The Japanese Epidemiologic Study for Perioperative Anaphylaxis, a prospective nationwide study: clinical signs, severity, and therapeutic agents.

BACKGROUND: Diagnosis of perioperative anaphylaxis is difficult because of its non-specific and variable signs and symptoms. Therapeutic agents used to treat anaphylaxis and anaesthesiologist responses also vary depending on the case, which might affect outcomes; however, only a few studies have focused on these factors. METHODS: This prospective study of perioperative anaphylaxis, a part of the Japanese Epidemiologic Study for Perioperative Anaphylaxis, investigated the clinical signs, its severity, therapeutic drugs, epinephrine administration, and anaesthesiologist responses in cases of perioperative anaphylaxis to assess trends and variability. Shock index was used to assess severity of cardiovascular collapse. RESULTS: In 43 patients analysed in this study, cardiovascular signs (88.4%) were the most frequent, followed by skin (81.4%) and respiratory signs (60.5%). The presence of signs increased during the clinical course. The median time from the first signs to diagnosis of anaphylaxis was 10 (5.0-17.8) min. The rates of epinephrine use were 30.2% (unused), 48.8% (i.v.), and 20.9% (i.m.). The median time from diagnosis of anaphylaxis to epinephrine administration was 7 (inter-quartile range: 1.5-8.0) min. Antihistamines and corticosteroids were each used in 69.8% of cases. The worst shock index was higher in patients who received i.v. epinephrine (2.77 [0.90] mean [standard deviation]) than in both no epinephrine use cases (1.35 [0.41]) and i.m. epinephrine cases (1.89 [0.77] (P<0.001]). CONCLUSIONS: The clinical signs and treatments of perioperative anaphylaxis are variable, and the choice regarding epinephrine administration is based on symptom severity. CLINICAL TRIAL REGISTRATION: UMIN000035350.

Dexmedetomidine improves excessive extracellular glutamate-induced synaptic depression (BRAINRES-D-21-00941).

We investigated the effects of dexmedetomidine, a selective α2-adrenergic agonist and a sedative, on excessive glutamate-induced depressions of central excitatory synaptic transmissions in vitro. From the CA1 in rat hippocampal slices, orthodromically elicited population spikes (PSs) and field excitatory postsynaptic potentials (fEPSPs) at 0.1 Hz were simultaneously recorded. ANOVA was used for statistics, and p < 0.05 was accepted as significant. Glutamate (10 mM for 10 min) completely depressed PSs and fEPSPs, which were partially recovered by the following washout for 40 min (57.4 ± 10.2% and 59.9 ± 9.8% of the control, respectively, p < 0.01, n = 6). The recoveries in PSs and fEPSPs were improved by pre-treatment and simultaneous treatment with dexmedetomidine (p < 0.01, n = 6) but were not altered by post-treatment. Dexmedetomidine alone did not alter PSs and fEPSPs. Simultaneous treatment with isoproterenol or dobutamine exacerbated the recoveries in PSs and fEPSPs (p < 0.01, n = 6), but simultaneous treatment with salbutamol, propranolol, phenylephrine or phentramine did not influence the recoveries. Simultaneous treatment with AP5 improved the recoveries in PSs and fEPSPs that were depressed by glutamate alone and by glutamate with dexmedetomidine, isoproterenol or dobutamine (p < 0.01, n = 6). Excessive glutamate depresses glutamatergic excitatory synaptic transmissions by mainly mediating NMDA receptors, and the depressed transmissions are improved by α2-adrenoceptor stimulation but are exacerbated by ß1-adrenoceptor stimulation. Dexmedetomidine has a protective effect on neuronal dysfunctions induced by excessive glutamate, which is one of the main mechanisms of the secondary damage in the central nervous system.

Bilateral phrenic nerve block as an effective means of controlling inspiratory efforts in a COVID-19 patient.

Bilateral continuous phrenic nerve block effectively regulates refractory persistent, strong inspiratory effort in a patient with coronavirus disease (COVID-19). A 73-year-old man with acute respiratory distress syndrome (ARDS) due to COVID-19 was admitted to the intensive care unit (ICU). Use of neuromuscular blocking agents (NMBAs) was stopped due to uncontrollable strong inspiratory efforts and worsened lung injury. We performed bilateral continuous phrenic nerve block, which suppressed inspiratory efforts, resulting in lung injury improvement. A bilateral continuous phrenic nerve block is a viable alternative to control refractory strong inspiratory effort leading to lung injury in cases with prolonged NMBA use.

