Examining longitudinal associations between initial perceptions and experiences with electronic nicotine delivery system (ENDS) use and use patterns among adults who smoke and recently initiated ENDS.

INTRODUCTION: Limited data exist on factors associated with concurrent use patterns of electronic nicotine delivery systems (ENDS) and cigarettes. We examined longitudinally perceptions and experiences with ENDS in relationship to concurrent use patterns among established, recent smokers who recently initiated ENDS. METHODS: Participant recruitment took place using paid digital advertisements on social media. Between December 2020 and October 2021, 303 adults aged ≥21 years from across the US who currently or recently smoked and had initiated ENDS use within the past 30 days or reinitiated ENDS use after more than one year of non-use were surveyed. Multinomial logistic regressions were conducted to analyze association between the outcome of current use pattern at follow-up at 1 month [rejectors (discontinued ENDS, continued smoking), primary smokers (concurrent users, mostly smoke), dual user (similar smoking and ENDS use), primary vapers (concurrent users, mostly vape), and switchers (discontinued smoking, continued using ENDS) or quitters (discontinued both smoking and ENDS] and perceptions of and experiences with ENDS predictors at baseline. RESULTS: At follow-up at 1 to 2 months after initiating ENDS, 20% were rejectors, 31% were primary smokers, 13% were dual users, 19% were primary vapers, and 17% were switchers/quitters. Perceiving ENDS as less harmful than smoking or being uncertain and as equally or more enjoyable smoking, experiencing a lot or complete reduction in cravings to smoking and in irritability with ENDS use, liking the taste of ENDS, and being satisfied with vaping were associated with higher odds of quitting smoking compared to rejecting ENDS or mostly smoking at follow-up at 1 month. CONCLUSIONS: Findings highlight the importance of initial ENDS perceptions and experiences when examining tobacco outcomes and potentially for developing policies and interventions targeting smoking cessation. ENDS initiators are differentiating into distinct use patterns based on these factors within a short period of time.

Efficacy of Lemon Myrtle Essential Oil as a Bio-Fungicide in Inhibiting Citrus Green Mould.

The effectiveness of lemon myrtle (LM) (Backhousia citriodora) essential oil (EO) was investigated to combat Penicillium digitatum by in vitro agar diffusion and vapour assay and in artificially infected oranges. The main constituent of LM EO was revealed as citral when analysed in gas chromatography-mass spectrometry. Pure citral was also included in the experiment for comparison. The in vitro fungal growth was significantly inhibited by LM EO at 1, 2, 3, 4 and 5 µL per disc while complete growth inhibition by both the pure citral and LM EO occurred at 4 and 5 µL per disc. Inoculated fruits treated by dipping in 1000 µL L-1 LM EO solutions for 5, 10, 15, 30 and 120 s showed significantly lower fungal wounds compared to control. While longer dipping times led to some rind injuries, fruits with a 5 and 10 s dip were found free from any injury. The evaluation after dipping and storage confirmed that the fruits maintained the sensory attributes and were not compromised by the incorporation of the essential oil. The results of this study indicate that LM EO can be a promising alternative to synthetic fungicides for preserving the quality of citrus fruits during storage.

Acetyl-Click Screening Platform Identifies Small-Molecule Inhibitors of Histone Acetyltransferase 1 (HAT1).

HAT1 is a central regulator of chromatin synthesis that acetylates nascent histone H4. To ascertain whether targeting HAT1 is a viable anticancer treatment strategy, we sought to identify small-molecule inhibitors of HAT1 by developing a high-throughput HAT1 acetyl-click assay. Screening of small-molecule libraries led to the discovery of multiple riboflavin analogs that inhibited HAT1 enzymatic activity. Compounds were refined by synthesis and testing of over 70 analogs, which yielded structure-activity relationships. The isoalloxazine core was required for enzymatic inhibition, whereas modifications of the ribityl side chain improved enzymatic potency and cellular growth suppression. One compound (JG-2016 [24a]) showed relative specificity toward HAT1 compared to other acetyltransferases, suppressed the growth of human cancer cell lines, impaired enzymatic activity in cellulo, and interfered with tumor growth. This is the first report of a small-molecule inhibitor of the HAT1 enzyme complex and represents a step toward targeting this pathway for cancer therapy.

Structural and functional characterization of NEMO cleavage by SARS-CoV-2 3CLpro.

