Influence of different cutting instruments and rotational speeds on heat generation and cutting efficiency when sectioning different types of zirconia.

PURPOSE: The purpose of this study was to evaluate the temperature generated on the intaglio surface and efficiency when cutting different types of zirconia with different rotary instruments and rotational speeds. METHODS: A conventional diamond rotary instrument (Brasseler, grit size 107 µm) and special diamond rotary instrument marketed to cut zirconia (4 ZR, Brasseler, grit size 126 µm) were tested on 3Y-TZP and 4Y-TZP zirconia with a rotation speed of 100,000 rpm and 200,000 rpm. Zirconia specimens were cut under water cooling (110 mL/min) in a custom-made holder attached to a universal testing machine. The temperature was recorded with infrared sensors pointing at the intaglio surface of the zirconia specimens. RESULTS: A rotation speed of 200,000 rpm resulted in significantly shorter cutting times, but also in significantly higher temperatures at the intaglio surface of the zirconia specimens compared with a rotation speed of 100,000 rpm. Significantly shorter cutting times were observed for the conventional diamond rotary instrument than for the special rotary instrument marketed to cut zirconia. Using the special rotary instrument, significantly longer cutting times were recorded for 3Y-TZP than for 4Y-TZP. CONCLUSIONS: A conventional diamond rotary instrument was more efficient than a special rotary instrument. However, to avoid high temperatures when cutting zirconia clinically, a rotation speed of 100,000 rpm is recommended.

Influence of pretreating radicular dentin with different polyacrylic acids and isopropanol on the retention of posts.

STATEMENT OF PROBLEM: The optimal pretreatment of radicular dentin before cementing a post with glass ionomer cement is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the retention of prefabricated tapered titanium posts to endodontically treated teeth after applying different pretreatment protocols on the radicular dentin. MATERIAL AND METHODS: The coronal part of 32 single-rooted human teeth was removed 1-mm coronally to the cemento-enamel junction. All specimens received endodontic treatment, and the root canals were prepared with an instrument to a depth of 10 mm to receive a titanium post. The dentin walls of each specimen were roughened with a hand-held diamond cutting instrument. The specimens were randomly divided according to the surface treatments into 4 groups (n=8): KW: etched with 20% to 30% polyacrylic acid (PAA) (Ketac Conditioner) and rinsed with water; KWI: etched with 20% to 30% PAA, rinsed with water and 70% isopropanol; DW: etched with 30% to 50% PAA (Durelon Liquid) and rinsed with water; DWI: etched with 30% to 50% PAA, rinsed with water and 70% isopropanol. The prefabricated titanium posts were airborne-particle abraded and cemented with glass ionomer cement. The specimens were fixed in custom-made brass cylindrical holders with autopolymerizing acrylic resin with the holder parallel to the long axis of the post. All specimens were stored in water for 3 days at 37 °C. Retention was evaluated using a tensile test with a universal testing machine (Zwick Z010) at a crosshead speed of 2 mm/min. Data were statistically analyzed with a 1-way ANOVA, followed by the Tukey post hoc test for pairwise comparisons between groups (α=.05). RESULTS: Mean ±standard deviation retention values ranged from 201.8 ±55.5 N (KW) to 328.1 ±70.9 N (DWI). Groups DWI and KWI (316 ±58.3 N) showed statistically higher retention values than group KW (P<.05) but did not significantly differ from retention values obtained in group DW (P>.05). CONCLUSIONS: An additional final rinse with isopropanol after using PAA increased the retention of the post significantly for all groups. Although group DWI achieved the highest retention values, pretreatment of radicular dentin as in group KWI may also be considered.

Extrusion-based 3D printing of osteoinductive scaffolds with a spongiosa-inspired structure.

