OpenPore: A low-cost, portable, battery-powered exponential decay pulse generator for electroporation.

THE difficulty in determining pulselessness via manual palpation in simulated cardiopulmonary resuscitation (CPR) has been well documented in the literature. Previous studies have suggested that trained medical personnel demonstrate a specificity of only 55% for the manual diagnoses of pulselessness.1 Other research has confirmed the poor diagnostic accuracy of manual pulse checks in a wide spectrum of test subjects—from nonmedical personnel to critical care physicians.1–4 These data, along with accumulating evidence for the importance of early, high-quality chest compression to improve outcomes from out-of-hospital cardiac arrest, have led the American Heart Association to eliminate pulse checks from their algorithm for bystander CPR.*In this context, the Advanced Cardiac Life Support algorithm for the treatment of pulseless electrical activity (PEA) arrest presents an interesting dilemma, as the very diagnosis of the PEA condition is predicated, by definition, on the finding of pulselessness. Although unnecessary chest compressions during bystander CPR are considered a relatively benign intervention, the failure to promptly diagnose the return of spontaneous circulation during in-hospital PEA Arrest may delay the institution of more targeted and appropriate care modalities. Ambiguity about the presence of spontaneous circulation during resuscitation is among many factors that contribute to the challenging task of “running a code.”Therefore, to assess possibilities for improving the detection of the return of spontaneous circulation during in-hospital resuscitation, we conducted a prospective case series (N = 8) during which handheld Doppler pulse checks were performed in parallel with standard Advanced Cardiac Life Support procedures during resuscitation of adults with putative PEA arrest or on whom electrocardiogram pads had not yet been placed in an academic tertiary care hospital. The outcomes of interest were (1) to measure the incidence of Doppler-positive-palpation-negative pulse in patients undergoing resuscitation for putative PEA arrest and (2) to measure blood pressure in discordant cases of Doppler-positive-palpation-negative putative PEA arrest.This prospective study was approved by the Yale Human Investigation Committee, including a waiver of informed consent. Investigators applied a portable Doppler (Dopplex Pocket Doppler D900 Vascular Ultrasound with 8 MHz probe; Huntleigh Healthcare Ltd. [Diagnostic Products Division], Cardiff South Glamorgan, Wales, United Kingdom) to an available femoral artery during in-hospital resuscitation attempts for putative PEA arrest or in situations of unknown cardiac rhythm before electrocardiogram lead placement. The Dopplex D900 with associated probes has been deemed by the Food and Drug Administration to be substantially equivalent to other portable ultrasound devices routinely used for blood flow monitoring. Although this technology has been in existence for several decades, the sensitivity and specificity of such devices for detecting pulsatile flow during CPR remain unknown.For inclusion in the study, a putative PEA rhythm was defined as an organized rhythm in the absence of a manual pulse, excluding ventricular tachycardia and ventricular fibrillation.† To be included in the case series, subjects also had to meet the following criteria: (1) aged more than 18 yr, (2) ongoing CPR, and (3) availability of a peripheral site for application of a Doppler probe. For included subjects, audible Doppler pulse checks occurred in addition to standard Advanced Cardiac Life Support procedures simultaneously with manual pulse checks. The site of manual pulse checks was not dictated by the research protocol. Doppler pulse checks occurred at an available femoral location that was not being used for the manual pulse check. In the event of a discordant finding of Doppler-positive-palpation-negative pulse, a repeat pulse check and blood pressure measurement were requested, with all management decisions left to the discretion of the code-runner. The cases represent a convenience sample of codes that occurred during times that a study investigator was available to respond. Codes occurred at a tertiary care hospital at which approximately 24 codes are called per month overhead, of which approximately 15% are true cardiac arrests.A total of eight subjects underwent the protocol. Discordant Doppler-positive-palpation-negative pulse checks occurred in five of eight cases for an estimated incidence of 62.5% (95% CI, 29 to 96%). In three of the five discordant cases, manual pulse checks following the finding of Doppler pulsatility resulted in a positive manual pulse check. In one of the five discordant cases, a radial artery catheter was successfully placed before repeat manual pulse check occurred, confirming pulsatile flow. In the fifth discordant case, repeat manual pulse check was negative followed by a visually confirmed pulse from a bounding carotid artery. Systolic blood pressures in the discordant group ranged from 58 to 160 mmHg with a mean of 106 mmHg. Diastolic blood pressures ranged from 30 to 100 mmHg with a mean of 56 mmHg. Four of five Doppler positive/manual negative cases survived to intensive care unit (ICU) admission, and none of the three concordant cases lacking pulsatile flow survived to ICU admission.Investigators applied the Doppler to the femoral artery site of a 45-yr-old male undergoing chest compressions for lack of pulse and before placement of electrocardiogram leads. During CPR, manual and Doppler pulse checks occurred at both radial and femoral locations without discordance (lack of pulse was found in both locations by both modalities). After placement of electrocardiogram leads, asystole was identified. Despite the continuation of CPR, there was no return of spontaneous circulation, and resuscitation efforts were eventually halted.Investigators applied the Doppler to the femoral artery site of an 82-yr-old male undergoing chest compressions for a putative PEA rhythm. At the first Doppler pulse check, there was a concordant finding of pulselessness. At the second Doppler pulse check, there was a discordant Doppler-positive-palpation-negative pulse. Compressions resumed at the direction of the code-runner without a repeat manual pulse check. At the next pulse check, a discordant Doppler-positive-palpation-negative pulse again occurred. A repeat manual pulse check was again negative at which time a member of the code team visually recognized