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1.
ESMO Open ; 9(4): 102991, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38631269

RESUMO

BACKGROUND: Advances in surgical techniques and systemic treatments have increased the likelihood of achieving radical surgery and long-term survival in metastatic colorectal cancer (mCRC) patients with initially unresectable colorectal liver metastases (CRLMs). Nonetheless, roughly half of the patients resected after an upfront systemic therapy experience disease relapse within 6 months from surgery, thus leading to the question whether surgery is actually beneficial for these patients. MATERIALS AND METHODS: A real-world dataset of mCRC patients with initially unresectable liver-limited disease treated with conversion chemotherapy followed by radical resection of CRLMs at three high-volume Italian institutions was retrospectively assessed with the aim of investigating the association of baseline and pre-surgical clinical, radiological and molecular factors with the risk of relapse within 6 or 12 months from surgery. RESULTS: Overall, 268 patients were included in the analysis and 207 (77%) experienced recurrence. Ninety-six (46%) of them had disease relapse within 6 months after CRLM resection and in spite of several variables associated with early recurrence at univariate analyses, only primary tumour resection at diagnosis [odds ratio (OR) 0.53, 95% confidence interval (CI) 0.32-0.89, P = 0.02] remained significant in the multivariable model. Among patients with resected primary tumours, pN+ stage was associated with higher risk of disease relapse within 6 months (OR 3.02, 95% CI 1.23-7.41, P = 0.02). One hundred and forty-nine patients (72%) had disease relapse within 12 months after CRLMs resection but none of the analysed variables was independently associated with outcome. CONCLUSIONS: Clinical, radiological and molecular factors assessed before and after conversion chemotherapy do not reliably predict early recurrence after secondary resection of initially unresectable CRLMs. While novel markers are needed to optimize the cost/efficacy balance of surgical procedures, CRLM resection should be offered as soon as metastases become resectable during first-line chemotherapy to all patients eligible for surgery.


Assuntos
Neoplasias Colorretais , Neoplasias Hepáticas , Recidiva Local de Neoplasia , Humanos , Neoplasias Colorretais/patologia , Neoplasias Colorretais/cirurgia , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/cirurgia , Neoplasias Hepáticas/tratamento farmacológico , Masculino , Feminino , Pessoa de Meia-Idade , Estudos Retrospectivos , Idoso , Hepatectomia/métodos
2.
PLoS One ; 18(6): e0287062, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37379311

RESUMO

Breast cancer is the most common cancer among women worldwide. Molecular and clinical evidence indicated that Fragile X Messenger Ribonucleoprotein 1 (FMRP) plays a role in different types of cancer, including breast cancer. FMRP is an RNA binding protein that regulates the metabolism of a large group of mRNAs coding for proteins involved in both neural processes and in epithelial-mesenchymal transition, a pivotal mechanism that in cancer is associated to tumor progression, aggressiveness and chemoresistance. Here, we carried out a retrospective case-control study of 127 patients, to study the expression of FMRP and its correlation with metastasis formation in breast cancer. Consistent with previous findings, we found that FMRP levels are high in tumor tissue. Two categories have been analyzed, tumor with no metastases (referred as control tumors, 84 patients) and tumor with distant metastatic repetition, (referred as cases, 43 patients), with a follow-up of 7 years (mean). We found that FMRP levels were lower in both the nuclei and the cytoplasm in the cases compared to control tumors. Next, within the category cases (tumor with metastases) we evaluated FMRP expression in the specific sites of metastasis revealing a nuclear staining of FMRP. In addition, FMRP expression in both the nuclear and cytoplasmic compartment was significantly lower in patients who developed brain and bone metastases and higher in hepatic and pulmonary sites. While further studies are required to explore the underlying molecular mechanisms of FMRP expression and direct or inverse correlation with the secondary metastatic site, our findings suggest that FMRP levels might be considered a prognostic factor for site-specific metastasis.


