Synthesis and biochemical characterization of naphthoquinone derivatives targeting bacterial histidine kinases.

Waldiomycin is an inhibitor of histidine kinases (HKs). Although most HK inhibitors target the ATP-binding region, waldiomycin binds to the intracellular dimerization domain (DHp domain) with its naphthoquinone moiety presumed to interact with the conserved H-box region. To further develop inhibitors targeting the H-box, various 2-aminonaphthoquinones with cyclic, aliphatic, or aromatic amino groups and naphtho [2,3-d] isoxazole-4,9-diones were synthesized. These compounds were tested for their inhibitory activity (IC50) against WalK, an essential HK for Bacillus subtilis growth, and their minimum inhibitory concentrations (MIC) against B. subtilis. As a result, 11 novel HK inhibitors were obtained as naphthoquinone derivatives (IC50: 12.6-305 µM, MIC: 0.5-128 µg ml-1). The effect of representative compounds on the expression of WalK/WalR regulated genes in B. subtilis was investigated. Four naphthoquinone derivatives induced the expression of iseA (formerly yoeB), whose expression is negatively regulated by the WalK/WalR system. This suggests that these compounds inhibit WalK in B. subtilis cells, resulting in antibacterial activity. Affinity selection/mass spectrometry analysis was performed to identify whether these naphthoquinone derivatives interact with WalK in a manner similar to waldiomycin. Three compounds were found to competitively inhibit the binding of waldiomycin to WalK, suggesting that they bind to the H-box region conserved in HKs and inhibit HK activity.

Development of a novel AAK1 inhibitor via Kinobeads-based screening.

A chemical proteomics approach using Ca2+/calmodulin-dependent protein kinase kinase (CaMKK) inhibitor-immobilized sepharose (TIM-063-Kinobeads) identified main targets such as CaMKKα/1 and ß/2, and potential off-target kinases, including AP2-associated protein kinase 1 (AAK1), as TIM-063 interactants. Because TIM-063 interacted with the AAK1 catalytic domain and inhibited its enzymatic activity moderately (IC50 = 8.51 µM), we attempted to identify potential AAK1 inhibitors from TIM-063-derivatives and found a novel AAK1 inhibitor, TIM-098a (11-amino-2-hydroxy-7H-benzo[de]benzo[4,5]imidazo[2,1-a]isoquinolin-7-one) which is more potent (IC50 = 0.24 µM) than TIM-063 without any inhibitory activity against CaMKK isoforms and a relative AAK1-selectivity among the Numb-associated kinases family. TIM-098a could inhibit AAK1 activity in transfected cultured cells (IC50 = 0.87 µM), indicating cell-membrane permeability of the compound. Overexpression of AAK1 in HeLa cells significantly reduced the number of early endosomes, which was blocked by treatment with 10 µM TIM-098a. These results indicate TIM-063-Kinobeads-based chemical proteomics is efficient for identifying off-target kinases and re-evaluating the kinase inhibitor (TIM-063), leading to the successful development of a novel inhibitory compound (TIM-098a) for AAK1, which could be a molecular probe for AAK1. TIM-098a may be a promising lead compound for a more potent, selective and therapeutically useful AAK1 inhibitor.

Conformation-Dependent Reversible Interaction of Ca2+/Calmodulin-Dependent Protein Kinase Kinase with an Inhibitor, TIM-063.