the presence of a pulse in the form of a bounding carotid artery. A noninvasive blood pressure was measured at 160/100 mmHg. The patient survived to ICU admission.Investigators applied the Doppler to the femoral artery site of a 72-yr-old male undergoing chest compressions for a putative PEA rhythm. During CPR, manual and Doppler pulse checks found no pulse throughout the code. There was no return of spontaneous circulation, and resuscitation efforts were eventually halted.Investigators applied the Doppler to the femoral artery site of a 79-yr-old male undergoing chest compressions for a putative PEA rhythm. At the first Doppler pulse check, there was a discordant Doppler-positive-palpation-negative pulse. Compressions resumed at the direction of the code-runner without a repeat manual pulse check. At the next pulse check, a concordant Doppler-positive-palpation-positive pulse occurred. A noninvasive blood pressure was measured at 58/30 mmHg. Resuscitation efforts continued, including intermittent chest compressions based on manual pulse checks, and the patient survived to ICU admission.Investigators applied the Doppler to the femoral artery site of a 72-yr-old female undergoing chest compressions for a putative PEA rhythm that developed during a surgical procedure. At the first Doppler pulse check, there was a concordant finding of pulselessness. At the second Doppler pulse check, there was a discordant Doppler-positive-palpation-negative pulse. A radial artery catheter was placed at this time demonstrating a blood pressure of 80/50 mmHg. In the presence of an arterial line, manual and Doppler pulse checks were no longer performed. The patient eventually expired before leaving the operating room.Investigators applied the Doppler to the femoral artery site of a 35-yr-old male undergoing chest compressions for a putative PEA rhythm. During CPR, manual and Doppler pulse checks confirmed pulselessness at multiple timepoints without discordance. There was no return of spontaneous circulation, and resuscitation efforts were eventually halted.Investigators applied the Doppler to the femoral artery site of a 54-yr-old male undergoing chest compressions for a putative PEA rhythm. At the first Doppler pulse check, there was discordance between a Doppler-positive pulse and an “ambiguous” manual pulse. A repeat manual pulse check was performed, and a pulse was identified. A noninvasive blood pressure was concurrently measured at 102/54 mmHg. The patient survived to ICU admission.Investigators applied the Doppler to the femoral artery site of a 59-yr-old male undergoing chest compressions who had been shocked from pulseless ventricular tachycardia into a putative PEA rhythm. At the first Doppler pulse check, there was a discordant Doppler-positive-palpation-negative pulse. A repeat manual pulse check was performed, and a pulse was identified. A noninvasive blood pressure was measured at 127/42 mmHg. The patient survived to ICU admission.The current case series suggests that during attempts at in-hospital resuscitation, standard manual pulse checks frequently lag behind the Doppler recognition of the return of spontaneous circulation. The failure to identify a pulse on manual palpation may occur across a wide range of blood pressures, including in the presence of significant systemic hypertension.Previous studies have documented the difficulty in determining pulselessness via manual palpation. In one study, for example, investigators used a cardiopulmonary bypass model of pulselessness in a group of 206 emergency medical technician and paramedic trainees and practitioners.1 They brought subjects into a cardiac operating room and asked them to determine the presence or absence of a pulse by palpation of the carotid artery without knowing the cardiopulmonary bypass status of the patient before them. The median time to diagnosis of pulselessness among study subjects was 30 s. When asked to evaluate the group of patients who were not on cardiopulmonary bypass, 45% of study subjects made an incorrect diagnosis of pulselessness despite systolic pressures greater than 80 mmHg. Conversely, when patients were on bypass, 10% of participants diagnosed a positive carotid pulse despite the absence of pulsatile flow. When pulsatile flow was found, it took a median of 15 s to make this determination.A second group of investigators inserted aortic pressure catheters in patients undergoing CPR. They found that of 94 patients who were diagnosed clinically with electro-mechanical dissociation (since renamed PEA), 41% were found to have measurable aortic pulsations. Two of these patients were found to have systolic pressures greater than 90 mmHg.5In the current case series, the observation that three of five discordant cases were subsequently found to have a manually palpable pulse suggests that the addition of a portable Doppler to resuscitation efforts may enhance the accuracy of manual pulse checks. The portable Doppler pulse check is a practical and easily performed intervention that may help to address the difficulty of assessing pulsatility in a reliable and timely manner. However several limitations of the current case series should be highlighted. Most importantly, the effects of increasing the sensitivity of pulse checks during CPR on patient outcomes are unknown. Given the small convenience sample reported in the current case series, the benefits of Doppler pulse checks remain speculative. Among the potential benefits includes the possibility that the addition of Doppler pulse checks could prevent premature abandonment of the resuscitation effort based on an incorrectly negative manual pulse check. Supporting this notion, recent evidence has described significant differences in resuscitation times between hospitals, with more favorable outcomes associated with institutions that continue resuscitation for longer periods.6 It is also possible that of the three concordant cases, some may have had spontaneous circulation that was missed by both pulse-check modalities which, if true, could imply that Doppler pulse checks are not sufficiently sensitive to prevent premature abandonment of resuscitation efforts. Further study is needed to investigate whether Doppler pulse checks may prove a useful addition to future in-hospital resuscitation algorithms.This research was funded in part by resources from the Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut, and the National Institutes of Health, Bethesda, Maryland, Grant T32 GM086287, Principal Investigator Laura E. Niklason.The authors declare no competing interests.