Assuntos
Neoplasias da Mama , Síndrome do Cromossomo X Frágil , Neoplasias Mamárias Animais , Animais , Humanos , Feminino , Proteína do X Frágil da Deficiência Intelectual/genética , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Estudos de Casos e Controles , Estudos Retrospectivos , Proteínas/metabolismo , Neoplasias da Mama/genética , Síndrome do Cromossomo X Frágil/genética
3.
Animals (Basel) ; 13(4)2023 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-36830515

RESUMO

The aim of this study was to assess if molasses could modify VFA production and the rumen microbial community in vitro. Three beet (treatment Beet) and three cane (treatment Cane) molasses preparations were randomly selected from a variety of samples collected worldwide and incubated in vitro with rumen fluid along with a control sample (treatment CTR, in which no molasses was used). Flasks for VFA analysis were sampled at 0, 1, 2, 3, 4, 6, 8, and 24 h of each incubation. For microbiota analysis, samples from each fermentation flask after 12 and 24 h were subjected to microbial DNA extraction and V3-V4 16S rRNA gene sequencing on an Illumina MiSeq platform. Total net VFA production was higher in the beet and cane preparations than in the control (CTR) group at 24 h (33 mmol/L, 34 mmol/L, and 24.8 mmol/L, respectively), and the composition of VFAs was affected by the inclusion of molasses: acetic acid increased in the CTR group (73.5 mol%), while propionic acid increased in the beet and cane molasses (19.6 mol% and 18.6 mol%, respectively), and butyric acid increased, especially in the cane group (23.2 mol%). Molasses even influenced the composition of the rumen microbiota, and particularly the relative abundance of the most dominant family in the rumen, Prevotellaceae, which decreased compared to CTR (37.13%, 28.88%, and 49.6%, respectively). In contrast, Streptococcaceae (19.62% and 28.10% in molasses compared to 6.23% in CTR), Veillonellaceae (6.48% and 8.67% in molasses compared to 4.54% in CTR), and Fibrobacteraceae (0.90% and 0.88% in molasses compared to 0.62% in CTR) increased in the beet and cane groups compared to the CTR group. Another important finding is the lower proportion of Methanobacteriaceae following the addition of molasses compared to CTR (0.26%, 0.28%, and 0.43%, respectively). This study showed the impact of molasses in influencing VFA production and composition as a result of a modified rumen microbial composition.

4.
Dig Liver Dis ; 55(4): 534-540, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36369195

RESUMO

BACKGROUND: Cholangiocarcinoma (CCA) is a rare biliary tract tumor with poor prognosis that often is challenging to diagnose and the majority of patients present with advanced stage. Squamous cell carcinoma antigen 1 (SCCA1) overexpression has been found in different tumors associated with poor prognosis and chemoresistance. AIMS: To assess the presence and possible prognostic role of SCCA1/2 isoforms in bile and serum of patients with CCA. METHODS: Forty seven surgical patients (36 with CCA and 11 with benign diseases) were prospectively included in the study. Serum and bile specimens were collected at the time of surgery and free and IgM-complexed SCCA was quantified by ELISA (Xeptagen, srl). RESULTS: Free or IgM linked SCCA was rarely found in serum, while SCCA was detectable in bile samples of patients with CCA, especially in those with extrahepatic form (43% vs 17%, p = 0.008), but not in controls. Despite similar tumor stage, these positive patients presented a trend toward a higher percentage of portal invasion (27% vs 15%) and of tumor recurrence than negative cases (62% vs 40%), although the difference was not statistically significant. CONCLUSION: These preliminary results indicate that bile testing for SCCA is a specific marker of extrahepatic CCA, with potential prognostic value.


Assuntos
Neoplasias dos Ductos Biliares , Colangiocarcinoma , Neoplasias Hepáticas , Humanos , Bile , Biomarcadores Tumorais , Recidiva Local de Neoplasia , Neoplasias Hepáticas/diagnóstico , Colangiocarcinoma/diagnóstico , Imunoglobulina M , Neoplasias dos Ductos Biliares/diagnóstico
5.
Eur Phys J Plus ; 136(10): 1072, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34722098

RESUMO

In early December 2019, some people in China were diagnosed with an unknown pneumonia in Wuhan, in the Hubei province. The responsible of the outbreak was identified in a novel human-infecting coronavirus which differs both from severe acute respiratory syndrome coronavirus and from Middle East respiratory syndrome coronavirus. The new coronavirus, officially named severe acute respiratory syndrome coronavirus 2 by the International Committee on Taxonomy of Viruses, has spread worldwide within few weeks. Only two vaccines have been approved by regulatory agencies and some others are under development. Moreover, effective treatments have not been yet identified or developed even if some potential molecules are under investigation. In a pandemic outbreak, when treatments are not available, the only method that contribute to reduce the virus spreading is the adoption of social distancing measures, like quarantine and isolation. With the intention of better managing emergencies like this, which are a great public health threat, it is important to dispose of predictive epidemiological tools that can help to understand both the virus spreading in terms of people infected, hospitalized, dead and recovered and the effectiveness of containment measures.

