Concentration-dependent Effect Research Articles

Influence of cashew nut shell liquid on corrosion and tribocorrosion behavior of metallic alloys

Cashew Nut Shell Liquid (CNSL) has been explored in several applications within the sustainability principles and circular economy of agro-industrial product waste. To understand the anticorrosive and lubricant properties of CNSL solutions, a multi-faceted approach, incorporating electrochemical analyses, immersion test, tribological measurements, and tribochemical characterization was carried out for mild steel AISI 1012, stainless steel AISI 420 and Aluminium Alloy 6061. Electrochemical analyses reveal a positive impact of CNSL, inducing a shift in corrosion potential to more positive values and a decrease in corrosion current, indicating effective corrosion inhibition for stainless steel and aluminium alloy. In mild steel, CNSL exhibits a mixed-type inhibition with efficiency increasing in correlation with oil concentration. The lubricating properties of CNSL are evident according to the coefficients of friction (COF) obtained and the elastohydrodynamic lubrication regime observed during tribological tests. Tribochemical tests demonstrate a reduction in wear and an improvement in tribocorrosion behavior under sliding conditions. CNSL emerges as a promising tribocorrosion mitigator, demonstrating multifaceted benefits. The concentration-dependent effects highlight the need for optimization in specific applications, particularly for passive materials. CNSL not only inhibits corrosion through film formation but also provides effective lubrication, reducing friction, wear, and chemical-mechanical degradation. This research contributes valuable insights to corrosion science. It proposes practical applications for CNSL in diverse industrial contexts, showcasing its potential as an environmentally friendly and sustainable solution for tribocorrosion challenges.

Naltrindole attenuates irreversible Hypercontracture during Myocardial Ischemia by a Novel Mechanism and elicits robust cardioprotective effects in Myocardial Ischemia/Reperfusion Injury

Introduction: Previous studies have shown that naltrindole (NTI) produced robust cardioprotective effects (e.g.~80% reduction of infarct size) in both ex-vivo (2.5-5μM) and in-vivo (3.75-7.5 mg/kg) rat myocardial ischemia-reperfusion (MIR) injury models. We recently showed that NTI 100-200μM attenuated phorbol 12-myristate 13-acetate (PMA) induced polymorphonuclear leukocytes (PMNs) superoxide (SO) release by a novel mechanism of action (MOA) devoid of opioid receptors. We hypothesize NTI’s novel MOA is a reduction of intracellular calcium (Ca2+). To test this hypothesis, we conducted PMN SO release and isolated perfused MIR assays using KB-R7943(KB). KB is known to reduce intracellular Ca2+ via inhibition of reverse mode Na+/Ca2+ exchanger and therefore should attenuate PMN SO release, myocardial ischemic hypercontracture, infarct size, and left ventricular end diastolic pressure (LVEDP). Methods: PMNs and hearts isolated from anesthetized male Sprague Dawley (SD) rats (~400g SO release assay, ~300g for perfused hearts). PMN SO release was stimulated using PMA (100nM) ± NTI 10-200 μM, KB 5-20 μM, or vehicle (0.5% DMSO; controls) and measured spectrophotometrically as a change in absorbance @ 550nm over 390 secs and cell viability was determined using 0.2% Trypan blue exclusion. We then infused NTI 1.25-5μM, KB 10-20μM, or naloxone (NX; negative control) 10μM for 5 min into perfused hearts, just prior to global I (30min)/R(45min). Cardiac LV function was measured via a pressure transducer and infarct size using 1% triphenyltetrazolium chloride staining in MIR assay. Data were analyzed using ANOVA and Fischers post-hoc analysis, with p<0.05 considered statistically significant. Results: PMN SO release assay: KB 10 μM, KB 20 μM, NTI 100 μM (~3.75 mg/kg), and NTI 200 μM(~7.5 mg/kg) significantly attenuated PMA induced PMN SO release by ~40% (KB 10μM, n=7, p<0.05), ~50% ((KB 20μM, n=7, p<0.05), ~30% (NTI 100 μM, n=7, p<0.05), 75% (NTI 200μM, n=7, p<0.05) respectively when compared to untreated control (n=10). MIR assay: NTI 5μM, 2.5μM, 1.25μM and KB 20 μM reduced infarct size (4.8±3%, n=5, p<0.05), (6.8±0.8%, n=6, p<0.05), (12.2±3%, n=5), and (2.9±2%, n=5, p<0.05) respectively compared to vehicle (14.1±2%, n=9) and NX 10μM controls (18±3%, n=3). NTI 5 μM and KB 20 μM had significantly improved LVEDP to (32.4±11%, n=5, p<0.05) and (22.8±4%, n=5, p<0.05) respectively compared to vehicle control (72.4±6%, n=9) and NX 10μM controls(54.2±8%, n=3) Conclusion: NTI and KB showed concentration-dependent effects on reducing PMN SO release. Both NTI (2.5μM, 5μM) and KB (20μM) reduced infarct size and improved LVEDP. The novel MOA of NTI is most likely mediated via a reduction in intracellular Ca2+ and subsequent hypercontracture during myocardial ischemia. The infarct reducing effect of NTI can benefit patients who will undergo elective PCI, CABG, and transplants. Funding: This study was funded by the Philadelphia College of Osteopathic Medicine, Department of Biomedical Sciences, Division of Research, and the Center for Chronic Diseases of Aging and Young Therapeutics, LLC. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

