Memantine Prevents Cardiomyocytes Nuclear Size Reduction in the Left Ventricle of Rats Exposed to Cold Stress

OBJECTIVES: Memantine is an N-methyl-d-aspartate (NMDA) glutamate receptor antagonist used to treat Alzheimer's disease. Previous studies have suggested that receptor blockers act as neuroprotective agents; however, no study has specifically investigated the impact that these drugs have on the heart. We sought to evaluate the effects of memantine on nuclear size reduction in cardiac cells exposed to cold stress. METHOD: We used male EPM-Wistar rats (n=40) divided into 4 groups: 1) Matched control (CON); 2) Memantine-treated rats (MEM); 3) Rats undergoing induced hypothermia (IH) and 4) Rats undergoing induced hypothermia that were also treated with memantine (IHM). Animals in the MEM and IHM groups were treated by oral gavage administration of 20 mg/kg/day memantine over an eight-day period. Animals in the IH and IHM groups were submitted to 4 hours of hypothermia in a controlled environment with a temperature of - 8ºC on the last day of the study. RESULTS: The MEM group had the largest cardiomyocyte nuclear size (151 ± 3.5 &#956;m³ vs. CON: 142 ± 2.3 &#956;m³; p<0.05), while the IH group had the smallest mean value of nuclear size. The nuclear size of the IHM group was preserved (125 ± 2.9 &#956;m³) compared to the IH group (108 ± 1.7 &#956;m³; p<0.05). CONCLUSION: Memantine prevented the nuclear size reduction of cardiomyocytes in rats exposed to cold stress

Production of esters by biocatalysed transesterification in supercritical CO2 and Hexane

The development of sustainable processes that use renewable raw materials and minimize chemical and energetic waste has attracted considerable attention and represents a great challenge to both academic researchers and industrial experts. The use of enzymes to catalyse chemical transformations can constitute a more sustainable alternative to some traditional chemical processes and more than 100 biotransformations are already operated at an industrial scale [1]. Lipases usually operate in mild conditions and can catalyse both hydrolytic and synthetic reactions, depending on the surrounding medium. The hydrolysis of esters can be performed in water, but the reverse production reactions are not favoured in this medium, and are usually performed in organic solvents. Supercritical CO2 can constitute a more sustainable alternative to organic solvents as a reaction medium, provided that it does not have a direct adverse effect on the enzyme's active site or significantly reduce its activity. Decyl acetate was chosen as a model compound and its production by a transesterification reaction catalysed by Novozym 435 (immobilized Candida Antarctica Lipase B) was studied in both hexane and supercritical CO2. A comparative analysis between these two alternatives was performed, focusing on the differences on the enzyme's catalytic activity, solubilities of the substrates and mass transfer rates; which significantly affect the outcome of the reaction process and its productivity and provide information on when such solvents can be used. [1] Straathof, A.J.J., Panke, S., Schmid, A. The production of fine chemicals by biotransformations. Current Opinion in Biotechnology, 2002, 13(6), 548-556

Pressure and chemical substitution effects in the local atomic structure of BaFe2As2

The effects of K and Co substitutions and quasi-hydrostatic applied pressure (P<9 GPa) in the local atomic structure of BaFe2As2, Ba(Fe{0.937}Co{0.063})2As2 and Ba{0.85}K{0.15}Fe2As2 superconductors were investigated by extended x-ray absorption fine structure (EXAFS) measurements in the As K absorption edge. The As-Fe bond length is found to be slightly reduced (<~ 0.01 Angstroms) by both Co and K substitutions, without any observable increment in the corresponding Debye Waller factor. Also, this bond is shown to be compressible (k = 3.3(3)x10^{-3} GPa^{-1}). The observed contractions of As-Fe bond under pressure and chemical substitutions are likely related with a reduction of the local Fe magnetic moments, and should be an important tuning parameter in the phase diagrams of the Fe-based superconductors.Comment: 7 pages, 6 figure

