[Renal insufficiency and venous thromboembolism].

Venous thromboembolism (VTE) is of high incidence and prevalence worldwide. Renal insufficiency has high disease burden with insidious development and is accompanied with disorder of coagulation system. A higher prevalence of VTE has been observed among patients with renal insufficiency whereas VTE patient with renal insufficiency had higher rates of adverse outcomes. Recent evidence indicated that renal insufficiency was an important risk factor for both short and long-term prognosis for VTE. Renal function also affects the choice of anticoagulation therapy and dosage adjustment of drugs. We conducted a comprehensive review of the pathogenesis, mechanism, prognosis and treatment strategy for VTE patients who comorbid renal insufficiency by searching the latest and most advanced national and international articles, to provide integrated information for the prevention and treatment for VTE patients.

Overexpression of long noncoding RNA HOXC13-AS and its prognostic significance in hepatocellular carcinoma.

OBJECTIVE: The long noncoding RNA HOXC13 antisense RNA (HOXC13-AS) was overexpressed in several tumor specimens, and its overexpression was correlated with cells metastasis of tumors. However, its effects in other tumors remained largely unclear. In this work, we aimed to identify whether HOXC13-AS was abnormally expressed in hepatocellular carcinoma (HCC) and further explore its prognostic value. PATIENTS AND METHODS: QRT-PCR was applied for the examination of HOXC13-AS levels in 197 paired HCC specimens and matched non-tumor specimens. Chi-square tests were carried out for the verification of the relations between the levels of HOXC13-AS and the clinicopathologic features of HCC patients. The Kaplan-Meier methods were applied for the exploration of the prognostic value of HOXC13-AS. Multivariate analysis was performed using the Cox proportional hazard assays. RESULTS: Up-regulation of HOXC13-AS was observed in HCC tissues compared to matched normal tissues (p < 0.01). Higher levels of HOXC13-AS were associated with TNM stage (p = 0.024) and lymph node metastasis (p = 0.043). Survival assays showed that HCC patients with high-HOXC13-AS expressions had significantly shorter overall survival (p < 0.0106) and disease-free survival (p < 0.0066) compared to their counterparts with low-HOXC13-AS expressions. Multivariate analyses suggested HOXC13-AS as an independent prognostic factor for HCC patients. CONCLUSIONS: We showed that HOXC13-AS might serve as a promising biomarker for prognosis prediction of HCC.

Analysis of Forensic Sciences Literature in SCIE from 2008 to 2017.

OBJECTIVES: To analyze the literature on forensic sciences indexed in Science Citation Index Expanded （SCIE） in recent 10 years, and to understand the research status, characteristics and trends in the field of forensic sciences. METHODS: Literature on forensic sciences from 2008 to 2017 in Web of Science （WoS） was retrieved. The documents number and geographical distribution, document types, source titles, organizations, research areas, authors, funding agencies, and the high cited articles were detected. The impact factors （IF） of journals were retrieved in Journal Citation Reports （JCR）. The data were analyzed with descriptive statistics. RESULTS: From 2008 to 2017, there were 21 001 documents on forensic sciences in SCIE. The main document type was articles, with English as the major language. With regards to research areas, pathology has the largest number of papers worldwide, and genetics and heredity has the largest number of publications in mainland China. Among the 18 journals where the documents was published, Forensic Science International ranks the first on publication count, and Forensic Science International Genetics has the highest IF （5.637） in the JCR 2017. In 2017, the number of papers from mainland China increased by 48.50% compared with 2016, which was higher than the global increase （32.63%） and the top-5 countries in terms of number of publications （the US, Germany, the UK, Australia, Italy）. The average document count per organization is 1.98 worldwide and 1.17 in mainland China, respectively. The publication number per author is 0.53 worldwide and 0.36 in mainland China, respectively. Around 28.17% of the publications were funded, with National Natural Science Foundation of China （NSFC） as the Top 1 funding agency （192 papers）. Among the documents with citations, the most cited publication has been cited for 366 times. CONCLUSIONS: The yearly numbers of publications on forensic sciences are increasing during recent 10 years. Focusing on the mainland China, there would be more high-quality papers with the steady funding of NSFC.