THE BIOCHEMICAL RESPONSES OF BIVALVE MOLLUSCS TO NEUROLEPTIC CHLORPROMAZINE ARE COMPARABLE WITH THE RESPONSES OF HIGHER VERTEBRATES

Pharmaceuticals such as chlorpromazine (Cpz) are emerging aquatic pollutants with potential effects on non-target organisms. However, its effects on aquatic organisms remain limited and inconclusive. The aim of this study was to compare the responses to Cpz in marine and freshwater bivalve molluscs. Methods. Mytilus galloprovincialis and Unio tumidus were exposed to pM and nM concentrations of Cpz for 14 days and analysed 16 parameters, including cytotoxicity, oxidative/reductive stress responses, metallothionein concentration and biotransformation enzymes in the digestive gland. Results. In both species, Cpz increased EROD activity, possibly leading to the formation of reactive metabolites. Marine mussels exposed to Cpz I and II showed increased GST activity, suggesting detoxification, whereas freshwater mussels showed decreased GST activity, suggesting higher Cpz toxicity. Activation of the GTPase dynamin in U. tumidus exposed to Cpz I confirmed the effect of Cpz on endocytosis. Oxidative stress responses were observed in both species, with changes in oxidative/reductive stress responses, suggesting toxic effects of Cpz. GSH and metallothionein concentrations increased in all exposures, while the NADH/NAD+ ratio increased significantly in U. tumidus. Loss of lysosomal membrane stability was observed in all exposed groups, with CtD efflux detected only in mussels. Differences in caspase-3 activity were also observed between species. Conclusion. Cpz showed adverse effects on vertebrates at μM concentrations, while mussels were affected at pM to nM concentrations, indicating concentration-dependent interspecies effects. Stress responses were similar between species, suggesting that marine molluscs are a potential model for assessing the adverse effects of Cpz on higher vertebrates.

Cerric ammonium nitrate catalyzed eco-friendly green synthesis of chitosan Schiff base using PEG-400 as an anticancer agent against gastric cancer cells via inhibiting EGFR

The present study was conducted to scrutinize the pharmacological effect of oxazole-embedded Chitosan as an anticancer agent against gastric cancer cells. This compound was synthesized using the classical Schiff base reaction but utilizing the novel green chemical process where cerric ammonium nitrate (CAN) was used as a catalyst in the PEG-400 as solvent media. The target compound was obtained with an excellent yield at the catalyst loading of 5% CAN concentration in 15 min. The Kinase-Glo Plus luminescence kinase assay kit was used to determine the EGFR inhibitory activity of compound 1 where it showed potent activity with IC50 of 2.14 µM. Its effect was also determined on the cellular viability of the Human gastric cancer cell line (SGC7901), liver cancer cell line (HepG2), and lung cancer cell line (A549), where it exhibits potent activity against SGC7901. The compound further showed the concentration-dependent inhibitory effect on migration and invasion of SGC7901. In RT-qPCR analysis, the compound showed induction of apoptosis of SGC7901 cells possibly by restoring the expression of Bcl-2 and Bax near to normal, and inhibition of the mRNA expression of EGFR in a concentration-dependent manner. KEY WORDS: Schiff base, Chitosan, EGFR, mRNA, apoptosis, Bcl-2 Bull. Chem. Soc. Ethiop. 2024, 38(4), 1091-1101. DOI: https://dx.doi.org/10.4314/bcse.v38i4.22

