A Behavioral and Electroencephalographic Study of Anesthetic State Induced by MK-801 Combined with Haloperidol, Ketamine and Riluzole in Mice.

BACKGROUND: Ketamine is an intravenous anesthetic that acts as a channel blocker on the N-methyl-d-aspartate (NMDA) receptor, a glutamate receptor subtype. MK-801 is the most potent compound among noncompetitive NMDA receptor antagonists. Ketamine induces loss of the righting reflex (LORR) in rodents, which is one of the indicators of unconsciousness, whereas high doses of MK-801 produce ataxia, but not LORR. In contrast, we previously reported that MK-801 combined with a low dose of the dopamine receptor antagonist haloperidol-induced LORR in mice. To assess a neurophysiologically distinct brain state and demonstrate unconsciousness, electroencephalograms (EEG) need to be examined together with LORR. Therefore, we herein investigated EEG changes after the systemic administration of MK-801 alone or in combination with haloperidol, and compared them with those induced by ketamine, the glutamate release inhibitor riluzole, and the γ-aminobutyric acid type A receptor agonist propofol. METHODS: All drugs were intraperitoneally administered to adult male ddY mice (n = 168). General anesthesia was evaluated based on the righting reflex test. Animals who exhibited no righting for more than 30 seconds were considered to have LORR. In a separate group of mice, EEG of the primary visual cortex was recorded before and after the administration of MK-801 (3.0 mg/kg) alone or in combination with haloperidol (0.2 mg/kg), ketamine (150 mg/kg), riluzole (30 mg/kg), or propofol (240 mg/kg). The waveforms recorded were analyzed using EEG power spectra and spectrograms. RESULTS: The high dose of MK-801 alone did not induce LORR, whereas MK-801 combined with haloperidol produced LORR in a dose-dependent manner. Ketamine, riluzole, and propofol also dose-dependently induced LORR. In the EEG study, MK-801 alone induced a significant increase in δ power, while MK-801 plus haloperidol exerted similar effects on not only δ, but also θ and α power during LORR, suggesting that increases in δ, θ, and α power were necessary for LORR. The results obtained on MK-801 plus haloperidol were similar to those on ketamine in the behavioral and EEG studies, except for an increase in γ power by ketamine during LORR. Propofol significantly increased δ, θ, α, and ß power during LORR. However, the EEG results obtained using riluzole, which produced a unique pattern of lower amplitude activity spanning most frequencies, markedly differed from those with the other drugs. CONCLUSIONS: This study revealed differences in EEG changes induced by various sedatives. The results obtained on MK-801 alone and MK-801 plus haloperidol suggest the importance of dopamine transmission in maintaining the righting reflex.

New acoustic monitoring system quantifying aspiration risk during monitored anaesthesia care.

Respiratory monitoring is crucial during monitored anaesthesia care (MAC) to ensure patient safety. Patients undergoing procedures like gastrointestinal endoscopy and dental interventions under MAC have a heightened risk of aspiration. Despite the risks, no current system or device can evaluate aspiration risk. This study presents a novel acoustic monitoring system designed to detect fluid retention in the upper airway during MAC. We conducted a prospective observational study with 60 participants undergoing dental treatment under MAC. We utilized a prototype acoustic monitoring system to assess fluid retention in the upper airway by analysing inspiratory sounds. Water was introduced intraorally in participants to simulate fluid retention; artificial intelligence (AI) analysed respiratory sounds pre and post-injection. We also compared respiratory sounds pre-treatment and during coughing events. Coughing was observed in 14 patients during MAC, and 31 instances of apnoea were detected by capnography. However, 27 of these cases had breath sounds. Notably, with intraoral water injection, the Stridor Quantitative Value (STQV) significantly increased; furthermore, the STQV was substantially higher immediately post-coughing in patients who coughed during MAC. In summary, the innovative acoustic monitoring system using AI provides accurate evaluations of fluid retention in the upper airway, offering potential to mitigate aspiration risks during MAC.Clinical trial number: jRCTs 062220054.

Efficacy and safety of remimazolam besilate for sedation in outpatients undergoing impacted third molar extraction: a prospective exploratory study.