Long noncoding RNA LINC01510 is highly expressed in colorectal cancer and predicts favorable prognosis.

OBJECTIVE: Long noncoding RNAs (lncRNAs) have recently emerged as important regulators in governing fundamental biological processes, as well as in tumorigenesis. LncRNA LINC01510 (LINC01510) was recently shown to be involved in colorectal cancer (CRC); however, its role in CRC remains unknown. The objective of this study was to evaluate LINC01510 expression and its relevance to the prognosis of CRC. PATIENTS AND METHODS: LINC01510 expression was detected in CRC tissues and cell lines by using quantitative real-time PCR (qRT-PCR). The correction between LINC01510 expression and clinical characteristics was evaluated with x2-test. Survival curves and log-rank test were used to analyze patients' survival. A Cox proportional hazard model was constructed to evaluate the association of LINC01510 expression with overall survival and disease-free survival, respectively. RESULTS: Here, we found that the levels of LINC01510 in CRC tissues were significantly higher than those in matched tumor-adjacent tissues. Moreover, high LINC01510 expression was observed to be closely correlated with histology/differentiation (p = 0.001), depth of invasion (p = 0.004) and TNM stage (p = 0.003). From the Kaplan-Meier survival curves, it was observed that patients with high expression of LINC01510 had shorter overall survival (p = 0.004) and disease-free survival (p = 0.000) as compared with the LINC01510-low group. In the multivariate analysis, high LINC01510 expression was an independent prognostic factor for both overall survival (p = 0.001) and disease-free survival (p = 0.001). CONCLUSIONS: We demonstrated that low LINC01510 expression was associated with the progression of CRC and could serve as a potential independent prognostic biomarker for patients with CRC.

Predictive values of FAP and HGF for tumor angiogenesis and metastasis in colorectal cancer.

This study aims to explore the correlation of hepatocyte growth factor (HGF) and fibroblast activation protein (FAP) expressions with the angiogenesis and metastasis in colorectal cancer (CRC). The immunohistochemical SABC method was used to detect HGF and FAP expressions in 127 CRC tissues, 51 colorectal polyp tissues and 28 normal tissues. HGF and FAP expressions in liver metastasis were detected using western blot to analyze the correlation of their expressions with lymph node metastasis and liver metastasis. Micro-vessel density (MVD) and clinic-pathologic information of CRC patients were recorded and analyzed. In CRC group, HGF and FAP expressions were greatly higher than those in normal group and colorectal polyps group (P < 0.05). Moreover, the positive rates of HGF and FAP expressions in lymph node metastasis were evidently higher than those in non-lymph node metastasis (P < 0.05). In liver metastasis group, HGF and FAP expressions were obviously higher than non-liver metastasis group (P < 0.05). CRC group had much more MVD in comparison with normal group and colorectal polyps group (P < 0.05).When compared with negative group, MVD was significantly higher than that in CRC tissue with positive HGF and FAP (P < 0.05). Spearman rank correlation analysis showed that HGF and FAP were in positive correlation with MVD (r = 0.542, P < 0.001; r = 0.753, P < 0.001). These results indicate that FAP and HGF play an important role in CRC angiogenesis, and their expression levels are valuable to predict CRC liver metastasis and lymph node metastasis.

The inhibitory actions by lacosamide, a functionalized amino acid, on voltage-gated Na+ currents.

