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BACKGROUND/AIM To evaluate complications and risk factors associated with transumbilical incision as an organ removal site in laparoscopic pancreatectomy (LP). PATIENTS AND METHODS In total, 52 patients who underwent LP between 2009 and 2017 were included in this study. The development of superficial surgical site infection (SSI) and transumbilical port-site incisional hernia was recorded. RESULTS None of the patients had SSI. However, three (5.77%) presented with transumbilical incisional hernia. No variables were significantly associated with the risk of transumbilical incisional hernia. CONCLUSION No evident risk factors correlated with hernia formation. Hence, incisional hernia might have occurred at a certain probability. In some cases, it was caused by technical problems. However, the use of transumbilical incision as an organ removal site was feasible, and a new incision for organ removal alone was not required.

Background Hepatectomy for liver cirrhosis patients requires skillful surgical technique and careful attention because of the fibrotic parenchyma, elevated portal pressure, and impaired coagulation. This report evaluated short- and long-term outcomes for liver cirrhosis patients receiving precoagulation therapy on the parenchymal transection plane, compared with noncoagulation cases. Methods Seventy-three patients diagnosed with cirrhosis via postoperative pathological findings were selected after reviewing 887 hepatectomy patient files. They were divided into a precoagulation group (n = 20) and a noncoagulation group (n = 53). There were no significant differences in patient and tumor factors between 2 groups. Results The precoagulation group had significantly less blood loss compared with noncoagulation group [282 vs 563g (P < 0.05)], shorter operative time [214 vs 276 min (P = 0.06)], and shorter postoperative hospital stays [14.5 vs 22.5 days (P = 0.12)]. The median recurrence free survival rates time in the pre-coagulation group (733 days) was significantly longer than that in the non-coagulation group (400 days) (P < 0.05). Overall survival rates showed rates showed no difference between the 2 groups (P = 0.62). Conclusions Precoagulation therapy may be the a preferred treatment application for hepatectomy patients with severe liver fibrosis.

Background: Tokyo Guidelines 2018 recommend early surgery for acute cholecystitis. However, some elective surgery cases depend on complications or facility conditions. In this study, we retrospectively analyzed the cases of elective surgery.Methods: This study included 345 patients who underwent laparoscopic cholecystectomy (LC) at our hospital between January 2019 and December 2020. Eighty-three patients underwent LC four days or more after conservative treatment. The elective LC cases were divided into two groups: Early group (4-90 days after onset, n=36) and Delayed group (91+ days after onset, n=31). Percutaneous transhepatic gallbladder drainage cases (n=16) were excluded.Results: The operative times were significantly shorter in the Delayed group (91.2 min, p=0.0108) than the Early group (117 min). However, the amount of blood loss was not significantly different between the two groups. Furthermore, the length of hospital stay was shorter in the Delayed group (3.4 days, p=0.0436) than in the Early group (5.9 days).There were no significant differences in the incidence of complications or the rate of conversion; however, the rates of these two factors were reduced in the Delay group compared to the Early group.Conclusions: If it has become challenging to perform urgent/early LC within three days, due to prior conservative treatment for acute cholecystitis, the operative time and length of hospital stay could be reduced by delaying LC for more than 90 days after the onset. In addition, postoperative complications would not occur, and the conversion rate may be reduced to a low level.

Background/aim To evaluate the complication rates and risk factors associated with transumbilical wounds and investigate the usefulness of an incision for organ removal in laparoscopic hepatectomy (Lap-H). Patients and methods We enrolled 42 patients who underwent Lap-H excluding a small partial resection in our hospital between 2013 and 2018. The occurrences of superficial surgical site infection (SSI) and transumbilical port-site incisional hernia were recorded. Results SSI was not observed, and hernia occurred in 3 patients (7.14%). Univariate analysis revealed that body mass index (BMI) (p=0.004) was significantly associated with the risk of hernia formation. Conclusion High BMI is a risk factor for hernia formation in patients undergoing Lap-H with transumbilical incision; hence, wound closure should be performed carefully. The construction of the transumbilical wound for organ removal was feasible with rationality, with no need to create a new wound.

