Frequencies of polymorphisms in CYP2C9 and VKORC1 genes influencing warfarin metabolism in Slovak population: implication for clinical practice

OBJECTIVES

The study was aimed at establishing an effective molecular-genetic method for detecting polymorphisms in genes CYP2C9 and VKORC1, which affect the pharmacogenetics of warfarin, and at determining their prevalence in Slovak population.

BACKGROUND

Warfarin, derivative of coumarin, belongs to the most commonly prescribed oral anticoagulants with narrow therapeutic index. An insufficient dose of warfarin can result in failure to produce the antithrombotic effect, whereas an overdose increases the risk of bleeding. It was proven that genetic variability in two genes, CYP2C9 a VKORC1, has a significant influence on the individual's response to the dosage of warfarin.

METHODS

In a control group of 112 randomly selected individuals, we tested the frequency of selected single nucleotide polymorphisms including CYP2C9*2 (430C>T), CYP2C9*3 (1075A>C), VKORC1*2 (1173C>T) by allele-specific Real-Time PCR and VKORC1*2 (-1639G>A) by using PCR-RFLP.

RESULTS

Due to the combination of frequent alleles CYP2C9*2, CYP2C9*3 and VKORC1*2 in Slovak population we determine that 25% of population need a standard 5-mg daily dose of warfarin, while 44%, 23%, and 8% need 4 mg, 3 mg and 2 mg of warfarin per day.

CONCLUSION

Slovak population is in Hardy-Weinberg equilibrium and frequencies of SNPs were in accordance with other published results in European populations (Tab. 5. Fig. 3, Ref. 51).

Optical coherence tomography and its use in optical neuritis and multiple sclerosis

Optical coherence tomography is a relatively new non-invasive imaging technique used for obtaining the images and quantifying the layers of the retina. It also provides information about optic nerve head topography, peripapillary retinal nerve fiber layer thickness, and macular volume which correlates with axonal loss. Until now, this method was used mainly in ophthalmology; now it has emerged as relevant in neurology as well. RNFL thickness is of particular interest in optic neuropathies and in multiple sclerosis. In sclerosis multiplex, axonal loss occurs as early as the first stages and the quantification of the RNFL thickness by OCT provides an indirect measure of axonal and neuronal loss in the anterior visual pathways. Because OCT is noninvasive, easy to obtain, and highly reproducible, it can be used as a marker of axonal loss and as an endpoint in clinical trials. This paper presents a comprehensive summary of the use of this new diagnostic method in multiple sclerosis patients (Fig. 1, Ref. 58).

Clinical accuracy of the distinction between Alzheimer's disease and frontotemporal lobar degeneration

Alzheimer's disease (AD) is the most common cause of dementia. Frontotemporal lobar degeneration (FTLD), although less prevalent overall, is almost as common as AD in patients under the age of 65. AD and FTLD are histopathologically distinct, with AD being characterised by extracellular amyloid plaques and intraneuronal neurofibrillary tangles, and FTLD by the presence of non-AD histological pathology, most commonly either tau-positive inclusions or ubiquitin-positive or TDP 43 positive inclusions. Clinically, AD and FTLD may occur with overlapping symptoms, especially in the early stages of the disease. In the case of Alzheimer's disease, it is represented by isolated decline of recent episodic memory; later on, by the impairment of time and space orientation, whereby the alteration of social behaviour and amnesic aphasia occur predominantly in the advanced phases of the disease. Frontotemporal lobar degeneration is demonstrated in three clinical subunits: 1) The behavioural-dysexecutive variant of FTLD (frontotemporal dementia, the frontal variant of FTLD, {fvFTLD}), 2) Progressive non-fluent aphasia, 3) Semantic dementia (SD) with the profound impairment of social conduct (fvFTLD) or with severe speech impairment (PNFA, SD). Considering the different clinical symptomatology with FTLD diagnostics, it is necessary to use different psychometric tests than in the case of Alzheimer's disease. Therapy and the degree of dependence of the affected person are also different. All three diseases within the FTLD category, mainly the behavioural-dysexecutive variant, require a higher level of nursing care on the part of other persons or institutions in comparison with Alzheimer's disease. The goal of our publication is to point to the differences in clinical manifestation and the findings of auxiliary examinations that are helpful in the clinical accuracy of the distinction between these two types of dementia (Tab. 1, Fig. 3, Ref. 18).