In addition to its essential role in viral polyprotein processing, the SARS-CoV-2 3C-like protease (3CLpro) can cleave human immune signaling proteins, like NF-κB Essential Modulator (NEMO) and deregulate the host immune response. Here, in vitro assays show that SARS-CoV-2 3CLpro cleaves NEMO with fine-tuned efficiency. Analysis of the 2.50 Å resolution crystal structure of 3CLpro C145S bound to NEMO226-234 reveals subsites that tolerate a range of viral and host substrates through main chain hydrogen bonds while also enforcing specificity using side chain hydrogen bonds and hydrophobic contacts. Machine learning- and physics-based computational methods predict that variation in key binding residues of 3CLpro-NEMO helps explain the high fitness of SARS-CoV-2 in humans. We posit that cleavage of NEMO is an important piece of information to be accounted for, in the pathology of COVID-19.

Mindfulness-Based Smoking Cessation Delivered Through Telehealth and Text Messaging for Low-Income Smokers: Protocol for a Randomized Controlled Trial.

BACKGROUND: Tobacco use is the leading cause of preventable morbidity and mortality. Adults with low income and members of certain racial and ethnic minority groups are less likely to quit, and therefore, they experience profound tobacco-related health disparities. Mindfulness training can increase the rates of smoking cessation and lapse recovery, and telehealth and SMS text messaging have the potential to provide more accessible treatment. OBJECTIVE: This study aims to test the efficacy of delivering mindfulness-based smoking cessation treatment through text messaging (iQuit Mindfully) and telehealth (group videoconferencing), both as stand-alone interventions and in combination. In addition, it aims to examine the underlying mechanisms of mindfulness treatment. METHODS: In this 2×2 randomized controlled trial, participants are randomized into 1 of 4 groups based on assignment to iQuit Mindfully text messages (yes or no) and mindfulness videoconference groups (yes or no). The primary outcomes are biochemically verified smoking abstinence at 8, 12, and 24 weeks after the start of treatment. Secondary outcomes include the frequency of home mindfulness practice and self-reported levels of mindfulness, emotions, craving, withdrawal, dependence, self-efficacy, and social support. RESULTS: Recruitment, treatment, and assessment began in spring and summer 2021, and data collection is expected to continue through spring 2024. CONCLUSIONS: This project aims to improve smoking cessation outcomes for low-income, racially and ethnically diverse smokers through mindfulness-based telehealth group counseling and text messaging support. We also aim to advance the scientific study of the mechanisms of action of mindfulness treatment, which could inform the development of more efficacious and efficient treatments to reduce tobacco disparities. TRIAL REGISTRATION: Clinicaltrials.gov NCT04965181; https://clinicaltrials.gov/ct2/show/NCT04965181. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/35688.

Structural and functional characterization of NEMO cleavage by SARS-CoV-2 3CLpro.

In addition to its essential role in viral polyprotein processing, the SARS-CoV-2 3C-like (3CLpro) protease can cleave human immune signaling proteins, like NF-κB Essential Modulator (NEMO) and deregulate the host immune response. Here, in vitro assays show that SARS-CoV-2 3CLpro cleaves NEMO with fine-tuned efficiency. Analysis of the 2.14 Å resolution crystal structure of 3CLpro C145S bound to NEMO 226-235 reveals subsites that tolerate a range of viral and host substrates through main chain hydrogen bonds while also enforcing specificity using side chain hydrogen bonds and hydrophobic contacts. Machine learning- and physics-based computational methods predict that variation in key binding residues of 3CLpro- NEMO helps explain the high fitness of SARS-CoV-2 in humans. We posit that cleavage of NEMO is an important piece of information to be accounted for in the pathology of COVID-19.

Cost-Effectiveness of Population-Based Tobacco Control Interventions on the Health Burden of Cardiovascular Diseases in Vietnam.

This study sought to assess the cost-effectiveness of population-based tobacco control interventions, which included health promotion and education, smoke-free models, cessation programs, warning on package, marketing bans, and raising tax. Standardized activity-based costing ingredient approach was applied with the provider perspective to calculate interventions cost from 2013 to 2017. The potential health impacts of the aforementioned interventions were calculated through a Microsoft Excel-based modeling adapted from Higashi et al and Ngalesoni et al. All six population-based tobacco control interventions were highly cost-effective with ranges from 1405 VND (Vietnamese Dong) to 135 560 VND per DALY (disability-adjusted life year) averted. It was identified that raising cigarette taxes and applying health warnings on tobacco packages are the most favorable, cost-effective interventions. The results from this study provide a robust message that calls for increased attention and efforts in developing an appropriate policy agenda, which jointly integrates both political and community-based interventions, to maximize intervention impact on tobacco use.

