Identification of Ppy-lineage cells as a novel origin of pancreatic ductal adenocarcinoma.

The Ppy gene encodes pancreatic polypeptide (PP) secreted by PP- or γ-cells, which are a subtype of endocrine cells localised mainly in the islet periphery. For a detailed characterisation of PP cells, we aimed to establish PP cell lines. To this end, we generated a mouse model harbouring the SV40 large T antigen (TAg) in the Rosa26 locus, which is expressed upon Ppy-promoter-mediated Cre-loxP recombination. Whereas Insulin1-CreERT-mediated TAg expression in beta cells resulted in insulinoma, surprisingly, Ppy-Cre-mediated TAg expression resulted in the malignant transformation of Ppy-lineage cells. These mice showed distorted islet structural integrity at 5 days of age compared with normal islets. CK19+ duct-like lesions contiguous with the islets were observed at 2 weeks of age, and mice developed aggressive pancreatic ductal adenocarcinoma (PDAC) at 4 weeks of age, suggesting that PDAC can originate from the islet/endocrine pancreas. This was unexpected as PDAC is believed to originate from the exocrine pancreas. RNA-sequencing analysis of Ppy-lineage islet cells from 7-day-old TAg+ mice showed a downregulation and an upregulation of endocrine and exocrine genes, respectively, in addition to the upregulation of genes and pathways associated with PDAC. These results suggest that the expression of an oncogene in Ppy-lineage cells induces a switch from endocrine cell fate to PDAC. Our findings demonstrate that Ppy-lineage cells may be an origin of PDAC and may provide novel insights into the pathogenesis of pancreatic cancer, as well as possible therapeutic strategies. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Development of clinical phenotypes and biological profiles via proteomic analysis of trauma patients.

BACKGROUND: Trauma is a heterogeneous condition, and specific clinical phenotypes may identify target populations that could benefit from certain treatment strategies. In this retrospective study, we determined clinical phenotypes and identified new target populations of trauma patients and their treatment strategies. METHODS: We retrospectively analyzed datasets from the Japan Trauma Data Bank and determined trauma death clinical phenotypes using statistical machine learning techniques and evaluation of biological profiles. RESULTS: The analysis included 71,038 blunt trauma patients [median age, 63 (interquartile range [IQR], 40-78) years; 45,479 (64.0%) males; median Injury Severity Score, 13 (IQR, 9-20)], and the derivation and validation cohorts included 42,780 (60.2%) and 28,258 (39.8%) patients, respectively. Of eight derived phenotypes (D-1-D-8), D-8 (n = 2178) had the highest mortality (48.6%) with characteristic severely disturbed consciousness and was further divided into four phenotypes: D-8α, multiple trauma in the young (n = 464); D-8ß, head trauma with lower body temperature (n = 178); D-8γ, severe head injury in the elderly (n = 957); and D-8δ, multiple trauma, with higher predicted mortality than actual mortality (n = 579). Phenotype distributions were comparable in the validation cohort. Biological profile analysis of 90 trauma patients revealed that D-8 exhibited excessive inflammation, including enhanced acute inflammatory response, dysregulated complement activation pathways, and impaired coagulation, including downregulated coagulation and platelet degranulation pathways, compared with other phenotypes. CONCLUSIONS: We identified clinical phenotypes with high mortality, and the evaluation of the molecular pathogenesis underlying these clinical phenotypes suggests that lethal trauma may involve excessive inflammation and coagulation disorders.

Characterisation of Ppy-lineage cells clarifies the functional heterogeneity of pancreatic beta cells in mice.

