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1.
Blood Adv ; 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38776400

RESUMO

Socioeconomic status (SES) and race/ethnicity have been associated with outcomes of allogeneic hematopoietic cell transplantation (allo-HCT). Certain aspects of GVHD management such as the need for long term care, prolonged immunosuppressive treatment, and need for close follow up for complications may exacerbate disparities. Adults (≥ 18 years) reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) who underwent a first alloHCT for acute leukemia, myelodysplastic syndrome, or myeloproliferative neoplasm between 2008 - 2018 were included. Endpoints for those developing GVHD included overall survival (OS), transplant related mortality (TRM), and disease relapse. Models were adjusted for patient and transplant related variables. A two-sided p-value < 0.01 was considered significant. Among the 14,825 allo-HCT recipients, 6,259 (42.2%) and 6,675 (45.0%) patients developed aGVHD and cGVHD, respectively. In patients with aGVHD, non-Hispanic Blacks had increased TRM (HR 1.50, 95% CI 1.24-1.83, p=0.0001) and overall mortality (HR 1.31, 1.14-1.50, p=0.0002) compared with non-Hispanic Whites, an association that disappeared when severity of aGVHD was included in the model. Lower SES was associated with increased risk of disease relapse (p=0.0016) but not OS or TRM. In patients who developed cGVHD, race and ethnicity were not associated with OS, TRM and disease relapse. However, the highest quartile of annual household income (≥ $80,000) had improved OS (HR 0.77, 0.69-0.85, p<0.0001) and reduced TRM (HR 0.86, 0.67-0.87, p<0.0001) compared with lowest quartile, adjusting for race and ethnicity. Race/ethnicity and SES are associated with outcomes after GVHD. Optimizing health care resources available to low SES patients and strategies to minimize the risk of severe GVHD in non-Hispanic Blacks may improve long-term outcomes.

3.
Haematologica ; 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38721749

RESUMO

Promoting access to and excellence in hematopoietic cell transplantation (HCT) by collecting and disseminating data on global HCT activities is one of the principal activities of the Worldwide Network for Blood and Marrow Transplantation, a non-Governmental organization in working relations with the World Health Organization. HCT activities are recorded annually by member societies, national registries and individual centers including indication, donor type (allogeneic/autologous), donor match and stem cell source (bone marrow/peripheral blood stem cells/cord blood). In 2018, 1,768 HCT teams in 89 countries (six WHO regions) reported 93,105 (48,680 autologous and 44,425 allogeneic) HCT. Major indications were plasma cell disorders and lymphoma for autologous, and acute leukemias and MDS/MPN for allogeneic HCT. HCT number increased from 48,709 in 2007. Notable increases were seen for autoimmune diseases in autologous and hemoglobinopathies in allogeneic HCT. The number of allogeneic HCT more than doubled with significant changes in donor match. While HCT from HLA identical siblings has seen only limited growth, HCT from non-identical related donors showed significant increase worldwide. Strongest correlation between economic growth indicator of gross national income/capita and HCT activity/ten million population was observed for autologous HCT (r=0.79). HCT from unrelated donors showed strong correlation (r=0.68), but only moderate correlation (r=0.51) was detected from related donors. The use of HCT doubled in about a decade worldwide at different speed and with significant changes regarding donor match as a sign of improved access to HCT worldwide. Although narrowing, significant gaps remain between developing and non-developing countries.