Transcriptional Factors of Thermogenic Adipocyte Development and Generation of Brown and Beige Adipocytes From Stem Cells.

Brown and beige adipocytes have been widely known for their potential to dissipate excessive energy into heat form, resulting in an alleviation of obesity and other overweight-related conditions. This review highlights the origins, characteristics, and functions of the various kinds of adipocytes, as well as their anatomic distribution inside the human body. This review mainly focuses on various essential transcriptional factors such as PRDM16, FGF21, PPARα, PPARγ and PGC-1α, which exert their effects on the development and activation of thermogenic adipocytes via important pathways such as JAK-STAT, cAMP-PKA and PI3K-AKT signaling pathways. Additionally, this review will underline promising strategies to generate an unexhausted source of thermogenic adipocytes differentiated from human stem cells. These exogenous thermogenic adipocytes offer therapeutic potential for improvement of metabolic disorders via application as single cell or whole tissue transplantation. Graphical abstract Caption is required. Please provide.

Perceptions About Mindfulness and Text Messaging for Smoking Cessation in Vietnam: Results From a Qualitative Study.

BACKGROUND: With 15.6 million smokers, Vietnam is one of the top 10 largest cigarette-consuming countries in the world. Unfortunately, smoking cessation programs are still scarce in Vietnam. Mindfulness-based and text messaging-based interventions have been increasingly used in smoking cessation studies in developed countries, with promising results. Given the exponential growth of mobile phone usage in Vietnam in recent years, mobile health interventions could be a potential strategy to increase smoking cessation in Vietnam. However, substantial cultural adaptations are needed to optimize the effectiveness of these interventions among Vietnamese smokers. OBJECTIVE: This study aims to involve qualitative research to inform the development of a mindfulness-based text messaging smoking cessation intervention for Vietnamese smokers. METHODS: A total of 10 focus groups were conducted with 71 Vietnamese male smokers aged between 18 and 65 years (5-9 participants per focus group). Overall, 5 focus groups were conducted with smokers who had the intention to quit (ie, preparation stage of change in the transtheoretical model), and 5 focus groups were conducted with smokers who did not have the intention to quit (contemplation or precontemplation stage). The focus groups were audio recorded, transcribed verbatim, and analyzed using NVivo 12 software (QSR International). RESULTS: The major themes included smoking triggers, barriers and facilitators for quitting, the perceptions of text messaging and mindfulness approaches for smoking cessation, and suggestions for the development of a text messaging-based smoking cessation program. Common smoking triggers included stress, difficulties concentrating, and fatigue. Frequently encountering other people who were smoking was a common barrier to quitting. However, participants indicated that concerns about the harmful effects of smoking on themselves and their wives and children, and encouragement from family members could motivate them to quit. The participants preferred diverse message content, including information about the consequences of smoking, encouragement to quit, and tips to cope with cravings. They suggested that text messages be clear and concise and use familiar language. Most smokers perceived that mindfulness training could be useful for smoking cessation. However, some suggested that videos or in-person training may also be needed to supplement teaching mindfulness through text messages. CONCLUSIONS: This study provides important insights to inform the development of a text messaging-based smoking cessation program that incorporates mindfulness for Vietnamese male smokers. The results could also be useful for informing similar programs in other low- and middle-income countries.

Protein Molecular Dynamics Simulations with Approximate QM: What Can We Learn?

Classical force fields are essential for computer simulations of proteins and are typically parameterized to reproduce secondary and tertiary structure of isolated proteins. However, while protein-protein interactions are ubiquitous in nature, they are not considered in parameterization efforts and are far less understood than isolated proteins. A better characterization of intermolecular interactions is widely recognized as a key to revolutionizing drug and therapeutic developments with high-throughput computational screening. Urgently needed is a critical assessment of the performance of modern protein force fields against first-principles electronic structure methods and experiments. In a daring step toward this goal, we here describe a comparison of peptide folding dynamics as predicted by a molecular mechanics force field on the one hand and by an approximate electronic structure quantum mechanical (QM) method based on density-functional tight-binding (DFTB) on the other. We further compare the dynamics from straightforward DFTB simulations with a near-linear scaling version of DFTB for massively parallel computation based on the fragment molecular orbital (FMO-DFTB) method. We illustrate differences between the phenomenology of the folding dynamics from these three methods for a small model peptide, as well as charge polarization and dynamic fluctuations, point out possible correlations and implications for force field developers, and discuss the lessons learned that might become applicable to future predictive high-throughput computer screening for personalized neoantigen cancer therapy.

