E-Cadherin Is Expressed in Epithelial Cells of the Choroid Plexus in Human and Mouse Brains.

Evidence showing the functional significance of the choroid plexus is accumulating. Epithelial cells with tight and adherens junctions of the choroid plexus play important roles in cerebrospinal fluid production and circadian rhythm formation. Although specific types of cadherin expressed in adherens junctions of choroid plexus epithelium (CPE) have been examined, they remained uncertain. Recent mass spectrometry and immunolocalization analysis revealed that non-epithelial cadherins, P- and N-cadherins, are expressed in the lateral membrane of CPE, whereas E-cadherin expression has not been confirmed in CPE of humans or mice. In this study, we examined E-cadherin expression in CPE of mice and humans by RT-PCR, immunohistochemical-, and Western blotting analyses. We confirmed, by using RT-PCR analysis, the mRNA expression of E-cadherin in the choroid plexus of mice. The immunohistochemical expression of E-cadherin was noted in the lateral membrane of CPE of mice and humans. We further confirmed, in Western blotting, the specific immunoreactivity for E-cadherin. Immunohistochemically, the expression of E- and N-cadherins or vimentin was unevenly distributed in some CPE, whereas that of E- and P-cadherins or ß-catenin frequently co-existed in other CPE. These findings indicate that E-cadherin is expressed in the lateral membrane of CPE, possibly correlated with the expression of other cadherins and cytoplasmic proteins.

Income Change One Year after Confirmed Cancer Diagnosis and Its Associated Factors in Japanese Patients.

The number of patients who survive for a long time after cancer diagnosis is rapidly increasing; however, such patients experience major problems such as returning to work and changes in their income. This study aimed to determine the extent of income changes of cancer patients during the first year after cancer diagnosis and identify the influencing factors. From November 2019 through January 2020, we conducted a multicenter, self-administered anonymous survey of cancer patients in Kagawa Prefecture, Japan. The number of questionnaires collected was 483 (recovery rate 60.4%), and the number of participants who met the inclusion criteria was 72. Mean year-on-year income level one year since cancer diagnosis was 66% (SD: 32%; median: 70%). Cancer stage (p = 0.016), employment status at diagnosis (p = 0.006), and continued employment at the same workplace (p = 0.001) were associated with income change. Findings from this study showed that cancer patients lost one-thirds of their income one year after their diagnosis. It was related to the stage of their illness, employment status, and continued employment at their workplace just before the diagnosis. Employers should provide cancer patients with the support they need to keep them employed.

The number of physicians is related to the number of nighttime emergency surgeries in Japan: An ecological study.

PURPOSE: Increasing the number of physicians per population may improve the quality of medical services, but there are few reports on this aspect in the field of surgery. This study aimed to examine whether the number of physicians is associated with the number of nighttime emergency surgeries, which may be one of the indicators of the quality of medical services in the field of surgery. METHODS: This was a prefecture-based ecological study utilizing open data from Japanese government surveys conducted between 2015 and 2019. The relationship between the number of physicians and the number of nighttime emergency surgeries in 47 prefectures of Japan was evaluated by correlation analysis and panel data regression analysis. The correlation analysis was conducted between the number of physicians per 100,000 population and the number of nighttime emergency surgeries per 100,000 population per year in each prefecture in Japan. In the panel data regression analysis, panel data of the prefectures in Japan from 2015 to 2019 were created. We evaluated whether the number of physicians was related to the number of nighttime emergency surgeries, independent of the number of acute care beds per 100,000 population, population density, and the elderly population ratio. RESULTS: From the correlation analysis, the correlation coefficient between the number of physicians per 100,000 population and the number of nighttime emergency surgeries per 100,000 population was 0.533 (P < 0.001). In the panel data regression analysis, there was a significant association between the number of physicians per 100,000 population and the number of nighttime emergency surgeries per 100,000 population (P < 0.001). The regression coefficient (95% confidence interval) for the number of physicians per 100,000 population was 0.246 (0.113-0.378). CONCLUSION: The number of physicians is associated with the number of nighttime emergency surgeries.

General anesthesia with remimazolam for a pediatric patient with MELAS and recurrent epilepsy: a case report.