Critical-sized bone defects resulting from trauma, inflammation, and tumor resections are individual in their size and shape. Implants for the treatment of such defects have to consider biomechanical and biomedical factors, as well as the individual conditions within the implantation site. In this context, 3D printing technologies offer new possibilities to design and produce patient-specific implants reflecting the outer shape and internal structure of the replaced bone tissue. The selection or modification of materials used in 3D printing enables the adaption of the implant, by enhancing the osteoinductive or biomechanical properties. In this study, scaffolds with bone spongiosa-inspired structure for extrusion-based 3D printing were generated. The computer aided design process resulted in an up scaled and simplified version of the bone spongiosa. To enhance the osteoinductive properties of the 3D printed construct, polycaprolactone (PCL) was combined with 20% (wt) calcium phosphate nano powder (CaP). The implants were designed in form of a ring structure and revealed an irregular and interconnected porous structure with a calculated porosity of 35.2% and a compression strength within the range of the natural cancellous bone. The implants were assessed in terms of biocompatibility and osteoinductivity using the osteosarcoma cell line MG63 and patient-derived mesenchymal stem cells in selected experiments. Cell growth and differentiation over 14 days were monitored using confocal laser scanning microscopy, scanning electron microscopy, deoxyribonucleic acid (DNA) quantification, gene expression analysis, and quantitative assessment of calcification. MG63 cells and human mesenchymal stem cells (hMSC) adhered to the printed implants and revealed a typical elongated morphology as indicated by microscopy. Using DNA quantification, no differences for PCL or PCL-CaP in the initial adhesion of MG63 cells were observed, while the PCL-based scaffolds favored cell proliferation in the early phases of culture up to 7 days. In contrast, on PCL-CaP, cell proliferation for MG63 cells was not evident, while data from PCR and the levels of calcification, or alkaline phosphatase activity, indicated osteogenic differentiation within the PCL-CaP constructs over time. For hMSC, the highest levels in the total calcium content were observed for the PCL-CaP constructs, thus underlining the osteoinductive properties.

Activation of Endogenous H2S Biosynthesis or Supplementation with Exogenous H2S Enhances Adipose Tissue Adipogenesis and Preserves Adipocyte Physiology in Humans.

Aims: To investigate the impact of exogenous hydrogen sulfide (H2S) and its endogenous biosynthesis on human adipocytes and adipose tissue in the context of obesity and insulin resistance. Results: Experiments in human adipose tissue explants and in isolated preadipocytes demonstrated that exogenous H2S or the activation of endogenous H2S biosynthesis resulted in increased adipogenesis, insulin action, sirtuin deacetylase, and PPARγ transcriptional activity, whereas chemical inhibition and gene knockdown of each enzyme generating H2S (CTH, CBS, MPST) led to altered adipocyte differentiation, cellular senescence, and increased inflammation. In agreement with these experimental data, visceral and subcutaneous adipose tissue expression of H2S-synthesising enzymes was significantly reduced in morbidly obese subjects in association with attenuated adipogenesis and increased markers of adipose tissue inflammation and senescence. Interestingly, weight-loss interventions (including bariatric surgery or diet/exercise) improved the expression of H2S biosynthesis-related genes. In human preadipocytes, the expression of CTH, CBS, and MPST genes and H2S production were dramatically increased during adipocyte differentiation. More importantly, the adipocyte proteome exhibiting persulfidation was characterized, disclosing that different proteins involved in fatty acid and lipid metabolism, the citrate cycle, insulin signaling, several adipokines, and PPAR, experienced the most dramatic persulfidation (85-98%). Innovation: No previous studies investigated the impact of H2S on human adipose tissue. This study suggests that the potentiation of adipose tissue H2S biosynthesis is a possible therapeutic approach to improve adipose tissue dysfunction in patients with obesity and insulin resistance. Conclusion: Altogether, these data supported the relevance of H2S biosynthesis in the modulation of human adipocyte physiology. Antioxid. Redox Signal. 35, 319-340.

Secure and precise insertion of minimally invasive resin-bonded fixed dental prostheses after ridge augmentation by means of a positioning splint.