Ca2+/calmodulin-dependent protein kinase kinase (CaMKK), a Ca2+/CaM-dependent enzyme that phosphorylates and activates multifunctional kinases, including CaMKI, CaMKIV, protein kinase B/Akt, and 5'AMP-activated protein kinase, is involved in various Ca2+-signaling pathways in cells. Recently, we developed an ATP-competitive CaMKK inhibitor, TIM-063 (2-hydroxy-3-nitro-7H-benzo[de]benzo[4,5]imidazo[2,1-a]isoquinolin-7-one, Ohtsuka et al. Biochemistry 2020, 59, 1701-1710). To gain mechanistic insights into the interaction of CaMKK with TIM-063, we prepared TIM-063-coupled sepharose (TIM-127-sepharose) for association/dissociation analysis of the enzyme/inhibitor complex. CaMKKα/ß in transfected COS-7 cells and in mouse brain extracts specifically bound to TIM-127-sepharose and dissociated following the addition of TIM-063 in a manner similar to that of recombinant GST-CaMKKα/ß, which could bind to TIM-127-sepharose in a Ca2+/CaM-dependent fashion and dissociate from the sepharose following the addition of TIM-063 in a dose-dependent manner. In contrast to GST-CaMKKα, GST-CaMKKß was able to weakly bind to TIM-127-sepharose in the presence of EGTA, probably due to the partially active conformation of recombinant GST-CaMKKß without Ca2+/CaM-binding. These results suggested that the regulatory domain of CaMKKα prevented the inhibitor from interacting with the catalytic domain as the GST-CaMKKα mutant (residues 126-434) lacking the regulatory domain (residues 438-463) interacted with TIM-127-sepharose regardless of the presence or absence of Ca2+/CaM. Furthermore, CaMKKα bound to TIM-127-sepharose in the presence of Ca2+/CaM completely dissociated from TIM-127-sepharose following the addition of excess EGTA. These results indicated that TIM-063 interacted with and inhibited CaMKK in its active state but not in its autoinhibited state and that this interaction is likely reversible, depending on the concentration of intracellular Ca2+.

Recovery of lower oesophageal barrier function: a pilot study comparing a mixture of atropine and neostigmine and sugammadex: A randomised controlled pilot study.

BACKGROUND: The lower oesophageal sphincter (LOS) barrier serves to prevent regurgitation of gastric contents. Although general anaesthesia depresses its function, its recovery process during emergence from anaesthesia has not been systematically examined. OBJECTIVE: To explore whether recovery of lower oesophageal barrier function differed between patients receiving a mixture of 1 mg atropine and 2 mg neostigmine and those receiving 2 mg kg-1 sugammadex during emergence from anaesthesia. DESIGN: An unblinded randomised controlled pilot study. SETTING: A single university hospital from January 2016 to December 2018. PATIENTS: A total of 20 non-obese adult females undergoing minor surgery. INTERVENTION: The patients were randomly assigned to a group either receiving atropine and neostigmine or sugammadex for reversal of rocuronium. MAIN OUTCOME MEASURES: Through use of the high-resolution manometry technique, the lower oesophageal barrier pressure (PBAR: primary variable) defined as a pressure difference between pressures at the LOS and the stomach was measured at five distinguishable time points during emergence from total intravenous anaesthesia. A mixed effects model for repeated measures was used to test the hypothesis. RESULTS: In all patients baseline PBAR values were positive even under muscle paralysis and general anaesthesia before administration of reversal agents, and did not differ between the groups (P = 0.299). During recovery from muscle paralysis and general anaesthesia, PBAR (mean ±â€ŠSD) significantly increased (P = 0.004) from 17.0 ±â€Š2.9 to 21.0 ±â€Š5.0 mmHg in the atropine and neostigmine group (n = 8) and from 19.1 ±â€Š9.0 to 24.5 ±â€Š12.7 mmHg in the sugammadex group (n = 11). PBAR significantly increased immediately after return of consciousness in both groups, whereas return of muscle tone, lightening of anaesthesia and tracheal extubation did not change it. CONCLUSION: Recovery of the lower oesophageal barrier function does not differ between patients receiving either atropine and neostigmine or sugammadex and is completed after recovery of consciousness from general anaesthesia. TRIAL REGISTRATION: UMIN Clinical Trials Registry: UMIN000020500: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&recptno=R000023594&type=summary&language=E.

Development and Characterization of Novel Molecular Probes for Ca2+/Calmodulin-Dependent Protein Kinase Kinase, Derived from STO-609.

