The dual GCGR/GLP-1R agonist survodutide: Biomarkers and pharmacological profiling for clinical candidate selection.

AIM: To describe the biomarker strategy that was applied to select survodutide (BI 456906), BI 456908 and BI 456897 from 19 dual glucagon receptor (GCGR)/ glucagon-like peptide-1 receptor (GLP-1R) agonists for in-depth pharmacological profiling, which led to the qualification of survodutide as the clinical development candidate. MATERIALS AND METHODS: Potencies to increase cyclic adenosine monophosphate (cAMP) were determined in Chinese hamster ovary (CHO)-K1 cells stably expressing human GCGR and GLP-1R. Agonism for endogenously expressed receptors was investigated in insulinoma cells (MIN6) for mouse GLP-1R, and in rat primary hepatocytes for the GCGR. In vivo potencies to engage the GLP-1R or GCGR were determined, measuring improvement in oral glucose tolerance (30 nmol/kg) and increase in plasma fibroblast growth factor-21 (FGF21) and liver nicotinamide N-methyltransferase (NNMT) mRNA expression (100 nmol/kg), respectively. Body weight- and glucose-lowering efficacies were investigated in diet-induced obese (DIO) mice and diabetic db/db mice, respectively. RESULTS: Upon acute dosing in lean mice, target engagement biomarkers for the GCGR and GLP-1R demonstrated a significant correlation (Spearman correlation coefficient with p < 0.05) to the in vitro GCGR and GLP-1R potencies for the 19 dual agonists investigated. Survodutide, BI 456908 and BI 456897 were selected for in-depth pharmacological profiling based on the significant improvement in acute oral glucose tolerance achieved (area under the curve [AUC] of 54%, 57% and 60% vs. vehicle) that was comparable to semaglutide (AUC of 45% vs. vehicle), while showing different degrees of in vivo GCGR engagement, as determined by hepatic NNMT mRNA expression (increased by 15- to 17-fold vs. vehicle) and plasma FGF21 concentrations (increased by up to sevenfold vs. vehicle). In DIO mice, survodutide (30 nmol/kg/once daily), BI 456908 (30 nmol/kg/once daily) and BI 456897 (10 nmol/kg/once daily) achieved a body weight-lowering efficacy from baseline of 25%, 27% and 26%, respectively. In db/db mice, survodutide and BI 456908 (10 and 20 nmol/kg/once daily) significantly lowered glycated haemoglobin (0.4%-0.6%); no significant effect was observed for BI 456897 (3 and 7 nmol/kg/once daily). CONCLUSIONS: Survodutide was selected as the clinical candidate based on its balanced dual GCGR/GLP-1R pharmacology, engaging the GCGR for robust body weight-lowering efficacy exceeding that of selective GLP-1R agonists, while achieving antidiabetic efficacy that was comparable to selective GLP-1R agonism. Survodutide is currently being investigated in Phase 3 clinical trials in people living with obesity.

BI-Y, an Neuropilin-1 Antagonist, Enhances Revascularization and Prevents Vascular Endothelial Growth Factor-A Induced Retinal Hyperpermeability in Rodent Models of Retinopathies.