: Current heavy-fuel military tactical generator sets in the 10 to 15 kw class use Diesel engines which drive low speed (3600 rpm) electrical generators. These gen sets have weight-to-power ratios that range from about 100 to 150 lbs/kw and volume-to-power ratios from about 4.0 to 5.3 ft3 per kw. In this program a preliminary design was completed for a 15 kw class dual-use, compact, light-weight portable turboelectric power gen system (designated the LTS22) with efficiency equal to the best current Army generators, a weight of approximately 100 lb (weight-to-power ratio of less than 7 lbkw) and a volume of approximately 6.2 cubic feet (volume-to-power ratio of 0.4 ft3/kw) Thus the weight and size of the LTS22 turboelectric gen set would be approximately 1/10 of today's US Army gen sets. The LTS22 generator preliminary design uses a high speed microturbine engine with an integral permanent magnet generator and electronic power controller to achieve a very light weight system. A high effectiveness, compact laminar flow (CLF) recuperator together with a low pressure-ratio turbine cycle will achieve an overall system efficiency equal to the current small diesel powered gen sets.

The Actin Cytoskeleton Has an Active Role in the Electrotransfer of Plasmid DNA in Mammalian Cells

The use of electric pulses for oculomotor muscles stimulation allows restoring the weakened contractility of muscles and achieving positive therapeutic effect. For myostimulation purposes the paper proposes to use exponential pulses with ascending and descending edges and adjustable basic frequency. The use of a microcontroller in the circuit of portable electrostimulator is relevant. It allows automating the process of affecting the muscle by impulsive complex-modulated current, not exceeding the pain threshold. The microcontroller determines the pain threshold, generates the code of stimulation pulses, not exceeding the threshold, has the function of pulse control and setting by personal computer, transfers the data on electrostimulation parameters to PC for further documentation, analysis and consultations over the Internet. The circuit of the generator of exponential-modulated pulses was developed based on the programmed microcontroller. It provides information about the pulse in the form of numeric codes and transfers it to digital-analog converter. The obtained pulse parameters correspond to the modes of electrostimulation of oculomotor muscles according to standard procedures.

