The combination of homozygous MTHFR 677T and angiotensin II type-1 receptor 1166C variants confers the risk of small-vessel-associated ischemic stroke.

Previous studies have suggested that both angiotensin II type-1 receptor (AT1R) 1166C and methylenetetrahydrofolate reductase (MTHFR) 677T variants can have disadvantageous effects on the small-vessel circulation under certain conditions. The purpose of this study was to analyze the possible consequences of the simultaneous distribution of these two genetic variants in different types of ischemic stroke. The genetic and clinical data on 357 ischemic stroke patients and 263 control subjects were analyzed by using univariate and logistic statistical approaches. Neither the MTHFR 677T nor the AT1R 1166C genetic variant alone conferred the risk of any subtype of ischemic stroke. The combination of the homozygous MTHFR 677TT genotype and at least one AT1R 1166C allele occurred more frequently in the ischemic stroke patients (8.68%) than in the controls (4.56%, p < 0.05). Specific subclassification of the patients revealed an accumulation of this combination in small-vessel-associated ischemic stroke (12.2%, p < 0.01); multivariate logistic regression analysis of the data confirmed this association, with an odds ratio of 2.66 (95% confidence interval, 1.28-7.89; p < 0.05). These findings suggest that the combination of these two genetic factors can contribute to the development of small-vessel cerebral infarcts. Although the exact mechanism of action is not known, addition of the unfavourable effects on the endothelial function can be presumed.

Cell and small animal models for phenotypic drug discovery.

The phenotype-based drug discovery (PDD) approach is re-emerging as an alternative platform for drug discovery. This review provides an overview of the various model systems and technical advances in imaging and image analyses that strengthen the PDD platform. In PDD screens, compounds of therapeutic value are identified based on the phenotypic perturbations produced irrespective of target(s) or mechanism of action. In this article, examples of phenotypic changes that can be detected and quantified with relative ease in a cell-based setup are discussed. In addition, a higher order of PDD screening setup using small animal models is also explored. As PDD screens integrate physiology and multiple signaling mechanisms during the screening process, the identified hits have higher biomedical applicability. Taken together, this review highlights the advantages gained by adopting a PDD approach in drug discovery. Such a PDD platform can complement target-based systems that are currently in practice to accelerate drug discovery.

Coexistence of angiotensin II type-1 receptor A1166C and angiotensin-converting enzyme D/D polymorphism suggests susceptibility for small-vessel-associated ischemic stroke.

The renin-angiotensin system plays an important role in the maintenance of blood pressure homeostasis. The angiotensin-converting enzyme (ACE) converts angiotensin I into angiotensin II. Angiotensin II, which binds the angiotensin II type-1 receptor (AT1R), is a potent vasoconstrictor. On a pathophysiological basis, both ACE I/D and AT1R A1166C polymorphism lead to an enhanced activity of the angiotensin II-AT1R axis, thereby possibly contributing to circulatory disturbances. A mutually facilitatory effect may be presumed between the two polymorphisms. We examined whether this synergistic effect is involved in the evolution of different types of ischemic stroke. Genetic and clinical data on 308 consecutive patients with acutely developing ischemic stroke were analyzed. Atotal of 272 stroke and neuroimaging alteration-free subjects served as a control group. Univariate and logistic regression statistical approaches were used. The ACE D allele combined with the AT1R 1166C allele did not yield a risk of ischemic stroke. However, the co-occurrence of the homozygous ACE D/D and at least one AT1R 1166C allele was more frequent in the ischemic stroke group than in the control group (22.4 vs 11%, p < 0.005, OR, 2.33; 95% CI, 1.46-3.7). After specific subgroup analysis, this synergistic association was even stronger for small-vessel ischemic stroke (OR, 3.44; 95% CI, 1.9-6.24; p < 0.0005). Multivariate logistic regression analysis of the data confirmed this association (adjusted OR, 3.54, 95% CI, 1.88-7.16; p < 0.0005). Our results demonstrate that ACE D/D and AT1R 1166C polymorphism were associated with the development of small-vessel ischemic stroke through a mutually facilitatory interplay between them. Genetic interactions might contribute to the altered functional network in renin-angiotensin system in vascular disorders.

Angiotensin II type-1 receptor A1166C polymorphism is associated with increased risk of ischemic stroke in hypertensive smokers.