BACKGROUND: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a mitochondrial disease. We report here the safe use of remimazolam in a pediatric MELAS patient. CASE PRESENTATION: A 10-year-old girl (118 cm, 16 kg) was scheduled for an open gastrostomy to improve nutrition and epileptic seizure control. We induced and maintained general anesthesia with remimazolam, remifentanil, fentanyl, and rocuronium. We also performed a bilateral subcostal transversus abdominis plane block before the surgery. The surgery finished uneventfully. After we discontinued remimazolam administration, the patient woke up immediately but calmly without flumazenil. Epileptic seizures did not occur during intra- and early post-operative periods. CONCLUSION: Remimazolam enabled us to provide a pediatric MELAS patient with general anesthesia without causing delayed emergence or epileptic seizures.

The Association between Preoperative Blood Pressure Elevations and Postoperative Adverse Outcomes after Non-cardiac Surgery: A Single-center Retrospective Observational Study.

Blood pressure (BP) often rises before surgery. This study investigated whether BP elevation immediately before surgery was associated with adverse outcomes. Medical records of 11,732 patients (average age: 61 years; male: 47.4%) who underwent non-cardiac elective inpatient surgery under general anesthesia at Kagawa University Hospital between January 2011 and June 2019 were reviewed. Differences between the first BP values measured on the day before surgery and the first BP values in the operating room were defined as Δ systolic BP (ΔSBP) and Δ diastolic BP (ΔDBP). The relationships between ΔSBP/ΔDBP and 30-day mortality, 30-day readmission, and over-the-standard length of hospital stay (OSLOS) were assessed. OSLOS was defined as a hospital stay longer than mean+2 standard deviations and was calculated using the Japanese Diagnosis Procedure Combination data. In univariate analysis, the differences in ΔSBP and ΔDBP between the OSLOS and standard LOS groups were both 2 mmHg. In multivariate logistic regression analysis, only ΔDBP was associated with OSLOS. The adjusted odds ratio (95% confidence interval) for the largest quartile was 1.31 (1.02-1.69) (p<0.05). ΔDBP was associated with OSLOS; however, there may be little need to worry about large ΔSBPs and ΔDBPs in clinical practice.

Physiological Modeling of Concentration-Effect Relationship for Nondepolarizing Neuromuscular Blocking Drugs.

This paper reports modeling of physiological processes of neuromuscular transmission considering effects of nondepolarizing neuromuscualr blocking drugs (NDNBs) used during general anesthesia. NDNBs are considered to act by interacting with acetylcohine receptors located at pre- and post-junctional sites. This paper proposes an extension of the standard model of synaptic depression used in the field of neuroscience to describe the pre-junctional effect of NDNBs. The extended model is then combined with a previously proposed model of the post-junctional effect to simulate the whole process of neuromuscular transmission. The derived model can be used to predict pharmacologic relationship between the drug concentration and its actual effect of NDNBs. Specifically, the model firstly enables the estimation of Post-tetanic Count (PTC), a clinically used monitoring measure for deep neuromuscular blockade (NMB). The effectiveness of the derived model is discussed by comparing simulation results with clinical data obtained from a patient undergoing a surgical operation.

Immunoreactivities for hepcidin, ferroportin, and hephaestin in astrocytes and choroid plexus epithelium of human brains.

Iron plays essential roles in the central nervous system. However, how the iron level is regulated in brain cells including glia and neurons remains to be fully clarified. In this study, the localizations of hepcidin, ferroportin, and hephaestin, which are known to be involved in iron efflux, were immunohistochemically examined in autopsied human brains. Immunoreactivities for hepcidin and ferroportin were observed in granular structures within the cytoplasm of reactive astrocytes and epithelial cells of the choroid plexus. Granular structures showing immunoreactivities for hepcidin and ferroportin were also stained with antibodies for early endosome antigen 1 (EEA1). In addition, immunoreactivity for hephaestin was observed in the cytoplasm of epithelial cells of the choroid plexus as well as reactive astrocytes. Immunoreactivity for hephaestin in the cytoplasm of reactive astrocytes was occasionally colocalized with immunoreactivity for EEA1, while that of hephaestin was frequently observed in the cytoplasm showing no immunoreactivity for EEA1. These findings suggest that immunoreactivities for hepcidin and ferroportin are localized in close proximity to granular structures showing immunoreactivity for EEA1 in the cytoplasm of human brain astrocytes. They also suggest that immunoreactivity of hephaestin is localized in the cytoplasm of the choroid plexus epithelium as well as reactive astrocytes of human brains.

