Risk factors for post-colorectal endoscopic submucosal dissection bleeding and efficacy of carbazochrome sodium sulfonate: A multicenter retrospective cohort study.

BACKGROUND: Carbazochrome sodium sulfonate (CSS) is a hemostatic agent that reduces capillary permeability and enhances capillary resistance. However, its specific effects on colorectal endoscopic submucosal dissection (ESD) outcomes remain uncertain. This study aimed to assess the risk factors for post-ESD bleeding and the effect of CSS on colorectal ESD outcomes. METHODS: First, we retrospectively analyzed the risk factors for post-ESD bleeding using data from 1,315 lesions in 1,223 patients who underwent ESD for superficial colorectal neoplasms at eight institutions. Second, patients were divided into CSS and non-CSS groups using propensity score matching, and their outcomes from colorectal ESD were analyzed. RESULTS: The risk factors for post-colorectal ESD bleeding were identified as age of ≥70 years, tumor located in the rectum, tumor size of ≥40 mm, and post-ESD defect unclosure in both univariate and multivariate analyses. The CSS and non-CSS groups each consisted of 423 lesions after propensity score matching. The post-colorectal ESD bleeding rate was 3.5% (15/423) and 3.3% (14/423) in the CSS and non-CSS groups, respectively, indicating no significant differences. Among patients with the high-risk factors for post-ESD bleeding, the administration of CSS also did not demonstrate a significant reduction in the post-ESD bleeding rate compared to the non-CSS group. CONCLUSIONS: CSS administration is ineffective in preventing post-colorectal ESD bleeding in both the general population and individuals at a high risk for such bleeding. Our results indicate the necessity to reconsider the application of CSS for preventing post-colorectal ESD bleeding.

Approach/Avoidance Behavior to Novel Objects is Correlated with the Serotonergic and Dopaminergic Systems in the Brown Rat (Rattus norvegicus).

The brown rat (Rattus norvegicus) is known to show three types of behavioral responses to novel objects. Whereas some rats are indifferent to novel objects, neophobic and neophilic rats show avoidance and approach behavior, respectively. Here, we compared the dopaminergic, serotonergic, and noradrenergic systems immunohistochemically among these rats. Trapped wild rats and laboratory rats were first individually exposed to the novel objects in their home cage. Wild rats were divided into neophobic and indifferent rats depending on their behavioral responses. Similarly, laboratory rats were divided into neophilic and indifferent rats. Consistent with the behavioral differences, in the paraventricular nucleus of the hypothalamus, Fos expression in corticotropin-releasing hormone-containing neurons was higher in the neophobic rats than in the indifferent rats. In the anterior basal amygdala, the neophobic rats showed higher Fos expression than the indifferent rats. In the posterior basal amygdala, the neophobic and neophilic rats showed lower and higher Fos expressions than the indifferent rats, respectively. When we compared the neuromodulatory systems, in the dorsal raphe, the number of serotonergic neurons and Fos expression in serotonergic neurons increased linearly from neophobic to indifferent to neophilic rats. In the ventral tegmental area, Fos expression in dopaminergic neurons was higher in the neophilic rats than in the indifferent rats. These results demonstrate that approach/avoidance behavior to novel objects is correlated with the serotonergic and dopaminergic systems in the brown rat. We propose that the serotonergic system suppresses avoidance behavior while the dopaminergic system enhances approach behavior to novel objects.

Sensitivity assessment of diphacinone by pharmacokinetic analysis in invasive black rats in the Bonin (Ogasawara) Archipelago, Japan.