Generic rocuronium reduces withdrawal movements compared to original rocuronium under target-controlled infusion induction with propofol.

PURPOSE: Rocuronium-induced injection pain often causes withdrawal movements leading to accidental disruption of indwelling needles. Generic rocuronium (Maruishi Pharmaceutical Co., Ltd, Osaka, Japan) with a novel solution has been reported to reduce the injection pain compared to original rocuronium [Esmeron® (Eslax®), MSD Co. Ltd, Tokyo, Japan], however, no reports have compared the injection pain under sedation with propofol, the most frequently used general anesthetic. This study was carried out to compare the injection pain caused by generic rocuronium and that caused by original rocuronium in patients anesthetized by propofol with a target-controlled infusion system. METHODS: Forty patients were randomly assigned to two groups in this single-center, prospective, randomized, double-blind study. One group was administered generic rocuronium after sedation with propofol with a target-controlled infusion system. The other group was administered original rocuronium after anesthesia with propofol. Patient's withdrawal movements were assessed with the scale. The primary outcome was the total incidence of movement after administration of rocuronium. Secondary outcome was the incidence of moderate or severe movement after administration of rocuronium. RESULTS: The total incidence of movement after administration of generic rocuronium (11%) was significantly lower than that after the administration of original rocuronium (79%) (p < 0.01). The incidence of moderate or severe movement after administration of generic rocuronium (0%) was significantly lower than that after the administration of original rocuronium (53%) (p < 0.01). CONCLUSION: Generic rocuronium was considered more suitable than the original rocuronium for induction of anesthesia by propofol performed with a target-controlled infusion system.

Eco-friendly green synthesis of clove buds extract functionalized silver nanoparticles and evaluation of antibacterial and antidiatom activity.

Biological fouling has caused a lot of concern in marine industries due to the attachment of microorganisms on marine surfaces. Silver nanoparticles (AgNPs) have a great potential to inhibit and hold strong toxicity against microorganisms on artificial surfaces immersed in seawater. In this study, AgNPs are synthesized using extract of clove buds (CE) plant as a reducing and stabilizing agent by biological synthesis method. The obtained CE-AgNPs product was characterized by using different techniques. Ultraviolet-visible spectroscopy (UV-Vis) results confirmed the formation of CE-AgNPs with its surface plasmon resonance peak range. Fourier-transform infrared spectroscopy (FTIR) study showed the formation of functional groups responsible for the reduction of Ag+ into Ago. X-Ray Diffraction (XRD) results revealed face-centered cubic (fcc) silver crystals having four different diffraction peaks at 38.08, 44.21, 64.42 and 77.32 with corresponding lattice plane value recorded at (111), (200), (220) and (311), respectively. Structural characterization using scanning electron microscopy equipped with energy dispersive X-Ray Analyzer (SEM-EDX), Transmission electron microscopy (TEM) and atomic force microscopy (AFM) also confirmed the successful formation of CE-AgNPs with fcc structure. The histogram of particle size distribution through TEM image showed an average size of 9.42 nm of the synthesized product. Finally, the antibacterial and antidiatom activity of the synthesized product was analyzed. The CE-AgNPs synthesized using CE possesses good inhibitory activity against the marine bacterium community and Nitzschia closterium diatom. These results indicate that CE-AgNPs can be used as a novel material for antibacterial and antidiatoms means to inhibit the biofouling on marine surfaces.

Epidural analgesia for the treatment of colic attack with retrocaval ureter in late pregnancy complicated with marginal placenta previa: a case report.

BACKGROUND: Retrocaval ureter was diagnosed in a woman complaining of ureteric pain in the last trimester of pregnancy. We describe the rationale behind the administration of epidural analgesia for her colic attack. CASE PRESENTATION: A 41-year-old pregnant woman was hospitalized with a diagnosis of a marginal placenta previa at 34 weeks and 5 days of pregnancy. Her right ureter encircled the dorsal aspect of the inferior vena cava (IVC) and was compressed by a growing fetus, causing hydronephrosis. Her right lower back pain was exacerbated every day, till an epidural catheter was inserted. Her estimated glomerular filtration rate (eGFR) and hematocrit worsened, and an elective cesarean section was performed. CONCLUSION: Epidural analgesia only provided pain relief for a few days. When a pregnant woman presents with a retrocaval ureter and severe pain, short-term epidural analgesia should be considered after evaluating the complex medical condition and size of the fetus.