The effect of lacosamide (LCS), a functionalized molecule with anti-convulsant properties, on ion channels was investigated, with the aid of patch clamp technology and simulation modeling. In NSC-34 neuronal cells, LCS was found to block voltage-gated Na(+) current (INa) in a frequency- and concentration-dependent manner. With the two-step voltage protocol, a minimal change in the steady-state inactivation of INa was found in the presence of LCS. However, with repetitive stimulation, the pulse-to-pulse reduction in peak current was shown to be exponential, with a rate linearly related to both the inter-stimulus interval and the LCS concentration. In addition, the frequency-dependent blocking properties were modeled by considering the drug interaction with a voltage-dependent mixture of NaV channels harboring either an accessible or an inaccessible binding site. LCS also increased the dimension of inactivation space of NaV-channel states, thereby producing the adaptive response of neurons to previous firing. LCS (30 µM) had no effects on the non-inactivating component of INa, while it slightly decreased the amplitude of delayed-rectifier K(+) current. Moreover, LCS suppressed the peak amplitude of INa in embryonic cortical neurons. In human embryonic kidney (HEK293T) cells which expressed SCN5A, LCS attenuated the peak amplitude of INa, in a concentration-dependent fashion. The unique effects of LCS on NaV currents presented here may contribute to its in vivo modulation of cellular excitability.

Underlying mechanism of regulatory actions of diclofenac, a nonsteroidal anti-inflammatory agent, on neuronal potassium channels and firing: an experimental and theoretical study.

Diclofenac (DIC), a nonsteroidal anti-inflammatory drug, is known to exert anti-nociceptive and anti-convulsant actions; however, its effects on ion currents, in neurons remain debatable. We aimed to investigate (1) potential effects of diclofenac on membrane potential and potassium currents in differentiated NSC-34 neuronal cells and dorsal root ganglion (DRG) neurons with whole-cell patch-clamp technology, and (2) firing of action potentials (APs), using a simulation model from hippocampal CA1 pyramidal neurons based on diclofenac's effects on potassium currents. In the NSC-34 cells, diclofenac exerted an inhibitory effect on delayed-rectifier K⁺ current (I(KDR)) with an IC50 value of 73 µM. Diclofenac not merely inhibited the I(KDR) amplitude in response to membrane depolarization, but also accelerated the process of current inactivation. The inhibition by diclofenac of IK(DR) was not reversed by subsequent application of either naloxone. Importantly, diclofenac (300 µM) increased the amplitude of M-type K⁺ current (I)(KM)), while flupirtine (10 µM) or meclofenamic acid (10 µM) enhanced it effectively. Consistently, diclofenac (100 µM) increased the amplitude of I(KM) and diminished the I(KDR) amplitude, with a shortening of inactivation time constant in DRG neurons. Furthermore, by using the simulation modeling, we demonstrated the potential electrophysiological mechanisms underlying changes in AP firing caused by diclofenac. During the exposure to diclofenac, the actions on both I(KM) and I(KDR) could be potential mechanism through which it influences the excitability of fast-spiking neurons. Caution needs to be made in attributing the effects of diclofenac primarily to those produced by the activation of I(KM).

Electrophysiological characterization of sodium-activated potassium channels in NG108-15 and NSC-34 motor neuron-like cells.

AIMS: The electrical properties of Na(+) -activated K(+) current (I(K(Na)) ) and its contribution to spike firing has not been characterized in motor neurons. METHODS: We evaluated how activation of voltage-gated K(+) current (I(K) ) at the cellular level could be coupled to Na(+) influx through voltage-gated Na(+) current (I(N) (a) ) in two motor neuron-like cells (NG108-15 and NSC-34 cells). RESULTS: Increasing stimulation frequency altered the amplitudes of both I(Na) and I(K) simultaneously. With changes in stimulation frequency, the kinetics of both I(Na) inactivation and I(K) activation were well correlated at the same cell. Addition of tetrodotoxin or ranolazine reduced the amplitudes of both I(Na) and I(K) simultaneously. Tefluthrin (Tef) increased the amplitudes of both I(Na) and I(K) throughout the voltages ranging from -30 to + 10 mV. In cell-attached recordings, single-channel conductance from a linear current-voltage relation was 94 ± 3 pS (n = 7). Tef (10 µm) enhanced channel activity with no change in single-channel conductance. Tef increased spike firing accompanied by enhanced facilitation of spike-frequency adaptation. Riluzole (10 µm) reversed Tef-stimulated activity of K(Na) channels. In motor neuron-like NSC-34 cells, increasing stimulation frequency altered the kinetics of both I(Na) and I(K) . Modelling studies of motor neurons were simulated to demonstrate that the magnitude of I(K(Na)) modulates AP firing. CONCLUSIONS: There is a direct association of Na(+) and K(Na) channels which can provide the rapid activation of K(Na) channels required to regulate AP firing occurring in motor neurons.