OBJECTIVE: Single-retainer resin-bonded fixed dental prostheses (RBFDPs) are described as an excellent minimally invasive treatment modality for the replacement of a single missing incisor even in cases of congenitally missing teeth that are often associated with hard and soft tissue defects that need to be properly managed to optimize the esthetic outcome. The lack of a retentive form due to the minimally invasive preparation form makes the adhesive bonding procedure for RBFDPs relatively technique-sensitive and might discourage practitioners from offering this treatment modality. CLINICAL CONSIDERATIONS: A patient with both maxillary lateral incisors congenitally missing was assessed for eligibility for treatment with RBFDPs. Bilateral horizontal ridge defects were present and treated through ridge augmentation to ensure an ovate pontic design and enhance the esthetic outcome. A minimally invasive preparation within enamel was conducted; the restorations were digitally designed and milled out of (3Y-TZP) zirconia ceramic with labial veneering with feldspathic ceramic for enhanced esthetics. An improved design of positioning splints was used for the adhesive bonding procedure to ensure exact, secure, and flawless insertion of the restorations. CONCLUSIONS: RBFDPs offer a highly esthetic treatment modality for missing teeth in the anterior area. Tissue defects could be overcome be means of a minor oral surgery, while using improved positioning splints might ensure flawless adhesive bonding and promote the usage of RBFDPs. CLINICAL SIGNIFICANCE: Hard and soft tissue defects can be remarkably optimized through a minor ridge augmentation. Improved positioning splints allow an easy and secure positioning as well as visual inspection of the seating in end-position and complete removal of resin cement excess. Implementing the concept of insertion splints might promote RBFDPs for anterior tooth replacement as it helps preventing bonding errors.

5-year randomized multicenter clinical trial on single dental implants placed in the midline of the edentulous mandible.

OBJECTIVES: This multicenter randomized controlled clinical trial was conducted to investigate whether the loading protocol of single dental implants placed in the midline of edentulous mandibles will influence the implant survival or prosthetic maintenance. MATERIALS AND METHODS: In total, 158 patients were randomly assigned either to the immediate loading group (n = 81) or to the delayed loading group (n = 77). All implants were loaded with an overdenture retained by a ball attachment. RESULTS: After 5 years, 102 patients attended the follow-up investigation. Immediately loaded single implants in the midline of the edentulous mandible revealed a statistically significant lower survival rate than implants loaded conventionally over an observation period of 5 years. In the immediate loading group, 9 implants failed within the first three months of implant loading. No further implant loss was recorded for this group. Two implants failed in the delayed loading group, whereas one implant had to be removed during second-stage surgery and the second five years after implant loading. Non-inferiority of the survival rate of the midline implant of the immediate loading group, compared with the delayed loading group, could not be shown (p = .79, CI immediate loading: 74.9%; 100.0%, CI delayed loading: 73.0%; 100.0%). The observed difference in implant survival between the two treatment groups over time was statistically significant. CONCLUSIONS: The results of the present study indicate that immediate loading of a single mandibular implant in the edentulous mandible should be considered only in exceptional cases.

COMP-Ang-1 Improves Glucose Uptake in db/db Mice with Type 2 Diabetes.

Cartilage oligomeric matrix protein (COMP)-Angiopoietin-1 is a potent angiopoietin-1 (Ang-1) variant that possesses therapeutic potential in angiogenesis and vascular endothelial dysfunction. Noteworthy, we have shown that COMP-Ang-1 improves hyperglycemia and neuroregeneration in ob/ob mice. However, the mechanism of the antidiabetic effect of COMP-Ang-1 is completely unknown. Therefore, we elucidated the diabetes protective molecular mechanisms of COMP-Ang-1 in diabetic db/db mouse model. COMP-Ang-1 (0.5 ng/g body weight) or aqueous NaCl solution was injected intraperitoneally per day in 21 consecutive days into 3-month old, male db/db mice (n=10 per group). Blood glucose and HbA1c levels were determined at baseline and 21 days after COMP-Ang-1 or NaCl treatment. The effect of COMP-Ang-1 on glucose uptake was investigated by euglycemic-hyperinsulinemic clamp studies and key genes of glucose metabolism were studied by Western blot analysis. Our findings indicate that COMP-Ang-1 improves glucose metabolism in a tissue specific manner by regulating HIF-1α transcriptional genes of GLUT-1 expression.

