Detection of Pulmonary Embolism Using a Novel Dynamic Flat-Panel Detector System in Monkeys.

BACKGROUND: Recently, dynamic chest radiography (DCR) was developed to evaluate pulmonary function using a flat-panel detector (FPD), which can evaluate blood flow in the pulmonary artery without injection of contrast agents. This study investigated the ability of a FPD to measure physiological changes in blood flow and to detect pulmonary embolism (PE) in monkeys.Methods and Results:DCR was performed in 5 monkeys using a FPD. Regions of interest (ROI) were placed in both lung fields of the image, and maximum changes in pixel value (∆pixel value) in the ROI were measured during 1 electrocardiogram cardiac cycle. Next, a PE model was induced using a Swan-Ganz catheter and additional images were taken. The ∆pixel value of the lungs in normal and PE models were compared in both supine and standing positions. The lung ∆pixel value followed the same cycle as the monkey electrocardiogram. ∆pixel values in the upper lung field decreased in the standing as compared to the supine position. In the PE model, the ∆pixel value decreased in the area of pulmonary blood flow occlusion and increased in the contralateral lung as compared to the normal model (normal model 1.287±0.385, PE model occluded side 0.428±0.128, PE model non-occluded side 1.900±0.431). CONCLUSIONS: A FPD could detect postural changes in pulmonary blood flow and its reduction caused by pulmonary artery occlusion in a monkey model.

Gestational psittacosis: A case report and literature review.

Gestational psittacosis is a rare disease that is associated with significant maternal and fetal morbidity and mortality. Currently, there is no examination method which allows for a quick diagnosis. We report a case of gestational psittacosis that could not be diagnosed as psittacosis during treatment and resulted in maternal and fetal death despite intensive treatment. We also reviewed 23 cases of gestational psittacosis. Fetal and maternal mortality was 82.6% (19/23) and 8.7% (2/23), respectively. In pregnant women with high fever and flu-like symptoms, we should suspect Chlamydia psittaci infection if at least one of the following is present; contact with sheep, parrots, parakeets or goats; normal or moderately decreased leucocyte count, thrombocytopenia and hepatic and/or renal dysfunction; cough and/or lobe consolidation or infiltration on chest X-ray. Antibiotic therapy with macrolide prenatally, macrolide or tetracycline postnatally and termination of pregnancy should be considered.

The approval of revised diagnostic criteria for DIC from the Japanese Society on Thrombosis and Hemostasis.

As proposed diagnostic criteria for DIC from the Japanese Society on Thrombosis and Hemostasis has been approved and revised, the contents and changes are informed.

Proposal for new diagnostic criteria for DIC from the Japanese Society on Thrombosis and Hemostasis.

Disseminated intravascular coagulation (DIC) is a serious disease that, in the presence of underlying disease, causes persistent, generalized, marked coagulation activation. Early treatment based on an appropriate diagnosis is very important for improving patients' prognosis, to which end diagnostic criteria play a key role. Several criteria have been proposed, but each has its strengths and weaknesses, and improved criteria are needed. Widespread use of coagulofibrinolytic markers has elucidated that the pathology of DIC differs greatly as a function of the underlying disease. Thus, discriminating use of DIC diagnostic criteria that take underlying diseases into account is important. DIC diagnostic criteria that are well known in Japan include the Japanese Ministry of Health and Welfare's old DIC diagnostic criteria (JMHW criteria), the International Society on Thrombosis and Haemostasis's DIC diagnostic criteria (ISTH criteria), and the Japanese Association for Acute Medicine's acute-stage DIC diagnostic criteria (JAAM criteria). Those criteria have their respective drawbacks: the sensitivity of the ISTH criteria is poor, the JAAM criteria cannot be applied to all underlying diseases, and the JMHW criteria have poor sensitivity in the case of infections, do not use molecular markers, and result in misdiagnosis. The Japanese Society on Thrombosis and Hemostasis's newly proposed provisional draft DIC diagnostic criteria (new criteria) use diagnostic criteria classifications of "hematopoietic disorder type", "infectious type", and "basic type" based on the underlying pathology. For the hematopoietic disorder type the platelet count is omitted from the score, while for the infectious type, fibrinogen is omitted from the score. Also, points are added if the platelet count decreases with time. In the new criteria, molecular markers and antithrombin activity have been newly included, and as a countermeasure for misdiagnosis, 3 points are deducted if there is liver failure. In this paper, we discuss various problems encountered with DIC diagnosis, and we describe the new criteria together with the events that led to their creation. These new diagnostic criteria take into account the underlying diseases of wide area, and we expect that they will serve clinicians well due to the above adaptations and improvements.