4.
ESMO Open ; 9(5): 102995, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38636292

RESUMO

BACKGROUND: Fifteen to thirty percent of all patients with metastatic breast cancer (MBC) develop brain metastases (BCBMs). Recently, the antibody-drug conjugates (ADCs) sacituzumab govitecan (SG) and trastuzumab deruxtecan (T-DXd) have shown to be highly effective in the treatment of MBC. However, there are only limited data whether these macromolecules are also effective in patients with BCBMs. We therefore aimed to examine the efficacy of SG and T-DXd in patients with stable and active BCBMs in a multicenter real-world analysis. PATIENTS AND METHODS: Female patients with stable or active BCBMs who were treated with either SG or T-DXd at three breast centers in Germany before 30 June 2023 were included. As per local clinical praxis, chemotherapy efficacy was evaluated by whole-body computed tomography and cranial magnetic resonance imaging at baseline and at least every 3 months according to local standards. Growth dynamics of BCBMs were assessed by board-certified neuroradiologists. RESULTS: Of 26 patients, with a median of 2.5 prior therapy lines in the metastatic setting (range 2-15), 12 (43%) and 16 (57%) patients received SG and T-DXd, respectively. Out of the 12 patients who received SG, 2 (17%) were subsequently treated with T-DXd. Five out of 12 (42%) and 5 out of 16 (31%) patients treated with SG and T-DXd, respectively, had active BCBMs at treatment initiation. The intracranial disease control rate was 42% [95% confidence interval (CI) 13% to 71%] for patients treated with SG and 88% (95% CI 72% to 100%) for patients treated with T-DXd. After a median follow-up of 12.7 months, median intracranial progression-free survival was 2.7 months (95% CI 1.6-10.5 months) for SG and 11.2 months (95% CI 7.5-23.7 months) for T-DXd. CONCLUSIONS: SG and T-DXd showed promising clinical activity in both stable and active BCBMs. Further prospective clinical studies designed to investigate the efficacy of modern ADCs on active and stable BCBMs are urgently needed.


Assuntos
Anticorpos Monoclonais Humanizados , Neoplasias Encefálicas , Neoplasias da Mama , Camptotecina , Imunoconjugados , Trastuzumab , Humanos , Feminino , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Neoplasias Encefálicas/secundário , Neoplasias Encefálicas/tratamento farmacológico , Anticorpos Monoclonais Humanizados/uso terapêutico , Anticorpos Monoclonais Humanizados/farmacologia , Pessoa de Meia-Idade , Trastuzumab/uso terapêutico , Trastuzumab/farmacologia , Imunoconjugados/uso terapêutico , Imunoconjugados/farmacologia , Adulto , Idoso , Camptotecina/análogos & derivados , Camptotecina/uso terapêutico , Camptotecina/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Estudos Retrospectivos
5.
Artigo em Inglês | MEDLINE | ID: mdl-38632889

RESUMO

BACKGROUND: In May 2020, news outlets reported misinformation about the Centers for Disease Control (CDC) related to COVID-19. Correcting misinformation about outbreaks and politics is particularly challenging. Affective belief echoes continue to influence audiences even after successful correction. Narrative and emotional flow scholarship suggest that a narrative corrective with a positive ending could reduce belief echoes. Therefore, this study investigated the efficacy of a narrative corrective with a relief ending for correcting misinformation about the CDC. METHODS: Between 29 May and 4 June 2020, we tested the effectiveness of a narrative to correct this misinformation. Participants in the United States (N = 469) were enrolled via Qualtrics panels in an online message experiment and randomized to receive a narrative corrective, a didactic corrective or no corrective. RESULTS: The narrative corrective resulted in lower endorsement of the misinformation compared with the control and the didactic corrective. The narrative corrective had a positive indirect effect on perceived CDC competence and mask wearing intentions for politically moderate and conservative participants via relief. CONCLUSIONS: Public health institutions, such as the CDC, should consider utilizing narrative messaging with positive emotion endings to correct misinformation. Narratives better address affective belief echoes, particularly for counter-attitudinal audiences.

6.
JCI Insight ; 9(9)2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38564292

RESUMO

Central for wound healing is the formation of granulation tissue, which largely consists of collagen and whose importance stretches past wound healing, including being implicated in both fibrosis and skin aging. Cyclophilin D (CyD) is a mitochondrial protein that regulates the permeability transition pore, known for its role in apoptosis and ischemia-reperfusion. To date, the role of CyD in human wound healing and collagen generation has been largely unexplored. Here, we show that CyD was upregulated in normal wounds and venous ulcers, likely adaptive as CyD inhibition impaired reepithelialization, granulation tissue formation, and wound closure in both human and pig models. Overexpression of CyD increased keratinocyte migration and fibroblast proliferation, while its inhibition reduced migration. Independent of wound healing, CyD inhibition in fibroblasts reduced collagen secretion and caused endoplasmic reticulum collagen accumulation, while its overexpression increased collagen secretion. This was confirmed in a Ppif-KO mouse model, which showed a reduction in skin collagen. Overall, this study revealed previously unreported roles of CyD in skin, with implications for wound healing and beyond.


