Acute reversal of phospholamban inhibition facilitates the rhythmic whole-cell propagating calcium waves in isolated ventricular myocytes

Phospholamban (PLB) inhibits the activity of cardiac sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a). Phosphorylation of PLB during sympathetic activation reverses SERCA2a inhibition, increasing SR Ca(2+) uptake. However, sympathetic activation also modulates multiple other intracellular targets in ventricular myocytes (VMs), making it impossible to determine the specific effects of the reversal of PLB inhibition on the spontaneous SR Ca(2+) release. Therefore, it remains unclear how PLB regulates rhythmic activity in VMs. Here, we used the Fab fragment of 2D12, a monoclonal anti-PLB antibody, to test how acute reversal of PLB inhibition affects the spontaneous SR Ca(2+) release in normal VMs. Ca(2+) sparks and spontaneous Ca(2+) waves (SCWs) were recorded in the line-scan mode of confocal microscopy using the Ca(2+) fluorescent dye Fluo-4 in isolated permeabilized mouse VMs. Fab, which reverses PLB inhibition, significantly increased the frequency, amplitude, and spatial/temporal spread of Ca(2+) sparks in VMs exposed to 50 nM free [Ca(2+)]. At physiological diastolic free [Ca(2+)] (100-200 nM), Fab facilitated the formation of whole-cell propagating SCWs. At higher free [Ca(2+)], Fab increased the frequency and velocity, but decreased the decay time of the SCWs. cAMP had little additional effect on the frequency or morphology of Ca(2+) sparks or SCWs after Fab addition. These findings were complemented by computer simulations. In conclusion, acute reversal of PLB inhibition alone significantly increased the spontaneous SR Ca(2+) release, leading to the facilitation and organization of whole-cell propagating SCWs in normal VMs. PLB thus plays a key role in subcellular Ca(2+) dynamics and rhythmic activity of VMs.

Genetic diversity and relationships in cultivars of Lolium multiflorum Lam. using sequence-related amplified polymorphism markers

Sequence-related amplified polymorphism (SRAP) markers were used to analyze and estimate the genetic variability, level of diversity, and relationships among 20 cultivars and strains of annual ryegrass (Lolium multiflorum Lam.). Eighteen SRAP primer combinations generated 334 amplification bands, of which 298 were polymorphic. The polymorphism information content ranged from 0.4715 (me10 + em1) to 0.5000 (me5 + em7), with an average of 0.4921. The genetic similarity coefficient ranged from 0.4304 to 0.8529, and coefficients between 0.65 and 0.90 accounted for 90.00%. The cluster analysis separated the accessions into five groups partly according to their germplasm resource origins.

Association of DNA repair gene polymorphisms with response to chemotherapy and prognosis of gastric cancer

We investigated the correlation between the response to chemotherapy in patients and excision repair cross-complimenta-ry group 1 gene (ERCC1) and xeroderma pigmentosum complemen-tation group F gene (XPF) polymorphisms and the effect of these polymorphisms on the clinical outcome of gastric cancer. Samples from a total of 255 patients with newly diagnosed and histopatho-logically confirmed primary gastric cancer were collected in our study. The ERCC1 rs11615, ERCC1 rs2298881, XPF rs2276465, and XPF rs6498486 polymorphisms were genotyped. Among the 255 patients, the median follow-up time was 29.7 months. A total of 103 patients (40.4%) died from gastric cancer during the follow-up period. We observed that the XPF rs6498486 CC genotype and the XPF rs2276465 GG genotype were associated with response to che-motherapy, with odds ratios and 95% confidence intervals of 3.88 (1.23-16.07) and 2.66 (1.17-6.45), respectively. In the Cox propor-tional hazards model, patients carrying the ERCC1 rs11615 AA gen-otype and the XPF rs2276465 GG genotype showed only a 0.22- and 0.30-fold increased risk of death from gastric cancer. We found that the XPF rs6498486 and XPF rs2276465 polymorphisms are mark-ers of response to oxaliplatin/5-fluorouracil-based chemotherapy in gastric cancer patients.