Modification of activation kinetics of delayed rectifier K+ currents and neuronal excitability by methyl-ß-cyclodextrin.

The effects of methyl-ß-cyclodextrin (MßCD), an oligosaccharide, on ion currents were investigated in differentiated NG108-15 neuronal cells. In NG108-15 cells treated with dibutyryl cyclic AMP, the expression level of the K(V)3.1 mRNA was elevated. Depletion of membrane cholesterol by exposing cells to MßCD (1 mM) resulted in a significant reduction of the activation kinetics of delayed rectifier K(+) current (I(K)((DR))) in these cells. However, neither activation nor inactivation curve of I(K(DR)) was altered following MßCD treatment. In current-clamp recordings, in MßCD-treated cells, the instantaneous frequency of the firing in response to long-lasting current stimuli was reduced. In a modified Hodgkin-Huxley neuron, the upward shift in the relationship of activation/deactivation time constant of I(K(DR)) versus membrane potential causes a reduction of I(K(DR)) amplitude accompanied by an increase in the width of action potentials. In the studies from a high-frequency modeled neuron, reduction of voltage-dependent activation of I(K(DR)) can also facilitate spike-frequency adaptation. In a simulated network of spiking neurons, the increased activation/deactivation time constant of I(K(DR)) slowed repetitive firing. Taken together, MßCD may slow activation kinetics of I(K(DR)) and confer a trigger for the propensity to develop spike-frequency adaptation in neurons or neuroendocrine cells.

Dexmedetomidine, an alpha2-adrenergic agonist, inhibits neuronal delayed-rectifier potassium current and sodium current.

BACKGROUND: Dexmedetomidine (DEX), a selective agonist of alpha2-adrenergic receptors, is recognized to facilitate analgesia and anaesthesia in humans. Despite the potential for wide use, its effects on ion currents and membrane potential in neurones remain largely unclear. METHODS: We investigated the effects of DEX on ion channels in NG108-15 neuronal cells differentiated with dibutyryl cyclic AMP and in cultured cerebellar neurones. RESULTS: DEX suppressed the amplitude of delayed rectifier K+ current [I(K(DR))] in a concentration-dependent manner with an IC50 value of 4.6 microM in NG108-15 cells. No change in the steady-state inactivation of I(K(DR)) was evident in the presence of DEX. A minimal binding scheme was also used to evaluate DEX-induced block of I(K(DR)). Inhibition of I(K(DR)) by DEX was still observed in cells preincubated with yohimbine (10 microM) or efaroxan (10 microM). DEX depressed the peak amplitude of Na+ current (I(Na)), whereas it had minimal effect on L-type Ca2+ current. Under current-clamp configuration, DEX increased the duration of action potentials (APs). I(K(DR)) and I(Na) in response to AP waveforms were more sensitive to block by DEX than those elicited during rectangular pulses. In isolated cerebellar granule cells, DEX also effectively suppressed I(K(DR)). CONCLUSIONS: The effects of DEX are not limited to its interactions with alpha2-adrenergic receptors. Inhibitory effects on I(K(DR)) and I(Na) constitute one of the underlying mechanisms through which DEX and its structurally related compounds might affect neuronal activity in vivo.

Impaired endothelial function in hypertensive patients with target organ damage.

