Revealing the quantum nature of the voltage-induced conductance changes in oxygen engineered yttrium oxide-based RRAM devices

In this work, the quasi-analog to discrete transition occurring in the current-voltage characteristic of oxygen engineered yttrium oxide-based resistive random-access memory (RRAM) devices is investigated in detail. In particular, the focus of our research is not on the absolute conductance values of this characteristic but on the magnitude of its conductance changes occurring during the reset process of the device. It is found that the detected changes correspond to conductance values predominantly of the order of the quantum unit of conductance G0 = 2e2/h, where e is the electron charge and h the Planck constant. This feature is observed even at conductance levels far above G0, i.e. where electron transport is seemingly diffusive. It is also observed that such behavior is reproducible across devices comprising yttrium oxide layers with different oxygen concentrations and measured under different voltage sweep rates. While the oxygen deficiency affects the total number of quantized conductance states, the magnitude of the changes in conductance, close to 1 G0, is invariant to the oxygen content of the functional layer.

2,5-[C4+C2] Ringtransformation of Pyrylium Salts with α-Sulfinylacetaldehydes

A rapid synthesis of chiral sulfoxide-functionalized meta-terphenyl derivatives by a 2,5-[C4+C2] ring transformation reaction of pyrylium salts with in situ generated enantiomerically pure α-sulfinylacetaldehydes is described in this paper. This synthetic method demonstrates, for the first time, the use of α-sulfinylacetaldehydes in a reaction sequence initiated by the nucleophilic attack of pyrylium salts by α-sulfinylcarbanions to generate chiral aromatic systems. The method presented shows a broad applicability starting with various methyl sulfoxides and a number of functionalized pyrylium salts, furnishing meta-terphenyls with complex substitution patterns from readily accessible starting compounds.

MXene Aerogel Derived Ultra-Active Vanadia Catalyst for Selective Conversion of Sustainable Alcohols to Base Chemicals

Selective oxidation reactions are an important class of the current chemical industry and will be highly important for future sustainable chemical production. Especially, the selective oxidation of primary alcohols is expected to be of high future interest, as alcohols can be obtained on technical scales from biomass fermentation. The oxidation of primary alcohols produces aldehydes, which are important intermediates. While selective methanol oxidation is industrially established, the commercial catalyst suffers from deactivation. Ethanol selective oxidation is not commercialized but would give access to sustainable acetaldehyde production when using renewable ethanol. In this work, it is shown that employing 2D MXenes as building blocks allows one to design a nanostructured oxide catalyst composed of mixed valence vanadium oxides, which outperforms on both reactions known materials by nearly an order of magnitude in activity, while showing high selectivity and stability. The study shows that the synthesis route employing 2D materials is key to obtain these attractive catalysts. V₄C₃T_x MXene structured as an aerogel precursor needs to be employed and mildly oxidized in an alcohol and oxygen atmosphere to result in the aspired nanostructured catalyst composed of mixed valence VO₂, V₆O₁₃, and V₃O₇. Very likely, the bulk stable reduced valence state of the material together coupled with the nanorod arrangement allows for unprecedented oxygen mobility as well as active sites and results in an ultra-active catalyst.

Effects of acute aerobic exercise on fatmetabolism in pre- and postmenopausal women of comparable body mass index