Diabetic retinopathy (DR) is a leading cause of vision loss in working-age adults. Despite an established standard of care for advanced forms of DR, some patients continue to lose vision after treatment. This may be due to the development of diabetic macular ischemia (DMI), which has no approved treatment. Neuropilin-1 (Nrp-1) is a coreceptor with two ligand-binding domains, with semaphorin-3A (Sema3A) binding to the A-domain and vascular endothelial growth factor-A (VEGF-A) binding to the B-domain. Sema3A directs a subset of neuronal growth cones as well as blood vessel growth by repulsion; when bound to Nrp-1, VEGF-A mediates vascular permeability and angiogenesis. Modulating Nrp-1 could therefore address multiple complications arising from DR, such as diabetic macular edema (DME) and DMI. BI-Y is a monoclonal antibody that binds to the Nrp-1 A-domain, antagonizing the effects of the ligand Sema3A and inhibiting VEGF-A-induced vascular permeability. This series of in vitro and in vivo studies examined the binding kinetics of BI-Y to Nrp-1 with and without VEGF-A165, the effect of BI-Y on Sema3A-induced cytoskeletal collapse, the effect of BI-Y on VEGF- A165-induced angiogenesis, neovascularization, cell integrity loss and permeability, and retinal revascularization. The data show that BI-Y binds to Nrp-1 and inhibits Sema3A-induced cytoskeletal collapse in vitro, may enhance revascularization of ischemic areas in an oxygen-induced retinopathy mouse model, and prevents VEGF-A-induced retinal hyperpermeability in rats. However, BI-Y does not interfere with VEGF-A-dependent choroidal neovascularization. These results support further investigation of BI-Y as a potential treatment for DMI and DME. SIGNIFICANCE STATEMENT: Diabetic macular ischemia (DMI) is a complication of diabetic retinopathy (DR) with no approved pharmacological treatment. Diabetic macular edema (DME) commonly co-occurs with DMI in patients with DR. This series of preclinical studies in mouse and rat models shows that neuropilin-1 antagonist BI-Y may enhance the revascularization of ischemic areas and prevents vascular endothelial growth factor-A (VEGF-A)-induced retinal hyperpermeability without affecting VEGF-A-dependent choroidal neovascularization; thus, BI-Y may be of interest as a potential treatment for patients with DR.

Collection of triatomines from sylvatic habitats by a Trypanosoma cruzi-infected scent detection dog in Texas, USA.

BACKGROUND: Triatomine insects, vectors of the etiologic agent of Chagas disease (Trypanosoma cruzi), are challenging to locate in sylvatic habitats. Collection techniques used in the United States often rely on methods to intercept seasonally dispersing adults or on community scientists' encounters. Neither method is suited for detecting nest habitats likely to harbor triatomines, which is important for vector surveillance and control. Furthermore, manual inspection of suspected harborages is difficult and unlikely to reveal novel locations and host associations. Similar to a team that used a trained dog to detect sylvatic triatomines in Paraguay, we worked with a trained scent detection dog to detect triatomines in sylvatic locations across Texas. PRINCIPLE METHODOLOGY/FINDINGS: Ziza, a 3-year-old German Shorthaired Pointer previously naturally infected with T. cruzi, was trained to detect triatomines. Over the course of 6 weeks in the fall of 2017, the dog and her handler searched at 17 sites across Texas. The dog detected 60 triatomines at 6 sites; an additional 50 triatomines were contemporaneously collected at 1 of these sites and 2 additional sites without the assistance of the dog. Approximately 0.98 triatomines per hour were found when only humans were conducting searches; when working with the dog, approximately 1.71 triatomines per hour were found. In total, 3 adults and 107 nymphs of four species (Triatoma gerstaeckeri, Triatoma protracta, Triatoma sanguisuga, and Triatoma indictiva) were collected. PCR testing of a subset revealed T. cruzi infection, including DTUs TcI and TcIV, in 27% of nymphs (n = 103) and 66% of adults (n = 3). Bloodmeal analysis of a subset of triatomines (n = 5) revealed feeding on Virginia opossum (Didelphis virginiana), Southern plains woodrat (Neotoma micropus), and eastern cottontail (Sylvilagus floridanus). CONCLUSION/SIGNIFICANCE: A trained scent detection dog enhanced triatomine detections in sylvatic habitats. This approach is effective at detecting nidicolous triatomines. Control of sylvatic sources of triatomines is challenging, but this new knowledge of specific sylvatic habitats and key hosts may reveal opportunities for novel vector control methods to block the transmission of T. cruzi to humans and domestic animals.

BI 456906: Discovery and preclinical pharmacology of a novel GCGR/GLP-1R dual agonist with robust anti-obesity efficacy.