6.
Ital J Pediatr ; 47(1): 209, 2021 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-34663397

RESUMO

BACKGROUND: The social consequences of COVID-19 pandemic are universally known. In particular, the pediatric population is dealing with a radical lifestyle change. For some risk categories, such as overweight or obese children, the impact of home confinement has been greater than for others. The increased sedentary life, the wrong diet and social distancing have stopped the chance of losing weight. The aims of this study were to analyse the impact of COVID-19 lockdown on the behavior changes in a obese pediatric population and to explore the correlation between the new lifestyle and the level of parental instruction. METHODS: Data show features of 40 obese and overweight pediatric patients of our Clinic in Messina (Italy). We evaluated weight, height, BMI and other biochemical parameters: total cholesterol, HDL, LDL, triglyceride, transaminases, glycemia and insulinemia. After the lockdown, we contacted all patients in order to get some information about diet, physical activity and sedentary lifestyle changes in correlation to the level of their parents' instruction. Additionally, we also evaluated 20 children twice from a clinical and laboratory perspective. RESULTS: The study showed an increase of daily meals during COVID-19 lockdown (3.2 ± 0.4 vs 5 ± 1, P < 0.001). In particular, children whose parents have primary school diploma ate a greater significant number of meals during the lockdown, compared to those who have parents with secondary school diploma (P = 0.0019). In addition, the 95% of patients did low physical activity during the lockdown and the 97.5% spent more time in sedentary activity. Even if BMI's values don't show significant differences, they have increased after the lockdown. We didn't find any correlation between biochemical parameters before and after the lockdown. CONCLUSION: The lockdown has had bad consequences on good style of life's maintenance in overweight and obese children. The absence of a significant correlation between the worsening of biochemical parameters and the lockdown doesn't allow to exclude any long-term consequences. It's safe to assume that, if the hours spent in sedentary activity and the number of meals don't diminish, there will probably repercussion on the biochemical parameters.


Assuntos
COVID-19/epidemiologia , Controle de Doenças Transmissíveis/métodos , Exercício Físico/fisiologia , Estilo de Vida , Sobrepeso/epidemiologia , Obesidade Infantil/epidemiologia , Quarentena/métodos , Adolescente , Índice de Massa Corporal , Criança , Pré-Escolar , Comorbidade , Feminino , Humanos , Itália/epidemiologia , Masculino , Pandemias , Obesidade Infantil/fisiopatologia , Obesidade Infantil/psicologia , Estudos Retrospectivos , SARS-CoV-2
7.
Phys Chem Chem Phys ; 22(20): 11583-11592, 2020 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-32400802

RESUMO

The human telomeric G-quadruplex structural motif of DNA has come to be known as a new and stimulating target for anticancer drug discovery. Small molecules that interact with G-quadruplex structures in a selective way have gained impressive interest in recent years as they may serve as potential therapeutic agents. Here, we show how circular dichroism, UV resonance Raman and small angle X-ray scattering spectroscopies can be effectively combined to provide insights into structural and molecular aspects of the interaction between human telomeric quadruplexes and ligands. This study focuses on the ability of berberine and palmatine to bind with human telomeric quadruplexes and provides analysis of the conformational landscape visited by the relevant complexes upon thermal unfolding. With increasing temperature, both free and bound G-quadruplexes undergo melting through a multi-state process, populating different intermediate states. Despite the structural similarity of the two ligands, valuable distinctive features characterising their interaction with the G-quadruplex emerged from our multi-technique approach.


