic stroke for the expression of mRNA encoding PDGF-A, PDGF-B, and PDGF receptors (PDGF-R). Proteins were examined by Western blotting and immunohistochemistry using the antibodies to PDGF-AB, PDGF-BB, PDGF-R alpha, and PDGF-R beta.

RESULTS

At the mRNA level, PDGF-A and PDGF-B were expressed mainly in neurons in penumbra. PDGF-R mRNA was strongly expressed in some astrocytes but mainly in type III/IV neurons in infarct and penumbra. The least expression was seen in the contralateral hemisphere (P<.001). In contrast, both PDGF-AB and PDGF-BB immunoreactive products were present in most cell types: PDGF-R alpha and PDGF-R beta mainly on neurons, and PDGF-R beta on some endothelial cells, with less staining of all the isoforms in the contralateral hemisphere. On Western blots, PDGF-AB and -BB were expressed more within white matter than gray matter of infarct/penumbra, whereas both isoforms of receptor were expressed mainly in gray matter compared with contralateral hemisphere. There was no or very weak expression of the receptor in white matter.

CONCLUSIONS

PDGF proteins are highly expressed in white matter, suggesting that PDGF may exert its function in white matter participating either in regeneration of damaged axons or in glial scar formation. PDGF-BB and its receptor expressed on microvessel endothelial cells might be involved in angiogenesis after stroke. Thus, PDGF is likely to be angiogenic and neuroprotective in stroke.

The use of factor analysis for ascertaining patterns of psychopathology in children with intellectual disability

The Developmental Behaviour Checklist (DBC) was developed to assess psychopathology in children with intellectual disabilities. A cut-off point between "non-cases' and "cases' was determined by comparison of the total scores with psychiatric clinical assessment. This paper describes a method aimed at determining the types of psychiatric problems in those regarded as "cases'. Factor analysis with varimax rotation carried out on a sample of 1093 subjects extracted six factors. Standardized factor scores were calculated for each subject in a community sample (n = 450), and the only or the dominant positive score was determined for each of the "cases'. Over 80% of "cases' could be allotted to one condition. Only a small number had none, or three or more conditions. The same procedure was replicated on a validation sample (n = 448) with even more satisfactory results. Differences in the prevalence of the six conditions by sex, age and level of mental retardation were ascertained. The validity and clinical relevance of this method are discussed.

Increased expression of TGF-beta 1 in brain tissue after ischemic stroke in humans

BACKGROUND AND PURPOSE

Occlusion in cerebral vessels results in ischemic stroke and is followed by proliferation of microvessels, ie, angiogenesis. The process is particularly marked in the border zone of the infarct, known as the ischemic penumbra. This increase in vascularization is likely to be caused by the action of angiogenic factors, such as TGF-beta 1, which is a powerful regulator of angiogenesis.

METHODS

In this study we examined 10 brain samples from patients who suffered from ischemic stroke for the expression of mRNA encoding TGF-beta 1.

RESULTS

The ischemic penumbra contained the highest levels of TGF-beta 1 mRNA, whereas the normal contralateral hemispheres had the least (P < .001, Mann-Whitney U test). Unlike those from normal brain, protein extracts from infarcted tissue contained active TGF-beta 1 as a 25-kD band in Western blot analysis. Extracts from the penumbra also contained a 12.5-kD isoform of TGF-beta 1. Both penumbra and infarct contained TGF-beta 1 immunoreactive products as assessed with immunohistochemistry, whereas very weak staining was observed in the contralateral hemisphere.

CONCLUSIONS

These results suggest that TGF-beta 1 is important in the pathogenesis of the angiogenic response in ischemic brain tissue and its modulation may be used for therapeutic purposes.

Splice variants of type VIII adenylyl cyclase. Differences in glycosylation and regulation by Ca2+/calmodulin

Three alternatively spliced type VIII adenylyl cyclase messages have been identified by cDNA cloning and amplification from rat brain cDNA. Type VIII-A was previously referred to simply as type VIII (Cali, J. J., Zwaagstra, J. C., Mons, N., Cooper, D. M. F., and Krupinski, J. (1994) J. Biol. Chem. 269, 12190-12195). The types VIII-B and -C cDNAs differ from that of type VIII-A by deletion of 90 and 198 base pair exons, respectively, which encode a 30-amino acid extracellular domain with two consensus sites for N-linked glycosylation and a 66-amino acid cytoplasmic domain. Stable expression of types VIII-A, -B, and -C cDNAs in human embryonal kidney 293 (HEK-293) cells leads to the appearance of novel proteins, which are recognized by type VIII-specific antibodies and which co-migrate with immunoreactive species detected on immunoblots of rat brain membranes. Types VIII-A and -C are modified by N-linked glycosylation, while type VIII-B is insensitive to treatment with N-glycosidase F. An influx of extracellular Ca2+ stimulates cAMP accumulation in HEK-293 cells stably expressing type VIII-A, -B, or -C, but not in control cells. Adenylyl cyclase activity of each of the variants is stimulated by Ca2+/calmodulin and the EC50 for activation of type VIII-C is one fourth of that for either type VIII-A or -B. Type VIII-C also has a distinct Km for substrate, which is approximately 4-12-fold higher than that for types VIII-A or -B depending on whether Mn2+ or Mg2+ is the counterion for ATP. The differences in the structural and enzymatic properties of these three variants are discussed.