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1.
Eur J Neurol ; : e16311, 2024 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-38646961

RESUMEN

BACKGROUND AND PURPOSE: Coma is an independent predictor of poor clinical outcomes in cerebral venous thrombosis (CVT). We aimed to describe the association of age, sex, and radiological characteristics of adult coma patients with CVT. METHODS: We used data from the international, multicentre prospective observational BEAST (Biorepository to Establish the Aetiology of Sinovenous Thrombosis) study. Only positively associated variables with coma with <10% missing data in univariate analysis were considered for the multivariate logistic regression model. RESULTS: Of the 596 adult patients with CVT (75.7% women), 53 (8.9%) patients suffered coma. Despite being a female-predominant disease, the prevalence of coma was higher among men than women (13.1% vs. 7.5%, p = 0.04). Transverse sinus thrombosis was least likely to be associated with coma (23.9% vs. 73.3%, p < 0.001). The prevalence of superior sagittal sinus thrombosis was higher among men than women in the coma sample (73.6% vs. 37.5%, p = 0.01). Men were significantly older than women, with a median (interquartile range) age of 51 (38.5-60) versus 40 (33-47) years in the coma (p = 0.04) and 44.5 (34-58) versus 37 (29-48) years in the non-coma sample (p < 0.001), respectively. Furthermore, an age- and superior sagittal sinus-adjusted multivariate logistic regression model found male sex (odds ratio = 1.8, 95% confidence interval [CI] = 1.0-3.4, p = 0.04) to be an independent predictor of coma in CVT, with an area under the receiver operating characteristic curve of 0.61 (95% CI = 0.52-0.68, p = 0.01). CONCLUSIONS: Although CVT is a female-predominant disease, men were older and nearly twice as likely to suffer from coma than women.

2.
Eur Spine J ; 32(10): 3360-3369, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37336795

RESUMEN

PURPOSE: Intraoperative muscle motor evoked potentials (m-MEPs) are widely used in spinal surgery with the aim of identifying a damage to spinal cord at a reversible stage. Generally, lower limb m-MEPs are recorded from abductor hallucis [AH] and the tibialis anterior [TA]. The purpose of this work is to study an unselected population by recording the m-MEPs from TA, AH and extensor digitorum brevis (EDB), with the aim of identifying the most adjustable and stable muscles responses intraoperatively. METHODS: Transcranially electrically induced m-MEPs were intraoperative recorded in a total of 107 surgical procedures. m-MEPs were recorded by a needle electrode placed in the muscle from TA, AH and EDB muscles in the lower extremities. RESULTS: Overall monitorability (i.e., at least 1 Lower Limb m-MEP recordable) was 100/107 (93.5%). In the remaining 100 surgeries in 3 cases, the only muscle that could be recorded at baseline was one AH, and in other 2 the EDB. Persistence (i.e., the recordability of m-MEP from baseline to the end of surgery) was 88.7% for TA, 89.8% for AH and 93.8% for EDB. CONCLUSION: In our series, EDB m-MEPs have demonstrated a recordability superior to TA and a stability similar to AH. The explanations may be different and range from changes in the excitability of the cortical motor neuron to the different sensitivity to ischemia of the spinal motor neuron. EDB can be used alternatively or can be added to TA and AH as a target muscle of the lower limb in spinal surgery.


Asunto(s)
Monitoreo Intraoperatorio , Médula Espinal , Humanos , Monitoreo Intraoperatorio/métodos , Médula Espinal/cirugía , Columna Vertebral/cirugía , Músculo Esquelético/fisiología , Procedimientos Neuroquirúrgicos , Potenciales Evocados Motores/fisiología
3.
Angew Chem Int Ed Engl ; 62(31): e202303585, 2023 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-37260054

RESUMEN

Here, we report a general approach to the synthesis of the difluoroalkyl bicycloalkanes (CF2 -BCAs), as structural surrogates of aryl ketones and ethers. The chemistry is driven by a dihydrobenzoacridine photocatalyst, that engages in a catalytic electron-donor acceptor (EDA) complex, or directly reduces the fluorinated substrate. These two convergent manifolds lead to the generation of the R-CF2 radical, that reacts with the [1.1.1]- or [3.1.1.]-propellane. The method is extremely general, and extendable to complex bioactive molecules (30 examples, up to 87 % yield). The structural features of the CF2 -BCP hybrid bioisostere were investigated by single crystal X-ray. Finally, we synthesised a CF2 -BCP analogue of a Leukotriene A4 hydrolase inhibitor, replacing the original aryl ether motif. In silico docking studies indicated that this new analogue maintains the same arrangement within the enzyme pocket, profiling the use of the CF2 -BCA hybrid bioisostere in medicinal chemistry settings.

