Impact of Angiotensin-converting Enzyme and Matrix Metalloproteinase-3 Gene Polymorphisms on Risk for Developing Vascular Access Failure in Hemodialysis Patients - A Pilot Study.

For adequate hemodialysis, functional vascular access is obligatory. Neointimal hyperplasia (NIH) has a central role in stenosis and thrombosis development, which represent the most frequent causes of vascular access failure. Polymorphism of different genes that have a significant role in endothelial function may have an impact on NIH development. Therefore, the aim of our study is to determine the effect of angiotensin-converting enzyme (ACE) I/D and matrix metalloproteinase-3 (MMP3) 5A/6A polymorphism on risk for developing vascular access failure in hemodialysis patients. The study included 200 patients on regular hemodialysis at Nephrology Department, University Medical Center Zvezdara. Retrospective analysis included a collection of general and vascular access data from medical records. Genetic analysis was performed by using polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP). Patients were divided into two groups: Group 1-patients who have never experienced vascular access failure and Group 2-patients who have at least one spontaneous vascular access failure. There was no difference in age, gender, hemodialysis vintage, main diagnosis, presence of hypertension, and diabetes mellitus between the two groups. There were no statistically significant differences in the frequencies of ACE and MMP3 genotypes between the two groups. Without statistical significance, it was found that homozygotes for I allele had two times higher risk for developing vascular access failure than homozygotes for D allele (OR 2.00; 95%CI: 0.727-5.503; P = 0.180). In addition, patients with 5A allele have 1.7 times higher risk for developing vascular access failure compared with patients without this allele (OR 1.745; 95% CI: 0.868-3.507; P = 0.118). Patients with vascular access failure do not have different genotype distribution regarding ACE gene and MMP3 gene polymorphism as compared with patients without vascular access failure. Still, homozygotes for I allele and homozygotes for 5A allele have higher risk for developing vascular access failure compared with other patients.

The 5A Allele of the MMP3-Gene Promoter Polymorphism Is a Risk Factor for Poor Outcome of Hemodialysis Patients.

Cardiovascular morbidity is the leading cause of death in dialysis patients and many risk factors have been involved in its pathogenesis. Genetic susceptibility may be of importance including polymorphism for matrix metalloproteinase 3 (MMP3), which is an enzyme that catalyzes the degradation of collagen, proteoglycans, fibronectin, laminine and elastin. The MMP3 gene promoter contains an insertion/deletion polymorphism characterised by an array of 5 or 6 adenosine residues (5A/6A) at -1612 position. Literature data show that the 5A or 6A allele of the MMP3 gene shows different risk for cardiovascular and overall outcome in general population. The aim was to analyze the -1612 5A/6A promoter polymorphism in a group of hemodialysis patients and to correlate the findings with cardiovascular morbidity and 7-year all-cause and cardiovascular mortality. This study included 196 patients on hemodialysis for longer than six months at University Medical Center Zvezdara. The leading causes of end stage renal disease were hypertension and diabetes mellitus. Venous blood was collected on midweek dialysis session and genotype analysis was performed by using polymerase chain reaction-restriction fragment length polymorphism method. Among the 198 hemodialysis patients, there were 142 (72%) 5A/6A heterozygotes, 12 (6%) 5A/5A homozygotes, and 44 (22%) 6A/6A homozygotes. These data are consistent with Hardy-Weinberg equilibrium. After 7-year follow-up, the 5A homozygotes showed the lowest all-cause and cardiovascular survival, while the 6A homozygotes showed the highest cardiovascular survival. The 5A allele of the MMP3-gene promoter polymorphism is a potential risk factor in the poor outcome of hemodialysis patients.

¼Treatment Resistance« Enigma Resolved by Pharmacogenomics - A Case Study of Clozapine Therapy in Schizophrenia.

The introduction of antipsychotic medication in the 1950s forever changed the outlook on the treatment of schizophrenia, although there is still a large proportion of patients who do not reach functional recovery. At least 30% of patients do not respond to clozapine, the tricyclic dibenzodiazepine with complex pharmacological actions, which was proven to be more effective than any other antipsychotic in the treatment of schizophrenia. According to most of the therapeutic guidelines for schizophrenia, clozapine is the third line therapy for patients who did not respond to other antipsychotics. Large inter-individual variability exists for clozapine bioavailability and plasma steady-state concentrations and clearance. Clozapine is metabolized by the cytochrome P450 oxidase enzyme family (CYP450). Cytochrome P450 1A2 (CYP1A2), which is polymorphically expressed in humans, is the main enzyme of clozapine metabolism. This case report addresses the influence of CYP1A2*1F genetic polymorphism on clozapine metabolism, explains the primary non-response of a young patient with schizophrenia due to increased gene expression in homozygous genotype *1F/*1F (increased metabolism of clozapine) and underlies the importance of personalizing schizophrenia treatment by means of genetic and other molecular tools, at least in the cases of ¼treatment resistance«.

