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1.
Gastroenterol Hepatol ; 47(7): 750-758, 2024.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-38219960

RESUMO

OBJECTIVE: The recommendations of the Spanish Ministry of Health on vaccination in risk groups include mesalazine among the treatments with a possible negative effect on its effectiveness. However, this is not the recommendation of most experts. Our objective was to evaluate the effect of mesalazine on the humoral response to the SARS-CoV-2 vaccine in patients with inflammatory bowel disease (IBD). METHODS: VACOVEII is a Spanish, prospective, multicenter study promoted by GETECCU, which evaluates the effectiveness of the SARS-CoV-2 vaccine in patients with IBD. This study includes IBD patients who have recieved the full vaccination schedule and without previous COVID-19 infection. Seroconversion was set at 260BAU/mL (centralized determination) and was assessed 6 months after full vaccination. In this subanalysis of the study, we compare the effectiveness of the vaccine between patients treated with mesalazine and patients without treatment. RESULTS: A total of 124 patients without immunosuppressive therapy were included, of which 32 did not receive any treatment and 92 received only mesalazine. Six months after full vaccination, no significant differences are observed in the mean concentrations of IgG anti-S between both groups. In the multivariate analysis, antibody titers were independently associated with the use of mRNA vaccines and with SARS-CoV-2 infection. CONCLUSION: Mesalazine does not have a negative effect on the response to SARS-CoV-2 vaccines in IBD patients.


Assuntos
Anti-Inflamatórios não Esteroides , Vacinas contra COVID-19 , COVID-19 , Doenças Inflamatórias Intestinais , Mesalamina , Humanos , Mesalamina/uso terapêutico , Feminino , Estudos Prospectivos , Masculino , Vacinas contra COVID-19/imunologia , Doenças Inflamatórias Intestinais/tratamento farmacológico , Pessoa de Meia-Idade , Adulto , Anti-Inflamatórios não Esteroides/uso terapêutico , COVID-19/prevenção & controle , COVID-19/imunologia , Anticorpos Antivirais/sangue , Vacinação , Idoso , Soroconversão , Eficácia de Vacinas , SARS-CoV-2/imunologia
2.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-38007154

RESUMO

BACKGROUND: The response to SARS-CoV-2 vaccination decreases in inflammatory bowel disease (IBD) patients, specially under anti-TNF treatment. However, data on medium-term effectiveness are limited, specially using new recommended seroconversion rate (>260BAU/mL). Our aim was to evaluate the 6-month>260 BAU-seroconversion rate after full vaccination and after booster-dose. METHODS: VACOVEII is a Spanish multicenter, prospective study promoted by GETECCU. IBD patients full vaccinated against SARS-CoV-2 and without previous COVID-19 infection, treated or not with immunosuppressants, were included. The booster dose was administered 6 months after the full vaccination. Seroconversion was set at 260BAU/mL, according to most recent recommendations and was assessed 6 months after the full vaccination and 6 months after booster-dose. RESULTS: Between October 2021 and March 2022, 313 patients were included (124 no treatment or mesalazine; 55 immunomodulators; 87 anti-TNF; 19 anti-integrin; and 28 ustekinumab). Most patients received mRNA-vaccines (86%). Six months after full vaccination, overall seroconversion rate was 44.1%, being significantly lower among patients on anti-TNF (19.5%, p<0.001) and ustekinumab (35.7%, p=0.031). The seroconversion rate after booster was 92%. Again, anti-TNF patients had a significantly lower seroconversion rate (67%, p<0.001). mRNA-vaccine improved seroconversion rate (OR 11.720 [95% CI 2.26-60.512]). CONCLUSION: The full vaccination regimen achieves suboptimal response in IBD patients, specially among those anti-TNF or ustekinumab. The booster dose improves seroconversion rate in all patients, although it remains limited in those treated with anti-TNF. These results reinforce the need to prioritize future booster doses in patients on immunosuppressants therapy, specially under anti-TNF, and using mRNA-vaccines.