Formation of the chaperonin complex studied by 2D NMR spectroscopy.

We studied the interaction between GroES and a single-ring mutant (SR1) of GroEL by the NMR titration of 15N-labeled GroES with SR1 at three different temperatures (20, 25 and 30°C) in the presence of 3 mM ADP in 100 mM KCl and 10 mM MgCl2 at pH 7.5. We used SR1 instead of wild-type double-ring GroEL to precisely control the stoichiometry of the GroES binding to be 1:1 ([SR1]:[GroES]). Native heptameric GroES was very flexible, showing well resolved cross peaks of the residues in a mobile loop segment (residue 17-34) and at the top of a roof hairpin (Asn51) in the heteronuclear single quantum coherence spectra. The binding of SR1 to GroES caused the cross peaks to disappear simultaneously, and hence it occurred in a single-step cooperative manner with significant immobilization of the whole GroES structure. The binding was thus entropic with a positive entropy change (219 J/mol/K) and a positive enthalpy change (35 kJ/mol), and the binding constant was estimated at 1.9×105 M-1 at 25°C. The NMR titration in 3 mM ATP also indicated that the binding constant between GroES and SR1 increased more than tenfold as compared with the binding constant in 3 mM ADP. These results will be discussed in relation to the structure and mechanisms of the chaperonin GroEL/GroES complex.

Three cases of implantation of a SureScan® system and MRI for investigating causes of pain.

We report three cases of implantation of the SureScan® system and magnetic resonance imaging (MRI) for investigating causes of pain. Although there were metal-induced artifacts on the MR images of 2 patients, the artifacts did not affect the images of structures that needed to be assessed to make the diagnosis. The SureScan® system enabled patients implanted with spinal cord stimulation devices to undergo MRI.

Fabrication of ZIF-8@SiO2 Micro/Nano Hierarchical Superhydrophobic Surface on AZ31 Magnesium Alloy with Impressive Corrosion Resistance and Abrasion Resistance.

Superhydrophobic coatings are highly promising for protecting material surfaces and for wide applications. In this study, superhydrophobic composites, comprising a rhombic-dodecahedral zeolitic imidazolate framework (ZIF-8@SiO2), have been manufactured onto AZ31 magnesium alloy via chemical etching and dip-coating methods to enhance stability and corrosion resistance. Herein, we report on a simple strategy to modify hydrophobic hexadecyltrimethoxysilan (HDTMS) on ZIF-8@SiO2 to significantly improve the property of repelling water. We show that various liquids can be stable on its surface and maintain a contact angle higher than 150°. The morphologies and chemical composition were characterized by means of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FI-IR). In addition, the anticorrosion and antiattrition properties of the film were assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization and HT, respectively. Such a coating shows promising potential as a material for large-scale fabrication.

A case of a warfarinized renal cancer patient monitored for prothrombin time-international normalized ratio during methadone introduction.

BACKGROUND: Warfarin, a widely used anticoagulant, interacts with various agents used in palliative care, such as oxycodone, morphine, acetaminophen, and non-steroidal anti-inflammatory drugs (NSAIDs); however, there are no reports of its interaction with methadone. We report a case of a patient receiving warfarin when methadone was introduced for pain control with monitoring of the prothrombin time-international normalized ratio (PT-INR) and deduced the pharmacological background. CASE PRESENTATION: A 60-year-old male was emergently admitted to our university hospital for the sudden onset of severe back pain. Abdominal CT imaging revealed that the vertebral body of the ninth thoracic vertebra was occupied by bone metastasis and crushed, which caused his back pain. He received warfarin 3.5 mg/day for atrial fibrillation and tapentadol 100 mg p.o. daily for pain relief. The prothrombin time-international normalized ratio (PT-INR) was maintained at >2.2. The patient's history included diabetes mellitus and hypertension, but his laboratory test was unremarkable with the exception that his eGFR was 34 ml/min.Initially, a fentanyl dermal patch was used instead of tapentadol to avoid interactions with warfarin. We started concomitant administration of oxycodone and 2.4 g/day of acetaminophen while monitoring the PT-INR because acetaminophen increased the PT-INR to 2.93. A continuous intravenous infusion of oxycodone was introduced, in increments of the dose, resulting in an increase of the PT-INR to 3.41, which is required to reduce the dose of warfarin to 1.5 mg. Because of the lack of effective pain relief, methadone was introduced and the dose was gradually increased. The PT-INR was not changed and the dose of warfarin was not changed. An infusion of oxycodone and oral methadone was used to allow the patient to walk in his room, and he was later transferred to the palliative hospital. CONCLUSIONS: In an oral warfarinized patient, methadone seemed to undergo different metabolism than oxycodone. When warfarin and methadone are used together, we have to consider their interaction by comparing the competitive inhibition of CYP2C9 to the induction of CYP3A4 by methadone, because CYP3A4 metabolize various drugs including oxycodone.