Upregulation of nucleoside triphosphate diphosphohydrolase-1 and ecto-5'-nucleotidase in rat hippocampus after repeated low-dose dexamethasone administration.

Although dexamethasone (DEX), a synthetic glucocorticoid receptor (GR) analog with profound effects on energy metabolism, immune system, and hypothalamic-pituitary-adrenal axis, is widely used therapeutically, its impact on the brain is poorly understood. The aim of the present study was to explore the effect of repeated low-dose DEX administration on the activity and expression of the ectonucleotidase enzymes which hydrolyze and therefore control extracellular ATP and adenosine concentrations in the synaptic cleft. Ectonucleotidases tested were ectonucleoside triphosphate diphosphohydrolase 1-3 (NTPDase1-3) and ecto-5'-nucleotidase (eN), whereas the effects were evaluated in two brain areas that show different sensitivity to glucocorticoid action, hippocampus, and cerebral cortex. In the hippocampus, but not in cerebral cortex, modest level of neurodegenerative changes as well as increase in ATP, ADP, and AMP hydrolysis and upregulation of NTPDase1 and eN mRNA expression ensued under the influence of DEX. The observed pattern of ectonucleotidase activation, which creates tissue volume with enhanced capacity for adenosine formation, is the hallmark of the response after different insults to the brain.

Polymorphism of angiotensin converting enzyme in hemodialysis patients--association with cardiovascular morbidity.

INTRODUCTION: Cardiovascular morbidity and mortality are the major concern in dialysis patients and many risk factors are thought to be involved in its pathogenesis. Apart from traditional and non-traditional risk factors, the genetic susceptibility may be of importance, including renin-angiotensin system gene polymorphism. The aim of this study was to analyse renin-angiotensin system polymorphism in our group of hemodialysis patients and to correlate the findings with cardiovascular morbidity. MATERIAL AND METHODS: The study included 196 patients on regular hemodialysis on polysulphone membrane three times per week for more than six months. Genetic analysis was performed by using polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: Out of 196 patients, 55% had I/D genotype, 35% had D/D and 10% had I/I, including angiotensin-converting enzyme polymorphism. It was shown that the patients with D allele genotype developed a significantly higher incidence of left ventricular hypertrophy and peripheral vascular disease. The angiotensin-converting enzyme polymorphism showed a significant association with the incidence of cerebrovascular accident and hyperlipoproteinemia in our group of hemodialysis patients. CONCLUSION: The angiotensin-converting enzyme gene polymorphism is associated with the development of cerebrovascular accidents and hyperlipoproteinemia. Allele D of this gene increases the risk for the development of left ventricular hypertrophy and peripheral vascular disease significantly in hemodialysis patients. A longer follow-up is needed to make the definitive conclusion about the influence of angiotensin-converting enzyme polymorphism on cardiovascular morbidity and its importance in everyday clinical practice.

Low-frequency repetitive transcranial magnetic stimulation in the right prefrontal cortex combined with partial sleep deprivation in treatment-resistant depression: a randomized sham-controlled trial.

INTRODUCTION: Sham-controlled low-frequency repetitive transcranial magnetic stimulation (rTMS) was used in patients with pharmacoresistant major depression as an added treatment along with partial sleep deprivation (PSD). In addition, the potential predictive role of brain-derived neurotrophic factor genetic polymorphism on treatment response was analyzed. METHODS: We recruited 19 female patients (48.3 ± 8.6 years old) with treatment-resistant unipolar major depression (Hamilton Depression Rating Scale [HDRS] score ≥20) who were on a stable antidepressant treatment. They received either 1-Hz rTMS or sham stimulation over the right dorsolateral prefrontal cortex (intensity of 110% of the threshold; 3000 stimuli per protocol; and 10 daily sessions). Additionally, PSD was applied once per week during the treatment. The patients were evaluated (HDRS and Clinical Global Impression Scale) by a blind rater at baseline (B) and after 2 and 3 weeks (W2 and W3) of treatment for short-term outcome. Long-term evaluations were performed after 12 (W12) and 24 weeks (W24) for patients who received active stimulation. RESULTS: Eleven patients in the active group showed a significant HDRS score reduction from 30.09 ± 3.53 (B) to 16.73 ± 5.71 (W3) compared to the lack of therapeutic response in the sham-treated patients. The long-term follow-up for the active group included 64% of the responders at W12 and 55% at W24. Full remission (HDRS ≤10) was achieved in 5 of 11 patients. Four of these 5 patients with long-term sustained remission expressed the Val66Val genotype. CONCLUSION: Our study suggests a clinically relevant response, persisting for up to 6 months, from 1-Hz rTMS over the right dorsolateral prefrontal cortex and PSD in patients with pharmacoresistant major depression. The brain-derived neurotrophic factor Val66Val homozygous genotype may be related to a better treatment outcome.