Evaluating The Cytotoxic Activity of Lactobacillus plantarum IIA-1A5 Against MCF-7 Human Breast Cancer Cells and Identifying Its Surface Layer Protein Gene

Breast cancer is a serious global health concern, with a high mortality rate worldwide. Using natural compounds as potential cancer therapies is a promising approach to address this issue. Previous research has shown that probiotic lactic acid bacteria (LAB) and their metabolites, such as surface layer protein (slp), have a positive impact on a variety of health disorders, including cancer. The purpose of this study was to evaluate the ability of Lactobacillus plantarum IIA-1A5 to suppress the growth of the MCF-7 breast cancer cell line and detect the presence of the slp gene. Intracellular and extracellular protein fractions were isolated from L. plantarum IIA-1A5 cultures. The protein concentrations and molecular weights of the extracts were measured. The anticancer activity of the extracts was assessed using the MTT cytotoxicity test, and IC50 values were calculated. The slp gene was identified through polymerase chain reaction (PCR) amplification and nucleotide sequencing. The results demonstrated that L. plantarum IIA-1A5 had a concentration-dependent inhibitory effect on MCF-7 breast cancer cells, with IC50 values of 6.831 and 12.35 μg/mL for intracellular extracts and extracellular extracts, respectively. Additionally, PCR amplification and nucleotide sequencing confirmed the presence of the slp gene, which may contribute to the strain’s anticancer abilities. These findings suggest the potential of L. plantarum IIA-1A5 as a natural anticancer agent against MCF-7 breast cancer cells. Further research is warranted to elucidate the underlying mechanisms of L. plantarum IIA-1A5 in breast cancer treatment.

Enhanced and copper concentration dependent virucidal effect against SARS-CoV-2 of electrospun poly(vinylidene difluoride) filter materials

Virucidal filter materials were prepared by electrospinning a solution of 28 wt% poly(vinylidene difluoride) in N,N-dimethylacetamide without and with the addition of 0.25 wt%, 0.75 wt%, 2.0 wt%, or 3.5 wt% Cu(NO3)2 · 2.5H2O as virucidal agent. The fabricated materials had a uniform and defect free fibrous structure and even distribution of copper nanoclusters. X-ray diffraction analysis showed that during the electrospinning process, Cu(NO3)2 · 2.5H2O changed into Cu2(NO3)(OH)3. Electrospun filter materials obtained by electrospinning were essentially macroporous. Smaller pores of copper nanoclusters containing materials resulted in higher particle filtration than those without copper nanoclusters. Electrospun filter material fabricated with the addition of 2.0 wt% and 3.5 wt% of Cu(NO3)2 · 2.5H2O in a spinning solution showed significant virucidal activity, and there was 2.5± 0.35 and 3.2± 0.30 logarithmic reduction in the concentration of infectious SARS-CoV-2 within 12 h, respectively. The electrospun filter materials were stable as they retained virucidal activity for three months.

Modeling temperature-dependent life-cycle toxicity of thiamethoxam in Chironomus riparius using a DEB-TKTD model