Willingness to use and pay for smoking cessation service via text-messaging among Vietnamese adult smokers, 2017.

OBJECTIVES: To examine willingness to use (WTU) and willingness to pay (WTP) for smoking cessation service via text-messaging among adult smokers in Vietnam in 2017; and to identify demographic and socioeconomic factors associated with the WTU and WTP. METHODS: A cross-sectional study of 602 adult smokers who had intention to quit in the next 12 months was conducted in Vietnam in 2017. Participants were provided with the information about a mobile health (mHealth) smoking cessation service via text-messaging and asked about their willingness to use and pay for it. The contigent valuation method was used to estimate the WTP for the service, using single bound question format. Discrete choice model was applied to estimate the average WTP and its associated factors. RESULTS: Seventy-two percent of smokers expressed willingness to use smoking cessation service via text-messaging if it were available. The average willingness to pay among those interested in using the mHealth cessation service was 82,000 VND (US$3.5). Smoking status and quit attempts in the last twelve months were associated with WTU, whereas age of the smokers and monthly income were significant predictors of WTP. CONCLUSION: A high proportion of Vietnamese smokers with intention to quit were interested in using smoking cessation services via text-messaging. The high level of smokers' willingness to use and pay for the text messaging cessation program indicates the mHealth methods could be a potential option for developing and delivering smoking cessation services in Vietnam.

The Fragment Molecular Orbital Method Based on Long-Range Corrected Density-Functional Tight-Binding.

The presently available linear scaling approaches to density-functional tight-binding (DFTB) based on the fragment molecular orbital (FMO) method are severely impacted by the problem of artificial charge transfer due to the self-interaction error (SIE), which hampers the simulation of zwitterionic systems such as biopolymers or ionic liquids. Here we report an extension of FMO-DFTB where we included a long-range corrected (LC) functional designed to mitigate the DFTB SIE, called the FMO-LC-DFTB method, resulting in a robust method which succeeds in simulating zwitterionic systems. Both energy and analytic gradient are developed for the gas phase and the polarizable continuum model of solvation. The scaling of FMO-LC-DFTB with system size N is shown to be almost linear, O( N1.13-1.28), and its numerical accuracy is established for a variety of representative systems including neutral and charged polypeptides. It is shown that pair interaction energies between fragments for two mini-proteins are in excellent agreement with results from long-range corrected density functional theory. The new method was employed in long time scale (1 ns) molecular dynamics simulations of the tryptophan cage protein (PDB: 1L2Y ) in the gas phase for four different protonation states and in stochastic global minimum structure searches for 1-ethyl-3-methylimidazolium nitrate ionic liquid clusters containing up to 2300 atoms.

Polyphenol-rich foods and risk of gestational diabetes: a systematic review and meta-analysis.

Animal studies have demonstrated anti-diabetic properties of several food-derived polyphenols, but data in humans remains unclear. This study aimed to review and meta-analyse evidence concerning the effect of the intake of several polyphenol-rich foods on gestational diabetes (GDM) risk. A systematic literature search was conducted in PubMed, Web of Science and Embase databases for observational studies on the association between dietary intake of foods/diets rich in polyphenols and GDM risk. Inclusion criteria were original research articles with full texts published in peer-reviewed English language journals, which investigated foods within the top 100 richest dietary sources of polyphenols and reported odds ratio/relative risk with their corresponding 95% confidence intervals. The quality of included studies was assessed using the Newcastle-Ottawa Scale. The intake of polyphenol-rich foods and dietary patterns in relation to GDM were pooled with fixed- and random-effects models. In total, 12 (10 cohort, 1 cross-sectional and 1 case-control) studies were included for the final systematic review, comprising 124,959 participants and including 5,786 women with GDM. Five studies found a significant, inverse association between the intake of polyphenol-rich foods or Mediterranean diet and GDM, whereas five studies reported no association and two exhibited a positive association. Meta-analyses further showed that the risk of GDM was about halved amongst women with the highest score of Mediterranean diet compared to those with the lowest score. The results suggest that dietary patterns rich in polyphenols may reduce the risk of GDM despite inconclusive evidence for polyphenol-rich food groups.

The novel microtubule targeting agent BAL101553 in combination with radiotherapy in treatment-refractory tumor models.