School-Class Co-Ethnic and Immigrant Density and Current Smoking among Immigrant Adolescents.

Although the school-class is known to be an important setting for adolescent risk behavior, little is known about how the ethnic composition of a school-class impacts substance use among pupils with a migration background. Moreover, the few existing studies do not distinguish between co-ethnic density (i.e., the share of immigrants belonging to one's own ethnic group) and immigrant density (the share of all immigrants). This is all the more surprising since a high co-ethnic density can be expected to protect against substance use by increasing levels of social support and decreasing acculturative stress, whereas a high immigrant density can be expected to do the opposite by facilitating inter-ethnic conflict and identity threat. This study analyses how co-ethnic density and immigrant density are correlated with smoking among pupils of Portuguese origin in Luxembourg. A multi-level analysis is used to analyze data from the Luxembourg Health Behavior in School-Aged Children study (N = 4268 pupils from 283 classes). High levels of co-ethnic density reduced current smoking. In contrast, high levels of immigrant density increased it. Thus, in research on the health of migrants, the distinction between co-ethnic density and immigrant density should be taken into account, as both may have opposite effects.

In vitro proinflammatory gene expression changes in human whole blood after contact with plasma-treated implant surfaces.

BACKGROUND: The aim of this in vitro study was to identify changes in gene expression of proinflammatory cytokines in human whole blood after contact with titanium implant surfaces after plasma treatment. MATERIALS AND METHODS: Grade 4 titanium dental implants were conditioned with low-pressure plasma (LPP) and atmospheric-pressure plasma (APP) and submerged in human whole blood in vitro. Unconditioned implants and blood samples without implants served as control and negative control groups, respectively. Sampling was performed at 1, 8, and 24 h. Changes in mRNA expression levels of interleukin 1-beta (IL1-ß) and tumor necrosis factor-alpha (TNF-α) were assessed using RT-qPCR. RESULTS: In the control group, significant increases in IL1-ß and TNF-α expression were observed. Significant decreases in the expression of IL1-ß and TNF-α were identified in blood with implants after plasma treatment. CONCLUSION: Differences in gene expression of proinflammatory cytokines after incubation of plasma-conditioned titanium implants can be assessed using human whole blood. The results of the present study indicate that plasma treatment (APP and LPP) of titanium dental implants leads to downregulation of proinflammatory cytokine gene expression, which might be beneficial in early osseointegration.

Tick-tock hedgehog-mutual crosstalk with liver circadian clock promotes liver steatosis.

BACKGROUND & AIMS: The mammalian circadian clock controls various aspects of liver metabolism and integrates nutritional signals. Recently, we described Hedgehog (Hh) signaling as a novel regulator of liver lipid metabolism. Herein, we investigated crosstalk between hepatic Hh signaling and circadian rhythm. METHODS: Diurnal rhythms of Hh signaling were investigated in liver and hepatocytes from mice with ablation of Smoothened (SAC-KO) and crossbreeds with PER2::LUC reporter mice. By using genome-wide screening, qPCR, immunostaining, ELISA and RNAi experiments in vitro we identified relevant transcriptional regulatory steps. Shotgun lipidomics and metabolic cages were used for analysis of metabolic alterations and behavior. RESULTS: Hh signaling showed diurnal oscillations in liver and hepatocytes in vitro. Correspondingly, the level of Indian Hh, oscillated in serum. Depletion of the clock gene Bmal1 in hepatocytes resulted in significant alterations in the expression of Hh genes. Conversely, SAC-KO mice showed altered expression of clock genes, confirmed by RNAi against Gli1 and Gli3. Genome-wide screening revealed that SAC-KO hepatocytes showed time-dependent alterations in various genes, particularly those associated with lipid metabolism. The clock/hedgehog module further plays a role in rhythmicity of steatosis, and in the response of the liver to a high-fat diet or to differently timed starvation. CONCLUSIONS: For the first time, Hh signaling in hepatocytes was found to be time-of-day dependent and to feed back on the circadian clock. Our findings suggest an integrative role of Hh signaling, mediated mainly by GLI factors, in maintaining homeostasis of hepatic lipid metabolism by balancing the circadian clock. LAY SUMMARY: The results of our investigation show for the first time that the Hh signaling in hepatocytes is time-of-day dependent, leading to differences not only in transcript levels but also in the amount of Hh ligands in peripheral blood. Conversely, Hh signaling is able to feed back to the circadian clock.

