PURPOSE: One of the main challenges in quantitative dynamic contrast-enhanced (DCE) MRI is estimation of the arterial input function (AIF). Usually, the signal from a single artery (ignoring contrast dispersion, partial volume effects and flow artifacts) or a population average of such signals (also ignoring variability between patients) is used. METHODS: Multi-channel blind deconvolution is an alternative approach avoiding most of these problems. The AIF is estimated directly from the measured tracer concentration curves in several tissues. This contribution extends the published methods of multi-channel blind deconvolution by applying a more realistic model of the impulse residue function, the distributed capillary adiabatic tissue homogeneity model (DCATH). In addition, an alternative AIF model is used and several AIF-scaling methods are tested. RESULTS: The proposed method is evaluated on synthetic data with respect to the number of tissue regions and to the signal-to-noise ratio. Evaluation on clinical data (renal cell carcinoma patients before and after the beginning of the treatment) gave consistent results. An initial evaluation on clinical data indicates more reliable and less noise sensitive perfusion parameter estimates. CONCLUSION: Blind multi-channel deconvolution using the DCATH model might be a method of choice for AIF estimation in a clinical setup.

• MeSH
• algoritmy * MeSH
• biologické modely * MeSH
• kapiláry MeSH
• karcinom z renálních buněk krevní zásobení   MeSH
• kontrastní látky MeSH
• ledviny krevní zásobení   MeSH
• lidé MeSH
• magnetická rezonanční tomografie metody   MeSH
• nádory ledvin krevní zásobení   MeSH
• perfuzní zobrazování MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Recent experimental work has revealed unusual features of the effect of certain drugs on cardiac inwardly rectifying potassium currents, including the constitutively active and acetylcholine-induced components of acetylcholine-sensitive current (IKAch). These unusual features have included alternating susceptibility of the current components to activation and inhibition induced by ethanol or nicotine applied at various concentrations, and significant correlation between the drug effect and the current magnitude measured under drug-free conditions. To explain these complex drug effects, we have developed a new type of quantitative model to offer a possible interpretation of the effect of ethanol and nicotine on the IKAch channels. The model is based on a description of IKAch as a sum of particular currents related to the populations of channels formed by identical assemblies of different α-subunits. Assuming two different channel populations in agreement with the two reported functional IKAch-channels (GIRK1/4 and GIRK4), the model was able to simulate all the above-mentioned characteristic features of drug-channel interactions and also the dispersion of the current measured in different cells. The formulation of our model equations allows the model to be incorporated easily into the existing integrative models of electrical activity of cardiac cells involving quantitative description of IKAch. We suppose that the model could also help make sense of certain observations related to the channels that do not show inward rectification. This new ionic channel model, based on a concept we call population type, may allow for the interpretation of complex interactions of drugs with ionic channels of various types, which cannot be done using the ionic channel models available so far.

• MeSH
• acetylcholin farmakologie   MeSH
• biologické modely MeSH
• časové faktory MeSH
• dovnitř usměrňující draslíkové kanály spřažené s G proteiny metabolismus   MeSH
• ethanol farmakologie   MeSH
• gating iontového kanálu účinky léků   MeSH
• nikotin farmakologie   MeSH
• počítačová simulace MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• bulbus olfactorius fyziologie   MeSH
• hipokampus fyziologie   MeSH
• neuronové sítě MeSH
• vápníkové kanály fyziologie   MeSH

Glioma-initiating cells (GIC) are considered the underlying cause of recurrences of aggressive glioblastomas, replenishing the tumor population and undermining the efficacy of conventional chemotherapy. Here we report the discovery that inhibiting T-type voltage-gated Ca(2+) and KCa channels can effectively induce selective cell death of GIC and increase host survival in an orthotopic mouse model of human glioma. At present, the precise cellular pathways affected by the drugs affecting these channels are unknown. However, using cell-based assays and integrated proteomics, phosphoproteomics, and transcriptomics analyses, we identified the downstream signaling events these drugs affect. Changes in plasma membrane depolarization and elevated intracellular Na(+), which compromised Na(+)-dependent nutrient transport, were documented. Deficits in nutrient deficit acted in turn to trigger the unfolded protein response and the amino acid response, leading ultimately to nutrient starvation and GIC cell death. Our results suggest new therapeutic targets to attack aggressive gliomas. Cancer Res; 77(7); 1741-52. ©2017 AACR.