Assuntos
Colágeno , Fibroblastos , Camundongos Knockout , Peptidil-Prolil Isomerase F , Pele , Cicatrização , Animais , Feminino , Humanos , Masculino , Camundongos , Movimento Celular , Proliferação de Células , Colágeno/metabolismo , Ciclofilinas/metabolismo , Ciclofilinas/genética , Modelos Animais de Doenças , Fibroblastos/metabolismo , Tecido de Granulação/metabolismo , Tecido de Granulação/patologia , Queratinócitos/metabolismo , Peptidil-Prolil Isomerase F/metabolismo , Peptidil-Prolil Isomerase F/genética , Pele/metabolismo , Pele/patologia , Suínos , Cicatrização/fisiologia
7.
Contemp Clin Trials ; 140: 107494, 2024 05.
Artigo em Inglês | MEDLINE | ID: mdl-38458557

RESUMO

BACKGROUND: Adolescents infrequently use sun protection and engage in intentional tanning more frequently compared to other age groups, leading to increased ultraviolet radiation (UVR) exposure that heightens skin cancer risk across the lifespan. High schools are therefore an ideal setting for offering skin cancer preventive interventions. Yet, there are limited UVR protection interventions for high school students, especially those that are personalized, tested using randomized designs, and include long-term outcome assessment to determine the durability of intervention effects. METHOD: The Sun-safe Habits Intervention and Education (SHINE) cluster-randomized trial will test a novel, personalized intervention that targets high school adolescents' sun protection and tanning behaviors, and tracks their outcomes for up to one year following intervention. Enrolled high schools will be randomized to receive either the personalized SHINE intervention, which includes facial UVR photographs and sun protection action planning, or standard education using publicly available materials. Students in both conditions will receive information about skin cancer, sun protection, and skin self-examination. Outcome variables will include students' sun protection and tanning behaviors and sunburn occurrence. Potential moderators (e.g., race/ethnicity) and mediators (e.g., self-efficacy) will also be assessed and tested. CONCLUSIONS: This trial examines the efficacy of a personalized intervention targeting sun protection and tanning of high school students. The project will lead to new scientific understanding of the theoretical mechanisms underlying outcomes and moderators of the intervention effects, which will inform future intervention tailoring to meet the needs of vulnerable subgroups.


Assuntos
Neoplasias Cutâneas , Queimadura Solar , Humanos , Adolescente , Neoplasias Cutâneas/prevenção & controle , Queimadura Solar/prevenção & controle , Feminino , Protetores Solares/uso terapêutico , Protetores Solares/administração & dosagem , Masculino , Educação em Saúde/organização & administração , Educação em Saúde/métodos , Raios Ultravioleta/efeitos adversos , Banho de Sol , Serviços de Saúde Escolar/organização & administração , Comportamentos Relacionados com a Saúde , Autoexame/métodos
8.
Sci Rep ; 14(1): 7109, 2024 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-38531956

RESUMO

Darier disease (DD) is a rare monogenetic skin disorder with limited data on its potential association with neurological disorders. This study aimed to investigate the association between DD and neurological disorders, specifically Parkinson's disease, dementias, and epilepsy. Using Swedish national registers in a period spanning between 1977 and 2013, 935 individuals with DD were compared with up to 100 comparison individuals each, randomly selected from the general population based on birth year, sex, and county of residence at the time of the first diagnosis of DD. Individuals with DD had increased risks of being diagnosed with Parkinson's disease (RR 2.1, CI 1.1; 4.4), vascular dementia (RR 2.1, CI 1.0; 4.2), and epilepsy, (RR 2.5, CI 1.8; 3.5). No association of DD with other dementias were detected. This study demonstrates a new association between DD and neurodegenerative disorders and epilepsy, underlining the need for increased awareness, interdisciplinary collaboration, and further research to understand the underlying mechanisms. Early identification and management of neurological complications in DD patients could improve treatment strategies and patient outcomes. The findings also highlight the role of SERCA2 in the pathophysiology of neurological disorders, offering new targets for future research and potentials for novel treatments.