3.
HGG Adv ; 4(3): 100213, 2023 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-37457373

RESUMO

Contraction of the human sarcomere is the result of interactions between myosin cross-bridges and actin filaments. Pathogenic variants in genes such as MYH7, TPM1, and TNNI3 that encode parts of the cardiac sarcomere cause muscle diseases that affect the heart, such as dilated cardiomyopathy and hypertrophic cardiomyopathy. In contrast, pathogenic variants in homologous genes such as MYH2, TPM2, and TNNI2 that encode parts of the skeletal muscle sarcomere cause muscle diseases affecting skeletal muscle, such as distal arthrogryposis (DA) syndromes and skeletal myopathies. To date, there have been few reports of genes (e.g., MYH7) encoding sarcomeric proteins in which the same pathogenic variant affects skeletal and cardiac muscle. Moreover, none of the known genes underlying DA have been found to contain pathogenic variants that also cause cardiac abnormalities. We report five families with DA because of heterozygous missense variants in the gene actin, alpha, cardiac muscle 1 (ACTC1). ACTC1 encodes a highly conserved actin that binds to myosin in cardiac and skeletal muscle. Pathogenic variants in ACTC1 have been found previously to underlie atrial septal defect, dilated cardiomyopathy, hypertrophic cardiomyopathy, and left ventricular noncompaction. Our discovery delineates a new DA condition because of variants in ACTC1 and suggests that some functions of ACTC1 are shared in cardiac and skeletal muscle.


Assuntos
Artrogripose , Cardiomiopatias , Cardiomiopatia Dilatada , Cardiomiopatia Hipertrófica , Cardiopatias Congênitas , Doenças Musculares , Humanos , Artrogripose/genética , Actinas/genética , Cardiopatias Congênitas/complicações , Cardiomiopatias/etiologia , Cardiomiopatia Dilatada/complicações , Doenças Musculares/complicações , Miosinas , Cardiomiopatia Hipertrófica/complicações
4.
medRxiv ; 2023 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-36945405

RESUMO

Contraction of the human sarcomere is the result of interactions between myosin cross-bridges and actin filaments. Pathogenic variants in genes such as MYH7 , TPM1 , and TNNI3 that encode parts of the cardiac sarcomere cause muscle diseases that affect the heart, such as dilated cardiomyopathy and hypertrophic cardiomyopathy. In contrast, pathogenic variants in homologous genes MYH2 , TPM2 , and TNNI2 , that encode parts of the skeletal muscle sarcomere, cause muscle diseases affecting skeletal muscle, such as the distal arthrogryposis (DA) syndromes and skeletal myopathies. To date, there have been few reports of genes (e.g., MYH7 ) encoding sarcomeric proteins in which the same pathogenic variant affects both skeletal and cardiac muscle. Moreover, none of the known genes underlying DA have been found to contain mutations that also cause cardiac abnormalities. We report five families with DA due to heterozygous missense variants in the gene actin, alpha, cardiac muscle 1 ( ACTC1 ). ACTC1 encodes a highly conserved actin that binds to myosin in both cardiac and skeletal muscle. Mutations in ACTC1 have previously been found to underlie atrial septal defect, dilated cardiomyopathy, hypertrophic cardiomyopathy, and left ventricular noncompaction. Our discovery delineates a new DA condition due to mutations in ACTC1 and suggests that some functions of actin, alpha, cardiac muscle 1 are shared in cardiac and skeletal muscle.

5.
Am J Gastroenterol ; 118(7): 1237-1247, 2023 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-36716287

RESUMO

INTRODUCTION: The objective of this study was to assess the durability, short-term and long-term effectiveness, and safety of tofacitinib in ulcerative colitis (UC) in clinical practice. METHODS: This is a retrospective multicenter study including patients with UC who had received the first tofacitinib dose at least 8 weeks before the inclusion. Clinical effectiveness was based on partial Mayo score. RESULTS: A total of 408 patients were included. Of them, 184 (45%) withdrew tofacitinib during follow-up (mean = 18 months). The probability of maintaining tofacitinib was 67% at 6 m, 58% at 12 m, and 49% at 24 m. The main reason for tofacitinib withdrawal was primary nonresponse (44%). Older age at the start of tofacitinib and a higher severity of clinical activity were associated with tofacitinib withdrawal. The proportion of patients in remission was 38% at week 4, 45% at week 8, and 47% at week 16. Having moderate-to-severe vs mild disease activity at baseline and older age at tofacitinib start were associated with a lower and higher likelihood of remission at week 8, respectively. Of 171 patients in remission at week 8, 83 (49%) relapsed. The probability of maintaining response was 66% at 6 m and 54% at 12 m. There were 93 adverse events related to tofacitinib treatment (including 2 pulmonary thromboembolisms [in patients with risk factors] and 2 peripheral vascular thrombosis), and 29 led to tofacitinib discontinuation. DISCUSSION: Tofacitinib is effective in both short-term and long-term in patients with UC. The safety profile is similar to that previously reported.