Assuntos
Alcaloides de Berberina/metabolismo , Berberina/metabolismo , DNA/metabolismo , Quadruplex G , Berberina/química , Alcaloides de Berberina/química , Dicroísmo Circular , DNA/química , DNA/genética , Humanos , Ligantes , Espalhamento a Baixo Ângulo , Análise Espectral Raman , Difração de Raios X
8.
Heliyon ; 6(1): e03311, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32021942

RESUMO

Accompanying human beings since the Paleolithic period, dogs has been recently regarded as a reliable model for the study of the gut microbiome connections with health and disease. In order to provide some glimpses on the connections between the gut microbiome layout and host behavior, we profiled the phylogenetic composition and structure of the canine gut microbiome of dogs with aggressive (n = 11), phobic (n = 13) and normal behavior (n = 18). Hormones' determination was made through Radio Immuno-Assay (RIA), and next generation sequencing of the V3-V4 gene region of the bacterial 16S rRNA was employed to determine gut microbiome composition. Our results did not evidence any significant differences of hormonal levels between the three groups. According to our findings, aggressive behavioral disorder was found to be characterized by a peculiar gut microbiome structure, with high biodiversity and enrichment in generally subdominant bacterial genera (i.e. Catenibacterium and Megamonas). On the other hand, phobic dogs were enriched in Lactobacillus, a bacterial genus with known probiotic and psychobiotic properties. Although further studies are needed to validate our findings, our work supports the intriguing opportunity that different behavioral phenotypes in dogs may be associated with peculiar gut microbiome layouts, suggesting possible connections between the gut microbiome and the central nervous system and indicating the possible adoption of probiotic interventions aimed at restoring a balanced host-symbiont interplay for mitigating behavioral disorders.

9.
Eur J Surg Oncol ; 46(4 Pt A): 632-637, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31812289

RESUMO

BACKGROUND: Aim of work was to investigate the prognostic impact of liver resection (LR) on locally advanced Intrahepatic Cholangiocarcinoma (IC) in comparison to alternative palliative chemotherapy (CTx). METHOD: A retrospective cohort study performed utilizing Surveillance, Epidemiology, and End Results (SEER) database to identify Locally advanced IC patients. Based on the American Joint Committee on Cancer (AJCC) Staging System, locally advanced IC was defined as: Stage III and IVa - 7th edition (7th-ed) or stage III - 8th edition (8th-ed). Study population were sub-classified into: LR group and a propensity score (PS) matched CTx group. RESULTS: In 7th-ed module, the median survival for LR group (n = 154) was 35 months, and the 3-year survival rate was 40.8%. In PS matched CTx group (n = 154); the median survival was 14 months and the 3-year survival rate was 5.5% (P = 0.007). Survival rates were superior for LR group over PS matched CTx group in 8th-ed module as well. Worse prognosis has been reported in LR patients above 65 years old (HR 2.618, P = 001) and in multifocal lesions (HR 1.890, P = 0.025). CONCLUSION: Hepatic resection was associated with a favorable impact on prognosis over chemotherapy for IC stage III and IVa of the 7th edition and for stage IIIb of 8th edition of AJCC staging system. Worse outcome has been observed in LR patients >65 years and with multifocal lesions. Randomized control studies are recommended to confirm the role of surgical resection in the management for advanced cases of IC, and to clarify the related prognostic factors.


Assuntos
Neoplasias dos Ductos Biliares/cirurgia , Ductos Biliares Intra-Hepáticos , Colangiocarcinoma/cirurgia , Hepatectomia/métodos , Neoplasias Primárias Múltiplas/cirurgia , Fatores Etários , Idoso , Antineoplásicos/uso terapêutico , Neoplasias dos Ductos Biliares/patologia , Colangiocarcinoma/patologia , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Invasividade Neoplásica , Estadiamento de Neoplasias , Neoplasias Primárias Múltiplas/patologia , Pontuação de Propensão , Estudos Retrospectivos , Programa de SEER , Taxa de Sobrevida , Carga Tumoral
10.
Sci Rep ; 8(1): 6105, 2018 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-29666447

RESUMO

Invertebrates represent the most plentiful component of marine biodiversity. To date, only few species have been documented for marine litter intake. Here, we report for the first time the presence of macroplastic debris in a jellyfish species. Such novel target to plastic pollution highlights an under studied vector of marine litter along marine trophic web, raising further concern over the impact on marine wildlife.