Problem: With menopause, the risk of cardiovascular diseases (CVD) increases significantly. A possible molecular mechanism is an estrogen-related change in fat metabolism. Endurance training has been demonstrated to reduce the risk of CVD and to have an impact on fat metabolism (FM). This study aims to analyze the ability of pre- (preW) and postmenopausal women (postW) of comparable body mass index (BMI) to activate their FM during endurance training. Methods: 12 preW and 12 postW were included. Serum Triglyceride, LDL, HbA1C, estradiol and body composition data were determined. The respiratory quotient (RQ) was determined during moderate 30-minute exercise (60% of the 4 mmol threshold) on an ergometer. Results: While the BMI of preW and postW was comparable, body fat (BF) (p=0.001), lean body mass (LBM) (p=0.001) and abdominal girth (AG) (p=0.003) were significantly different. Significant group effects could also be identified in HbA1c (p=0.001), cholesterol (p=0.001) and LDL (p=0.000) serum concentrations. RQ decreased during 30 minutes of cycling in preW and increased in postW (p=0.010) over time. Discussion: The higher AG and BF and the lower LBM demonstrates the change in body composition in postW. An accumulation of fat, especially in the trunk region, goes along with an increase of CVD in postW, even with a normal BMI. Conclusion: It is evident that postW show altered lipid metabolism compared to preW. Key Words: Menopause, Cardiovascular Risk Factor, Aerobic Training, Metabolism

Nanoscale Hybrid Amorphous/Graphitic Carbon as Key Towards Next-Generation Carbon-Based Oxidative Dehydrogenation Catalysts

A new strategy affords "non-nano" carbon materials as dehydrogenation catalysts that perform similarly to nanocarbons. Polymer-based carbon precursors that combine a soft-template approach with ion adsorption and catalytic graphitization are key to this synthesis strategy, thus offering control over macroscopic shape, texture, and crystallinity and resulting in a hybrid amorphous/graphitic carbon after pyrolysis. From this intermediate the active carbon catalyst is prepared by removing the amorphous parts of the hybrid carbon materials via selective oxidation. The oxidative dehydrogenation of ethanol was chosen as test reaction, which shows that fine-tuning the synthesis of the new carbon catalysts allows to obtain a catalytic material with an attractive high selectivity (82 %) similar to a carbon nanotube reference, while achieving 10 times higher space-time yields at 330 °C. This new class of carbon materials is accessible via a technically scalable, reproducible synthetic pathway and exhibits spherical particles with diameters around 100 μm, allowing unproblematic handling similar to classic non-nano catalysts.

Design and characterization of novel dirhodium coordination polymers – the impact of ligand size on selectivity in asymmetric cyclopropanation

Novel dirhodium coordination polymers are synthesized and characterized by various spectroscopic techniques. The catalysts exhibit good stability and excellent catalytic performance and selectivity in the cyclopropanation of diazooxindoles.

Parallel FTIR-ATR spectroscopy and gravimetry for the in situ hydrogen desorption measurement of NaAlH4 powder compacts

The measurement of the hydrogen desorption properties of sodium alanate (NaAlH₄) powder compacts presents a particular challenge due to various material changes. Therefore, a parallel measurement method for both spectral and gravimetrical data acquisition has been developed. The optical tracking of such chemical reactions with gaseous exhalation requires a special apparatus, since hydrogen absorption/desorption alters the granularity and volume of the sample. The technique combines a commercial Fourier transform infrared spectrometer with a self-developed heatable attenuated total reflection (ATR) cuvette that maintains the indispensable close contact between the ATR medium and sample. In particular, strongly absorbing or scattering samples can be characterized with respect to their transmission changes and their mass loss, due to the evanescent field's penetration depth of a few micrometers into the bulk of the sample. In this work, the first and second desorption step of 2 mol. % CeCl₃- and TiCl₃-doped NaAlH₄ compacts has been investigated. It was shown that the technique is able to monitor the hydrogen content in an alanate compact by means of the purely optically measured signal. In addition, a detailed analysis of the individual phase transformations was carried out. While the first reaction from the tetragonal to the monoclinic phase (NaAlH₄=>Na₃AlH₆) showed a conversion nearly linear in time, the following reaction from the monoclinic to the hydride phase (Na₃AlH₆=>NaH) showed a nonlinear desorption process. The phase changes were accompanied by discontinuous intensity changes of certain absorption bands, as well as by nonconstant changes over time. Therefore, the second-phase conversion could be divided into two regions with different desorption behaviors. The optical and gravimetric measurements were supported by x-ray diffraction measurements to verify the composition of the materials after hydrogen desorption. For the technical application of this method, e.g., for use as a level sensor, these special optical features are essential and must be taken into account.