BACKGROUND AND PURPOSE: Resistance to microtubule targeting agents (MTA) represents a major drawback in successful cancer therapy with MTAs. Here we investigated the combined treatment modality of the novel MTA BAL101553 in combination with radiotherapy in paclitaxel and epothilone-resistant tumor models. MATERIAL AND METHODS: Multiple regimens of BAL101553, or its active moiety BAL27862 for in vitro experiments, were probed in combination with radiotherapy in P-glycoprotein-overexpressing, human colon adenocarcinoma cells (SW480) and in tubulin-mutated human NSCLC cells (A549EpoB40) and tumors thereof. RESULTS: BAL27862 reduced the proliferative activity of SW480 and A549EpoB40 tumor cells with similar potency as in A549 wildtype cells. Combined treatment of BAL27862 with ionizing radiation in vitro resulted in an additive reduction of clonogenicity. Moreover, treatment of paclitaxel- and epothilone-resistant tumors with fractionated irradiation and different regimens of BAL101553 (a single i.v. bolus vs. oral daily) suppressed tumor growth and resulted in an extended additive tumor growth delay with strong reduction of tumor proliferation and mean tumor vessel density. CONCLUSIONS: BAL101553 is a promising alternative in taxane- and epothilone-refractory tumors as part of a combined treatment modality with ionizing radiation. Its potent antitumor effect is not only tumor cell-directed but also targets the tumor microenvironment.

Synthesis and anti-proliferative activity of novel azazerumbone conjugates with chalcones.

The conjugation of azazerumbone ((3E,7E,11E)-5,5,8,12-tetramethylazacyclododeca-3,7,11-trien-2-one (7)) and 2,4-dihydroxychalcones was carried out for the preparation of novel target compounds 9a-g with 1-ethylene-4-methylene-1,2,3-triazole linker and 10a-f with propylene linker between amide nitrogen of azazerumbone and 4-hydroxy group of chalcone. The anti-proliferative activity of these compounds against the LU-1, Hep-G2, MCF-7 and SW480 human cancer cell lines were significantly improved compared to those of azazerumbone or zerumbone. The anti-proliferative activities of (3E,7E,11E)-1-((1-(2-(3-hydroxy-4-((E)-3-(3-methoxyphenyl)acryloyl)phenoxy)ethyl)-1H-1,2,3-triazol-4-yl)methyl)-5,5,8,12-tetramethyl azacyclododeca-3,7,11-trien-2-one (9b) and (3E,7E,11E)-1-(3-(4-((E)-3-(3,4,5-trimethoxyphenyl)acryloyl)phenoxy)propyl)-5,5,8,12-tetramethylazacyclododeca-3,7,11-trien-2-one (10d) are nearly comparable to those of ellipticine.

Combined treatment strategies for microtubule stabilizing agent-resistant tumors.

BACKGROUND: Resistance to microtubule-stabilizing agents is a major hurdle for successful cancer therapy. We investigated combined treatment of microtubule-stabilizing agents (MSAs) with inhibitors of angiogenesis to overcome MSA resistance. METHODS: Treatment regimens of clinically relevant MSAs (patupilone and paclitaxel) and antiangiogenic agents (everolimus and bevacizumab) were investigated in genetically defined MSA-resistant lung (A549EpoB40) and colon adenocarcinoma (SW480) tumor xenografts in nude mice (CD1-Foxn1, ICRnu; 5-14 per group). Tumor growth delays were calculated by Kaplan-Meier analysis with Holm-Sidak tests. All statistical tests were two-sided. RESULTS: Inhibition of mTOR-kinase by everolimus only minimally reduced the proliferative activity of ß tubulin-mutated lung adenocarcinoma cells alone and in combination with the MSA patupilone, but everolimus inhibited expression and secretion of vascular endothelial growth factor (VEGF) from these cells. mTOR-kinase inhibition strongly sensitized tumor xenografts derived from these otherwise MSA-resistant tumor cells to patupilone. Tumors treated with the combined modality of everolimus and patupilone had statistically significantly reduced tumor volume and stronger tumor growth delay (16.2 ± 1.01 days) than control- (7.7 ± 0.3 days, P = .004), patupilone- (10 ± 0.97 days, P = .009), and everolimus-treated (10.6 ± 1.4 days, P = .014) tumors. A combined treatment modality with bevacizumab also resensitized this MSA-refractory tumor model to patupilone. Treatment combination also strongly reduced microvessel density, corroborating the relevance of VEGF targeting for the known antivasculature-directed potency of MSA alone in MSA-sensitive tumor models. Resensitization to MSAs was also probed in P glycoprotein-overexpressing SW480-derived tumor xenografts. Different bevacizumab regimens also sensitized this otherwise-resistant tumor model to clinically relevant MSA paclitaxel. CONCLUSIONS: A treatment combination of MSAs with antiangiogenic agents is potent to overcome tumor cell-linked MSA resistance and should be considered as strategy for MSA-refractory tumor entities.