The saturable reactor insulation epoxy resin is subjected to exponential decay pulse voltage under normal operating conditions. It is of great importance to study the partial discharge (PD) mechanism of epoxy resin under exponential decay pulse and sinusoidal voltages for optimal insulation design. Thus, the difference in the PD behaviours under the exponential decay pulse and sinusoidal voltages is revealed in this study for the first time, and the PD characteristics of the two types of voltages are compared and analysed at 25 and 110°C. Compared to the results for sinusoidal voltage, a higher amplitude, lower repetitive PD inception voltage peak (RPDIV) and fewer PDs are obtained under an exponential decay pulse voltage. Additionally, for the same type of voltage, the RPDIV is lower, the PD magnitude is higher and the number of PDs is smaller at 110°C than those at 25°C. The experimental results can provide a new reference for the insulation redesign of a saturable reactor under an exponential decay pulse voltage.

In this article, three different types of pulse generators based on multimodule boost converter ringing circuit are presented, namely, interleaved, stacked, and interleaved–stacked with full design and operational concept. The interleaved version is advantageous in generating a burst of pulses with moderate voltage magnitude, where the used modules are fed from a common dc source. On the other hand, the stacked multimodule version can be used to generate high-voltage pulsed output from synchronized modules with a moderate voltage rating. This can be done by feeding the modules from isolated dc sources while connecting their outputs in series. Finally, the interleaved–stacked version can be used for generating a burst of pulses with high-voltage magnitude. The presented pulse generators are valid for resistive loads with exponential decay pulses. The suggested pulse generators are simple and require semiconductor devices with moderate voltage ratings. For given pulse specifications, a detailed design for the passive components of each version is presented in this article. The simulation and experimental results are used to validate the suggested topologies.

The high voltage load applications need very compact generators for the production of fast rising high voltage pulses and are invited in many applications including plasma soft X-ray, ion beam, PEF technology and microwave generators. From the right beginning several technologies have been introduced, Pulse Forming Networks, up to Marx generators. This paper also presents such type of square pulse generator based on power semiconductor device which simplifies the size of the conventional pulse generators. The high electric field intensity square pulses varying in magnitudes in the range of kilovolts with ms to µs pulse widths have been successfully used in many research fields. The advancements in power semiconductor devices, such as power MOSFETs, IGBTs are becoming most suitable for high switching speed high voltage pulse generators. These semiconductor devices are more reliable to control high voltages and currents when implemented in typical circuits. The voltage and current capabilities are increased by connecting the power switches in series and parallel respectively which need aided circuit for protection, equal voltage distributions. This paper presents the design and implementation of such a compact, portable high voltage µs pulse generator based on single power MOSFETs thus avoiding auxiliary circuits. A single CoolMOSTM RF Power MOSFET IXZR08N120B is selected as main switch in this work to produce the high voltage square pulses and is triggered using the suitable high-speed driver DEIC420 with low jitter at higher frequencies. The designed high voltage pulse generator which has variable pulse widths ranging from 2µs to 200μs with a variable pulse magnitude of 1kV is implemented in our laboratory. Keywords: CoolMOSTM Device, High Speed Driver DEIC420, Power Switch, Pulse Generator, RF Power MOSFET, Schmitt Trigger

Diaphanous-related formins (DRFs) mediate GTPase-triggered actin rearrangements to regulate central cellular processes, such as cell motility and cytokinesis. The DRF FHOD1 interacts with the Rho-GTPase Rac1 and mediates formation of actin stress fibers in its deregulated form; the physiologically relevant activities and molecular mechanisms of endogenous FHOD1, however, are still unknown. Here we report that FHOD1 physically associates via the N-terminal part of its FH2 domain with the central domain of ROCK1. Although FHOD1 does not affect the kinase activity of ROCK1, the DRF is an efficient substrate for phosphorylation by ROCK1. Co-expression of FHOD1 and ROCK1 results in the generation of nonapoptotic plasma membrane (PM) blebs, to which the DRF is efficiently recruited. Blebbing induced by FHOD1 and ROCK1 depends on F-actin integrity, the Rho-ROCK cascade, and Src activity and is reminiscent of the recently described PM blebs triggered by expression of Src homology 4 (SH4) domain PM targeting signals. Consistently, endogenous FHOD1 is required in SH4 domain expressing cells for efficient PM blebbing and rounded cell morphology in two-dimensional cultures or three-dimensional matrices, respectively. Efficient association of FHOD1 with ROCK1, as well as recruitment of the DRF to blebs, depends on Src activity, suggesting that the functional interaction between both proteins is regulated by Src. These results define a role for endogenous FHOD1 in SH4 domain-induced blebbing and suggest that its activity is regulated by ROCK1 in a Src-dependent manner.