Recently, virtual navigation system has been applied to hepatic surgery, enabling better visualization of intrahepatic vascular branches and location of tumor. Intraoperative ultrasonography (IOUS) is the most common form of image guidance during liver surgery. However, during laparoscopic hepatectomies (LH), IOUS has several limitations and its reliability has been poorly evaluated. The objective of this work is to evaluate VRCT (virtual real-time CT-guided volume navigation) during LH. This system aims to provide accurate anatomical orientation for surgeons enhancing the safety of LH. Twenty-seven hepatic neoplasms were resected laparoscopically at our institution under reference guidance of VRCT. During operation, electromagnetic tracking of the surgical instrument was used for navigating the direction of accurate liver transection. Twenty-six (96.3%) of the 27 lesions (mean diameter 11 mm) were successfully performed under VRCT guidance. Average registration time was

Background/aim This study investigated the use of near-infrared fluorescent imaging for securing safe margins during liver resection. Patients and methods This study included 125 patients who underwent liver tumor resection in 2014-2018. Indocyanine green testing was performed 2-14 days before surgery. Histopathological specimens of hepatocellular carcinoma (HCC) and colorectal liver metastasis (CRLM) were evaluated using fluorescent microscopy. Results Fluorescence microscopy identified signals in 26/53 (49.0%) and 36/72 (50%) cases of HCC and CRLM, respectively. HCC demonstrated total, partial, rim, and combined fluorescence patterns; CRLM uniformly demonstrated rim fluorescence. Although rim fluorescence was seen in both HCC and CRLM, no malignancy was confirmed pathologically in the peritumoral area demonstrating fluorescence. The median widths of fluorescence from the tumor edge in HCC and CRLM were 1227.5 μm and 1608 μm, respectively, with no significant difference. Conclusion Near-infrared fluorescent imaging can reliably detect safe surgical margins intraoperatively during liver resection.

Three-dimensional virtual endoscopy (3DVE) has the potential advantage of enhanced anatomic delineation and spatial orientation during laparoscopic procedures. In the present study, we aimed to evaluate the impact of 3DVE guidance in laparoscopic distal pancreatectomy (LDP). Thirty-eight patients presenting to our hospital with a variety of pancreatic tumors underwent preoperative computed tomography scanning to clearly define the major peripancreatic vasculature and correlate it with a 3DVE system (SYNAPSE VINCENT: Fujifilm Medical, Tokyo, Japan). This map served as the guide during preoperative planning, surgical education, and simulation and as intraoperative navigation reference for LDP. Operative records and pathological findings were analyzed for each procedure. Operative parameters were compared between the 38 patients in this study and 8 patients performed without 3DVE guidance at our institution. The 3DVE navigation system successfully created a preoperative resection map in all patients. Relevant peripancreatic vasculature displayed on the system was identified and compared during the intervention. The mean blood loss in LDP performed under 3DVE guidance versus LDP without 3DVE was 168.5 +/- 347.6 g versus 330.0 +/- 211.4 g, p = 0.008 while and the operative time was 171.9 +/- 51.7 min versus 240.6 +/- 24.8 min, p = 0.001. 3DVE in conjunction with a “laparoscopic eye” creates a preoperative and intraoperative three-dimensional data platform that potentially enhances the accuracy and safety of LDP.

Schwannomas occurring in the hepatoduodenal ligament are extremely rare, with only four cases reported. Here, we describe a case of a 30-mm schwannoma that originated in the hepatoduodenal ligament of a 38-year-old female found during a periodic medical check-up. Magnetic resonance imaging demonstrated a tumor in the hepatoduodenal ligament. Following an ultrasound-guided microbiopsy, histological examination showed solitary fibrous tumor or schwannomas in the liver or originating from the hepαtoduodenal ligament. The relationship between the tumor and associated organs was confirmed intraoperatively, and the tumor was removed safely in its entirety using indocyanine green. The postoperative histopathological examination revealed the presence of a schwannoma with typical characteristics. To our knowledge, this is the first case of hepatoduodenal ligament schwannoma treated by laparoscopic surgery using indocyanine green fluorescence imaging.

Radiofrequency ablation (RFA) is used to treat primary and metastatic tumors in the liver. However, local recurrence after RFA is frequent and subsequent salvage hepatectomy is often ineffective due to difficulty in visualization of tumor margins.In the present retrospective clinical trial, seven patients from the Department of General and Gastro-enterological Surgery, Showa University School of Medicine underwent salvage hepatectomy for recurrent hepatocellular carcinoma (HCC) (n=2), colorectal liver metastasis (n=4) and lung-carcinoid liver metastasis (n=1), after RFA, between 2011 and 2020. Tumors were labeled with indocyanine green (ICG) and resected under fluorescence guidance. Resected specimens were evaluated under fluorescence microscopy as well as by standard histopathological techniques.Pathological findings revealed negative tumor margins in all patients after fluorescence-guided surgery. Six of seven resected tumors had a fluorescent rim, including both HCC and liver metastasis. Fluorescence microscopy demonstrated that viable cancer tumor cells were located only on the inside of the fluorescent rim, and no malignant cells were detected within the fluorescent rim surrounding the tumor. Fluorescence microscopy showed that the tumor margin was secured if the fluorescence signal was completely resected.The present results demonstrate that ICG labeling of liver tumors recurring after RFA enabled complete resection under fluorescence guidance. The present study is the first clinical study to demonstrate that tumor types that generally cannot be completely resected with bright light are fully resectable under fluorescence guidance.

