Biology subjects

Rust, S.

Publications and source records attributed to Rust, S..

10 recordsLinked to original sources

bioRxiv2026

Low impact of internal stem decay on forest carbon stocks in fire-prone Pinus ponderosa forests

Large old trees are of eminent importance for organic carbon storage in forest ecosystems and thus play a role in mitigating climate change. Such trees also have an increased risk of internal stem decay and tree cavity formation, which promotes biodiversity, but complicates the prediction of their biomass and carbon stocks, which is usually done from stem diameter and tree height data applying allometric biomass functions. Since the extent of internal stem decay is known to vary widely between different forest ecosystems and data from moist temperate forests exhibited low significance of internal stem decay, we studied dry, frequently fire-exposed Pinus ponderosa forests in central Oregon to capture the other climatic extreme of temperate forests. We hypothesized high significance of internal stem decay for stand aboveground tree biomass, as we assumed widespread stem injury from fire. In addition, we tested the hypothesis that far more than the largest 1% of trees are necessary for 50% stand biomass, as this hypothesis is found in the literature, but has been challenged in other studies. We found low biomass loss due to internal stem decay by only ca. 1% suggesting that also for fire-prone temperate forests of western North America, biomass estimates based on allometric regression are reliable. The 1% largest trees-50% stand aboveground biomass hypothesis has to be rejection for our forests as long as only trees of a size are included that noteworthily contribute to stand biomass. This metrics strongly depends on regeneration density, which is not relevant for stand biomass.

ecology↗

bioRxiv2024

Visualization of Type IV-A1 CRISPR-mediated repression of gene expression and plasmid replication

Type IV CRISPR-Cas effector complexes are often encoded on plasmids and are proposed to prevent the replication of competing plasmids. The Type IV-A1 CRISPR-Cas system of Pseudomonas oleovorans additionally harbors a CRISPR RNA (crRNA) that tightly regulates the transcript levels of a chromosomal target and represents a natural CRISPR interference (CRISPRi) tool. This study investigates CRISPRi effects of this system using synthetic crRNAs against genome and plasmid sequences. Targeting of reporter genes revealed extended interference in P. oleovorans and Escherichia coli cells producing recombinant CRISPR ribonucleoprotein (crRNP) complexes. RNA-Seq analyses of Type IV-A1 CRISPRi-induced transcriptome alterations demonstrated highly effective long-range down-regulation of histidine operon expression, whereas CRISPRi effects of dCas9 remained limited to the vicinity of its binding site. Single-molecule microscopy uncovered the localization dynamics of crRNP complexes. The tracks of fluorescently labeled crRNPs co-localized with regions of increased plasmid replication, supporting efficient plasmid targeting. These results identify mechanistic principles that facilitate the application of Type IV-A1 CRISPRi for the regulation of gene expression and plasmid replication.

microbiology↗

bioRxiv2024

Vanillin flavor in e-liquids does not induce endothelial cell dysfunction: the Replica Project

BackgroundThere are challenges that require collaboration among researchers to ensure that tobacco harm reduction strategies are evidence-based. One key challenge is evaluating the safety of flavors used in electronic cigarettes (e-cigarettes). While many flavorings are approved as food additives or deemed "generally recognized as safe" (GRAS) for ingestion, this does not guarantee their safety when inhaled. In this context, the international research group Replica replicated a study conducted by Fetterman and colleagues in 2018, investigating the effects of aerosolized vanillin - one of the most popular flavors in vaping - on vascular endothelium when vaporized by an electronic cigarette. MethodsWe used Aspire Zelos 3 e-cigarette and prepared e-liquids containing propylene glycol, vegetable glycerin and vanillin. The e-liquids were vaporized under two settings - regular (1 ohm coil using wattage control mode at 14 watts) and sub-ohm (0.3 ohm coil using temperature control mode at 200 {degrees}C) - using a vaping machine, following the standardized puffing regime, ISO20768:2018. The vapor was then collected into a trapping solution to prepare aqueous extracts for the treatment of human aortic endothelial cells. We evaluated cytotoxicity, oxidative stress, nitric oxide bioavailability, and inflammation addressing some gaps reported in the original study. ResultsWe observed some harmful effects, mostly attributable to ethanol, used to dilute vanillin in the original work by Fetterman, but no harmful effects on cell viability, their ability to produce nitric oxide, or oxidative stress from vanillin. Furthermore, no pro-inflammatory effects of vanillin were observed in terms of ICAM-1 and IL-6 gene expression. ConclusionsOur results confirm the endothelial cell dysfunction observed in the original paper, but clarify that these effects are mainly attributable to ethanol and not to vaporized vanillin. These findings suggest that vanillin could be a safer flavoring agent for e-cigarette, without causing adverse effects on the cardiovascular system.