Lung-thorax compliance measured during a spontaneous breathing trial is a good index of extubation failure in the surgical intensive care unit: a retrospective cohort study.

BACKGROUND: Extubation failure is associated with mortality and morbidity in the intensive care unit. Ventilator weaning protocols have been introduced, and extubation is conducted based on the results of a spontaneous breathing trial. Room for improvement still exists in extubation management, and additional objective indices may improve the safety of the weaning and extubation process. Static lung-thorax compliance reflects lung expansion difficulty that is caused by several conditions, such as atelectasis, fibrosis, and pleural effusion. Nevertheless, it is not used commonly in the weaning and extubation process. In this study, we investigated whether lung-thorax compliance is a good index of extubation failure in adults even when patients pass a spontaneous breathing trial. METHODS: In a single-center, retrospective cohort study, patients over 18 years of age were mechanically ventilated, weaned with proportional assist ventilation, and underwent a spontaneous breathing trial process in surgical intensive care units of Kagawa University Hospital from July 2014 to June 2016. Extubation failure was the outcome measure of the study. We defined extubation failures as when patients were reintubated or underwent non-invasive positive-pressure ventilation within 24 h after extubation. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the clinical involvement of several parameters. The area under the curve (AUC) was calculated to assess the discriminative power of the parameters. RESULTS: We analyzed 173 patients and compared the success and failure groups. Most patients (162, 93.6%) were extubated successfully, and extubation failed in 11 patients (6.4%). The averages of lung-thorax compliance values in the success and failure groups were 71.9 ± 23.0 and 43.3 ± 14.6 mL/cmH2O, respectively, and were significantly different (p < 0.0001). In the ROC curve analysis, the AUC was highest for lung-thorax compliance (0.862), followed by the respiratory rate (0.821), rapid shallow breathing index (0.781), Acute Physiology and Chronic Health Evaluation II score (0.72), heart rate (0.715), and tidal volume (0.695). CONCLUSIONS: Lung-thorax compliance measured during a spontaneous breathing trial is a potential indicator of extubation failure in postoperative patients.

Effect of the volatile anesthetic agent isoflurane on lateral diffusion of cell membrane proteins.

The volatile anesthetic isoflurane (ISO) has previously been shown to increase the fluidity of artificial lipid membranes, but very few studies have used biological cell membranes. Therefore, to investigate whether ISO affects the mobility of membrane proteins, fluorescence-labeled transferrin receptor (TfR) and glycosylphosphatidylinositol (GPI)-anchored protein were expressed in human embryonic kidney 293T cells and neural cells and lateral diffusion was examined using fluorescence recovery after photobleaching. Lateral diffusion of the TfR increased with ISO treatment. On the other hand, there was no effect on GPI-anchored protein. We also used GC/MS to confirm that there was no change in the concentration of ISO due to vaporization during measurement. These results suggest that ISO affects the mobility of transmembrane protein molecules in living cells.

Guanylyl Cyclase A in Both Renal Proximal Tubular and Vascular Endothelial Cells Protects the Kidney against Acute Injury in Rodent Experimental Endotoxemia Models.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Natriuretic peptides are used, based on empirical observations, in intensive care units as antioliguric treatments. We hypothesized that natriuretic peptides prevent lipopolysaccharide-induced oliguria by activating guanylyl cyclase A, a receptor for natriuretic peptides, in proximal tubules and endothelial cells. METHODS: Normal Sprague-Dawley rats and mice lacking guanylyl cyclase A in either endothelial cells or proximal tubular cells were challenged with lipopolysaccharide and assessed for oliguria and intratubular flow rate by intravital imaging with multiphoton microscopy. RESULTS: Recombinant atrial natriuretic peptide efficiently improved urine volume without changing blood pressure after lipopolysaccharide challenge in rats (urine volume at 4 h, lipopolysaccharide: 0.6 ± 0.3 ml · kg · h; lipopolysaccharide + fluid resuscitation: 4.6 ± 2.0 ml · kg · h; lipopolysaccharide + fluid resuscitation + atrial natriuretic peptide: 9.0 ± 4.8 ml · kg · h; mean ± SD; n = 5 per group). Lipopolysaccharide decreased glomerular filtration rate and slowed intraproximal tubular flow rate, as measured by in vivo imaging. Fluid resuscitation restored glomerular filtration rate but not tubular flow rate. Adding atrial natriuretic peptide to fluid resuscitation improved both glomerular filtration rate and tubular flow rate. Mice lacking guanylyl cyclase A in either proximal tubules or endothelium demonstrated less improvement of tubular flow rate when treated with atrial natriuretic peptide, compared with control mice. Deletion of endothelial, but not proximal tubular, guanylyl cyclase A augmented the reduction of glomerular filtration rate by lipopolysaccharide. CONCLUSIONS: Both endogenous and exogenous natriuretic peptides prevent lipopolysaccharide-induced oliguria by activating guanylyl cyclase A in proximal tubules and endothelial cells.

