Comparative Effects of α-, β-, and γ-Carbolines on Platelet Aggregation and Lipid Membranes

Cigarette smoking and alcohol consumption possibly affect platelet functions. To verify the hypothesis that some α-, β-, and γ-carboline components in cigarette smoke and alcoholic beverages may change platelet aggregability, their effects on human platelets were determined by aggregometry together with investigating their membrane effects by turbidimetry. Carbolines inhibited platelet aggregation induced by five agents with the potency being 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole > 3-amino-1-methyl-5H-pyrido[4,3-b]indole > 1-methyl-9H-pyrido[3,4-b]indole. The most potent 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole showed 50% aggregation-inhibitory concentrations of 6–172 μM. Both γ-carbolines interacted with phosphatidylcholine membranes to lower the lipid phase transition temperature with the potency correlating to the antiplatelet activity, suggesting that the interaction with platelet membranes to increase their fluidity underlies antiplatelet effects. Given their possible concentration and accumulation in platelets, γ- and β-carbolines would provide cigarette smokers and alcohol drinkers with reduced platelet aggregability, and they may be responsible for the occurrence of hemorrhagic diseases associated with heavy smoking and alcoholics

Drinking-Related Tetrahydroharmans Counteract the Membrane Effects of Local Anesthetic Lidocaine.

There is a general consensus in dentistry that successful local anesthesia is frequently difficult in habitual drinkers and alcoholic patients. Neuro-active tetrahydroharmans increase in human body fluids and tissues by consuming alcoholic beverages. To understand such reduced anesthetic efficacy by the drug interaction hypothesis, we studied the influences of drinking-related tetrahydroharmans on membrane fluidization as one of local anesthetic mechanisms. Liposomal membranes prepared with phosphatidylcholine and cholesterol were treated with lidocaine and different tetrahydroharmans separately and in combination, followed by measuring fluorescence polarization to determine their induced changes in membrane fluidity. In contrast to 0.1–2 mg/mL lidocaine, tetrahydroharmans decreased the fluidity of membrane preparations at ∼25 μg/mL with the potency being 1,2,3,4-tetrahydroharman ≫ 1,2,3,4-tetrahydronorharman. 1,2,3,4-Tetrahydroharman counteracted the membrane-fluidizing effects of 1 mg/mL lidocaine at physiologically relevant 0.25–2.5 ng/mL, whereas neither its 6-hydroxyl nor 7-hydroxyl metabolite did at 25–200 ng/mL. Such counteraction at a membrane lipid level may be responsible for the reduction of local anesthetic efficacy in drinkers because 1,2,3,4-tetrahydroharman increases in vivo by ingesting alcoholic beverages

Lipid peroxidation - inhibitory effects of perioperatively used drugs associated with their membrane interactions.

Objective: Oxidative/nitrative stress, an imbalance between oxidant production and antioxidant defense in the biological system, is induced not only by various diseases but also by anesthesia and surgical trauma. Since the choice of drugs is expected to reduce oxidative/nitrative stress in the perioperative period, the lipid peroxidation inhibition by different drugs associated with surgery was studied together with investigating one of their possible mechanisms.Methods: Lipid peroxidation-inhibitory effects were fluorometrically determined using the liposomes of diphenyl-1-pyrenylphosphine-incorporated lipid bilayers which were treated with 10-200 μM drugs and reference antioxidants, and then peroxidized with 20 μM peroxynitrite. Membrane interactions were evaluated by the drug- and antioxidant-induced changes in membrane fluidity which were determined by measuring the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene-labeled biomimetic membranes after treating with drugs and antioxidants at 1-200 μM.Results: All of the tested drugs concentration-dependently inhibited peroxynitrite-induced lipid peroxidation as well as antioxidant α-tocopherol, quercetin and (–)-epigallocatechin-3-gallate. The inhibition at 10 μM was greatest in propofol, followed by guaiacol, thiopental, thymol, phenol, midazolam, diazepam, lidocaine, eugenol, procaine, bupivacaine, ropivacaine, sevoflurane, ketamine, mepivacaine and prilocaine. Antioxidant drugs including propofol, local anesthetics and phenol derivatives, and reference antioxidants interacted with biomimetic membranes consisting of phospholipids and cholesterol to modify the membrane fluidity, while their membrane-interacting potencies did not necessarily correlate to their lipid peroxidation-inhibiting ones, suggesting that the interaction between drugs and membrane lipid bilayers, at least in part, underlies the lipid peroxidation inhibition.Conclusion: In addition to their inherent effects, propofol and other drugs to inhibit lipid peroxidation may be protective against perioperative oxidative/nitrative stress. The membrane interaction could be a guide for discovering novel antioxidant drugs

Comparative Interactions of Anesthetic Alkylphenols with Lipid Membranes.