AIMS/HYPOTHESIS: Pancreatic polypeptide (PP) cells, which secrete PP (encoded by the Ppy gene), are a minor population of pancreatic endocrine cells. Although it has been reported that the loss of beta cell identity might be associated with beta-to-PP cell-fate conversion, at present, little is known regarding the characteristics of Ppy-lineage cells. METHODS: We used Ppy-Cre driver mice and a PP-specific monoclonal antibody to investigate the association between Ppy-lineage cells and beta cells. The molecular profiles of endocrine cells were investigated by single-cell transcriptome analysis and the glucose responsiveness of beta cells was assessed by Ca2+ imaging. Diabetic conditions were experimentally induced in mice by either streptozotocin or diphtheria toxin. RESULTS: Ppy-lineage cells were found to contribute to the four major types of endocrine cells, including beta cells. Ppy-lineage beta cells are a minor subpopulation, accounting for 12-15% of total beta cells, and are mostly (81.2%) localised at the islet periphery. Unbiased single-cell analysis with a Ppy-lineage tracer demonstrated that beta cells are composed of seven clusters, which are categorised into two groups (i.e. Ppy-lineage and non-Ppy-lineage beta cells). These subpopulations of beta cells demonstrated distinct characteristics regarding their functionality and gene expression profiles. Ppy-lineage beta cells had a reduced glucose-stimulated Ca2+ signalling response and were increased in number in experimental diabetes models. CONCLUSIONS/INTERPRETATION: Our results indicate that an unexpected degree of beta cell heterogeneity is defined by Ppy gene activation, providing valuable insight into the homeostatic regulation of pancreatic islets and future therapeutic strategies against diabetes. DATA AVAILABILITY: The single-cell RNA sequence (scRNA-seq) analysis datasets generated in this study have been deposited in the Gene Expression Omnibus (GEO) under the accession number GSE166164 ( www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE166164 ).

Analysis of clinical factors and reasons that influence the disposition of cryopreserved embryos in Japanese patients with infertility treated in our clinic.

AIM: To investigate the clinical factors and factors that affect the decisions regarding storage of cryopreserved embryos obtained using assisted reproductive technology. METHODS: Clinical characteristics affecting the decisions regarding cryopreserved embryos were analyzed in 5724 Japanese couples who underwent in vitro fertilization (IVF) or intra-cytoplasmic sperm insemination (ICSI) and embryo transfer over 4 years since April 2015 at our clinic. Statistical analysis was carried out using JMP software. RESULTS: The number of oocytes retrievals and embryos stored, outcomes and number of children, and age of the female patients and male partners were related to the decision-making regarding cryopreserved embryos. Childbearing and no wish for another child were the major reasons for discontinuing embryo storage. The number of oocytes retrievals and embryos in storage, age of the female patients, and sex of the child were independently associated with this decision-making in 2682 patients with a single child. Women with male children were more likely to choose discontinuation of embryo storage than those with female children. CONCLUSION: Already having a child and not wishing for further treatment due to age along with the presence of a male child affect the decision to continue or discontinue embryo storage in Japanese patients with infertility.

The Evaluation of Helicopter Emergency Medical Services With a Physician for Acute Myocardial Infarction in Japan: A Registry-Based Study of Prognosis and Time Reduction.

OBJECTIVE: The aim of this study was to compare the prognosis and time reduction between helicopter emergency medical services (HEMS) with a physician and ground emergency medical services (GEMS) in acute myocardial infarction (AMI) cases. METHODS: This is a registry-based study of the Japan Helicopter Emergency Medical Service Registry from April 1, 2015, to March 31, 2018. RESULTS: A total of 605 cases of AMI were registered in the HEMS group and 794 cases in the GEMS group. In the cases of non-cardiopulmonary arrest (CPA), the prognosis between HEMS and GEMS did not differ significantly. Regarding the road distance, for ranges of 20 to 40 km and > 40 km, the times from the call to the angiography room were significantly shorter with HEMS than GEMS (median 91 vs. 97 minutes, P = .036 and 101 vs. 132 minutes, P = .002, respectively). In cases of CPA, HEMS had a higher rate of return of spontaneous circulation than GEMS (55.3% vs. 36.8%, P = .038), but HEMS had a lower prognosis than GEMS (22.9% vs. 38.9%, P = .036). CONCLUSION: The present study suggested that HEMS had an advantage in reducing the time to angiography in AMI cases of non-CPA. In cases of CPA, HEMS increased the return of spontaneous circulation without improving the prognosis.