4.
J Am Chem Soc ; 144(31): 14021-14025, 2022 08 10.
Artículo en Inglés | MEDLINE | ID: mdl-35881505

RESUMEN

As the natural-born photoelectrolyzer for oxygen delivery, photosystem II (PSII) is hardly replicated with man-made constructs. However, building on the "quantasome" hypothesis ( Science 1964, 144, 1009-1011), PSII mimicry can be pared down to essentials by shaping a photocatalytic ensemble (from the Greek term "soma" = body) where visible-light quanta trigger water oxidation. PSII-inspired quantasomes (QS) readily self-assemble into hierarchical photosynthetic nanostacks, made of bis-cationic perylenebisimides (PBI2+) as chromophores and deca-anionic tetraruthenate polyoxometalates (Ru4POM) as water oxidation catalysts ( Nat. Chem. 2019, 11, 146-153). A combined supramolecular and click-chemistry strategy is used herein to interlock the PBI-QS with tetraethylene glycol (TEG) cross-linkers, yielding QS-TEGlock with increased water solvation, controlled growth, and up to a 340% enhancement of the oxygenic photocurrent compared to the first generation QS, as probed on 3D-inverse opal indium tin oxide electrodes at 8.5 sun irradiance (λ > 450 nm, 1.28 V vs RHE applied bias, TOFmax = 0.096 ± 0.005 s-1, FEO2 > 95%). Action spectra, catalyst mass-activity, light-management, photoelectrochemical impedance spectroscopy (PEIS) together with Raman mapping of TEG-templated hydration shells point to a key role of the cross-linked PBI/Ru4POM nanoarrays, where the interplay of hydrophilic/hydrophobic domains is reminiscent of PSII-rich natural thylakoids.


Asunto(s)
Oxígeno , Fotosíntesis , Humanos , Imidas , Luz , Oxidación-Reducción , Oxígeno/química , Perileno/análogos & derivados , Complejo de Proteína del Fotosistema II/química , Agua/química
5.
Ann Neurol ; 90(5): 777-788, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34459509

RESUMEN

OBJECTIVE: Cerebral venous thrombosis (CVT) is an uncommon form of stroke affecting mostly young individuals. Although genetic factors are thought to play a role in this cerebrovascular condition, its genetic etiology is not well understood. METHODS: A genome-wide association study was performed to identify genetic variants influencing susceptibility to CVT. A 2-stage genome-wide study was undertaken in 882 Europeans diagnosed with CVT and 1,205 ethnicity-matched control subjects divided into discovery and independent replication datasets. RESULTS: In the overall case-control cohort, we identified highly significant associations with 37 single nucleotide polymorphisms (SNPs) within the 9q34.2 region. The strongest association was with rs8176645 (combined p = 9.15 × 10-24 ; odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.76-2.31). The discovery set findings were validated across an independent European cohort. Genetic risk score for this 9q34.2 region increases CVT risk by a pooled estimate OR = 2.65 (95% CI = 2.21-3.20, p = 2.00 × 10-16 ). SNPs within this region were in strong linkage disequilibrium (LD) with coding regions of the ABO gene. The ABO blood group was determined using allele combination of SNPs rs8176746 and rs8176645. Blood groups A, B, or AB, were at 2.85 times (95% CI = 2.32-3.52, p = 2.00 × 10-16 ) increased risk of CVT compared with individuals with blood group O. INTERPRETATION: We present the first chromosomal region to robustly associate with a genetic susceptibility to CVT. This region more than doubles the likelihood of CVT, a risk greater than any previously identified thrombophilia genetic risk marker. That the identified variant is in strong LD with the coding region of the ABO gene with differences in blood group prevalence provides important new insights into the pathophysiology of CVT. ANN NEUROL 2021;90:777-788.