Changes in proinflammatory gene expression in human whole blood after contact with UV-conditioned implant surfaces.

OBJECTIVES: The aim of this in vitro study was to assess changes in the gene expression of proinflammatory cytokines in human whole blood after contact with titanium implant surfaces conditioned by UV light. To this end, expression levels of proinflammatory cytokines were analyzed in vitro in human whole blood. MATERIALS AND METHODS: Dental implants made of grade 4 titanium were conditioned by UV light in a UV device and submerged in human whole blood. Unconditioned implants served as controls, and blood samples without implants served as the negative control group. Sampling was performed at 1, 8, and 24 h. Changes in the expression levels of interleukin-1ß (IL1B) and tumor necrosis factor alpha (TNF) were assessed using RT-qPCR at the mRNA level. RESULTS: The gene expression of IL1B was significantly suppressed in the test group over the observation period compared to the control group during the 1-8 h after having contact between the implant surface and the blood. The gene expression of TNF was not significantly altered by UV conditioning after 1 and 8 h of observation, but both cytokine expression levels were increased significantly after 24 h. CONCLUSIONS: Differences in the gene expression of proinflammatory cytokines after insertion of UV-conditioned titanium implants can be assessed using a human whole blood test. UV-conditioned implant surfaces apparently suppress the release of IL1B in vitro. CLINICAL RELEVANCE: The results of our publication demonstrate that modulation of the early inflammatory response in human whole blood is possible by surface treatment with UV light. In particular, the suppression of IL1B expression, especially after the initial contact of blood cells, may be beneficial in the osseointegration of titanium implants by positively influence the balance between rejection and acceptance of an implant.

Effects of Weight Loss on Glutathione Peroxidase 3 Serum Concentrations and Adipose Tissue Expression in Human Obesity.

BACKGROUND/AIMS: Altered expression and circulating levels of glutathione peroxidase 3 (GPX3) have been observed in obesity and type 2 diabetes (T2D) across species. Here, we investigate whether GPX3 serum concentrations and adipose tissue (AT) GPX3 mRNA expression are related to obesity and weight loss. METHODS: GPX3 serum concentration was measured in 630 individuals, including a subgroup (n = 293) for which omental and subcutaneous (SC) GPX3 mRNA expression has been analyzed. GPX3 analyses include three interventions: 6 months after bariatric surgery (n = 80) or combined exercise/hypocaloric diet (n = 20) or two-step bariatric surgery (n = 24) studies. RESULTS: Bariatric surgery-induced weight loss (-25.8 ± 8.4%), but not a moderate weight reduction of -8.8 ± 6.5% was associated with significantly reduced GPX3 serum concentrations. GPX3 mRNA is significantly higher expressed in AT from individuals with normal glucose metabolism compared to T2D patients. SC AT GPX3 expression is significantly higher in lean compared to obese as well as in insulin-sensitive compared insulin-resistant individuals with obesity. Weight loss after bariatric surgery causes a significant increase in SC AT GPX3 expression. AT GPX3 expression significantly correlates with age, BMI, fat distribution, insulin sensitivity (only SC AT), but not with circulating GPX3. CONCLUSION: Our data support the notion that SC AT GPX3 expression is associated with obesity, fat distribution and related to whole body insulin resistance.

Effect of ultraviolet photofunctionalization of dental titanium implants on osseointegration.