Does the endometrial thickness on the day of the trigger affect the pregnancy outcomes after fresh cleaved embryo transfer in the clomiphene citrate-based minimal stimulation cycle?

PURPOSE: Thin endometrium is often observed after clomiphene citrate (CC) administration for follicular development and is one of the reasons for embryo transfer (ET) cancelation or implantation failure. We retrospectively analyzed whether the endometrial thickness (EMT) on the days of the maturation trigger and ET are predictive factors of pregnancy outcomes after fresh cleaved ET in a CC-based minimal stimulation cycle (CC-cycle). METHODS: A total of 746 CC-cycles in vitro fertilization (IVF), followed by fresh cleaved ET, from November 2018 to March 2019 were analyzed. Associations between the pregnancy outcomes and EMT on the days of the trigger and ET were statistically evaluated. RESULTS: Although the EMT on the day of ET was not significantly associated with the ongoing pregnancy rate (adjusted odds ratio [AOR], 1.043; P = .3251), a decreased EMT on the day of the trigger was significantly associated with a low ongoing pregnancy rate (AOR, 1.154; P = .0042). Furthermore, the clinical pregnancy rate was significantly lower when the EMT was <7 mm on the day of the trigger during the CC-cycle. CONCLUSIONS: These results suggest that measurement of the EMT on the day of the trigger could be effective for predicting the pregnancy outcomes after fresh cleaved ET during the CC-cycle.

Development of monoclonal mouse antibodies that specifically recognize pancreatic polypeptide.

Pancreatic polypeptide (PP) is a 36-amino acid peptide encoded by the Ppy gene, which is produced by a small population of cells located in the periphery of the islets of Langerhans. Owing to the high amino acid sequence similarity among neuropeptide Y family members, antibodies against PP that are currently available are not convincingly specific to PP. Here we report the development of mouse monoclonal antibodies that specifically bind to PP. We generated Ppy knockout (Ppy-KO) mice in which the Ppy-coding region was replaced by Cre recombinase. The Ppy-KO mice were immunized with mouse PP peptide, and stable hybridoma cell lines producing anti-PP antibodies were isolated. Firstly, positive clones were selected in an enzyme-linked immunosorbent assay for reactivity with PP coupled to bovine serum albumin. During the screening, hybridoma clones producing antibodies that cross-react to the peptide YY (PYY) were excluded. In the second screening, hybridoma clones in which their culture media produce no signal in Ppy-KO islets but detect specific cells in the peripheral region of wild-type islets, were selected. Further studies demonstrated that the selected monoclonal antibody (23-2D3) specifically recognizes PP-producing cells, not only in mouse, but also in human and rat islets. The monoclonal antibodies with high binding specificity for PP developed in this study will be fundamental for future studies towards elucidating the expression profiles and the physiological roles of PP.

Web-Based Cognitive Behavioral Therapy Blended With Face-to-Face Sessions for Major Depression: Randomized Controlled Trial.