Dynamics of tumor hypoxia in response to patupilone and ionizing radiation.

Tumor hypoxia is one of the most important parameters that determines treatment sensitivity and is mainly due to insufficient tumor angiogenesis. However, the local oxygen concentration in a tumor can also be shifted in response to different treatment modalities such as cytotoxic agents or ionizing radiation. Thus, combined treatment modalities including microtubule stabilizing agents could create an additional challenge for an effective treatment response due to treatment-induced shifts in tumor oxygenation. Tumor hypoxia was probed over a prolonged observation period in response to treatment with different cytotoxic agents, using a non-invasive bioluminescent ODD-Luc reporter system, in which part of the oxygen-dependent degradation (ODD) domain of HIF-1α is fused to luciferase. As demonstrated in vitro, this system not only detects hypoxia at an ambient oxygen concentration of 1% O(2), but also discriminates low oxygen concentrations in the range from 0.2 to 1% O(2). Treatment of A549 lung adenocarcinoma-derived tumor xenografts with the microtubule stabilizing agent patupilone resulted in a prolonged increase in tumor hypoxia, which could be used as marker for its antitumoral treatment response, while irradiation did not induce detectable changes in tumor hypoxia. Furthermore, despite patupilone-induced hypoxia, the potency of ionizing radiation (IR) was not reduced as part of a concomitant or adjuvant combined treatment modality.

Radiotherapy promotes tumor-specific effector CD8+ T cells via dendritic cell activation.

Radiotherapy is an important treatment for cancer. The main mode of action is thought to be the irreversible damage to tumor cell DNA, but there is evidence that irradiation mobilizes tumor-specific immunity, and recent studies showed that the efficacy of high-dose radiotherapy depends on the presence of CD8(+) T cells. We show in this study that the efficacy of radiotherapy given as a single, high dose (10 Gy) crucially depends on dendritic cells and CD8(+) T cells, whereas CD4(+) T cells or macrophages are dispensable. We show that local high-dose irradiation results in activation of tumor-associated dendritic cells that in turn support tumor-specific effector CD8(+) T cells, thus identifying the mechanism that underlies radiotherapy-induced mobilization of tumor-specific immunity. We propose that in the absence of irradiation, the activation status of dendritic cells rather than the amount of tumor-derived Ag is the bottleneck, which precludes efficient anti-tumor immunity.

Ionizing radiation and inhibition of angiogenesis in a spontaneous mammary carcinoma and in a syngenic heterotopic allograft tumor model: a comparative study.

BACKGROUND: The combined treatment modality of ionizing radiation (IR) with inhibitors of angiogenesis (IoA) is a promising treatment modality based on preclinical in vivo studies using heterotopic xeno- and allograft tumor models. Nevertheless reservations still exist to translate this combined treatment modality into clinical trials, and more advanced, spontaneous orthotopic tumor models are required for validation to study the efficacy and safety of this treatment modality. FINDINGS: We therefore investigated the combined treatment modality of IR in combination with the clinically relevant VEGF receptor (VEGFR) tyrosine kinase inhibitor PTK787 in the MMTV/c-neu induced mammary carcinoma model and a syngenic allograft tumor model using athymic nude mice. Mice were treated with fractionated IR, the VEGFR-inhibitor PTK787/ZK222584 (PTK787), or in combination, and efficacy and mechanistic-related endpoints were probed in both tumor models. Overall the treatment response to the IoA was comparable in both tumor models, demonstrating minimal tumor growth delay in response to PTK787 and PTK787-induced tumor hypoxia. Interestingly spontaneously growing tumors were more radiosensitive than the allograft tumors. More important combined treatment of irradiation with PTK787 resulted in a supraadditive tumor response in both tumor models with a comparable enhancement factor, namely 1.5 and 1.4 in the allograft and in the spontaneous tumor model, respectively. CONCLUSIONS: These results demonstrate that IR in combination with VEGF-receptor tyrosine kinase inhibitors is a valid, promising treatment modality, and that the treatment responses in spontaneous mammary carcinomas and syngenic allografts tumor models are comparable.