OBJECTIVE: Obesity and its associated comorbidities represent a global health challenge with a need for well-tolerated, effective, and mechanistically diverse pharmaceutical interventions. Oxyntomodulin is a gut peptide that activates the glucagon receptor (GCGR) and glucagon-like peptide-1 receptor (GLP-1R) and reduces bodyweight by increasing energy expenditure and reducing energy intake in humans. Here we describe the pharmacological profile of the novel glucagon receptor (GCGR)/GLP-1 receptor (GLP-1R) dual agonist BI 456906. METHODS: BI 456906 was characterized using cell-based in vitro assays to determine functional agonism. In vivo pharmacological studies were performed using acute and subchronic dosing regimens to demonstrate target engagement for the GCGR and GLP-1R, and weight lowering efficacy. RESULTS: BI 456906 is a potent, acylated peptide containing a C18 fatty acid as a half-life extending principle to support once-weekly dosing in humans. Pharmacological doses of BI 456906 provided greater bodyweight reductions in mice compared with maximally effective doses of the GLP-1R agonist semaglutide. BI 456906's superior efficacy is the consequence of increased energy expenditure and reduced food intake. Engagement of both receptors in vivo was demonstrated via glucose tolerance, food intake, and gastric emptying tests for the GLP-1R, and liver nicotinamide N-methyltransferase mRNA expression and circulating biomarkers (amino acids, fibroblast growth factor-21) for the GCGR. The dual activity of BI 456906 at the GLP-1R and GCGR was supported using GLP-1R knockout and transgenic reporter mice, and an ex vivo bioactivity assay. CONCLUSIONS: BI 456906 is a potent GCGR/GLP-1R dual agonist with robust anti-obesity efficacy achieved by increasing energy expenditure and decreasing food intake.

Efficacy of an Anti-Semaphorin 3A Neutralizing Antibody in a Male Experimental Retinal Vein Occlusion Mouse Model.

Purpose: Semaphorin 3A (Sema3A) is a promising therapeutic target for macular edema in age-related macular degeneration, diabetic retinopathy, and retinal vein occlusion (RVO). Anti-vascular endothelial growth factors (anti-VEGFs) are the current standard of care for many retinal diseases. This study investigated the Sema3A neutralizing antibody BI-X and/or anti-VEGF therapy (aflibercept) in an RVO mouse model. Treatment efficacy was examined and grouped by timing subsequent to the RVO mouse model induction: efficacy against the onset of intraretinal edema 1 day postinduction and protective effects at 7 days postinduction. Methods: We examined the changes in expression of Sema3A in the retina of an RVO mouse model. In addition, changes in expression of tumor necrosis factor (TNF)-α and semaphorin-related proteins (neuropilin-1 and plexin A1) in the retina upon treatment were analyzed by Western blotting. The effects of BI-X and/or aflibercept were evaluated using measures of retinal edema, blood flow, and thinning of the inner nuclear layer. Results: Induction of vein occlusion in the RVO mouse model significantly increased Sema3A expression in the retina, particularly in the inner nuclear layer. BI-X was effective as a monotherapy and in combination with anti-VEGF therapy, demonstrating a beneficial effect on intraretinal edema and retinal blood flow. Moreover, in the RVO mouse model, BI-X monotherapy normalized the changes in expression of TNF-α and semaphorin-related proteins. Conclusions: These findings support targeting Sema3A to treat intraretinal edema and retinal ischemia.

Sema3A Antibody BI-X Prevents Cell Permeability and Cytoskeletal Collapse in HRMECs and Increases Tip Cell Density in Mouse Oxygen-Induced Retinopathy.