Ca2+/calmodulin-dependent protein kinase kinase (CaMKK) activates particular multifunctional kinases, including CaMKI, CaMKIV, and 5'AMP-activated protein kinase (AMPK), resulting in the regulation of various Ca2+-dependent cellular processes, including neuronal, metabolic, and pathophysiological pathways. We developed and characterized a novel pan-CaMKK inhibitor, TIM-063 (2-hydroxy-3-nitro-7H-benzo[de]benzo[4,5]imidazo[2,1-a]isoquinolin-7-one) derived from STO-609 (7H-benzimidazo[2,1-a]benz[de]isoquinoline-7-one-3-carboxylic acid), and an inactive analogue (TIM-062) as molecular probes for the analysis of CaMKK-mediated cellular responses. Unlike STO-609, TIM-063 had an inhibitory activity against CaMKK isoforms (CaMKKα and CaMKKß) with a similar potency (Ki = 0.35 µM for CaMKKα, and Ki = 0.2 µM for CaMKKß) in vitro. Two TIM-063 analogues lacking a nitro group (TIM-062) or a hydroxy group (TIM-064) completely impaired CaMKK inhibitory activities, indicating that both substituents are necessary for the CaMKK inhibitory activity of TIM-063. Enzymatic analysis revealed that TIM-063 is an ATP-competitive inhibitor that directly targets the catalytic domain of CaMKK, similar to STO-609. TIM-063 suppressed the ionomycin-induced phosphorylation of exogenously expressed CaMKI, CaMKIV, and endogenous AMPKα in HeLa cells with an IC50 of ∼0.3 µM, and it suppressed CaMKK isoform-mediated CaMKIV phosphorylation in transfected COS-7 cells. Thus, TIM-063, but not the inactive analogue (TIM-062), displayed cell permeability and the ability to inhibit CaMKK activity in cells. Taken together, these results indicate that TIM-063 could be a useful tool for the precise analysis of CaMKK-mediated signaling pathways and may be a promising lead compound for the development of therapeutic agents for the treatment of CaMKK-related diseases.

Differences of Recovery from Rocuronium-induced Deep Paralysis in Response to Small Doses of Sugammadex between Elderly and Nonelderly Patients.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Complete recovery from rocuronium-induced muscle paralysis with sugammadex is reported to be delayed in elderly patients. The authors tested a hypothesis that recovery from deep neuromuscular block with low-dose sugammadex is slower (primary hypothesis) and incidence of recurarization is higher (secondary hypothesis) in elderly patients than in nonelderly patients. METHODS: In anesthetized elderly (n = 20; 76.9 ± 5.0 yr of age) and nonelderly patients (n = 20; 53.7 ± 12.8 yr of age) under deep paralysis with rocuronium, change of train-of-four ratio per minute (primary outcome variable) was measured with an acceleromyograph neuromuscular monitor during spontaneous recovery from rocuronium-induced muscle paralysis (0.6 mg/kg) and after infusion of low-dose sugammadex (50 µg · kg · min). Recurarization was defined as the negative change of train-of-four ratio. RESULTS: Spontaneous train-of-four ratio recovery rate was significantly slower in the elderly group (median [25th percentile, 75th percentile]: 1.89 [1.22, 2.90] %/min) than in the nonelderly group (3.45 [1.96, 4.25] %/min, P = 0.024). Train-of-four ratio change rate in response to low-dose sugammadex was significantly slower in elderly (0.55 [-0.29, 1.54] %/min) than in the nonelderly group (1.68 [0.73, 3.13] %/min, P = 0.024). Incidence of recurarization was significantly higher in the elderly group than in the nonelderly group (35% vs. 5%, P = 0.044). Multiple linear regression analyses indicate that slower spontaneous train-of-four ratio recovery rate and impaired renal function are two major contributing factors that decrease train-of-four ratio change rate in response to low-dose sugammadex. CONCLUSIONS: Elderly patients are at greater risk for recurarization and residual muscle paralysis when low-dose sugammadex is administered.

Mask Ventilation during Induction of General Anesthesia: Influences of Obstructive Sleep Apnea.