pharmacology and toxicology↗

bioRxiv2022

In Vitro Toxicity Profile of myblu™ electronic cigarette Aerosol Compared to Cigarette Smoke: the REPLICA project

During the last decade electronic cigarettes (e-cigarettes) have been studied as an alternative devices to the tobacco cigarette, but with better safety for the health of smokers, so as to create a new approach to smoking addiction, such as the "smoking harm reduction". This new approach, suggested by a part of the scientific world, aroused interest and debates in the regulatory field, involving all the major regulatory bodies and often creating divergences from nation to nation on the rules driving the production, distribution and consumption of these alternative products. Many studies have been conducted both in vitro and in vivo, to clarify the effects of the e-cigarette compared to the classic one. In this context, the Center of Excellence for the Acceleration of HArm Reduction (CoEHAR) was established within the University of Catania (Italy) and the multi-center project, created under its leadership, the REPLICA project, which aims to replicate in vitro studies originally conducted by tobacco and e-cigarette manufacturers, in order to verify the robustness and replicability of the data. In this work the REPLICA Team replicated part of the work published by Rudd and colleagues in 2020, which aims to establish the aerosol-induced cytotoxicity, mutagenesis and genotoxicity of a pod system e-cigarette aerosol compared to tobacco cigarette smoke. As in the original paper, we performed Neutral Red Test (NRU) for the evaluation of cytotoxicity, AMES test for the evaluation of mutagenesis and In Vitro Micronuclei (IVM) assay for the evaluation of genotoxicity on cells treated with cigarette smoke or e-cigarette aerosol. The results obtained showed high cytotoxicity, mutagenicity and genotoxicity induced by cigarette smoke, but slight or no cytotoxic, mutagenic and genotoxic effects induced by the e-cigarette aerosol. The data obtained support those previously presented by Rudd and colleagues, although we have highlighted some methodological flaws of their work. Overall, we can affirm that the results obtained by Rudd and colleagues have been established and our data also confirm the idea that e-cigarette aerosol is much safer and less harmful than cigarette smoking, making it a useful device in smoking harm reduction.

biochemistry↗

bioRxiv2022

Nicotine measurement on Cambridge Filter PADs: an interlaboratory comparison to evaluate exposure by different electronic devices and traditional cigarette

Inter-laboratory comparison is widely used to ensure quality control among laboratories. In in vitro toxicology studies for tobacco harm reduction (THR), exposure system performance and laboratory proficiency along with product smoke and aerosol stream are tested for variability to assess accuracy. Here we aim to test a novel inter-laboratory setup created in a new collaborative research group using identical and small footprint systems- in order to minimize variability factors and increase reproducibility. Seven independent laboratories from different geographical areas tested the aerosol and smoke stream and exposure system performance (LM1 and LM4E) using Cambridge Filter Pad (CFP) trapping techniques. We tested 1R6F reference cigarettes, two electronic cigarettes (Vype e-Pen and Vype e-Stick Maxx), and two tobacco heating products (IQOS and Glo) under the appropriate ISO and/or HCI regimes. Nicotine quantification was performed by GC-FID at the laboratory of the leading center. The performance of participant laboratories was assessed by z-score values obtained from results either in relation to the mean and standard deviation of total participants or in relation to the reference leading center. Z-Scores were satisfactory when |z| [≤] 2, questionable when 2 < |z| < 3 and, unsatisfactory when |z| [≥] 3. In the first evaluation, for all the tested devices, Z- scores values generated by dosimetry data ranged from -2 to +2. However, high intra-laboratory variability (RSD> 10%) was observed for almost all laboratories. In the second, data showed borderline and unsatisfactory exposure performances versus LAB-A. Particularly, Z-scores [≥] 3 were observed once for LAB-B (e-Stick exposure) and LAB-G (e-Pen exposure), twice for LAB-C (1R6F-ISO and e-Stick exposures) and LAB-E (e-Pen and e-Stick exposures), and three times for LAB-F (1R6F-HCI, e-Pen, and Glo exposures). This study demonstrates that nicotine dosimetry is a fundamental method for quality assurance of smoke/vapor run exposure in the early stage of an interlaboratory study, allowing the identification and possibly the resolution of gaps. Extended practice sessions on exposure runs and several rounds of nicotine dosimetry testing should be planned to keep in check overall equipment and operator performance.