Dirhodium Coordination Polymers for Asymmetric Cyclopropanation of Diazooxindoles with Olefins: Synthesis and Spectroscopic Analysis

A facile approach is reported for the preparation of dirhodium coordination polymers [Rh₂ (L1)₂ ]_n (Rh₂ -L1) and [Rh₂ (L2)₂ ]_n (Rh₂ -L2; L1=N,N'-(pyromellitoyl)-bis-L-phenylalanine diacid anion, L2=bis-N,N'-(L-phenylalanyl) naphthalene-1,4,5,8-tetracarboxylate diimide) from chiral dicarboxylic acids by ligand exchange. Multiple techniques including FTIR, XPS, and ¹ H→¹³ C CP MAS NMR spectroscopy reveal the formation of the coordination polymers. ¹⁹ F MAS NMR was utilized to investigate the remaining TFA groups in the obtained coordination polymers, and demonstrated near-quantitative ligand exchange. DR-UV-vis and XPS confirm the oxidation state of the Rh center and that the Rh-single bond in the dirhodium node is maintained in the synthesis of Rh₂ -L1 and Rh₂ -L2. Both coordination polymers exhibit excellent catalytic performance in the asymmetric cyclopropanation reaction between styrene and diazooxindole. The catalysts can be easily recycled and reused without significant reduction in their catalytic efficiency.

Direct Operando Spectroscopic Observation of Oxygen Vacancies in Working Ceria-Based Gas Sensors

Metal-oxide semiconductors are of great interest for gas-sensing applications. We provide new insights into the mode of operation of ceria-based gas sensors during ethanol gas sensing using combined operando Raman-gas-phase FTIR spectroscopy. Visible Raman spectroscopy is employed to monitor the presence of oxygen vacancies in ceria via F_2g mode softening, while simultaneously recorded FTIR spectra capture the gas-phase composition. Such an experimental approach allowing the direct observation of oxygen vacancies in metal-oxide gas sensors has not been reported in the literature. By systematically varying the gas atmosphere and temperature, we can relate the sensor response to the spectroscopic signals, enabling us to obtain new fundamental insight into the functioning of metal-oxide semiconductor gas sensors, as well as their differences from heterogeneous catalysts.

Comparison of Cyfra 21–1, Tpa and Tps in Lung Cancer, Urinary Bladder Cancer and Benign Diseases

Recently CYFRA 21–1, a new tumor marker measuring a fragment of cytokeratin 19, was introduced and proved to be suitable for therapy monitoring and follow-up of non-small cell lung carcinomas (NSCLC), in particular squamous cell carcinomas. Besides CYFRA 21–1 there are two other tumor markers, tissue polypeptide antigen (TPA) and tissue polypeptide-specific antigen (TPS), which also measure various cytokeratins in serum. In a retrospective study we investigated the clinical significance of these three cytokeratin markers in lung cancer and in carcinoma of the urinary bladder. For this purpose we investigated the sera of 50 healthy persons, 273 patients with various benign diseases, 218 patients with histologically proven lung cancer and 88 patients with carcinoma of the urinary bladder.

In a first step the specificity was established for the different reference groups and the cutoff values were fixed at a specificity of 95%. In lung cancer the single and combined sensitivities were calculated versus benign lung diseases (n = 58) as reference group. With single determinations CYFRA 21–1 proved to have the highest sensitivity in lung cancer in general (61%), in non-small cell lung carcinomas (64%), in squamous cell carcinomas (79%), in adenocarcinomas (54%) and in large cell carcinomas (65%). In small cell lung carcinomas (SCLC) NSE was confirmed to be the marker of choice (55%). With combined determinations a clear increase in sensitivity could only be reached in large cell carcinomas (CYFRA 21–1 + TPA: 77%) and in small cell carcinomas (CYFRA 21–1 + NSE: 62%). In cancer of the urinary bladder the sensitivities were established versus benign urological diseases (n = 73). CYFRA 21–1 showed with 38% true positive test results the highest sensitivity compared to TPA (27%) and TPS (23%).