BACKGROUND: Depending on upper airway patency during anesthesia induction, tidal volume achieved by mask ventilation may vary. In 80 adult patients undergoing general anesthesia, the authors tested a hypothesis that tidal volume during mask ventilation is smaller in patients with sleep-disordered breathing priorly defined as apnea hypopnea index greater than 5 per hour. METHODS: One-hand mask ventilation with a constant ventilator setting (pressure-controlled ventilation) was started 20 s after injection of rocuronium and maintained for 1 min during anesthesia induction. Mask ventilation efficiency was assessed by the breath number needed to initially exceed 5 ml/kg ideal body weight of expiratory tidal volume (primary outcome) and tidal volumes (secondary outcomes) during initial 15 breaths (UMIN000012494). RESULTS: Tidal volume progressively increased by more than 70% in 1 min and did not differ between sleep-disordered breathing (n = 42) and non-sleep-disordered breathing (n = 38) patients. In post hoc subgroup analyses, the primary outcome breath number (mean [95% CI], 5.7 [4.1 to 7.3] vs. 1.7 [0.2 to 3.2] breath; P = 0.001) and mean tidal volume (6.5 [4.6 to 8.3] vs. 9.6 [7.7 to 11.4] ml/kg ideal body weight; P = 0.032) were significantly smaller in 20 sleep-disordered breathing patients with higher apnea hypopnea index (median [25th to 75th percentile]: 21.7 [17.6 to 31] per hour) than in 20 non-sleep disordered breathing subjects with lower apnea hypopnea index (1.0 [0.3 to 1.5] per hour). Obesity and occurrence of expiratory flow limitation during one-hand mask ventilation independently explained the reduction of efficiency of mask ventilation, while the use of two hands effectively normalized inefficient mask ventilation during one-hand mask ventilation. CONCLUSIONS: One-hand mask ventilation is difficult in patients with obesity and severe sleep-disordered breathing particularly when expiratory flow limitation occurs during mask ventilation.

[Patient's Risk Factors for Perioperative Aspiration Pneumonia].

This article reviews patient's own risk factors for perioperative aspiration pneumonia. Maintaining the function of the lower esophageal sphincter (LES), the airway protective reflex, and the oral hygiene are the most important to prevent the pneumonia. The LES is adversely affected by excessive stomach distention, some medication given in perioperative periods, and habitual smoking, as well as pathological status such as esophageal hiatus hernia and achalasia. Postapoplectic patients may have insufficient airway protective reflex including swallowing and laryngeal reflex. It is emphasized that the perioperative oral care is increasing in its importance for the prevention of aspiration pneumonia.

Submental negative pressure application decreases collapsibility of the passive pharyngeal airway in nonobese women.

The pharyngeal airway is surrounded by soft tissues that are also enclosed by bony structures such as the mandible, maxilla, and cervical spine. The passive pharyngeal airway is therefore structurally analogous to a collapsible tube within a rigid box. Cross-sectional area of the tube is determined by transmural pressure, the pressure difference between intraluminal and extraluminal pressures. Due to a lack of knowledge on the influence of extraluminal soft tissue pressure on the human pharyngeal airway patency, we hypothesized that application of negative external pressure to the submental region decreases collapsibility of the passive pharynx, and that obese individuals have less response to the intervention than nonobese individuals. Static mechanical properties of the passive pharynx were compared before and during application of submental negative pressure in 10 obese and 10 nonobese adult women under general anesthesia and paralysis. Negative pressure was applied through use of a silicone collar covering the entire submental region and a vacuum pump. In nonobese subjects, application of submental negative pressure (-25 and -50 cmH2O) significantly decreased closing pressures at the retropalatal airway by 2.3 ± 3.2 cmH2O and 2.0 ± 3.0 cmH2O, respectively, and at the retroglossal airway by 2.9 ± 2.7 cmH2O and 3.7 ± 2.6 cmH2O, respectively, and the intervention stiffened the retroglossal pharyngeal airway wall. No significant mechanical changes were observed during application of submental negative pressure in obese subjects. Conclusively, application of submental negative pressure was found to decreases collapsibility of the passive pharyngeal airway in nonobese Japanese women.