The Bonin Archipelago is a United Nations Educational, Scientific and Cultural Organization's World Natural Heritage Site in Japan with a unique ecosystem; however, the invasive rodents preying on endemic species have been a significant concern. The anticoagulant rodenticide, diphacinone, sprayed by the Ministry of the Environment, has succeeded; however, its repeated use leads to rodenticide resistance. This study evaluated the sensitivity by in vivo pharmacokinetics/pharmacodynamics (PK/PD) analysis and physiologically-based pharmacokinetic modeling to diphacinone in black rats (Rattus rattus) captured on the Bonin Archipelago in February 2022. The Bonin rats exhibited prolonged coagulation time after diphacinone administration. They recovered earlier than susceptible black rats, indicating that Bonin rats were less susceptible, though there were no genetic mutations in Vkorc1, the target enzyme of diphacinone. After the administration of diphacinone, hepatic expression levels of Fsp1, identified as the vitamin K reductase, was decreased, however, the Bonin rats exhibited the most minor suppression. The PK analysis showed that the excretion capacity of the Bonin rats was lower than that of the resistant black rats. In the PBPK modeling, the resistant black rats showed higher clearance than the Bonin and susceptible black rats due to high hepatic metabolic capacity. The Bonin rats demonstrated slow absorption and relatively low clearance. This study highlighted the reduced rodenticide-sensitive tendency of wild black rats in the Bonin Archipelago at an in vivo phenotype level. At the same time, they do not have known rodenticide resistance mechanisms, such as hepatic metabolic enhancement or Vkorc1 mutations. It is crucial to monitor the biological levels to evaluate rodenticide sensitivity accurately.

Pesticide Contamination Levels in the Stomach Contents of Wild Raccoons (Procyon lotor) and Masked Palm Civets (Paguma larvata) in Japan.

Pesticides, which are vital for agriculture, pose a significant threat to wildlife in transformed Japanese landscapes. Despite global reports of pesticide poisoning in animals, limited studies have examined current wildlife exposure in croplands or metropolitan areas in the region. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS), our study aimed to assess the contamination status of 368 commonly used pesticides. The stomach contents of raccoons living in croplands contained 13 pesticides, including six herbicides and 11 fungicides. Neonicotinoid insecticides, some fungicides, and previously banned insecticides (benzene hexachloride and dichlofenthion) were most frequently detected and found at the highest concentrations, suggesting direct soil-plant transfer and direct consumption by crop-eating species. In masked palm civets living in metropolitan areas, four insecticides and six fungicides were detected, indicating urban wildlife exposure from raided dustbins, urban gardens, and lumber from houses. Although the maximum measured concentrations of all pesticides were lower than the acceptable daily intake for humans, it remains unclear whether these concentrations may have toxic or adverse health effects on the species evaluated in these transformed landscapes. Our study is the first to examine recent pesticide exposures in wild mammals in Japan. Application of the method we developed will lay the foundation for the examination of pesticides in other wildlife species to assist conservation management efforts in the region. Environ Toxicol Chem 2024;43:943-951. © 2024 SETAC.

Background factors of idiopathic peptic ulcers and optimal treatment methods: a multicenter retrospective Japanese study.

This study investigated the trends in idiopathic peptic ulcers, examined the characteristics of refractory idiopathic peptic ulcer, and identified the optimal treatment. The characteristics of 309 patients with idiopathic peptic ulcer were examined. We allocated idiopathic peptic ulcers that did not heal after 8 weeks' treatment (6 weeks for duodenal ulcers) to the refractory group and those that healed within this period to the healed group. The typical risk factors for idiopathic peptic ulcer (atherosclerosis-related underlying disease or liver cirrhosis complications) were absent in 46.6% of patients. Absence of gastric mucosal atrophy (refractory group: 51.4%, healed group: 28.4%; p = 0.016), and gastric fundic gland polyps (refractory group: 17.6%, healed group: 5.9%; p = 0.045) were significantly more common in the refractory group compared to the healed group. A history of H. pylori eradication (refractory group: 85.3%, healed group: 66.0%; p = 0.016), previous H. pylori infection (i.e., gastric mucosal atrophy or history of H. pylori eradication) (refractory group: 48.5%, healed group: 80.0%; p = 0.001), and potassium-competitive acid blocker treatment (refractory group: 28.6%, healed group, 64.1%; p = 0.001) were significantly more frequent in the healed group compared to the refractory group. Thus, acid hypersecretion may be a major factor underlying the refractoriness of idiopathic peptic ulcer.