Recombinant soluble human thrombomodulin (thrombomodulin alfa) in the treatment of neonatal disseminated intravascular coagulation.

UNLABELLED: Recombinant soluble human thrombomodulin (TM-α) has been shown to be useful in the treatment of disseminated intravascular coagulation (DIC) in a heparin-controlled study and has been available for clinical use in Japan since 2008. However, data on its use for neonatal DIC have not been reported from any clinical studies, so efficacy and safety were analyzed in 60 neonatal DIC patients identified in post-marketing surveillance. The DIC resolution rate as of the day after last administration of TM-α was 47.1 %, and the survival rate at 28 days after last administration was 76.7 %. Hemostatic test result profiles revealed decreased levels of fibrin/fibrinogen degradation products and increased platelet counts and antithrombin activity. Incidences of adverse drug reactions, bleeding-related adverse drug reactions, and bleeding-related adverse events were 6.7, 6.7, and 16.7 %, respectively, with no significant differences between neonatal, pediatric (excluding neonates), and adult DIC patients. CONCLUSION: This surveillance provided real-world data on the safety and effectiveness of TM-alpha in the treatment of neonatal DIC in general practice settings.

A randomized, controlled, multicenter trial of the effects of antithrombin on disseminated intravascular coagulation in patients with sepsis.

INTRODUCTION: To test the hypothesis that the administration of antithrombin concentrate improves disseminated intravascular coagulation (DIC), resulting in recovery from DIC and better outcomes in patients with sepsis, we conducted a prospective, randomized controlled multicenter trial at 13 critical care centers in tertiary care hospitals. METHODS: We enrolled 60 DIC patients with sepsis and antithrombin levels of 50 to 80% in this study. The participating patients were randomly assigned to an antithrombin arm receiving antithrombin at a dose of 30 IU/kg per day for three days or a control arm treated with no intervention. The primary efficacy end point was recovery from DIC on day 3. The analysis was conducted with an intention-to-treat approach. DIC was diagnosed according to the Japanese Association for Acute Medicine (JAAM) scoring system. The systemic inflammatory response syndrome (SIRS) score, platelet count and global markers of coagulation and fibrinolysis were measured on day 0 and day 3. RESULTS: Antithrombin treatment resulted in significantly decreased DIC scores and better recovery rates from DIC compared with those observed in the control group on day 3. The incidence of minor bleeding complications did not increase, and no major bleeding related to antithrombin treatment was observed. The platelet count significantly increased; however, antithrombin did not influence the sequential organ failure assessment (SOFA) score or markers of coagulation and fibrinolysis on day 3. CONCLUSIONS: Moderate doses of antithrombin improve DIC scores, thereby increasing the recovery rate from DIC without any risk of bleeding in DIC patients with sepsis. TRIAL REGISTRATION: UMIN Clinical Trials Registry (UMIN-CTR) UMIN000000882.

The ability of endotoxin adsorption during a longer duration of direct hemoperfusion with a polymyxin B-immobilized fiber column in patients with septic shock.

The patients' hemodynamic conditions of septic shock due to intra-abdominal infection were improved by the longer duration of direct hemoperfusion with a polymyxin B-immobilized fiber column (PMX), reducing plasma endotoxins measured by the novel endotoxin detection method, named endotoxin scattering photometry (ESP) method; however, turbidimetric method could not detect endotoxins. We also observed the reduction in the endotoxin after passing through column by ESP method even after the longer duration of PMX. ESP method may more sensitively detect endotoxins than the ordinary turbidimetric method. Moreover, we demonstrated the ability of endotoxin adsorption in spite of the longer duration of PMX.

Treatments for Trauma-Induced Coagulopathy: Protocol for a Systematic Review and Meta-Analysis.