Asunto(s)
Predisposición Genética a la Enfermedad/genética , Estudio de Asociación del Genoma Completo , Trombosis Intracraneal/genética , Trombosis de la Vena/genética , Adulto , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Trombofilia/genética
6.
J Neurol Neurosurg Psychiatry ; 93(7): 686-692, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35508372

RESUMEN

OBJECTIVE: To explore the impact of antithrombotic therapy discontinuation in the postacute phase of cervical artery dissection (CeAD) on the mid-term outcome of these patients. METHODS: In a cohort of consecutive patients with first-ever CeAD, enrolled in the setting of the multicentre Italian Project on Stroke in Young Adults Cervical Artery Dissection, we compared postacute (beyond 6 months since the index CeAD) outcomes between patients who discontinued antithrombotic therapy and patients who continued taking antithrombotic agents during follow-up. Primary outcome was a composite of ischaemic stroke and transient ischaemic attack. Secondary outcomes were (1) Brain ischaemia ipsilateral to the dissected vessel and (2) Recurrent CeAD. Associations with the outcome of interest were assessed by the propensity score (PS) method. RESULTS: Of the 1390 patients whose data were available for the outcome analysis (median follow-up time in patients who did not experience outcome events, 36.0 months (25th-75th percentile, 62.0)), 201 (14.4%) discontinued antithrombotic treatment. Primary outcome occurred in 48 patients in the postacute phase of CeAD. In PS-matched samples (201 vs 201), the incidence of primary outcomes among patients taking antithrombotics was comparable with that among patients who discontinued antithrombotics during follow-up (5.0% vs 4.5%; p(log rank test)=0.526), and so was the incidence of the secondary outcomes ipsilateral brain ischaemia (4.5% vs 2.5%; p(log rank test)=0.132) and recurrent CeAD (1.0% vs 1.5%; p(log rank test)=0.798). CONCLUSIONS: Discontinuation of antithrombotic therapy in the postacute phase of CeAD does not appear to increase the risk of brain ischaemia during follow-up.


Asunto(s)
Isquemia Encefálica , Accidente Cerebrovascular , Disección de la Arteria Vertebral , Arterias , Isquemia Encefálica/complicaciones , Fibrinolíticos/uso terapéutico , Humanos , Accidente Cerebrovascular/complicaciones , Disección de la Arteria Vertebral/complicaciones , Disección de la Arteria Vertebral/tratamiento farmacológico , Disección de la Arteria Vertebral/epidemiología , Adulto Joven
7.
Neuroradiology ; 64(7): 1367-1372, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35034151

RESUMEN

PURPOSE: Intracerebral hemorrhage (ICH) is an uncommon but deadly event in patients with COVID-19 and its imaging features remain poorly characterized. We aimed to describe the clinical and imaging features of COVID-19-associated ICH. METHODS: Multicenter, retrospective, case-control analysis comparing ICH in COVID-19 patients (COV19 +) versus controls without COVID-19 (COV19 -). Clinical presentation, laboratory markers, and severity of COVID-19 disease were recorded. Non-contrast computed tomography (NCCT) markers (intrahematoma hypodensity, heterogeneous density, blend sign, irregular shape fluid level), ICH location, and hematoma volume (ABC/2 method) were analyzed. The outcome of interest was ultraearly hematoma growth (uHG) (defined as NCCT baseline ICH volume/onset-to-imaging time), whose predictors were explored with multivariable linear regression. RESULTS: A total of 33 COV19 + patients and 321 COV19 - controls with ICH were included. Demographic characteristics and vascular risk factors were similar in the two groups. Multifocal ICH and NCCT markers were significantly more common in the COV19 + population. uHG was significantly higher among COV19 + patients (median 6.2 mL/h vs 3.1 mL/h, p = 0.027), and this finding remained significant after adjustment for confounding factors (systolic blood pressure, antiplatelet and anticoagulant therapy), in linear regression (B(SE) = 0.31 (0.11), p = 0.005). This association remained consistent also after the exclusion of patients under anticoagulant treatment (B(SE) = 0.29 (0.13), p = 0.026). CONCLUSIONS: ICH in COV19 + patients has distinct NCCT imaging features and a higher speed of bleeding. This association is not mediated by antithrombotic therapy and deserves further research to characterize the underlying biological mechanisms.