The clinical efficacy and safety of granulocyte and monocyte adsorptive apheresis in patients with Crohn's disease: A multicenter retrospective pilot study.

INTRODUCTION: A remission induction therapy of granulocyte and monocyte adsorptive apheresis (GMA) was given to patients with Crohn's disease (CD). However, establishing an appropriate treatment strategy for GMA in patients with CD remains unclear. METHODS: This study evaluated the clinical efficacy and subsequent clinical progression after GMA in patients with CD who underwent GMA in seven independent institutions in Japan from 2010 to 2023. RESULTS: Sixteen patients were enrolled. The overall remission and response rates were 25.0% and 68.8%, respectively. All patients responding to GMA received biologics that were continuously used and 36.4% of patients remained on the same biologics 52 weeks after GMA. Notably, all patients who continued the same biologics had previously experienced a loss of response to biologics. CONCLUSION: GMA may exhibit effectiveness even in cases with refractory CD. Moreover, it represents a potential novel therapeutic option for refractory CD with loss of response to biologics.

[The task of the medical cooperation system for patients with inflammatory bowel disease in the northern and eastern regions of Hokkaido].

In Japan, establishing a medical cooperation system for patients with inflammatory bowel disease (IBD) between IBD flagship and local care hospitals is a crucial task. Thus, this retrospective multicenter cohort study aims to examine the actual state of medical treatment in patients with IBD via a questionnaire survey administered to eight dependent institutes in Hokkaido, Japan. The present results clarified the clinical disparities of IBD treatment and hospital function between IBD flagship hospitals and local care hospitals. Moreover, the understanding level of IBD treatment in medical staff was significantly lower in local care than in IBD flagship hospitals. Furthermore, an abounding experience of IBD treatment affected the understanding level of IBD treatment of both medical doctors and staff. These findings indicate that selecting patients with IBD corresponding to disease activity, educational system for the current IBD treatment, and promotion of team medicine with multimedical staff can resolve clinical discrepancies between IBD flagship and local care hospitals. The IBD treatment inequities in Japan will be eliminated with the development of an appropriate medical cooperation system between IBD flagship and local care hospitals.

Beat-wise segmentation of electrocardiogram using adaptive windowing and deep neural network.

Timely detection of anomalies and automatic interpretation of an electrocardiogram (ECG) play a crucial role in many healthcare applications, such as patient monitoring and post treatments. Beat-wise segmentation is one of the essential steps in ensuring the confidence and fidelity of many automatic ECG classification methods. In this sense, we present a reliable ECG beat segmentation technique using a CNN model with an adaptive windowing algorithm. The proposed adaptive windowing algorithm can recognise cardiac cycle events and perform segmentation, including regular and irregular beats from an ECG signal with satisfactorily accurate boundaries.The proposed algorithm was evaluated quantitatively and qualitatively based on the annotations provided with the datasets and beat-wise manual inspection. The algorithm performed satisfactorily well for the MIT-BIH dataset with a 99.08% accuracy and a 99.08% of F1-score in detecting heartbeats along with a 99.25% of accuracy in determining correct boundaries. The proposed method successfully detected heartbeats from the European S-T database with a 98.3% accuracy and 97.4% precision. The algorithm showed 99.4% of accuracy and precision for Fantasia database. In summary, the algorithm's overall performance on these three datasets suggests a high possibility of applying this algorithm in various applications in ECG analysis, including clinical applications with greater confidence.

Concomitant pharmacologic medications influence the clinical outcomes of granulocyte and monocyte adsorptive apheresis in patients with ulcerative colitis: A multicenter retrospective cohort study.