Assuntos
Colite Ulcerativa , Humanos , Colite Ulcerativa/tratamento farmacológico , Resultado do Tratamento , Indução de Remissão , Estudos Retrospectivos
6.
J Crohns Colitis ; 17(1): 83-91, 2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-35913456

RESUMO

BACKGROUND AND AIMS: Clinical trials and real-life studies with ustekinumab in Crohn's disease [CD] have revealed a good efficacy and safety profile. However, these data are scarcely available in elderly patients. Therefore, we aim to assess the effectiveness and safety of ustekinumab in elderly patients with CD. METHODS: Elderly patients [>60 years old] from the prospectively maintained ENEIDA registry treated with ustekinumab due to CD were included. Every patient was matched with two controls under 60 years of age, according to anti-tumour necrosis factor use and smoking habit. Values for the Harvey-Bradshaw Index [HBI], endoscopic activity, C-reactive protein [CRP] and faecal calprotectin [FC] were recorded at baseline and at weeks 16, 32 and 54. RESULTS: In total, 648 patients were included, 212 of whom were elderly. Effectiveness was similar between young and elderly patients during the follow-up. Steroid-free remission was similar at week 16 [54.6 vs 51.4%, p = 0.20], 32 [53.0% vs 54.5%, p = 0.26] and 54 [57.8% vs 51.1%, p = 0.21]. Persistence of ustekinumab as maintenance therapy was similar in both age groups [log-rank test; p = 0.91]. There was no difference in the rate of adverse effects [14.2% vs 11.2%, p = 0.350], including severe infections [7.1% vs 7.3%, p = 1.00], except for the occurrence of de novo neoplasms, which was higher in older patients [0.7% vs 4.3%, p = 0.003]. CONCLUSIONS: Ustekinumab is as effective in elderly patients with CD as it is in non-elderly patients. The safety profile also seems to be similar except for a higher rate of de novo neoplasms, probably related to the age of the elderly patients.


Assuntos
Doença de Crohn , Ustekinumab , Humanos , Pessoa de Meia-Idade , Idoso , Ustekinumab/efeitos adversos , Doença de Crohn/patologia , Indução de Remissão , Endoscopia , Sistema de Registros , Resultado do Tratamento , Estudos Retrospectivos
7.
Nutrients ; 13(6)2021 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-34067320

RESUMO

Iron deficiency anemia (IDA) is a common manifestation of Inflammatory Bowel Disease (IBD). Oral iron supplements are the treatment of choice, but are not always well tolerated. Sucrosomial® iron (SI) may represent an alternative. This prospective study assessed the tolerability and effectiveness of SI, and quality of life (QoL) of IDA-IBD patients who were intolerant to oral iron salts. The study included 52 individuals treated with 1 capsule/day for 12 weeks. Tolerability was assessed through a gastrointestinal symptom severity questionnaire. Hemoglobin (Hb) levels and clinical symptoms of IDA were analyzed. QoL was assessed using IBDQ-9 and EuroQoL questionnaires. The percentage of patients with excellent/good health increased from 42.9% to 94.3%. Mean Hb concentration significantly increased at all follow-up visits (p < 0.05). Almost all participants (96.9%) were adherent to the study medication. Patients' QoL improved (IBDQ-9: from 60.9 to 65.5). Patients also improved in mobility (71.8% to 78.1%), usual activities (51.3% to 68.7%), pain/discomfort (41.0% to 53.1%), and extreme depression/anxiety problems (7.7% to 3.2%); they worsened in self-care (100% to 90.6%), but perceived an enhancement in their global health [EQ-VAS score: 61.9 (±26.1) to 66.9 (±20.3)]. SI was well tolerated and improved IDA symptoms, IBD activity, and patients' QoL. In conclusion, SI should be considered in IDA-IBD patients.