Severity of Myasthenia Gravis Influences the Relationship between Train-of-four Ratio and Twitch Tension and Run-down of Rat Endplate Potentials.

BACKGROUND: Train-of-four ratio (TOFR) is often used to evaluate muscle relaxation caused by neuromuscular-blocking agents (NMBAs). However, it is unknown whether TOFR reliably correlates with the first twitch tension (T1) in patients with myasthenia gravis (MG). By using rat models of experimental autoimmune MG (EAMG), the authors verified the hypothesis that the severity of MG influences the relationship between TOFR and T1. METHODS: EAMG rats were divided into sham, moderate MG, and severe MG groups. Isometric twitch tension of the hemidiaphragm was elicited by phrenic nerve stimulation with and without use of the NMBA rocuronium to measure TOFR and T1, and run-down of endplate potentials was estimated in the three groups. Changes around the neuromuscular junction in EAMG rats were investigated by observation of electron micrographs. RESULTS: With similar attenuation of T1, TOFR was significantly (n = 6) different among the three groups in the presence of 50% inhibitory concentrations of rocuronium (IC50). Run-down in the sham group was significantly (n = 8) greater with exposure to IC50, whereas that in the severe MG group was statistically insignificant. Width of the primary synaptic cleft in the severe MG group was significantly (n = 80) greater than that in the other groups. CONCLUSIONS: Severity of MG influences the relationship between TOFR and T1, together with changes in run-down of endplate potentials and those around the neuromuscular junction in rats. TOFR may, therefore, not be an accurate indicator of recovery from NMBAs in MG patients.

Regulation of Proteasomal Degradation by Modulating Proteasomal Initiation Regions.

Methods for regulating the concentrations of specific cellular proteins are valuable tools for biomedical studies. Artificial regulation of protein degradation by the proteasome is receiving increasing attention. Efficient proteasomal protein degradation requires a degron with two components: a ubiquitin tag that is recognized by the proteasome and a disordered region at which the proteasome engages the substrate and initiates degradation. Here we show that degradation rates can be regulated by modulating the disordered initiation region by the binding of modifier molecules, in vitro and in vivo. These results suggest that artificial modulation of proteasome initiation is a versatile method for conditionally inhibiting the proteasomal degradation of specific proteins.

Differential axillary nerve block for hand or forearm soft-tissue surgery.

PURPOSE: This study determined the effective concentration of ropivacaine required to produce the type of differential block known as sensory block with mobilization, for adequate analgesia after forearm or hand soft tissue surgery by axillary brachial plexus block. METHODS: Forty-four patients were enrolled, and ultrasound-guided axillary nerve block with nerve stimulation was achieved using 16 mL of ropivacaine in total. Postoperative analgesia and sensory/motor function, side effects, the use of rescue analgesics, and the patient satisfaction score were evaluated 24 h after surgery. The effective concentration of nerve block was calculated by probit analysis. RESULTS: Eighteen patients achieved differential block and were sufficiently satisfied with the block, which was significantly better than the patient satisfaction obtained with incomplete differential block. The maximum effective concentration of 6 mL of ropivacaine needed for differential block was calculated as 0.1285 %, which meant that 71 % of the patients experienced both sensory block and maintenance of motor function. CONCLUSION: This analysis showed that 16 ml of 0.1285 % ropivacaine is suitable for achieving differential block in ultrasound-guided axillary nerve block for hand and forearm surgery.

Blockers of adenosine A1, but not muscarinic acetylcholine, receptors improve excessive extracellular glutamate-induced synaptic depression.