BACKGROUND: Granulocyte and monocyte adsorptive apheresis (GMA) with Adacolumn has been used as a remission induction therapy for patients with active ulcerative colitis (UC). Herein, we investigated the influence of concomitant medications in the remission induction of GMA in patients with active UC. METHODS: This multicenter retrospective cohort study included patients with UC underwent GMA in five independent institutions in Japan from January 2011 to July 2021. Factors including concomitant medications associated with clinical remission (CR) were analyzed statistically. RESULT: A total of 133 patients were included. Seventy-four patients achieved a CR after GMA. The multivariable analysis revealed that concomitant medication with 5-aminosalicylic acid, Mayo endoscopic subscore (MES), and concomitant medication with immunosuppressors (IMs) remained as predictors of CR after GMA. In the subgroup analysis in patients with MES of 2, concomitant medication with IMs was demonstrated as a significant negative factor of CR after GMA (P = .042, OR 0.354). Seventy-four patients who achieved CR after GMA were followed up for 52 weeks. In the multivariable analysis, the maintenance therapy with IMs was demonstrated as a significant positive factor of sustained CR up to 52 weeks (P = .038, OR 2.214). Furthermore, the rate of sustained CR in patients with biologics and IMs was significantly higher than that in patients with biologics only (P = .002). CONCLUSION: GMA was more effective for patients with active UC that relapsed under treatment without IMs. Furthermore, the addition of IMs should be considered in patients on maintenance therapy with biologics after GMA.

Travel time optimization on multi-AGV routing by reverse annealing.

Quantum annealing has been actively researched since D-Wave Systems produced the first commercial machine in 2011. Controlling a large fleet of automated guided vehicles is one of the real-world applications utilizing quantum annealing. In this study, we propose a formulation to control the traveling routes to minimize the travel time. We validate our formulation through simulation in a virtual plant and authenticate the effectiveness for faster distribution compared to a greedy algorithm that does not consider the overall detour distance. Furthermore, we utilize reverse annealing to maximize the advantage of the D-Wave's quantum annealer. Starting from relatively good solutions obtained by a fast greedy algorithm, reverse annealing searches for better solutions around them. Our reverse annealing method improves the performance compared to standard quantum annealing alone and performs up to 10 times faster than a commercial classical solver, Gurobi. This study extends a use of optimization with general problem solvers in the application of multi-AGV systems and reveals the potential of reverse annealing as an optimizer.

Prognostic factors to predict the survival in patients with advanced gastric cancer who receive later-line nivolumab monotherapy-The Asahikawa Gastric Cancer Cohort Study (AGCC).

BACKGROUND: Chemotherapy for advanced gastric cancer is recommended in the guidelines; however, later-line treatment remains controversial. Since immune checkpoint inhibitors have been used for the treatment of various malignancies, trials have been performed for gastric cancer. A phase 3 trial indicated the survival benefit of nivolumab monotherapy for gastric cancer patients treated with prior chemotherapy regimens. PATIENTS AND METHODS: A regional cohort study was undertaken to determine the real-world data of nivolumab treatment for patients with advanced or recurrent gastric cancer. The patients were enrolled for 2 years from October 2017 to October 2019 and were prospectively followed for 1 year to examine the overall survival (OS). The patient characteristics were analyzed in a multivariate analysis and a nomogram to predict the probability of survival was generated. RESULTS: In total, 70 patients who received nivolumab as ≥third-line chemotherapy were included in the Asahikawa Gastric Cancer Cohort. The median OS was 7.5 (95% CI, 4.8-10.2) months and the response rate was 18.6%. Diffuse type classification, bone metastasis, high neutrophil/lymphocyte ratio, and high CRP were associated with poor OS/prognosis in the multivariate analysis. A nomogram was developed based on these clinical parameters and the concordance index was 0.80 (95% CI, 0.68-0.91). The responders were aged and were frequently diagnosed with intestinal type gastric cancer, including patients with a HER2-positive status (27.3%) or microsatellite instability-high (27.3%) status. CONCLUSIONS: The regional cohort study of nivolumab monotherapy for gastric cancer patients revealed prognostic factors and a nomogram was developed that could predict the probability of survival.