Probe-based confocal laser endomicroscopy (pCLE) can visualize microscopic structures at high resolution but has not yet yielded definitive diagnostic features of gallbladder malignancy, as opposed to benign changes.A total of 73 patients had their gallbladder evaluated with pCLE performed on resected benign and malignant gallbladder surgical specimens, which were sprayed with fluorescein. Malignant and benign features of pCLE findings were identified on the basis of Miami and Paris Classifications. Standard histopathological diagnoses and individual patient pCLE findings of gallbladder lesions were correlated.Of the 73 consecutive patients that had their gallbladder evaluated ex vivo with pCLE, 11 were identified with gallbladder malignancy. pCLE identified features of gallbladders examined ex vivo, including the presence of thick dark bands and dark clumps, which together correlated with histopathologically-determined biliary malignancy at 100% sensitivity. Thick white bands and visualized epithelium, also identified with pCLE, together correlated with histopathologically-determined malignancy at 100% specificity.pCLE can be used for real-time differentiation of cancerous/non-cancerous regions in the gallbladder using the diagnostic criteria identified in the present study.

Hideki Shibata, Takeshi Aoki, Tomotake Koizumi, Tomokazu Kusano, Tatsuya Yamazaki, Kazuhiko Saito, Takahito Hirai, Kodai Tomioka, Yusuke Wada, Tomoki Hakozaki, Yoshihiko Tashiro, Koji Nogaki, Kosuke Yamada, Kazuhiro Matsuda, Akira Fujimori, Yuta Enami, Masahiko Murakami Division of Gastroenterological and General Surgery, Department of Surgery, School of Medicine, Showa University, Tokyo, JapanCorrespondence: Takeshi AokiDivision of Gastroenterological and General Surgery, Department of Surgery, School of Medicine, Showa University, 1-5-8, Hatanodai, Shinagawa-Ku, Tokyo, 142-8555, JapanTel +81-3-3784-8000Fax +81-3-3784-5835Email takejp@med.showa-u.ac.jpPurpose: Bile duct injury is one of the most serious complications of laparoscopic cholecystectomy. Intraoperative indocyanine green (ICG) cholangiography is a safe and useful navigation modality for confirming the biliary anatomy. ICG cholangiography is expected to be a routine method for helping avoid bile duct injuries.Patients and Methods: We examined 25 patients who underwent intraoperative cholangiography using ICG fluorescence. Two methods of ICG injection are used: intrabiliary injection (percutaneous transhepatic gallbladder drainage [PTGBD], gallbladder [GB] puncture and endoscopic nasobiliary drainage [ENBD]) at a dosage of 0.025 mg during the operation or intravenous injection with 2.5 mg ICG preoperatively.Results: There were 24 patients who underwent laparoscopic cholecystectomy and 1 patient who underwent hepatectomy. For laparoscopic cholecystectomy, the average operation time was 127 (50– 197) minutes, and estimated blood loss was 43.2 (0– 400) g. The ICG administration route was intravenous injections in 12 cases and intrabiliary injection in 12 cases (GB injection: 3 cases, PTGBD: 8 cases, ENBD:1 case). The course of the biliary tree was able to be confirmed in all cases that received direct injection into the biliary tract, whereas bile structures were recognizable in only 10 cases (83.3%) with intravenous injection. The postoperative hospital stay was 4.6 (3– 9) days, and no postoperative complications (Clavien–Dindo ≧IIIa) were observed. For hepatectomy, a tumor located near the left Glissonian pedicle was resected using a fluorescence image guide. Biliary structures were fluorescent without injury after resecting the tumor. No adverse events due to ICG administration were observed, and the procedure was able to be performed safely.Conclusion: ICG fluorescence imaging allows surgeons to visualize the course of the biliary tree in real time during cholecystectomy and hepatectomy. This is considered essential for hepatobiliary surgery to prevent biliary tree injury and ensure safe surgery.Keywords: indocyanine green fluorescent imaging, navigation surgery, near-infrared fluorescent cholangiography