Asunto(s)
COVID-19 , Anticoagulantes , Biomarcadores , COVID-19/complicaciones , Hemorragia Cerebral/complicaciones , Hemorragia Cerebral/diagnóstico por imagen , Hematoma/diagnóstico por imagen , Humanos , Estudios Retrospectivos
8.
J Sci Food Agric ; 102(2): 844-850, 2022 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-34231921

RESUMEN

BACKGROUND: Beyond nutrition, fruits and vegetables can be considered as natural sources of bioactive molecules, for which beneficial effects on human health are widely recognised. To improve food quality, soilless growing systems could represent a good strategy for promoting a sustainable food production chain, although the nutritional and nutraceutical properties of their products should be investigated in depth. The main quality traits and the volatile and non-volatile secondary metabolites of Solanum lycopersicum L., Petroselinum crispum (Mill.) Fuss and Ocimun basilicum L. grown in an aquaponics system and in organic farming were quantified and compared. RESULTS: On a fresh basis, soil-grown P. crispum and O. basilicum showed significantly higher total phenolics and antioxidant activity compared to aquaponic crops, whereas, on a dry basis, both plants showed opposite results. Soil-grown S. lycopersicum was significantly richer in total phenolics, whereas the aquaponic type showed a higher antioxidant activity. Aquaponics induced the accumulation of resveratrol in P. crispum, rosmarinic acid and myricetin in O. basilicum, and lycopene in S. lycopersicum. Among the volatile compounds, in O. basilicum, linalool was the main constituent in both treatments, whereas τ-cadinol represented the second constituent in aquaponic crops. The volatile profiles of P. crispum did not differ significantly between the two cultivation methods. CONCLUSION: The overall quality of organic and aquaponics cultures appeared to be comparable. The results showed that aquaponic farming method can be an innovative, rapid and sustainable way of producing quality food. © 2021 Society of Chemical Industry.


Asunto(s)
Frutas/química , Frutas/crecimiento & desarrollo , Hidroponía/métodos , Fitoquímicos/química , Verduras/química , Verduras/crecimiento & desarrollo , Antioxidantes/química , Productos Agrícolas/química , Productos Agrícolas/crecimiento & desarrollo , Calidad de los Alimentos , Hidroponía/instrumentación , Agricultura Orgánica , Fenoles/química
9.
Stroke ; 51(5): 1470-1476, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32200757

RESUMEN

Background and Purpose- We investigated whether subarachnoid extension (SAHE) of intracerebral hemorrhage (ICH) is associated with hematoma expansion (HE). Methods- Retrospective analysis of patients with primary spontaneous ICH admitted at 3 academic hospitals in Italy. The study population was divided into a development and a replication cohort. SAHE was rated on baseline noncontrast computed tomography by investigators blinded to clinical data. The main outcome of interest was HE, defined as ICH growth >33% mL and/or >6 mL. Predictors of HE were explored with multivariable logistic regression stratified by ICH location (lobar versus nonlobar). Results- A total of 360 and 192 patients were included in the development and replication cohort, respectively. SAHE was identified with good interrater reliability (K=0.82), and its frequency was 27.8% in the development and 24.5% in the replication cohort. In univariate analysis, HE was more common in patients with SAHE (52.0% versus 27.3%; P<0.001). When controlling for confounders in logistic regression, SAHE was an independent predictor of lobar HE (odds ratio, 6.00 [95% CI, 2.16-16.64]; P=0.001) whereas there was no association with HE in nonlobar ICH (odds ratio, 0.55 [95% CI, 0.17-1.84]; P=0.334). The increased risk of HE in lobar ICH with SAHE was confirmed in the replication cohort (odds ratio, 3.46 [95% CI, 1.07-11.20]; P=0.038). Conclusions- SAHE predicts HE in lobar ICH. This may improve the stratification of HE risk in clinical practice or future trials targeting HE. Further research is needed to confirm our findings and characterize the underlying biological mechanisms.


Asunto(s)
Encéfalo/patología , Hemorragia Cerebral/epidemiología , Hemorragia Cerebral/patología , Hematoma/patología , Anciano , Estudios de Cohortes , Femenino , Hematoma/complicaciones , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Retrospectivos , Tomografía Computarizada por Rayos X
10.
Org Biomol Chem ; 18(31): 6047-6052, 2020 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-32705111

RESUMEN

We report a novel way to promote photochemical benzylic radical arylations using Pd nanostructures. Traditional benzylic radical reaction pathways are challenged by the presence of metal centres that provoke unprecedented regioselectivity towards more synthetically relevant C(sp3)-C(sp2) couplings. This new C-H activation pathway is rationalised by means of a pseudo-persistent radical effect facilitated by metal centres. We show the mechanistic and computational aspects of the heterogeneous photocatalytic processes that are the root of this drastic change in reactivity.