Assuntos
Plásticos , Comportamento Predatório , Cifozoários/fisiologia , Poluentes da Água , Animais , Ingestão de Alimentos , Monitoramento Ambiental , Cadeia Alimentar , Plásticos/efeitos adversos , Poluentes da Água/efeitos adversos
11.
Inflamm Res ; 67(7): 609-616, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29605872

RESUMO

The pathophysiology of psoriasis is very complex and involves an interplay between immune cells and keratinocytes. The keratinocyte production of calprotectin (S100A8/A9), induced by the inflammatory psoriatic milieu, may be involved in initiating immune cell invasion, as well as in propagating inflammation. However, the exact role of calprotectin in psoriasis remains unclear. Therapeutic approaches utilizing adalimumab, etanercept and ustekinumab are widely used in psoriatic treatment, but their anti-inflammatory mechanisms are not fully understood. The aim of this study was to investigate, by immunohistochemical analysis, the expression of the heterocomplex S100A8/A9 in lesional skin from psoriatic patients undergoing biological therapy with adalimumab, etanercept or ustekinumab. Our results showed that S100A8/A9, absent or present at very low level in skin biopsies from healthy subjects, is dramatically upregulated in each epidermal layer from psoriatic patients. Interestingly, calprotectin was mainly localized in keratinocyte nuclei from psoriatic patients, suggesting a role of S100A8/A9 in keratinocyte nuclear function. Furthermore, we have shown that the biological treatment induced a drastic reduction of S100A8/A9 expression in skin biopsies from treated patients, correlating with PASI reduction. Our results suggest that calprotectin may play a crucial role as a significant marker of inflammation in psoriasis, and that its reduction of expression may be considered a favourable prognostic marker in psoriasis.


Assuntos
Adalimumab , Anti-Inflamatórios não Esteroides , Calgranulina A/imunologia , Calgranulina B/imunologia , Fármacos Dermatológicos , Etanercepte , Psoríase/imunologia , Ustekinumab , Adalimumab/farmacologia , Adalimumab/uso terapêutico , Adulto , Anti-Inflamatórios não Esteroides/farmacologia , Anti-Inflamatórios não Esteroides/uso terapêutico , Terapia Biológica , Fármacos Dermatológicos/farmacologia , Fármacos Dermatológicos/uso terapêutico , Regulação para Baixo , Etanercepte/farmacologia , Etanercepte/uso terapêutico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psoríase/tratamento farmacológico , Pele/efeitos dos fármacos , Pele/imunologia , Ustekinumab/farmacologia , Ustekinumab/uso terapêutico
12.
Phys Chem Chem Phys ; 19(33): 22555-22563, 2017 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-28809977

RESUMO

UV Raman and Brillouin light scattering (BLS) experiments have been used in this study to explore the complex phase change behavior occurring in pH-responsive polysaccharide hydrogels as a function of temperature. Due to the different physical quantities measured by the two techniques, the joint analysis of Raman and BLS spectra has provided an unprecedented large-scale characterization of the molecular rearrangements and of the different kinds of hydrophilic and hydrophobic interactions that cooperate to determine the phase transformation observed in these hydrogels during the heating of the gel. As the main result, the analysis of the Raman and BLS spectra showed the existence of a correlation between the local (molecular) and collective properties of the gels during the phase transformation undergone by the system, which is markedly triggered by pH. The joint set of experimental results suggests a model according to which the mechanism of pH dependence in the hydrogels under investigation is dominated by the interactions involving the hydrophobic parts of the polymer skeleton, whereas the solvation process observed under heating of the gels is driven by the progressive distancing of the polymer domains among them, as monitored by the Brillouin sound velocity.

13.
Transplant Proc ; 49(4): 736-739, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28457384

RESUMO

INTRODUCTION: Hepatic artery thrombosis (HAT) is a well-recognized complication of liver transplantation (LT). HAT is an important risk factor for infectious, in particular hepatic abscess, which can cause graft loss and increasing morbidity and mortality. CASE REPORT: We present a case report of complicated LT in a 52-year-old Caucasian man with primary sclerosing cholangitis. In 2007 the patient was included on the waiting list in Padua for LT. In 2012 the patient underwent percutaneous transhepatic biliary drainage for bile duct stricture, complicated with acute pancreatitis. A diagnostic laparoscopy was performed with choledochotomy and Kehr's T tube drainage. On February 14, 2012, the patient underwent LT with arterial reconstruction and choledochojejunostomy. The postoperative course was complicated with HAT, multiple liver abscesses, and sepsis associated with bacteremia due to Enterococcus faecium despite massive intravenous antibiotic therapy and percutaneous drainages. On November 28, 2012, the patient underwent retransplantation. Four years after transplantation the patient is still in good general condition. CONCLUSION: Hepatic abscess formation secondary to HAT following LT is a major complication associated with important morbidity and mortality. In selected cases retransplantation should be considered as our case demonstrates.


