Impact of Different Epoxidation Approaches of Tall Oil Fatty Acids on Rigid Polyurethane Foam Thermal Insulation

A second-generation bio-based feedstock—tall oil fatty acids—was epoxidised via two pathways. Oxirane rings were introduced into the fatty acid carbon backbone using a heterogeneous epoxidation catalyst-ion exchange resin Amberlite IR-120 H or enzyme catalyst Candida antarctica lipase B under the trade name Novozym^® 435. High functionality bio-polyols were synthesised from the obtained epoxidated tall oil fatty acids by oxirane ring-opening and subsequent esterification reactions with different polyfunctional alcohols: trimethylolpropane and triethanolamine. The synthesised epoxidised tall oil fatty acids (ETOFA) were studied by proton nuclear magnetic resonance. The chemical structure of obtained polyols was studied by Fourier-transform infrared spectroscopy and size exclusion chromatography. Average molecular weight and polydispersity of polyols were determined from size exclusion chromatography data. The obtained polyols were used to develop rigid polyurethane (PU) foam thermal insulation material with an approximate density of 40 kg/m³. Thermal conductivity, apparent density and compression strength of the rigid PU foams were determined. The rigid PU foams obtained from polyols synthesised using Novozym^® 435 catalyst had superior properties in comparison to rigid PU foams obtained from polyols synthesised using Amberlite IR-120 H. The developed rigid PU foams had an excellent thermal conductivity of 21.2–25.9 mW/(m·K).     

Troubleshooting digital macro photography for image acquisition and the analysis of biological samples

For years, image acquisition and analysis have been an important part of life science experiments to ensure the adequate and reliable presentation of research results. Since the development of digital photography and digital planimetric methods for image analysis approximately 20 years ago, new equipment and technologies have emerged, which have increased the quality of image acquisition and analysis. Different techniques are available to measure the size of stained tissue samples in experimental animal models of disease; however, the most accurate method is digital macro photography with software that is based on planimetric analysis. In this study, we described the methodology for the preparation of infarcted rat heart and brain tissue samples before image acquisition, digital macro photography techniques and planimetric image analysis. These methods are useful in the macro photography of biological samples and subsequent image analysis. In addition, the techniques that are described in this study include the automated analysis of digital photographs to minimize user input and exclude the risk of researcher-generated errors or bias during image analysis.     

Fasting-Mimicking Diet Reduces Trimethylamine N-Oxide Levels and Improves Serum Biochemical Parameters in Healthy Volunteers

Elevated plasma levels of trimethylamine N-oxide (TMAO) have been proposed as a diet-derived biomarker of cardiometabolic disease risk. Caloric restriction is the most common dietary intervention used to improve cardiometabolic health; however, novel trends suggest a fasting-mimicking diet (FMD) as a more feasible alternative. FMD is a variation of intermittent fasting, based on caloric restriction and limitation of protein sources of animal origin, applied in daily cycles during a 5-day period. As TMAO is intensively produced by gut microbiota after the consumption of animal-derived products, we aim to investigate whether a 5-day FMD affects plasma TMAO levels and markers of metabolic health. To investigate whether an increase in vegetable intake possesses similar effects on TMAO levels and metabolic parameters, healthy volunteers (n = 24) were subjected to a 5-day FMD and 19 volunteers served as a reference group (VEG). This group of volunteers consumed an additional four servings of vegetables per day, but otherwise stayed on their usual diet. FMD resulted in a twofold decrease in plasma TMAO levels, which was not evident in the volunteers from the VEG group. Moreover, FMD led to a weight loss of 2.8 ± 0.2 kg and a subsequent reduction in BMI compared to baseline. The FMD group exhibited a significant elevation in plasma ketone bodies (14-fold compared to baseline) and a decrease in IGF-1 levels by 37 ± 8 ng/mL. Since fasting glucose and C-peptide levels decreased, all volunteers in the FMD group showed improved insulin sensitivity and a decreased HOMA-IR index. In contrast, in the VEG group, only a slight reduction in plasma levels of fasting glucose and triglycerides was noted. In conclusion, we show that FMD is a viable strategy to reduce plasma levels of TMAO by limiting caloric intake and animal-derived protein consumption. The reduction in the level of TMAO could be an additional benefit of FMD, leading to a reduced risk of cardiometabolic diseases.     