Recent observations revealed a novel role of angiotensin-converting enzyme 2 and the angiotensin II type-1 receptor (AT1R) in lung injury, thereby extending knowledge about the functions of the angiotensin system. Angiotensin II, whose target is the AT1R, is a potent vasoconstrictor. Accordingly, an imbalance leading to enhanced activity of the angiotensin II-AT1R axis is postulated to contribute to both circulatory disturbances and lung injury. In this context, a functional single-nucleotide polymorphism, AT1R A1166C, which leads to enhanced responsiveness of the AT1R, has been postulated as a candidate susceptibility factor for ischemic stroke. The aim of our study was to investigate its occurrence in ischemic stroke and to analyze its possible synergistic associations with clinical risk factors. Genetic and clinical data on 308 consecutive patients with acutely developing ischemic stroke were analyzed. A total of 272 stroke and neuroimaging alteration-free subjects served as a control group. Univariate and logistic regression statistical approaches were used. Alone, the AT1R 1166C allele did not pose a risk of stroke. In hypertensive smokers, however, it was associated with an increased risk of ischemic stroke (OR 22.3, 95% CI 5.8-110.2, p<0.001). Further subgroup analysis revealed the same association for both small-vessel (OR 24.3, 95% CI 6.1-121.1, p<0.001) and large-vessel (OR 21.3, 95% CI 4.6-81.1, p<0.001) infarction. On a pathophysiological basis, our results suggest the possibility that the AT1R A1166C polymorphism might give rise to ischemic stroke indirectly via an unfavorable effect on the cardiorespiratory function.

Apolipoprotein A5 gene promoter region T-1131C polymorphism associates with elevated circulating triglyceride levels and confers susceptibility for development of ischemic stroke.

The possible pathogenic role of triglycerides (TG) in the development of ischemic stroke is still under extensive investigation. Recently, apolipoprotein (apo)A5 gene promoter region T-1131C polymorphism has been shown to associate with elevated serum TG levels. In the current work, a total of 302 subjects were classified as being large vessel-associated, small vessel-associated, or belonging to a mixed group of ischemic stroke-affected patients. The level of TG was increased in all groups (p < 0.01). The apoA5-1131C allele frequency was approximately twofold in all groups of stroke patients compared with the controls (5 vs 10-12%; p < 0.05); and the apoA5-1131C allele itself was also found to associate with increased TG levels in all groups. In a multivariate logistic regression analysis model adjusted for differences in age, gender, serum cholesterol, hypertension, presence of diabetes mellitus, smoking and drinking habits, and ischemic heart disease, a significantly increased risk of developing stroke disease was found in patients carrying the apoA5-1131C allele (p < 0.05; odds ratio OR = 2.1 [1.3-4.7]); this association was also proven for all subtypes of the stroke. The results presented here suggest that the apoA5-1131C allele is an independent risk factor for the development of stroke. Being that apoA5 gene is under the control of the peroxisome proliferator-activated receptor alpha, theoretically, the current observations also can have long-term therapeutic consequences.

[Interactions between the MTHFR C677T and MTHFR A1298C mutations in ischaemic stroke]. / A metiléntetrahidrofolsav-reduktáz gén C677T- es A1298C-mutációinak interakciója ischaemiás stroke-ban.

INTRODUCTION: Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C mutations, being considered unfavourable genetic factors by causing elevated serum homocysteine levels, may be risk factors for cardiovascular disorders, including ischaemic stroke. In this study, the role of these two mutations in ischaemic stroke was examined: PATIENTS AND METHODS: Genetic and clinical data were analysed of 122 ischaemic stroke patients and 102 control subjects with no lesions by neuroimaging. RESULTS: Neither of the two MTHFR mutations alone was found to be a significant genetic risk factor for ischaemic stroke. However, at least one MTHFR 677T allele combined with at least one MTHFR 1298C allele significantly increased the risk of ischaemic stroke (adjusted odds ratio: 3.39; p < 0.001). CONCLUSION: The synergistic effect between the two MTHFR mutations may represent a new genetic stoke risk factor.

Lymphotoxin-alpha gene 252G allelic variant is a risk factor for large-vessel-associated ischemic stroke.