To evaluate the correlation between endothelial dysfunction and multiple target organ damage (TOD), we measured endothelial function using high-resolution ultrasonography in hypertensive patients with or without TOD. Two hundred and eighty patients with hypertension were divided into four groups as follows: no TOD (Group I, n=61); 1 TOD (Group II, n=113); 2 TOD (Group III, n=59); and >or=3 TOD (Group IV, n=47). Endothelial function was assessed by endothelium-dependent flow-mediated dilatation (FMD) and -independent vasodilation (after sublingual administration of nitroglycerin) of the brachial artery using high-resolution vascular ultrasound. We also assessed the intima-media thickness (IMT) of the common carotid, carotid to femoral pulse wave velocity (cf-PWV) and left ventricular mass index (LVMI). FMD was inversely associated with the number of affected organs. FMD was lower in the patient groups with >or=3 TOD (Group IV: 6.85+/-4.70% vs Group II: 10.00+/-6.15%, P<0.01), 2 TOD (Group III: 7.37+/-5.02% vs Group II, P<0.01) and 1 TOD as compared with patients with no TOD (Group I: 11.88+/-7.11% vs Group II, P<0.05). In univariate correlation analysis, there was a significant relationship between FMD and IMT, serum creatinine, LVMI and cf-PWV. In stepwise multivariate regression analysis, FMD still correlated with waist size (beta=-0.283, P<0.01), age (beta=-0.231, P<0.05) and IMT (beta=-0.197, P=0.05). These findings suggested that reduced FMD was associated with the number of TOD and may be considered an indicator for evaluating TOD.

Experimental and simulation studies on the mechanisms of levetiracetam-mediated inhibition of delayed-rectifier potassium current (KV3.1): contribution to the firing of action potentials.

Levetiracetam (LEV) is an S-enantiomer pyrrolidone derivative with established antiepileptic efficacy in generalized epilepsy and partial epilepsy. However, its effects on ion currents and membrane potential remain largely unclear. We investigated the effect of LEV on differentiated NG108-15 neurons. In these cells treated with dibutyryl cyclic AMP, the expression level of the K(V)3.1 mRNA was elevated. With the aid of patch clamp technology, we found that LEV could suppress the amplitude of delayed rectifier K(+) current (I(K(DR))) in a concentration-dependent manner with an IC(50) value of 37 microM. LEV (30 microM) shifted the steady-state activation of I(K(DR)) to a more positive potential by 10 mV, without shifting the steady-state inactivation of I(K(DR)). Neither Na(+), nor erg (ether-a-go-go-related)-mediated K(+) and ATP-sensitive K(+) currents were affected by LEV (100 microM). LEV increased the duration of action potentials in current clamp configuration. Simulation studies in a modified Hodgkin-Huxley neuron and network unraveled that the reduction of slowly inactivating I(K(DR)) resulted in membrane depolarization accompanied by termination of the firing of action potentials in a stochastic manner. Therefore, the inhibitory effects on slowly inactivating I(K(DR)) (K(V)3.1-encoded current) may constitute one of the underlying mechanisms through which LEV affect neuronal activity in vivo.

Evidence for state-dependent block of DPI 201-106, a synthetic inhibitor of Na+ channel inactivation, on delayed-rectifier K+ current in pituitary tumor (GH3) cells.

DPI 201-107 (DPI), a diphenylpiperazinylindole derivative, was reported to be a cardio-selective modifier of voltage-gated Na+ channels. It remains unclear whether DPI has any effects on ion currents. The effects of DPI on ion currents and membrane potential in pituitary tumor (GH3) cells were investigated in this study. DPI (1-100 microM) suppressed the amplitude of delayed-rectifier K+ current (I(K(DR))) in a concentration-dependent manner with an IC(50) value of 9.4 microM. The presence of DPI also enhanced the rate and extent of I(K(DR)) inactivation. Recovery from block by DPI (10 microM) was fitted by a single exponential. Crossover of tail currents during the exposure to DPI was also observed. Under current-clamp recordings, DPI prolonged action potential duration in GH3 cells. With a minimal binding scheme, DPI-induced block of I(K(DR))) was quantitatively provided. The exposure to DPI also blocked I(K(DR))) with a concomitant increase in current inactivation in NG108-15 neuronal cells. Taken together, the results imply that DPI acts as an open-channel blocker of delayed-rectifier K+ channels in these cells. The widening of action potentials induced by DPI in these cells may be explained mainly by its block of I(K(DR))) in a state-dependent manner.