We investigated adenosinergic and cholinergic effects on excessive glutamate-induced depressions of central excitatory synaptic transmissions in vitro. From the CA1 region in rat hippocampal slices, orthodromically elicited population spikes (PSs) and field excitatory postsynaptic potentials (fEPSPs) at 0.1Hz were simultaneously recorded. ANOVA was used for statistics, and p<0.05 was accepted as significant. Glutamate (10mM for 10min) completely depressed PSs and fEPSPs, which were partially recovered by the following washout for 40min (67.5±15.7% and 65.4±13.9% of the control, respectively, p<0.01, n=12). The recoveries in PSs and fEPSPs were exacerbated by edrophonium and carbamoylcholine but improved by non- and A1-selective adenosine receptor antagonists (p<0.01, n=6). The recovery in PSs, not that in fEPSPs, was exacerbated by adenosine, adenosine A1-receptor agonist and A2a-receptor antagonist (p<0.01, n=6). The effects of edrophonium were blocked by non-, M2- and M4-selective muscarinic acetylcholine receptor antagonists (p<0.01, n=6). Excessive glutamate depresses glutamatergic excitatory synaptic transmissions, which are exacerbated by muscarinic acetylcholine receptor stimulation but improved by adenosine A1 receptor block. Somatic excitability is impaired by excessive glutamate with adenosine A1 receptor stimulation.

Pralidoxime inhibits paraoxon-induced depression of rocuronium-neuromuscular block in a time-dependent fashion.

OBJECTIVE: The composite effects of organophosphorus (OP)-cholinesterase (ChE) inhibitors and oximes on the actions of nondepolarizing neuromuscular blockers in acute OP-ChE inhibitor intoxication have not been evaluated in detail. We investigated the effects of paraoxon (Pox) (an OP-ChE inhibitor) and pralidoxime (PAM) (an oxime) on the nondepolarizing neuromuscular blocking action of rocuronium. METHODS: Isometric twitch tensions of rat left phrenic nerve-hemidiaphragm preparations elicited by indirect (phrenic nerve) supramaximal stimulation at 0.1 Hz were evaluated. Analysis of variance with post hoc testing was used for statistical comparison, and P < .05 was accepted as significant. RESULTS: Rocuronium reduced the indirectly elicited twitch tensions in normal (50% inhibitory concentration [IC(50)], 9.84 [9.64-10.04] µM, mean [95% confidence interval]) and all pretreated diaphragms (P < .01, n = 6) in a concentration-dependent fashion. Paraoxon caused a rightward shift in the rocuronium concentration-twitch tension curve (IC(50), 15.48 [15.24-15.72] µM). The rightward shift was completely inhibited by previous copretreatment (IC(50), 9.98 [9.77-10.20] µM) and partially inhibited by simultaneous copretreatment (IC(50), 11.68 [11.45-11.91] µM) with PAM but was not inhibited by subsequent copretreatment (IC(50), 13.69 [13.39-13.99] µM) with PAM (P < .01, n = 6). Atropine did not influence the rightward shift (P < .01, n = 6). DISCUSSION: Paraoxon depressed rocuronium-induced neuromuscular block by inhibiting ChEs, and the action of Pox was inhibited by PAM. Pralidoxime acts more intensely when applied earlier. The time-dependent effect of PAM indicates that the preceding presence of PAM in proximity to ChEs before Pox is necessary for definite suppression of the Pox-induced ChE inhibition.

Adaptation of a hyperthermophilic group II chaperonin to relatively moderate temperatures.

Group II chaperonins exist in archaea and the eukaryotic cytosol, and mediate protein folding in an ATP-dependent manner. We have been studying the reaction mechanism of group II chaperonins using alpha chaperonin, the recombinant chaperonin alpha subunit homo-oligomer from a hyperthermophilic archaeon, Thermococcus sp. strain KS-1 (T. KS-1). Although the high stability and activity of T. KS-1 alpha chaperonin provided advantages for our study, its high thermophilicity caused the difficulty in using various analytical methods. To resolve this problem, we tried to adapt T. KS-1 alpha chaperonin to moderate temperatures by mutations. The comparison of amino acid sequences between 26 thermophilic and 17 mesophilic chaperonins showed that three amino acid replacements are likely responsible for the difference of their optimal temperatures. We introduced three single mutations and also their double combinations into T. KS-1 alpha chaperonin. Among them, K323R single mutant exhibited the improvements of the folding activity and the ATP-dependent conformational change ability at lower temperatures, such as 50 degrees C and 40 degrees C. Since K323 may secure helix 12 in the closed conformation by interacting with D198, the replacement of Lys to Arg likely induced the higher mobility of the built-in lid, resulting in the higher activity at relatively low temperatures.