BACKGROUND: Meta-analyses of several randomized controlled trials have shown that cognitive behavioral therapy (CBT) has comparable efficacy to antidepressant medication, but therapist availability and cost-effectiveness is a problem. OBJECTIVE: This study aimed to evaluate the effectiveness of Web-based CBT blended with face-to-face sessions that reduce therapist time in patients with major depression who were unresponsive to antidepressant medications. METHODS: A 12-week, assessor-masked, parallel-group, waiting- list controlled, randomized trial was conducted at 3 medical institutions in Tokyo. Outpatients aged 20-65 years with a primary diagnosis of major depression who were taking ≥1 antidepressant medications at an adequate dose for ≥6 weeks and had a 17-item GRID-Hamilton Depression Rating Scale (HAMD) score of ≥14 were randomly assigned (1:1) to blended CBT or waiting-list groups using a computer allocation system, stratified by the study site with the minimization method, to balance age and baseline GRID-HAMD score. The CBT intervention was given in a combined format, comprising a Web-based program and 12 45-minute face-to-face sessions. Thus, across 12 weeks, a participant could receive up to 540 minutes of contact with a therapist, which is approximately two-thirds of the therapist contact time provided in the conventional CBT protocol, which typically provides 16 50-minute sessions. The primary outcome was the alleviation of depressive symptoms, as measured by a change in the total GRID-HAMD score from baseline (at randomization) to posttreatment (at 12 weeks). Moreover, in an exploratory analysis, we investigated whether the expected positive effects of the intervention were sustained during follow-up, 3 months after the posttreatment assessment. Analyses were performed on an intention-to-treat basis, and the primary outcome was analyzed using a mixed-effects model for repeated measures. RESULTS: We randomized 40 participants to either blended CBT (n=20) or waiting-list (n=20) groups. All patients completed the 12-week treatment protocol and were included in the intention-to-treat analyses. Participants in the blended CBT group had significantly alleviated depressive symptoms at week 12, as shown by greater least squares mean changes in the GRID-HAMD score, than those in the waiting list group (-8.9 points vs -3.0 points; mean between-group difference=-5.95; 95% CI -9.53 to -2.37; P<.001). The follow-up effects within the blended CBT group, as measured by the GRID-HAMD score, were sustained at the 3-month follow-up (week 24) and posttreatment (week 12): posttreatment, 9.4 (SD 5.2), versus follow-up, 7.2 (SD 5.7); P=.009. CONCLUSIONS: Although our findings warrant confirmation in larger and longer term studies with active controls, these suggest that a combined form of CBT is effective in reducing depressive symptoms in patients with major depression who are unresponsive to antidepressant medications. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry: UMIN000009242; https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000010852 (Archived by WebCite at http://www.webcitation. org/729VkpyYL).

Lack of a meaningful association between dietary patterns and in vitro fertilization outcome among Japanese women.

PURPOSE: The purpose of this study was to examine whether preconception maternal dietary pattern is associated with in vitro fertilization (IVF) outcome among Japanese women. METHODS: This prospective study included 140 Japanese women who underwent conventional-IVF/intracytoplasmic sperm injection. The patients' diets during the previous month before egg retrieval were assessed with validated brief-type self-administered diet history questionnaire. Dietary patterns from 33 predefined food groups [energy-adjusted food (g/1000 kcal)] were extracted by factor analysis. The primary outcome measure was clinical pregnancy rate after IVF. RESULTS: Thirty-six women had confirmed clinical pregnancy. Three dietary patterns were identified: "Vegetable and seafood," "Western," and "Rice and miso soup." The "Vegetables and seafood" dietary pattern (high intakes of green and other vegetables, mushrooms, seasoning, fish, soy products, chicken, and potatoes) was not associated with clinical pregnancy ([odds ratio per one-quartile increase in dietary pattern: 0.94 (95% confidence interval: 0.67-1.32), P = 0.73]. This relationship was unaltered after controlling for potential confounders. Furthermore, no association was seen between the other two dietary patterns and clinical pregnancy. CONCLUSIONS: The three maternal preconception dietary patterns identified revealed no meaningful association with IVF outcome in Japanese women. Further studies in various populations with different dietary patterns are needed to confirm these findings.

Positive Allosteric Modulation of the Calcium-sensing Receptor by Physiological Concentrations of Glucose.