Effect of inhibiting carnitine biosynthesis on male rat sexual performance

l-carnitine has a documented role as a cofactor in cellular energy metabolism and fatty acid β-oxidation pathways and it has also been considered to function in reproductive biology. We investigated whether decreasing concentrations of l-carnitine using an inhibitor of its biosynthesis, mildronate (3-(2,2,2-trimethylhydrazinium)-propionate), would influence the sexual behavior or sperm quality in male rats. Mildronate treatment induced a significant decrease in carnitine concentration and an increase in γ-butyrobetaine (GBB) concentration in both plasma and testes extracts. However, the expression of carnitine palmitoyltransferase I in testes and testosterone concentration in plasma was not changed in mildronate treated rat. Behavioral experiments demonstrated that mildronate treatment did not decrease the sexual motivation in both sexually naive and sexually experienced rats. The densities of spermatozoa in the cauda epididymis, as well as motility, were unchanged after mildronate treatment at a dose of 100 mg/kg. In conclusion, our study provides experimental evidence that mildronate induces decrease in the free carnitine concentration in rat testes, but does not decrease the sexual activity or sperm quality of male rats.     

Myocardial Infarct Size-Limiting and Anti-Arrhythmic Effects of Mildronate Orotate in the Rat Heart

Purpose  Mildronate and orotic acid act as modulators of energy metabolism and are considered as cardioprotective agents. This study was performed to compare the cardioprotective effects of mildronate, orotic acid and mildronate orotate. Methods  Male Wistar rats received mildronate, orotic acid or mildronate orotate for 14 days. The isolated rat heart infarction and isoproterenol-induced ischemia models were used to test the cardioprotective effects of compounds studied. Experimental arrhythmias were induced by the ligation of the left anterior descending coronary artery for 10 min with subsequent reperfusion or by administration of calcium chloride or aconitine at arrhythmogenic doses. Results  The data obtained showed a statistically significant decrease of necrotic area in 25% of infarcted rat hearts after 14 days of treatment with mildronate and orotic acid, whereas mildronate orotate decreased the infarct size by 50%. Moreover, we found that the administration of mildronate and its orotate salt decreased the duration and incidence of arrhythmias in experimental arrhythmia models. Conclusions  The study provides experimental evidence that the combination of orotic acid and mildronate possesses additive pharmacological effects and that mildronate orotate might be considered as a powerful therapeutic agent facilitating recovery from ischemia-reperfusion injury.     

Monophasic action potential mapping in swine and humans using modified-tip ablation catheter and electroanatomic mapping system

OBJECTIVE: To evaluate the feasibility of monophasic action potential (MAP) mapping using a modified-tip NaviStar catheter in swine and humans. METHODS: MAP mapping was performed using the modified-tip catheter at 71 +/- 21 atrial and 60 +/- 16 ventricular sites in 10 healthy pigs and at 56 ventricular sites in one patient, and using an ordinary Navi-Star catheter at 30 atrial sites in one patient and 50 +/- 14 ventricular sites in four patients. In an additional 20 patients, MAPs were also recorded at 9 +/- 2 atrial sites using the modified-tip catheter or at 12 +/- 9 atrial sites using the ordinary catheter. RESULTS: In pigs, the plateau amplitudes of the MAPs recorded using the modified-tip catheter were 4.1 +/- 3.2 mV for the atrial and 9.5 +/- 4.3 mV for the ventricular MAPs. In patients, both the ventricular and atrial MAPs recorded using the modified-tip catheter were significantly higher than using the ordinary catheters, 15.7 +/- 8 and 3.0 +/- 0.9 mV vs 9.5 +/- 3.9 and 2.0 +/- 0.6 mV for the ventricular and atrial MAPs, respectively (p < 0.0001). The baseline disturbances were <10% of the MAP amplitude in 95% of the pig and 96% of the patient MAPs. CONCLUSION: A modified-tip Navi-Star catheter could be used in swine and in humans for prompt recording of MAPs with acceptable amplitudes and baselines. MAP mapping using the modified-tip catheter is safe and feasible for clinical use.     

Mildronate treatment alters γ-butyrobetaine and l-carnitine concentrations in healthy volunteers

Objectives In this study, we aimed to investigate the effects of long‐term administration of the cardioprotective drug mildronate on the concentrations of l ‐carnitine and γ‐butyrobetaine in healthy volunteers. Methods Mildronate was administered perorally, at a dosage of 500 mg, twice daily. Plasma and urine samples were collected weekly. Daily meat consumption within an average, non‐vegetarian diet was monitored. l ‐Carnitine, γ‐butyrobetaine and mildronate concentrations were measured using the UPLC/MS/MS method. Key findings After 4 weeks, the average concentrations of l ‐carnitine in plasma significantly decreased by 18%. The plasma concentrations of γ‐butyrobetaine increased about two‐fold, and this effect was statistically significant in both the male and female groups. In urine samples, a significant increase in l ‐carnitine and γ‐butyrobetaine levels was observed, which provides evidence for increased excretion of both substances during the mildronate treatment. At the end of the treatment period, the plasma concentration of mildronate was 20 µm on average. There were no significant differences between the effects observed in female and male volunteers. Meat consumption partially reduced the l ‐carnitine‐lowering effects induced by mildronate. Conclusions Long‐term administration of mildronate significantly lowers l ‐carnitine plasma concentrations in non‐vegetarian, healthy volunteers.     