pharmacology and toxicology↗

bioRxiv2021

Comparative assessment of electronic nicotine delivery systems aerosol and cigarette smoke on endothelial cell migration: the Replica Project

Cigarette smoking is associated with impairment of repair mechanisms necessary for vascular endothelium homeostasis. Reducing the exposure to smoke toxicants may result in the mitigation of the harmful effect on the endothelium and cardiovascular disease development. Previous investigations performed by the tobacco industries evaluated in vitro the effect of electronic cigarette (e-cig) compared to cigarette smoke demonstrating a significant reduction in endothelial cell migration inhibition following e-cig aerosol exposure. In the present study, we replicated one of these studies, evaluating the effects of cigarette smoke on endothelial cell migration compared to e-cig and heated tobacco products. We used a multi-center approach (ring-study) to verify the robustness and reliability of the results obtained in the replicated study. Consistently with the original study, we observed a substantial reduction of the effects of e-cig and tobacco heated products on endothelial cell migration compared to cigarette smoke. In conclusion, our study further confirms the importance of e-cig and tobacco heated products as a possible harm reduction strategy for cardiovascular diseases development in smokers. HighlightsO_LICigarette smoking is strictly related to impairment of vascular repair mechanisms C_LIO_LIReducing the exposure to toxicants in smoke, could reduce the harm to endothelium C_LIO_LIENDS showed a reduced effect on endothelial cell migration compared to cigarette C_LIO_LIThese data demonstrated the reduced toxicity of ENDS compared to cigarettes. C_LI

pharmacology and toxicology↗

bioRxiv2021

Electronic nicotine delivery systems exhibit reduced bronchial epithelial cells toxicity compared to cigarette: The Replica Project

Cigarette smoking is the leading cause of preventable deaths worldwide. Electronic Nicotine Delivery Systems (ENDS) may reduce health risks associated with chronic exposure to smoke and their potential benefits have been the matter of intense scientific debate. Here we replicated three key published studies from the Tobacco Industry on cytotoxic and inflammatory effects of cigarette smoke and ENDS aerosol in an independent multicentric study. We aimed to establish the reliability of results and the robustness of conclusions by replicating the authors experimental protocols and further validating them with different techniques. We exposed human bronchial epithelial cell (NCI-H292) to cigarette smoke and to aerosol from ENDS. All the exposure were conducted at air-liquid interface to assess cytotoxicity effects of smoke and aerosol. Moreover, we aimed to assess different inflammatory mediators release (IL-6, IL-8 and MMP-1) from cells exposed to whole smoke and to smoke without particulate matter (vapor phase). We were able to replicate the results obtained in the original studies on cytotoxicity confirming that almost 80% of the cytotoxic effect of smoke is due to the vapor phase of smoke. Moreover, our results substantiated the reduced cytotoxic effects of ENDS aerosol in respect to cigarette smoke. However, our data are significantly different from the original ones in terms of inflammatory and remodeling activity triggered by smoke. Taken all together, the data obtained independently in different laboratories clearly demonstrate the reduced toxicity of ENDS products compared to cigarettes and thus providing a valuable tool to the harm reduction strategies in smokers.

pharmacology and toxicology↗

bioRxiv2021

Screening of different cytotoxicity methods for the assessment of ENDS toxicity relative tobacco cigarettes