BACKGROUND: Trauma-induced coagulopathy (TIC) is a common and potentially life-threatening coagulopathy as a result of traumatic injury, characterized by abnormal blood clotting and bleeding. Although several treatments have been proposed for TIC, their effectiveness and safety remain unclear. Further, numerous systematic reviews and meta-analyses on trauma have been conducted; however, to our knowledge, there is no systematic review and meta-analysis that specifically focuses on TIC management. Therefore, a comprehensive synthesis of the available evidence on interventions for TIC is needed. OBJECTIVE: This systematic review and meta-analysis aim to evaluate the effectiveness and safety of interventions for the management of TIC. METHODS: We will conduct a systematic review and meta-analysis of randomized and nonrandomized controlled trials as well as observational studies regarding severe trauma in patients with TIC. The interventions will include administration of coagulation factor concentrates, tranexamic acid, and blood component products. The control group will be managed with an ordinal transfusion or administered placebo. The primary outcome will be in-hospital mortality. We will search the electronic databases of MEDLINE (PubMed), Web of Science, and the Cochrane Central Register of Controlled Trials. Two reviewers will independently screen the titles and abstracts, retrieve the full text of the selected articles, and extract essential data. We will apply uniform criteria for evaluating the risk of bias associated with individual randomized controlled trials and nonrandomized trials based on the Cochrane risk-of-bias tool. Risk ratio values will be expressed as point estimates with 95% CIs. Continuous variables will be expressed as the mean difference along with their 95% CIs and P values. We will assess the strength of evidence using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. This review will be the first systematic review and meta-analysis providing information on the effectiveness and safety of interventions for the management of TIC, including the administration of coagulation factor concentrates, tranexamic acid, and blood component products. Ethics approval and patient consent were not required for this study protocol, as we conducted a systematic review and meta-analysis of publicly available data, without any direct involvement of human participants. RESULTS: We will summarize the selection of the eligible studies using a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart. The results will be presented in a table summarizing the evidence. The results of the meta-analysis will be depicted using figures and forest plots. CONCLUSIONS: This systematic review will provide updated information on the efficacy and safety of using coagulation factor concentrates, tranexamic acid, and blood component products for patients with TIC. To our knowledge, there is no systematic review and meta-analysis that specifically focuses on treatments for TIC. TRIAL REGISTRATION: UMIN registry UMIN000050170; https://tinyurl.com/yr8pcrj6. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/49582.

Decreasing Plasma Fibrinogen Levels in the Intensive Care Unit Are Associated with High Mortality Rates In Patients With Sepsis-Induced Coagulopathy.

Plasma fibrinogen levels increase in response to infection, but they could also decrease due to degradation as in severe coagulopathy. We evaluated 60 septic patients with their CRP levels over 5.00 mg/dL. The patients were classified into three groups based on the ratio of the maximum or minimum fibrinogen concentration within day 3 to the initial concentration on day 0: down-, flat, and uptrend groups (n = 15, 30, and 15, respectively). Both down- and flat trend groups showed reduced inflammatory markers on day 3, and the degree of platelet loss (103/µL) and the mortality rate (%) were more remarkable in the downtrend group ( - 108 vs - 42 [p = 0.026] and 46.7 vs 10.0 [p = 0.027]). On day 0, in total 12 and 9 patients were diagnosed with non-overt DIC in the down- and uptrend groups, of which 5 (41.7%) and 1 (11.1%) died within 28 days after admission. In conclusion, decreasing fibrinogen levels in the ICU are associated with high mortality in patients with sepsis followed by decreasing platelet counts, even when they are diagnosed with non-overt DIC.

Benefit Profile of Thrombomodulin Alfa Combined with Antithrombin Concentrate in Patients with Sepsis-Induced Disseminated Intravascular Coagulation.

Thrombomodulin alfa (TM-α, recombinant human soluble thrombomodulin) and antithrombin (AT) concentrate are anticoagulant agents for the treatment of disseminated intravascular coagulation (DIC). A post hoc analysis using data from 1198 patients with infection-induced DIC from the post-marketing surveillance of TM-α was conducted. To identify subgroups that benefit from combination therapy, the patients were a priori stratified into four groups by a platelet (Plt) count of 50 × 103/µL and plasma AT level of 50% (groups 1, 2, 3, and 4, with high Plt/high AT, high Plt/low AT, low Plt/high AT, and low Plt/low AT, respectively). Kaplan-Meier survival analysis showed significantly worse survival in groups 2 and 4 had than in group 1 (p = 0.0480, p < 0.0001, respectively), and multivariate analysis showed that concomitant AT concentrate was independently correlated with reduced 28-day mortality only in group 4 (hazard ratio 0.6193; 95% confidence interval, 0.3912-0.9805). The adverse drug reactions (ADRs) and bleeding ADRs were not different among the groups. Patients with both severe thrombocytopenia and AT deficiency are candidates for combined anticoagulant therapy with TM-α and AT concentrate.