Assuntos
Anemia Ferropriva/tratamento farmacológico , Doenças Inflamatórias Intestinais/tratamento farmacológico , Ferro/administração & dosagem , Qualidade de Vida , Administração Oral , Adulto , Idoso , Idoso de 80 Anos ou mais , Anemia Ferropriva/complicações , Suplementos Nutricionais , Feminino , Compostos Férricos , Hemoglobinas/análise , Humanos , Doenças Inflamatórias Intestinais/complicações , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Inquéritos e Questionários , Oligoelementos/administração & dosagem , Resultado do Tratamento , Adulto Jovem
8.
Mol Genet Genomic Med ; 9(5): e1649, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33733630

RESUMO

OBJECTIVE: Prenatal diagnoses of microdeletion syndromes without ultrasound findings in the first and second trimester are always difficult. The objective of this study is to report the prenatal ultrasound findings in four foetuses diagnosed with 17q21.31 microdeletions (Koolen-de Vries syndrome) using chromosomal microarrays (CMA). PATIENTS AND METHODS: We present four foetuses with 17q21.31 microdeletion. All showed CNS anomalies in the third trimester, three had ventriculomegaly, and one hypogenesis of corpus callosum at 31 weeks of pregnancy. RESULTS: Array-SNPs and CGH-array were performed on uncultured amniocytes and peripheral blood revealing a 17q21.31 microdeletion. CONCLUSIONS: Prenatal CNS anomalies (mainly ventriculomegaly) at third trimester, in spite of isolate, should be considered a prenatal ultrasound marker of this syndrome. This kind of malformations raise the possibility of an underlying genetic conditions including 17q21.31 microdeletion; thus, CMA should be taken into consideration when offering prenatal genetic counselling.


Assuntos
Anormalidades Múltiplas/diagnóstico por imagem , Ventrículos Cerebrais/diagnóstico por imagem , Corpo Caloso/diagnóstico por imagem , Testes Genéticos , Deficiência Intelectual/diagnóstico por imagem , Ultrassonografia Pré-Natal , Anormalidades Múltiplas/genética , Anormalidades Múltiplas/patologia , Adulto , Ventrículos Cerebrais/embriologia , Deleção Cromossômica , Cromossomos Humanos Par 17/genética , Corpo Caloso/embriologia , Feminino , Humanos , Recém-Nascido , Deficiência Intelectual/genética , Deficiência Intelectual/patologia , Masculino , Gravidez
9.
Gastroenterol Hepatol ; 43(3): 126-132, 2020 Mar.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-31866167

RESUMO

INTRODUCTION: Ustekinumab, a monoclonal antibody that blocks interleukins 12/23, has proven in clinical trials its efficacy in inducing and maintaining clinical remission of Crohn's disease (CD). Its effectiveness and safety in actual clinical practice is less known and may differ from trials. OBJECTIVE: To evaluate its effectiveness and safety in clinical practice (intravenous induction pattern essentially), such as induction and over the long term, in patients with CD refractory to biological treatment. MATERIAL AND METHODS: Multicentre retrospective analysis (6 hospitals in Aragón), which includes all patients (N=69) with CD undergoing treatment with ustekinumab (either with intravenous or subcutaneous induction), who had at least 16 weeks of follow-up. The clinical response or remission has been evaluated at weeks 16, 24, 32 and 48 using the Harvey-Bradshaw index. RESULTS: A total of 69 patients have been included, mean age 42 years, 54% men. A percentage of 89.86 (95% CI [0.805, 0.949]) of the patients presented clinical improvement at week 16 (15.95% remission, 73.92% response). In the subsequent follow-up, this response has been maintained. Age (OR 0.95, P=.028) and smoking habits (OR 0.19, P=.027) have been identified by an ordinal regression model as predictors of poor treatment response while the need for biological change due to adverse effect (OR 96, P=.00017) and due to loss of secondary response (OR 7.07, P=.034) have been predictors of good response. No serious adverse effects have been reported that forced them to stop taking ustekinumab. CONCLUSION: Ustekinumab is effective and safe in real clinical practice to achieve induction and maintenance of the response in patients with refractory CD. Tobacco and age have been shown to be predictors of poor response, while the indication for adverse effect to previous biological and for loss of secondary response has been shown to be predictors of good response.