Properties of BK(Ca) channels in oral keratinocytes.

Keratinocytes are important for epithelial antimicrobial barrier function. The activity of ion channels can affect the proliferation of keratinocytes. Little is known about Ca2+-activated K+ currents in these cells. Ion currents in normal human oral keratinocytes were characterized with a patch-clamp technique. In whole-cell configuration, depolarizing pulses evoked K+ outward currents (I(K)) in oral keratinocytes. Iberiotoxin (200 nM) and paxilline (1 microM) suppressed I(K); however, neither apamin (200 nM) nor 5-hydroxydecanoate (30 microM) had any effects on it. Caffeic acid phenethyl ester, a compound of honeybee propolis, increased I(K) with an EC50 value of 12.8 +/- 1.2 microM. In inside-out patches, a BK(Ca) channel was observed in keratinocytes, but not in oral squamous carcinoma (OCE-M1) cells. Caffeic acid phenethyl ester or cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate applied to the intracellular surface of a detached patch increased BK(Ca)-channel activity. The results demonstrate that the properties of BK(Ca) channels in normal human oral keratinocytes are similar to those described in other types of cells. Caffeic acid derivatives can also stimulate BK(Ca)-channel activity directly.

Stimulation of the BK(Ca) channel in cultured smooth muscle cells of human trachea by magnolol.

BACKGROUND: Magnolol, a compound isolated from the cortex of Magnolia officinalis, has been found to possess anti-allergic and anti-asthmatic activity. METHODS: The effect of magnolol on ionic currents was studied in cultured smooth muscle cells of human trachea with the aid of the patch clamp technique. RESULTS: In whole cell current recordings magnolol reversibly increased the amplitude of K+ outward currents. The increase in outward current caused by magnolol was sensitive to inhibition by iberiotoxin (200 nM) or paxilline (1 microM) but not by glibenclamide (10 microM). In inside out patches, magnolol added to the bath did not modify single channel conductance but effectively enhanced the activity of large conductance Ca2+ activated K+ (BK(Ca)) channels. Magnolol increased the probability of these channel openings in a concentration dependent manner with an EC50 value of 1.5 microM. The magnolol stimulated increase in the probability of channels opening was independent of internal Ca2+. The application of magnolol also shifted the activation curve of BK(Ca) channels to less positive membrane potentials. The change in the kinetic behaviour of BK(Ca) channels caused by magnolol in these cells is the result of an increase in dissociation and gating constants. CONCLUSIONS: These results provide evidence that, in addition to the presence of antioxidative activity, magnolol is potent in stimulating BK(Ca) channel activity in tracheal smooth muscle cells. The direct stimulation of these BK(Ca) channels by magnolol may contribute to the underlying mechanism by which it acts as an anti-asthmatic compound.

Fenamates stimulate BKCa channel osteoblast-like MG-63 cells activity in the human.

