Rise To Cl Research Articles

A highly sensitive, long-time stable Ag/AgCl ultra-micro sensor for in situ monitoring chloride ions inside the crevice using SECM

Tracking the variation of Cl− timely within the crevice is of great significance for comprehending the dynamic mechanism of crevice corrosion. The reported chloride ion selective electrodes are difficult to realize the long-time Cl− detection inside the confined crevice, due to their millimeter size or a relative limited lifespan. For this purpose, an Ag/AgCl ultra-micro sensor (UMS) with a radius of 12.5 μm was fabricated and optimized using laser drawing and electrodeposition techniques. Results show the AgCl film's structure is significantly impacted by the deposited current density, and further affects the linear response, life span and stability of Ag/AgCl UMS. The UMS prepared at current density of 0.1 mA/cm2 for 2 h shows a rapid response (several seconds), excellent stability and reproducibility, strong acid/alkali tolerance, sufficient linearity (R2 > 0.99), and long lifespan (86 days). Moreover, combined with the potentiometric mode of scanning electrochemical microscope (SECM), the Ag/AgCl UMS was successfully applied to monitor the in-situ radial Cl− concentration in micro-regions inside a 100 μm gap of stainless steel. The findings demonstrated that there was obvious radial difference in Cl− concentration inside the crevice, where the fastest rise in Cl− concentration was at the opening. The proposed method which combines the UMS with SECM has attractive practical applications for microzone Cl− monitoring in real time inside crevice. It may further promote the study of other localized corrosion mechanism and the development of microzone ions detection method.

A comparative study of electrodeposition and sodium dithionite reduction for recovering gold in gold-rich solution from the adsorption of thiosulfate solution by ion exchange resin

A comparative study was performed on electrodeposition and sodium dithionite reduction for recovering gold in the gold-rich solution from the adsorption of thiosulfate solution by ion exchange resin. Using electrodeposition method, gold started to deposit when the potential was lower than −100 mVHg/HgO. The rise of Cl− concentration improved gold deposition while the increases of SO32− and S2O32− concentrations were unbeneficial to gold deposition. When the solution was deposited at the optimum potential of −600 mVHg/HgO for 5 h, the gold deposition percentage reached 99.33 %. With sodium dithionite reduction method, the gold reduction percentage achieved 100 % after only 5 min as S2O42− dosage was eight times of the theoretical amount. The increases of SO32− and S2O32− concentrations hindered gold reduction while the augment of Cl− concentration had no obvious effect. Overall, sodium dithionite reduction method has the advantages of shorter reaction time, higher gold recovery percentage, better solution stability and lower recovery cost, and thus it has a broader industrial application prospect.

Effects of saline immersion on the physiological alterations of grass goldfish (Carassius auratus) during subsequent recovery in freshwater

The present work aims to evaluate the tolerance, osmoregulation, metabolism, and antioxidant ability of saline water immersed grass goldfish (Carassius auratus) during the recovery in freshwater. Grass goldfish (38.15 ± 5.48g) acclimated in freshwater were immersed by salinities (0‰, 20‰ and 30‰) for different time durations (10, 20, 30 and 60 min); and the physiological responses were measured during freshwater recovery. The blood osmolalities were not significantly different at any group fish, while whereas the decline of Na+ concentration and the ratio of Na+/Cl- as well as the rise of Cl- concentration was observed in saline treated fish. Soon after freshwater recovery, the transcription of NKA-α and NKA-β mRNA in gills of salinity 20 immersed fish elevated significantly and then decreased, whereas no obvious changes were detected in salinity 30 treated fish. Till 24h post freshwater recovery, gill Na+/K+-ATPase activities in saline treated fish were lower than control group except for the fish immersed by salinity 20 for 10-30 min. At 24h of recovery, cortisol levels in salinity 20 immersed fish were lower than salinity 30 treated fish, but remained higher than control. As for serum lactic acid, fish treated by salinity 20 for 10 or 20 min did not show any fluctuation. However, higher lactic acid contents were detected in all other five salinity treated groups during recovery. Generally, at 24 h of recovery, salinity 20 treated fish exhibited higher SOD and CAT activities than fish immersed by salinity 30. In summary, grass goldfish could survive by immersion in salinity 20 less than 60 min or salinity 30 less than 30min, even though immersion by salinity 20 could minimize the negative effects.