• MeSH
• aminokyseliny metabolismus   MeSH
• biologický transport MeSH
• blokátory kalciových kanálů farmakologie   MeSH
• buněčná smrt MeSH
• dihydropyridiny farmakologie   MeSH
• draslíkové kanály aktivované vápníkem antagonisté a inhibitory   MeSH
• gliom farmakoterapie   metabolismus   patologie   MeSH
• lidé MeSH
• mykotoxiny farmakologie   MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádorové kmenové buňky patologie   MeSH
• nádory mozku farmakoterapie   metabolismus   patologie   MeSH
• proteomika MeSH
• signální dráha UPR účinky léků   MeSH
• sodík metabolismus   MeSH
• vápníkové kanály - typ T fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Clinical trials of nephropathy in people with type 2 diabetes mellitus have not examined the effects of systolic blood pressure (SBP) or pulse pressure (PP) on the time to end-stage renal disease (ESRD) or death. OBJECTIVES: To evaluate the impact of baseline and treated SBP, diastolic blood pressure (DBP), and PP on composite and individual outcomes including doubling of serum creatinine, ESRD, or death in participants of the Reduction of Endpoints in NIDDM (non-insulin-dependent diabetes mellitus) With the Angiotensin II Antagonist Losartan (RENAAL) Study; to assess the specific effect of the angiotensin receptor blocker losartan potassium on composite and renal outcomes; and to explore the implications of dihydropyridine calcium channel blockers as concurrent therapy on composite and renal outcomes. DESIGN: A Cox proportional hazards regression model was used to assess the hazard risk profile of baseline SBP (categories: <130, 130-139, 140-159, 160-179, and > or =180 mm Hg), DBP (categories: <70, 70-79, 80-89, 90-99, and > or =100 mm Hg), and PP (categories: <60, 60-69, 70-79, 80-89, and > or =90 mm Hg) on renal outcomes. PARTICIPANTS: The study comprised 1513 participants with established nephropathy and hypertension associated with type 2 diabetes. INTERVENTIONS: The RENAAL study was a randomized, placebo-controlled study of losartan vs placebo, with other agents added to achieve the goal of a trough BP (ie, BP immediately prior to the next dosing) below 140/90 mm Hg, and had a mean follow-up of 3.4 years. MAIN OUTCOME MEASURES: The primary analysis was time to composite end point of doubling of serum creatinine, ESRD, or death. RESULTS: A baseline SBP range of 140 to 159 mm Hg increased risk for ESRD or death by 38% (P =.05) compared with those below 130 mm Hg. In a multivariate model, every 10-mm Hg rise in baseline SBP increased the risk for ESRD or death by 6.7% (P =.007); the same rise in DBP decreased the risk by 10.9% (P =.01) when adjusting for urinary albumin-creatinine ratio, serum creatinine, serum albumin, hemoglobin, and hemoglobin A1c. Those randomized to the losartan group with a baseline PP above 90 mm Hg had a 53.5% risk reduction for ESRD alone (P =.003) and a 35.5% risk reduction for ESRD or death (P =.02) compared with the placebo group. CONCLUSIONS: Baseline SBP is a stronger predictor than DBP of renal outcomes in those with nephropathy resulting from type 2 diabetes. Those with the highest baseline PP have the highest risk for nephropathy progression but also garner the greatest risk reduction with SBP lowered to less than 140 mm Hg.