From our investigations it was evident that TPA detects at least partially the same substance as CYFRA 21–1 (the sensitivities compared to the markers TPS, CEA, SCC and NSE were rather high, but not as high as for CYFRA 21–1) whereas TPS represents a completely different parameter of clinical chemistry (lowest number of true positive test results over the whole investigation), which apparently measures something completely different. These findings cleary correspond with the very recent results of immunoblotting comparing CYFRA 21–1, TPA and TPS.

Desmopressin testing in children with von Willebrand syndrome in haemostaseologic centers of Saxonia, Saxonia-Anhalt and Thuringia

The influence of desmopressin on hemostasis is mediated by the release of von Willebrand factor and of coagulation factor VIII from vascular endothelium. The necessity of testing desmopressin effectiveness on hemostasis is a matter of controversy and the performance of the test is not yet standardized. For this reason the desmopressin tests in 114 children with von Willebrand syndrome (type 1, n=98; type 2A, n=12; type 2M, n=2; type 2N, n=2) carried out in 7 paediatric haemostaseologic centers were retrospectively analyzed. The effectiveness of desmopressin was assessed using defined response criteria. As expected, the test performance showed a wide variation among the centers. In 99 children desmopressin was given intravenously as a short infusion at a dosage ranging from 0.25 to 0.41 μg/kg and in 15 intranasally at an absolute dose of 40 to 300 μg. The points of time for blood taking after desmopressin application ranged from 0.5 to 12 h. The absent desmopressin response in 7 patients (6%) and the partial response in 15 indicate the necessity of testing desmopressin effectiveness before the first therapeutic use. The application of desmopressin was well tolerated by the patients.

Novel dirhodium coordination polymers: the impact of side chains on cyclopropanation

Seven novel dirhodium coordination polymers (Rh₂–Ln) (n = 1–7) are prepared by employing bitopic ligands to connect dirhodium nodes.

RNase 7 downregulates TH2 cytokine production by activated human T cells

BACKGROUND

The antimicrobial peptide (AMP) RNase 7 is constitutively expressed in the epidermis of healthy human skin and has been found to be upregulated in chronic inflammatory skin diseases such as atopic dermatitis and psoriasis. Activated T cells in lesional skin of patients with atopic dermatitis (AD) and psoriasis (PSO) might be directly exposed to RNase 7. In addition to their antimicrobial activity, immunoregulatory functions have been published for several AMPs. In this study, we investigated immunoregulatory effects of the antimicrobial peptide RNase 7 on activated T cells.

METHODS

Isolated human CD3+T cells were stimulated with RNase 7 and screened for possible effects by mRNA microarray analysis. The results of the mRNA microarray were confirmed in isolated CD4+T cells and in polarized TH2 cells using skin-derived native RNase 7 and a recombinant ribonuclease-inactive RNase 7 mutant. Activation of GATA3 was analysed by electrophoretic mobility shift assay.

RESULTS

Treatment of activated human CD4+T cells and TH2 cells with RNase 7 selectively reduced the expression of TH2 cytokines (IL-13, IL-4 and IL-5). Experiments with a ribonuclease-inactive recombinant RNase 7 mutant showed that RNase 7 ribonuclease activity is dispensable for the observed regulatory effect. We further demonstrate that CD4+T cells from AD patients revealed a significantly less pronounced downregulation of IL-13 in response to RNase 7 compared to healthy control. Finally, we show that GATA3 activation was diminished upon cultivation of T cells with RNase 7.

CONCLUSION

Our data indicate that RNase 7 has immunomodulatory functions on TH2 cells and decreases the production of TH2 cytokines in the skin.