The calcium-sensing receptor (CaSR) is activated by various cations, cationic compounds, and amino acids. In the present study we investigated the effect of glucose on CaSR in HEK293 cells stably expressing human CaSR (HEK-CaSR cells). When glucose concentration in the buffer was raised from 3 to 25 mm, a rapid elevation of cytoplasmic Ca2+ concentration ([Ca2+]c) was observed. This elevation was immediate and transient and was followed by a sustained decrease in [Ca2+]c The effect of glucose was detected at a concentration of 4 mm and reached its maximum at 5 mm 3-O-Methylglucose, a non-metabolizable analogue of glucose, reproduced the effect of glucose. Sucrose also induced an elevation of [Ca2+]c in HEK-CaSR cells. Similarly, sucralose was nearly as effective as glucose in inducing elevation of [Ca2+]c Glucose was not able to increase [Ca2+]c in the absence of extracellular Ca2+ The effect of glucose on [Ca2+]c was inhibited by NPS-2143, an allosteric inhibitor of CaSR. In addition, NPS-2143 also inhibited the [Ca2+]c responses to sucralose and sucrose. Glucose as well as sucralose decreased cytoplasmic cAMP concentration in HEK-CaSR cells. The reduction of cAMP induced by glucose was blocked by pertussis toxin. Likewise, sucralose reduced [cAMP]c Finally, glucose increased [Ca2+]c in PT-r parathyroid cells and in Madin-Darby canine kidney cells, both of which express endogenous CaSR. These results indicate that glucose acts as a positive allosteric modulator of CaSR.

Role of the glucose-sensing receptor in insulin secretion.

Glucose is a primary stimulator of insulin secretion. It has been thought that glucose exerts its effect by a mechanism solely dependent on glucose metabolism. We show here that glucose induces rapid Ca2+ and cyclic AMP signals in ß-cells. These rapid signals are independent of glucose-metabolism and are reproduced by non-metabolizable glucose analogues. These results led us to postulate that glucose activates a cell-surface receptor, namely the glucose-sensing receptor. Rapid signals induced by glucose are blocked by inhibition of a sweet taste receptor subunit T1R3 and a calcium-sensing receptor subunit CaSR. In accordance with these observations, T1R3 and CaSR form a heterodimer. In addition, a heterodimer of T1R3 and CaSR is activated by glucose. These results suggest that a heterodimer of T1R3 and CaSR is a major component of the glucose-sensing receptor. When the glucose-sensing receptor is blocked, glucose-induced insulin secretion is inhibited. Also, ATP production is significantly attenuated by the inhibition of the receptor. Conversely, stimulation of the glucose-sensing receptor by either artificial sweeteners or non-metabolizable glucose analogue increases ATP. Hence, the glucose-sensing receptor signals promote glucose metabolism. Collectively, glucose activates the cell-surface glucose-sensing receptor and promotes its own metabolism. Glucose then enters the cells and is metabolized through already activated metabolic pathways. The glucose-sensing receptor is a key molecule regulating the action of glucose in ß-cells.

Glycan profiling using formalin-fixed, paraffin-embedded tissues: Hippeastrum hybrid lectin is a sensitive biomarker for squamous cell carcinoma of the uterine cervix.

AIM: Glycosylation of proteins is altered in cancer cells and distinctive glycan structures are associated with specific cancers, but little is known about the complete glycan profile of particular tumors. In this study, glycomic analysis of squamous cell carcinoma (SCC) of the uterine cervix was performed to search for useful markers. METHODS: A lectin microarray containing 45 lectins with different binding preferences that covered N- and O-linked glycans was coupled with evanescent field-activated fluorescent detection for glycomic analysis of SCC and normal squamous epithelium (NSE) of the cervix. Formalin-fixed, paraffin-embedded tissue specimens were obtained from 16 patients with uterine cervical cancer. Sections that included both tumor and non-tumor tissues were examined to detect alterations of glycans based on the lectin-binding pattern. RESULTS: Hippeastrum hybrid lectin was found to be a sensitive marker for distinguishing SCC of the cervix from NSE. It was the best lectin for discriminating SCC from other tissues according to receiver-operator curve analysis, as it showed a high sensitivity (81.8%), a high specificity (70.1%), and a large area under the curve (0.8182). Histochemistry confirmed specific cytoplasmic staining of SCC cells by Hippeastrum hybrid lectin, while there was little staining of cervical intraepithelial neoplasia and no staining of NSE. CONCLUSION: The present lectin microarray technique could be applied for tissue-based glycomic analysis of various tumors and for discovery of glycan-related biomarkers.