Low band-gap conjugated polymers with strong interchain aggregation and very high hole mobility towards highly efficient thick-film polymer solar cells

Absorption spectra of polymer FBT-Th4 (1,4) (M n = 46.4 Kg/mol, E g = 1.62 eV, and HOMO = -5.36 eV) indicate strong interchain aggregation ability. High hole mobilities up to 1.92 cm(2) (V s)(-1) are demonstrated in OFETs fabricated under mild conditions. Inverted solar cells with active layer thicknesses ranging from 100 to 440 nm display PCEs exceeding 6.5%, with the highest efficiency of 7.64% achieved with a 230 nm thick active layer.

The structural basis for phospholamban inhibition of the calcium pump in sarcoplasmic reticulum

P-type ATPases are a large family of enzymes that actively transport ions across biological membranes by interconverting between high (E1) and low (E2) ion-affinity states; these transmembrane transporters carry out critical processes in nearly all forms of life. In striated muscle, the archetype P-type ATPase, SERCA (sarco(endo)plasmic reticulum Ca(2+)-ATPase), pumps contractile-dependent Ca(2+) ions into the lumen of sarcoplasmic reticulum, which initiates myocyte relaxation and refills the sarcoplasmic reticulum in preparation for the next contraction. In cardiac muscle, SERCA is regulated by phospholamban (PLB), a small inhibitory phosphoprotein that decreases the Ca(2+) affinity of SERCA and attenuates contractile strength. cAMP-dependent phosphorylation of PLB reverses Ca(2+)-ATPase inhibition with powerful contractile effects. Here we present the long sought crystal structure of the PLB-SERCA complex at 2.8-Å resolution. The structure was solved in the absence of Ca(2+) in a novel detergent system employing alkyl mannosides. The structure shows PLB bound to a previously undescribed conformation of SERCA in which the Ca(2+) binding sites are collapsed and devoid of divalent cations (E2-PLB). This new structure represents one of the key unsolved conformational states of SERCA and provides a structural explanation for how dephosphorylated PLB decreases Ca(2+) affinity and depresses cardiac contractility.

Amiodarone inhibits apamin-sensitive potassium currents

BACKGROUND

Apamin sensitive potassium current (I KAS), carried by the type 2 small conductance Ca(2+)-activated potassium (SK2) channels, plays an important role in post-shock action potential duration (APD) shortening and recurrent spontaneous ventricular fibrillation (VF) in failing ventricles.

OBJECTIVE

To test the hypothesis that amiodarone inhibits I KAS in human embryonic kidney 293 (HEK-293) cells.

METHODS

We used the patch-clamp technique to study I KAS in HEK-293 cells transiently expressing human SK2 before and after amiodarone administration.

RESULTS

Amiodarone inhibited IKAS in a dose-dependent manner (IC50, 2.67 ± 0.25 µM with 1 µM intrapipette Ca(2+)). Maximal inhibition was observed with 50 µM amiodarone which inhibited 85.6 ± 3.1% of IKAS induced with 1 µM intrapipette Ca(2+) (n = 3). IKAS inhibition by amiodarone was not voltage-dependent, but was Ca(2+)-dependent: 30 µM amiodarone inhibited 81.5±1.9% of I KAS induced with 1 µM Ca(2+) (n = 4), and 16.4±4.9% with 250 nM Ca(2+) (n = 5). Desethylamiodarone, a major metabolite of amiodarone, also exerts voltage-independent but Ca(2+) dependent inhibition of I KAS.

CONCLUSION

Both amiodarone and desethylamiodarone inhibit I KAS at therapeutic concentrations. The inhibition is independent of time and voltage, but is dependent on the intracellular Ca(2+) concentration. SK2 current inhibition may in part underlie amiodarone's effects in preventing electrical storm in failing ventricles.