Singlet oxygen-dominated electrocatalytic oxidation treatment for the high-salinity quaternary ammonium compound wastewater with Ti/(RuxIry)O2 anode

The widespread application of quaternary ammonium compounds (QAC) has posed a serious hazard to the environment and human being, and high concentration of Cl− in QAC wastewater may further increase the difficulty of pollutants elimination. In this study, such a QAC wastewater under high salinity conditions was chosen as the target, the prepared Ti/(RuxIry)O2 anode exhibited favorable catalytic performance for the oxidation and mineralization of QAC under high salinity conditions. Increasing the Ru/Ir ratio of Ti-based electrode coating also slightly promoted the inner catalytic capacity. The combination of electron paramagnetic resonance (EPR) and quenching experiments indicates that 1O2 served as a main reactive specie in the Ti/(RuxIry)O2 electrooxidation system. The increase of pH could decrease the removal efficiency of QAC for the reduced 1O2 yield, and the rise of Cl− concentration could favor the QAC oxidation, and Cl− was a better electrolyte to promote the oxidation of organic contaminants when compared to Na2SO4 or Na2CO3. Additionally, the conversion pathway of the model pollutant was tentatively investigated, the results demonstrated that there were almost no halogenated final products residual by electrocatalytic oxidation with Ti/(RuxIry)O2 anode. This study not only elucidate the reaction mechanism of Ti/(RuxIry)O2 anode electrocatalytic oxidation of high salinity QAC wastewater, but also may provide an efficacious and eco-friendly method for the treatment of high salinity QAC wastewater.

Seawater intrusion prone areas around Yogyakarta International Airport: a geological approach

Construction of Yogyakarta International Airport on Kulonprogo coastal areas can threaten the groundwater quality because it can cause seawater intrusion. The method in this study is by using a literature review. The purpose of this review is to investigate seawater intrusion prone areas around Yogyakarta International Airport based on a geological approach. The geological approach associated with seawater intrusion in the study site is a lithological characteristic. A lithological characteristic discussed in this study is the origin of the sand on Kulonprogo beach where the Yogyakarta International Airport is located. The elements used in the seawater intrusion test parameters are Na+, Ca2+, K+, Mg2+, CO3 2−, HCO3 −, Cl− and SO4 2−. A rise in Cl− was reported as suggesting the intrusion of seawater into the groundwater. But if only see the value of one of those elements, it cannot indicate seawater intrusion occurs in that area. The high element’s contents can arrive from the solution or weathering the lithological. This study is preliminary research, to assess seawater intrusion in the study site, it is necessary to conduct a groundwater geochemical test in the future.

Conceptual design and numerical studies of active flow control aerofoil based on shape-memory alloy and macro fibre composites

ABSTRACTActive flow control for aerofoils has been proven to be an effective way to improve the aerodynamic performance of aircraft. A conceptual hybrid design with surfaces embedded with Shape-Memory Alloy (SMA) and trailing Macro Fibre Composites (MFC) is proposed to implement active flow control for aerofoils. A Computational Fluid Dynamics (CFD) model has been built to explore the feasibility and potential performance of the proposed conceptual hybrid design. Accordingly, numerical analysis is carried out to investigate the unsteady flow characteristics by dynamic morphing rather than using classical static simulations and complicated coupling. The results show that camber growth by SMA action could cause an evident rise of Cl and Cd in the take-off/landing phases when the Angle-of-Attack (AoA) is less than 10°. The transient tail vibration behaviour in the cruise period when using MFC actuators is studied over wide ranges of frequency, AoA and vibration amplitude. The buffet frequency is locked in by the vibration frequency, and a decrease of 1.66–2.32% in Cd can be achieved by using a proper vibration frequency and amplitude.