• MeSH
• antihypertenziva terapeutické užití   MeSH
• blokátory kalciových kanálů terapeutické užití   MeSH
• chronické selhání ledvin prevence a kontrola   MeSH
• diabetes mellitus 2. typu farmakoterapie   patofyziologie   MeSH
• diabetické nefropatie farmakoterapie   patofyziologie   MeSH
• dvojitá slepá metoda MeSH
• hypertenze farmakoterapie   patofyziologie   MeSH
• klinické zkoušky jako téma MeSH
• lidé středního věku MeSH
• lidé MeSH
• losartan terapeutické užití   MeSH
• progrese nemoci MeSH
• proporcionální rizikové modely MeSH
• randomizované kontrolované studie jako téma MeSH
• rizikové faktory MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• multicentrická studie MeSH

Inward rectifier potassium currents (I Kir,x) belong to prominent ionic currents affecting both resting membrane voltage and action potential repolarization in cardiomyocytes. In existing integrative models of electrical activity of cardiac cells, they have been described as single current components. The proposed quantitative model complies with findings indicating that these channels are formed by various homomeric or heteromeric assemblies of channel subunits with specific functional properties. Each I Kir,x may be expressed as a total of independent currents via individual populations of identical channels, i.e., channels formed by the same combination of their subunits. Solution of the model equations simulated well recently observed unique manifestations of dual ethanol effect in rat ventricular and atrial cells. The model reflects reported occurrence of at least two binding sites for ethanol within I Kir,x channels related to slow allosteric conformation changes governing channel conductance and inducing current activation or inhibition. Our new model may considerably improve the existing models of cardiac cells by including the model equations proposed here in the particular case of the voltage-independent drug-channel interaction. Such improved integrative models may provide more precise and, thus, more physiologically relevant results.

• MeSH
• akční potenciály * MeSH
• alosterická regulace MeSH
• draslíkové kanály dovnitř usměrňující chemie   metabolismus   MeSH
• ethanol farmakologie   MeSH
• kardiomyocyty účinky léků   metabolismus   fyziologie   MeSH
• krysa rodu rattus MeSH
• modely kardiovaskulární MeSH
• multimerizace proteinu MeSH
• srdce - funkce komor MeSH
• srdeční komory cytologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Bronchodilator aminophylline may induce atrial or less often ventricular arrhythmias. The mechanism of this proarrhythmic side effect has not been fully explained. Modifications of inward rectifier potassium (Kir) currents including IK1 are known to play an important role in arrhythmogenesis; however, no data on the aminophylline effect on these currents have been published. Hence, we tested the effect of aminophylline (3-100 μM) on IK1 in enzymatically isolated rat ventricular myocytes using the whole-cell patch-clamp technique. A dual steady-state effect of aminophylline was observed; either inhibition or activation was apparent in individual cells during the application of aminophylline at a given concentration. The smaller the magnitude of the control IK1, the more likely the activation of the current by aminophylline and vice versa. The effect was reversible; the relative changes at -50 and -110 mV did not differ. Using IK1 channel population model, the dual effect was explained by the interaction of aminophylline with two different channel populations, the first one being inhibited and the second one being activated. Considering various fractions of these two channel populations in individual cells, varying effects observed in the measured cells could be simulated. We propose that the dual aminophylline effect may be related to the direct and indirect effect of the drug on various Kir2.x subunits forming the homo- and heterotetrameric IK1 channels in a single cell. The observed IK1 changes induced by clinically relevant concentrations of aminophylline might contribute to arrhythmogenesis related to the use of this bronchodilator in clinical medicine.