Predictors of impaired endothelial function in obstructive sleep apnea syndrome

OBJECTIVES

Obstructive sleep apnea syndrome (OSA) is associated with increased cardiovascular morbidity and mortality. Endothelial dysfunction (ED), accelerated atherosclerosis and autonomic dysfunction might be the key players responsible for development of vascular diseases in patients with OSA. In a population with suspected OSA and low burden of cardiovascular risk factors, we therefore aimed to investigate the association between potential cardiovascular risk factors including OSA-specific indices, ED and autonomic activity.

METHODS

ED was investigated using reperfusion hyperaemia index (RHI). OSA was assessed using standard polysomnography, autonomic activity was assessed using baroreflex sensitivity (BRS).

RESULTS

We enrolled 31 patients (42.1±11.7 years) with OSA. Significant inverse correlation was found between RHI and apnea-hypopnea index (AHI) (r=-0.550, p=0.001) and between RHI desaturation index (r=-0.533, p=0.002). Positive correlation was found between RHI and minimal nocturnal oxygen saturation (r=0.394, p=0.028). In a multiple regression model AHI was the only significant variable to predict RHI (β=-0.522, p=0.003). We found no correlation between RHI and BRS. RHI in the population with severe OSA (AHI above 30) was significantly lower than RHI in the rest of the population (p=0.012).

CONCLUSION

AHI was the only significant independent predictor of impaired endothelial function as expressed by RHI. RHI showed no association with BRS in patients with OSA.

Recommendations for the use of prolonged-release fampridine in patients with multiple sclerosis (MS)

Prolonged-release fampridine (fampridine PR) is a potassium channel blocker that improves conductivity of signal on demyelinated axons in central nervous system. Fampridine PR has been approved to improve speed of walking in patients with multiple sclerosis. This statement provides a brief summary of data on fampridine PR and recommendations on practical use of the medication in clinical practice, prediction, and evaluation of response to treatment and patient management.

Genetic aspects of vitamin D receptor and metabolism in relation to the risk of multiple sclerosis

Recent findings suggest that polymorphisms in vitamin D pathway genes are candidates for association with multiple sclerosis susceptibility. It has been now well demonstrated that vitamin D has immunomodulatory functions that may be favorable for reduction of multiple sclerosis risk. Current research has been focused on identification of new variants of genes involved in vitamin D pathway, namely in vitamin D receptor and enzymes of vitamin D metabolism. These variants have been intensively studied as possible genetic predictors of both vitamin D levels and the risk of multiple sclerosis. Considering the findings available up-to-date, we may recognize two groups of genetic variants. The first group of genes was found to predict vitamin D levels but not the risk of multiple sclerosis. The second group of genetic variants is represented by promising genes predicting vitamin D levels as well as the risk of multiple sclerosis. A strong association with increased risk of the disease has been observed for a rare variant in the CYP27B1 gene encoding a vitamin D-activating enzyme. Observed interaction between genetic and epidemiological findings brings the rationale for supplementation trials of vitamin D. Although promising effects of vitamin D supplementation have emerged, the results obtained so far are inconclusive and the real therapeutic significance of vitamin D supplementation remains to be elucidated.

Stroke care in Central Eastern Europe: current problems and call for action

Stroke is a major medical problem and one of the leading causes of mortality and disability all over in Europe. However, there are significant East-West differences in stroke care as well as in stroke mortality and morbidity rates. Central and Eastern European countries that formerly had centralized and socialist health care systems have serious and similar problems in organizing health and stroke care 20 years after the political transition. In Central and Eastern Europe, stroke is more frequent, the mortality rate is higher, and the victims are younger than in Western Europe. High-risk patients live in worse environmental conditions, and the socioeconomic consequences of stroke further weaken the economic development of these countries. To address these issues, a round table conference was organized. The main aim of this conference was to discuss problems to be solved related to acute and chronic stroke care in Central and Eastern European countries, and also, to exchange ideas on possible solutions. In this article, the discussed problems and possible solutions will be summarized, and introduce 'The Budapest Statement of Stroke Experts of Central and Eastern European countries'.