11.
Neurocrit Care ; 32(3): 804-811, 2020 06.
Artículo en Inglés | MEDLINE | ID: mdl-31342451

RESUMEN

BACKGROUND AND PURPOSE: The BAT, BRAIN, and HEP scores have been proposed to predict hematoma expansion (HE) with noncontrast computed tomography (NCCT). We sought to validate these tools and compare their diagnostic performance. METHODS: We retrospectively analyzed two cohorts of patients with primary intracerebral hemorrhage. HE expansion was defined as volume growth > 33% or > 6 mL. Two raters analyzed NCCT scans and calculated the scores, blinded to clinical and imaging data. The inter-rater reliability was assessed with the interclass correlation statistic. Discrimination and calibration were calculated with area under the curve (AUC) and Hosmer-Lemeshow χ2 statistic, respectively. AUC comparison between different scores was explored with DeLong test. We also calculated the sensitivity, specificity, positive, and negative predictive values of the dichotomized scores with cutoffs identified with the Youden's index. RESULTS: A total of 230 subjects were included, of whom 86 (37.4%) experienced HE. The observed AUC for HE were 0.696 for BAT, 0.700 for BRAIN, and 0.648 for HEP. None of the scores had a significantly superior AUC compared with the others (all p > 0.4). All the scores had good calibration (all p > 0.3) and good-to-excellent inter-rater reliability (interclass correlation > 0.8). BAT ≥ 3 showed the highest specificity (0.81), whereas BRAIN ≥ 6 had the highest sensitivity (0.76). CONCLUSIONS: The BAT, BRAIN, and HEP scores can predict HE with acceptable discrimination and require just a baseline NCCT scan. These tools may be used to stratify the risk of HE in clinical practice or randomized controlled trials.


Asunto(s)
Hemorragia Cerebral/diagnóstico por imagen , Medición de Riesgo/métodos , Anciano , Anciano de 80 o más Años , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Retrospectivos , Tomografía Computarizada por Rayos X/métodos
12.
J Am Chem Soc ; 141(11): 4531-4535, 2019 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-30830774

RESUMEN

Photogenerated holes in nanometric semiconductors, such as TiO2, constitute remarkable powerful electrophilic centers, capable of capturing an electron from numerous donors such as ethers, or nonactivated substrates like toluene or acetonitrile, and constitute an exceptionally clean and efficient source of free radicals. In contrast with typical free radical precursors, semiconductors generate single radicals (rather than pairs), where the precursors can be readily removed by filtration or centrifugation after use, thus making it a convenient tool in organic chemistry. The process can be described as an example of dystonic proton coupled electron transfer.

13.
Cephalalgia ; 39(10): 1267-1276, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31060368

RESUMEN

INTRODUCTION: To describe clinical, neuroimaging, and laboratory features of a large cohort of Italian patients with reversible cerebral vasoconstriction syndrome. METHODS: In the setting of the multicenter Italian Project on Stroke at Young Age (IPSYS), we retrospectively enrolled patients with a diagnosis of definite reversible cerebral vasoconstriction syndrome according to the International Classification of Headache Disorders (ICHD)-3 beta criteria (6.7.3 Headache attributed to reversible cerebral vasoconstriction syndrome, imaging-proven). Clinical manifestations, neuroimaging, treatment, and clinical outcomes were evaluated in all patients. Characteristics of reversible cerebral vasoconstriction syndrome without typical causes ("idiopathic reversible cerebral vasoconstriction syndrome") were compared with those of reversible cerebral vasoconstriction syndrome related to putative causative factors ("secondary reversible cerebral vasoconstriction syndrome"). RESULTS: A total of 102 patients (mean age, 47.2 ± 13.9 years; females, 85 [83.3%]) qualified for the analysis. Thunderclap headache at presentation was reported in 69 (67.6%) patients, and it typically recurred in 42 (60.9%). Compared to reversible cerebral vasoconstriction syndrome cases related to putative etiologic conditions (n = 21 [20.6%]), patients with idiopathic reversible cerebral vasoconstriction syndrome (n = 81 [79.4%]) were significantly older (49.2 ± 13.9 vs. 39.5 ± 11.4 years), had more frequently typical thunderclap headache (77.8% vs. 28.6%) and less frequently neurological complications (epileptic seizures, 11.1% vs. 38.1%; cerebral infarction, 6.1% vs. 33.3%), as well as concomitant reversible brain edema (25.9% vs. 47.6%). CONCLUSIONS: Clinical manifestations and putative etiologies of reversible cerebral vasoconstriction syndrome in our series are slightly different from those observed in previous cohorts. This variability might be partly related to the coexistence of precipitating conditions with a putative etiologic role on disease occurrence.