Apamin-sensitive calcium-activated potassium currents in rabbit ventricles with chronic myocardial infarction

INTRODUCTION

The apamin-sensitive small-conductance calcium-activated potassium current (IKAS ) is increased in heart failure. It is unknown if myocardial infarction (MI) is also associated with an increase of IKAS .

METHODS AND RESULTS

We performed Langendorff perfusion and optical mapping in 6 normal hearts and 10 hearts with chronic (5 weeks) MI. An additional 6 normal and 10 MI hearts were used for patch clamp studies. The infarct size was 25% (95% confidence interval, 20-31) and the left ventricular ejection fraction was 50 (46-54). The rabbits did not have symptoms of heart failure. The action potential duration measured to 80% repolarization (APD80 ) in the peri-infarct zone (PZ) was 150 (142-159) milliseconds, significantly (P = 0.01) shorter than that in the normal ventricles (167 [158-177] milliseconds. The intracellular Ca transient duration was also shorter in the PZ (148 [139-157] milliseconds) than that in normal ventricles (168 [157-180] milliseconds; P = 0.017). Apamin prolonged the APD80 in PZ by 9.8 (5.5-14.1)%, which is greater than that in normal ventricles (2.8 [1.3-4.3]%, P = 0.006). Significant shortening of APD80 was observed at the cessation of rapid pacing in MI but not in normal ventricles. Apamin prevented postpacing APD80 shortening. Patch clamp studies showed that IKAS was significantly higher in the PZ cells (2.51 [1.55-3.47] pA/pF, N = 17) than in the normal cells (1.08 [0.36-1.80] pA/pF, N = 15, P = 0.019).

CONCLUSION

We conclude that IKAS is increased in MI ventricles and contributes significantly to ventricular repolarization especially during tachycardia.

Apamin-sensitive potassium current modulates action potential duration restitution and arrhythmogenesis of failing rabbit ventricles

BACKGROUND

Apamin-sensitive K currents (I(KAS)) are upregulated in heart failure. We hypothesize that apamin can flatten action potential duration restitution (APDR) curve and can reduce ventricular fibrillation duration in failing ventricles.

METHODS AND RESULTS

We simultaneously mapped membrane potential and intracellular Ca (Ca(i)) in 7 rabbit hearts with pacing-induced heart failure and in 7 normal hearts. A dynamic pacing protocol was used to determine APDR at baseline and after apamin (100 nmol/L) infusion. Apamin did not change APD(80) in normal ventricles, but prolonged APD(80) in failing ventricles at either long (≥300 ms) or short (≤170 ms) pacing cycle length, but not at intermediate pacing cycle length. The maximal slope of APDR curve was 2.03 (95% confidence interval, 1.73-2.32) in failing ventricles and 1.26 (95% confidence interval, 1.13-1.40) in normal ventricles at baseline (P=0.002). After apamin administration, the maximal slope of APDR in failing ventricles decreased to 1.43 (95% confidence interval, 1.01-1.84; P=0.018), whereas no significant changes were observed in normal ventricles. During ventricular fibrillation in failing ventricles, the number of phase singularities (baseline versus apamin, 4.0 versus 2.5), dominant frequency (13.0 versus 10.0 Hz), and ventricular fibrillation duration (160 versus 80 s) were all significantly (P<0.05) decreased by apamin.

CONCLUSIONS

Apamin prolongs APD at long and short, but not at intermediate pacing cycle length in failing ventricles. I(KAS) upregulation may be antiarrhythmic by preserving the repolarization reserve at slow heart rate, but is proarrhythmic by steepening the slope of APDR curve, which promotes the generation and maintenance of ventricular fibrillation.

Low-level vagus nerve stimulation upregulates small conductance calcium-activated potassium channels in the stellate ganglion

BACKGROUND

Small conductance calcium-activated potassium (SK) channels are responsible for afterhyperpolarization that suppresses nerve discharges.

OBJECTIVES

To test the hypothesis that low-level vagus nerve stimulation (LL-VNS) leads to the upregulation of SK2 proteins in the left stellate ganglion.