Assuntos
Artéria Hepática/patologia , Transplante de Fígado/efeitos adversos , Reoperação , Trombose/etiologia , Humanos , Abscesso Hepático/etiologia , Masculino , Pessoa de Meia-Idade , Reoperação/efeitos adversos , Fatores de Risco , Fatores de Tempo
14.
Rev Sci Instrum ; 88(3): 033107, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28372390

RESUMO

A sensitive chemical aerosol Raman detector (CARD) has been developed for the trace detection and identification of chemical particles in the ambient atmosphere. CARD includes an improved aerosol concentrator with a concentration factor of about 40 and a CCD camera for improved detection sensitivity. Aerosolized isovanillin, which is relatively safe, has been used to characterize the performance of the CARD. The limit of detection (SNR = 10) for isovanillin in 15 s has been determined to be 1.6 pg/cm3, which corresponds to 6.3 × 109 molecules/cm3 or 0.26 ppb. While less sensitive, CARD can also detect gases. This paper provides a more detailed description of the CARD hardware and detection algorithm than has previously been published.

15.
Soft Matter ; 12(43): 8861-8868, 2016 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-27734051

RESUMO

The focus of the present work is to shed light on possible modifications of the molecular properties of polysaccharide hydrogels induced by the establishment of specific non-covalent interactions during the loading of a guest compound inside the gel phase. With this aim, a case study of the encapsulation of caffeine (Caf) inside cyclodextrin-based hydrogels, namely, cyclodextrin nanosponges (NS), is systematically investigated here by using UV Raman scattering experiments. The UV Raman spectra of the hydrogels, analysed as a function of temperature, concentration of the guest molecule loaded in the gel phase and pH, prove particularly informative both on the structural rearrangements of the hydrophobic/hydrophilic groups of the polymeric network and on the breaking/formation of specific guest-matrix interactions. Analysis of the temperature dependence of dynamical parameters, i.e., the dephasing time associated with specific vibrational modes of the polymer backbone, enables the proposal of a molecular picture in which the loading of Caf in NS hydrogels tends to favour access of the water solvent to the more hydrophobic portions of the polymer matrix, which is in turn reflected in a marked increase in the solvation of the whole system. The achievements of this work appear of interest with respect to the design of new possible strategies for controlling the diffusion/release of bioactive molecules inside hydrogel networks, besides corroborating the potential of UV Raman scattering experiments to give new molecular insights into complex phenomena affecting hydrogel phases.

16.
Phys Chem Chem Phys ; 18(19): 13478-86, 2016 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-27127808

RESUMO

During the last few decades it has been ascertained that base stacking is one of the major contributions stabilizing nucleic acid conformations. However, the understanding of the nature of the interactions involved in the stacking process remains under debate and it is a subject of theoretical and experimental studies. Structural similarity between purine bases (guanine and adenine) in DNA and the caffeine molecule makes caffeine an excellent model for the purine bases. The present study clearly shows that dipolar interactions play a fundamental role in determining stacking of purine molecules in solution. In order to reach this achievement, polarized ultraviolet Raman resonant scattering experiments have been carried out on caffeine aqueous solutions as a function of concentration and temperature. The investigation pointed out at the aggregation and solvation properties, particularly at elevated temperatures. Kubo-Anderson theory was used as a framework to investigate the non-coincidence effect (NCE) occurring in the totally symmetric breathing modes of the purine rings, and in the bending modes of the methyl groups of caffeine. The NCE concentration dependence shows that caffeine aggregation at 80 °C occurs by planar stacking of the hydrophobic faces. The data clearly indicate that dipolar interactions determine the reorientational motion of the molecules in solution and are the driving force for the stacking of caffeine. In parallel, the observed dephasing times imply a change in caffeine interactions as a function of temperature and concentration. A decrease, at low water content, of the dephasing time for the ring breathing vibration mode indicates that self-association alters the solvation structure that is detectable at low concentration. These results are in agreement with simulation predictions and serve as an important validation of the models used in those calculations.