Asunto(s)
Vasoespasmo Intracraneal/etiología , Vasoespasmo Intracraneal/patología , Adulto , Femenino , Cefaleas Primarias/etiología , Humanos , Italia , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Síndrome
14.
J Org Chem ; 84(18): 11450-11457, 2019 09 20.
Artículo en Inglés | MEDLINE | ID: mdl-31343881

RESUMEN

We investigate the effects of small admixtures of protic solvent molecules, such as water and alcohols, on the ultrafast dynamics of diphenylcarbene in acetonitrile at room temperature. Broadband transient absorption measurements and quantum mechanics/molecular mechanics molecular dynamics simulations allow elucidating the dominant reaction mechanism of an intermediate hydrogen-bonded complex between singlet diphenylcarbene and a protic solvent molecule, thus competing with intersystem crossing. Analysis of the data indicates that complex formation is a diffusion-controlled process with orientational requirements. The reaction path involving a benzhydryl cation is less likely in neat bulkier alcohols, as it requires the interaction of the carbene with a protic solvent molecule being part of a hydrogen-bonded network. The simulations indicate a further reaction path toward O-H insertion and two side reactions depending on the involved protic solvent species. Thus, we established that not only the number but also the chemical nature of the protic solvent molecule determine which reaction path is pursued.

15.
Semin Neurol ; 39(1): 61-72, 2019 02.
Artículo en Inglés | MEDLINE | ID: mdl-30743293

RESUMEN

Stroke remains one of the leading determinants of death and severe disability worldwide. It is a medical emergency with a narrow window for recognition and administration of outcome-modifying treatment in the emergency department. Ischemic stroke accounts for the majority of cerebrovascular events and revascularization therapies such as intravenous thrombolysis and endovascular thrombectomy are the mainstays of treatment in carefully selected patients. Intracerebral hemorrhage is less common but remains the deadliest type of stroke. Blood pressure reduction and hemostatic treatment in case of coagulopathy are the cornerstones of acute intracerebral hemorrhage treatment. Admission to dedicated stroke units is associated with improved outcome in patients suffering from acute stroke.


Asunto(s)
Manejo de la Enfermedad , Accidente Cerebrovascular/diagnóstico , Accidente Cerebrovascular/terapia , Humanos
16.
J Phys Chem A ; 123(47): 10224-10229, 2019 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-31661275

RESUMEN

Upon UVA irradiation, aryl halides can undergo dehalogenation in the presence of bases and methanol as a hydrogen donor. This catalyst-free photochemical dehalogenation is furnished through a facile radical chain reaction under mild conditions. The chain reaction follows UVA irradiation of the reaction mixture in a transition-metal-free environment. Mechanistic studies support a chain mechanism in which initiation involves absorption by a methoxide-bromoarene complex facilitated by halogen-bonding interactions. The methoxide-bromine interaction leads to a weakened Br-C bond that is prone to facile cleavage during the initiation and propagation steps.

17.
J Am Chem Soc ; 140(49): 17271-17277, 2018 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-30430835

RESUMEN

The chemistry of arylnitrenes is dominated by their triplet ground states and excited open-shell singlet states. This results in radical-type reactions and unwanted rearrangements, which diminish the use of arylnitrenes as intermediates in organic synthesis. While the closed-shell singlet states of arylnitrenes are expected to undergo useful chemical transformations (comparable to the closed-shell singlet states of carbenes), these states are too high in energy to be chemically accessible. When triplet pentafluorophenylnitrene is interacting with the Lewis acid BF3 under the conditions of matrix isolation, a Lewis acid-base complex consisting of the closed-shell singlet state of the nitrene and two molecules of BF3 is formed. Although the closed-shell singlet state of pentafluorophenylnitrene is calculated (CCSD(T)) to lie more than 25 kcal/mol above its triplet ground state, the reaction with BF3 results in switching the spin state from triplet to singlet. The formation of the singlet complex was monitored by IR, UV-vis, and EPR spectroscopy. DFT, CCSD(T), and CASPT2 calculations confirm the experimental findings.