Determination of trace amounts of β tegafur in commercial α tegafur by powder X-ray diffractometric analysis

Objectives The main objective of this work was to develop a suitable analytical technique for determining trace amounts of the thermodynamically stable solid form in bulk samples of metastable form, to a sensitivity of 0.005%–1.0%. Tegafur (5‐fluoro‐1‐(tetrahydro‐2‐furyl)‐uracil) α and β crystalline forms were used as a model for this problem. Methods The trace content of the thermodynamically stable β polymorphic form in tegafur samples was increased by promoting phase transition from the bulk of thermodynamically metastable α form to β form, and achieving sufficient β form content for a quantitative powder X‐ray diffractometry (PXRD) analysis. The phase transition was stimulated by adding water to the samples and then grinding in controlled conditions (temperature, time, grinding speed). A calibration line was constructed using the least squares method. Key findings By using a solvent that does not form hydrates with the analysed polymorphs, it was possible to promote the phase transformation from metastable form to the thermodynamically stable form. After sample preparation, the thermodynamically stable solid form content in the analysed mixture had increased proportionally to the initial weight fraction (0.005%–1.0%) of the stable form seed crystals in the samples, and the coefficient of proportionality was 43.0 ± 0.9, with a standard deviation S_n = 1.5%. Conclusions A simple, sensitive, semi‐quantitative analytical method was developed for the low‐level determination of the thermodynamically stable polymorphic form in mixtures of thermodynamically stable and metastable polymorphs.     

Administration of L-carnitine and mildronate improves endothelial function and decreases mortality in hypertensive Dahl rats

Hypertension is a well established risk factor for the development of cardiovascular diseases and increased mortality. This study was performed to investigate the effects of the administration of L-carnitine or mildronate, an inhibitor of L-carnitine biosynthesis, or their combination on the development of hypertension-related complications in Dahl salt-sensitive (DS) rats fed with a high salt diet. Male DS rats were fed laboratory chow containing 8% NaCl from 7 weeks of age. Experimental animals were divided into five groups and treated for 8 weeks with vehicle (water; n = 10), L-carnitine (100 mg/kg, n = 10), mildronate (100 mg/kg, n = 10) or a combination of L-carnitine and mildronate at the doses above (n = 10). During the experiment, control group animals continued to consume a diet with normal salt content. Administration of the combination significantly improved the survival rate for 50% of the population. None of the tested compounds or their combination influenced high salt intake-induced hypertension, while treatment with mildronate and the combination for 8 weeks significantly decreased resting heart rate by 12% and 10%, respectively. Feeding with high salt diet had no influence on systolic function of the heart, but it induced thickening of the ventricular walls and development of heart hypertrophy that was not improved by the administration of tested compounds. In addition, administration of the combination attenuated the development of endothelial dysfunction in isolated aortic rings. In conclusion, our results demonstrate that treatment with a combination of L-carnitine and mildronate is protective against hypertension-induced complications in an experimental model of salt-induced hypertension.     

The cardioprotective effect of mildronate is diminished after co-treatment with L-carnitine

Mildronate, an inhibitor of L-carnitine biosynthesis and uptake, is a cardioprotective drug whose mechanism of action is thought to rely on the changes in concentration of L-carnitine in heart tissue. In the present study, we compared the cardioprotective effect of mildronate (100 mg/kg) and a combination of mildronate and L-carnitine (100 + 100 mg/kg) administered for 14 days with respect to the observed changes in l-carnitine level and carnitine palmitoyltransferase I (CPT-I)-dependent fatty acid metabolism in the heart tissues. Concentrations of L-carnitine and its precursor γ-butyrobetaine (GBB) were measured by ultraperformance liquid chromatography with tandem mass spectrometry. In addition, mitochondrial respiration, activity of CPT-I, and expression of CPT-IA/B messenger RNA (mRNA) were measured. Isolated rat hearts were subjected to ischemia-reperfusion injury. Administration of mildronate induced a 69% decrease in L-carnitine concentration and a 6-fold increase in GBB concentration in the heart tissue as well as a 27% decrease in CPT-I-dependent mitochondrial respiration on palmitoyl-coenzyme A. In addition, mildronate treatment induced a significant reduction in infarct size and also diminished the ischemia-induced respiration stimulation by exogenous cytochrome c. Treatment with a combination had no significant impact on L-carnitine concentration, CPT-I-dependent mitochondrial respiration, and infarct size. Our results demonstrated that the mildronate-induced decrease in L-carnitine concentration, concomitant decrease in fatty acid transport, and maintenance of the intactness of outer mitochondrial membrane in heart mitochondria are the key mechanisms of action for the anti-infarction activity of mildronate.