Sucralose, an activator of the glucose-sensing receptor, increases ATP by calcium-dependent and -independent mechanisms.

Sucralose is an artificial sweetener and activates the glucose-sensing receptor expressed in pancreatic ß-cells. Although sucralose does not enter ß-cells nor acts as a substrate for glucokinase, it induces a marked elevation of intracellular ATP ([ATP]c). The present study was conducted to identify the signaling pathway responsible for the elevation of [ATP]c induced by sucralose. Previous studies have shown that sucralose elevates cyclic AMP (cAMP), activates phospholipase C (PLC) and stimulates Ca(2+) entry by a Na(+)-dependent mechanism in MIN6 cells. The addition of forskolin induced a marked elevation of cAMP, whereas it did not affect [ATP]c. Carbachol, an activator of PLC, did not increase [ATP]c. In addition, activation of protein kinase C by dioctanoylglycerol did not affect [ATP]c. In contrast, nifedipine, an inhibitor of the voltage-dependent Ca(2+) channel, significantly reduced [ATP]c response to sucralose. Removal of extracellular Na(+) nearly completely blocked sucralose-induced elevation of [ATP]c. Stimulation of Na(+) entry by adding a Na(+) ionophore monensin elevated [ATP]c. The monensin-induced elevation of [ATP]c was only partially inhibited by nifedipine and loading of BAPTA, both of which completely abolished elevation of [Ca(2+)]c. These results suggest that Na(+) entry is critical for the sucralose-induced elevation of [ATP]c. Both calcium-dependent and -independent mechanisms are involved in the action of sucralose.

Prolonged insulin stimulation down-regulates GLUT4 through oxidative stress-mediated retromer inhibition by a protein kinase CK2-dependent mechanism in 3T3-L1 adipocytes.

Although insulin acutely stimulates glucose uptake by promotion of GLUT4 translocation from intracellular compartments to the plasma membrane in adipocytes and muscles, long term insulin stimulation causes GLUT4 depletion that is particularly prominent in the insulin-responsive GLUT4 storage compartment. This effect is caused mainly by accelerated lysosomal degradation of GLUT4, although the mechanism is not fully defined. Here we show that insulin acutely induced dissociation of retromer components from the low density microsomal membranes of 3T3-L1 adipocytes that was accompanied by disruption of the interaction of Vps35 with sortilin. This insulin effect was dependent on the activity of protein kinase CK2 but not phosphatidylinositol 3-kinase or extracellular signal-regulated kinase 1/2. Knockdown of Vps26 decreased GLUT4 to a level comparable with that with insulin stimulation for 4 h. Vps35 with a mutation in the CK2 phosphorylation motif (Vps35-S7A) was resistant to insulin-induced dissociation from the low density microsomal membrane, and its overexpression attenuated GLUT4 down-regulation with insulin. Furthermore, insulin-generated hydrogen peroxide was an upstream mediator of the insulin action on retromer and GLUT4. These results suggested that insulin-generated oxidative stress switches the GLUT4 sorting direction to lysosomes through inhibition of the retromer function in a CK2-dependent manner.

Effective internalization of U251-MG-secreted exosomes into cancer cells and characterization of their lipid components.

Exosomes, the natural vehicles of various biological molecules, have been examined in several research fields including drug delivery. Although understanding of the biological functions of exosomes has increased, how exosomes are transported between cells remains unclear. We hypothesized that cell tropism is important for effective exosomal intercellular communication and that parental cells regulate exosome movement by modulating constituent exosomal molecules. Herein, we demonstrated the strong translocation of glioblastoma-derived exosomes (U251exo) into their parental (U251) cells, breast cancer (MDA-MB-231) cells, and fibrosarcoma (HT-1080). Furthermore, disruption of proteins of U251exo by enzymatic treatment did not affect their uptake. Therefore, we focused on lipid molecules of U251exo with the expectation that they are crucial for effective incorporation of U251exo by cancer cells. Phosphatidylethanolamine was identified as a unique lipid component of U251-MG cell-derived extracellular vesicles. From these results, valuable insight is provided into the targeting of U251exo to cancer cells, which will help to develop a cancer-targeted drug delivery system.

