Metformin severely impairs in vivo muscle oxidative capacity in a rat model of type 2 diabetes

Objective: To investigate the effects of metformin on in vivo and in vitro skeletal muscle mitochondrial function in Zucker diabetic fatty (ZDF) rats using 31P magnetic resonance spectroscopy (MRS) and high-resolution respirometry (HRR), respectively. Methods: 12-week old healthy (fa/+) and diabetic (fa/fa) ZDF rats were treated with metformin (0, 30, 100 or 300 mg/kg body weight/day) for 15 days by oral gavage. At day 14, in vivo31P MRS was performed on the tibialis anterior (TA) muscle to measure PCr recovery. At day 15, animals were killed and TA muscles were excised for in vitro HRR measurements. Results: Metformin treatment decreased PCr recovery rates in a dose-dependent manner in both healthy fa/+ and diabetic fa/fa rats. Whereas, the clinical dose of 30 mg/kg/day had no significant effect, PCr recovery rates were ~22% and ~47% decreased at 100 and 300 mg/kg/day. HRR measurements showed a similar, but less pronounced effect of metformin on in vitro mitochondrial function

Functional modes of proteins are among the most robust ones

It is shown that a small subset of modes which are likely to be involved in protein functional motions of large amplitude can be determined by retaining the most robust normal modes obtained using different protein models. This result should prove helpful in the context of several applications proposed recently, like for solving difficult molecular replacement problems or for fitting atomic structures into low-resolution electron density maps. Moreover, it may also pave the way for the development of methods allowing to predict such motions accurately.Comment: 4 pages, 5 figure

In vivo postprandial lipid partitioning in liver and muscle of diabetic rats is disturbed

Objective: To study in vivo lipid partitioning in insulin-resistant liver and muscle of diabetic rats using magnetic resonance spectroscopy (MRS). Methods: Four groups of n=6 male Zucker diabetic fatty rats were used for this study: obese, pre-diabetic fa/fa rats and lean, non-diabetic fa/+ littermates at the age of 6 weeks, and obese, diabetic fa/fa rats and lean, non-diabetic fa/+ littermates at the age of 12 weeks. 1H-[13C] MRS measurements were performed in liver and tibialis anterior muscle at baseline and 4, 24 and 48 h after oral administration of 1.5 g [U-13C] Algal lipid mixture per kg body weight. Results: At baseline, total lipid content was higher in fa/fa rats compared with fa/+ rats in both liver and muscle, and at both ages. Both in pre-diabetic and in diabetic fa/fa rats, hepatic lipid uptake was increased compared with non-diabetic fa/+ rats. Likewise, in muscle of diabetic fa/fa rats, lipid uptake was higher than in muscle of fa/+ rats. In contrast, lipid uptake in muscle of younger, pre-diabetic fa/fa rats was lower than in controls. Conclusion: In the pre-diabetic state, muscle appeared to be protected from massive lipid uptake, whereas lipid uptake in the liver was largely increased. In contrast, after developing full-blown diabetes, lipid uptake was highly elevated in both liver and muscle. This research was funded by a VIDI grant from the Netherlands Organisation for Scientific Research (NWO)

Can European banks' country-by-country reports reveal profit shifting? An analysis of the information content of EU banks' disclosures

We create a novel database of hand-collected information from the country-by-country reports (CbCRs) of more than 100 multinational bank groups headquartered in the EU for 2014-2016. We compare this new dataset with information from Orbis and Bank Focus to assess in how far the new disclosure obligation increased transparency on banks’ tax avoidance behavior. Our descriptive analysis shows that CbCRs uncover a large fraction of worldwide profits and real activities in terms of employees of EU bank groups, especially in tax havens. We also document a striking disconnect between reported profits and real activity, noting considerable heterogeneity between different tax havens and bank groups from different headquarter countries. Regression analysis based on CbCR data and Bank Focus data leads us to expect a tax semielasticity of banks’ reported profits of about -4.6. In this regard, CbCRs are indicative of a more pronounced tax sensitivity than conventional databases suggest. However, the lack of important economic variables (total assets and staff cost) impedes an exact estimation of banks’ profit shifting based on CbCR data alone and with standard methods. These insights are especially relevant in the context of the ongoing political discussions whether to introduce a public CbCR for all large multinational firms in the EU

Dual-isotope 111In/177Lu SPECT imaging as a tool in molecular imaging tracer design