Assuntos
Doença de Crohn/tratamento farmacológico , Ustekinumab/uso terapêutico , Corticosteroides/uso terapêutico , Adulto , Substituição de Medicamentos , Quimioterapia Combinada , Feminino , Humanos , Imunossupressores/uso terapêutico , Masculino , Pessoa de Meia-Idade , Indução de Remissão , Estudos Retrospectivos , Fatores de Risco , Índice de Gravidade de Doença , Fumar/epidemiologia , Resultado do Tratamento , Ustekinumab/efeitos adversos
10.
Gastroenterol Hepatol ; 40(10): 651-657, 2017 Dec.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-28941945

RESUMO

BACKGROUND: Rapid Urease Test (RUT) is a simple, cheap and relatively fast method for diagnosing Helicobacter pylori infection. It is therefore the preferred method used for patients undergoing gastroscopy. Most kits require 24h to give results. The new Ultra-Rapid Urease Test (URUT) kit by Biohit® requires less than 1h. OBJECTIVE: To determine URUT's diagnostic accuracy. METHOD: Prospective, blind, multi-centre study involving dyspeptic patients. One corpus biopsy and three antral biopsies were obtained during gastroscopy for standard histological analysis, RUT and URUT. The URUT result was checked after 1min, 5min, 30min and 60min and the RUT was checked over the course of 24h. Histology was used as the gold standard test. RESULTS: 144 patients were included, 68% female, with a mean age of 49 years old; 50% were H. pylori positive. RUT and URUT diagnoses were correct in 85.9% and 90% of the cases, respectively. The mean waiting time for a positive RUT result was 6h. The sensitivity, specificity, and positive and negative predictive values for RUT were, respectively, 82%, 90%, 89% and 84%. The URUT's results were similar (85%, 94%, 94% and 87%). These figures improved when patients taking PPIs were excluded (RUT: 86%, 91%, 93% and 83%; URUT: 91%, 94%, 96% and 89%). No statistically significant differences were found when comparing RUT and URUT distributions of correct diagnoses (McNemar's Test, p=0.3) but there was a tendency towards better results with the URUT. CONCLUSION: The URUT is equivalent to (or slightly better than) the traditional RUT in diagnosing H. pylori infection, and provides results in less than an hour.


Assuntos
Ensaios Enzimáticos Clínicos , Infecções por Helicobacter/diagnóstico , Helicobacter pylori/enzimologia , Urease/análise , Biópsia , Feminino , Gastroscopia , Infecções por Helicobacter/microbiologia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Reprodutibilidade dos Testes
11.
J Crohns Colitis ; 9(12): 1063-70, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26351379

RESUMO

BACKGROUND AND AIMS: Patients with ulcerative colitis (UC) are at increased risk of developing colorectal cancer (CRC), but recent studies suggest a lower risk than previously reported. The aim was to evaluate the incidence of dysplasia, CRC and related risk factors in UC patients from a Spanish nationwide database. METHODS: All UC patients were identified and retrospectively reviewed. Clinical-epidemiological data and the finding of dysplasia and/or CRC were collected. RESULTS: A total of 831 UC patients were included. Twenty-six cases of CRC in 26 patients and 29 cases of high-grade dysplasia (HGD) in 24 patients were found, accounting for 55 diagnoses of advanced neoplasia (AN = CRC and/or HGD) in 45 patients (33% of them within the first 8 years after UC diagnosis). The cumulative risk of AN was 2, 5.3 and 14.7% at 10, 20 and 30 years, respectively. Concomitant primary sclerosing cholangitis (odds ratio [OR] 10.90; 95% confidence interval [CI] 3.75-31.76, p < 0.001), extensive UC (OR 2.10, 95% CI 1.01-4.38, p = 0.048), UC diagnosis at an older age (OR 2.23, 95% CI 1.03-4.83, p = 0.043) and appendectomy prior to UC diagnosis (OR 2.66, 95% CI 1.06-6.71, p = 0.038) were independent risk factors for AN. Use of thiopurines (OR 0.21, 95% CI 0.06-0.74, p = 0.015) and being in a surveillance colonoscopy programme (OR 0.33; 95% CI 0.16-0.67; p = 0.002) were independent protective factors for AN. CONCLUSIONS: The risk of AN among UC patients is lower than previously reported but steadily increases from the time of UC diagnosis. The widespread use of thiopurines may have influenced this reduced incidence of UC-related neoplasias.