Mortality at 180-days is affected by serum haptoglobin levels in septic patients with high magnitude serum high mobility group box-1 levels.

AIM: High mobility group box-1 (HMGB1) is a lethal mediator of sepsis that binds to haptoglobin (Hp) and is associated with its prognosis. We investigated the effect of the combination of HMGB1 and Hp on sepsis prognosis. METHODS: This single-center, retrospective study registered 78 patients with sepsis according to Sepsis-3 criteria on day 1 of diagnosis from July 2016 to November 2018. We divided the patients into four groups according to the serum concentration of 6.2 ng/mL HMGB1 and the median value of Hp. The 180-day mortality rates and cytokine concentrations of the low and high HMGB1 groups were compared. RESULTS: There was no difference in the 180-day mortality rate between the low Hp group and the high Hp group in the low HMGB1 group (P = 0.691). In the high HMGB1 group, a statistically significant difference was found between the low Hp group and the high Hp group (P = 0.002). In the high HMGB1 group, high Hp was associated with a better prognosis in univariate analysis (odds ratio, 0.131; 95% confidence interval [CI], 0.027-0.629; P = 0.011), and multivariate analysis (adjusted odds ratio, 0.086; 95% CI, 0.013-0.582; P = 0.009). In addition, in the high HMGB1 group, interleukin-8 levels were significantly higher in the low Hp group than in the high Hp group (P = 0.004). CONCLUSION: Patients with sepsis-induced high serum HMGB1 levels and low serum Hp levels could have a poor long-term prognosis.

Lipocalin-type prostaglandin D synthase is associated with coronary vasospasm and vasomotor reactivity in response to acetylcholine.

BACKGROUND: Lipocalin-type prostaglandin D synthase (L-PGDS) catalyzes the biosynthesis of PGD(2), which acts as an anticoagulant, vasodilator, and inflammatory mediator. We examined the serum L-PGDS level, coronary macro- and microvasomotor functions, and their relationship in patients with chest pain and angiographically normal coronary arteries. METHODS AND RESULTS: The study included 96 patients who underwent diagnostic coronary angiography and had angiographically normal coronary arteries. Blood flow of the left anterior descending coronary artery (LAD) was analyzed by Doppler guidewire examination. Serum L-PGDS level was determined by ELISA. Infusion of acetylcholine (ACh) induced vasospasm of the LAD in all patients with vasospastic angina (VSA) (n=45), but in none of the patients without VSA (n=51). There were no significant differences in the baseline clinical characteristics of the nonVSA and VSA groups, except for the frequency of smoking. Serum L-PGDS level in the VSA group was significantly higher than that in the nonVSA group (77.1±4.4 vs. 63.9±2.5 µg/dl, P<0.01). Significant negative correlations were observed between the degree of LAD vasomotion in response to ACh and serum L-PGDS level (3 µg/min: r=-0.33; 10 µg/min: r=-0.35; 30 µg/min: r=-0.33, P<0.01). CONCLUSIONS: The L-PGDS level was elevated in patients with VSA and was associated with epicardial coronary vasomotion in response to ACh.

Homing of the bone marrow-derived interstitial cells of Cajal is decreased in diabetic mouse intestine.

BACKGROUND: Interstitial cells of Cajal (ICCs), which express c-Kit receptor tyrosine kinase (KIT), play an important role in gastrointestinal motility. Loss of ICCs likely contributes to diabetic gastrointestinal motility disorder, however, the mechanism of attrition remains unknown. Here, we test the hypothesis that the bone marrow-derived progenitors are an important source of intestinal ICCs and that decreased homing of these progenitors in diabetes contributes to ICC diminution. METHODS: Wild type mice were X-ray irradiated, transplanted with bone marrow (BMT) from green fluorescence protein (GFP)-transgenic (TG)-mice and subsequently made diabetic by streptozotocin (STZ) injection. Intestinal homing of GFP-positive bone marrow-derived cells was examined 2 or 5 months after STZ treatment. RESULTS: In the BMT-mice, we found many GFP-positive bone marrow-derived cells (BMDCs) in most parts of the intestinal area, the number of BMDCs was significantly decreased in diabetic mice compared with nondiabetic controls. As a representative area, we further examined the myenteric plexus of the proximal small intestine, and found that the cell numbers of ICCs marked by c-Kit-positive immunoreactivity were decreased by more than 40% in diabetic versus nondiabetic mice. Furthermore, numbers of c-Kit+/GFP+ and c-Kit+/GFP- cells were similar in nondiabetic mice, and decreased by 45.8% and 42.0%, respectively, in diabetic mice. CONCLUSION: These results suggest that the decreased homing from the bone marrow is a major cause of ICC loss in the intestine in diabetes mellitus.