The synthesis, design and subsequent pre-clinical testing of new molecular imaging tracers are topic of extensive research in healthcare. Quantitative dual-isotope SPECT imaging is proposed here as a tool in the design and validation of such tracers, as it can be used to quantify and compare the biodistribution of a specific ligand and its nonspecific control ligand, labeled with two different radionuclides, in the same animal. Since the biodistribution results are not blurred by experimental or physiological inter-animal variations, this approach allows determination of the ligand's net targeting effect. However, dual-isotope quantification is complicated by crosstalk between the two radionuclides used and the radionuclides should not influence the biodistribution of the tracer. Here, we developed a quantitative dual-isotope SPECT protocol using combined 111Indium and 177Lutetium and tested this tool for a well-known angiogenesis-specific ligand (cRGD peptide) in comparison to a potential nonspecific control (cRAD peptide). Dual-isotope SPECT imaging of the peptides showed a similar organ and tumor uptake to single-isotope studies (cRGDfK-DOTA, 1.5±0.8%ID cm -3; cRADfK-DOTA, 0.2±0.1%ID cm -3), but with higher statistical relevance (p-value 0.007, n=8). This demonstrated that, for the same relevance, seven animals were required in case of a single-isotope test design as compared with only three animals when a dual-isotope test was used. Interchanging radionuclides did not influence the biodistribution of the peptides. Dual-isotope SPECT after simultaneous injection of 111In and 177Lu-labeled cRGD and cRAD was shown to be a valuable method for paired testing of the in vivo target specificity of ligands in molecular imaging tracer design. © 2012 John Wiley & Sons, Ltd

Natural and chemotherapy-induced clonal evolution of tumors

Evolution and natural selection of tumoral clones in the process of transformation and the following carcinogenesis can be called natural clonal evolution. Its main driving factors are internal: genetic instability initiated by driver mutations and microenvironment, which enables selective pressure while forming the environment for cell transformation and their survival. We present our overview of contemporary research dealing with mechanisms of carcinogenesis in different localizations from precancerous pathologies to metastasis and relapse. It shows that natural clonal evolution establishes intratumoral heterogeneity and enables tumor progression. Tumors of monoclonal origin are of low-level intratumoral heterogeneity in the initial stages, and this increases with the size of the tumor. Tumors of polyclonal origin are of extremely high-level intratumoral heterogeneity in the initial stages and become more homogeneous when larger due to clonal expansion. In cases of chemotherapy-induced clonal evolution of a tumor, chemotherapy becomes the leading factor in treatment. The latest research shows that the impact of chemotherapy can radically increase the speed of clonal evolution and lead to new malignant and resistant clones that cause tumor metastasis. Another option of chemotherapy-induced clonal evolution is formation of a new dominant clone from a clone that was minor in the initial tumor and obtained free space due to elimination of sensitive clones by chemotherapy. As a result, in ~20% of cases, chemotherapy can stimulate metastasis and relapse of tumors due to clonal evolution. The conclusion of the overview formulates approaches to tumor treatment based on clonal evolution: in particular, precision therapy, prediction of metastasis stimulation in patients treated with chemotherapy, methods of genetic evaluation of chemotherapy efficiency and clonal-oriented treatment, and approaches to manipulating the clonal evolution of tumors are presented

In vivo magnetic resonance spectroscopy of lipid handling in steatotic rat liver

Objective: Examine lipid handling in liver of rats fed with different high-fat diets using 1H-[13C] magnetic resonance spectroscopy (MRS) together with oral administration of 13C labeled lipids. Methods: 6 male Wistar rats (11 weeks old; 348 ± 8g) were divided into three diet groups: low-fat (10% fat, CON), high-fat lard (45% fat, HFL), and high-fat palm oil (45%, HFP). After 10 weeks of diet, MRS experiments were performed at baseline, and 4 and 24 h after oral administration of 1.5 g [U-13C] Algal lipid mixture per kg body weight. Results: At 4 h after administration of the 13C labeled lipids, 13C enrichment of intracellular liver lipids was similarly increased in all three groups compared to baseline (CON: 0.031 ± 0.017 %; HFL: 0.045 ± 0.022 %; HFP: 0.033 ± 0.013 %), demonstrating that lipid uptake was not affected by the diet regimen. At 24 h, on the other hand, 13C enrichment of liver lipids decreased in CON, whereas in both high-fat diet groups the 13C enrichment did not change compared to 4 h, indicating a lower turnover of the stored liver lipids. Conclusion: High-fat diet feeding did not alter liver lipid uptake in rats, but resulted in a decreased turnover of the lipids stored in the liver. This research was funded by the Netherlands Consortium for Systems Biology (NCSB) which is part of the Netherlands Genomics Initiative/Netherlands Organisation for Scientific Research