Assuntos
Colite Ulcerativa/tratamento farmacológico , Neoplasias Colorretais/etiologia , Imunossupressores/uso terapêutico , Mercaptopurina/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Colite Ulcerativa/complicações , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/prevenção & controle , Feminino , Seguimentos , Humanos , Incidência , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , Espanha
12.
Biomed Res Int ; 2014: 548729, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25101287

RESUMO

INTRODUCTION: The value of a single umbilical artery (SUA) in first trimester ultrasound is not well established. The aim of our study was to determinate the relevance of diagnosis of single umbilical artery in first trimester ultrasound as an early marker suggesting the presence of malformations or associated chromosomopathies. MATERIAL AND METHODS: Retrospective study of clinical cases of SUA diagnosed at the University Hospital Puerta de Hierro in Madrid (Spain) during the first trimester ultrasound between September 2008 and September 2012. RESULTS: Prevalence of SUA was 1.1% in single pregnancies and 3.3% in twin pregnancies. Sensitivity, specificity, false positive rate, and false negative rate for the finding in the first trimester were 84.2, 99.8, 0.2, and 15.7%, respectively. 17.6% of cases had associated malformations. With an ultrasound in the 16th week most of the cases with significant fetal malformation were diagnosed. DISCUSSION: SUA is a useful marker in the first trimester for fetal malformation pathology, as it will allow detecting a large number of cases with malformations before 20 weeks of gestation.


Assuntos
Anormalidades Congênitas/diagnóstico por imagem , Artéria Umbilical Única/diagnóstico por imagem , Ultrassonografia Pré-Natal/métodos , Transtornos Cromossômicos/diagnóstico , Transtornos Cromossômicos/patologia , Anormalidades Congênitas/diagnóstico , Anormalidades Congênitas/patologia , Feminino , Feto/patologia , Humanos , Gravidez , Primeiro Trimestre da Gravidez , Estudos Retrospectivos , Artéria Umbilical Única/patologia
13.
Chemistry ; 8(1): 171-6, 2002 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-11822448

RESUMO

Phenol tri- and nonaallyl dendrons (3 and 7, respectively) were functionalized at the focal position to give the new triallyl dendrons 4 and 6 and the nonaallyl dendrons 11 and 13 that contain a iodoalkyl or a bromobenzyl termini. All these dendrons were used for the [FeCp]+-induced hexafunctionalization of hexamethylbenzene in [FeCp(eta6-C6Me6)][PF6] (1) under mild conditions in the presence of KOH. These reactions directly yielded the 18-allyl and 54-allyl dendrimers 9, 10, and 14 with a [FeCp(eta6-arene)]+ unit located at the dendrimer core. Cyclic voltammetry studies were recorded in THF and DMF with these metallodendrimers and compared with those of analogous dendrimers or complexes of smaller size that contain a [FeCp(eta6-arene)]+ unit at the core. The decreased rate of heterogeneous electron transfer when the dendritic size increases first disclosed by Diederich and Gross is confirmed. The variation of the redox potential of the Fe(II/I) redox system with increasing dendritic size is negligible even in a solvent of high dielectric constant such as DMF. This trend is attributed to fact that the involved "redox" orbital is buried on the metal center, well protected by the shell of alkyl chains (electron-reservoir nature), unlike in ferrocene. The chemical irreversibility increases in THF as the dendrimer size increases, due to more facile ligand substitution with THF at the 19-electron level when the chain bulk increases.

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