Immunoreactivity of urate transporters, GLUT9 and URAT1, is located in epithelial cells of the choroid plexus of human brains.

It has been suggested that urate plays a protective role in neurons, while hyperuricemia is correlated with atherosclerosis and cardiovascular disease. However, whether there is a system that directly transports urate into the brain remains to be clarified. In this study, the localization of glucose transporter 9 (GLUT9) and urate transporter 1 (URAT1), which are known to be representative reabsorptive urate transporters, was immunohistochemically examined in autopsied human brains. Immunoreactivity of GLUT9 was observed on the apical side of the cytoplasm of epithelial cells in the choroid plexus and in the cilia of ependymal cells of the human brain. Immunoreactivity of URAT1 was observed on the basolateral side of the cytoplasm of epithelial cells in the choroid plexus. In addition, immunoreactivity of GLUT9 and URAT1 was not observed in microvessels of the human brains. The choroid plexus and renal proximal tubule were similar in having a polarized distribution of these two transporters with the two transporters on opposite membranes, but the two transporters' distribution differs between the choroid plexus and the kidney in terms of which membrane (apical/basal) expresses which transporter. These findings support the hypothesis of the direct transport of intravascular urate into the central nervous system through the choroid plexus.

Sex differences in attachment to spouses among older Japanese couples.

AIM: Attachment among older adults can partially explain sex differences in bereavement outcomes, but there is currently little evidence regarding this. The aim was to quantify sex differences in the proportion of spouses as attachment figures among older couples. METHODS: We carried out a secondary analysis of cross-sectional questionnaire survey data. The dataset included information about 5137 respondents aged 65 years or older in Kanonji and Mitoyo, two rural cities in Kagawa prefecture, Japan; those who were never married or were widowed or divorced were excluded. The questionnaire asked participants whom they most want to be close by when they die (this person was defined as an "attachment figure"), and compared the proportion of older people of each sex who named their spouse. We used multiple logistic regression analyses to examine the independent association of sex with the proportion of spouses as attachment figures. RESULTS: Of the 2513 male respondents, 1494 (59.5%) answered "spouse." Of the 2624 female respondents, 904 (34.5%) answered "spouse." Multiple logistic regression analyses adjusted for age, live-in children, annual income, participation in community activities, presence of a long-term primary care doctor, anxiety about death and preferences for place of death showed that men had a higher probability of attachment to spouses than women (odds ratio 2.83, 95% confidence interval 2.43-3.31). CONCLUSIONS: Spouses are more likely to be attachment figures for men than for women. The present study supports the theory that sex differences in attachment might partially explain the differences in the bereavement effect between sexes among older people. Geriatr Gerontol Int 2017; 17: 834-838.

Comparison of general anesthesia and monitored anesthesia care in patients undergoing breast cancer surgery using a combination of ultrasound-guided thoracic paravertebral block and local infiltration anesthesia: a retrospective study.