Obesity is a positive predictor of surgical morbidity. There are few reports of laparoscopic cholecystectomy (LC) outcomes in obese patients. This study aimed to clarify this relationship. This retrospective study included patients who underwent LC at Showa University Northern Yokohama Hospital between January 2017 and April 2020. A total of 563 cases were examined and divided into two groups: obese (n = 142) (BMI ≥ 25 kg/m2) and non-obese (n = 241) (BMI 2). The non-obese group had more female patients (54%), whereas the obese group had more male patients (59.1%). The obese group was younger (56.6 years). Preoperative laboratory data of liver function were within the normal range. The obese group had a significantly higher white blood cell (WBC) count (6420/μL), although this was within normal range. Operative time was significantly longer in the obese group (p = 0.0001). However, blood loss and conversion rate were not significantly different among the groups, neither were surgical outcomes, including postoperative hospital stay and complications. Male sex and previous abdominal surgery were risk factors for conversion, and only advanced age (≥ 79 years) was an independent predictor of postoperative complications as observed in the multivariate analysis. Although the operation time was prolonged in obese patients, operative factors and outcomes were not. Therefore, LC could be safely performed in obese patients with similar efficacy as in non-obese patients.

Recently, virtual navigation system has been applied to hepatic surgery, enabling better visualization of intrahepatic vascular branches and location of tumor. Intraoperative ultrasonography (IOUS) is the most common form of image guidance during liver surgery. However, during laparoscopic hepatectomies (LH), IOUS has several limitations and its reliability has been poorly evaluated. The objective of this work is to evaluate VRCT (virtual real-time CT-guided volume navigation) during LH. This system aims to provide accurate anatomical orientation for surgeons enhancing the safety of LH.Twenty-seven hepatic neoplasms were resected laparoscopically at our institution under reference guidance of VRCT. During operation, electromagnetic tracking of the surgical instrument was used for navigating the direction of accurate liver transection.Twenty-six (96.3%) of the 27 lesions (mean diameter 11 mm) were successfully performed under VRCT guidance. Average registration time was 2 min. Average setup time was approximately 7 min per procedure. VRCT allows the surgeon to navigate liver transection with acceptable accuracy. The mean error was 12 mm. All surgical margins were negative and the mean histologic resection margin was 9 mm.VRCT-guided LH is feasible and provides valuable real-time anatomical feedback during hepatic resections. Advancement of such systems to improve accuracy might greatly compensate for the limitation of laparoscopic IOUS.

Background Pancreatic fistula is one of the serious complications for patients undergoing distal pancreatectomy, which leads to significant morbidity. The aim of our study is to compare linear stapling closure plus continuous suture with linear stapling closure alone during laparoscopic distal pancreatectomy (LDP) in terms of clinically relevant postoperative pancreatic fistula (POPF) rate. Methods Twenty-two patients underwent LDP at our institution between 2011 and 2013. Twelve patients had linear stapling closure with peri-firing compression (LSC) alone compared with ten patients who had linear stapling closure, peri-firing compression plus continuous suture (LSC/CS) for stump closure of remnant pancreas in LDP. Biochemical leak and clinically relevant POPF were compared between both groups. Results POPF occurred in 4 of 12 (33.3%) patients with linear stapling closure while no patient developed a clinically relevant POPF in the triple combination of linear stapling, peri-firing compression plus continuous suture group (p = 0.043).1 patient (8.3%) in the LSC group and 5 patients (50%) in the LSC/CS group had evidence of a biochemical leak. There were no significant differences in operative time (188.3 vs 187.0 min) and blood loss (135 vs. 240 g) between both groups but there was a significantly of shorter length of hospital stay (11.9 vs. 19.9 days) in LSC/CS group (p = 0.037). There was no mortality in either group. Conclusions The triple combination of linear stapling, peri-firing compression plus continuous suture in LDP has effectively prevented occurrence of clinically relevant ISGPF POPF. Trial registration The study was retrospectively registered September 30, 2019 at Showa University Ethics Committee as IRB protocol numbers 2943.