Purpose: Semaphorin 3A (Sema3A) is an axonal guidance molecule that inhibits angiogenesis by vasorepulsion and blocks revascularization in the ischemic retina. BI-X is an intravitreal anti-Sema3A agent under clinical investigation in patients with proliferative diabetic retinopathy (PDR) and diabetic macular ischemia (DMI). Methods: Surface plasmon resonance was used to determine binding affinity of BI-X to human and murine Sema3A. In vitro, human retinal microvascular endothelial cells (HRMECs) were used to assess effects of BI-X on cell permeability and cytoskeletal collapse induced by Sema3A. In vivo, intravitreal BI-X or an anti-trinitrophenol control antibody was administered in both eyes in mice with oxygen-induced retinopathy (OIR). Retinal flat mounts were prepared, and avascular area and tip cell density were determined using confocal laser-scanning microscopy. Results: Dissociation constants for BI-X binding to human and murine Sema3A were 29 pM and 27 pM, respectively. In vitro, BI-X prevented HRMEC permeability and cytoskeletal collapse induced by Sema3A. In vivo, BI-X increased tip cell density by 33% (P < 0.001) and reduced avascular area by 12% (not significant). A significant negative correlation was evident between avascular area and tip cell density (r2 = 0.4205, P < 0.0001). Conclusions: BI-X binds to human Sema3A with picomolar affinity and prevents cell permeability and cytoskeletal collapse in HRMECs. BI-X also enhances revascularization in mice with OIR. Translational Relevance: BI-X is a potent inhibitor of human Sema3A that improves revascularization in a murine model of OIR; BI-X is currently being investigated in patients with laser-treated PDR and DMI.

Deaths Among U.S. Air Force Basic Military Trainees, 2008-2020.

INTRODUCTION: The U.S. Air Force (USAF) Basic Military Training (BMT), a rigorous training program for all enlisted members of the USAF, trains roughly 36,000 recruits annually. Transforming civilians into ready warrior airmen has inherent risks to trainee health, which has infrequently included death. While the average death rate at USAF BMT has decreased between 1956 and 2007 due to process improvement and preventive medicine efforts, further review is warranted to examine the deaths that have occurred since the last published period (1997-2007) and to determine the impact policy changes and updates have had on death rates since that time. Therefore, the purpose of this paper is to identify death rates and types from 2008 to 2020, explore policy implementation, and identify areas needing further improvement or modifications to the overall safety, fitness, and health of USAF BMT trainees. MATERIALS AND METHODS: All deaths were examined and reviewed from 2008 through 2020 for trainees attending the USAF BMT using medical records and autopsy reports. Death rates were calculated using the total population of trainees in a given year as well as over the entire 13-year study period. RESULTS: From 2008 to 2020, five deaths occurred among USAF BMT trainees (one cardiac, two exertional sickling due to sickle cell trait, one infection, and one suicide). This resulted in an overall average death rate of 1.08 per 100,000 trainees, as compared to 1.46 per 100,000 from 1997 to 2007. The last death in the study period occurred in 2016. CONCLUSION: A modest downward trend of average death rate has continued since 2007, and no deaths from 2016 through 2020 represents the longest time frame without any deaths at USAF BMT over all times reported (dating back to 1956) which suggest that emergency best practice policies are/have improved. However, cardiac death rate and suicide rate have not changed since the last report. Policies and practices should be continuously reviewed and refined to reduce the risk of death at USAF BMT.

Deep Learning-Based Detection of Endothelial Tip Cells in the Oxygen-Induced Retinopathy Model.

Proliferative retinopathies, such as diabetic retinopathy and retinopathy of prematurity, are leading causes of vision impairment. A common feature is a loss of retinal capillary vessels resulting in hypoxia and neuronal damage. The oxygen-induced retinopathy model is widely used to study revascularization of an ischemic area in the mouse retina. The presence of endothelial tip cells indicates vascular recovery; however, their quantification relies on manual counting in microscopy images of retinal flat mount preparations. Recent advances in deep neural networks (DNNs) allow the automation of such tasks. We demonstrate a workflow for detection of tip cells in retinal images using the DNN-based Single Shot Detector (SSD). The SSD was designed for detection of objects in natural images. We adapt the SSD architecture and training procedure to the tip cell detection task and retrain the DNN using labeled tip cells in images of fluorescently stained retina flat mounts. Transferring knowledge from the pretrained DNN and extensive data augmentation reduced the amount of required labeled data. Our system shows a performance comparable to the human level, while providing highly consistent results. Therefore, such a system can automate counting of tip cells, a readout frequently used in retinopathy research, thereby reducing routine work for biomedical experts.