Assuntos
Doença de Darier , Demência , Epilepsia , Doença de Parkinson , Humanos , Doença de Parkinson/epidemiologia , Pele , Demência/epidemiologia
9.
Health Commun ; : 1-10, 2024 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-38281912

RESUMO

The theory of normative social behavior (TNSB) postulates that people are influenced by others' behaviors, which they observe from messages and experience. In addition to focusing on perceived (i.e., descriptive and injunctive) norms, the TNSB was expanded to include collective norms, which represent what people actually do. Testing this expanded theoretical model, the current study examined whether two types of collective norms - collective political norms and collective regional norms - interacted with descriptive norms to influence pandemic mask wearing behavior expectations among U.S. adults (N = 444). The interaction was statistically significant for collective political norms (ß = -.74, p = .009) but not collective regional norms (ß = -.16, p = .85). Specifically, descriptive norms were related to increased mask wearing expectation for all values of political party collective norms, but the effects were stronger when political party collective norms were low (i.e., low mask wearing behavior was normative). The findings support the inclusion of collective norms in the TNSB, clarify the relationships among different types of norms, and provide insights for norms-based interventions.

10.
Health Commun ; 39(2): 283-296, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36683347

RESUMO

During the COVID-19 pandemic, journalists were encouraged to convey uncertainty surrounding preliminary scientific evidence, including mentioning when research is unpublished or unverified by peer review. To understand how public audiences interpret this information, we conducted a mixed method study with U.S. adults. Participants read a news article about preprint COVID-19 vaccine research in early April 2021, just as the vaccine was becoming widely available to the U.S. public. We modified the article to test two ways of conveying uncertainty (hedging of scientific claims and mention of preprint status) in a 2 × 2 between-participants factorial design. To complement this, we collected open-ended data to assess participants' understanding of the concept of a scientific preprint. In all, participants who read hedged (vs. unhedged) versions of the article reported less favorable vaccine attitudes and intentions and found the scientists and news reporting less trustworthy. These effects were moderated by participants' epistemic beliefs and their preference for information about scientific uncertainty. However, there was no impact of describing the study as a preprint, and participants' qualitative responses indicated a limited understanding of the concept. We discuss implications of these findings for communicating initial scientific evidence to the public and we outline important next steps for research and theory-building.


Assuntos
COVID-19 , Vacinas , Adulto , Humanos , COVID-19/epidemiologia , Vacinas contra COVID-19 , Incerteza , Pandemias/prevenção & controle
12.
Int J Mol Sci ; 24(23)2023 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-38069276

RESUMO

The mucus layer covering the skin of fish has several roles, including protection against pathogens and mechanical damage in which proteins play a key role. While proteins in the skin mucus layer of various common bony fish species have been explored, the proteins of shark skin mucus remain unexplored. In this pilot study, we examine the protein composition of the skin mucus in spiny dogfish sharks and chain catsharks through mass spectrometry (NanoLC-MS/MS). Overall, we identified 206 and 72 proteins in spiny dogfish (Squalus acanthias) and chain catsharks (Scyliorhinus retifer), respectively. Categorization showed that the proteins belonged to diverse biological processes and that most proteins were cellular albeit a significant minority were secreted, indicative of mucosal immune roles. The secreted proteins are reviewed in detail with emphasis on their immune potentials. Moreover, STRING protein-protein association network analysis showed that proteins of closely related shark species were more similar as compared to a more distantly related shark and a bony fish, although there were also significant overlaps. This study contributes to the growing field of molecular shark studies and provides a foundation for further research into the functional roles and potential human biomedical implications of shark skin mucus proteins.


Assuntos
Tubarões , Squalus acanthias , Animais , Projetos Piloto , Squalus acanthias/metabolismo , Espectrometria de Massas em Tandem
13.
Risk Anal ; 2023 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-37963681

RESUMO

The World Health Organization (WHO) officially declared COVID-19 a pandemic on March 11, 2020. It was a time of significant uncertainty as experts were not yet certain whether social distancing behaviors were necessary to slow the spread of the virus. Some public communicators opted to acknowledge uncertainty based on the limited evidence, whereas others downplayed uncertainty. This situation provided researchers with an opportunity to advance theory by explicating and testing cognitive responses to message uncertainty. Immediately following the WHO declaration (March 13-19, 2020), U.S. adults (N = 1186) were randomly assigned to one of six conditions in a 2 (message uncertainty: low, high) × 3 (argument support: expert, threat, precedent) between-participants experiment. Overall, perceived uncertainty negatively mediated the impact of message uncertainty on intentions. However, participant education was a key moderator. For those with more than a high school education, uncertain messages were related to higher intentions to social distance through increased critical reflection. For those with a high school education or less, uncertain messages were related to lower intentions through decreased message credibility.