Glucose-Sensing Receptor T1R3: A New Signaling Receptor Activated by Glucose in Pancreatic ß-Cells.

Subunits of the sweet taste receptors T1R2 and T1R3 are expressed in pancreatic ß-cells. Compared with T1R3, mRNA expression of T1R2 is considerably lower. At the protein level, expression of T1R2 is undetectable in ß-cells. Accordingly, a major component of the sweet taste-sensing receptor in ß-cells may be a homodimer of T1R3 rather than a heterodimer of T1R2/T1R3. Inhibition of this receptor by gurmarin or deletion of the T1R3 gene attenuates glucose-induced insulin secretion from ß-cells. Hence the T1R3 homodimer functions as a glucose-sensing receptor (GSR) in pancreatic ß-cells. When GSR is activated by the T1R3 agonist sucralose, elevation of intracellular ATP concentration ([ATP]i) is observed. Sucralose increases [ATP]i even in the absence of ambient glucose, indicating that sucralose increases [ATP]i not simply by activating glucokinase, a rate-limiting enzyme in the glycolytic pathway. In addition, sucralose augments elevation of [ATP]i induced by methylsuccinate, suggesting that sucralose activates mitochondrial metabolism. Nonmetabolizable 3-O-methylglucose also increases [ATP]i and knockdown of T1R3 attenuates elevation of [ATP]i induced by high concentration of glucose. Collectively, these results indicate that the T1R3 homodimer functions as a GSR; this receptor is involved in glucose-induced insulin secretion by activating glucose metabolism probably in mitochondria.

Glucose promotes its own metabolism by acting on the cell-surface glucose-sensing receptor T1R3.

A homodimer of taste type 1 receptor 3 (T1R3) functions as a sweet taste-sensing receptor in pancreatic ß-cells. This receptor is activated by various sweet molecules including sugars such as glucose. To determine the role of this receptor in glucose-induced insulin secretion, we addressed whether or not this receptor modulates glucose metabolism in MIN6 cells. We measured changes in intracellular ATP ([ATP]i) in MIN6 cells expressing luciferase. Sucralose, an agonist of T1R3, induced immediate and sustained elevation of [ATP]i in the presence of 5.5 mM glucose. The effect of sucralose was dose-dependent and, at 5 mM, was greater than that induced by 25 mM glucose. In contrast, carbachol, GLP-1 or high concentration of potassium did not reproduce the sucralose action. Sucralose facilitated the increase in [ATP]i induced by a mitochondrial fuel methylsuccinate, and potentiated glucose-induced elevation of [ATP]i. Administration of a non-metabolizable glucose analogue, 3-O-methylglucose, which acts as an agonist of T1R3, induced a small and transient increase in [ATP]i. 3-O-Methylglucose augmented elevation of [ATP]i induced by methylsuccinate, and also enhanced glucose-induced increase in [ATP]i. Knock down of T1R3 by using shRNA attenuated [ATP]i-response to high concentration of glucose and also reduced the glucose-induced insulin secretion. These results indicate that activation of the homodimer of T1R3 facilitates the metabolic pathway in mitochondria and augments ATP production. The results obtained by using 3-O-methylglucose suggest that glucose, by acting on the homodimer of T1R3, promotes its own metabolism.

Expression of the glucose-sensing receptor T1R3 in pancreatic islet: changes in the expression levels in various nutritional and metabolic states.