Influence of temperature on corrosion resistance of austenitic stainless steel in cl− containing solutions

Abstract Temperature is considered a complicated external factor of the susceptibility of stainless steels to the pitting. This paper deals with the corrosion behaviour of AISI 316Ti stainless steel in temperature range 22 - 80°C in aggressive chloride environments (3 and 5% FeCl3 solutions). The corrosion resistance of tested steel is evaluated on the base of results of exposure immersion tests and cyclic potentiodynamic tests. According to the obtained results the resistance of AISI 316Ti to the pitting is markedly affected by temperature changes in the range 22 – 80°C. Intensity of corrosion attack increases with the rise of Cl− concentration. Gentle changes of temperature and Cl− concentration cause significant differences in character of local damage. The appearance of pitted surfaces changes with the rise of the temperature (a density of pitting increases, a size of pits decreases). The strongest change in appearance is observed between 40 and 50ºC.

Balanced versus unbalanced salt solutions: what difference does it make?

The infusion of crystalloid solutions is a fundamental part of the management of critically ill patients. These solutions are used to maintain the balance of water and essential electrolytes and replace losses when patients have limited gastrointestinal intake. They also act as carriers for intravenous infusion of medication and red cells. The most commonly used solution, 0.9% saline, has equal concentrations of Na(+) and Cl(-) even though the plasma concentration of Na(+) normally is 40meq/L higher than that of Cl(-). The use of this fluid thus can produce a hyperchloremic acidosis in a dose-dependent manner, but it is not known whether this has clinical significance. The first part of this article deals with the significance of Na(+) and Cl(-) in normal physiology. This begins with examination of their roles in the regulation of osmolality, acid-base balance, and generation of electrochemical gradients and why the concentration of Cl(-) normally is considerably lower than that of Na(+). The next part deals with how their concentrations are regulated by the gastrointestinal tract and kidney. Based on the physiology, it would seem that solutions in which the concentration of Na(+) is "balanced" by a substance other than Cl(-) would be advantageous. The final part examines the evidence to support that point. There are strong observational data that support the notion that avoiding an elevated Cl(-) concentration or using fluids that reduce the rise in Cl(-) reduces renal dysfunction, infections, and possibly even mortality. However, observational studies only can indicate an association and cannot indicate causality. Unfortunately, randomized trials to date are far too limited to address this crucial issue. What is clear is that appropriate randomized trials will require very large populations. It also is not known whether the important variable is the concentration of Cl(-), the difference in concentrations of Na(+) and Cl(-), or the total body mass of Cl(-).

混和材を用いたコンクリートおよびモルタル中の鉄筋発錆限界塩化物イオン濃度に関する研究

Considering environmental impact of construction materials, especially concrete, mineral admixtures like fly ash or blast furnace slag should be used as much as possible. Such concrete using mineral admixture generally has dense micro pore structure and high durability due to high resistance performance against the ingress of damage factors into concrete can be expected. However, as the chemical reaction of mineral admixtures consumes Ca(OH)2 in concrete, the pH value decreases with the age of concrete. Such dropping of pH value may decrease the critical chloride content for the initiation of steel corrosion in concrete. This study experimentally investigated the critical chloride content in some cases of concrete or mortar with mineral admixtures including the cases of combination of blast furnace slag cement and fly ash. As a result, although the combination of blast furnace slag cement and fly ash could realized highly dense pore structure, Cl-/OH- molar ratio in mortar pore solution extracted by high compressive pressure remarkably increased compared with the case of normal mortar because of the synergistic effect of reduction of OH- concentration and the rise of Cl- concentration. However, correlation between Cl-/OH- molar ratio and half-cell potential was not so clear, which suggested that Cl-/OH- molar ratio is not the unique factor to determine the initiation of steel corrosion.

Effect of Cl− on photosynthetic bicarbonate uptake in two cyanobacteria Microcystis aeruginosa and Synechocystis PCC6803