The neonicotinoid insecticide thiamethoxam (TMX) is widely used to protect crops against insect pests. Despite some desirable properties such as its low toxicity to birds and mammals, concerns have been raised about its toxicity to non-target arthropods, including freshwater insects like chironomids. Whereas multiple studies have investigated chronic effects of neonicotinoids in chironomid larvae at standardized laboratory conditions, a better understanding of their chronic toxicity under variable temperatures and exposure is needed for coherent extrapolation from the laboratory to the field. Here, we developed a quantitative mechanistic effect model for Chironomus riparius, to simulate the species’ life history under dynamic temperatures and exposure concentrations of TMX. Laboratory experiments at four different temperatures (12, 15, 20, 23 °C) and TMX concentrations between 4 and 51 µg/L were used to calibrate the model. Observed concentration-dependent effects of TMX in C. riparius included slower growth, later emergence, and higher mortality rates with increasing concentrations. Furthermore, besides a typical accelerating effect on the organisms’ growth and development, higher temperatures further increased the effects associated with TMX. With some data-informed modeling decisions, most prominently the inclusion of a size dependence that makes larger animals more sensitive to TMX, the model was parametrized to convincingly reproduce the data. Experiments at both a constant (20 °C) and a dynamically increasing temperature (15–23 °C) with pulsed exposure were used to validate the model. Finally, the model was used to simulate realistic exposure conditions using two reference exposure scenarios measured in Missouri and Nebraska, utilizing a moving time window (MTW) and either a constant temperature (20 °C) or the measured temperature profiles belonging to each respective scenario. Minimum exposure multiplication factors leading to a 10% effect (EP10) in the survival at pupation, i.e., the most sensitive endpoint found in this study, were 25.67 and 21.87 for the Missouri scenario and 38.58 and 44.64 for the Nebraska scenario, when using the respective temperature assumptions. While the results illustrate that the use of real temperature scenarios does not systematically modify the EPx in the same direction (making it either more or less conservative when used as a risk indicator), the advantage of this approach is that it increases the realism and thus reduces the uncertainty associated with the model predictions.

Long-term tributyltin exposure alters behavior, oocyte maturation, and histomorphology of the ovary due to oxidative stress in adult zebrafish

Tributyltin (TBT), an organotin endocrine-disrupting substance, is recognized as one of the important toxic environmental pollutants. The present study was carried out to investigate the toxic effects of TBT on behavior and the ovary of adult zebrafish with a focus on oxidative stress markers and oocyte maturation. Adult zebrafish were exposed to three different concentrations (125, 250, and 500 ng/L of water) of TBT for 28 days. TBT exposure produced a concentration-dependent negative effect on the body weight and behavior (anxiety-like symptoms) of adult zebrafish. Alterations in the activity of superoxide dismutase (SOD) and catalase (CAT), the total antioxidant capacity of ovarian tissue by the highest exposure level of TBT resulted in lipid peroxidation as indicated by increased malondialdehyde (MDA) level. The numbers of early-vitellogenic oocytes were significantly increased in zebrafish exposed to TBT as low as 125 ng/L. However, the numbers and size of fully-grown (mature) oocytes were significantly reduced in the highest exposure group only. Correlation between the MDA level and pre-vitellogenic oocytes in the 500 ng/L group indicated that lipid peroxidation prevented the maturation of pre-vitellogenic oocytes. TBT exposure produced significant histological changes in the ovary as evidenced by disturbed maturation of oocytes. In conclusion, TBT adversely affected the maturation of oocytes in zebrafish ovary through oxidative stress-mediated mechanisms.

A Multi-Drug Concentration Gradient Mixing Chip: A Novel Platform for High-Throughput Drug Combination Screening.

Combinatorial drug therapy has emerged as a critically important strategy in medical research and patient treatment and involves the use of multiple drugs in concert to achieve a synergistic effect. This approach can enhance therapeutic efficacy while simultaneously mitigating adverse side effects. However, the process of identifying optimal drug combinations, including their compositions and dosages, is often a complex, costly, and time-intensive endeavor. To surmount these hurdles, we propose a novel microfluidic device capable of simultaneously generating multiple drug concentration gradients across an interlinked array of culture chambers. This innovative setup allows for the real-time monitoring of live cell responses. With minimal effort, researchers can now explore the concentration-dependent effects of single-agent and combination drug therapies. Taking neural stem cells (NSCs) as a case study, we examined the impacts of various growth factors-epithelial growth factor (EGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF)-on the differentiation of NSCs. Our findings indicate that an overdose of any single growth factor leads to an upsurge in the proportion of differentiated NSCs. Interestingly, the regulatory effects of these growth factors can be modulated by the introduction of additional growth factors, whether singly or in combination. Notably, a reduced concentration of these additional factors resulted in a decreased number of differentiated NSCs. Our results affirm that the successful application of this microfluidic device for the generation of multi-drug concentration gradients has substantial potential to revolutionize drug combination screening. This advancement promises to streamline the process and accelerate the discovery of effective therapeutic drug combinations.