BACKGROUND: Dental treatments often cause anxiety, fear, and stress in patients. Intravenous sedation is widely used to alleviate these concerns, and various agents are employed for sedation. However, it is important to find safer and more effective sedation agents, considering the adverse effects associated with current agents. This study aimed to investigate the efficacy and safety of remimazolam besilate (hereinafter called "remimazolam") and to determine the optimal dosages for sedation in outpatients undergoing dental procedures. METHODS: Thirty-one outpatients aged 18-65 years scheduled for impacted third molar extraction were included in the study. Remimazolam was administered as a single dose of 0.05 mg/kg followed by a continuous infusion at a rate of 0.35 mg/kg/h, with the infusion rate adjusted to maintain a sedation level at a Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score of 2-4. The primary endpoint was the sedation success rate with remimazolam monotherapy, and the secondary endpoints included induction time, recovery time, time until discharge, remimazolam dose, respiratory and circulatory dynamics, and frequency of adverse events. RESULTS: The sedation success rate with remimazolam monotherapy was 100%. The remimazolam induction dose was 0.08 (0.07-0.09) mg/kg, and the anesthesia induction time was 3.2 (2.6-3.9) min. The mean infusion rate of remimazolam during the procedure was 0.40 (0.38-0.42) mg/kg/h. The time from the end of remimazolam administration to awakening was 8.0 (6.7-9.3) min, and the time from the end of remimazolam administration to discharge was 14.0 (12.5-15.5) min. There were no significant respiratory or circulatory effects requiring intervention during sedation. CONCLUSIONS: Continuous intravenous administration of remimazolam can achieve optimal sedation levels without significantly affecting respiratory or circulatory dynamics. The study also provided guidance on the appropriate dosage of remimazolam for achieving moderate sedation during dental procedures. Additionally, the study findings suggest that electroencephalogram monitoring can be a reliable indicator of the level of sedation during dental procedural sedation with remimazolam. TRIAL REGISTRATION: The study was registered in the Japan Registry of Clinical Trials (No. jRCTs061220052) on 30/08/2022.

Analgesia-based Sedation for Oral Surgery in Patients With Chronic Respiratory Obstructive Disease.

Chronic obstructive pulmonary disease (COPD) is a risk factor for postoperative cardiovascular and respiratory complications. Thus, intravenous sedation can be a better option than general anesthesia for surgery in patients with severe COPD. Herein, we present 2 cases of analgesia-based sedation in patients with severe COPD who underwent oral surgery. The current study aimed to discuss these cases to provide knowledge about the appropriate sedation management in patients with this disease. In the current cases, the patients received sufficient analgesia and minimum sedation (analgesia-based sedation). Moreover, dexmedetomidine was used for maintaining sedation and fentanyl for analgesic effects. Furthermore, we focused on providing the maximum analgesic effect of local anesthesia. The patients' vital signs were stable. They did not have any psychological or physical complaints, such as anxiety and pain, during the procedure. Then, they were discharged from the hospital without any complications. Thus, analgesia-based sedation can be an alternative option for oral surgery in patients with COPD.

Conditioned media from mesenchymal stromal cells and periodontal ligament fibroblasts under cyclic stretch stimulation promote bone healing in mouse calvarial defects.

BACKGROUND AIMS: When cells are exposed to stresses such as mechanical stimuli, they release growth factors and adapt to the surrounding environment H ere, we demonstrated that mechanical stimulation during culture affects the production of osteogenic and angiogenic factors. METHODS: Human bone marrow derived mesenchymal stromal cells (hMSCs) and human periodontal ligament fibroblasts (HPLFs ) were cultured under cyclic stretch stimulation for 24 h. Collected of the cells and conditioned media (CM), the gene and protein expression levels of osteogenic and angiogenic factors were evaluated. CM was also evaluated for angiogenic activity and calc ification ability. In in vivo study, CM was administered to a mouse calvarial defect model and histologically and radiologically evaluated. RESULTS: Quantitative real time polymerase chain reaction results showed that the expression of bone morphogenetic pro tein 2, 4 (BMP 2, 4), vascular endothelial growth factor A (VEGF A), and platelet derived growth factor AA (PDGF AA) was upregulated in the cyclic stretch stimulation group in comparison with the non stretch group in each cell type. Enzyme linked immunosor bent assay results revealed that the expression of BMP 2,4, VEGF A was upregulated in the cyclic stretch group in comparison with the non stretch group in each cell type. Only HPLFs showed significant difference in PDGF AA expression between the cyclic str etch and the non stretch group. Tube formation assay and Alizarin Red S staining results showed that angiogenic activity and calcification ability of CM was upregulated in the cyclic stretch stimulation group in comparison with the non stretch group in eac h cell type. CM was administered to the mouse calvarial defect model. Histological and radiological examination showed that the bone healing was promoted by CM from the cyclic stretch culture group. Immunohistological staining revealed that CM from cyclic stretch group have greater angiogenic effect than CM from the non stretch group. CONCLUSIONS: These results indicate that osteogenesis was promoted by CM obtained under cyclic stretch stimulation through the increase of angiogenesis in the mouse calvarial defect model.

The effect of macrophages on an atmospheric pressure plasma-treated titanium membrane with bone marrow stem cells in a model of guided bone regeneration.