PURPOSE: The aim of this study was to compare post-anesthesia recovery time and the incidence of hypotension episodes during anesthesia in breast cancer surgery between general anesthesia (GA) and monitored anesthesia care (MAC) retrospectively. Both techniques were combined with ultrasound-guided paravertebral block (US-PVB) and local infiltration anesthesia (LIA). METHODS: We reviewed the medical records of patients who received US-PVB for breast cancer surgery retrospectively and divided them into two groups based on the method of anesthetic management. In the GA group, anesthesia was induced using propofol and maintained by sevoflurane inhalation via a laryngeal mask airway after US-PVB was performed under sedation with midazolam. In the MAC group, US-PVB and surgery were carried out under sedation with propofol and remifentanil and supplemental oxygen through a facemask. All patients in both groups breathed spontaneously and received US-PVB and LIA with 0.5 % ropivacaine and diclofenac suppository for pain relief. RESULTS: Times from post-anesthesia care unit admission to fluid intake (mean ± SD; 79 ± 34 vs. 99 ± 33 min, P = 0.034) and gait (77 ± 45 vs. 109 ± 45 min, P = 0.013) were significantly shorter in the MAC group (n = 29) than in the GA group (n = 29). Average systolic blood pressure (SBP) was significantly lower (89 ± 11 vs. 99 ± 16 mmHg, P = 0.011) and the incidence of hypotension (SBP < 70 mmHg) was higher (52 vs. 21 %, P = 0.014) in the GA group than in the MAC group during anesthesia. CONCLUSION: MAC with US-PVB and LIA exhibited faster post-anesthesia recovery and a lower incidence of hypotension episodes during anesthesia than GA with US-PVB and LIA in breast cancer surgery.

[Transient Femoral Nerve Palsy after Ilioinguinal-Iliohypogastric Nerve Block: Comparison of Ultrasound-guided and Landmark-based Techniques in Adult Inguinal Hernia Surgery].

BACKGROUND: Transient femoral nerve palsy (TFNP) is a well-known complication associated with ilioinguinal-iliohypogastric nerve block (IINB). We compared the incidence of TFNP after ultrasound-guided IINB and that after anatomical landmark-based IINB. METHODS: We reviewed medical records of adult patients (ASA-PS 1-3, Age 21-87) who had received inguinal hernia surgery under general anesthesia and LINB retrospectively. IINB was performed using 0.5% ropivacaine either by ultrasound-guidance (US group, n = 16) or by landmark-based technique (LM group, n =17). TFNP was defined as sensory loss in the anterior aspect of the thigh or weakness of quadriceps femoris muscle in the nerve-blocked side. RESULTS: The frequency of TFNP in US group (6%) was lower than that in LM group (41%) in the post-anesthesia care unit (P = 0.019). TFNP symptom was resolved completely on the morning after surgery. The incidence of severe-intermediate postoperative pain and analgesic requirement were not different between the two groups. CONCLUSIONS: This study revealed that ultrasound-guided technique is effective to lower the incidence of TFNP after IINB in adult inguinal hernia surgery.

[Monitored Anesthesia Care for Respiratory Endoscopy].

Sedation and/or analgesia are required during respiratory endoscopy procedure to reduce the patient's anxiety, unpleasantness and pain. At present most of diagnostic respiratory endoscopy cases are carried out outside the operating room without the involvement of anesthesiologists in Japan. Inadequate anesthesia/sedation may cause patient's discomfort and/or serious injury. Anesthesiologists are expected to play a part in the sedation and analgesia education/training for nonanesthesiologists to ameliorate patient satisfaction and safety. Interventional endoscopy procedures are more invasive and painful than simple diagnostic ones for patients, and sometimes result in a crisis such as respiratory tract bleeding and airway obstruction. Since the number of interventional cases and high-risk patients will increase with the society aging, peri-procedure management by anesthesiologists or monitored anesthesia care will become popular in the future.

Aldehyde dehydrogenase 2 deficiency increases resting-state glutamate and expression of the GluN1 subunit of N-methyl-D-aspartate receptor in the frontal cortex of mice.