Effects of an environmentally relevant mixture of organochlorine pesticide compounds on adipogenesis and adipocyte function in an immortalized human adipocyte model

Exposure to persistent organic pollutants (POPs), including organochlorine (OC) pesticide POPs, has been associated with the increased prevalence of obesity and type 2 diabetes. However, the underlying mechanisms through which exposure to these compounds may promote obesity and metabolic dysfunction remain an area of active investigation. To this end, the concentration dependent effects of an environmentally relevant mixture of OC pesticide POPs on adipocyte function was explored utilizing a translationally relevant immortalized human subcutaneous preadipocyte/adipocyte model. Briefly, immortalized human preadipocytes/adipocytes were exposed to a mixture of dichlorodiphenyldichloroethylene (DDE), trans-nonachlor, and oxychlordane (DTO) then key indices of preadipocyte/adipocyte function were assessed. Exposure to DTO did not alter adipogenesis. However, in mature adipocytes, exposure to DTO slightly increased fatty acid uptake whereas isoproterenol stimulated lipolysis, basal and insulin stimulated glucose uptake, mitochondrial membrane potential, and cellular ATP levels were all significantly decreased. DTO significantly increased Staphylococcus aureus infection induced increases in expression of pro-inflammatory cytokines IL-6, IL-1β, and Mcp-1 as well as the adipokine resistin. Taken together, the present data demonstrated exposure to an environmentally relevant mixture of OC pesticide compounds can alter mature adipocyte function in a translationally relevant human adipocyte model which further supports the adipose tissue as an effector site of OC pesticide POPs action.

The Vasodilator Effect and Mechanism of 18β-glycyrrhetinic Acid on Isolated Pulmonary Artery Rings in Rats

Background: The purpose of this study was to evaluate the effect of 18β-glycyrrhetinic acid (18β-GA) on isolated rat pulmonary artery vascular rings as well as the mechanism that lies behind the diastolic effects of this compound. Methods: To examine the effects of various doses of 18β-GA on resting normal vascular rings, we used isolated rat pulmonary artery vascular rings. The isolated rat pulmonary artery vascular ring was precontracted with phenylephrine (PE) and potassium chloride solution (KCl), which allowed for the observation of the diastolic effects of 18β-GA, as well as the effects of various concentrations of 18β-GA on blocking the four potassium channels of glibenclamide, barium chloride (BaCl2), tetraethylamine (TEA), or 4-aminopyridine; the impact of various 18β-GA concentrations on the pulmonary artery vasodilation effect pre-use of the nitric oxide synthase inhibitors l-nitroarginine methyl ester and indomethacin. Results: It was shown that 18β-GA has concentration-dependent diastolic effects on isolated rat pulmonary vascular rings that have been precontracted with PE and KCl but it has no effect on resting isolated thoracic aortic vascular rings. Conclusion: The two Kir and Kv channels may be connected to the endothelium-dependent vasodilation mechanism of 18β-GA.

Library screening identifies commercial drugs as potential structure correctors of abnormal apolipoprotein A-I

AapoA-I, the main protein of high-density lipoprotein, plays a key role in the biogenesis and atheroprotective properties of high-density lipoprotein. We showed previously that a naturally occurring apoA-I mutation, L178P, induces major defects in protein’s structural integrity and functions that may underlie the increased cardiovascular risk observed in carriers of the mutation. Here, a library of marketed drugs (956 compounds) was screened against apoA-I[L178P] to identify molecules that can stabilize the normal conformation of apoA-I. Screening was performed by the thermal shift assay in the presence of fluorescent dye SYPRO Orange. As an orthogonal assay, we monitored the change in fluorescence intensity of 8-anilinonaphthalene-1-sulfonic acid upon binding on hydrophobic sites on apoA-I. Screening identified four potential structure correctors. Subsequent analysis of the concentration-dependent effect of these compounds on secondary structure and thermodynamic stability of WT apoA-I and apoA-I[L178P] (assessed by thermal shift assay and circular dichroism spectroscopy), as well as on macrophage viability, narrowed the potential structure correctors to two, the drugs atorvastatin and bexarotene. Functional analysis showed that these two compounds can restore the defective capacity of apoA-I[L178P] to promote cholesterol removal from macrophages, an important step for atheroprotection. Computational docking suggested that both drugs target a positively charged cavity in apoA-I, formed between helix 1/2 and helix 5, and make extensive interactions that could underlie thermodynamic stabilization. Overall, our findings indicate that small molecules can correct defective apoA-I structure and function and may lead to novel therapeutic approaches for apoA-I–related dyslipidemias and increased cardiovascular risk.