OBJECTIVE: The aim of the current study was to evaluate the effect of ultraviolet (UV) photofunctionalization of dental titanium implants with exposure to the oral cavity on osseointegration in an animal model. METHODS: Forty-eight titanium implants (Camlog® Conelog® 4.3 mmx9.0 mm) were placed epicrestally into the edentulous jaws of three minipigs and implant stability was assessed by measuring the implant stability quotient (ISQ). Prior to implantation half of the implants were photofunctionalized with intense UV-light. After three months, the implants were exposed and ISQ was measured again. After six months of implant exposure, the minipigs were sacrificed and the harvested specimens were analyzed using histomorphometric, light, and fluorescence microscopy. MAIN RESULTS: Forty-two of 48 implants osseointegrated. The overall mean bone-implant contact area (BIC) was (64±22)%. No significant differences were found in BIC or ISQ value (multivariate analysis of variance (MANOVA), P>0.05) between implants with and without exposure to UV photofunctionalization. CONCLUSIONS: No significant effects were observed on osseointegration of dental titanium implants nine months after exposure of UV photofunctionalization.

p8 deficiency leads to elevated pancreatic beta cell mass but does not contribute to insulin resistance in mice fed with high-fat diet.

BACKGROUND: p8 was initially described as being overexpressed in acute pancreatitis and encoding a ubiquitous stress protein. Analysis of insulin sensitivity and glucose tolerance in p8-knockout and haplodeficient mice revealed counterintuitive results. Thus, we determined glycemic control of p8 in mice fed with standard (SD) and high-fat diet (HFD). METHODS: p8-/- and wild type (p8+/+) mice were used for analysis of glucagon (immunohistochemistry), insulin levels (ELISA) and beta cell mass. Hyperinsulinemic- euglycemic glucose clamp technique, i.p. glucose tolerance test (ipGTT), i.p. insulin tolerance test (ipITT) and metabolic chamber analysis were performed in SD (4% fat) and HFD (55% fat) groups. RESULTS: p8-/- mice showed no differences in glucagon or insulin content but higher insulin secretion from pancreatic islets upon glucose stimulation. p8 deficiency resulted in elevated beta cell mass but was not associated with increased insulin resistance in ipGTT or ipITT. Glucose clamp tests also revealed no evidence of association of p8 deficiency with insulin resistance. Metabolic chamber analysis showed equal energy expenditure in p8-/- mice and wild type animals. CONCLUSION: p8 depletion may contribute to glucose metabolism via stress-induced insulin production and elevated beta cell mass. Nevertheless, p8 knockout showed no impact on insulin resistance in SD and HFD-fed mice.

Single mandibular implant study (SMIS) - masticatory performance - results from a randomized clinical trial using two different loading protocols.

OBJECTIVES: This multi-centre randomized controlled trial was conducted to investigate, whether the masticatory performance of elderly edentulous patients is improved by placement of a single implant in the midline of the edentulous mandible, and whether improvements differ with respect to the loading protocol, i.e., implant is loaded either directly or three months later after second stage surgery. METHODS: Edentulous seniors aged 60-89 years were screened according to inclusion and exclusion criteria and 163 underwent implant placement. Of those, 158 were randomly assigned either to the direct loading group A (n=81) or the conventional loading group B (n=77). Chewing efficacy was obtained before treatment, one month after implant placement during the submerged healing phase (only group B) and 1 and 4 months after implant loading. RESULTS: The masticatory performance increased over time in both groups. Four months after loading, a significant increase was observed for both groups compared to the baseline data without implant (p≤0.05). However, between the two groups, chewing efficiency did not differ significantly at any point in time (p>0.05). CONCLUSIONS: A single midline implant in the edentulous mandible increases masticatory performance significantly, independently from the loading protocol. CLINICAL SIGNIFICANCE: A single midline implant in the edentulous mandible increases masticatory performance. The loading protocol has no influence.

Can one-wall bone defects be augmented with xenogenic bone grafting material alone?