Interleukin-10 is downregulated in mononuclear cells from endotoxin tolerant humans

It has been shown that induction of endotoxin tolerance results in a decreased potential to produce pro-inflammatory cytokines such as TNF or IL-1. The present study was carried out to examine the capacity of peripheral blood mononuclear cells (PBMC) from endotoxin tolerant humans to synthesize the anti-inflammatory cytokines IL-10 and TGFβ in response to endotoxin. Four individuals were rendered endotoxin tolerant by daily i.v. injections of endotoxin. PBMC were isolated before tolerance induction and on day 4 after the last endotoxin treatment. The cells were stimulated with endotoxin ex vivo and cytokines in culture supernatants were determined. PBMC isolated on day 4 of all of the volunteers showed decreased TNFα, IL-6 and IL-10 synthesis upon endotoxin treatment in vitro compared to pretolerant cells, while no differences occurred with regard to the amount of TGFβ formed by PBMC before and after tolerance induction. Furthermore, no changes were found in the expression of HLA-DR on PBMC after tolerance induction.

Endotoxin-tolerant mice produce an inhibitor of tumor necrosis factor synthesis

The present study was carried out to investigate a new aspect of early endotoxin tolerance in mice. Evidence was obtained that early endotoxin tolerance is associated with the production of an activity interfering with the synthesis of tumor necrosis factor α (TNFα). LPS-tolerant mice, challenged with lipopolysaccharide (LPS) had lower serum levels of TNF than LPS-treated normal animals. In parallel, whole blood of tolerant mice, treated with LPS ex vivo generated lower levels of TNF than blood of normal animals. Plasma obtained 30 min after challenge with LPS from tolerant mice was inhibitory for TNF synthesis in whole blood of normal mice ex vivo. This seems to be specific for tolerant mice, since plasma prepared from normal, endotoxin-challenged mice was devoid of inhibitory activity for TNF production. The TNF-inhibitor in plasma of endotoxin tolerant mice did not interfere with the cytotoxic activity of murine recombinant TNFα on WEHI cells. Heat treatment of plasma destroyed the activity.

Dynamic behaviour of monohaptoallylpalladium species: internal coordination as a driving force in allylic alkylation chemistry

Contemporary catalytic procedures involving alkylpalladium(ii) have enriched the arsenal of synthetic organic chemistry. Those transformations usually rely on internal coordination through "directing groups", carefully designed to maximize catalytic efficiency and regioselectivity. Herein, we report structural and reactivity studies of a series of internally coordinated monohaptoallylpalladium complexes. These species enable the direct spectroscopic observation and theoretical study of π-σ-π interconversion processes. They further display unusual dynamic behavior which should be of direct relevance to chemistries beyond catalytic allylic alkylation.

Fish or n3-PUFA intake and body composition: a systematic review and meta-analysis

Obesity is a major public health issue and an important contributor to the global burden of chronic disease and disability. Studies indicate that fish and omega-3 polyunsaturated fatty acids (n3-PUFA) supplements may help prevent cardiovascular and metabolic diseases. However, the effect of fish oil on body composition is still uncertain, so we performed a systematic review of randomized controlled trials and the first meta-analysis on the association between fish or fish oil intake and body composition measures. We found evidence that participants taking fish or fish oil lost 0.59 kg more body weight than controls (95% confidence interval [CI]: -0.96 to -0.21). Treatment groups lost 0.24 kg m(-2) (body mass index) more than controls (-0.40 to -0.08), and 0.49 % more body fat than controls (-0.97 to -0.01). Fish or fish oil reduced waist circumference by 0.81 cm (-1.34 to -0.28) compared with control. There was no difference for fat mass and lean body mass. Further research is needed to confirm or refute our findings and to reveal possible mechanisms by which n3-PUFAs might reduce weight.

