Hematopoietic-Derived Galectin-3 Causes Cellular and Systemic Insulin Resistance.

In obesity, macrophages and other immune cells accumulate in insulin target tissues, promoting a chronic inflammatory state and insulin resistance. Galectin-3 (Gal3), a lectin mainly secreted by macrophages, is elevated in both obese subjects and mice. Administration of Gal3 to mice causes insulin resistance and glucose intolerance, whereas inhibition of Gal3, through either genetic or pharmacologic loss of function, improved insulin sensitivity in obese mice. In vitro treatment with Gal3 directly enhanced macrophage chemotaxis, reduced insulin-stimulated glucose uptake in myocytes and 3T3-L1 adipocytes and impaired insulin-mediated suppression of glucose output in primary mouse hepatocytes. Importantly, we found that Gal3 can bind directly to the insulin receptor (IR) and inhibit downstream IR signaling. These observations elucidate a novel role for Gal3 in hepatocyte, adipocyte, and myocyte insulin resistance, suggesting that Gal3 can link inflammation to decreased insulin sensitivity. Inhibition of Gal3 could be a new approach to treat insulin resistance.

Detection and measurements of apical lesions in the upper jaw by cone beam computed tomography and panoramic radiography as a function of cortical bone thickness.

OBJECTIVES: In the current literature, cone beam computed tomography (CBCT) seems to be more accurate in detecting apical lesions (AL) than two-dimensional radiographs. Cortical bone thickness might have an influence on AL visibility. Therefore, the purpose of the study was to directly compare the diagnostic accuracy of panoramic radiography (PANO) and CBCT in detecting AL in the upper jaw and determine the influence of cortical bone thickness on AL visibility. MATERIALS AND METHODS: Anonymised digital images of 351 patients who received a CBCT image and a panoramic radiograph within 90 days were examined for AL in the upper jaw. The analysis was conducted by a trained examiner and reviewed by an expert in dental radiology. Further, the dimensions of AL and cortical bone thickness in the region affected by AL were measured to determine their influence on visibility. Statistical analysis was carried out by means of statistical software (IBM SPSS 25; Armonk, NY, USA). RESULTS: The mean age of the patients was 58.9 years with an almost equal gender distribution. A total of 2223 teeth in the upper jaw were included in the final analysis. CBCT detected AL on 144 teeth (6.5%), of which only 23 were also visible on a PANO. The difference between both methods was significant (p < 0.001). The dimensions of AL measured within a PANO were approximately twice as high as those measured by CBCT. However, the difference was not significant (p ≥ 0.005). Cortical bone thickness had no influence on AL visibility. CONCLUSIONS AND CLINICAL RELEVANCE: Panoramic radiographs are unsuitable for a reliable diagnosis of AL in the upper jaw, while CBCT leads to a better visualisation of AL. Bone thickness has no significant influence on AL visibility with either imaging method.

Transfer accuracy of two indirect bonding techniques-an in vitro study with 3D scanned models.

Background and objectives: Indirect bonding (IDB) proved to be an effective method for appropriate bracket positioning in patients. Different methods and materials are available for fabricating transfer trays. This in vitro study was designed to measure and compare the transfer accuracy of two common IDB methods. Materials and methods: Sixty stone models were fabricated and separated in two groups of 30 models each (15 working models, 15 patient models). After placing brackets on the working models, 30 IDB trays were made: 15 silicone (method I) and 15 double-vacuum forms (method II). With these trays, the brackets were transferred to the patient models. The bracket positions were scanned before and after the IDB procedure with an intraoral scanner. The linear and angular discrepancies were then determined digitally by measuring six different dimensions: occluso-cervical, mesio-distal, bucco-lingual, tip, rotation, and torque. Results: The silicone trays showed fewer transfer discrepancies, on average, in all measured dimensions. There were significant differences between the methods in the occluso-cervical (P < 0.001), mesio-distal (P = 0.001), and torque (P = 0.044) dimensions. With both methods, 100 per cent of the horizontal and transversal measurements of both methods were within the clinically acceptable range of 0.25 mm. With method I, 98.5 per cent of the vertical and 95.9 per cent of the angular measurements were within the range of 0.25 mm and 1°, respectively. With method II, 94 per cent of the vertical and 84.8 per cent of the angular measurements were within the clinically acceptable range. Conclusions: Although both transfer methods showed a high precision, silicone trays scored better in terms of accuracy than double-vacuum forms.