How can we improve mask ventilation in patients with obstructive sleep apnea during anesthesia induction?

Recent evidence suggests the possible development of difficult mask ventilation in patients with obstructive sleep apnea. Based on our current understanding of the pathophysiology of pharyngeal airway obstruction in obstructive sleep apnea patients, we conclude that anesthesiologists can decrease respiratory complications during anesthesia induction by conducting careful pre-induction preparations, including body and head positioning and sufficient preoxygenation, and by using the two-hand mask ventilation technique with effective airway maneuvers and appropriate ventilator settings while continuously assessing ventilation status with capnography.

Effects of muscle relaxants on mask ventilation in anesthetized persons with normal upper airway anatomy.

BACKGROUND: Recent studies suggest advantages of muscle relaxants for facemask ventilation. However, direct effects of muscle relaxants on mask ventilation remain unclear because these studies did not control mechanical factors influencing ventilation. We tested a hypothesis that muscle relaxants, either rocuronium or succinylcholine, improve mask ventilation. METHODS: In anesthetized adult persons with normal upper airway anatomy, tidal volumes during facemask ventilation were measured while maintaining the neutral head and mandible positions and the airway pressures of a ventilator before and during muscle paralysis induced by either rocuronium (n=14) or succinylcholine (n=17). Tidal volumes of oral and nasal airway routes were separately measured with a custom-made oronasal portioning full facemask. Behavior of the oral airway was observed by an endoscope in six additional subjects receiving succinylcholine. RESULTS: Total, oral, and nasal tidal volumes did not significantly change at complete muscle paralysis with rocuronium. In contrast, succinylcholine significantly increased total tidal volumes at 60 s after its administration (mean±SD; 4.2±2.1 vs. 5.4±2.6 ml/kg, P=0.02) because of increases of ventilation through both airway routes. Abrupt tidal volume increase occurred more through oral airway route than nasal route. Dilation of the space at the isthmus of the fauces was endoscopically observed during pharyngeal fasciculation in all six subjects. CONCLUSIONS: Rocuronium did not deteriorate facemask ventilation, and it was improved after succinylcholine administration in association with airway dilation during pharyngeal fasciculation. This effect continued to a lesser degree after resolution of the fasciculation.

Lung/chest expansion contributes to generation of pleasantness associated with dyspnoea relief.

Pleasantness associated with dyspnoea relief or 'respiratory pleasure' is considered as a particular sensory experience. The purpose of this study is to elucidate the mechanism of generation of this particular sensory experience. After taking deep breaths during normal breathing, 35 healthy subjects received three different magnitudes of inspiratory loads (light: 8.4; moderate: 23.4; severe: 70.5 cm H2O/L/s) to induce dyspnoeic sensation. We found that (1) deep breaths during normal breathing rarely induce 'respiratory pleasure', (2) a sudden removal of dyspnoea alone is not sufficient to produce 'respiratory pleasure', and (3) the generation of 'respiratory pleasure' can be observed when a sudden removal of dyspnoea accompanies a large increase in tidal volume (V(T)). In addition, qualitative assessment of 'respiratory pleasure' showed that this sensation is compatible with a strong, positively valenced sensation. These findings indicate that an increase in V(T) after removal of respiratory loading plays a crucial role in generation of 'respiratory pleasure' that is a specific sensory-emotional experience.