18.
Chemistry ; 24(68): 18043-18051, 2018 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-30230615

RESUMEN

The reactions of the three triplet ground state arylcarbenes diphenylcarbene 1, fluorenylidene 2, and dibenzocycloheptadienylidene 3 with the Lewis acids H2 O, ICF3 , and BF3 were studied under the conditions of matrix isolation. H2 O was selected as typical hydrogen bond donor, ICF3 as halogen bond donor, and BF3 as strong Lewis acid. H2 O forms hydrogen-bonded complexes of the singlet carbenes with 1 and 2, but not with 3. This is rationalized by the larger singlet-triplet gap of 3, which does not allow to stabilize the singlet state below the triplet state by hydrogen bonding. With ICF3 , both 1 and 3 form halogen-bonded complexes of the singlet states of the carbenes. This indicates that halogen bonding stabilizes singlet carbenes more than hydrogen bonding. Carbene 2 reacts differently from 1 and 3 by forming an iodonium ylide, thus avoiding antiaromatic destabilization of the fluorenyl unit. With BF3 , all three carbenes form zwitterionic Lewis acid/base complexes.

19.
J Am Chem Soc ; 139(37): 13024-13030, 2017 09 20.
Artículo en Inglés | MEDLINE | ID: mdl-28826206

RESUMEN

The reaction of triplet tetrachlorocyclopentadienylidene with BF3 in rare gas matrices yields a zwitterion consisting of a cyclopentadienyl cation bearing a positive charge and a negatively charged BF3 unit. IR and UV-vis spectra as well as the absence of EPR signals demonstrate a singlet ground state of the zwitterion, and its calculated geometry and magnetic properties clearly reveal a strong antiaromatic character. The zwitterion is highly labile and by visible or IR irradiation rearranges via a 1,2-fluorine migration from boron to carbon. Interaction with a second molecule of BF3 stabilizes the zwitterion and suppresses the fluorine migration, thus providing a convenient and efficient synthesis of an antiaromatic molecule under very mild conditions.

20.
Neuroradiology ; 59(6): 571-575, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28497262

RESUMEN

PURPOSE: The aim of this study was to test the hypothesis that patients with spontaneous cervical artery dissection (CeAD) have increased arterial tortuosity, and the objective quantification of such a tortuosity may aid in the identification of subjects at increased risk of disease. METHODS: In the setting of a hospital-based, case-control study, we used the vertebral tortuosity index (VTI) measured on magnetic resonance angiography, a validated method for the assessment and quantification of arterial tortuosity, to compare the degree of tortuosity in a series of consecutive patients with spontaneous CeAD and of age- and sex-matched patients with ischemic stroke unrelated to CeAD (non-CeAD IS) and stroke-free subjects. RESULTS: The study group was composed of 102 patients with CeAD (mean age, 44.5 ± 7.8 years; 66.7% men), 102 with non-CEAD IS, and 102 stroke-free subjects. The VTI was higher in the group of patients with CeAD (median, 7.3; 25th-75th percentile, 10.2) compared with that of non-CeAD IS (median, 3.4; 25th-75th percentile, 4.4) and of stroke-free subjects (median, 4.0; 25th-75th percentile, 2.9; p ≤ 0.001), and was independently associated to the risk of CeAD (OR, 1.18; 95% CI, 1.09-1.29) in multivariable regression analysis. The degree of tortuosity also tended to be higher in CeAD patients who experienced short-term recurrence (5.8%; median, 20.2; 25th-75th percentile, 31.2) than in those without recurrent events (median, 7.2; 25th-75th percentile, 9.4; p = 0.074). CONCLUSION: CeAD patients exhibit increased arterial tortuosity. This might have potential implications for better understanding of the pathophysiology of the disease as well as clinical utility in evaluation, prognostication, and decision-making of affected individuals.


Asunto(s)
Arterias/anomalías , Inestabilidad de la Articulación/diagnóstico por imagen , Angiografía por Resonancia Magnética , Enfermedades Cutáneas Genéticas/diagnóstico por imagen , Malformaciones Vasculares/diagnóstico por imagen , Disección de la Arteria Vertebral/diagnóstico por imagen , Adulto , Arterias/diagnóstico por imagen , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo
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