Guided bone regeneration (GBR) is an established treatment. However, the mechanisms of GBR are not fully understood. Recently, a GBR membrane was identified that acts as a passive barrier to regenerate bone via activation and migration of macrophages (Mps) and bone marrow stem cells (BMSCs). Atmospheric pressure plasma treatment of the titanium membrane (APP-Ti) activated macrophages. The purpose of this study was to analyze whether macrophages attached to an APP-Ti membrane affected differentiation of BMSCs in a GBR model. Human THP-1 macrophages (hMps) were cultured on non-treated Ti (N-Ti) and APP-Ti membrane. Macrophage polarization was analyzed by RT-PCR and immunocytochemistry. Secreted proteins from hMps on N-Ti and APP-Ti were detected by LC/MS/MS. hBMSCs were co-cultured with hMps on N-Ti or APP-Ti and analyzed by osteogenic differentiation, Alizarin red S staining, and alkaline phosphatase (ALP) activity. N-Ti and APP-Ti membrane were also implanted into bone defects of rat calvaria. hMps on APP-Ti were polarized M2-like macrophages. hMps on N-Ti secreted plasminogen activator inhibitor-1 and syndecan-2, but hMps on APP-Ti did not. hBMSCs co-cultured with hMps on APP-Ti increased cell migration and gene expression of osteogenic markers, but suppressed mineralization, while ALP activity was similar to that of hMps on N-Ti in vitro. The volume of newly formed bone was not significantly different between N-Ti and APP-Ti membrane in vivo. M2 polarized hMps on APP-Ti suppressed osteogenic induction of hBMSCs in vitro. The indirect role of hMps on APP-Ti in newly formed bone was limited.

Chondroitin-4-sulfate transferase-1 depletion inhibits formation of a proteoglycan-rich layer and alters immunotolerance of bone marrow mesenchymal stem cells on titanium oxide surfaces.

Successful osseointegration is essential for dental implants. However, the complete molecular mechanism of osseointegration remains to be elucidated. In this study, we focused on the proteoglycan (PG)-rich layer between titanium oxides (TiOx) and bone, and chondroitin-4-sulfate transferase-1 (C4ST-1), which forms the sugar chain in PGs. Human bone marrow mesenchymal stem cells (hBMSCs) depleted of C4ST-1 were cultured on titanium (Ti) plates, and the interface between hBMSCs and TiOx was analyzed using transmission electron microscopy. Immunotolerance, proliferation, initial adhesion, and calcification of the cells were analyzed in vitro. At 14 days of cultivation, a PG-rich layer was observed between hBMSCs and TiOx. However, the PG-rich layer was reduced in C4ST-1-depleted hBMSCs on TiOx. Real-time RT-PCR showed that conditioned media increased the levels of expression of M1-macrophage markers in human macrophages. However, depletion of C4ST-1 did not affect calcification, cell proliferation, or initial cell adhesion on Ti plates. These results suggested that C4ST-1 in hBMSCs affects their immunotolerance and alters the formation of PG-rich layer formation on TiOx.

Kaempferol-immobilized titanium dioxide promotes formation of new bone: effects of loading methods on bone marrow stromal cell differentiation in vivo and in vitro.

BACKGROUND: Surface modification of titanium dioxide (TiO2) implants promotes bone formation and shortens the osseointegration period. Kaempferol is a flavonoid that has the capacity to promote osteogenic differentiation in bone marrow stromal cells. The aim of this study was to promote bone formation around kaempferol immobilized on TiO2 implants. METHODS: There were four experimental groups. Alkali-treated TiO2 samples (implants and discs) were used as a control and immersed in Dulbecco's phosphate-buffered saline (DPBS) (Al-Ti). For the coprecipitation sample (Al-cK), the control samples were immersed in DPBS containing 50 µg kaempferol/100% ethanol. For the adsorption sample (Al-aK), 50 µg kaempferol/100% ethanol was dropped onto control samples. The surface topography of the TiO2 implants was observed by scanning electron microscopy with energy-dispersive X-ray spectroscopy, and a release assay was performed. For in vitro experiments, rat bone marrow stromal cells (rBMSCs) were cultured on each of the TiO2 samples to analyze cell proliferation, alkaline phosphatase activity, calcium deposition, and osteogenic differentiation. For in vivo experiments, TiO2 implants placed on rat femur bones were analyzed for bone-implant contact by histological methods. RESULTS: Kaempferol was detected on the surface of Al-cK and Al-aK. The results of the in vitro study showed that rBMSCs cultured on Al-cK and Al-aK promoted alkaline phosphatase activity, calcium deposition, and osteogenic differentiation. The in vivo histological analysis revealed that Al-cK and Al-aK stimulated new bone formation around implants. CONCLUSION: TiO2 implant-immobilized kaempferol may be an effective tool for bone regeneration around dental implants.