Solid pseudopapillary neoplasm (SPN) of the pancreas has generally been regarded as a low-grade malignant tumour that preferentially develops in young women and can have a good prognosis with surgery. Among the few patients who have died from metastatic SPN are mostly those whose tumours harbour an undifferentiated component characterized by diffuse sheets of cells with increased nuclear atypia and proliferative index. We herein report a case of an aggressive, fatal, solid pseudopapillary neoplasm (SPN) of the pancreas in a 63-year-old woman complaining of epigastric pain. Despite having undergone surgical resection for a 10 cm pancreatic mass and multiple liver metastases, the patient later died due to uncontrollable metastases 36 months after the initial surgery. Histological examination showed that the tumour displayed unusual high-grade malignant features, showing diffuse sheets of cells with increased nuclear atypia and proliferative activity, along with conventional low-grade malignant features. The tumour was subsequently recognized as an SPN with foci of high-grade malignant transformation according to the 2010 World Health Organization classification. Immunohistochemical studies revealed that p16-RB pathway alterations contributed to the high-grade malignant transformation. The present case report suggests the necessity for developing diagnostic and treatment methods targeting p16 and RB for high-grade variants of SPN.

Associations have been made between maternal selective serotonin reuptake inhibitor (SSRI) use during pregnancy and altered behavior in offspring, including an increased risk of autism. Given the important role serotonin plays in behavior, we hypothesized SSRI exposure in the perinatal period would alter central serotonin receptor expression and program adult behaviors in mice.Female mice were injected with sertraline or saline throughout pregnancy. Offspring continued to receive injections on postnatal days 1-14, a time period in mice similar to the third trimester in human pregnancy. Adult offspring underwent behavioral testing, and serotonin receptor mRNA levels were quantified.Compared to controls, SSRI exposed mice did not have a reduction in social interactions, spatial learning, or exploratory behavior. As adults, sertraline exposed mice had significantly increased mRNA levels of multiple 5-HT receptors, serotonin transporter (5-HTT), and tryptophan hydroxylase isoform 2 in the cerebral cortex.Although no behavioral phenotype was observed, SSRI exposure in the perinatal period permanently alters cerebral receptor mRNA levels. We speculate these shifts in mRNA expression provide important compensation during SSRI exposure. Further pre-clinical and clinical investigation into additional serotonin-regulated phenotypes is necessary to further assess the long-term implications of perinatal SSRI exposure.

OTC drugs have an important role in self-medication. However, the pharmacokinetic properties of some OTC drugs have not been fully investigated and reports concerning their drug interactions are insufficient. Several gastrointestinal drugs are available as OTC drugs. Because of their pharmacological properties, these drugs are often used concomitantly with other drugs. Therefore, it is important to predict the possible drug interactions among these drugs. In the current study, we investigated the inhibitory effects of five gastrointestinal drugs, namely loperamide, oxethazaine, papaverine, pirenzepine, and trimebutine, on CYP activities in human liver microsomes. Furthermore, we calculated the ratio of the intrinsic clearance of each CYP substrate in the presence or absence of the gastrointestinal drugs. The possibility of drug interactions in vivo was predicted by cut-off criteria. CYP3A4 activity was markedly inhibited by trimebutine, papaverine, and oxethazaine. Their inhibitory properties were competitive and the Ki values were 6.56, 12.8, and 3.08 µM, respectively. Alternative R values of CYP3A4 exceeded the cut-off level. These results suggested that drug interactions mediated by CYP3A4 may occur during treatment with these gastrointestinal drugs, necessitating the confirmation of the clinical significance of these drug interactions to prevent unexpected adverse effects.

There have been few reports concerning to the drug-drug interactions (DDIs) with OTC drugs although an increase in the use of OTC drugs in recent years. This current study was conducted to clarify the DDIs through CYP3A inhibition by oxethazaine (OXZ), an antacid available as an OTC drug. Midazolam (MDZ) was used as a probe drug for CYP3A activity. In an in vivo study, a single oral dose of OXZ (50 mg/kg) was administered to rats 30, 60, or 120 min before oral MDZ administration (15 mg/kg). Serum concentrations of MDZ were analyzed by HPLC, and its pharmacokinetic parameters were compared with a water-treated control group. The inhibitory effect of OXZ on MDZ 1'-hydroxylation (MDZ 1'-OH) activity was investigated in vitro using rat liver and intestinal microsomes. Pretreatment of OXZ 120 min before MDZ administration significantly increased the area under the serum concentration-time curve (AUC0-∞) of MDZ six-fold compared to the control group without a change in elimination half-life (t1/2). In contrast, OXZ pretreatment 30 or 60 min before MDZ administration did not show any remarkable change in MDZ pharmacokinetic parameters. The in vitro study showed that OXZ inhibited MDZ 1'-OH activity in a concentration-dependent manner both in liver and intestinal microsomes. These results suggested that OXZ increases serum MDZ concentration presumably by the inhibition of liver and/or intestinal CYP3A activity. OXZ was predicted to cause the DDIs mediated by CYP3A inhibition, although this effect depended on the dose interval.