BACKGROUND: The fenamates, a family of nonsteroidal anti-inflammatory drugs that are derivatives of N-phenylanthranilic acid, are the inhibitors of cyclo-oxygenase. The ionic mechanism of actions of these compounds in osteoblasts is not well understood. METHODS: The effects of the fenamates on ionic currents were investigated in a human osteoblast-like cell line (MG-63) with the aid of the whole-cell and inside-out configurations of the patch-clamp technique. RESULTS: In MG-63 cells, niflumic acid and meclofenamic acid increased K+ outward currents (IK). The niflumic acid-stimulated IK was reversed by subsequent application of iberiotoxin or paxilline, yet not by that of glibenclamide or apamin. In the inside-out configuration, niflumic acid (30 micromol/L) added to the bath did not modify single-channel conductance but increased the activity of large-conductance Ca2+-activated K+ (BKCa) channels. The EC50 values for niflumic acid- and meclofenamic acid-induced channel activity were 22 and 24 micromol/L, respectively. Niflumic acid (30 micromol/L) and meclofenamic acid (30 micromol/L) shifted the activation curve of BKCa channels to less positive membrane potentials. Membrane stretch potentiated niflumic acid-stimulated channel activity. The rank order of potency for the activation of BKCa channels in these cells was niflumic acid = meclofenamic acid > tolfenamic acid > flufenamic acid > nimesulide. Evans blue and nordihydroguaiaretic acid increased channel activity; however, indomethacin, piroxicam, and NS-398 had no effect on it. CONCLUSIONS: The fenamates can stimulate BKCa channel activity in a manner that seems to be independent of the action of these drugs on the prostaglandin pathway. The activation of the BKCa channel may hyperpolarize the osteoblast, thereby modulating osteoblastic function.

Quantitative analysis of end-tidal carbon dioxide during mechanical and spontaneous ventilation in infants and young children.

Capnography provides a substitute for monitoring of arterial carbon dioxide tension (PCO(2)). We performed a prospective study to evaluate a new application of capnography, using quantitative curve analysis in the pediatric ICU. Twenty-five infants and children admitted to the pediatric ICU after cardiovascular surgery for congenital heart diseases were included in the study. Capnographic curves were recorded during 3 phases of mechanical and spontaneous ventilation: phase 1, immediate postoperative period; phase 3, preextubation period; and phase 2, period between phases 1 and 3. Each recording included 17 sec of capnographic tracings from consecutive spontaneous and/or ventilator-driven breaths. Quantitative curve analysis was made to define parameters including peak value of exhaled PCO(2) (P), mean rate of rise of PCO(2) (R), and area under each capnographic curve (A). Qualitative inspection of the wave contour showed no obvious difference in phase 3 during spontaneous and mechanically assisted ventilator breaths. However, an obvious difference existed between spontaneous and mechanically assisted breaths in phase 2. For each parameter (P, R, and A), there was a significant difference in phases 2 and 3 from spontaneous breaths. However, there was no significant difference in phases 2 and 3 from ventilator-assisted breaths. We further calculated the ratio of parameters of spontaneous breaths (S) and ventilator-assisted breaths (V) in phase 2 and phase 3. The ratio of S/V for P, R, and A showed significant differences between phase 2 and phase 3. We conclude that quantitative analysis of exhaled end-tidal PCO(2) curves revealed significant changes of specific parameters during the transition from the ventilator-dependent state to the spontaneously breathing ventilator-independent state. This new approach provides a new way to estimate respiratory status in infants and children receiving ventilator therapy. Through quantitative capnographic curve analysis, if P, R, and A from spontaneous breaths approached those of ventilator-assisted breaths, patients have resumed reasonable pulmonary mechanics, and extubation may then be considered.

Rutaecarpine-induced block of delayed rectifier K+ current in NG108-15 neuronal cells.

The effects of rutaecarpine on ionic currents of NG108-15 neuronal cells were investigated in this study. Rutaecarpine (2-100 microM) suppressed the amplitude of delayed rectifier K+ current (I(K(DR))) in a concentration-dependent manner. The IC50 value for rutaecarpine-induced inhibition of I(K(DR)) was 11 microM. I(K(DR)) present in these cells is sensitive to the inhibition by quinidine and dendrotoxin, yet not by E-4031. The presence of rutaecarpine enhanced the rate and extent of I(K(DR)) inactivation, although it had no effect on the initial activation phase of I(K(DR)). Recovery from block by rutaecarpine (5 microM) was fitted by a single exponential with a value of 2.87 s. Crossover of tail currents in the presence of rutaecarpine was also observed. Cell-attached single-channel recordings revealed that rutaecarpine decreased channel activity, but it did not alter single-channel amplitude. With the aid of the binding scheme, a quantitative description of the rutaecarpine actions on I(K(DR)) was provided. However, rutaecarpine (20 microM) had no effect on L-type Ca2+ current. Under current-clamp configuration, rutaecarpine prolonged action potential duration in NG108-15 cells. These results show that rutaecarpine is a blocker of the K(DR) channel. The increase in action potential duration induced by rutaecarpine can be explained mainly by its blocking actions on I(K(DR)).