• MeSH
• aminofylin škodlivé účinky   MeSH
• bronchodilatancia škodlivé účinky   MeSH
• draslík farmakologie   MeSH
• draslíkové kanály dovnitř usměrňující * MeSH
• kardiomyocyty fyziologie   MeSH
• krysa rodu rattus MeSH
• srdeční arytmie MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Specialized clinical care for cystic fibrosis (CF) in Cyprus, a small island country, has been implemented since the 1990s. However, only recently, a national CF patient registry has been established for the systematic recording of patients' data. In this study, we aim to present data on the epidemiological, genotypic and phenotypic features of CF patients in the country from the most recent data collection in 2019, with particular emphasis on notable rare or unique cases. RESULTS: Overall, data from 52 patients are presented, 5 of whom have deceased and 13 have been lost to follow-up in previous years. The mean age at diagnosis was 7.2 ± 12.3 years, and the mean age of 34 alive patients by the end of 2019 was 22.6 ± 13.2 years. Patients most commonly presented at diagnosis with acute or persistent respiratory symptoms (46.2%), failure to thrive or malnutrition (40.4%), and dehydration or electrolyte imbalance (32.7%). Sweat chloride levels were diagnostic (above 60 mmol/L) in 81.8% of examined patients. The most common identified mutation was p.Phe508del (F508del) (45.2%), followed by p.Leu346Pro (L346P) (6.7%), a mutation detected solely in individuals of Cypriot descent. The mean BMI and FEV1 z-scores were 0.2 ± 1.3 and - 2.1 ± 1.7 across all age groups, respectively, whereas chronic Pseudomonas aeruginosa colonization was noted in 26.9% of patients. The majority of patients (74.5%) were eligible to receive at least one of the available CFTR modulator therapies. In 25% of patients we recovered rare or unique genotypic profiles, including the endemic p.Leu346Pro (L346P), the rare CFTR-dup2, the co-segregated c.4200_4201delTG/c.489 + 3A > G, and the polymorphism p.Ser877Ala. CONCLUSIONS: CF patient registries are particularly important in small or isolated populations, such as in Cyprus, with rare or unique disease cases. Their operation is necessary for the optimization of clinical care provided to CF patients, enabling their majority to benefit from evolving advances in precision medicine.

• MeSH
• cystická fibróza * genetika   MeSH
• demografie MeSH
• dítě MeSH
• dospělí MeSH
• laboratoře MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mutace genetika   MeSH
• protein CFTR * genetika   MeSH
• registrace MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Úvod/cieľ: Asociácia génov CDKAL1 a KCNQ1 s diabetes mellitus 2. typu (DM2T) bola potvrdená viacerými celogénomovými asociačnými štúdiami v kaukazskej aj ázijskej populácii. U oboch génov sa predpokladá vplyv na riziko rozvoja DM2T prostredníctvom poruchy inzulínovej sekrécie. Vychádzali sme z predpokladu, že prítomnosť rizikovej alely môže predisponovať k skoršiemu nástupu DM2T. Cieľom našej štúdie bolo zistiť frekvenciu rizikových alel polymorfizmov rs7756992 génu CDKAL1 a rs163184 génu KCNQ1 a analyzovať ich vzťah k veku stanovenia diagnózy DM2T v populácii Slovenska. Metódy: V súbore 538 pacientov s DM2T boli určené genotypy polymorfizmu rs7756992 A/G génu CDKAL1 a polymorfizmu rs163184 G/T génu KCNQ1 metódou asymetrickej PCR s následnou analýzou krivky topenia. Antropometrické a laboratórne parametre boli vyšetrené štandardnými metódami. Vzhľadom na analýzu 2 génov bola definovaná požadovaná hladina štatistickej významnosti na hladine p < 0,025. Výsledky: Rizikoví homozygoti (GG) polymorfizmu KCNQ1 mali v recesívnom modeli o 2 roky vyšší priemerný vek diagnózy DM2T ako nosiči alely T (GT + TT), ale hodnota štatistickej významnosti nedosiahla preddefinovanú úroveň. Pri polymorfizme génu CDKAL1 nebol pozorovaný signifikantný rozdiel vo veku diagnózy DM2T medzi jednotlivými genotypmi. Záver: V tejto štúdii sme nezistili vzťah medzi sledovanými polymorfizmami génov CDKAL1 a KCNQ1 a skorším vekom nástupu DM2T v populácii Slovenska.