Fecal calprotectin is a useful biomarker for predicting the clinical outcome of granulocyte and monocyte adsorptive apheresis in ulcerative colitis patients: a prospective observation study.

BACKGROUND: Granulocyte and monocyte adsorptive apheresis (GMA) is widely used as a remission induction therapy for active ulcerative colitis (UC) patients. However, there are no available biomarkers for predicting the clinical outcome of GMA. We investigated the utility of Fecal calprotectin (FC) as a biomarker for predicting the clinical outcome during GMA therapy in active UC patients. METHODS: In this multicenter prospective observation study, all patients received 10 sessions of GMA, twice a week, for 5 consecutive weeks. FC was measured at entry, one week, two weeks, and at the end of GMA. Colonoscopy was performed at entry and after GMA. The clinical activity was assessed based on the partial Mayo score when FC was measured. Clinical remission (CR) was defined as a partial Mayo score of ≤ 2 and endoscopic remission (ER) was defined as Mayo endoscopic subscore of either 0 or 1. We analyzed the relationships between the clinical outcome (CR and ER) and the change in FC concentration. RESULT: Twenty-six patients were included in this study. The overall CR and ER rates were 50.0% and 19.2%, respectively. After GMA, the median FC concentration in patients with ER was significantly lower than that in patients without ER (469 mg/kg vs. 3107 mg/kg, p = 0.03). When the cut-off value of FC concentration was set at 1150 mg/kg for assessing ER after GMA, the sensitivity and specificity were 0.8 and 0.81, respectively. The FC concentration had significantly decreased by one week. An ROC analysis demonstrated that the reduction rate of FC (ΔFC) at 1 week was the most accurate predictor of CR at the end of GMA (AUC = 0.852, P = 0.002). When the cut-off value of ΔFC was set at ≤ 40% at 1 week for predicting CR at the end of GMA, the sensitivity and specificity were 76.9% and 84.6%, respectively. CONCLUSION: We evaluated the utility of FC as a biomarker for assessing ER after GMA and predicting CR in the early phase during GMA in patients with active UC. Our findings will benefit patients with active UC by allowing them to avoid unnecessary invasive procedures and will help establish new strategies for GMA.

Assessment of image generation by quantum annealer.

Quantum annealing was originally proposed as an approach for solving combinatorial optimization problems using quantum effects. D-Wave Systems has released a production model of quantum annealing hardware. However, the inherent noise and various environmental factors in the hardware hamper the determination of optimal solutions. In addition, the freezing effect in regions with weak quantum fluctuations generates outputs approximately following a Gibbs-Boltzmann distribution at an extremely low temperature. Thus, a quantum annealer may also serve as a fast sampler for the Ising spin-glass problem, and several studies have investigated Boltzmann machine learning using a quantum annealer. Previous developments have focused on comparing the performance in the standard distance of the resulting distributions between conventional methods in classical computers and sampling by a quantum annealer. In this study, we focused on the performance of a quantum annealer as a generative model from a different aspect. To evaluate its performance, we prepared a discriminator given by a neural network trained on an a priori dataset. The evaluation results show a higher performance of quantum annealer compared with the classical approach for Boltzmann machine learning in training of the generative model. However the generation of the data suffers from the remanent quantum fluctuation in the quantum annealer. The quality of the generated images from the quantum annealer gets worse than the ideal case of the quantum annealing and the classical Monte-Carlo sampling.

Safety and efficacy of cold snare polypectomy for small colorectal polyps: A prospective randomized control trial and one-year follow-up study.