Ceramide inhibits the inwardly rectifying potassium current in GH(3) lactotrophs.

The effects of ceramide on ion currents in rat pituitary GH(3) cells were investigated. Hyperpolarization-elicited K(+) currents present in GH(3) cells were studied to determine the effect of ceramide and other related compounds on the inwardly rectifying K(+) current (I(K(IR))). Ceramide (C(2)-ceramide) suppressed the amplitude of I(K(IR)) in a concentration-dependent manner, with an IC(50) value of 5 microM. Ceramide caused a rightward shift in the midpoint for the activation curve of I(K(IR)). Pretreatment with PD-98059 (30 microM) or U-0126 (30 microM) did not prevent ceramide-mediated inhibition of I(K(IR)). However, the magnitude of ceramide-induced inhibition of I(K(IR)) was attenuated in GH(3) cells preincubated with dithiothreitol (10 microM). TNF alpha (100 ng/g) also suppressed I(K(IR)). In the inside-out configuration, application of ceramide (30 microM) to the bath slightly suppressed the activity of large conductance Ca(2+)-activated K(+) channels. Under the current clamp mode, ceramide (10 microM) increased the firing of action potentials. Cells that exhibited an irregular firing pattern were converted to those displaying a regular firing pattern after application of ceramide (10 microM). Ceramide also suppressed I(K(IR)) in neuroblastoma IMR-32 cells. Therefore, ceramide can produce a depressant effect on I(K(IR)). The blockade of this current by ceramide may affect cell function.

Inhibition of large-conductance calcium-activated potassium channel by 2-methoxyestradiol in cultured vascular endothelial (HUV-EC-C) cells.

2-Methoxyestradiol, an endogenous metabolite of 17beta-estradiol, is known to have antitumor and antiangiogenic actions. The effects of 2-methoxyestradiol on ionic currents were investigated in an endothelial cell line (HUV-EC-C) originally derived from human umbilical vein. In the whole-cell patch-clamp configuration, 2-methoxyestradiol (0.3-30 microm) reversibly suppressed the amplitude of K+ outward currents. The IC50 value of the 2-methoxyestradiol-induced decrease in outward current was 3 microm. Evans blue (30 microm) or niflumic acid (30 microm), but not diazoxide (30 microm), reversed the 2-methoxyestradiol-induced decrease in outward current. In the inside-out configuration, application of 2-methoxyestradiol (3 microm) to the bath did not modify the single-channel conductance of large-conductance Ca2+-activated K+ (BKCa) channels; however, it did suppress the channel activity. 2-Methoxyestradiol (3 microm) produced a shift in the activation curve of BKCa channels to more positive potentials. Kinetic studies showed that the 2-methoxyestradiol-induced inhibition of BKCa channels is primarily mediated by a decrease in the number of long-lived openings. 2-Methoxyestradiol-induced inhibition of the channel activity was potentiated by membrane stretch. In contrast, neither 17beta-estradiol (10 microm) nor estriol (10 microm) affected BKCa channel activity, whereas 2-hydroxyestradiol (10 microm) slightly suppressed it. Under current-clamp condition, 2-methoxyestradiol (10 microm) caused membrane depolarization and Evans blue (30 microm) reversed 2-methoxyestradiol-induced depolarization. The present study provides evidence that 2-methoxyestradiol can suppress the activity of BKCa channels in endothelial cells. These effects of 2-methoxyestradiol on ionic currents may contribute to its effects on functional activity of endothelial cells.