Baroreflex Sensitivity to Predict Malignant Middle Cerebral Artery Infarction

Background and Purpose—

Hemicraniectomy has been shown to be an effective treatment of life-threatening edema (LTE) in malignant middle cerebral artery infarction when performed early. Identifying patients who will develop LTE is therefore imperative. We hypothesize that autonomic shift toward sympathetic dominance may relate to LTE formation. We aimed to investigate the predictive potential of baroreflex sensitivity (BRS) as a marker of autonomic balance for calculating the course of large middle cerebral artery infarction.

Methods—

Patients with middle cerebral artery infarction >2/3 of the territory and BRS measurement at admission were analyzed. BRS was estimated using the cross-correlational method. Demographic, clinical, and radiological data including stroke severity, infarct size, and basal ganglia involvement were recorded. Malignant course with LTE was defined as clinical deterioration and midline shift ≥5 mm in the first 48 hours.

Results—

Eighteen (62.8%) patients developed LTE. Patients with LTE had lower BRS (2.3 versus 4.4 mm Hg/ms, P =0.007), larger infarcts (214 versus 144 mL, P =0.03), more frequent involvement of the basal ganglia (14 versus 4, P =0.03), and more often underwent thrombolysis combined with endovascular intervention (6 versus 0, P =0.04). In a multivariate model, BRS (OR, 0.36; CI, 0.14–0.93; P =0.03) and basal ganglia involvement (OR, 11.53; CI, 1.15–115.9; P =0.04) were independent predictors for LTE. This model correctly classified 86.2% of the malignant cases.

Conclusions—

Decreased BRS, mirroring sympathetic activation, and basal ganglia involvement were associated with development of malignant course with LTE in large middle cerebral artery infarction. The predictive relevance of our findings needs to be confirmed in further studies.

Autonomic Shift and Increased Susceptibility to Infections After Acute Intracerebral Hemorrhage

Background and Purpose—

High infection rate after severe stroke may partly relate to brain-induced immunodepression syndrome. However, the underlying pathophysiology remains unclear. The aim of the current study was to investigate the role of autonomic shift in increased susceptibility to infection after acute intracerebral hemorrhage (ICH).

Methods—

We retrospectively analyzed 62 selected patients with acute ICH from our prospective database. Autonomic shift was assessed using the cross-correlational baroreflex sensitivity (BRS). The occurrence and cause of in-hospital infections were assessed based on the clinical and laboratory courses. Demographic and clinical data including initial stroke severity, hemorrhage volume, intraventricular blood extension, history of aspiration, and invasive procedures such as mechanical ventilation, surgical hematoma evacuation, external ventricular drainage, central venous and urinary catheters, and nasogastric feeding were recorded and included in the analysis.

Results—

We identified 36 (58%) patients with infection during the first 5 days of hospital stay. Patients with infections had significantly lower BRS, higher initial NIHSS scores, larger hemorrhages, and more frequently had intraventricular blood extension and underwent invasive procedures. In the multivariate regression model, decreased BRS (OR, 0.54; 95% CI, 0.32–0.91; P =0.02) and invasive procedures (OR, 2.32; 95% CI, 1.5–3.6; P <0.001) remained independent predictors for an infection after ICH.

Conclusions—

Decreased BRS was independently associated with infections after ICH. Autonomic shift may play an important role in increased susceptibility to infections after acute brain injury including ICH. The possible therapeutic relevance of autonomic modulation warrants further studies.

Real-life experiences in migraine therapy

OBJECTIVE

To evaluate the effectiveness of eletriptan for acute migraine treatment and patient satisfaction with the drug in usual clinical practice settings.

METHODS

Male and female patients of practicing neurologists, aged 18 to 65 years, were eligible for inclusion in the study if they met International Headache Society criteria for migraine.

RESULTS

Of 637 patients enrolled, 611 completed the study. At 1 hour post-dose headache response was 59.5% (average from three attacks), pain-free 13%, absence of vomiting 86.3%, and improvement in functioning 55%. Headache recurrence occurred in 12%, second dose was used by 12.6% patients, and rescue medication by 6.4%. Patient preference for eletriptan versus any other triptan used in the past was 97%.

CONCLUSION

In this real-life setting, eletriptan displayed high efficacy, consistency of response over three attacks and was preferred by 97% patients (Tab. 2, Fig. 5, Ref. 16). Full Text (Free, PDF) www.bmj.sk.

Baroreflex: a new therapeutic target in human stroke?