Our previous study showed that Aldh2-knockout (Aldh2-KO) mice, an animal model of inactive aldehyde dehydrogenase 2 (ALDH2), have better spatial memory when compared with wild-type (WT) mice. Given that the neurotransmitter glutamate has been associated with learning and memory, the goal of the present study was to investigate whether the strain-dependent difference in spatial memory was associated with changes in glutamate transmitter levels or receptor function in the frontal cortex of Aldh2-KO and WT mice. Thus, we first measured extracellular glutamate levels in free-moving mice using microdialysis. Second, we studied protein expression of the N-methyl-D-aspartate (NMDA) receptor (GluN1) subunit and the α-amino-3-hydroxy-5 methylisoxazole-4-propionic acid (AMPA) receptor (GluA1) subunit in lipid raft fractions using Western blot (WB). The samples were collected for WB, and lipid rafts were prepared from the insoluble fraction of homogenate tissue. Protein concentration was measured in the whole cell lysate (WCL) and in five separate lipid raft fractions. Cholesterol was also measured in all fractions 1-5. The microdialysis study revealed that basal glutamate concentration in the dialysates was approximately three-fold (0.27 ± 0.12 µM) higher in Aldh2-KO mice than in WT (0.10 ± 0.03 µM) mice. We also found an increase in the expression of GluN1 in Aldh2-KO mice compared with WT mice, both in the WCL and fraction 5, but GluA1 levels were unchanged as measured by WB. Our novel findings provide the first evidence for the role of ALDH2 in glutamate release and GluN1 protein expression in the frontal cortex. The observed strain differences in glutamate levels and GluN1 expression may suggest that enhanced glutamatergic function facilitates improved spatial memory in Aldh2-KO mice and such observation deserves further investigation.

Case of vascular air embolism during holmium laser enucleation of the prostate.

Vascular air embolism is a rare complication during transurethral surgery. A case of air embolism during holmium laser enucleation of the prostate in a 76-year-old man is presented. During the step of morcellation, the patient's blood pressure suddenly oscillated up and down, and end-tidal CO2 and arterial saturation decreased. Transesophageal and transthoracic echocardiography showed air collection in the right atrium. It was also discovered that incorrect assembly of the tube from the morcellator caused rapid entrainment of air into the vein. Computed tomography and abdominal X-ray showed niveau formation in the femoral vein and air collection in the pelvic retroperitoneal space. The patient recovered with careful observation and was discharged 7 days after the operation with no sequelae. This report is presented to remind urologists of this unusual complication that can occur during holmium laser enucleation of the prostate procedures.

Effort-reward imbalance and low back pain among eldercare workers in nursing homes: a cross-sectional study in Kagawa Prefecture, Japan.

OBJECTIVES: To clarify effort-reward imbalance among eldercare workers in nursing homes and to examine the association between the effort-reward imbalance (ERI) and low back pain (LBP) among them. METHODS: A total of 549 questionnaires were distributed to a random sample comprising 23% of the 79 special elderly nursing homes in Kagawa in 2013. A total of 467 eldercare workers (response rate 85%) participated in this study. Of the 467 eligible respondents, 372 (80%) completed all items of the ERI questionnaire. Complete data were available for 342 (73%) eldercare workers. RESULTS: Of the 342 respondents, 215 (63%) had LBP at the time of the study, and 291 (85%) showed a critical "high cost/low gain" condition as determined by an effort-reward ratio >1. Multiple logistic regression analyses adjusted for age, gender, previous LBP experience, high-risk work and K6 score showed that eldercare workers with a high ERI had a higher risk for LBP than workers with a low ERI (OR, 1.96; 95% CI, 1.02-3.77). CONCLUSIONS: Most eldercare workers have a high ERI, and their LBP is associated with their ERI. Balancing effort and reward may be an important factor for improving LBP among eldercare workers in nursing homes.

Hypnosis control based on the minimum concentration of anesthetic drug for maintaining appropriate hypnosis.

This paper proposes a novel hypnosis control method using Auditory Evoked Potential Index (aepEX) as a hypnosis index. In order to avoid side effects of an anesthetic drug, it is desirable to reduce the amount of an anesthetic drug during surgery. For this purpose many studies of hypnosis control systems have been done. Most of them use Bispectral Index (BIS), another hypnosis index, but it has problems of dependence on anesthetic drugs and nonsmooth change near some particular values. On the other hand, aepEX has an ability of clear distinction between patient consciousness and unconsciousness and independence of anesthetic drugs. The control method proposed in this paper consists of two elements: estimating the minimum effect-site concentration for maintaining appropriate hypnosis and adjusting infusion rate of an anesthetic drug, propofol, using model predictive control. The minimum effect-site concentration is estimated utilizing the property of aepEX pharmacodynamics. The infusion rate of propofol is adjusted so that effect-site concentration of propofol may be kept near and always above the minimum effect-site concentration. Simulation results of hypnosis control using the proposed method show that the minimum concentration can be estimated appropriately and that the proposed control method can maintain hypnosis adequately and reduce the total infusion amount of propofol.