Genetic Algorithm-Based Model Order Reduction of Aeroservoelastic Systems with Consistent States.

This paper presents a model order reduction framework to construct linear parameter-varying reduced-order models of flexible aircraft for aeroservoelasticity analysis and control synthesis in broad two-dimensional flight parameter space. Genetic algorithms are used to automatically determine physical states for reduction and to generate reduced-order models at grid points within parameter space while minimizing the trial-and-error process. In addition, balanced truncation for unstable systems is used in conjunction with the congruence transformation technique to achieve locally optimal realization and "weak" fulfillment of state consistency across the entire parameter space. Therefore, aeroservoelasticity reduced-order models at any flight condition can be obtained simply through model interpolation. The methodology is applied to the pitch-plant model of the X-56A Multi-Use Technology Testbed currently being tested at NASA Armstrong Flight Research Center for flutter suppression and gust load alleviation. The present studies indicate that the reduced-order model with more than 12× reduction in the number of states relative to the original model is able to accurately predict system response among all input-output channels. The genetic-algorithm-guided approach exceeds manual and empirical state selection in terms of efficiency and accuracy. The interpolated aeroservoelasticity reduced-order models exhibit smooth pole transition and continuously varying gains along a set of prescribed flight conditions, which verifies consistent state representation obtained by congruence transformation. The present model order reduction framework can be used by control engineers for robust aeroservoelasticity controller synthesis and novel vehicle design.

Sulforaphane impedes mitochondrial reprogramming and histone acetylation in polarizing M1 (LPS) macrophages.

M1 (LPS) macrophages are characterized by a high expression of pro-inflammatory mediators, and distinct metabolic features that comprise increased glycolysis, a broken TCA cycle, or impaired OXPHOS with augmented mitochondrial ROS production. This study investigated whether the phytochemical sulforaphane (Sfn) influences mitochondrial reprogramming during M1 polarization, as well as to what extent this can contribute to Sfn-mediated inhibition of M1 marker expression in murine macrophages. The use of extracellular flux-, metabolite-, and immunoblot analyses as well as fluorescent dyes indicative for mitochondrial morphology, membrane potential or superoxide production, demonstrated that M1 (LPS/Sfn) macrophages maintain an unbroken TCA cycle, higher OXPHOS rate, boosted fusion dynamics, lower membrane potential, and less superoxide production in their mitochondria when compared to control M1 (LPS) cells. Sustained OXPHOS and TCA activity but not the concomitantly observed high dependency on fatty acids as fuel appeared necessary for M1 (LPS/Sfn) macrophages to reduce expression of nos2, il1ß, il6 and tnfα. M1 (LPS/Sfn) macrophages also displayed lower nucleo/cytosolic acetyl-CoA levels in association with lower global and site-specific histone acetylation at selected pro-inflammatory gene promoters than M1 (LPS), evident in colorimetric coupled enzyme assays, immunoblot and ChIP-qPCR analyses, respectively. Supplementation with acetate or citrate was able to rescue both histone acetylation and mRNA expression of the investigated M1 marker genes in Sfn-treated cells. Overall, Sfn preserves mitochondrial functionality and restricts indispensable nuclear acetyl-CoA for histone acetylation and M1 marker expression in LPS-stimulated macrophages.

Corrigendum: Sulforaphane diminishes moonlighting of pyruvate kinase M2 and interleukin 1ß expression in M1 (LPS) macrophages.

[This corrects the article DOI: 10.3389/fimmu.2022.935692.].

Ectonucleotidase NTPDase3 is abundant in pancreatic ß-cells and regulates glucose-induced insulin secretion.