Synergistic effects of β-NaFeO2 ferrite nanoparticles for photocatalytic degradation, antibacterial, and antioxidant applications.

Here, synthesis and thorough characterization of β-NaFeO2 nanoparticles utilizing a co-precipitation technique is presented. XRD analysis confirmed a hexagonal-phase structure of β-NaFeO2. SEM revealed well-dispersed spherical nanoparticles with an average diameter of 45 nm. The FTIR spectrum analysis revealed weak adsorption bands at 1054 cm-1 suggested metal-metal bond stretching (Fe-Na). UV-Visible spectroscopy indicates a 4.4 eV optical band gap. Colloidal stability of β-NaFeO2 was evidenced via Zeta potential (-28.5 mV) and Dynamic Light Scattering (DLS) measurements. BET analysis reveals a substantial 343.27 m2 g-1 surface area with mesoporous characteristics. Antioxidant analysis indicates efficacy comparable to standard antioxidants, while concentration-dependent antibacterial effects suggest enhanced efficacy against Gram-positive bacteria, particularly Streptococcus. The Photocatalytic activity of β-NaFeO2 showed significant pollutant degradation (>90% efficiency), with increased degradation rates at higher nanoparticle concentrations, indicating potential for environmental remediation applications.

Antioxidant capacity, anti-inflammatory activity, and mutagenicity of Sterculia lychnophora (Pangdahai) polysaccharide

Dried boat-fruited ripped seeds of Sterculia lychnophora, commonly known as Pangdahai, are frequently used in traditional Chinese medicines and functional foods. However, research on these constituents is limited. In this study, the extraction of Pangdahai polysaccharide (PP) was investigated using different solvents (deionized water, 50 % methanol, and 50 % ethanol), and its chemical composition, antioxidant capacity, and anti-inflammatory activity were analyzed. Additionally, the Ames test was used to evaluate PPs’ food safety and mutagenicity. The results showed that the yields of PPs extracted with the three solvents ranged from ∼ 19 % to 21 % and that their monosaccharide compositions (rhamnose, arabinose, galactose, and glucose) were similar, with slightly different proportions. Moreover, the antioxidant capacity of all three PPs showed concentration-dependent effects. The EC50 values for each antioxidant were approximately 0.71–1.35 mg/mL for 1, 1-diphenyl-2-picrylhydrazyl free radical scavenging ability, 1.88–46.13 µg/mL for 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging ability, 2.22–3.61 mg/mL for ferric reducing antioxidant power, and 0.52–3.11 mg/mL for hydroxyl radical scavenging ability. At concentrations below 500 µg/mL, the anti-inflammator activity of PPs promoted cell proliferation while inhibiting nitric oxide production at concentrations ranging from 31.25 to 125 µg/mL. In the Ames test, PPs (1–5 mg/plate) exhibited no toxicity or mutagenicity against the five strains of Salmonella typhimurium (TA98, TA100, TA102, TA1535, and TA1537). These findings will particularly be of interest to individuals involved in PP-related research or commercial enterprises. Thus, the findings of this study will elucidate the bioactive components and potential benefits of PP, making it especially valuable to researchers and practitioners in the Pangdahai industry and expanding opportunities for industrial development.

Acute toxicity of rich triethylene glycol on juvenile African freshwater catfish (Clarias gariepinus) around a natural gas dehydration facility