Association between plasma complement factor H concentration and clinical outcomes in patients with sepsis.

AIM: The complement system is important for defending against pathogens, however, excessive complement activation is associated with a poor prognosis and organ dysfunction in sepsis. Complement factor H (CFH) acts to prevent excessive complement activation and damage to the self through the regulation of the complement alternative pathway. We investigated the association between plasma CFH levels on admission to the intensive care unit (ICU) and 90-day mortality, severity scores, and organ dysfunction in patients with sepsis. METHODS: We assessed the relationship between the plasma CFH on admission to the ICU and 90-day mortality, severity scores such as the Acute Physiology and Chronic Health Evaluation II score, Sequential Organ Failure Assessment score, and Simplified Acute Physiology Score 2, and organ dysfunction. RESULTS: This analysis included 62 patients. The plasma CFH levels were significantly lower in 90-day non-survivors than in survivors (70.0 µg/mL [interquartile range, 51.2-97.6] versus 104.8 µg/mL [interquartile range, 66.8-124.2]; P = 0.006) . The plasma CFH levels were associated with 90-day mortality (odds ratio 0.977; 95% confidence interval, 0.957-0.994; P = 0.01). The plasma CFH levels were negatively correlated with severity scores. The Sequential Organ Failure Assessment scores for the coagulation and neurological components were negatively correlated with the CFH concentration. CONCLUSION: Lower plasma levels of CFH were associated with increased severity and mortality in patients with sepsis on admission to the ICU and were correlated with central nervous system dysfunction and coagulopathy.

Impact of abdominal aortic calcification on 90-day mortality in sepsis patients: a pilot retrospective cohort study.

AIM: We aimed to investigate the association between aortic calcification and 90-day mortality in sepsis patients admitted to the intensive care unit. METHODS: We evaluated adult patients (≥18 years) diagnosed with sepsis based on the Sepsis-3 criteria and admitted to our intensive care unit between April 2011 and March 2015. They were classified according to the degree of abdominal aortic calcification (severe and non-severe), grouped per age (<65, 65-75, and >75 years), and matched. Survival curves were generated, and between-group differences were evaluated. RESULTS: Overall, 164 patients were included. The Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores were not significantly different between the severity groups, whereas there were significant differences in age (P < 0.001), sex (P = 0.017), and presence of diabetes mellitus (P < 0.001), hypertension (P < 0.001), dyslipidemia (P = 0.048), and maintenance dialysis (P = 0.001). The severe abdominal aortic calcification group showed significantly poorer prognosis than the non-severe group (log-rank P = 0.009). The adjusted odds ratio of severe calcification was the highest in patients aged <65 years (7.167; 95% confidence interval, 1.042-49.28, P = 0.045). Twenty-eight patients from each group were matched. The 90-day survival rate of the severe calcification group remained significantly lower than that of the non-severe calcification group (53.6% [15/28] versus 82.1% [23/28], P = 0.022). CONCLUSIONS: Severe abdominal aortic calcification is associated with the 90-day mortality of sepsis patients, particularly among those aged <65 years. Thus, caution is necessary in patients younger than 65 years; they may need to be treated with as much care as the elderly.

Malfunctioning CD106-positive, short-term hematopoietic stem cells trigger diabetic neuropathy in mice by cell fusion.

Diabetic neuropathy is an incurable disease. We previously identified a mechanism by which aberrant bone marrow-derived cells (BMDCs) pathologically expressing proinsulin/TNF-α fuse with residential neurons to impair neuronal function. Here, we show that CD106-positive cells represent a significant fraction of short-term hematopoietic stem cells (ST-HSCs) that contribute to the development of diabetic neuropathy in mice. The important role for these cells is supported by the fact that transplantation of either whole HSCs or CD106-positive ST-HSCs from diabetic mice to non-diabetic mice produces diabetic neuronal dysfunction in the recipient mice via cell fusion. Furthermore, we show that transient episodic hyperglycemia produced by glucose injections leads to abnormal fusion of pathological ST-HSCs with residential neurons, reproducing neuropathy in nondiabetic mice. In conclusion, we have identified hyperglycemia-induced aberrant CD106-positive ST-HSCs underlie the development of diabetic neuropathy. Aberrant CD106-positive ST-HSCs constitute a novel therapeutic target for the treatment of diabetic neuropathy.