OBJECTIVES: The main aim of this study was to evaluate the impact of xenogenic bovine bone grafting material particle size, addition of harvested autogenic bone as well as the influence of a periosteum on growth of newly formed bone, bone marrow, residual bone grafting material and connective tissue of one-wall defects. METHODS: Overall 32 augmentation sites were placed on the frontal skull of four minipigs and covered with titanium pin immobilized absorbable porcine membranes. After a 6 month healing period the harvested specimens were analyzed using light- and fluorescence microscopy. RESULTS: In the augmented areas 47%-57% bone, 14%-34% bone marrow, 10%-20% residual xenogenic bone grafting material and 4.5%-10% connective tissue were found. Admixture of autogenic bone resulted in statistically significantly more newly formed bone, more bone marrow, less residual xenogenic bone grafting material and less connective tissue (P ≤ 0.03). CONCLUSIONS: While augmenting one-wall defects seems to be possible with xenogenic grafting material and absorbable membranes alone, the addition of autogenic bone seems to benefit the augmentation site.

STK25 is a critical determinant in nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and 10-20% of patients with NAFLD progress to nonalcoholic steatohepatitis (NASH) with a high risk of cirrhosis, liver failure, and hepatocellular carcinoma. Despite its high medical importance, the molecular mechanisms controlling progression from simple liver steatosis to NASH remain elusive. We recently identified serine/threonine protein kinase (STK)25 as a critical regulator of ectopic lipid deposition, systemic glucose, and insulin homeostasis. To elucidate the role of STK25 in the development of NASH, we challenged Stk25-knockout and transgenic mice with a methionine and choline-deficient (MCD) diet. We show that Stk25-/- mice are protected against MCD-diet-induced NASH, as evidenced by repressed liver steatosis, oxidative damage, inflammation, and fibrosis, whereas Stk25 transgenic mice developed a more severe NASH phenotype, compared with corresponding wild-type littermates. Consistently, NASH features were suppressed in STK25-deficient human hepatocytes cultured in MCD medium, and reciprocally enhanced in STK25-overexpressing cells. We also found a significant positive correlation in human liver biopsies between STK25 expression and NASH development. The study provides evidence for multiple roles of STK25 in NASH pathogenesis and future investigations to address the potential therapeutic relevance of pharmacological STK25 inhibitors in prevention and treatment of NASH are warranted.-Amrutkar, M., Chursa, U., Kern, M., Nuñez-Durán, E., Ståhlman, M., Sütt, S., Borén, J., Johansson, B. R., Marschall, H.-U., Blüher, M., Mahlapuu, M. STK25 is a critical determinant in nonalcoholic steatohepatitis.

Protein kinase STK25 controls lipid partitioning in hepatocytes and correlates with liver fat content in humans.

AIMS/HYPOTHESIS: Type 2 diabetes is closely associated with pathological lipid accumulation in the liver, which is suggested to actively contribute to the development of insulin resistance. We recently identified serine/threonine protein kinase 25 (STK25) as a regulator of liver steatosis, whole-body glucose tolerance and insulin sensitivity in a mouse model system. The aim of this study was to assess the role of STK25 in the control of lipid metabolism in human liver. METHODS: Intracellular fat deposition, lipid metabolism and insulin sensitivity were studied in immortalised human hepatocytes (IHHs) and HepG2 hepatocellular carcinoma cells in which STK25 was overexpressed or knocked down by small interfering RNA. The association between STK25 mRNA expression in human liver biopsies and hepatic fat content was analysed. RESULTS: Overexpression of STK25 in IHH and HepG2 cells enhanced lipid deposition by suppressing ß-oxidation and triacylglycerol (TAG) secretion, while increasing lipid synthesis. Conversely, knockdown of STK25 attenuated lipid accumulation by stimulating ß-oxidation and TAG secretion, while inhibiting lipid synthesis. Furthermore, TAG hydrolase activity was repressed in hepatocytes overexpressing STK25 and reciprocally increased in cells with STK25 knockdown. Insulin sensitivity was reduced in STK25-overexpressing cells and enhanced in STK25-deficient hepatocytes. We also found a statistically significant positive correlation between STK25 mRNA expression in human liver biopsies and hepatic fat content. CONCLUSIONS/INTERPRETATION: Our data suggest that STK25 regulates lipid partitioning in human liver cells by controlling TAG synthesis as well as lipolytic activity and thereby NEFA release from lipid droplets for ß-oxidation and TAG secretion. Our findings highlight STK25 as a potential drug target for the prevention and treatment of type 2 diabetes.