Photosynthetic inorganic carbon utilization was investigated in two cyanobacteria Microcystis aeruginosa and Synechocystis PCC6803 grown in standing culture. Photosynthetic rates for the two algae reached about 10 times the theoretical CO2 supply rate at low dissolved inorganic carbon (DIC) of 100 μmol/L, and the rates were unaffected by the addition of 20 mmol/L Na+, indicating that the two algae possessed Na+-independent HCO 3 − utilization for photosynthesis under low DIC. Their photosynthetic rates at low DIC were inhibited by higher Cl− and the degrees of inhibition were increased with the rise of Cl− concentration, and in the presence of Diphenylamine-2-carboxylate (DPC), a reported Cl− channel inhibitor, the rates decreased by 74%–82%, implying that putative DPC-sensitive Cl− channels participate in Na+-independent HCO 3 − uptake for photosynthesis. The experiment of intracellular 14C-DIC accumulation for photosynthesis showed that internal DIC pools decreased by about 80% with 200 μmol/L DPC and by 64%–70% with 100 mmol/L Cl−. The experiment of chlorophyll a fluorescence quenching showed that initial rates and extents of fluorescence quenching obviously decreased with 200 μmol/L DPC or 100 mmol/L Cl−. The two experiments gave further evidence that putative DPC-sensitive Cl− channels participate in Na+-independent HCO 3 − uptake for photosynthesis in the two algae grown in standing culture.

Using omeprazole to link the components of the post-prandial alkaline tide in the spiny dogfish,Squalus acanthias

After a meal, dogfish exhibit a metabolic alkalosis in the bloodstream and a marked excretion of basic equivalents across the gills to the external seawater. We used the H(+), K(+)-ATPase pump inhibitor omeprazole to determine whether these post-prandial alkaline tide events were linked to secretion of H(+) (accompanied by Cl(-)) in the stomach. Sharks were fitted with indwelling stomach tubes for pretreatment with omeprazole (five doses of 5 mg omeprazole per kilogram over 48 h) or comparable volumes of vehicle (saline containing 2% DMSO) and for sampling of gastric chyme. Fish were then fed an involuntary meal by means of the stomach tube consisting of minced flatfish muscle (2% of body mass) suspended in saline (4% of body mass total volume). Omeprazole pre-treatment delayed the post-prandial acidification of the gastric chyme, slowed the rise in Cl(-) concentration of the chyme and altered the patterns of other ions, indicating inhibition of H(+) and accompanying Cl(-) secretion. Omeprazole also greatly attenuated the rise in arterial pH and bicarbonate concentrations and reduced the net excretion of basic equivalents to the water by 56% over 48 h. Arterial blood CO(2) pressure (Pa(CO(2))) and plasma ions were not substantially altered. These results indicate that elevated gastric H(+) secretion (as HCl) in the digestive process is the major cause of the systemic metabolic alkalosis and the accompanying rise in base excretion across the gills that constitute the alkaline tide in the dogfish.

Endogenous ATP release inhibits electrogenic Na+ absorption and stimulates Cl− secretion in MDCK cells

Our previous studies with a line of Madin-Darby canine kidney (MDCK) cells (FL-MDCK) transfected with FLAG-labeled α, β, and γ subunits of epithelial Na+ channel (ENaC) showed that, although most of the short-circuit current (Isc) was amiloride sensitive (AS-Isc), there was also an amiloride-insensitive component (NS-Isc) due to Cl− secretion (Morris and Schafer, J Gen Physiol 120:71–85, 2002). In the present studies, we observed a progressive increase in NS-Isc and a corresponding decrease in AS-Isc during experiments. There was a significant negative correlation between AS-Isc and NS-Isc both in the presence and absence of treatment with cyclic adenosine monophosphate (cAMP). NS-Isc could be attributed to both cystic fibrosis transmembrane conductance regulator (CFTR) and a 4, 4'-diisothiocyano-2, 2'-disulfonic acid stilbene (DIDS)-sensitive Ca2+-activated Cl− channel (CaCC). Continuous perfusion of both sides of the Ussing chamber with fresh rather than recirculated bathing solutions, or addition of hexokinase (6 U/ml), prevented the time-dependent changes and increased AS-Isc by 40–60%, with a proportional decrease in NS-Isc. Addition of 100 μM adenosine triphosphate (ATP) in the presence of luminal amiloride produced a transient four-fold increase in NS-Isc that was followed by a sustained increase of 50–60% above the basal level. ATP release from the monolayers, measured by bioluminescence, was found to occur across the apical but not the basolateral membrane, and the apical release was tripled by cAMP treatment. These data show that constitutive apical ATP release, which occurs under both basal and cAMP-stimulated conditions, underlies the time-dependent rise in Cl− secretion and the proportional fall in ENaC-mediated Na+ absorption in FL-MDCK cells. Thus, endogenous ATP release can introduce a significant confounding variable in experiments with this and similar epithelial cells, and it may underlie at least some of the observed interaction between Cl− secretion and Na+ absorption.