Outcomes of Embedded Athletic Training Services Within United States Air Force Basic Military Training.

CONTEXT: Musculoskeletal injury is the leading cause of attrition from military training. OBJECTIVE: To assess the effect of an embedded athletic training musculoskeletal care model within a basic military training unit. DESIGN: Cluster randomized trial. SETTING: United States Air Force Basic Military Training, Joint Base San Antonio-Lackland. PATIENTS OR OTHER PARTICIPANTS: Military recruits randomly assigned to 1 of 3 training squadrons, 2 control and 1 experimental, between January 2016 and December 2018. INTERVENTION(S): A sports medicine care model was established in 1 squadron by embedding 2 certified athletic trainers overseen by a sports medicine fellowship-trained physician. The athletic trainers diagnosed and coordinated rehabilitation as the primary point of contact for recruits and developed interventions with medical and military leadership based on injury trends. MAIN OUTCOME MEASURE(S): Recruit attrition from basic training due to a musculoskeletal injury. Secondary outcomes were all-cause attrition, on-time graduation, rates of lower extremity injury and stress fracture, rates of specialty care appointments, and fiscal costs. RESULTS: Recruits in the athletic training musculoskeletal care arm experienced 25% lower musculoskeletal-related attrition (risk ratio = 0.75 [95% CI = 0.64, 0.89]) and 15% lower all-cause attrition (risk ratio = 0.85 [95% CI = 0.80, 0.91]), translating to a net saving of more than $10 million. The intervention reduced the incidence of lower extremity stress fracture by 16% (rate ratio = 0.84 [95% CI = 0.73, 0.97]). CONCLUSIONS: An embedded athletic training musculoskeletal care model outperformed usual care across operational, medical, and fiscal outcomes.

Can the detection dog alert on COVID-19 positive persons by sniffing axillary sweat samples? A proof-of-concept study.

The aim of this proof-of-concept study was to evaluate if trained dogs could discriminate between sweat samples from symptomatic COVID-19 positive individuals (SARS-CoV-2 PCR positive) and those from asymptomatic COVID-19 negative individuals. The study was conducted at 2 sites (Paris, France, and Beirut, Lebanon), followed the same training and testing protocols, and involved six detection dogs (three explosive detection dogs, one search and rescue dog, and two colon cancer detection dogs). A total of 177 individuals were recruited for the study (95 symptomatic COVID-19 positive and 82 asymptomatic COVID-19 negative individuals) from five hospitals, and one underarm sweat sample per individual was collected. The dog training sessions lasted between one and three weeks. Once trained, the dog had to mark the COVID-19 positive sample randomly placed behind one of three or four olfactory cones (the other cones contained at least one COVID-19 negative sample and between zero and two mocks). During the testing session, a COVID-19 positive sample could be used up to a maximum of three times for one dog. The dog and its handler were both blinded to the COVID-positive sample location. The success rate per dog (i.e., the number of correct indications divided by the number of trials) ranged from 76% to 100%. The lower bound of the 95% confidence interval of the estimated success rate was most of the time higher than the success rate obtained by chance after removing the number of mocks from calculations. These results provide some evidence that detection dogs may be able to discriminate between sweat samples from symptomatic COVID-19 individuals and those from asymptomatic COVID-19 negative individuals. However, due to the limitations of this proof-of-concept study (including using some COVID-19 samples more than once and potential confounding biases), these results must be confirmed in validation studies.