A direct role of lymphotoxin-alpha (LTA) in promoting atherosclerotic plaque growth has been demonstrated recently. The different protein transcripts of the naturally occurring genetic variants of the LTA gene have been demonstrated to exhibit affected functions, and an allelic difference in binding to transcription factor(s) has also been suggested. The homozygous variant of LTA characterized by the intron 1 252A-->G (252G) transition, which naturally coexists with an exon 3 804C-->A (804A) single-nucleotide polymorphism (SNP), has been reported as a susceptibility gene for myocardial infarction. Because the atherosclerotic process is also an integral component in the pathogenesis of certain types of vascular stroke, we investigated the possible significance of the above SNPs in 353 ischemic stroke patients and 180 healthy controls. The homozygous LTA allele with the 252G and 804C SNPs occurred more frequently in stroke patients (13.9%) than in controls (7.20%, p<0.025). Specific subclassification of the patients revealed an accumulation of these SNPs in large-vessel, pathology-associated cerebral infarction (18.2%); multivariate logistic regression analysis of the data confirmed this association, with an odds ratio of 2.1 (95% confidence interval, 1.3-6.2; p<0.005). Elimination of all subjects with a history or evidence of ischemic heart disease, including myocardial infarction, did not affect this association. These data show that besides the role in the development of myocardial infarction, the homozygous carriage of the LTA allele with 252G and 804A SNPs is a novel susceptibility factor for largevesselassociated ischemic stroke.

Dose-independent antinociceptive interaction of endogenous ligands at the spinal level.

Adenosine, agmatine and kynurenic acid are endogenous ligands acting on different (e.g. adenosine, NMDA, alpha(2)-adrenergic and imidazoline) receptors with a potential role in nociception at the spinal level. Their antinociceptive effects have already been investigated as monotherapy, but only a few studies have reported on their effects on the potency of other drugs. The purpose of the present study was carried out to analyse their interactions during continuous intrathecal co-administration in a carrageenan-induced thermal hyperalgesia model in rats. A paw withdrawal test was used for nociceptive testing. The intrathecal infusion (60 min) of these three drugs was administered alone or in combinations (kynurenic acid+adenosine or agmatine; adenosine+agmatine), which was followed by an additional 60-min observation period. Kynurenic acid alone was ineffective, while adenosine and agmatine alone caused a slight increase in pain threshold. However, independently of the applied doses all of the combinations significantly (p<0.05) increased the paw withdrawal latencies on the inflamed side during and after the infusion, but were almost ineffective on the normal side. The adenosine+kynurenic acid combination was the most effective: namely, that it relieved thermal hyperalgesia in all the applied dose combinations. Treatment with the kynurenic acid-containing combinations also caused dose-dependent side-effects (motor impairment and excitation), despite the fact that monotherapy with kynurenic acid in the applied dose (0.1 microg/min) did not result in adverse effects.

Evaluation of the interactions of common genetic mutations in stroke subtypes.

OBJECTIVE: Ischemic stroke is a frequent heterogeneous multifactorial disease that is affected by several genetic mutations and environmental factors. We hypothesised the clinical importance of the co-occurrence of common, unfavorable genetic mutations in the development of different stroke subtypes. METHOD AND MATERIAL: The Factor V Leiden G1691A (Leiden V), the prothrombin G20210A and the methylenetetrahydrofolate reductase C677T (MTHFR C677T) mutations and the angiotensin-converting enzyme I/D (ACE I/D) and apolipoprotein E (APOE) genotypes were examined by the PCR technique in 689 ischemic stroke patients and 652 stroke-free controls. Logistic regression models were used to estimate the relative risks of different stroke subtypes for different genotype combination patterns. RESULTS: The ACE D/D genotype alone or in combination with the MTHFR 677T or the APOE 4 allele or with both was highly specific for small-vessel infarction. The Leiden V mutation alone or in different combination patterns with the ACE D, APOE 4 and MTHFR 677T alleles was specifically predisposed to large-vessel infarction. The APOE 4 allele alone was calculated to be a general, minor genetic risk factor for ischemic stroke. The MTHFR 677T allele alone was not a risk factor for any stroke subtype. In the different specific predisposition gene combinations, however, both the APOE 4 and MTHFR 677T alleles could increase the relative risk of the given stroke subgroup. CONCLUSIONS: Common mutations which alone are minor or non-significant risk factors for ischemic stroke can yield, in specific combination patterns, a highly significant, moderate genetic risk of specific stroke subtypes.