Hepatobiliary and pancreatic surgery is recognized as technically demanding due to the complicated local anatomy and diverse anatomical variation that require precise techniques. Therefore, preoperative simulation to understand the detailed local anatomy and intraoperative navigation methods for surgical guidance are needed. Intraoperative navigation for anatomical hepatectomy originated with dye injection into the dominant portal pedicle under intraoperative ultrasound guidance to identify hepatic segments, which was reported by Makuuchi et al in 1985. In recent years, with advancing medical technology, newer medical devices that promote the safety and reliability of various surgical procedures have been developed. In this article, we will discuss the current state and future prospects of intraoperative navigation in hepatobiliary and pancreatic surgery.

Background/aim Benifuuki tea has recently been used as an alternative therapy for pollinosis, and it may be consumed with pharmaceutical drugs. This study aimed to examine cytochrome P450 (CYP)-mediated food-drug interactions with Benifuuki tea in rats. Materials and methods The inhibitory effects of Benifuuki tea and (-)-epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me) on CYP activities were evaluated in vitro. Midazolam pharmacokinetics was investigated after two treatments with Benifuuki tea. In an ex vivo study, CYP activities were determined after 1-week-treatment with the tea. Results Benifuuki tea and EGCG3"Me inhibited CYP2D and CYP3A activities in a concentration-dependent manner in vitro. However, MDZ metabolism did not change by Benifuuki treatment in vivo and ex vivo. In contrast, CYP2D activity was decreased ex vivo. Conclusion Normal intake of Benifuuki tea is not likely to cause food-drug interactions by CYP3A inhibition or induction. In contrast, Benifuuki tea consumption may lead to food-drug interactions through the inhibition of CYP2D.

A 37-year-old Nepalese man was admitted to Showa University Hospital because of a loss of consciousness and seizures. He had lived in Nepal, Qatar, Singapore, and India before the age of 34 years. He had no history of having eaten raw pork. His physical findings were normal excluding an abnormal visual field, and a positive serum antibody test result for Taenia solium, CT and MRI examinations showed multiple nodular lesions in his brain and thigh. We resected a cyst from his left thigh and diagnosed him as having cysticercosis based on the presence of characteristic hooklets and suckers on a pathological examination. Later, the Asian type of Cysticercus cellulosa was identified using a mitochondrial DNA test. Albendazole (800 mg/day) and prednisolone (60 mg/day) were administered for 14 days. All cysticercus were smaller on Day7 and had almost disappeared on Day 14. No adverse effects from the treatment occurred. Cysticercosis is rare in Japan, and cases requiring treatment for a large number of cysticercus in the brain and thigh are rare. We report a case of neurocysticercosis that had a good clinical course.

In this paper, a modeling method of human actions is proposed in order to realize such systems as to assist human operations have been desired, which must have a certain human action model to recognize or support various kinds of human actions. In the proposed method, a human action model is extracted statistically from enormous data obtained by long-term observation of human actions with sensors, which means only frequent human actions are modeled in this method. In addition, the human action model obtained by the proposed method has high readability, which makes human action analysis much easier. In order to generate a human action model with the previous two features, a human action and a situation around a person are modeled as time series data expressed by Hidden Markov Model(HMM). This is because HMM can efficiently model a time series data with temporal and spatial redundancy. In addition, the relationship between a situation and a human action modeled by HMMs is expressed by If-Then-Rule style explicitly.

Recently, systems to support or recognize human actions have been desired, which must have a certain human action model. Based on this reason, a new modeling method of human actions is proposed in this paper. In the proposed method, a human action model is statistically generated by extraction from enormous data on human actions obtained by long-term monitoring with sensors. Therefore, human actions can be modeled without previous knowledge. In addition, a human action model is generated considering the significance of the differences of not only spatial patterns but also temporal ones on human actions. In the proposed method, a Hidden Markov Model (HMM) and a Hidden Semi Markov Model (HSMM) are properly used to express a human action pattern depending on applications. This is because the amount of the significance of the temporal difference is different depending on the purpose of the use of the human action model. In addition, the relationship between the situation and a human action is expressed by a If-Then-Rule style explicitly. Therefore, an obtained human action model has high readability.