During the decades, the development of high power semiconductor switches and magnetic cores have allowed us manufacturing pulsed power sources with high energy transfer efficiency. As the results, the pulsed discharge has been recognized as one of the promised non-thermal plasma techniques for practical use. However, the energy transfer efficiency of pulsed discharge system is approximately 30% although in the best condition. In the practical process of its applications, higher energy efficiency is required. In this study, the reason why the conventional pulsed discharge system had stayed in low energy transfer efficiency was described. Furthermore, performance of the nanoseconds pulsed (ns pulse generator) was presented with higher energy transfer efficiency and its applications of exhaust gas treatment experiments. As the results, the energy transfer efficiency of up to 62 % was achieved by improving the impedance matching between ns pulse generator and discharge reactor. In the exhaust gas treatment experiment, NO removal ratio of 100 % (initial NO concentration - 200 ppm) and improvement of NO removal energy efficiency were obtained. (4 pages)

Transformer-less Grid-Connected High-Voltage Marx Pulse Generator with Unity Power Factor for Domestic Drinking Water Disinfection

Generateur d'impulsions nanoseconde et circuit de mise en forme a transistors avalanche

Summary form only given. The conventional methods such as SCR method, Electron Beam method and Lime-gypsum method could not treat exhaust gases completely. In addition, the energy efficiency and the cost in the conventional ways are still negative situation. In recent years, the pollution control techniques using electric discharge plasmas which could attract attention as the low cost and high energy efficient exhaust gas treatment method, have been widely studied. In our laboratory, pulsed streamer discharge plasmas which are one of the non-thermal plasmas have been used to treat exhaust gases. Since a pulse width of applied voltage has a strong influence on the energy efficiency of the removal of pollutants, the development of a short pulse generator is of paramount importance for practical applications. In this work, ns pulse generator which can output the 5ns pulsed voltage is developed. Furthermore, the NO removal experiment is conducted using the ns pulse generator. As the results, the ns pulsed discharge has an advantage in energy efficiency for NO removal in comparison with sub-mus pulsed discharge. As the characteristics of NO removal using the ns pulsed streamer discharge, the polarity of and the amplitude of applied voltage to the reactor have significant influences on the improvement of energy efficiency of NO removal. On the other hands, it is clear that the longer length of and the smaller diameter of the coaxial discharge reactor give the higher energy efficiency. The maximum energy efficiency of NO removal by ns pulsed streamer discharges reaches 1.5 mol/kWh at 60% of NO removal ratio.

Activation of TRPC3 channels is concurrent with inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R)-mediated intracellular Ca(2+) release and associated with phosphatidylinositol 4,5-bisphosphate hydrolysis and recruitment to the plasma membrane. Here we report that interaction of TRPC3 with receptor for activated C-kinase-1 (RACK1) not only determines plasma membrane localization of the channel but also the interaction of IP(3)R with RACK1 and IP(3)-dependent intracellular Ca(2+) release. We show that TRPC3 interacts with RACK1 via N-terminal residues Glu-232, Asp-233, Glu-240, and Glu-244. Carbachol (CCh) stimulation of HEK293 cells expressing wild type TRPC3 induced recruitment of a ternary TRPC3-RACK1-IP(3)R complex and increased surface expression of TRPC3 and Ca(2+) entry. Mutation of the putative RACK1 binding sequence in TRPC3 disrupted plasma membrane localization of the channel. CCh-stimulated recruitment of TRPC3-RACK1-IP(3)R complex as well as increased surface expression of TRPC3 and receptor-operated Ca(2+) entry were also attenuated. Importantly, CCh-induced intracellular Ca(2+) release was significantly reduced as was RACK1-IP(3)R association without any change in thapsigargin-stimulated Ca(2+) release and entry. Knockdown of endogenous TRPC3 also decreased RACK1-IP(3)R association and decreased CCh-stimulated Ca(2+) entry. Furthermore, an oscillatory pattern of CCh-stimulated intracellular Ca(2+) release was seen in these cells compared with the more sustained pattern seen in control cells. Similar oscillatory pattern of Ca(2+) release was seen after CCh stimulation of cells expressing the TRPC3 mutant. Together these data demonstrate a novel role for TRPC3 in regulation of IP(3)R function. We suggest TRPC3 controls agonist-stimulated intracellular Ca(2+) release by mediating interaction between IP(3)R and RACK1.