Electronic Nicotine Delivery Systems (ENDS), i.e., electronic cigarettes (e-cigs) and Tobacco Heating Products (THPs), are rapidly growing in popularity. The marketing of these products is regulated by specific rules in the European Union and in the US, which permit their legal sales. Nonetheless, comprehensive quality and safety requirements for regulatory purposes are still under development. Cytotoxicity studies are an important initial step in appraising the potential toxicity of ENDS. The aim of the present study was to screen a battery of different in vitro cytotoxicity methods for the assessment of toxicity induced by ENDS. We evaluated different cytotoxicity assays, including neutral red uptake (NRU), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Annexin V apoptosis, High Content Screening (HCS) assays and Real Time Cell Analysis (RTCA), to compare two e-cigs (Vype ePen 3 and Vype eStick Maxx) and two THPs (IQOS and GLO) with the 1R6F reference tobacco cigarette. Human bronchial epithelial cells (H292) were exposed to 1R6F smoke (5 puffs by HCI regime), ePen vapor (10 puffs by modified HCI regime), eStick vapor (25 puffs by CRM81 regime), IQOS vapor (7 puffs by HCI regime) and GLO vapor (8 puffs by HCI regime) at air-liquid interface. All tests showed reduced cell viability following 1R6F smoke exposure and slight or no reduction with ENDS at 24 hours compared to controls. In addition, Annexin V and RTCA exhibited a further significant reduction in cell viability following 1R6F exposure compared with other assays. Furthermore, Annexin V allowed to discriminate viable cells from those in early/late apoptosis. Finally, RTCA and HCS being time-resolved analyses allowed also to determine the kinetic dependency parameter for toxicity of smoke/vapor chemicals on cell viability. In conclusion, NRU assay may be considered a suitable test, especially when combined with a time-resolved test, for assessing the kinetic of cytotoxicity induced by these products.

pharmacology and toxicology↗

bioRxiv2020

Nicotine dosimetry and stability in Cambridge Filter PADs (CFPs) following different smoking regimen protocols and condition storage

Despite the growing numbers of studies with cigarettes and other electronic nicotine delivery products (ENDs), there is no standard covering nicotine dosimetry and its stability in various matrix. The aim of the present study was to provide a protocol to normalize nicotine concentration adsorbed in Cambridge Filter PADs (CFPs) and their storage method. Smoke/vapor generated by a reference tobacco cigarette (1R6F) and ENDs with different exposure regimes (ISO, HCI and CRM81) was collected in CFPs. For each exposure, some CFPs were analyzed at time zero, whereas the others were stored under different conditions for nicotine assessment after 30 days. Principal Component Analysis (PCA) was also performed to establish the best parameter for nicotine normalization. PCA showed the best correlation between nicotine in CFPs and TPM. Our results showed differences between products and puffing regimes, but storage of CFPs at -80{degrees}C was always effective in maintaining the nicotine content. In conclusion, this study highlights that different exposure regimens and products can affect the preservation of nicotine titer in CFPs and samples storage at -80{degrees}C may prevent the loss of nicotine. These conditions are recommended and should be adopted for Inter-laboratory comparison studies on ENDs to ensure harmonization between participating laboratories.

pharmacology and toxicology↗

bioRxiv2019

A single dose of antibody-drug conjugate cures a stage 1 model of African trypanosomiasis.

Infections of humans and livestock with African trypanosomes are treated with drugs introduced decades ago that are not always fully effective and often have severe side effects. Here, the trypanosome haptoglobin-haemoglobin receptor (HpHbR) has been exploited as a route of uptake for an antibody-drug conjugate (ADC) that is completely effective against Trypanosoma brucei in the standard mouse model of infection. Recombinant human anti-HpHbR monoclonal antibodies were isolated and shown to be internalised in a receptor-dependent manner. Antibodies were conjugated to a pyrrolobenzodiazepine (PBD) toxin and killed T. brucei in vitro at picomolar concentrations. A single therapeutic dose (0.25 mg/kg) of a HpHbR antibody-PBD conjugate completely cured a T. brucei mouse infection within 2 days with no re-emergence of infection over a subsequent time course of 77 days. These experiments provide a demonstration of how ADCs can be exploited to treat protozoal diseases that desperately require new therapeutics. Author SummaryHere we show that antibody-drug conjugates (ADCs) can be re-purposed from cancer immunotherapeutics to anti-protozoals by changing the specificity of the immunoglobulin to target a trypanosome cell surface receptor. Trypanosomes were used as a model system due to the availability of receptor null cell lines that allowed the unambiguous demonstration that ADCs targeted to a parasite surface receptor could be specifically internalised via receptor-mediated endocytosis. A single low dose of the resulting ADC was able to cure a stage 1 mouse model of trypanosome infection. We have used toxins and conjugation chemistry that are identical to anti cancer ADCs demonstrating the ability to piggy-back onto the huge research efforts and resources that are being invested in the development of such ADCs. The potential for development of ADCs against a wide range of human pathogens is vast, where only epitope binding sites need vary in order to provide selectivity. This provides a far-reaching opportunity for the rapid development of novel anti-protozoals for the targeted killing of a wide range of pathogens that cause disease worldwide, especially in developing countries.

microbiology↗