Assuntos
Cafeína/química , Água/química , Adenina/química , Guanina/química , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Conformação de Ácido Nucleico , Purinas/química , Teoria Quântica , Soluções , Temperatura , Raios Ultravioleta
17.
Phys Chem Chem Phys ; 18(17): 12252-9, 2016 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-27081681

RESUMO

The fundamental question of how the reorganization of the hydrogen-bond (HB) network of water is influenced by the combination of nano-confinement and hydrophobic/hydrophilic solvation effects is addressed here using a spectroscopic study of water absorbed in a model, pH-sensitive polysaccharide hydrogel. The effects of temperature, hydration level and pH on the vibrational dynamics associated with the water molecules and the polymer skeleton are disentangled and analysed by a complementary and combined use of UV-Raman scattering and IR spectroscopy. The experimental data give evidence that the solvation effects in the hydrogel matrix are essentially dominated by the hydration of more hydrophobic parts of the polymer network, while the effect of pH on the HB reorganization of confined water molecules is found to be similar to that induced by cooling of the system. A tentative explanation of these results has been provided in terms of interplay between different kinds of interactions, i.e. hydrophobic vs. hydrophilic.

18.
Epidemiol Infect ; 144(7): 1463-72, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27029910

RESUMO

Mathematical modelling is an important tool for understanding the dynamics of the spread of infectious diseases, which could be the result of a natural outbreak or of the intentional release of pathogenic biological agents. Decision makers and policymakers responsible for strategies to contain disease, prevent epidemics and fight possible bioterrorism attacks, need accurate computational tools, based on mathematical modelling, for preventing or even managing these complex situations. In this article, we tested the validity, and demonstrate the reliability, of an open-source software, the Spatio-Temporal Epidemiological Modeler (STEM), designed to help scientists and public health officials to evaluate and create models of emerging infectious diseases, analysing three real cases of Ebola haemorrhagic fever (EHF) outbreaks: Uganda (2000), Gabon (2001) and Guinea (2014). We discuss the cases analysed through the simulation results obtained with STEM in order to demonstrate the capability of this software in helping decision makers plan interventions in case of biological emergencies.


Assuntos
Doenças Transmissíveis Emergentes/epidemiologia , Surtos de Doenças , Ebolavirus/fisiologia , Doença pelo Vírus Ebola/epidemiologia , Vigilância da População/métodos , Software/normas , Doenças Transmissíveis Emergentes/virologia , República Democrática do Congo/epidemiologia , Gabão/epidemiologia , Guiné/epidemiologia , Doença pelo Vírus Ebola/virologia , Humanos , Reprodutibilidade dos Testes , Uganda/epidemiologia
19.
Struct Dyn ; 3(2): 023604, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26798835

RESUMO

High-energy density extreme ultraviolet radiation delivered by the FERMI seeded free-electron laser has been used to create an exotic nonequilibrium state of matter in a titanium sample characterized by a highly excited electron subsystem at temperatures in excess of 10 eV and a cold solid-density ion lattice. The obtained transient state has been investigated through ultrafast absorption spectroscopy across the Ti M2,3-edge revealing a drastic rearrangement of the sample electronic structure around the Fermi level occurring on a time scale of about 100 fs.

20.
Phys Chem Chem Phys ; 17(15): 10274-82, 2015 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-25798878

RESUMO

A detailed experimental and theoretical vibrational analysis of hydrogels of ß-cyclodextrin nanosponges (ß-CDNS), obtained by polymerization of ß-cyclodextrin (ß-CD) with the cross-linking agent ethylenediaminetetraacetic acid (EDTA), is reported here. Thorough structural characterization is achieved by exploiting the complementary selection rules of FTIR-ATR and Raman spectroscopies and by supporting the spectral assignments by DFT calculations of the spectral profiles. The combined analysis of the FTIR-ATR spectra of the polymers hydrated with H2O and D2O allowed us to isolate the HOH bending of water molecules not involved in symmetrical, tetrahedral environments. The analysis of the HOH bending mode was carried out as a function of temperature, showing the existence of a supercooled state of the water molecules. The highest level of cooperativity of the hydrogen bond scheme was reached at a value of the ß-CD/EDTA molar ratio n = 6. Finally, the connectivity pattern of "uncoupled" water molecules bound to the nanosponge backbone was found to be weakened by increasing T. The temperature above which the population of non-tetracoordinated water molecules becomes predominant turned out to be independent of the parameter n.

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