Objective: While substituted phenols have a variety of pharmacological activity, the mechanism underlying their anesthetic effects remains uncertain especially about the critical target. We characterized the lipid membrane-interacting properties of different phenols by comparing with general anesthetic propofol and local anesthetics. Based on the results, we also studied the pharmacological effects possibly associated with their membrane interactivities. Methods: 1,6-Diphenyl-1,3,5-hexatriene-labeled lipid bilayer membranes were prepared with 1,2-dipalmitoyl-phosphatidylcholine as model membranes and with different phospholipids and cholesterol to mimic neuronal membranes. These membrane preparations were treated with phenols and anesthetics at 1 - 200 μM, followed by measuring the fluorescence polarization to determine the membrane interactivities to change membrane fluidity. Antioxidant effects were fluorometrically determined using diphenyl-1-pyrenylphosphine-incorporated liposomes which were treated with 10 - 100 μM phenols, and then peroxidized with 10 μM peroxynitrite. Results: Several phenols interacted with the model membranes and the neuronal mimetic membranes to increase their fluidity at 1 - 10 μM as well as lidocaine and bupivacaine did at 50 - 200 μM. Their comparative potencies were propofol > thymol > isothymol > guaiacol > phenol > eugenol, and bupivacaine > lidocaine, consistent with the rank order of neuro-activity. These phenols inhibited membrane lipid peroxidation at 10 and 100 μM with the potencies correlating to their membrane interactivities. Conclusion: The structure-specific membrane interaction is at least in part responsible for the pharmacology of anesthetic alkylphenols. Membrane-interacting antioxidant alkylphenols may be protective against the peroxynitrite-relating ischemia/reperfusion injur

Local anesthetic failure associated with inflammation: verification of the acidosis mechanism and the hypothetic participation of inflammatory peroxynitrite

The presence of inflammation decreases local anesthetic efficacy, especially in dental anesthesia. Although inflammatory acidosis is most frequently cited as the cause of such clinical phenomena, this has not been experimentally proved. We verified the acidosis mechanism by studying the drug and membrane lipid interaction under acidic conditions together with proposing an alternative hypothesis. Liposomes and nerve cell model membranes consisting of phospholipids and cholesterol were treated at different pH with lidocaine, prilocaine and bupivacaine (0.05%–0.2%, w/v). Their membrane-interactive potencies were compared by the induced-changes in membrane fluidity. Local anesthetics fluidized phosphatidylcholine membranes with the potency being significantly lower at pH 6.4 than at pH 7.4 (p < 0.01), supporting the acidosis theory. However, they greatly fluidized nerve cell model membranes even at pH 6.4 corresponding to inflamed tissues, challenging the conventional mechanism. Local anesthetics acted on phosphatidylserine liposomes, as well as nerve cell model membranes, at pH 6.4 with almost the same potency as that at pH 7.4, but not on phosphatidylcholine, phosphatidylethanolamine and sphingomyelin liposomes. Since the positively charged anesthetic molecules are able to interact with nerve cell membranes by ion-paring with anionic components like phosphatidylserine, tissue acidosis is not essentially responsible for the local anesthetic failure associated with inflammation. The effects of local anesthetics on nerve cell model membranes were inhibited by treating with peroxynitrite (50 μM), suggesting that inflammatory cells producing peroxynitrite may affect local anesthesia

Characteristic interactivity of landiolol, an ultra-short-acting highly selective β1-blocker, with biomimetic membranes: Comparisons with β1-selective esmolol and non-selective propranolol and alprenolol.