Extracellular ATP released from pancreatic ß-cells acts as a potent insulinotropic agent through activation of P2 purinergic receptors. Ectonucleotidases, a family of membrane-bound nucleotide-metabolizing enzymes, regulate extracellular ATP levels by degrading ATP and related nucleotides. Ectonucleotidase activity affects the relative proportion of ATP and its metabolites, which in turn will impact the level of purinergic receptor stimulation exerted by extracellular ATP. Therefore, we investigated the expression and role of ectonucleotidases in pancreatic ß-cells. Of the ectonucleotidases studied, only ENTPD3 (gene encoding the NTPDase3 enzyme) mRNA was detected at fairly abundant levels in human and mouse pancreatic islets as well as in insulin-secreting MIN6 cells. ARL67156, a selective ectonucleotidase inhibitor, blocked degradation of extracellular ATP that was added to MIN6 cells. The compound also decreased degradation of endogenous ATP released from cells. Measurements of insulin secretion in MIN6 cells as well as in mouse and human pancreatic islets demonstrated that ARL67156 potentiated glucose-dependent insulin secretion. Downregulation of NTPDase3 expression in MIN6 cells with the specific siRNA replicated the effects of ARL67156 on extracellular ATP hydrolysis and insulin secretion. Our results demonstrate that NTPDase3 is the major ectonucleotidase in pancreatic ß-cells in multiple species and that it modulates insulin secretion by controlling activation of purinergic receptors.

Norbergenin prevents LPS-induced inflammatory responses in macrophages through inhibiting NFκB, MAPK and STAT3 activation and blocking metabolic reprogramming.

Inflammation is thought to be a key cause of many chronic diseases and cancer. However, current therapeutic agents to control inflammation have limited long-term use potential due to various side-effects. This study aimed to examine the preventive effects of norbergenin, a constituent of traditional anti-inflammatory recipes, on LPS-induced proinflammatory signaling in macrophages and elucidate the underlying mechanisms by integrative metabolomics and shotgun label-free quantitative proteomics platforms. Using high-resolution mass spectrometry, we identified and quantified nearly 3000 proteins across all samples in each dataset. To interpret these datasets, we exploited the differentially expressed proteins and conducted statistical analyses. Accordingly, we found that LPS-induced production of NO, IL1ß, TNFα, IL6 and iNOS in macrophages was alleviated by norbergenin via suppressed activation of TLR2 mediated NFκB, MAPKs and STAT3 signaling pathways. In addition, norbergenin was capable of overcoming LPS-triggered metabolic reprogramming in macrophages and restrained the facilitated glycolysis, promoted OXPHOS, and restored the aberrant metabolites within the TCA cycle. This is linked to its modulation of metabolic enzymes to support its anti-inflammatory activity. Thus, our results uncover that norbergenin regulates inflammatory signaling cascades and metabolic reprogramming in LPS stimulated macrophages to exert its anti-inflammatory potential.

Metabolic support by macrophages sustains colonic epithelial homeostasis.

The intestinal epithelium has a high turnover rate and constantly renews itself through proliferation of intestinal crypt cells, which depends on insufficiently characterized signals from the microenvironment. Here, we showed that colonic macrophages were located directly adjacent to epithelial crypt cells in mice, where they metabolically supported epithelial cell proliferation in an mTORC1-dependent manner. Specifically, deletion of tuberous sclerosis complex 2 (Tsc2) in macrophages activated mTORC1 signaling that protected against colitis-induced intestinal damage and induced the synthesis of the polyamines spermidine and spermine. Epithelial cells ingested these polyamines and rewired their cellular metabolism to optimize proliferation and defense. Notably, spermine directly stimulated proliferation of colon epithelial cells and colon organoids. Genetic interference with polyamine production in macrophages altered global polyamine levels in the colon and modified epithelial cell proliferation. Our results suggest that macrophages act as "commensals" that provide metabolic support to promote efficient self-renewal of the colon epithelium.

Sulforaphane diminishes moonlighting of pyruvate kinase M2 and interleukin 1ß expression in M1 (LPS) macrophages.