Usefulness of Endoflex endotracheal tube for oral and nasal tracheal intubations.

BACKGROUND AND OBJECTIVES: We investigated the usefulness of an Endoflex tracheal tube, the tip of which can be bent forward by pulling on a wire held in the hand, for oral and nasal endotracheal intubations without a stylet, in comparison with tracheal intubation using a conventional endotracheal tube and a stylet/Magill forceps. METHODS: The study participants comprised 40 patients for oral intubation and 20 patients for nasal intubation. Each group was then divided into control and Endoflex subgroups. In the oral intubation study, controls were intubated using a standard Macintosh-type laryngoscope with a conventional endotracheal tube with adjuvant use of a stylet, whereas the Endoflex group was intubated using a Macintosh-type laryngoscope with an Endoflex tube. In the nasal intubation study, controls were intubated by a standard Macintosh-type laryngoscope with an endotracheal tube for nasal intubation. Under direct vision, Magill forceps were used to guide the tip of the endotracheal tube into the glottis. Patients in the Endoflex group were intubated using a Macintosh-type laryngoscope with an Endoflex tube. RESULTS: Although haemodynamic changes during tracheal intubation did not differ between the groups, the duration of intubation was significantly shortened in the Endoflex groups in both studies. CONCLUSION: The Endoflex endotracheal tube represents a beneficial tool for smooth oral and nasal intubation without requiring assistance or adjuvant equipment.

Sequential action of ATP-dependent subunit conformational change and interaction between helical protrusions in the closure of the built-in lid of group II chaperonins.

ATP drives the conformational change of the group II chaperonin from the open lid substrate-binding conformation to the closed lid conformation to encapsulate an unfolded protein in the central cavity. The detailed mechanism of this conformational change remains unknown. To elucidate the intra-ring cooperative action of subunits for the conformational change, we constructed Thermococcus chaperonin complexes containing mutant subunits in an ordered manner and examined their folding and conformational change abilities. Chaperonin complexes containing wild-type subunits and mutant subunits with impaired ATP-dependent conformational change ability or ATP hydrolysis activity, one by one, exhibited high protein refolding ability. The effects of the mutant subunits correlate with the number and order in the ring. In contrast, the use of a mutant lacking helical protrusion severely affected the function. Interestingly, these mutant chaperonin complexes also exhibited ATP-dependent conformational changes as demonstrated by small angle x-ray scattering, protease digestion, and changes in fluorescence of the fluorophore attached to the tip of the helical protrusion. However, their conformational change is likely to be transient. They captured denatured proteins even in the presence of ATP, whereas addition of ATP impaired the ability of the wild-type chaperonin to protect citrate synthase from thermal aggregation. These results suggest that ATP binding/hydrolysis causes the independent conformational change of the subunit, and further conformational change for the complete closure of the lid is induced and stabilized by the interaction between helical protrusions.

Asymmetry of the GroEL-GroES complex under physiological conditions as revealed by small-angle x-ray scattering.

Despite the well-known functional importance of GroEL-GroES complex formation during the chaperonin cycle, the stoichiometry of the complex has not been clarified. The complex can occur either as an asymmetric 1:1 GroEL-GroES complex or as a symmetric 1:2 GroEL-GroES complex, although it remains uncertain which type is predominant under physiological conditions. To resolve this question, we studied the structure of the GroEL-GroES complex under physiological conditions by small-angle x-ray scattering, which is a powerful technique to directly observe the structure of the protein complex in solution. We evaluated molecular structural parameters, the radius of gyration and the maximum dimension of the complex, from the x-ray scattering patterns under various nucleotide conditions (3 mM ADP, 3 mM ATP gamma S, and 3 mM ATP in 10 mM MgCl(2) and 100 mM KCl) at three different temperatures (10 degrees C, 25 degrees C, and 37 degrees C). We then compared the experimentally observed scattering patterns with those calculated from the known x-ray crystallographic structures of the GroEL-GroES complex. The results clearly demonstrated that the asymmetric complex must be the major species stably present in solution under physiological conditions. On the other hand, in the presence of ATP (3 mM) and beryllium fluoride (10 mM NaF and 300 microM BeCl(2)), we observed the formation of a stable symmetric complex, suggesting the existence of a transiently formed symmetric complex during the chaperonin cycle.