Triethylene glycol (TEG) removes equilibrium water from natural gas but may spill during equipment maintenance and other poor safety practices. Studies on the toxicity of rich TEG in aquatic habitats are scarce. In this study, the toxicity of rich TEG on freshwater juvenile African catfish (Clarias gariepinus) test organism was conducted. The experimental design for the toxicity tests was 3 × 5 × 6 factor in a randomized complete block design, with six levels of treatment, observed at five intervals and in three replicates. The acute toxicity was carried out by exposing them to various lethal concentrations of the Rich TEG in solution. Physicochemical parameters, including temperature, dissolved oxygen, pH, conductivity, and total dissolved solids, were measured and recorded for five test concentrations of 25.92, 12.96, 6.48, 3.24, 1.62, and 0.0 ml/l (control). The concentration responses for the fish mortality at 24, 48, 72, and 96 h were also derived. No mortality was observed between Rich TEG concentrations of 0 ml/l to 25.92 ml/l after 72 h of exposure. However, some mortality was observed between 1.62 ml/l to 25.92 ml/l after 96 h of exposure. The highest concentration of 25.92 ml/l recorded a higher mortality of 6.0 ± 0.4, which is an average of 60%, while the lowest mortality was recorded in the control (0 ml/l), at an average of 0% mortality rate. The results underscore the concentration-dependent effects of rich TEG on the test organism, highlighting the need for targeted attention to higher concentration levels.

Membrane potential dynamics of C5a-stimulated neutrophil granulocytes

Neutrophil granulocytes play a crucial role in host defense against invading pathogens and in inflammatory diseases. The aim of this study was to elucidate membrane potential dynamics during the initial phase of neutrophil activation and its relation to migration and production of reactive oxygen species (ROS). We performed ROS production measurements of neutrophils from healthy C57BL/6J mice after TNFα-priming and/or C5a stimulation. The actin cytoskeleton was visualized with fluorescence microscopy. Furthermore, we combined migration assays and measurements of membrane potential dynamics after stimulating unprimed and/or TNFα-primed neutrophils with C5a. We show that C5a has a concentration-dependent effect on ROS production and chemokinetic migration. Chemokinetic migration and chemotaxis are impaired at C5a concentrations that induce ROS production. The actin cytoskeleton of unstimulated and of ROS-producing neutrophils is not distributed in a polarized way. Inhibition of the phagocytic NADPH oxidase NOX2 with diphenyleneiodonium (DPI) leads to a polarized distribution of the actin cytoskeleton and rescues chemokinetic migration of primed and C5a-stimulated neutrophils. Moreover, C5a evokes a pronounced depolarization of the cell membrane potential by 86.6 ± 4.2 mV starting from a resting membrane potential of -74.3 ± 0.7 mV. The C5a-induced depolarization occurs almost instantaneously (within less than one minute) in contrast to the more gradually developing depolarization induced by PMA (lag time of 3—4 min). This initial depolarization is accompanied by a decrease of the migration velocity. Collectively, our results show that stimulation with C5a evokes parallel changes in membrane potential dynamics, neutrophil ROS production and motility. Notably, the amplitude of membrane potential dynamics is comparable to that of excitable cells.

Vasorelaxant and Blood Pressure-Lowering Effects of Cnidium monnieri Fruit Ethanol Extract in Sprague Dawley and Spontaneously Hypertensive Rats.

Cnidium monnieri (L.) Cusson, a member of the Apiaceae family, is rich in coumarins, such as imperatorin and osthole. Cnidium monnieri fruit (CM) has a broad range of therapeutic potential that can be used in anti-bacterial, anti-cancer, and sexual dysfunction treatments. However, its efficacy in lowering blood pressure through vasodilation remains unknown. This study aimed to assess the potential therapeutic effect of CM 50% ethanol extract (CME) on hypertension and the mechanism of its vasorelaxant effect. CME (1-30 µg/mL) showed a concentration-dependent vasorelaxation on constricted aortic rings in Sprague Dawley rats induced by phenylephrine via an endothelium-independent mechanism. The vasorelaxant effect of CME was inhibited by blockers of voltage-dependent and Ca2+-activated K+ channels. Additionally, CME inhibited the vascular contraction induced by angiotensin II and CaCl2. The main active compounds of CM, i.e., imperatorin (3-300 µM) and osthole (1-100 µM), showed a concentration-dependent vasorelaxation effect, with half-maximal effective concentration values of 9.14 ± 0.06 and 5.98 ± 0.06 µM, respectively. Orally administered CME significantly reduced the blood pressure of spontaneously hypertensive rats. Our research shows that CME is a promising treatment option for hypertension. However, further studies are required to fully elucidate its therapeutic potential.

Bioactive Properties of Venoms Isolated from Whiptail Stingrays and the Search for Molecular Mechanisms and Targets.