TRIAL DESIGN: Elimination of small colorectal polyps with cold snare polypectomy (CSP) is reported to be as safe as hot snare polypectomy (HSP). The effectiveness of CSP has not been clearly defined, and the incidence of long-term recurrence has not been determined. We conducted a randomized control study and one-year follow-up study to assess their safety and efficacy. METHODS: Patients with small colorectal polyps were randomized to receive CSP or HSP. Polypectomy was performed to determine the pathological curability, and patients completed a questionnaire about the tolerability of the procedure. Follow-up colonoscopy was performed to determine the local recurrence of adenoma. The major outcome was the non-inferiority of CSP to HSP in the rate of delayed bleeding and minor outcomes, including the incidence of immediate bleeding and perforation, procedural time, and the resection rate. RESULTS: A total of 119 participants were recruited in this randomized study and underwent polypectomy. Among the 458 polyps, 332 eligible polyps were analyzed. The rate of adverse events was 0.6% (1/175) for CSP and 0% (0/157) for HSP, which showed the non-inferiority of CSP. While the complete resection rate of CSP was very high (100%), the R0 rate was not satisfactory (horizontal margin, 65.5%; vertical margin, 89.1%). Two local recurrences (2.5%) were observed in the follow-up of 80 adenomas treated with CSP. No recurrence was found in 79 lesions in the HSP group, which was not significant (P = .06). CONCLUSIONS: Colorectal polyps were safely resected using CSP, similar to HSP. Most would agree to say that CSP is considered safer than HSP. The main question is then related to efficacy. Our results of the present study demonstrate that recurrence after CSP should be carefully managed for curative treatment.

The VKORC1 ER-luminal loop mutation (Leu76Pro) leads to a significant resistance to warfarin in black rats (Rattus rattus).

Well-known 4-hydroxycoumarin derivatives, such as warfarin, act as inhibitors of the vitamin K epoxide reductase (VKOR) and are used as anticoagulants. Mutations of the VKOR enzyme can lead to resistance to those compounds. This has been a problem in using them as medicine or rodenticide. Most of these mutations lie in the vicinity of potential warfarin-binding sites within the ER-luminal loop structure (Lys30, Phe55) and the transmembrane helix (Tyr138). However, a VKOR mutation found in Tokyo in warfarin-resistant rats does not follow that pattern (Leu76Pro), and its effect on VKOR function and structure remains unclear. We conducted both in vitro kinetic analyses and in silico docking studies to characterize the VKOR mutant. On the one hand, resistant rats (R-rats) showed a 37.5-fold increased IC50 value to warfarin when compared to susceptible rats (S-rats); on the other hand, R-rats showed a 16.5-fold lower basal VKOR activity (Vmax/Km). Docking calculations exhibited that the mutated VKOR of R-rats has a decreased affinity for warfarin. Molecular dynamics simulations further revealed that VKOR-associated warfarin was more exposed to solvents in R-rats and key interactions between Lys30, Phe55, and warfarin were less favored. This study concludes that a single mutation of VKOR at position 76 leads to a significant resistance to warfarin by modifying the types and numbers of intermolecular interactions between the two.

Rare case of fecal impaction caused by a fecalith originating in a large colonic diverticulum: A case report.

BACKGROUND: Fecal impaction is defined as a large mass of compacted feces in the colon and has the potential to induce a serious medical condition in elderly individuals. Fecal impaction is generally preventable, and early recognition of the typical radiological findings is important for making an early diagnosis. The factors that lead to fecal impaction are usually similar to those causing constipation. Few cases with fecal impaction associated with a diverticulum have been reported. CASE SUMMARY: We present the case of a 62-year-old woman who suffered from abdominal pain and vomiting, had a medical history of repeated acute abdomen and was diagnosed with fecal impaction in the descending colon based on X-ray and computed tomography (CT) imaging. After examination by gastrografin-enhanced colonography following colonoscopy and CT colonography, the fecalith was suspected to have been produced at the site of a large diverticulum in the transverse colon. The fecalith was surgically resected, and a histological diagnosis of pseudodiverticulum was made. There was no recurrence during 33 mo of follow-up. CONCLUSION: This case highlights the importance of accurate identification and treatment of a fecal impaction. This case indicated that the endoscopic evacuation and subsequent colonography were effective for identifying a diverticulum that might have caused fecal impaction. A fecal impaction was associated with the diverticulum. Consequently, the planned diverticulectomy was performed. Appropriate emergency medical treatment and maintenance treatments should be selected in such cases to prevent recurrence.