The Japanese Society for Apheresis clinical practice guideline for therapeutic apheresis.

Most of the diseases for which apheresis therapy is indicated are intractable and rare, and each patient has a different background and treatment course prior to apheresis therapy initiation. Therefore, it is difficult to conduct large-scale randomized controlled trials to secure high-quality evidence. Under such circumstances, the American Society for Apheresis (ASFA) issued its guidelines in 2007, which were repeatedly revised until the latest edition in 2019. The ASFA guidelines are comprehensive. However, in the United States, a centrifugal separation method is mainly used for apheresis, whereas the mainstream procedure in Japan is the membrane separation method. The target diseases and their backgrounds are different from those in Japan. Due to these differences, the direct adoption of the ASFA guidelines in Japanese practice creates various problems. One of the features of apheresis in Japan is the development of treatment methods using hollow-fiber devices such as double filtration plasmapheresis (DFPP) and selective plasma exchange and adsorption-type devices such as polymyxin B-immobilized endotoxin adsorption columns. Specialists in emergency medicine, hematology, collagen diseases/rheumatology, respiratory medicine, cardiovascular medicine, gastroenterology, neurology, nephrology, and dermatology who are familiar with apheresis therapy gathered for this guideline, which covers 86 diseases. In addition, since apheresis therapy involves not only physicians but also clinical engineers, nurses, dieticians, and many other medical professionals, this guideline was prepared in the form of a worksheet so that it can be easily understood at the bedside. Moreover, to the clinical purposes, this guideline is designed to summarize apheresis therapy in Japan and to disseminate and further develop Japanese apheresis technology to the world. As diagnostic and therapeutic techniques are constantly advancing, the guidelines need to be revised every few years. In order to ensure the high quality of apheresis therapy in Japan, both the Japanese Society for Apheresis Registry and the guidelines will be inseparable.

Aquaporin 7 is a beta-cell protein and regulator of intraislet glycerol content and glycerol kinase activity, beta-cell mass, and insulin production and secretion.

To investigate if intracellular glycerol content plays a role in the regulation of insulin secretion in pancreatic beta cells, we studied the expression of the glycerol channels, or aquaglyceroporins, encoded by the aquaporin 3 (Aqp3), Aqp7, and Aqp9 genes in mouse islets. We found expression of Aqp7 only, not that of Aqp3 or Aqp9, in the endocrine pancreas at both the mRNA (by reverse transcription-PCR) and protein (by immunohistochemistry) levels. Immunohistochemistry revealed a complete overlap between insulin and Aqp7 immunostaining in the pancreatic islet. Inactivation of Aqp7 by gene targeting produced viable and healthy mice. Aqp7-/- mice harbored an increased intraislet glycerol concentration with a concomitant increase of the glycerol kinase transcript level and enzyme activity. The islet triglyceride content in the Aqp7-/- mice was also increased compared to that in the Aqp7+/+ mice. Interestingly, Aqp7-/- mice displayed reduced beta-cell mass and insulin content but increased insulin-1 and insulin-2 mRNAs. The reduction of beta-cell mass in Aqp7-/- mice can be explained at least in part by a reduction in cell proliferation through protein kinase C and the c-myc cascade, with a reduction in the transcript levels of these two genes. Concomitantly, there was a decreased rate of apoptosis, as reflected by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling and caspase 3 and Bax expression in Aqp7-/- mice. Compared with Aqp7+/+ islets, islets isolated from Aqp7-/- mice secreted insulin at a higher rate under basal low-glucose conditions and on exposure to a high (450 mg/dl) glucose concentration. Aqp7-/- mice exhibited normal fasting blood glucose levels but elevated blood insulin levels. Their plasma glucose response to an intraperitoneal (i.p.) glucose tolerance test was normal, but their plasma insulin concentrations were higher than those of wild-type mice during the 2-h test. An i.p. insulin tolerance test showed similar plasma glucose lowering in Aqp7-/- and Aqp7+/+ mice, with no evidence of insulin resistance. In conclusion, we found that pancreatic beta cells express AQP7, which appears to be a key regulator of intraislet glycerol content as well as insulin production and secretion.