We reported recently that the taste type 1 receptor 3 (T1R3), a subunit of the sweet taste receptor, functions as a cell-surface glucose-sensing receptor in pancreatic ß-cells. In the present study, we investigated the expression of T1R3 in pancreatic islets. mRNA for T1R2 and T1R3 was detected in mouse pancreatic islets. Quantitatively, the mRNA expression level of T1R2 was less than 1% of that of T1R3. Immunohistochemically, T1R3 was abundantly expressed in mouse islets whereas T1R2 was barely detected. Most immunoreactive T1R3 was colocalized with insulin and almost all ß-cells were positive for T1R3. In addition, T1R3 was expressed in some portion of α-cells. Immunoreactivity of T1R3 in ß-cells was markedly reduced in fed mice compared to those in fasting mice. In contrast, mRNA for T1R3 was not different in islets of fasting and fed mice. Glucose-induced insulin-secretion was higher in islets obtained from fasting mice compared to those from fed mice. The expression of T1R3 was markedly reduced in islets of ob/ob mice compared to those of control mice. Similarly, the expression of T1R3 was reduced in islet of db/db mice. In addition, the expression of T1R3 was markedly reduced in ß-cells of fatty diabetic rats and GK rats, models of obese and non-obese type 2 diabetes, respectively. These results indicate that T1R3 is expressed mainly in ß-cells and the expression levels are different depending upon the nutritional and metabolic conditions.

Association between lung contusion volume and acute changes in fibrinogen levels: A single-center observational study.

Aim: Organ tissue damage, including the lungs, may lead to acute coagulopathy. This study aimed to evaluate the association between lung contusion volume and serum fibrinogen level during the acute phase of trauma. Methods: We conducted an observational study using electronic medical records at a tertiary-care center between January 2015 and December 2018. We included patients with lung contusions on hospital arrival. We used three-dimensional computed tomography to calculate lung contusion volumes. The primary outcome was the lowest fibrinogen level measured within 24 h of hospital arrival. We evaluated the association between lung contusion volume and outcome with multivariable linear regression analysis. Also, we calculated the sensitivity and specificity of lung contusion volume in patients with a serum fibrinogen level of ≤150 mg/dL. Results: We identified 124 eligible patients. Their median age was 43.5 years, and 101 were male (81.5%). The median lung contusion volume was 10.9%. The median lowest fibrinogen level within 24 h from arrival was 188.0 mg/dL. After adjustment, lung contusion volume had a statistically significant association with the lowest fibrinogen level within 24 h from arrival (coefficient -1.6, 95% confidence interval -3.16 to -0.07). When a lung contusion volume of 20% was used as the cutoff, the sensitivity and specificity to identify fibrinogen depletion were 0.27 and 0.95, respectively. Conclusion: Lung contusion volume was associated with the lowest fibrinogen level measured within 24 h from hospital arrival. Measuring lung contusion volume may help to identify patients with a progression of fibrinogen depletion.

Multimodal function of the sweet taste receptor expressed in pancreatic ß-cells: generation of diverse patterns of intracellular signals by sweet agonists.

The sweet taste receptor is expressed in the taste bud and is activated by numerous sweet molecules with diverse chemical structures. It is, however, not known whether these sweet agonists induce a similar cellular response in target cells. Using MIN6 cells, a pancreatic ß-cell line expressing endogenous sweet taste receptor, we addressed this question by monitoring changes in cytoplasmic Ca2+ ([Ca2+]i) and cAMP ([cAMP]i) induced by four sweet taste receptor agonists. Glycyrrhizin evoked sustained elevation of [Ca2+]i but [cAMP]i was not affected. Conversely, an artificial sweetener saccharin induced sustained elevation of [cAMP]i but did not increase [Ca2+]i. In contrast, sucralose and acesulfame K induced rapid and sustained increases in both [Ca2+]i and [cAMP]i. Although the latter two sweeteners increased [Ca2+]i and [cAMP]i, their actions were not identical: [Ca2+]i response to sucralose but not acesulfame K was inhibited by gurmarin, an antagonist of the sweet taste receptor which blocks the gustducin-dependent pathway. In addition, [Ca2+]i response to acesulfame K but not to sucralose was resistant to a Gq inhibitor. These results indicate that four types of sweeteners activate the sweet taste receptor differently and generate distinct patterns of intracellular signals. The sweet taste receptor has amazing multimodal functions producing multiple patterns of intracellular signals.