Culture medium-dependent isoproterenol stability and its impact on DNA strand breaks formation and repair

Senescence-like Phenotype After Chronic Exposure to Isoproterenol in Primary Quiescent Immune Cells

Chronic stress is associated with a higher risk for carcinogenesis as well as age-related diseases and immune dysfunction. There is evidence showing that psychological stress can contribute to premature immunosenescence. Therefore, the question arose whether chronic exposure to catecholamine could drive immune cells into senescence. Peripheral blood mononuclear cells were isolated from whole blood. After repeated ex vivo treatment with isoproterenol, an epinephrine analog, well-established senescence biomarkers were assessed. We found (i) DNA double-strand break induction, (ii) telomere shortening, (iii) failure to proliferate, (iv) higher senescence-associated β-galactosidase activity, (v) decreases in caspases 3 and 7 activity, and (vi) strong upregulation of the proteoglycan versican accompanied by increased cellular adhesion suggesting the induction of a senescence-like phenotype. These results emphasize the complexity of the effect of isoproterenol on multiple cellular processes and provide insights into the molecular mechanisms of stress leading to immunosenescence.

Pharmacological Modulation of Intrarenal Pressure in a Porcine Model Using a Novel Isoprenaline-Eluting Guidewire

Introduction: Several complications of retrograde intrarenal surgery have been attributed to inadvertent increases in intrarenal pressure. We recently described the development of an innovative isoprenaline-eluting guidewire (IsoWire). The objective of this study was to investigate the impact of this IsoWire on the intrarenal pressure and evaluate its safety. Materials and Methods: This study was performed in 17 renal units using a porcine model. As controls, the intrarenal pressure, heart rate, and mean arterial pressure were measured for a duration of six minutes with a standard guidewire placed in the renal pelvis. For the experiment, the conventional guidewire was substituted with the IsoWire and the same parameters were measured. Blood samples were taken at one-minute intervals to measure plasma isoprenaline levels. This procedure was repeated on the opposite side. Results: The mean intrarenal pressure reduction was 29% (95% CI: 13%-53%). The mean isoprenaline effect time was 174 seconds. No changes in heart rate (p = .908) or mean arterial pressure (p = .749) were recorded after IsoWire insertion. Plasma isoprenaline levels were below the quantitation threshold. Isoprenaline concentrations in the plasma were below the quantification threshold. Ureteroscopy revealed no ureteral lesions. Conclusions: The IsoWire demonstrated a safe and effective reduction of intrarenal pressure. Additional research is necessary to determine whether ureteral smooth muscle relaxation generated by isoprenaline facilitates easier insertion of a ureteral access sheath, decreases the incidence of ureteral access sheath related ureteral lesions, or even encourage the practice of sheathless retrograde intrarenal surgery.

Effects of electro-mechanical uncouplers, hormonal stimulation and pacing rate on the stability and function of cultured rabbit myocardial slices

Introduction: Recent advances have enabled organotypic culture of beating human myocardial slices that are stable for weeks. However, human myocardial samples are rare, exhibit high variability and frequently originate from diseased hearts. Thus, there is a need to adapt long-term slice culture for animal myocardium. When applied to animal cardiac slices, studies in healthy or genetically modified myocardium will be possible. We present the culture of slices from rabbit hearts, which resemble the human heart in microstructure, electrophysiology and excitation-contraction coupling. Methods: Left ventricular myocardium from New Zealand White rabbits was cut using a vibratome and cultured in biomimetic chambers for up to 7 days (d). Electro-mechanical uncoupling agents 2,3-butanedione monoxime (BDM) and cytochalasin D (CytoD) were added during initiation of culture and effects on myocyte survival were quantified. We investigated pacing rates (0.5 Hz, 1 Hz, and 2 Hz) and hormonal supplements (cortisol, T3, catecholamines) at physiological plasma concentrations. T3 was buffered using BSA. Contractile force was recorded continuously. Glucose consumption and lactate production were measured. Whole-slice Ca2+ transients and action potentials were recorded. Effects of culture on microstructure were investigated with confocal microscopy and image analysis. Results: Protocols for human myocardial culture resulted in sustained contracture and myocyte death in rabbit slices within 24 h, which could be prevented by transient application of a combination of BDM and CytoD. Cortisol stabilized contraction amplitude and kinetics in culture. T3 and catecholaminergic stimulation did not further improve stability. T3 and higher pacing rates increased metabolic rate and lactate production. T3 stabilized the response to β-adrenergic stimulation over 7 d. Pacing rates above 1 Hz resulted in progredient decline in contraction force. Image analysis revealed no changes in volume fractions of cardiomyocytes or measures of fibrosis over 7 d. Ca2+ transient amplitudes and responsiveness to isoprenaline were comparable after 1 d and 7 d, while Ca2+ transient duration was prolonged after 7 d in culture. Conclusions: A workflow for rabbit myocardial culture has been established, preserving function for up to 7 d. This research underscores the importance of glucocorticoid signaling in maintaining tissue function and extending culture duration. Furthermore, BDM and CytoD appear to protect from tissue damage during the initiation phase of tissue culture.

Cola rostrata K. Schum. constituents induce cytotoxicity through reactive oxygen species generation and mitochondrial membrane depolarisation

Aim

While the traditional use of Cola rostrata in treating illnesses and diseases has not been reported, the presence of cytotoxic principles has been reported in phylogenetically and biogeographically related species within the Cola genus. This study, therefore, evaluated the cytotoxic potential of extracts of the plant, and the associated cellular and molecular mechanisms.

Methods

Activity-based fractionation of the extracts was carried out and cytotoxicity was assessed in the human cervical cancer cell line, HeLa, and the transformed human lung cell line, MRC5-SV2, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay complemented with brightfield imaging. The 2',7'-dichlorofluorescein diacetate (DCFDA) assay was used to assess induction of cellular reactive oxygen species (ROS), while flow cytometry of 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide (JC-1)-stained cells assessed the loss of mitochondrial membrane potential (∆ΨM). Gas chromatography-mass spectrometry (GC-MS) analysis was carried out on an active fraction.

Results

Extracts of the fruit epicarp and leaf were cytotoxic against the cell lines. Half-maximal inhibitory concentration (IC50) values for the 48 h cytotoxicity of the ethanol extract of the epicarp against HeLa and MRC5-SV2 cells were 48.0 μg/mL ± 12.1 μg/mL and 40.4 μg/mL ± 7.2 μg/mL, respectively, while fractions from second-level partitioning of the hexane fraction of the leaf extract elicited cytotoxicity with IC50 values ranging from 12.8 μg/mL ± 1.0 μg/mL to 39.6 μg/mL ± 7.2 μg/mL in both cell lines, following 48 h treatment. GC-MS revealed the presence of seventeen compounds in a hexane fraction of the leaf extract, including even- and odd-chain fatty acids, the most abundant of which were n-hexadecanoic acid, decanoic acid 10-(2-hexylcyclopropyl); and octadecanoic acid. The mechanisms of cytotoxicity of most active fractions involved generation of ROS and mitochondrial membrane depolarisation.

Conclusions

The findings show that C. rostrata is rich in cytotoxic phytochemicals which could be isolated for developing new anti-cancer agents.