Crystal Structure of Bis(triethylammonium)closo-decahydrodecaborate, [(C2H5)3NH]2[B10H10]

The crystal structure of bis(triethylammonium)closo-decahydrodecaborate [bis(triethylammonium) decaboranate(10)], [(C2H5)3NH]2[B10H10], was determined and refined (space group Pmmn, no. 59, a = 989.7, b = 1333.7, c = 903.7 pm). The compound is a versatile starting material for many substances containing the [BioHio]2- entity and its derivatives. The closo-[B10H10]2- cluster is a bicapped square antiprism which is only slightly distorted. Its deviation from D4d symmetry is smaller than that of the B10 cages in every other compound containing this entity that have been structurally characterised. The presence of additional (N )H ---B3 interactions in form of multiple-centre bonds between the cations and the anions, which were postulated earlier and which should influence the cage symmetry, could not be confirmed. At 55 °C, the transition into a high temperature phase was investigated by X-ray powder diffraction. The high temperature phase crystallises in the tetragonal crystal system (a = 946.9, c = 1351.0 pm).

Analyzing Ammonia Bridges – and more about Bonding in Boron-rich Solids

Three types of boron-rich compounds in unusual bonding situations are described: First, salts that contain closo-hydroborate anions and exhibit hydrogen and dihydrogen bonds and a strong ammonia network; second, boron-rich metal borides with an unexpected metal–metal bond stabilized by Peierls distortion; and third, nanoscale metal borides that bind selectively to certain heptapeptides identified by the phage display technique.

Depression in early adulthood: prevalence and psychosocial correlates among young Swiss men

QUESTION UNDER STUDY

Depression in young adults is common, but data from Switzerland are scarce. Our study gives a point prevalence estimate of depression in young Swiss men, and describes the association between depression and education, material and social resources, and job/school satisfaction.

METHODS

We used data from the cross-sectional Swiss Federal Surveys of Adolescents (ch-x) from 2010 to 2011 comprising 9,066 males aged between 18 and 25 years. Depression was assessed by means of self-reports using the Patient Health Questionnaire (PHQ-9). Persons were categorised into three groups: depression, subthreshold depression, and no depression. We assessed the relationship between depression and education, material and social resources, and satisfaction with job/school. Differences according to depression status were tested with chi-square tests for categorical variables and one-way analyses of variance for continuous variables.

RESULTS

Point prevalence of depression (3.60%) and subthreshold depression (3.62%) was high. Poor mental health was associated with lower education in young adults (p <0.001), and with their parents' education (p = 0.024). Social resources in persons with depression and subthreshold depression were substantially reduced (i.e., social support and satisfaction with social relations; both p <0.001). Young men with depression and subthreshold depression also reported a current lack of satisfaction with job/school (p <0.001).

CONCLUSIONS

Prevalence of (subthreshold) depression is high in young Swiss men. Depression at this age might result in a bad long-term prognosis owing to its association with low satisfaction with job/school and low self-efficacy. Interventions should especially consider the lower social resources of young men with depression.

Selection of peptides binding to metallic borides by screening M13 phage display libraries

Background

Metal borides are a class of inorganic solids that is much less known and investigated than for example metal oxides or intermetallics. At the same time it is a highly versatile and interesting class of compounds in terms of physical and chemical properties, like semiconductivity, ferromagnetism, or catalytic activity. This makes these substances attractive for the generation of new materials. Very little is known about the interaction between organic materials and borides. To generate nanostructured and composite materials which consist of metal borides and organic modifiers it is necessary to develop new synthetic strategies. Phage peptide display libraries are commonly used to select peptides that bind specifically to metals, metal oxides, and semiconductors. Further, these binding peptides can serve as templates to control the nucleation and growth of inorganic nanoparticles. Additionally, the combination of two different binding motifs into a single bifunctional phage could be useful for the generation of new composite materials.

Results

In this study, we have identified a unique set of sequences that bind to amorphous and crystalline nickel boride (Ni₃B) nanoparticles, from a random peptide library using the phage display technique. Using this technique, strong binders were identified that are selective for nickel boride. Sequence analysis of the peptides revealed that the sequences exhibit similar, yet subtle different patterns of amino acid usage. Although a predominant binding motif was not observed, certain charged amino acids emerged as essential in specific binding to both substrates. The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni₃B emerged as the best binder for both substrates. Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni₃B nanoparticles.