14.
Acta Derm Venereol ; 103: adv10436, 2023 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-38014829

RESUMO

Hailey-Hailey disease is a rare hereditary skin disease caused by mutations in the ATP2C1 gene encoding the secretory pathway Ca2+/Mn2+-ATPase 1 (SPCA1) protein. Extracutaneous manifestations of Hailey-Hailey disease are plausible but still largely unknown. The aim of this study was to explore the association between Hailey-Hailey disease and diabetes. A population-based cohort study of 347 individuals with Hailey-Hailey  disease was performed to assess the risks of type 1  diabetes and type 2 diabetes, using Swedish nationwide registries. Pedigrees from 2 Swedish families with Hailey-Hailey disease were also investigated: 1 with concurrent type 1 diabetes and HLA-DQ3, the other with type 2 diabetes. Lastly, a clinical cohort with 23 individuals with Hailey-Hailey disease and matched healthy controls was evaluated regarding diabetes. In the register data males with Hailey-Hailey disease had a 70% elevated risk of type 2 diabetes, whereas no  excess risk among women could be confirmed. In both pedigrees an unusually high inheritance for diabetes was observed. In the clinical cohort, individuals with Hailey-Hailey disease displayed a metabolic phenotype indicative of type 2 diabetes. Hailey-Hailey disease seems to act as a synergistic risk factor for diabetes. This study indicates, for the first time, an association between Hailey-Hailey disease and diabetes and represents human evidence that SPCA1 and the Golgi apparatus may be implicated in diabetes pathophysiology.


Assuntos
Diabetes Mellitus Tipo 2 , Pênfigo Familiar Benigno , Masculino , Humanos , Feminino , Pênfigo Familiar Benigno/diagnóstico , Pênfigo Familiar Benigno/epidemiologia , Pênfigo Familiar Benigno/genética , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/genética , Linhagem , Estudos de Coortes , ATPases Transportadoras de Cálcio/genética , ATPases Transportadoras de Cálcio/metabolismo , Mutação
15.
Int J Mol Sci ; 24(18)2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37762632

RESUMO

The mucus layer covering the skin of fish has several roles, including protection against pathogens and mechanical damage. While the mucus layers of various bony fish species have been investigated, the composition and glycan profiles of shark skin mucus remain relatively unexplored. In this pilot study, we aimed to explore the structure and composition of shark skin mucus through histological analysis and glycan profiling. Histological examination of skin samples from Atlantic spiny dogfish (Squalus acanthias) sharks and chain catsharks (Scyliorhinus retifer) revealed distinct mucin-producing cells and a mucus layer, indicating the presence of a functional mucus layer similar to bony fish mucus albeit thinner. Glycan profiling using liquid chromatography-electrospray ionization tandem mass spectrometry unveiled a diverse repertoire of mostly O-glycans in the mucus of the two sharks as well as little skate (Leucoraja erinacea). Elasmobranch glycans differ significantly from bony fish, especially in being more sulfated, and some bear resemblance to human glycans, such as gastric mucin O-glycans and H blood group-type glycans. This study contributes to the concept of shark skin having unique properties and provides a foundation for further research into the functional roles and potential biomedical implications of shark skin mucus glycans.