Murine macrophages activated by the Toll-like receptor 4 agonist lipopolysaccharide (LPS) polarize to the M1 type by inducing proinflammatory marker proteins and changing their energy metabolism to increased aerobic glycolysis and reduced respiration. We here show that the aliphatic isothiocyanate sulforaphane (Sfn) diminishes M1 marker expression (IL-1ß, IL-6, TNF-α, iNOS, NO, and ROS) and leads to highly energetic cells characterized by both high glycolytic and high respiratory activity as assessed by extracellular flux analysis. Focusing on a potential connection between high glycolytic activity and low IL-1ß expression in M1 (LPS/Sfn) macrophages, we reveal that Sfn impedes the moonlighting function of pyruvate kinase M2 (PKM2) in M1 macrophages. Sfn limits mono/dimerization and nuclear residence of PKM2 accompanied by reduced HIF-1α levels, Stat3 phosphorylation at tyrosine 705, and IL-1ß expression while preserving high levels of cytosolic PKM2 tetramer with high glycolytic enzyme activity. Sfn prevents glutathionylation of PKM2 in LPS-stimulated macrophages which may account for the reduced loss of PKM2 tetramer. Overall, we uncover PKM2 as a novel affected hub within the anti-inflammatory activity profile of Sfn.

Branched-chain ketoacids derived from cancer cells modulate macrophage polarization and metabolic reprogramming.

Macrophages are prominent immune cells in the tumor microenvironment that can be educated into pro-tumoral phenotype by tumor cells to favor tumor growth and metastasis. The mechanisms that mediate a mutualistic relationship between tumor cells and macrophages remain poorly characterized. Here, we have shown in vitro that different human and murine cancer cell lines release branched-chain α-ketoacids (BCKAs) into the extracellular milieu, which influence macrophage polarization in an monocarboxylate transporter 1 (MCT1)-dependent manner. We found that α-ketoisocaproate (KIC) and α-keto-ß-methylvalerate (KMV) induced a pro-tumoral macrophage state, whereas α-ketoisovalerate (KIV) exerted a pro-inflammatory effect on macrophages. This process was further investigated by a combined metabolomics/proteomics platform. Uptake of KMV and KIC fueled macrophage tricarboxylic acid (TCA) cycle intermediates and increased polyamine metabolism. Proteomic and pathway analyses revealed that the three BCKAs, especially KMV, exhibited divergent effects on the inflammatory signal pathways, phagocytosis, apoptosis and redox balance. These findings uncover cancer-derived BCKAs as novel determinants for macrophage polarization with potential to be selectively exploited for optimizing antitumor immune responses.

A Potential Citrate Shunt in Erythrocytes of PKAN Patients Caused by Mutations in Pantothenate Kinase 2.

Pantothenate kinase-associated neurodegeneration (PKAN) is a progressive neurodegenerative disease caused by mutations in the pantothenate kinase 2 (PANK2) gene and associated with iron deposition in basal ganglia. Pantothenate kinase isoforms catalyze the first step in coenzyme A (CoA) biosynthesis. Since PANK2 is the only isoform in erythrocytes, these cells are an excellent ex vivo model to study the effect of PANK2 point mutations on expression/stability and activity of the protein as well as on the downstream molecular consequences. PKAN erythrocytes containing the T528M PANK2 mutant had residual enzyme activities but variable PANK2 abundances indicating an impaired regulation of the protein. Patients with G521R/G521R, G521R/G262R, and R264N/L275fs PANK2 mutants had no residual enzyme activity and strongly reduced PANK2 abundance. G521R inactivates the catalytic activity of the enzyme, whereas G262R and the R264N point mutations impair the switch from the inactive to the active conformation of the PANK2 dimer. Metabolites in cytosolic extracts were analyzed by gas chromatography-mass spectrometry and multivariate analytic methods revealing changes in the carboxylate metabolism of erythrocytes from PKAN patients as compared to that of the carrier and healthy control. Assuming low/absent CoA levels in PKAN erythrocytes, changes are consistent with a model of altered citrate channeling where citrate is preferentially converted to α-ketoglutarate and α-hydroxyglutarate instead of being used for de novo acetyl-CoA generation. This finding hints at the importance of carboxylate metabolism in PKAN pathology with potential links to reduced cytoplasmic acetyl-CoA levels in neurons and to aberrant brain iron regulation.

Root exudation of contrasting drought-stressed pearl millet genotypes conveys varying biological nitrification inhibition (BNI) activity.

