Combined antiproliferative activity of imatinib mesylate (STI-571) with radiation or cisplatin in vitro

Little is known about the interaction of novel anticancer drugs with other treatment modalities. The aim of this study was to examine the effect of combining imatinib mesylate (STI-571) with radiation or cisplatin on the survival of two human solid tumor cell lines – SKNMC cells derived from Ewing sarcoma and breast cancer MCF-7 cells. Methods: Cell proliferation was determined using the sulphorodamine B cytotoxicity assay. Cell cycle analysis was performed with flow cytometry. Apoptosis was determined using a commercial cell death ELISA plus kit. Phosphorylated AKT, which has been suggested to be involved in radiation resistance, was detected by Western blot analysis. Results: Exposure of SKNMC cells to STI-571 resulted in a dose-dependent antiproliferative effect and a decrease in phosphorylated AKT expression. There was no evidence of apoptosis. The combination of STI-571 with radiation or cisplatin had an additive antiproliferative effect in SKNMC cells (60% reduction in cell number). A similar effect was observed in human MCF-7 breast cancer cells. Conclusion: STI-571 improves the outcome of cisplatin or irradiation treatment in vitro. AKT pathway may play a role in the additive effect of STI-571 and irradiation.Цель: оценить антипролиферативный эффект иматиниба (STI-571) в комбинации с облучением или цисплатиной по отношению к двум клеточным линиям – клеткам линии SKNMC, полученным из саркомы Эвинга, и клеткам рака молочной железы человека линии MCF-7. Методы: для оценки пролиферации клеток применяли метод анализа цитотоксичности с использованием сульфородамина B. Для анализа распределения клеток по фазам клеточного цикла применяли метод проточной цитометрии, апоптоза – с применением коммерческого набора для проведения ИФА. Уровень фосфорилированной киназы АКТ, предположительно связанной с радиорезистентностью, определяли методом Вестерн-блот анализа. Результаты: инкубация клеток SKNMC STI-571 приводила к дозозависимому антипролиферативному эффекту и снижению фосфорилирования AKT, но не апоптозу клеток. Комбинированное применение STI-571 и обления или цисплатины оказывало дополнительное антипролиферативное воздействие на клетки линии SKNMC (60% уменьшения количества клеток). Аналогичные эффекты отмечали на клетках линии MCF-7. Выводы: обработка опухолевых клеток STI-571 усиливает эффект обления и цисплатины in, причем таковой может быть опосредован сигнальным каскадом AK

Asymmetric protonation of EmrE

The small multidrug resistance transporter EmrE is a homodimer that uses energy provided by the proton motive force to drive the efflux of drug substrates. The pKa values of its “active-site” residues—glutamate 14 (Glu14) from each subunit—must be poised around physiological pH values to efficiently couple proton import to drug export in vivo. To assess the protonation of EmrE, pH titrations were conducted with (1)H-(15)N TROSY-HSQC nuclear magnetic resonance (NMR) spectra. Analysis of these spectra indicates that the Glu14 residues have asymmetric pKa values of 7.0 ± 0.1 and 8.2 ± 0.3 at 45°C and 6.8 ± 0.1 and 8.5 ± 0.2 at 25°C. These pKa values are substantially increased compared with typical pKa values for solvent-exposed glutamates but are within the range of published Glu14 pKa values inferred from the pH dependence of substrate binding and transport assays. The active-site mutant, E14D-EmrE, has pKa values below the physiological pH range, consistent with its impaired transport activity. The NMR spectra demonstrate that the protonation states of the active-site Glu14 residues determine both the global structure and the rate of conformational exchange between inward- and outward-facing EmrE. Thus, the pKa values of the asymmetric active-site Glu14 residues are key for proper coupling of proton import to multidrug efflux. However, the results raise new questions regarding the coupling mechanism because they show that EmrE exists in a mixture of protonation states near neutral pH and can interconvert between inward- and outward-facing forms in multiple different protonation states

The effect of cold acclimation on active ion transport in cricket ionoregulatory tissues.