An RNA-Seq atlas of gene expression in mouse and rat normal tissues.

Gene functionality is closely connected to its expression specificity across tissues and cell types. RNA-Seq is a powerful quantitative tool to explore genome wide expression. The aim of this study is to provide a comprehensive RNA-Seq dataset across the same 13 tissues for mouse and rat, two of the most relevant species for biomedical research. The dataset provides the transcriptome across tissues from three male C57BL6 mice and three male Han Wistar rats. We also describe our bioinformatics pipeline to process and technically validate the data. Principal component analysis shows that tissue samples from both species cluster similarly. We show by comparative genomics that many genes with high sequence identity with respect to their human orthologues also have a highly correlated tissue distribution profile and are in agreement with manually curated literature data for human. In summary, the present study provides a unique resource for comparative genomics and will facilitate the analysis of tissue specificity and cross-species conservation in higher organisms.

Design, synthesis and evaluation of MCH receptor 1 antagonists--Part III: Discovery of pre-clinical development candidate BI 186908.

Although overweight and obesity are highly prevalent conditions, options to treat them are still very limited. As part of our search for safe and effective MCH-R1 antagonists for the treatment of obesity, two series of pyridones and pyridazinones were evaluated. Optimization was aimed at improving DMPK properties by increasing metabolic stability and improving the safety profile by reducing inhibition of the hERG channel and reducing the potential to induce phospholipidosis. Steric shielding of a labile keto moiety with an ortho-methyl group and fine-tuning of the polarity in several parts of the molecule resulted in BI 186908 (11 g), a potent and selective MCH-R1 antagonist with favorable DMPK and CMC properties. Chronic administration of BI 186908 resulted in significant body weight reduction comparable to sibutramine in a 4 week diet-induced obesity model in rats. Based on its favorable safety profile, BI 186908 was advanced to pre-clinical development.

Design, synthesis and evaluation of MCH receptor 1 antagonists--Part II: Optimization of pyridazines toward reduced phospholipidosis and hERG inhibition.

Despite recent success there remains a high therapeutic need for the development of drugs targeting diseases associated with the metabolic syndrome. As part of our search for safe and effective MCH-R1 antagonists for the treatment of obesity, a series of 3,6-disubstituted pyridazines was evaluated. During optimization several issues of the initial lead structures had to be resolved, such as selectivity over related GPCRs, inhibition of the hERG channel as well as the potential to induce phospholipidosis. Utilizing property-based design, we could demonstrate that all parameters can significantly be improved by consequently increasing the polarity of the compounds. By this strategy, we succeeded in identifying potent and orally available MCH-R1 antagonists with good selectivity over M1 and 5-HT2A and an improved safety profile with respect to hERG inhibition and phospholipidosis.

Linagliptin improves insulin sensitivity and hepatic steatosis in diet-induced obesity.