Conclusions

This study is, to our knowledge, the first to identify peptides that bind specifically to amorphous and to crystalline Ni₃B nanoparticles. We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

Clock gene expression in the liver of streptozotocin-induced and spontaneous type 1 diabetic rats

Several investigations have shown a relation between diabetes and alterations of the liver circadian clock. We investigated the diurnal expression of clock genes and clock-controlled genes (CCGs) in 3-hour intervals for a 24-h period in the livers of male streptozotocin (STZ)-treated rats, male spontaneous type 1 diabetic LEW.1AR1-iddm (Iddm) rats, and Iddm rats treated for 10 days with insulin. Hepatic mRNA was extracted, and the relative expression of clock genes (Per1, Per2, Bmal1, Clock, Cry1), as well as CCGs (Dbp, E4bp4, RevErbα, Rorα, Pparγ), was analyzed by reverse transcription followed by real-time polymerase chain reaction. Diabetic STZ and Iddm rats, as well as insulin-substituted Iddm rats, exhibited a significant diurnal expression pattern of clock genes as determined by Cosinor analysis; however, the MESOR (midline estimating statistic of rhythm) of Bmal1, Per2, and Clock transcript expression was altered in Iddm and insulin-substituted Iddm rats. The hepatic expression of the CCGs Dbp and RevErbα revealed a diurnal rhythm in all investigated groups. Insulin administration to Iddm rats normalized the enhanced MESOR in the expression of Dbp, RevErbα, and E4bp4 to the levels of normoglycemic controls. Cosinor analysis indicated no diurnal rhythm of Pparγ expression in the livers of diabetic STZ or Iddm rats or in those of insulin-substituted Iddm rats. Also, insulin substitution could not reverse the decreased MESOR of Pparγ expression in Iddm rats. In consequence of the diabetic disease, changes in the expression of clock genes and CCGs suggest alterations in the hepatic peripheral clock mechanism.

GLUT4 in the endocrine pancreas--indicating an impact in pancreatic islet cell physiology?

The glucose transporter GLUT4 is well known to facilitate the transport of blood glucose into insulin-sensitive muscle and adipose tissue. In this study, molecular, immunohistochemical, and Western blot investigations revealed evidence that GLUT4 is also located in the mouse, rat, and human endocrine pancreas. In addition, high glucose decreased and insulin elevated the GLUT4 expression in pancreatic α-cells. In contrast, high glucose increased GLUT4 expression, whereas insulin led to a reduced expression level of the glucose transporter in pancreatic β-cells. In vivo experiments showed that in pancreatic tissue of type 2 diabetic rats as well as type 2 diabetic patients, the GLUT4 expression is significantly increased compared to the nondiabetic control group. Furthermore, type 1 diabetic rats exhibited reduced GLUT4 transcript levels in pancreatic tissue, whereas insulin treatment of type 1 diabetic animals enhanced the GLUT4 expression back to control levels. These data provide evidence for the existence of GLUT4 in the endocrine pancreas and indicate a physiological relevance of this glucose transporter as well as characteristic changes in diabetic disease.

Catecholamines are the key for explaining the biological relevance of insulin-melatonin antagonisms in type 1 and type 2 diabetes