Increased prevalence of platelet glycoprotein IIb/IIIa PLA2 allele in ischaemic stroke associated with large vessel pathology.

INTRODUCTION: Platelet glycoprotein IIb/IIIa is a membrane receptor with a central function in the platelet adhesion and ultimately in the thrombus formation. Two major variants of the gene encoding the IIIa subunit, called PLA1 (A1) and PLA2 (A2), have been identified in the general population. There are indications that the A2 allele can also be associated with acute thrombosis or stroke. The purpose of this study was to study the distribution of the A2 allele in different vascular subtypes of stroke disease. MATERIALS AND METHODS: A total of 638 consecutive patients were analyzed and classified as having large vessel pathology (n=168) or a small vessel infarct (n=210). Localization of the vascular occlusions was deducted from analysis of the magnetic resonance imaging (MRI) scan results in stroke patients. The remainder patients were listed into a mixed vascular pathology group (n=167). Patients with other or poorly characterized stroke etiology were excluded from the study (n=93). RESULTS: In the small vessel and mixed vascular pathology groups, the PLA2 allele frequency was similar to that in the controls. By contrast, PLA2 allele frequency was approximately two-fold higher in patients with large vessel pathology (23.3%) than in the stroke-free control subjects (11.7%, p<0.0005). Multivariate logistic regression analysis of data confirmed this association with an odds ratio (OR) of 2.9 (95% confidence interval [CI]: 1.6-4.9, p<0.0005). CONCLUSIONS: These data suggest that the PLA2 allele is more frequent in brain infarcts associated with large-vessel occlusion.

[Two cases of frontotemporal dementia]. / A frontotemporalis dementiákról két eset kapcsán.

Frontotemporal dementias represent the third most common cause of primer degenerative dementias next to Alzheimer's disease and Lewy body disease. Frontotemporal dementia constitutes 10-20% of all praesenilis dementias. The authors present the results of the 10 years' clinical, neuropsychological, neuropathological examinations and brain imaging with the examples of two cases. At the early stage of frontotemporal dementia changes of personality and social conduct are prominent, whereas cognitive functions are relatively well preserved. The usual dementia tests are not sufficiently sensitive to disclose non-cognitive symptoms. Clinical diagnosis as well as differentiation from functional psychiatric disorders can be difficult. Brain imaging present the frontal and the anterior temporal lobe atrophy and selective hypometabolism in these areas. The typical onset is between at the age 50 and 65 years. It is very rare under the age of 30. The symptoms of two patients started at the age of 42-44. The first diagnosis was post traumatic stress disorder. Later stereotyped behaviour, mental rigidity, hyperorality, irritability, progressive reduction of speech and vegetative dysfunctions appeared. Besides the affecting of the irresistibly worsening symptoms and the medical care requiring strength and inventiveness, the authentic informing of the relatives is also a challenge. The caregivers have special relationship with the patients and their relatives.

Quantitative characterization of a repeated acute joint inflammation model in rats.

1. Chronic pain owing to arthritis is a major clinical problem worldwide. To study the underlying pathological mechanisms of chronic pain and the effectiveness of different treatments, a number of experimental models have been developed over the years. 2. We introduced a new subchronic inflammatory model by repeated unilateral administration of carrageenan into the ankle joint of rats, and investigated the degree and the time-course of the oedema, and thermal and mechanical hyperalgesia. 3. Carrageenan (450 microg) was injected on three occasions (on days 1, 4 and 7), and the resulting oedema, thermal hyperalgesia (paw withdrawal test) and weight load were characterized in voluntarily walking rats daily for 15 days. The effect of diclofenac sodium (3 mg/kg orally daily for 15 days) was also determined. 4. Repetitive administration of carrageenan caused fluctuating oedema and pain responses, which did not normalize within 3 days. Exacerbated inflammatory oedema was observed after the second and third injections. Oedema and a decreased weight load of the inflamed paw were observed throughout the investigation period, and paw withdrawal thresholds to noxious thermal stimuli returned to baseline pre-carrageenan values from Day 13. 5. Oral diclofenac (3 mg/kg daily for 15 days) significantly decreased oedema within a few days (Day 3), whereas its anti-allodynic effect developed only several days later (Day 9). However, diclofenac at the applied dose did not influence the thermal hyperalgesia. 6. The results suggest that the repeated administration of carrageenan might be a suitable model for determining the effects of long-lasting treatment.