Linagliptin (TRADJENTA™) is a selective dipeptidyl peptidase-4 (DPP-4) inhibitor. DPP-4 inhibition attenuates insulin resistance and improves peripheral glucose utilization in humans. However, the effects of chronic DPP-4 inhibition on insulin sensitivity are not known. The effects of long-term treatment (3-4 weeks) with 3 mg/kg/day or 30 mg/kg/day linagliptin on insulin sensitivity and liver fat content were determined in diet-induced obese C57BL/6 mice. Chow-fed animals served as controls. DPP-4 activity was significantly inhibited (67-89%) by linagliptin (P<0.001). Following an oral glucose tolerance test, blood glucose concentrations (measured as area under the curve) were significantly suppressed after treatment with 3 mg/kg/day (-16.5% to -20.3%; P<0.01) or 30 mg/kg/day (-14.5% to -26.4%; P<0.05) linagliptin (both P<0.01). Liver fat content was significantly reduced by linagliptin in a dose-dependent manner (both doses P<0.001). Diet-induced obese mice treated for 4 weeks with 3 mg/kg/day or 30 mg/kg/day linagliptin had significantly improved glycated hemoglobin compared with vehicle (both P<0.001). Significant dose-dependent improvements in glucose disposal rates were observed during the steady state of the euglycemic-hyperinsulinemic clamp: 27.3 mg/kg/minute and 32.2 mg/kg/minute in the 3 mg/kg/day and 30 mg/kg/day linagliptin groups, respectively; compared with 20.9 mg/kg/minute with vehicle (P<0.001). Hepatic glucose production was significantly suppressed during the clamp: 4.7 mg/kg/minute and 2.1 mg/kg/minute in the 3 mg/kg/day and 30 mg/kg/day linagliptin groups, respectively; compared with 12.5 mg/kg/minute with vehicle (P<0.001). In addition, 30 mg/kg/day linagliptin treatment resulted in a significantly reduced number of macrophages infiltrating adipose tissue (P<0.05). Linagliptin treatment also decreased liver expression of PTP1B, SOCS3, SREBP1c, SCD-1 and FAS (P<0.05). Other tissues like muscle, heart and kidney were not significantly affected by the insulin sensitizing effect of linagliptin. Long-term linagliptin treatment reduced liver fat content in animals with diet-induced hepatic steatosis and insulin resistance, and may account for improved insulin sensitivity.

Retrospective case series of five nontraumatic deaths among U.S. Air Force basic military trainees (1997-2007).

INTRODUCTION: Basic military training is both physically and mentally demanding. New recruits represent a young and relatively healthy subpopulation of individuals, and premature mortality is rare. The purpose of this retrospective case series is to discuss the causes of nontraumatic deaths among U.S. Air Force Basic Military Trainees (BMTs) at Lackland Air Force Base in San Antonio, Texas. STUDY OBJECTIVE: The study objective is to describe the demographic, environmental, and clinical factors associated with nontraumatic deaths among BMTs. METHODS: Data were extracted from medical records and autopsy reports. RESULTS: During the time period of 1997 to 2007, there were 5 nontraumatic deaths. CONCLUSION: Implementation of new policies or revisions to existing policies has reduced the number of nontraumatic deaths in the U.S. Air Force BMT population.

Acetyl-CoA carboxylases 1 and 2 show distinct expression patterns in rats and humans and alterations in obesity and diabetes.

BACKGROUND: Acetyl-CoA carboxylases (ACC) 1 and 2 are central enzymes in lipid metabolism. To further investigate their relevance for the development of obesity and type 2 diabetes, expression of both ACC isoforms was analyzed in obese fa/fa Zucker fatty and Zucker diabetic fatty rats at different ages in comparison to Zucker lean controls. METHODS: ACC1 and ACC2 transcript levels were measured by quantitative real-time polymerase chain reaction in metabolically relevant tissues of Zucker fatty, Zucker diabetic fatty and Zucker lean control animals. Quantitative real-time polymerase chain reaction was also applied to measure ACC tissue distribution in human tissues. For confirmation on a protein level, quantitative mass spectrometry was used. RESULTS: Disease-related transcriptional changes of both ACC isoforms were observed in various tissues of Zucker fatty and Zucker diabetic fatty rats including liver, pancreas and muscle. Changes were most prominent in oxidative tissues of diabetic rats, where ACC2 was significantly increased and ACC1 was reduced compared with Zucker lean control animals. A comparison of the overall tissue distribution of both ACC isoforms in humans and rats surprisingly revealed strong differences. While in rats ACC1 was mainly expressed in lipogenic and ACC2 in oxidative tissues, ACC2 was predominant in oxidative and lipogenic tissues in humans. CONCLUSION: Our data support a potential role for both ACC isoforms in the development of obesity and diabetes in rats. However, the finding of fundamental species differences in ACC1 and ACC2 tissue expression might be indicative for different functions of both isoforms in humans and rats and raises the question to which degree these models are predictive for the physiology and pathophysiology of lipid metabolism in humans.