METHODS

Six dogs (group 1) underwent 1-week LL-VNS of the left cervical vagus nerve. Five normal dogs (group 2) were used as controls. SK2 protein levels were examined by using Western blotting. The ratio between SK2 and glyceraldehydes-3-phosphate-dehydrogenase levels was used as an arbitrary unit (AU).

RESULTS

We found higher SK2 expression in group 1 (0.124 ± 0.049 AU) than in group 2 (0.085 ± 0.031 AU; P<.05). Immunostaining showed that the density of nerve structures stained with SK2 antibody was also higher in group 1 (11,546 ± 7,271 μm(2)/mm(2)) than in group 2 (5321 ± 3164 μm(2)/mm(2); P<.05). There were significantly more ganglion cells without immunoreactivity to tyrosine hydroxylase (TH) in group 1 (11.4%±2.3%) than in group 2 (4.9% ± 0.7%; P<.05). The TH-negative ganglion cells mostly stained positive for choline acetyltransferase (95.9% ± 2.8% in group 1 and 86.1% ± 4.4% in group 2; P = .10). Immunofluorescence confocal microscopy revealed a significant decrease in the SK2 staining in the cytosol but an increase in the SK2 staining on the membrane of the ganglion cells in group 1 compared to group 2.

CONCLUSIONS

Left LL-VNS results in the upregulation of SK2 proteins, increased SK2 protein expression in the cell membrane, and increased TH-negative (mostly choline acetyltransferase-positive) ganglion cells in the left stellate ganglion. These changes may underlie the antiarrhythmic efficacy of LL-VNS in ambulatory dogs.

Heterogeneous upregulation of apamin-sensitive potassium currents in failing human ventricles

Background

We previously reported that I_KAS are heterogeneously upregulated in failing rabbit ventricles and play an important role in arrhythmogenesis. This study goal is to test the hypothesis that subtype 2 of the small‐conductance Ca²⁺ activated K⁺ (SK2) channel and apamin‐sensitive K⁺ currents (I_KAS) are upregulated in failing human ventricles.

Methods and Results

We studied 12 native hearts from transplant recipients (heart failure [HF] group) and 11 ventricular core biopsies from patients with aortic stenosis and normal systolic function (non‐HF group). I_KAS and action potential were recorded with patch‐clamp techniques, and SK2 protein expression was studied by Western blotting. When measured at 1 μmol/L Ca²⁺ concentration, I_KAS was 4.22 (median) (25th and 75th percentiles, 2.86 and 6.96) pA/pF for the HF group (n=11) and 0.98 (0.54 and 1.72) pA/pF for the non‐HF group (n=8, P=0.008). I_KAS was lower in the midmyocardial cells than in the epicardial and the endocardial cells. The Ca²⁺ dependency of I_KAS in HF myocytes was shifted leftward compared to non‐HF myocytes (K_d 314 versus 605 nmol/L). Apamin (100 nmol/L) increased the action potential durations by 1.77% (−0.9% and 7.3%) in non‐HF myocytes and by 11.8% (5.7% and 13.9%) in HF myocytes (P=0.02). SK2 protein expression was 3‐fold higher in HF than in non‐HF.

Conclusions

There is heterogeneous upregulation of I_KAS densities in failing human ventricles. The midmyocardial layer shows lower I_KAS densities than epicardial and endocardial layers of cells. Increase in both Ca²⁺ sensitivity and SK2 protein expression contributes to the I_KAS upregulation.