Myocardium tissue changes caused by electrical transthoracic discharges in rats

<p>Abstract</p> <p>Background</p> <p>Cardiomyocytes cytoarchitecture changes caused by transthoracic countershocks have been focused recently. We aimed to evaluate the effects of electrical discharge application in the mitochondria structure in atrial myocardium of rats.</p> <p>Methods</p> <p>An electrical cardioverter was adapted to small rodent animals for our research. Electrical discharges were applied to the precordial region of 30 albino rats: (1) control group - animals that remained on resting period and were afterwards sacrificed; (2) electrical discharge group - animals that remained on resting period, followed by ten electrical discharges of 300 mV and sacrificed, and; (3) electrical post-discharge group - animals that remained on a resting period and received ten electrical discharges like the electrical discharge group, but were sacrificed seven days subsequently. We examined liver, adrenal and left atrium tissue fragments of the three groups.</p> <p>Results</p> <p>It was observed in control and post-discharge groups a normal cellular structure aspect with preserved architecture of cardiomyocytes and continuous sarcoplasmic membrane integrity. On the other hand, cardiac muscle fibers with mitochondrial edema and lysis occurred in the discharge group. Glycogen and adrenal lipids were not depleted in all groups.</p> <p>Conclusion</p> <p>These data suggest that transthoracic electrical discharges induce mitochondrial injuries in atrial cardiac cells of rats.</p

The effects of auditory stimulation with music on heart rate variability in healthy women

OBJECTIVES: There are no data in the literature with regard to the acute effects of different styles of music on the geometric indices of heart rate variability. In this study, we evaluated the acute effects of relaxant baroque and excitatory heavy metal music on the geometric indices of heart rate variability in women. METHODS: We conducted this study in 21 healthy women ranging in age from 18 to 35 years. We excluded persons with previous experience with musical instruments and persons who had an affinity for the song styles. We evaluated two groups: Group 1 (n = 21), who were exposed to relaxant classical baroque musical and excitatory heavy metal auditory stimulation; and Group 2 (n = 19), who were exposed to both styles of music and white noise auditory stimulation. Using earphones, the volunteers were exposed to baroque or heavy metal music for five minutes. After the first music exposure to baroque or heavy metal music, they remained at rest for five minutes; subsequently, they were re-exposed to the opposite music (70-80 dB). A different group of women were exposed to the same music styles plus white noise auditory stimulation (90 dB). The sequence of the songs was randomized for each individual. We analyzed the following indices: triangular index, triangular interpolation of RR intervals and Poincaré plot (standard deviation of instantaneous beat-by-beat variability, standard deviation of the long-term RR interval, standard deviation of instantaneous beat-by-beat variability and standard deviation of the long-term RR interval ratio), low frequency, high frequency, low frequency/high frequency ratio, standard deviation of all the normal RR intervals, root-mean square of differences between the adjacent normal RR intervals and the percentage of adjacent RR intervals with a difference of duration greater than 50 ms. Heart rate variability was recorded at rest for 10 minutes. RESULTS: The triangular index and the standard deviation of the long-term RR interval indices were reduced during exposure to both music styles in the first group and tended to decrease in the second group whereas the white noise exposure decreased the high frequency index. We observed no changes regarding the triangular interpolation of RR intervals, standard deviation of instantaneous beat-by-beat variability and standard deviation of instantaneous beat-by-beat variability/standard deviation in the long-term RR interval ratio. CONCLUSION: We suggest that relaxant baroque and excitatory heavy metal music slightly decrease global heart rate variability because of the equivalent sound level

Co-substitution effects on the Fe-valence in the BaFe2As2 superconducting compound: A study of hard x-ray absorption spectroscopy

The Fe K X-ray absorption near edge structure (XANES) of BaFe2-xCoxAs2 superconductors was investigated. No appreciable alteration in shape or energy position of this edge was observed with Co substitution. This result provides experimental support to previous ab initio calculations in which the extra Co electron is concentrated at the substitute site and do not change the electronic occupation of the Fe ions. Superconductivity may emerge due to bonding modifications induced by the substitute atom that weakens the spin-density-wave ground state by reducing the Fe local moments and/or increasing the elastic energy penalty of the accompanying orthorhombic distortion.Comment: 4+ pages, 4 figures. Published in Phys. Rev. Let

Guidance on the assessment of biocompatibility of biomaterials: Fundamentals and testing considerations.

BACKGROUND Assessing the biocompatibility of materials is crucial for ensuring the safety and well-being of patients by preventing undesirable, toxic, immune, or allergic reactions, and ensuring that materials remain functional over time without triggering adverse reactions. To ensure a comprehensive assessment, planning tests that carefully consider the intended application and potential exposure scenarios for selecting relevant assays, cell types, and testing parameters is essential. Moreover, characterizing the composition and properties of biomaterials allows for a more accurate understanding of test outcomes and the identification of factors contributing to cytotoxicity. Precise reporting of methodology and results facilitates research reproducibility and understanding of the findings by the scientific community, regulatory agencies, healthcare providers, and the general public. AIMS This article aims to provide an overview of the key concepts associated with evaluating the biocompatibility of biomaterials while also offering practical guidance on cellular principles, testing methodologies, and biological assays that can support in the planning, execution, and reporting of biocompatibility testing