Mechanical properties of collagen membranes: are they sufficient for orbital floor reconstructions?

INTRODUCTION: The most common reconstruction materials for orbital floor fractures are PDS (polydioxanone) foil and titanium meshes. These materials have advantages and disadvantages. Therefore, new materials are needed to improve surgical outcomes. MATERIALS AND METHODS: Three resorbable collagen membranes (Smartbrane(®), BioGide(®), Creos(®)) were tested for their mechanical properties (puncture strength) in mint and artificially aged (3, 6, 8 weeks) conditions and were compared to PDS foil, titanium meshes (0.25 mm, 0.5 mm) and human orbital floors (n = 7). RESULTS: The following puncture strengths were evaluated: human orbital floor, 0.81 ± 0.49 N/mm(2); 0.25 mm titanium mesh, 5.36 ± 0.25 N/mm(2); 0.5 mm titanium mesh, 16.08 ± 5.17 N/mm(2); Smartbrane, 0.74 ± 0.31 N/mm(2); BioGide, 1.65 ± 0.45 N/mm(2); and Creos, 2.81 ± 0.27 N/mm(2). After artificial aging, the puncture strengths were significantly reduced (p ≤ 0.05) at 3, 6 and 8 weeks as follows: Smartbrane, 0.05 ± 0.03 N/mm(2), 0.03 ± 0.02 N/mm(2), and 0.01 ± 0.01 N/mm(2), respectively; BioGide, 0.42 ± 0.06 N/mm(2), 0.41 ± 0.12 N/mm(2), and 0.32 ± 0.08 N/mm(2), respectively; and Creos, 2.02 ± 0.37 N/mm(2), 1.49 ± 0.42 N/mm(2), and 1.36 ± 0.42 N/mm(2), respectively. CONCLUSION: The tested materials showed sufficient puncture strength for orbital floor reconstruction in mint condition. Moreover, after artificial aging, the Creos and BioGide membranes showed sufficient resistance, while Smartbrane showed equivocal data after eight weeks. Therefore, collagen membranes have adequate properties for further in vivo investigations for orbital floor reconstructions.

The brown fat-enriched secreted factor Nrg4 preserves metabolic homeostasis through attenuation of hepatic lipogenesis.

Brown fat activates uncoupled respiration in response to cold temperature and contributes to systemic metabolic homeostasis. To date, the metabolic action of brown fat has been primarily attributed to its role in fuel oxidation and uncoupling protein 1 (UCP1)-mediated thermogenesis. Whether brown fat engages other tissues through secreted factors remains largely unexplored. Here we show that neuregulin 4 (Nrg4), a member of the epidermal growth factor (EGF) family of extracellular ligands, is highly expressed in adipose tissues, enriched in brown fat and markedly increased during brown adipocyte differentiation. Adipose tissue Nrg4 expression was reduced in rodent and human obesity. Gain- and loss-of-function studies in mice demonstrated that Nrg4 protects against diet-induced insulin resistance and hepatic steatosis through attenuating hepatic lipogenic signaling. Mechanistically, Nrg4 activates ErbB3 and ErbB4 signaling in hepatocytes and negatively regulates de novo lipogenesis mediated by LXR and SREBP1c in a cell-autonomous manner. These results establish Nrg4 as a brown fat-enriched endocrine factor with therapeutic potential for the treatment of obesity-associated disorders, including type 2 diabetes and nonalcoholic fatty liver disease (NAFLD).