16.
Front Cell Dev Biol ; 11: 1252318, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37771375

RESUMO

Mitochondria are intracellular organelles that play a critical role in numerous cellular processes including the regulation of metabolism, cellular stress response, and cell fate. Mitochondria themselves are subject to well-orchestrated regulation in order to maintain organelle and cellular homeostasis. Wound healing is a multifactorial process that involves the stringent regulation of several cell types and cellular processes. In the event of dysregulated wound healing, hard-to-heal chronic wounds form and can place a significant burden on healthcare systems. Importantly, treatment options remain limited owing to the multifactorial nature of chronic wound pathogenesis. One area that has received more attention in recent years is the role of mitochondria in wound healing. With regards to this, current literature has demonstrated an important role for mitochondria in several areas of wound healing and chronic wound pathogenesis including metabolism, apoptosis, and redox signalling. Additionally, the influence of mitochondrial dynamics and mitophagy has also been investigated. However, few studies have utilised patient tissue when studying mitochondria in wound healing, instead using various animal models. In this review we dissect the current knowledge of the role of mitochondria in wound healing and discuss how future research can potentially aid in the progression of wound healing research.

17.
J Health Commun ; 28(11): 728-738, 2023 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-37768095

RESUMO

When advocating for a behavior, persuasive messaging typically focuses on the context that behavior is performed in, such as mask-wearing during the COVID-19 pandemic. However, situating the advocated behavior in a different context, termed an incongruent context appeal, may persuade by increasing attention, novelty, and memorability. The current study tested this supposition in a message experiment. Participants (N = 324) were randomized to view an incongruent context (e.g. skiing) or a congruent context (i.e. COVID-19) appeal advocating for mask wearing. The incongruence appeal had a direct, positive effect on mask wearing intentions and indirect, positive effects via two serial mediation pathways: time spent with the message increased attention through novelty and memorability. Findings suggest that an incongruent context appeal is an effective strategy for persuading audiences in information-saturated environments like the COVID-19 pandemic.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Máscaras , Pandemias/prevenção & controle , COVID-19/epidemiologia , COVID-19/prevenção & controle , Atenção
19.
Macromol Rapid Commun ; : e2300406, 2023 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-37726120

RESUMO

A series of ethylene glycol-based squaramide-containing copolymers are synthesized via a post-polymerization functionalization strategy. Conversion of polymeric amines to squaramides is found to proceed in good yields, representing a versatile method of incorporating squaramides into polymers for anion recognition. Analysis of the polymers by UV-Vis and fluorescence spectroscopy revealed that anion binding takes place similarly to that of small-molecule squaramides. The presence of a fluorescent sensing group on polymer-bound squaramides allowed for a fluorescent sensing mechanism for anions that followed a similar trend in selectivity in aqueous DMSO solution, with selectivity observed for H2 PO4 - , AcO- and SO4 2- over other common anions tested. The anion response and selectivity towards anions is similar to that of analogous small-molecule squaramides, however polymeric squaramides exhibited a greater resistance to deprotonation by more basic anions, which is attributed to the closer proximity of individual squaramides on a macromolecule. The squaramide-containing polymers exhibited good water solubility, overcoming a common problem for anion sensors which are typically not sufficiently soluble in water to function in many required applications. Despite no anion binding being observed in water, this study represents a simple and effective method of creating fully water-soluble anion receptors which may be adapted to give improved binding affinity and selectivity depending on the anion binding moiety.

20.
Phys Chem Chem Phys ; 25(36): 24819-24828, 2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37671772

RESUMO

Radiation damage in biological systems by ionizing radiation is predominantly caused by secondary processes such as charge and energy transfer leading to the breaking of bonds in DNA. Here, we study the fragmentation of cytosine (Cyt) and thymine (Thy) molecules, clusters and microhydrated derivatives induced by direct and indirect ionization initiated by extreme-ultraviolet (XUV) irradiation. Photofragmentation mass spectra and photoelectron spectra of free Cyt and Thy molecules are compared with mass and electron spectra of Cyt/Thy clusters and microhydrated Cyt/Thy molecules formed by aggregation in superfluid helium (He) nanodroplets. Penning ionization after resonant excitation of the He droplets is generally found to cause less fragmentation compared to direct photoionization and charge-transfer ionization after photoionization of the He droplets. When Cyt/Thy molecules and oligomers are complexed with water molecules, their fragmentation is efficiently suppressed. However, a similar suppression of fragmentation is observed when homogeneous Cyt/Thy clusters are formed in He nanodroplets, indicating a general trend. Penning ionization electron spectra (PIES) of Cyt/Thy are broad and nearly featureless but PIES of their microhydrated derivatives point at a sequential ionization process ending in unfragmented microsolvated Cyt/Thy cations.

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