Imaging arrhythmogenic calcium signaling in intact hearts

Protein complex of the cardiac junctional sarcoplasmic reticulum (SR) membrane formed by type 2 ryanodine receptor, junction, triadin, and calsequestrin is responsible for controlling SR calcium (Ca) release. Increased intracellular calcium (Ca(i)) activates the electrogenic sodium-Ca exchanger current, which is known to be important in afterdepolarization and triggered activities (TAs). Using optical-mapping techniques, it is possible to simultaneously map membrane potential (V (m)) and Ca(i) transient in Langendorff-perfused rabbit ventricles to better define the mechanisms by which V (m) and Ca(i) interactions cause early afterdepolarizations (EADs). Phase 3 EAD is dependent on heterogeneously prolonged action potential duration (APD). Electrotonic currents that flow between a persistently depolarized region and its recovered neighbors underlies the mechanisms of phase 3 EADs and TAs. In contrast, "late phase-3 EAD" is induced by APD shortening, not APD prolongation. In failing ventricles, upregulation of apamin-sensitive Ca-activated potassium (K) channels (I(KAS)) causes APD shortening after fibrillation-defibrillation episodes. Shortened APD in the presence of large Ca(i) transients generates late-phase 3 EADs and recurrent spontaneous ventricular fibrillation. The latter findings suggest that I (KAS) may be a novel antiarrhythmic targets in patients with heart failure and electrical storms.

Construction and evaluation of high-quality n-ZnO nanorod/p-diamond heterojunctions

Vertically-aligned ZnO nanorods (NRs) arrays were synthesized by a low-temperature solution method on boron-doped diamond (BDD) films. The morphology, growth direction, and crystallinity of the ZnO NRs were studied by scanning electron microscopy, X-ray diffraction and cathodoluminescence. Electrical characterization of the ZnO NR/BBD heterostructures revealed characteristic p-n junction properties with an on/off ratio of about 50 at +/- 4 V and a small reverse leakage current approximately 1 microA. Moreover, the junctions showed an ideality factor around 1.0 at a low forward voltage from 0 to 0.3 V and about 2.1 for an increased voltage ranging from 1.2 to 3.0 V, being consistent with that of an ideal diode according to the Sah-Noyce-Shockley theory.

Controlled growth of ZnO/Zn₁-xPbxSe core-shell nanowires and their interfacial electronic energy alignment

ZnO/Zn(1-x)Pb(x)Se core-shell nanowires (NWs) have been synthesized by a solution based surface ion transfer method at various temperatures. The energy dispersive spectroscopic (EDS) mapping of single NWs suggests that the Zn, Pb and Se atoms are uniformly distributed in their shell layers. The ternary Zn(1-x)Pb(x)Se layers with tunable bandgaps extend the band-edge of optical absorption from 450 nm to 700 nm contrasting with the binary ZnSe layers. The ultraviolet photoelectron spectroscopic (UPS) analysis reveals a transition from the type I to type II band alignment when the x fraction decreases from 0.66 to the value of 0.36 in the nanoshell layers. This quantitative investigation of electronic energy levels at ZnO and Zn(1-x)Pb(x)Se interfaces indicates that the proper type II band alignment is well suited for photovoltaic energy conversion. The photovoltaic cells comprising a ZnO/Zn(1-x)Pb(x)Se nano-heterojunction with the optimized Pb content are expected to be more efficient than the devices sensitized by binary ZnSe or PbSe.

Triggered firing and atrial fibrillation in transgenic mice with selective atrial fibrosis induced by overexpression of TGF-β1

BACKGROUND

Calcium transient triggered firing (CTTF) is induced by large intracellular calcium (Ca(i)) transient and short action potential duration (APD). We hypothesized that CTTF underlies the mechanisms of early afterdepolarization (EAD) and spontaneous recurrent atrial fibrillation (AF) in transgenic (Tx) mice with overexpression of transforming growth factor β1 (TGF-β1).

METHODS AND RESULTS

MHC-TGFcys(33)ser Tx mice develop atrial fibrosis because of elevated levels of TGF-β1. We studied membrane potential and Ca(i)transients of isolated superfused atria from Tx and wild-type (Wt) littermates. Short APD and persistently elevated Ca(i) transients promoted spontaneous repetitive EADs, triggered activity and spontaneous AF after cessation of burst pacing in Tx but not Wt atria (39% vs. 0%, P=0.008). We were able to map optically 4 episodes of spontaneous AF re-initiation. All first and second beats of spontaneous AF originated from the right atrium (4/4, 100%), which is more severely fibrotic than the left atrium. Ryanodine and thapsigargin inhibited spontaneous re-initiation of AF in all 7 Tx atria tested. Western blotting showed no significant changes of calsequestrin or sarco/endoplasmic reticulum Ca(2+)-ATPase 2a.