Summary form given only. Pulsed power technology has been used in many applications such as control of NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> from exhaust gases, treatment of dioxins, removal of volatile organic compounds, generation of ozone and excitation of excimer laser. Since pulse duration of applied voltage to discharge reactor has a strong influence on energy efficiency of pollutants removal, the development of short pulse generator is paramount important for practical applications. The discharge observation of the short duration pulse voltage is an essential aspect for understanding plasma physics of this new field. In the present work, the characteristics of the developed nano-seconds (ns) pulse generator, which has the pulse duration of 5 ns, and the observation results of nano-second (ns) pulsed streamer discharges in atmospheric air are presented. The developed ns pulse generator consists of a high pressure spark gap as a lower inductance self-closing switch, a triaxial Blumlein line as a pulse forming line, a coaxial energy transmission line as a connection between the Blumlein and a load, and a pulse charging source. The triaxial Blumlein line is filled up with transformer oil as insulation and dielectric medium. The ns pulse generator outputs the positive voltage, having 2 ns of rise time and 5 ns of pulse duration. The maximum output voltage reaches up to 100 kV. The propagations of the positive and the negative ns pulsed streamer discharges in a coaxial electrode were observed using a high speed gated ICCD camera and a high dynamic range streak camera. During the both polarities of ns pulsed streamer discharges, the primary and the secondary streamers propagated from inner wire to outer cylinder electrodes. This phenomenon has good agreement to the previous works which are observed in the cases of sub-frac14s pulsed streamer discharges. However, the propagation velocity of the primary streamers in the present work is approximately 6 times faster than the previous one. This is because that the velocity of primary streamers dependent on applied voltage to electrode and ns pulse generator is able to apply the higher voltage to electrode than sub-frac14s pulse generator.

Phosphorylation of serine and threonine residues in the carboxyl-terminal region of many G-protein-coupled receptors directs the rapid uncoupling from signal transduction pathways. In Chinese hamster ovary cells, we have stably expressed a truncated mutant of the angiotensin II (AT1A) receptor devoid of the carboxyl-terminal 45 amino acids, encompassing 13 serine/threonine residues. One clone, designated TL314 to indicate truncation after leucine 314, expressed a single class of angiotensin II receptors with a dissociation constant of 1.08 nM and a receptor density of 560 fmol/mg of protein (approximately 75,000 receptors/cell). A nonhydrolyzable analog of GTP accelerated the angiotensin II-induced dissociation of [125I]angiotensin II from TL314 plasma membranes 3.6-fold, indicating G-protein coupling. In TL314 cells, angiotensin II stimulated the release of intracellular calcium and the induction of mitogen-activated protein kinase activity, the level of which were comparable with the full-length AT1A receptor. The AII-stimulated calcium response was rapidly desensitized in both full-length and truncated AT1A receptors. Interestingly, angiotensin II-induced endocytosis of the truncated receptor was almost completely inhibited, suggesting that a recognition motif within the carboxyl-terminal 45 amino acids of the AT1A receptor promotes sequestration. Thus, truncation of the AT1A receptor after leucine 314 inhibits agonist-induced internalization without affecting the capacity of the expressed protein to adopt the correct conformation necessary for high affinity binding of angiotensin II, coupling to G-proteins, and activation of signal transduction pathways. The rapid desensitization and refractoriness of the angiotensin II-induced calcium transient in the TL314 cell line, in which putative carboxyl-terminal phosphorylation sites are absent, suggests that the mechanism of AT1A receptor desensitization differs from that of other prototypical G-protein-coupled receptors.