Functional and Molecular Adaptation of Cl-/HCO3- Exchanger to Chronic Alkaline Media in RenalCells

The Cl^-/HCO₃^- exchanger (AE) is one of the mechanisms that cells have developed to adjust pH Despite its importance, the role of AE isoforms in controlling steady-state pH during alkalosis has not been widely investigated. In the present study, we have evaluated whether conditions simulating acute and chronic metabolic alkalosis affected the transport activity and protein levels of Cl-/HCO₃^- exchangers in a rat cortical collecting duct cell line (RCCD1). pH_i was monitored using the fluorescent dye BCECF in monolayers grown on permeable supports. Anion exchanger function was assessed by the response of pH_i to acute chloride removal. RT-PCR and immunoblot assays were also performed. Our results showed that RCCD1 cells express two members of the anion exchanger gene family: AE2 and AE4. Functional studies demonstrated that while in acute alkalosis pH_i became alkaline and was not regulated, after 48 h adaptation; steady-state pH_i reached a value similar to the physiological one. Chronic treated cells also resulted in a 3-fold rise in Cl^-/HCO₃^- exchange activity together with a 2.2-fold increase in AE2, but not AE4, protein abundance. We conclude that RCCD1 cells can adapt to chronic extracellular alkalosis reestablishing its steady-state pH_i and that AE2 would play a key role in cell homeostasis.

Involvement of protein tyrosine kinase in the InsP3-induced activation of Ca2+-dependent Cl- currents in cultured cells of the rat retinal pigment epithelium.

This combined study of patch-clamp and intracellular Ca2+ ([Ca2+]i) measurement was undertaken in order to identify signaling pathways that lead to activation of Ca2+-dependent Cl- channels in cultured rat retinal pigment epithelial (RPE) cells. Intracellular application of InsP3 (10 microM) led to an increase in [Ca2+]i and activation of Cl- currents. In contrast, intracellular application of Ca2+ (10 microM) only induced transient activation of Cl- currents. After full activation by InsP3, currents were insensitive to removal of extracellular Ca2+ and to the blocker of ICRAC, La3+ (10 microM), despite the fact that both maneuvers led to a decline in [Ca2+]i. The InsP3-induced rise in Cl- conductance could be prevented either by thapsigargin-induced (1 microM) depletion of intracellular Ca2+ stores or by removal of Ca2+ prior to the experiment. The effect of InsP3 could be mimicked by intracellular application of the Ca2+-chelator BAPTA (10 mm). Block of PKC (chelerythrine, 1 microM) had no effect. Inhibition of Ca2+/calmodulin kinase (KN-63, KN-92; 5 microM) reduced Cl--conductance in 50% of the cells investigated without affecting [Ca2+]i. Inhibition of protein tyrosine kinase (50 microM tyrphostin 51, 5 microM genistein, 5 microM lavendustin) reduced an increase in [Ca2+]i and Cl- conductance. In summary, elevation of [Ca]i by InsP3 leads to activation of Cl- channels involving cytosolic Ca2+ stores and Ca2+ influx from extracellular space. Tyrosine kinases are essential for the Ca2+-independent maintenance of this conductance.

Dynamics of chloride and potassium currents during the action potential in Chara studied with action potential clamp

TheCl− and K+ currents underlying the action potential (AP) in the giant alga Chara were directly recorded with the action potential clamp method. An electrically triggered action potential was recorded and repetitively replayed as command voltage to the same cell under voltage clamp. The resulting clamp current was close to zero. Only the initial rectangular current used for stimulation was approximately reproduced by the clamp circuit. Inhibition of Cl− channels with niflumic acid or ethacrynic acid and of K+ channels with Ba2+ evoked characteristic compensation currents because the amplifier had to add the selectively inhibited currents. Integration of the compensation currents revealed a mean flux through Cl− and K+ channels of 3.3 10−6 and 2.1 10−6 mole M−2 AP−1 respectively. The dynamics of CI− and K+ channel activation/inactivation were obtained by converting the relevant clamp currents to ionic permeabilities using the Goldman-Hodgkin-Katz current equation. During the AP the Cl− permeability reaches a peak 370 ms, on average, after termination of the stimulating pulse. The following inactivation proceeds 3.6 times slower than the activation. The increase in K+ permeability lags behind the rise in Cl− permeability, reaching a peak approximately 2 s after the latter.