The venom-containing barb attached to their 'whip-like' tail provides stingrays a defensive mechanism for evading predators such as sharks. From human encounters, dermal stingray envenomation is characterized by intense pain often followed by tissue necrosis occurring over several days to weeks. The bioactive components in stingray venoms (SRVs) and their molecular targets and mechanisms that mediate these complex responses are not well understood. Given the utility of venom-derived proteins from other venomous species for biomedical and pharmaceutical applications, we set out to characterize the bioactivity of SRV extracts from three local species that belong to the Dasyatoidea 'whiptail' superfamily. Multiple cell-based assays were used to quantify and compare the in vitro effects of these SRVs on different cell lines. All three SRVs demonstrated concentration-dependent growth-inhibitory effects on three different human cell lines tested. In contrast, a mouse fibrosarcoma cell line was markedly resistant to all three SRVs, indicating the molecular target(s) for mediating the SRV effects are not expressed on these cells. The multifunctional SRV responses were characterized by an acute disruption of cell adhesion leading to apoptosis. These findings aim to guide future investigations of individual SRV proteins and their molecular targets for potential use in biomedical applications.

Concentration-Dependent Effects of Curcumin on Membrane Permeability and Structure.

Growing evidence suggests that many bioactive molecules can nonspecifically modulate the physicochemical properties of membranes and influence the action of embedded membrane proteins. This study investigates the interactions of curcumin with protein-free model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and DOPC with cholesterol (4/1 mol ratio). The focus is on the capability of curcumin to modify membrane barrier properties such as water permeability assayed through the droplet interface bilayer (DIB) model membrane. For pure DOPC, our findings show a concentration-dependent biphasic effect: a reduction in water permeability is observed at low concentrations (up to 2 mol %), whereas at high concentrations of curcumin, water permeability increases. In the presence of cholesterol, we observed an overall reduction in water permeability. A combination of complementary experimental methods, including phase transition parameters studied by differential scanning calorimetry (DSC) and structural properties measured by attenuated total reflectance (ATR)-FTIR, provides a deeper understanding of concentration-dependent interactions of curcumin with DOPC bilayers in the absence and presence of cholesterol. Our experimental findings align with a molecular mechanism of curcumin's interaction with model membranes, wherein its effect is contingent on its concentration. At low concentrations, curcumin binds to the lipid-water interface through hydrogen bonding with the phosphate headgroup, thereby obstructing the transport of water molecules. Conversely, at high concentrations, curcumin permeates the acyl chain region, inducing packing disorders and demonstrating evidence of phase separation. Enhanced knowledge of the impact of curcumin on membranes, which, in turn, can affect protein function, is likely to be beneficial for the successful translation of curcumin into effective medicine.

β-Cell-selective regulation of gene expression by nitric oxide.

Nitric oxide is produced at low micromolar levels following the induction of inducible nitric oxide synthase (iNOS) and is responsible for mediating the inhibitory actions of cytokines on glucose-stimulated insulin secretion by islets of Langerhans. It is through the inhibition of mitochondrial oxidative metabolism, specifically aconitase and complex 4 of the electron transport chain, that nitric oxide inhibits insulin secretion. Nitric oxide also attenuates protein synthesis, induces DNA damage, activates DNA repair pathways, and stimulates stress responses (unfolded protein and heat shock) in β-cells. In this report, the time- and concentration-dependent effects of nitric oxide on the expression of six genes known to participate in the response of β-cells to this free radical were examined. The genes included Gadd45α (DNA repair), Puma (apoptosis), Hmox1 (antioxidant defense), Hsp70 (heat shock), Chop (UPR), and Ppargc1α (mitochondrial biogenesis). We show that nitric oxide stimulates β-cell gene expression in a narrow concentration range of ∼0.5-1 µM or levels corresponding to iNOS-derived nitric oxide. At concentrations greater than 1 µM, nitric oxide fails to stimulate gene expression in β-cells, and this is associated with the inhibition of mitochondrial oxidative metabolism. This narrow concentration range of responses is β-cell selective, as the actions of nitric oxide in non-β-cells (α-cells, mouse embryonic fibroblasts, and macrophages) are concentration dependent. Our findings suggest that β-cells respond to a narrow concentration range of nitric oxide that is consistent with the levels produced following iNOS induction, and that these concentration-dependent actions are selective for insulin-containing cells.