Roots secrete a vast array of low molecular weight compounds into the soil broadly referred to as root exudates. It is a key mechanism by which plants and soil microbes interact in the rhizosphere. The effect of drought stress on the exudation process and composition is rarely studied, especially in cereal crops. This study focuses on comparative metabolic profiling of the exudates from sensitive and tolerant genotypes of pearl millet after a period of drought stress. We employed a combined platform of gas and liquid chromatography coupled to mass spectrometry to cover both primary and secondary metabolites. The results obtained demonstrate that both genotype and drought stress have a significant impact on the concentration and composition of root exudates. The complexity and function of these differential root exudates are discussed. To reveal the potential effect of root exudates on the soil microbial community after a period of drought stress, we also tested for biological nitrification inhibition (BNI) activity. The analysis revealed a genotype-dependent enhancement of BNI activity after a defined period of drought stress. In parallel, we observed a genotype-specific relation of elongated root growth and root exudation under drought stress. These data suggest that the drought stress-dependent change in root exudation can manipulate the microbial soil communities to adapt and survive under harsh conditions. Supplementary Information: The online version contains supplementary material available at 10.1007/s00374-021-01578-w.

Identification of apple cultivars hypoallergenic for birch pollen-allergic individuals by a multidisciplinary in vitro and in vivo approach.

BACKGROUND: Birch pollen-related apple allergy is the most frequent IgE-mediated food allergy in Central-Northern Europe with Mal d 1 as major allergen. Its concentration in apples varies with the cultivar and storage time. Year-round appealing, hypoallergenic cultivars still are needed to satisfy the nutritional needs of affected individuals. We characterized three promising cultivars by multidisciplinary in vitro assays including long-term storage and by clinical challenges of allergic individuals before and after the birch pollen season. METHODS: Proteins were extracted from fruits of 'Santana', 'Golden Delicious' (GD), and three genuine cultivars in November 2018 and April 2019. Mal d 1-levels were analysed by mass spectrometry, SDS-PAGE, immunoblotting, competitive ELISA, and basophil activation tests. Twenty-eight allergic individuals underwent single-blinded open food challenges and skin testing with the cultivars and birch pollen in November 2018 and May 2019. Allergen-specific IgE-levels were determined. RESULTS: After storage all cultivars except 'Santana' were of appealing appearance and taste. Their Mal d 1 content had increased, also reflected by significantly amplified basophil activation and stronger reactions in clinical challenges. Besides, individuals showed boosted reactivity after pollen exposure indicated by enhanced allergen-specific IgE-levels and skin reactions to birch pollen. Still, all cultivars remained significantly less allergenic than GD and comparable to Santana in November 2018 in all assessments except for skin testing. CONCLUSIONS: Combined expertise in pomology and allergology identified promising new cultivars for allergic consumers. The evaluation of hypoallergenic apples should incorporate long-term storage and birch pollen exposure. Basophil activation tests may be suitable in the selection of promising cultivars for oral challenges.

Implant insertion using an orientation template and a full-guiding template - A prospective model analysis in a cohort of dentists participating in an implantology curriculum.

BACKGROUND: Dental implantology has become an established option for treating tooth loss over the recent decades. Before inserting an implant in a clinical situation, theoretical and practical training is recommended. Different methods are available to give assistance in determining the correctly planned implant position. In this study, two different guiding methods were assessed considering their accuracy for implant insertion in a group of dentists. METHODS: After three-dimensional planning of the implant positions, two surgical templates were manufactured as follows: in region 34 a stereolithographic template was used to perform a full-guided implant insertion, in region 44 a CAD/CAM milled template was used to determine the implant position and subsequently, perform a free-hand insertion. In total, 86 implants were placed in mandibular models by 43 dentists participating in a postgraduate curriculum. The differences between planned and achieved implant positions were measured and statistically analyzed. RESULTS: The implants inserted fully-guided showed a lower deviation of the three-dimensional angulation (2.266 ± 1.443 degrees vs. 7.954 ± 4.372 degrees) and the cumulated mismatch of the implant position (0.547 ± 0.237 mm vs. 1.160 ± 0.427 mm) compared to the free-handed mode. For the angulation and the mismatch at the implant base the differences were statistically significant (p < 0.001). CONCLUSIONS: Within the limits of the study it can be summarized that the full-guided implant insertion leads to a higher transfer accuracy compared to the free-hand method in a cohort of dentist inexperienced in dental implantology. However, the clinical effect has to be discussed as the study was performed using artificial mandibles and ideal conditions.