Chronic treatment with the dipeptidyl peptidase-4 inhibitor BI 1356 [(R)-8-(3-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione] increases basal glucagon-like peptide-1 and improves glycemic control in diabetic rodent models.

Antidiabetic effects of dipeptidyl peptidase-4 (DPP-4) inhibitors are exerted by potentiation of the biological activity of incretin hormones like glucagon-like peptide (GLP)-1. BI 1356 [proposed trade name Ondero; (R)-8-(3-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione] is a novel competitive, selective, potent, and long-acting DPP-4 inhibitor under clinical development for the treatment of type 2 diabetes. The effect of 1 to 2 months of chronic dosing of BI 1356 in two different animal models was investigated. The first is a primarily genetic model (Zucker diabetic fatty rats), and the second is a nongenetic model (mice with diabetes induced by a combination of high-fat diet and low-dose streptozotocin). BI 1356 was shown to lower HbA1c after multiple dosing in both models. The improvement of glycemic control achieved in disease models of different etiology suggests that BI 1356 would also be efficacious in treating a broad spectrum of type 2 diabetic patients. In addition, multiple dosing of BI 1356 leads to a sustained increase in basal levels of active GLP-1 in the systemic circulation, with expected long-term benefits on pancreatic alpha- and beta-cells. The effects on HbA1c and GLP-1 were superior to the short-acting DPP-4 inhibitor vildagliptin, demonstrating the potential of BI 1356 as a once daily treatment for type 2 diabetes at low therapeutic doses.

3,5-Dihydro-imidazo[4,5-d]pyridazin-4-ones: a class of potent DPP-4 inhibitors.

Systematic variations of the xanthine scaffold in close analogs of development compound BI 1356 led to the class of 3,5-dihydro-imidazo[4,5-d]pyridazin-4-ones which provided, after substituent screening, a series of highly potent DPP-4 inhibitors.

(R)-8-(3-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione (BI 1356), a novel xanthine-based dipeptidyl peptidase 4 inhibitor, has a superior potency and longer duration of action compared with other dipeptidyl peptidase-4 inhibitors.

BI 1356 [proposed trade name ONDERO; (R)-8-(3-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione] is a novel dipeptidyl peptidase (DPP)-4 inhibitor under clinical development for the treatment of type 2 diabetes. In this study, we investigated the potency, selectivity, mechanism, and duration of action of BI 1356 in vitro and in vivo and compared it with other DPP-4 inhibitors. BI 1356 inhibited DPP-4 activity in vitro with an IC(50) of approximately 1 nM, compared with sitagliptin (19 nM), alogliptin (24 nM), saxagliptin (50 nM), and vildagliptin (62 nM). BI 1356 was a competitive inhibitor, with a K(i) of 1 nM. The calculated k(off) rate for BI 1356 was 3.0 x 10(-5)/s (versus 2.1 x 10(-4)/s for vildagliptin). BI 1356 was >/=10,000-fold more selective for DPP-4 than DPP-8, DPP-9, amino-peptidases N and P, prolyloligopeptidase, trypsin, plasmin, and thrombin and was 90-fold more selective than for fibroblast activation protein in vitro. In HanWistar rats, the DPP-4 inhibition 24 h after administration of BI 1356 was more profound than with any of the other DPP-4 inhibitors. In C57BL/6J mice and Zucker fatty (fa/fa) rats, the duration of action on glucose tolerance decreased in the order BI 1356 > (sitagliptin/saxagliptin) > vildagliptin. These effects were mediated through control of glucagon-like peptide-1 and insulin. In conclusion, BI 1356 inhibited DPP-4 more effectively than vildagliptin, sitagliptin, saxagliptin, and alogliptin and has the potential to become the first truly once-a-day DPP-4 inhibitor for the treatment of type 2 diabetes.