In this paper, we analyze the biological relevance of melatonin in diabetogenesis. As has recently been demonstrated, melatonin decreases insulin secretion via specific melatonin receptor isoforms (MT1 and MT2) in the pancreatic β-cells. In addition, type 2 diabetic rats, as well as patients, exhibit decreased melatonin levels, whereas the levels in type 1 diabetic rats are increased. The latter effects were normalized by insulin substitution, which signifies that a specific receptor-mediated insulin-melatonin antagonism exists. These results are in agreement with several recent genome-wide association studies, which have identified a number of single nucleotide polymorphisms in the MTNR1B gene, encoding the MT2 receptor, that were closely associated with a higher prognostic risk of developing type 2 diabetes. We hypothesize that catecholamines, which decrease insulin levels and stimulate melatonin synthesis, control insulin-melatonin interactions. The present results support this assertion as we show that catecholamines are increased in type 1 but are diminished in type 2 diabetes. Another important line of inquiry involves the fact that melatonin protects the β-cells against functional overcharge and, consequently, hinders the development of type 2 diabetes. In this context, it is striking that at advanced ages, melatonin levels are reduced and the incidence of type 2 diabetes is increased. Thus, melatonin appears to have a protective biological role. Here, we strongly repudiate misconceptions, resulting from observations that melatonin reduces the plasma insulin level, that the blockage of melatonin receptors would be of benefit in the treatment of type 2 diabetes.

The insulin-melatonin antagonism: studies in the LEW.1AR1-iddm rat (an animal model of human type 1 diabetes mellitus)

AIMS/HYPOTHESIS

It is well documented that melatonin influences insulin secretion mediated by G-protein-coupled melatonin receptor isoforms MT1 and MT2, which are present in rat and human pancreatic islets, as well as in rat insulinoma cells. Recent investigations have proven that hyperinsulinaemic Goto-Kakizaki (GK) rats, which are a rat model of type 2 diabetic rats, and humans have decreased melatonin plasma levels, whereas a streptozotocin-induced rat model of diabetes developed reduced insulin levels combined with increased melatonin levels.

METHODS

Plasma levels of glucose, insulin and melatonin as well as RNA expression of pineal Aanat, Hiomt (also known as Asmt), insulin receptor, adrenoceptor β1 and the clock genes Per1 and Bmal1 (also known as Arntl) were determined in male and female LEW.1AR1-iddm rats as well as in insulin-substituted LEW.1AR1-iddm rats.

RESULTS

Severe hypoinsulinaemia in diabetic LEW.1AR1-iddm rats was associated with decreased body weight and increased melatonin plasma levels combined with mainly elevated expression of Aanat, Hiomt, pineal insulin receptor and adrenoceptor β1. The changes were normalised by insulin substitution. Diurnal profiles of plasma melatonin and of antagonistic clock genes Per1 and Bmal1 were maintained in diabetic and insulin-substituted rats.

CONCLUSIONS/INTERPRETATION

The assumed causal relation between elevated melatonin and reduced insulin levels in LEW.1AR1-iddm rats is supported by the observation that insulin substitution normalised these changes. Further support for this interpretation comes from the observation that in GK rats an increase of plasma insulin was combined with a decrease of plasma noradrenaline (norepinephrine), the most important activator of melatonin synthesis. These relationships between the noradrenergic and insulin pathway support the existence of melatonin-insulin antagonism.

Unmasking of a Recessive SCARF2 Mutation by a 22q11.12 de novo Deletion in a Patient with Van den Ende-Gupta Syndrome

Van den Ende-Gupta syndrome (VDEGS) is a congenital condition characterized by craniofacial and skeletal manifestations, specifically blepharophimosis, malar and maxillary hypoplasia, distinctive nose, arachnocamptodactyly, and long slender bones of the hands and feet. To date, only 24 patients have been described. It is generally thought that the syndrome is transmitted by an autosomal recessive mode of inheritance, although evidence for genetic heterogeneity has recently been presented. We report on a girl followed from birth up to 3 years of life with a set of peculiar minor anomalies, arachnocamptodactyly of hands and feet, characteristic of VDEGS in association with a 22q11.12 deletion. Recently, the VDEGS gene was mapped to the DiGeorge syndrome region on 22q11.2, and homozygous mutations in the SCARF2 gene were identified. We now report the first patient with VDEGS due to compound heterozygosity for the common 22q11.2 microdeletion and a hemizygous SCARF2 splice site mutation.