Although β1-blockers have been perioperatively used to reduce the cardiac disorders associated with general anesthesia, little is known about the mechanistic characteristics of ultra-short-acting highly selective β1-blocker landiolol. We studied its membrane-interacting property in comparison with other selective and non-selective β1-blockers. Biomimetic membranes prepared with phospholipids and cholesterol of varying compositions were treated with β1-selective landiolol and esmolol and non-selective propranolol and alprenolol at 0.5-200 μM. The membrane interactivity and the antioxidant activity were determined by measuring fluorescence polarization and by peroxidizing membrane lipids with peroxynitrite, respectively. Non-selective β1-blockers, but not selective ones, intensively acted on 1,2-dipalmitoylphosphatidylcholine (DPPC) liposomal membranes and cardiomyocyte-mimetic membranes to increase the membrane fluidity. Landiolol and its inactive metabolite distinctively decreased the fluidity of DPPC liposomal membranes, suggesting that a membrane-rigidifying effect is attributed to the morpholine moiety in landiolol structure but unlikely to clinically contribute to the β1-blocking effect of landiolol. Propranolol and alprenolol interacted with lipid raft model membranes, whereas neither landiolol nor esmolol. All drugs fluidized mitochondria-mimetic membranes and inhibited the membrane lipid peroxidation with the potency correlating to their membrane interactivity. Landiolol is characterized as a drug devoid of the interactivity with membrane lipid rafts relating to β2-adrenergic receptor blockade. The differentiation between β1-blocking selectivity and non-selectivity is compatible with that between membrane non-interactivity and interactivity. The mitochondrial membrane fluidization by landiolol independent of blocking β1-adrenergic receptors is responsible for the antioxidant cardioprotection common to non-selective and selective β1-blockers.Although β1-blockers have been perioperatively used to reduce the cardiac disorders associated with general anesthesia, little is known about the mechanistic characteristics of ultra-short-acting highly selective β1-blocker landiolol. We studied its membrane-interacting property in comparison with other selective and non-selective β1-blockers. Biomimetic membranes prepared with phospholipids and cholesterol of varying compositions were treated with β1-selective landiolol and esmolol and non-selective propranolol and alprenolol at 0.5-200 μM. The membrane interactivity and the antioxidant activity were determined by measuring fluorescence polarization and by peroxidizing membrane lipids with peroxynitrite, respectively. Non-selective β1-blockers, but not selective ones, intensively acted on 1,2-dipalmitoylphosphatidylcholine (DPPC) liposomal membranes and cardiomyocyte-mimetic membranes to increase the membrane fluidity. Landiolol and its inactive metabolite distinctively decreased the fluidity of DPPC liposomal membranes, suggesting that a membrane-rigidifying effect is attributed to the morpholine moiety in landiolol structure but unlikely to clinically contribute to the β1-blocking effect of landiolol. Propranolol and alprenolol interacted with lipid raft model membranes, whereas neither landiolol nor esmolol. All drugs fluidized mitochondria-mimetic membranes and inhibited the membrane lipid peroxidation with the potency correlating to their membrane interactivity. Landiolol is characterized as a drug devoid of the interactivity with membrane lipid rafts relating to β2-adrenergic receptor blockade. The differentiation between β1-blocking selectivity and non-selectivity is compatible with that between membrane non-interactivity and interactivity. The mitochondrial membrane fluidization by landiolol independent of blocking β1-adrenergic receptors is responsible for the antioxidant cardioprotection common to non-selective and selective β1-blockers

Exact solution of kinetic analysis for thermally activated delayed fluorescence materials

Research at Kyushu, Kyoto and St Andrews Universities was supported by EPSRC and JSPS Core to Core grants (JSPS Core-to-core Program; EPSRC grant number EP/R035164/1). Authors are also grateful for financial support from the Program for Building Regional Innovation Ecosystems of the Ministry of Education, Culture, Sports, Science and Technology, Japan, JST ERATO Grant JPMJER1305, JSPS KAKENHI JP20H05840, and Kyulux Inc.The photophysical analysis of thermally activated delayed fluorescence (TADF) materials has become instrumental to providing insight into their stability and performance, which is not only relevant for organic light-emitting diodes (OLED), but also for other applications such as sensing, imaging and photocatalysis. Thus, a deeper understanding of the photophysics underpinning the TADF mechanism is required to push materials design further. Previously reported analyses in the literature of the kinetics of the various processes occurring in a TADF material rely on several a priori assumptions to estimate the rate constants for forward and reverse intersystem crossing (ISC and RISC, respectively). In this report, we demonstrate a method to determine these rate constants using a three-state model together with a steady-state approximation and, importantly, no additional assumptions. Further, we derive the exact rate equations, greatly facilitating a comparison of the TADF properties of structurally diverse emitters and providing a comprehensive understanding of the photophysics of these systems.PostprintPostprintPeer reviewe

Bilateral Approach for Thoracoscopic Esophagectomy in a Patient with Esophageal Cancer and Solitary Posterior Thoracic Para-aortic Lymph Node Metastasis

We report a successful dissection of metastatic posterior thoracic para-aortic lymph node (No. 112aoP) via bilateral thoracoscopic surgery. With the anesthetized patient (a 73-year-old Japanese woman) in the prone position, two working ports were inserted for the left-side approach, and artificial pneumothorax was created. Thoracoscopic examination revealed a swollen LN posterior to the descending aorta. Fat and metastatic LNs posterior to the aorta were dissected from the aortic arch level to the diaphragm while preserving intercostal arteries. For the right-side approach, two working ports were inserted and a routine thoracoscopic esophagec-tomy was performed. Gastric conduit reconstruction was achieved laparoscopically. Operation time for the left thoracic procedure: 54 min; estimated blood loss: almost none. No recurrence was detected 24 months post-operatively. There are several surgical options for approaching No. 112aoP, including transhiatal, left thora-cotomy, and thoracoscopy. Although a wide dissection of the posterior thoracic para-aortic area has not been reported, it may be feasible and safe if the artery of Adamkiewicz and intercostal arteries are preserved. A min-imally invasive bilateral thoracoscopic approach for a thoracoscopic esophagectomy is safe and useful for esophageal cancer patients with solitary No. 112aoP metastasis