BACKGROUND AND PURPOSE

Autonomic dysfunction, including increased sympathetic drive and blunted baroreflex, has repeatedly been observed in acute stroke. Of clinical importance is that the stroke-related autonomic imbalance seems to be linked to worse outcome after stroke. Here, we discuss the role of baroreflex impairment in acute stroke and its possible pathophysiological and therapeutic relevance. Summary of Review- Possible mechanisms linking baroreflex impairment with unfavorable outcome in stroke may include increased cardiovascular morbidity and mortality, promotion of secondary brain injury due to local inflammation, hyperglycemia, or altered cerebral perfusion.

CONCLUSIONS

We suggest therefore that the modifying of autonomic functions may have important therapeutic implications in acute ischemic as well as in hemorrhagic stroke.

Impaired Baroreceptor Reflex Sensitivity in Acute Stroke Is Associated With Insular Involvement, But Not With Carotid Atherosclerosis

Background and Purpose— Impaired baroreflex sensitivity (BRS) has been previously shown to be of prognostic value in patients with cardiovascular disease and stroke. Because baroreflex seems to be blunted by both carotid atherosclerosis and by lesions affecting central processing, controversy exists regarding the etiology of stroke-related baroreflex changes. The insula may play a central role in baroreflex modulation. The aim of the study was therefore to examine BRS in patients with acute stroke with regard to carotid atherosclerosis and insular involvement.

Methods— We evaluated spontaneous BRS in 96 patients with acute stroke within 72 hours of ictus and 41 control subjects using a sequential crosscorrelation method.

Results— Fifty-two patients with ischemic stroke and 44 patients with intracerebral hemorrhage, mean age 58.4 years, were included. With comparable carotid atherosclerosis profiles, patients with stroke had significantly lower BRS than control subjects (3.3 versus 5.3, P <0.001). Carotid atherosclerosis had no influence on variance of the BRS values in the acute stroke group. Patients with insular involvement had significantly lower BRS than patients with no insular involvement (2.55 versus 4.35, P =0.001) or control subjects (2.55 versus 5.3, P <0.001). Furthermore, patients with left insular involvement had significantly lower BRS than patients with right insular involvement (2.3 versus 3.5, P =0.049). There was no significant difference between patients with no insular lesions and control subjects ( P =0.263).

Conclusions— We demonstrated that baroreflex impairment in acute stroke is not associated with carotid atherosclerosis but with insular involvement. Both insulae seem to participate in processing the baroreceptor information with the left insula being more dominant.

Baroreflex sensitivity in patients with type I diabetes mellitus

OBJECTIVES

To date, the clinical usefulness of measuring baroreflex sensitivity (BRS) to detect impairment of the autonomic nervous system in patients with diabetes mellitus (DM) type I has not been evaluated sufficiently (Mlcáková et al. 2008). The aim of the current study was the determination and statistical comparison of the mean values of BRS in our DM type I patients cohort and in a control group of healthy volunteers as well as the determination of BRS value dependency on the duration of diabetes and the level of glycemic control in DM I patients. We also aimed to determine the inter-individual and intra-individual variability of BRS in our patients.

MATERIAL AND METHODS

We examined 100 patients with type I diabetes mellitus (37 women and 63 men, mean age 30 years, duration of the disease >or= 10 years) and 40 healthy, age- and sex-matched, subjects. Data from the patient cohort were subsequently analysed for duration of the diabetes and the level of glycemic control as assessed by glycated haemoglobin (HbA1c). We used a simple proportional test to compare the occurrence of impaired BRS in the patient cohort and the control group, and a simple linear regression to assess associations between BRS and duration of the diabetes and the levels of glycemic control.

RESULTS

The mean BRS value in our group of diabetic patients and the control group were 10.15 ms/mmHg and 13.35 ms/mmHg, respectively. II. Statistically significant association between BRS impairment and the duration of the disease or level of glycemic control was not confirmed in our patient cohort. III. We observed an increased inter-individual variability and a relatively low intra-individual variability of BRS in patients with DM type I.

CONCLUSIONS

We found a statistically highly significant difference between the proportions of impaired BRS in the group of diabetics vs. control. However, BRS did not correlate with the duration of the disease or with the level of glycemic control significantly. Albeit not reaching statistical significance, trends could be observed, which we consider clinically interesting.