Background/aims: The association of CDKAL1 and KCNQ1 genes with type 2 diabetes mellitus (DM2T) was confirmed by several genome-wide association studies in both Caucasian and Asian populations. For both genes, it is supposed that the risk of DM2T development is related to impaired insulin secretion. Based on assumption that the presence of risk allele might predispose to an earlier onset of DM2T, the aim of the present study was to assess the frequency of risk alleles of CDKAL1 rs7756992 and KCNQ1 rs163184 poly­morphisms and to analyze their association with the age at DM2T diagnosis in the Slovakian population. Methods: CDKAL1 rs7756992 A/G and KCNQ1 rs163184 G/T polymorphisms were genotyped using asymmetric PCR with subsequent melting curve analysis in a group of 538 patients with DM2T. Anthropometric and laboratory parameters were determined by using standard methods. Since two genes were analysed, the required level for statistical significance was defined as p < 0.025. Results: Risk homozygotes (GG) for KCNQ1 polymorphism had higher mean age of DM2T diagnosis by 2 years when compared to T-allele carriers (GT + TT) in a recessive model, but the difference did not reach the predefined level of statistical significance. No relationship of CDKAL1 polymorphism to the age at onset of DM2T diagnosis was observed. Conclusions: In the present study, no relationship of CDKAL1 and KCNQ1 polymorphisms to the earlier onset of type 2 diabetes was observed.

• MeSH
• celogenomová asociační studie MeSH
• cyklin-dependentní kinasa 5 genetika   MeSH
• diabetes mellitus 2. typu diagnóza   genetika   MeSH
• draslíkový kanál KCNQ1 genetika   MeSH
• genotyp MeSH
• lidé středního věku MeSH
• lidé MeSH
• polymorfismus genetický MeSH
• senioři MeSH
• věk při počátku nemoci MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Geografické názvy
• Slovenská republika MeSH

BACKGROUND AND OBJECTIVES: The relationship between serum potassium (S(K)) and mortality in chronic kidney disease (CKD) has not been systematically investigated. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We examined the predictors and mortality association of S(K) in the Renal Research Institute CKD Study cohort, wherein 820 patients with CKD were prospectively followed at four US centers for an average of 2.6 years. Predictors of S(K) were investigated using linear and repeated measures regression models. Associations between S(K) and mortality, the outcomes of ESRD, and cardiovascular events in time-dependent Cox models were examined. RESULTS: The mean age was 60.5 years, 80% were white, 90% had hypertension, 36% had diabetes, the average estimated GFR was 25.4 ml/min per 1.73 m(2), and mean baseline S(K) was 4.6 mmol/L. Higher S(K) was associated with male gender, lower estimated GFR and serum bicarbonate, absence of diuretic and calcium channel blocker use, diabetes, and use of angiotensin-converting enzyme inhibitors and/or statins. A U-shaped relationship between S(K) and mortality was observed, with mortality risk significantly greater at S(K) < or = 4.0 mmol/L compared with 4.0 to 5.5 mmol/L. Risk for ESRD was elevated at S(K) < or = 4 mmol/L in S(K) categorical models. Only the composite of cardiovascular events or death as an outcome was associated with higher S(K) (> or = 5.5). CONCLUSIONS: Although clinical practice usually emphasizes greater attention to elevated S(K) in the setting of CKD, our results suggest that patients who have CKD and low or even low-normal S(K) are at higher risk for dying than those with mild to moderate hyperkalemia.

• MeSH
• biologické markery krev   MeSH
• časové faktory MeSH
• chronické selhání ledvin komplikace   krev   mortalita   MeSH
• draslík krev   MeSH
• financování organizované MeSH
• hodnocení rizik MeSH
• hyperkalemie komplikace   krev   mortalita   MeSH
• hypokalemie komplikace   krev   mortalita   MeSH
• kardiovaskulární nemoci etiologie   krev   mortalita   MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• lineární modely MeSH
• prognóza MeSH
• proporcionální rizikové modely MeSH
• prospektivní studie MeSH
• rizikové faktory MeSH
• senioři MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• multicentrická studie MeSH
• Geografické názvy
• Spojené státy americké MeSH