Sitting posture decreases collapsibility of the passive pharynx in anesthetized paralyzed patients with obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is an independent risk factor for difficult and/or impossible mask ventilation during anesthesia induction. Postural change from supine to sitting improves nocturnal breathing in patients with OSA. The purpose of this study was to evaluate the effect of patient position on collapsibility of the pharyngeal airway in anesthetized and paralyzed patients with OSA. The authors tested the hypothesis that the passive pharynx is structurally less collapsible during sitting than during supine posture. METHOD: Total muscle paralysis was induced with general anesthesia in nine patients with OSA, eliminating neuromuscular factors contributing to pharyngeal patency. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. Comparison of static pressure-area plots between the supine and sitting (62° head-up) allowed assessment of the postural differences of the mechanical properties of the pharynx. RESULTS: : Maximum cross-sectional area was greater during sitting than during supine posture at both retropalatal (median (10th-90th percentile): 1.91 (1.52-3.40) versus 1.25 (0.65-1.97) cm) and retroglossal (2.42 (1.72-3.84) versus 1.75 (0.47-2.35) cm) airways. Closing pressure of the passive pharynx was significantly lower during sitting than supine posture. Differences of the closing pressures between the postures are 5.89 (3.73-11.6) and 6.74 (4.16-9.87) cm H2O, at retropalatal and retroglossal airways, respectively, and did not differ between the pharyngeal segments. CONCLUSIONS: Postural change from supine to sitting significantly improves collapsibility of pharyngeal airway in anesthetized and paralyzed patients with OSA.

Comparison of pain and dyspnea perceptual responses in healthy subjects.

Dyspnea and pain have a number of similarities. Recent brain imaging experiments showed that similar cortical regions are activated by the perceptions of dyspnea and pain. We tested the hypothesis that an individual's pain sensitivity might parallel the individual's dyspnea sensitivity. Studies were carried out in 52 young healthy subjects. Each subject experienced experimentally induced pain and dyspnea. Pain was induced by a cold-pressor test and dyspnea was induced by breathholding while the unpleasant experience of pain and dyspnea was assessed by using a Visual Analogue Scale (VAS). The times from the start of cold stimulation and breathholding to the onset of uncomfortable sensation (pain threshold time and the period of no respiratory sensation, respectively) and to the limit of tolerance (pain endurance time and total breathholding time, respectively) were also measured. In response to cold pain stimulation, a behavioral dichotomy (pain-tolerant and pain-sensitive) was observed. The period of no respiratory sensation was significantly shorter in the PS (pain-sensitive) group than in the PT (pain-tolerant) group (16.9+/-3.8 vs. 19.6+/-5.3 s: P<0.05), whereas no significant difference in the total breathholding time was found between the PT and PS groups. A significant correlation was observed between the pain threshold time and the period of no respiratory sensation in both the PT and PS groups. However, no significant association was observed between pain and dyspnea tolerance in both groups. In conclusion, an individual's pain threshold is correlated to the individual's dyspnea threshold, but the individual's pain tolerance is not consistently correlated to the individual's dyspnea tolerance.

THAM improves an experimentally induced severe dyspnea.

Inhibition of ventilatory drive may improve the sensation of dyspnea, because heightened ventilatory demand contributes to dyspnea. Tris-hydroxymethyl aminomethane (THAM) is an alkalizing agent that does not increase CO(2) production and exerts a depressant effect on respiration. The purpose of this study was to clarify the effect of THAM on dyspnea associated with increases in respiratory drive. We investigated the effects of THAM on dyspneic sensation produced by a combination of hypercapnia (mean PaCO(2)=52 mm Hg) and elastic loading (30 cm H(2)O/L) in 14 healthy subjects. The subjects were asked to rate their dyspneic sensation using a visual analogue scale (VAS) during the loaded breathing while monitoring ventilation using a pneumotachograph. THAM was infused at a rate of 0.4 mL/kg/minute for 10 minutes, and the effects of THAM on dyspnea and ventilation were evaluated by comparing the steady-state values of ventilatory variables and VAS score obtained before and after THAM administration. Administration of THAM corrected respiratory acidosis and was associated with significant improvements in VAS score and significant decreases in minute ventilation, respiratory frequency, and ventilatory drive. THAM administration greatly alleviates dyspneic sensation associated with the increase in respiratory drive and could be an effective therapy for treating severe dyspnea in patients with hypercapnia.

Sex differences in the effect of dyspnea on thermal pain threshold in young healthy subjects.