CONCLUSIONS

Spontaneous AF may occur in the Tx atrium because of CTTF, characterized by APD shortening, prolonged Ca(i) transient, EAD and triggered activity. Inhibition of Ca(2+) release from the sarcoplasmic reticulum suppressed spontaneous AF. Our results indicate that CTTF is an important arrhythmogenic mechanism in TGF-β1 Tx atria.

Evaluation for the ecological quality status of coastal waters in East China Sea using fuzzy integrated assessment method

This research presented an evaluation for the ecological quality status (EcoQS) of three semi-enclosed coastal areas using fuzzy integrated assessment method (FIAM). With this method, the hierarchy structure was clarified by an index system of 11 indicators selected from biotic elements and physicochemical elements, and the weight vector of index system was calculated with Delphi-Analytic Hierarchy Process (AHP) procedure. Then, the FIAM was used to achieve an EcoQS assessment. As a result of assessment, most of the sampling stations demonstrated a clear gradient in EcoQS, ranging from high to poor status. Among the four statuses, high and good, owning a ratio of 55.9% and 26.5%, respectively, were two dominant statuses for three bays, especially for Sansha Bay and Luoyuan Bay. The assessment results were found consistent with the pressure information and parameters obtained at most stations. In addition, the sources of uncertainty in classification of EcoQS were also discussed.

Perivascular epithelioid cell tumor (PEComa) of gynecologic origin: a clinicopathological study of three cases

Perivascular epithelioid cell tumors (PEComas), occasionally associated with the tuberous sclerosis complex, are characterized by varying amounts of spindle and epithelioid cells with clear to eosinophilic cytoplasm that display immunoreactivity for melanocytic markers, most frequently HMB-45. Perivascular epithelioid cell tumor of gynecologic origin is very rare, and there have been only a few reported cases. This study describes the clinical, histological, and immunohistochemical features and prognoses of three cases of gynecologic origin. Two of the three tumors were confined to the uterus and one to the vagina. None of the patients had tuberous sclerosis complex. Immunohistochemistry indicated that all three cases expressed at least one melanocytic marker, and HMB45 was a positive marker for all of them. These markers can be found in both epithelial cells and spindle cells. Except for MiTF, which was located in the nucleus, all the other antibodies were located in the cytoplasm. The three cases have been followed up for 26, 22, and three months, respectively, with disease-free survival in all cases. We conclude that PEComas of gynecologic origin have morphological and immunohistochemical features of the PEComa family, which are rare and should be included in the differential diagnosis with other tumors. Until more cases of this rare tumor are evaluated with longer follow-up, firm criteria for malignancy remain uncertain.

Effect of feeding different sources of rumen-protected methionine on milk production and N-utilization in lactating dairy cows