Nature of the neutral Na(+)-Cl- coupled entry at the apical membrane of rabbit gallbladder epithelium: IV. Na+/H+, Cl-/HCO3- double exchange, hydrochlorothiazide-sensitive Na(+)-Cl- symport and Na(+)-K(+)-2Cl- cotransport are all involved.

Transepithelial fluid transport was measured gravimetrically in rabbit gallbladder (and net Na+ transport was calculated from it), at 27 degrees C, in HCO(3-)-free bathing media containing 10(-4) M acetazolamide. Whereas luminal 10(-4) M bumetanide or 10(-4) M 4-acetamido-4'-iso-thiocyanostilbene-2,2'-disulfonate (SITS) did not affect fluid absorption, 25 mM SCN- abolished it; hydrochlorothiazide (HCTZ) in the luminal medium reduced fluid absorption from 28.3 +/- 1.6 (n = 21) to 8.6 +/- 1.6 microliters cm-2 hr-1 (n = 10), i.e., to about 30%. This maximum effect was already obtained at 10(-3) M concentration; the apparent IC50 was about 2 x 10(-4) M. The residual fluid absorption, again insensitive to SITS, was completely inhibited by SCN- or bumetanide. Cl- influx at the luminal border of the epithelium, measured under the same conditions and corrected for the extracellular space and paracellular influx, proved insensitive to 10(-4) M bumetanide, but was slowly inhibited by 10(-3) M HCTZ, with maximum inhibition (about 54%) reached after a 10-min treatment; it subsequently rose again, in spite of the presence of HCTZ. However, if the epithelium, treated with HCTZ, was exposed to 10(-4) M bumetanide during the measuring time (45 sec), inhibition was completed and the subsequent rise of Cl- influx eliminated. Intracellular Cl- accumulation with respect to the predicted activity value at equilibrium decreased significantly upon exposure to 10(-3) M HCTZ, reached a minimum within 15-30 min of treatment, then rose again significantly at 60 min. Simultaneous exposure to HCTZ and bumetanide decreased the accumulation to a significantly larger extent as compared to HCTZ alone, already in 15 min, and impeded the subsequent rise. Intracellular K+ activity rose significantly within 30 min treatment with HCTZ; the increase proved bumetanide dependent. The results obtained show that Na(+)-Cl- symport, previously detected under control conditions, is the HCTZ-sensitive type; its inhibition elicits bumetanide-sensitive Na(+)-K(+)-2Cl- cotransport. Thus, the three forms of neutral Na(+)-Cl(-)-coupled transport so far evidenced in epithelia, Na+/H+, Cl-/HCO3- double exchange (in the presence of exogenous bicarbonate), HCTZ-sensitive Na(+)-Cl- symport and bumetanide-sensitive Na(+)-K(+)-2Cl- cotransport, are all present in the apical membrane of rabbit gallbladder.

Simultaneous analysis of cell Ca2+ and Ca2(+)-stimulated chloride conductance in colonic epithelial cells (HT-29).

We used perforated patch, whole-cell current recordings and video-based fluorescence ratio imaging to monitor the relation of plasma membrane ionic conductances to intracellular free Ca2+ within individual colonic epithelial cells (HT-29). The Ca2(+)-mediated agonist, neurotensin, activated K+ and Cl- conductances that showed different sensitivities to [Ca2+]i. The Cl- conductance was sensitive to increases or decreases in [Ca2+]i around the resting value of 76 +/- 32 (mean +/- SD) nM (n = 46), whereas activation of the K+ conductance required at least a 10-fold rise in [Ca2+]i. Neurotensin increased [Ca2+]i by stimulating a transient intracellular Ca2+ release, which was followed by a sustained rise in [Ca2+]i due to Ca2+ influx from the bath. The onset of the initial [Ca2+]i transient, monitored at a measurement window over the cell interior, lagged behind the rise in Cl- current during agonist stimulation. This lag was not present when the [Ca2+]i rise was due to Ca2+ entry from the bath, induced either by the agonist or by the Ca2+ ionophore ionomycin. The temporal differences in [Ca2+]i and Cl- current during the agonist-induced [Ca2+]i transient can be explained by a localized Ca2+ release from intracellular stores in the vicinity of the plasma membrane Cl- channel. Chloride currents recover toward basal values more rapidly than [Ca2+]i after the agonist-induced [Ca2+]i transient, and, during a sustained neurotensin-induced [Ca2+]i rise, Cl- currents inactivate. These findings suggest that an inhibitory pathway limits the increase in Cl- conductance that can be evoked by agonist. Because this Cl- current inhibition is not observed during a sustained [Ca2+]i rise induced by ionomycin, the inhibitory pathway may be mediated by another agonist-induced messenger, such as diacylglycerol.