The efficacy of the submucosal injection of lidocaine during endoscopic submucosal dissection for colorectal neoplasms: a multicenter randomized controlled study.

BACKGROUND: Endoscopic submucosal dissection (ESD) is currently a common procedure although it requires a long procedural time. We conducted a prospective study to determine the efficacy and safety of lidocaine injection for shortening the procedural time and relieving bowel peristalsis during ESD. METHODS: A multicenter randomized controlled study was conducted in three hospitals. Ninety-one patients who underwent colorectal ESD were enrolled. Patients were randomly divided into two groups using the envelope method: the lidocaine group and saline group. The primary endpoint was the procedural time, and the secondary endpoints were the procedural time in each part of the colon and the grade of bowel peristalsis and the incidence and amounts of antispasmodic drugs use and adverse events. RESULTS: The patients' demographics were not markedly different between the two groups. The mean procedural time in the lidocaine group was not markedly different from that in the saline group. In contrast, at the proximal site, the procedural time in the lidocaine group (57 min) was significantly shorter in the saline group (80 min). The grade of bowel peristalsis in the lidocaine group (0.67) was significantly lower than in the saline group (1.17). Antispasmodic drug use was significantly rarer in the lidocaine group than in the saline group. The incidence of adverse events was not markedly different between the two groups. CONCLUSIONS: Local lidocaine injection is a feasible option for preventing bowel peristalsis, particularly in the proximal colon, leading to a reduced procedural time for ESD and decreased antispasmodic drug use. University Hospital Medical Information Network Center (UMIN number: 000022843).

Existence of wild brown rats (Rattus norvegicus) that are indifferent to novel objects.

Exposure to novel objects typically evokes avoidance behavior in wild animals, which is called neophobia. We previously found that wild brown rats (Rattus norvegicus) that were trapped in a park in downtown Tokyo, Japan, exhibited neophobia. We also found that this behavior was accompanied by the activation of the basolateral complex of the amygdala (BLA). Previous studies have suggested that genetic factors are the primary determinants of neophobia. Since rats in cities form populations with distinct genetic characteristics, it is reasonable to assume that wild rats caught at different locations in urban centers will exhibit different levels of neophobia. Here we assessed the intensity of neophobia in wild rats trapped at a wholesale market in Tokyo. Although we performed exactly the same experiment in which neophobia was observed in wild rats trapped at the park, the presence of novel objects did not affect the behaviors of wild rats trapped at the market. Conversely, laboratory rats showed approach and exploratory behaviors as seen in the previous study, suggesting that the experiment was performed appropriately. Compared to the laboratory rats, the lack of behavioral changes in the wild rats was accompanied by fewer Fos immunoreactive cells in the BLA. In addition, the numbers of Fos immunoreactive cells in the bed nucleus of the stria terminalis and ventromedial hypothalamus were similar between the two types of rats. The results demonstrated the existence of wild rats that were indifferent to novel objects.

Simple relation between frustration and transition points in diluted spin glasses.

We investigate a possible relation between frustration and phase-transition points in two-dimensional spin glasses at zero temperature. The relation consists of a condition on the average number of frustrated plaquettes and was reported to provide very good predictions for the critical points at zero temperature, for several two-dimensional lattices. Although there has been no proof of the relation, the good correspondence in several lattices suggests the validity of the relation and an important role of frustration in the phase transitions. To examine the relation further, we present a natural extension of the relation to diluted lattices and verify its effectiveness for bond-diluted square lattices. We then confirm that the resulting points are in good agreement with the phase-transition points in a wide range of dilution rate. Our result supports the suggestion from R. Miyazaki [J. Phys. Soc. Jpn. 82, 094001 (2013)JUPSAU0031-901510.7566/JPSJ.82.094001] for nondiluted lattices on the importance of frustration to the phase transition of two-dimensional spin glasses at zero temperature.