Objectives of this study were to quantify production responses of lactating dairy cows to supplying absorbable Met as isopropyl-2-hydroxy-4-(methylthio)-butanoic acid (HMBi), or rumen-protected Met (RPM, Smartamine M; Adisseo, Alpharetta, GA) fed with or without 2-hydroxy-4-(methylthio)-butanoic acid (HMB), and to determine whether Met supplementation will allow the feeding of reduced dietary crude protein (CP). Seventy cows were blocked by parity and days in milk into 14 blocks and randomly assigned within blocks to 1 of the 5 dietary treatments based on alfalfa and corn silages plus high-moisture corn: 1 diet with 15.6% CP and no Met source (negative control); 3 diets with 15.6% CP plus 0.17% HMBi, 0.06% RPM + 0.10% HMB, or 0.06% RPM alone; and 1 diet with 16.8% CP and no Met supplement (positive control). Assuming that 50% of ingested HMBi was absorbed from the gastrointestinal tract and 80% of the Met in RPM was absorbed at intestine, the HMBi and RPM supplements increased metabolizable Met supply by 9 g/d and improved the Lys:Met ratio from 3.6 to 3.0. After a 2-wk covariate period during which all cows received the same diet, cows were fed test diets continuously for 12 wk. Diet did not affect dry matter intake (mean ± SD, 25.0±0.3 kg/d), body weight gain (0.59±0.2 kg/d), or milk yield (41.7±0.6 kg/d). However, feeding HMBi increased yield of energy-corrected milk and milk content of protein and solids-not-fat. Moreover, trends were observed for increased milk fat content and yield of fat and true protein on all 3 diets containing supplemental Met. Apparent N efficiency (milk N/N intake) was highest on the RPM treatment. Feeding 16.8% CP without a Met source elevated milk urea N and urinary excretion of urea N and total N and reduced apparent N efficiency from 34.5 to 30.2%, without improving production. Overall results suggested that feeding HMBi or RPM would give similar improvements in milk production and N utilization.

Small-conductance calcium-activated potassium channel and recurrent ventricular fibrillation in failing rabbit ventricles

RATIONALE

Fibrillation/defibrillation episodes in failing ventricles may be followed by action potential duration (APD) shortening and recurrent spontaneous ventricular fibrillation (SVF).

OBJECTIVE

We hypothesized that activation of apamin-sensitive small-conductance Ca(2+)-activated K(+) (SK) channels is responsible for the postshock APD shortening in failing ventricles.

METHODS AND RESULTS

A rabbit model of tachycardia-induced heart failure was used. Simultaneous optical mapping of intracellular Ca(2+) and membrane potential (V(m)) was performed in failing and nonfailing ventricles. Three failing ventricles developed SVF (SVF group); 9 did not (no-SVF group). None of the 10 nonfailing ventricles developed SVF. Increased pacing rate and duration augmented the magnitude of APD shortening. Apamin (1 μmol/L) eliminated recurrent SVF and increased postshock APD(80) in the SVF group from 126±5 to 153±4 ms (P<0.05) and from 147±2 to 162±3 ms (P<0.05) in the no-SVF group but did not change APD(80) in nonfailing group. Whole cell patch-clamp studies at 36°C showed that the apamin-sensitive K(+) current (I(KAS)) density was significantly larger in the failing than in the normal ventricular epicardial myocytes, and epicardial I(KAS) density was significantly higher than midmyocardial and endocardial myocytes. Steady-state Ca(2+) response of I(KAS) was leftward-shifted in the failing cells compared with the normal control cells, indicating increased Ca(2+) sensitivity of I(KAS) in failing ventricles. The K(d) was 232±5 nmol/L for failing myocytes and 553±78 nmol/L for normal myocytes (P=0.002).

CONCLUSIONS

Heart failure heterogeneously increases the sensitivity of I(KAS) to intracellular Ca(2+), leading to upregulation of I(KAS), postshock APD shortening, and recurrent SVF.

Thymidine kinase 1 is a potential marker for prognosis and monitoring the response to treatment of patients with breast, lung, and esophageal cancer and non-Hodgkin's lymphoma

Thymidine kinase 1 (TK1) is converting thymidine to thymidine monophosphate, and is related to DNA replication and cell proliferation. The use of the TK1 protein levels as a proliferation marker in malignancies is here summarized. TK1 protein in serum (STK1p) and TK1 expression in tissues were determined by a chemoluminescent dot blot assay and by immunohistochemistry staining, respectively. The expression of TK1 in tumor tissues correlated to pathological stages and clinical grades of carcinomas (ca) of esophagus, lung and in premalignancy of breast ductal ca. STK1p could monitor the out-come of tumor therapy by being correlated to remission [breast ca, non-Hodgkin's lymphoma], relapse [breast ca] and to survival [non-Hodgkin's lymphoma] of patients. In a health screening study of 12,641 persons, STK1p seemed to predict the risk of development of neoplasia related diseases at early stage.