Improved Patient Selection for TAH Implantation

Patient selection and optimal timing for implantation are unsettled issues in candidates for a bridge to cardiac transplantation. A prospective evaluation of a strategy based on enoximone (E) given IV, in addition to sympathomimetic drugs, permitting to buy time, and delay by hours or days the decisions, has been performed from 1985 to 1988. Thirty-four patients in cardiogenic shock with hemodynamical criteria for TAH implantation have been included: Cl was 1.8 +/- 0.2 L/min/m2 PCWP 29 +/- 7 mmHg, diuresis less than 20 ml/hr. The protocol permitted to postpone decisions of implantation in 30 cases. The 4 unresponsive patients were implanted immediately with TAH (3) or VAD (1). Three were transplanted, two successfully. For 30, time given permitted discovery of hidden contraindications to transplantation in 17 patients. In 13, indication for transplantation was confirmed and performed in 11 within 6 hrs to 8 days (survival 64%). In two, sudden deterioration led to an unsuccessful TAH implantation. Multifactorial analysis showed that a 50% rise in Cl together with a 50% drop in PCWP, a 50% drop in PVR 30 min after IV E has a high predictive value of survival. These data suggest that enoximone IV bolus given in addition to maximal sympathomimetics to patients in cardiogenic shock reduces by 88% the need for TAH or VAD. It also permits a better selection of the candidates.

THE INTELLECTUAL WORLD OF CHIAO HUNG REVISITED

AbstractChiao Hung (1540–1620) was an important figure in late Ming intellectual history. In his own day he was praised for his accomplishments in prose-writing as much as for his active interest in Neo-Confucian and Buddhist metaphysics. Since the eighteenth century, however, he has been remembered as a bibliophile and as a pioneer of “evidential research” (k'ao-cheng). He lived in an age of transition which witnesses many new developments in Chinese society, religion, and in elite as well as popular culture, but he was by no means merely a passive product of this transition. On the contrary, through his many-sided intellectual activities, he contributed significantly to the transition. On the one hand, his active participation in the movement known as “Oneness of the Three Teachings” (San-chiao ho-i) precipitated the decline, if not demise, of Ming Neo-Confucianism as a philosophical enterprise. On the other hand, his promotion of a philological approach to ancient texts paved the way for the rise of cl...

Problems in assessment of new pharmacologic agents for the heart failure patient

Modern management of congestive heart failure (CHF) employs inotropic drugs, vasodilators, and diuretics. Although pharmacologic classification of drugs is possible in animals, identification of predominant hemodynamic mechanisms in humans is more complex, because many effects of vasodilators and inotropic drugs are similar. We compared the effects of a vasodilator, prazosin, and two agents with both inotropic and vasodilatory properties, amrinone and pirbuterol, on cardiac index (Cl), mean aortic pressure, left ventricular stroke work index (LVSWI), LV filling pressure (LVFP), systemic vascular resistance, LV ejection fraction (LVEF), and myocardial O 2 consumption (MVO 2) in 34 patients with advanced CHF. We concluded that (1) a rise in Cl and LVEF, together with a fall in LVFP, does not necessarily indicate an inotropic effect; (2) both Cl and LVEF may be increased by an inotropic mechanism in advanced CHF without a rise in MVO 2; and (3) a drug-induced rise in LVSWI with stable or lower LVFP suggests an inotropic mechanism of action.