Cold-acclimated insects defend ion and water transport function during cold exposure. We hypothesized that this is achieved via enhanced active transport. The Malpighian tubules and rectum are likely targets for such transport modifications, and recent transcriptomic studies indicate shifts in Na+-K+ ATPase (NKA) and V-ATPase expression in these tissues following cold acclimation. Here we quantify the effect of cold acclimation (one week at 12 °C) on active transport in the ionoregulatory organs of adult Gryllus pennsylvanicus field crickets. We compared primary urine production of warm- and cold-acclimated crickets in excised Malpighian tubules via Ramsay assay at a range of temperatures between 4 and 25 °C. We then compared NKA and V-ATPase activities in Malpighian tubule and rectal homogenates from warm- and cold-acclimated crickets via NADH-linked photometric assays. Malpighian tubules of cold-acclimated crickets excreted fluid at lower rates at all temperatures compared to warm-acclimated crickets. This reduction in Malpighian tubule excretion rates may be attributed to increased NKA activity that we observed for cold-acclimated crickets, but V-ATPase activity was unchanged. Cold acclimation had no effect on rectal NKA activity at either 21 °C or 6 °C, and did not modify rectal V-ATPase activity. Our results suggest that an overall reduction, rather than enhancement of active transport in the Malpighian tubules allows crickets to maintain hemolymph water balance during cold exposure, and increased Malpighian tubule NKA activity may help to defend and/or re-establish ion homeostasis

The Cost of (Un)regulation: Shrinking Earth’s Orbits and the Need for Sustainable Space Governance

Steph Paladini: ORCID: 0000-0002-1526-3589 https://orcid.org/0000-0002-1526-3589Outer space is infinite, useable planetary orbits are not. This makes the Earth's orbit a unique case of an Area Beyond National Jurisdiction (ABNJ) complex to address, difficult to use in a sustainable and equitable way and almost intractable to regulate at an international level. As of 2023, we remain far from attaining a sustainable orbital environment, and future uses of the Earth's orbits for new satellites constellations appear now increasingly at risk. Adopting a probability-based empirical model to project the growth trajectory of objects in space, this article argues that the sector will cross a 'critical density' threshold within the upcoming years unless strong remedial actions to clear up the orbits are implemented and estimates the potential costs of active debris removal measures. Our findings suggest that orbital sustainability is unlikely to come from technology alone, no matter how advanced or ground-breaking. A long-term solution will necessarily require a radical rewriting of the outdated, often conflicting international regulatory framework, which contributed to creating this debris crisis in the first place, shrinking the Earth's orbit to (almost) the point of no return.pubpu

Inevitable Evolutionary Temporal Elements in Neural Processing: A Study Based on Evolutionary Simulations

Recent studies have suggested that some neural computational mechanisms are based on the fine temporal structure of spiking activity. However, less effort has been devoted to investigating the evolutionary aspects of such mechanisms. In this paper we explore the issue of temporal neural computation from an evolutionary point of view, using a genetic simulation of the evolutionary development of neural systems. We evolve neural systems in an environment with selective pressure based on mate finding, and examine the temporal aspects of the evolved systems. In repeating evolutionary sessions, there was a significant increase during evolution in the mutual information between the evolved agent's temporal neural representation and the external environment. In ten different simulated evolutionary sessions, there was an increased effect of time -related neural ablations on the agents' fitness. These results suggest that in some fitness landscapes the emergence of temporal elements in neural computation is almost inevitable. Future research using similar evolutionary simulations may shed new light on various biological mechanisms

Evolving Synaptic Plasticity with an Evolutionary Cellular Development Model

Since synaptic plasticity is regarded as a potential mechanism for memory formation and learning, there is growing interest in the study of its underlying mechanisms. Recently several evolutionary models of cellular development have been presented, but none have been shown to be able to evolve a range of biological synaptic plasticity regimes. In this paper we present a biologically plausible evolutionary cellular development model and test its ability to evolve different biological synaptic plasticity regimes. The core of the model is a genomic and proteomic regulation network which controls cells and their neurites in a 2D environment. The model has previously been shown to successfully evolve behaving organisms, enable gene related phenomena, and produce biological neural mechanisms such as temporal representations. Several experiments are described in which the model evolves different synaptic plasticity regimes using a direct fitness function. Other experiments examine the ability of the model to evolve simple plasticity regimes in a task -based fitness function environment. These results suggest that such evolutionary cellular development models have the potential to be used as a research tool for investigating the evolutionary aspects of synaptic plasticity and at the same time can serve as the basis for novel artificial computational systems