BACKGROUND: Previous study has demonstrated that dyspnea exerts inhibitory influence on pain, and empirical research supports the existence of sex differences in pain. To test the hypothesis that the inhibitory influence of dyspnea on the pain sensation may be less in females than in males, the authors investigated the sex differences in the responses of thermal pain threshold to dyspnea in healthy young subjects. METHODS: The authors measured changes in thermal pain threshold in 30 female subjects and 30 male subjects before and during dyspnea produced by a combination of hypercapnia and elastic loading, and compared the difference between males and females. RESULTS: The thermal pain threshold significantly increased during loaded breathing in male subjects (46.0 degrees +/- 1.3 degrees vs. 47.2 degrees +/- 1.2 degrees C; P < 0.01, baseline vs. loaded breathing), whereas no change was observed in female subjects (46.1 degrees +/- 1.3 degrees vs. 46.0 degrees +/- 1.4 degrees C; P > 0.1). No significant correlation was observed between the values of dyspneic visual analog scale and changes in thermal pain threshold. Comparison of the different phases of the menstrual cycle in female subjects also showed that there was no consistent effect of the particular phase on thermal pain threshold (45.7 degrees +/- 1.0 degrees vs. 46.1 degrees +/- 1.4 degrees C; P > 0.1, follicular phase vs. luteal phase during baseline; and 45.9 degrees +/- 1.1 degrees vs. 46.0 degrees +/- 1.7 degrees C; P > 0.1, follicular phase vs. luteal phase during loaded breathing). CONCLUSION: The inhibitory influence of dyspnea on the pain sensation is less in females than in males, but the sex difference may not be explained by female reproductive hormones alone.

Domino double Michael-Claisen cyclizations: a powerful general tool for introducing quaternary stereocenters at C4 of cyclohexane-1,3-diones and total synthesis of diverse families of sterically congested alkaloids.

Reactions of substituted acetone derivatives with acrylic acid esters (>200 mol %) in the presence of t-BuOK (200 mol %) in t-BuOH-THF (1:1 by volume) turned out to proceed as a cascade process consisting of the first Michael addition, the second Michael addition, and the last Claisen reaction to afford 4,4-disubstituted cyclohexane-1,3-diones. Only more substituted enolates play the role of a Michael donor in this cascade process, and therefore the ketone took up two alkoxycarbonylethyl groups on the same carbon bearing more substituents. Such intermediates were followed by intramolecular Claisen reactions leading to cyclohexane-1,3-diones bearing quaternary stereogenic centers at C(4), which bears an alkoxycarbonylethyl group and the substituent of the starting acetone derivatives. Thus-obtained 4,4-disubstituted cyclohexane-1,3-diones were successfully employed for total syntheses of intricate alkaloids of biological interest such as (+)-aspidospermidine, (+/-)-galanthamine, (+/-)-lycoramine, and (+/-)-mesembrine, all featuring quaternary stereogenic centers. DFT calculations provided us with clear-cut explanations for the observed chemoselectivity of the cascade process involving ketone-based enolates under thermodynamically controlled conditions.

Anatomical balance of the upper airway and obstructive sleep apnea.

BACKGROUND: Obesity and craniofacial abnormalities such as small maxilla and mandible are common features of patients with obstructive sleep apnea (OSA). The authors hypothesized that anatomical imbalance between the upper airway soft-tissue volume and the craniofacial size (rather than each alone) may result in pharyngeal airway obstruction during sleep, and therefore development of OSA. METHODS: Blind measurements of tongue cross-sectional area and craniofacial dimensions were performed through lateral cephalograms in 50 adult male patients with OSA and 55 adult male non-OSA subjects with various craniofacial dimensions. RESULTS: Maxillomandibular dimensions were matched between OSA and non-OSA groups. While the tongue was significantly larger in subjects with larger maxillomandible dimensions, OSA patients had a significantly larger tongue for a given maxillomandible size than non-OSA subjects. The hypothesis was also supported in subgroups matched for both body mass index and maxillomandible dimensions. CONCLUSIONS: Upper airway anatomical imbalance is involved in the pathogenesis of OSA.