Dissecting Metabolism of Leaf Nodules in Ardisia crenata and Psychotria punctata.

Root-microbe interaction and its specialized root nodule structures and functions are well studied. In contrast, leaf nodules harboring microbial endophytes in special glandular leaf structures have only recently gained increased interest as plant-microbe phyllosphere interactions. Here, we applied a comprehensive metabolomics platform in combination with natural product isolation and characterization to dissect leaf and leaf nodule metabolism and functions in Ardisia crenata (Primulaceae) and Psychotria punctata (Rubiaceae). The results indicate that abiotic stress resilience plays an important part within the leaf nodule symbiosis of both species. Both species showed metabolic signatures of enhanced nitrogen assimilation/dissimilation pattern and increased polyamine levels in nodules compared to leaf lamina tissue potentially involved in senescence processes and photosynthesis. Multiple links to cytokinin and REDOX-active pathways were found. Our results further demonstrate that secondary metabolite production by endophytes is a key feature of this symbiotic system. Multiple anhydromuropeptides (AhMP) and their derivatives were identified as highly characteristic biomarkers for nodulation within both species. A novel epicatechin derivative was structurally elucidated with NMR and shown to be enriched within the leaf nodules of A. crenata. This enrichment within nodulated tissues was also observed for catechin and other flavonoids indicating that flavonoid metabolism may play an important role for leaf nodule symbiosis of A. crenata. In contrast, pavettamine was only detected in P. punctata and showed no nodule specific enrichment but a developmental effect. Further natural products were detected, including three putative unknown depsipeptide structures in A. crenata leaf nodules. The analysis presents a first metabolomics reference data set for the intimate interaction of microbes and plants in leaf nodules, reveals novel metabolic processes of plant-microbe interaction as well as the potential of natural product discovery in these systems.

Engineering and characterization of the long-acting glucagon-like peptide-1 analogue LY2189265, an Fc fusion protein.

BACKGROUND: Glucagon-like peptide-1 (GLP-1) receptor agonists are novel agents for type 2 diabetes treatment, offering glucose-dependent insulinotropic effects, reduced glucagonemia and a neutral bodyweight or weight-reducing profile. However, a short half-life (minutes), secondary to rapid inactivation by dipeptidyl peptidase-IV (DPP-IV) and excretion, limits the therapeutic potential of the native GLP-1 hormone. Recently, the GLP-1 receptor agonist exenatide injected subcutaneously twice daily established a novel therapy class. Developing long-acting and efficacious GLP-1 analogues represents a pivotal research goal. We developed a GLP-1 immunoglobulin G (IgG4) Fc fusion protein (LY2189265) with extended pharmacokinetics and activity. METHODS: In vitro and in vivo activity of LY2189265 was characterized in rodent and primate cell systems and animal models. RESULTS: LY2189265 retained full receptor activity in vitro and elicited insulinotropic activity in islets similar to native peptide. Half-life in rats and cynomolgus monkeys was 1.5-2 days, and serum immunoreactivity representing active compound persisted > 6 days. In rats, LY2189265 enhanced insulin responses during graded glucose infusion 24 h after one dose. LY2189265 increased glucose tolerance in diabetic mice after one dose and lowered weight and delayed hyperglycaemia when administered twice weekly for 4 weeks. In monkeys, LY2189265 significantly increased glucose-dependent insulin secretion for up to a week after one dose, retained efficacy when administered subchronically (once weekly for 4 weeks) and was well tolerated. CONCLUSIONS: LY2189265 retains the effects of GLP-1 with increased half-life and efficacy, supporting further evaluation as a once-weekly treatment of type 2 diabetes.

Accuracy of a Template-Guided Implant Surgery System with a CAD/CAM-Based Measurement Method: An In Vitro Study.

PURPOSE: The aim of this in vitro study was to evaluate the accuracy of template-guided implantation planned with implant-planning software (Implant Studio), comparing computer-aided design/computer-assisted manufacture (CAD/CAM)-based measurements with measurements via cone beam computed tomography (CBCT). MATERIALS AND METHODS: Thirty template-guided implantations were planned and performed on acrylic-resin models. The implant positions were detected with an intraoral scanner, evaluated with CAD quality-control software, and compared with the planned positions in the test group. Preliminary deviations were measured via CBCT in the control group of the first 10 samples and compared with the first 10 samples of the test group. RESULTS: When directly compared, measurements obtained using CBCT (control group) showed a trend toward greater deviations. In the CAD/CAM-based evaluation of the 30 samples, the mean ± SD deviation of the insertion axis from the planned implant axis was 2.011 ± 0.855 degrees. The mean deviations of the implant shoulders in the horizontal direction and at the implant apices were 0.725 ± 0.142 mm and 0.990 ± 0.244 mm, respectively. In the vertical direction, the mean deviation was 0.541 ± 0.129 mm. CONCLUSION: CAD/CAM-based measurements are more accurate than CBCT measurements. Therefore, this radiation-free measurement method is a viable diagnostic alternative. Implant planning with planning software and subsequent placement using surgical templates appears to be a reliable and precise therapeutic option in vitro. However, these findings will still have to be supported by in vivo studies.

Activation of liver X receptors and retinoid X receptors induces growth arrest and apoptosis in insulin-secreting cells.

Liver X receptors (LXRs) form functional heterodimers with the retinoid X receptors (RXRs) and regulate cholesterol, lipid, and glucose metabolism. We demonstrated previously that activation of LXR modulates insulin secretion in MIN6 cells and pancreatic islets. In this study we investigated the effects of the LXR agonist T0901317 and the RXR agonist 9-cis-retinoic acid (9cRA) on cell proliferation and apoptosis in MIN6 cells. Whereas T0901317 showed no effect on proliferation of MIN6 cells, combination of T0901317 with 9cRA inhibited cell proliferation. Flow cytometry analysis of cell cycle demonstrated that activation of LXR/RXR prevented MIN6 cells from G1 to G2 phase progression. Combination of T0901317 and 9cRA increased apoptosis rate and caspase-3/7 activity in MIN6 cells. Moreover, T0901317 or its combination with 9cRA significantly increased the cell susceptibility to free fatty acid- and cytokine-induced apoptosis. Treatment of MIN6 cells with LXR and RXR agonists produced a strong increase in expression of mothers against decapentaplegic homolog 3, a protein known to inhibit cell cycle G1/S phase progression and induce apoptosis. In isolated rat islets, the effect of palmitic acid on caspase-3/7 activity was increased with T0901317 alone and even more with the combination of T0901317 and 9cRA. Thus, activation of LXR/RXR signaling inhibits cell proliferation and induces apoptosis in pancreatic beta-cells.

Fibroblast growth factor-21 improves pancreatic beta-cell function and survival by activation of extracellular signal-regulated kinase 1/2 and Akt signaling pathways.

Fibroblast growth factor-21 (FGF-21) is a recently discovered metabolic regulator. Here, we investigated the effects of FGF-21 in the pancreatic beta-cell. In rat islets and INS-1E cells, FGF-21 activated extracellular signal-regulated kinase 1/2 and Akt signaling pathways. In islets isolated from healthy rats, FGF-21 increased insulin mRNA and protein levels but did not potentiate glucose-induced insulin secretion. Islets and INS-1E cells treated with FGF-21 were partially protected from glucolipotoxicity and cytokine-induced apoptosis. In islets isolated from diabetic rodents, FGF-21 treatment increased islet insulin content and glucose-induced insulin secretion. Short-term treatment of normal or db/db mice with FGF-21 lowered plasma levels of insulin and improved glucose clearance compared with vehicle after oral glucose tolerance testing. Constant infusion of FGF-21 for 8 weeks in db/db mice nearly normalized fed blood glucose levels and increased plasma insulin levels. Immunohistochemistry of pancreata from db/db mice showed a substantial increase in the intensity of insulin staining in islets from FGF-21-treated animals as well as a higher number of islets per pancreas section and of insulin-positive cells per islet compared with control. No effect of FGF-21 was observed on islet cell proliferation. In conclusion, preservation of beta-cell function and survival by FGF-21 may contribute to the beneficial effects of this protein on glucose homeostasis observed in diabetic animals.