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1.
Phys Rev Lett ; 129(17): 172701, 2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36332266

RESUMO

The ß-delayed one- and two-neutron emission probabilities (P_{1n} and P_{2n}) of 20 neutron-rich nuclei with N≥82 have been measured at the RIBF facility of the RIKEN Nishina Center. P_{1n} of ^{130,131}Ag, ^{133,134}Cd, ^{135,136}In, and ^{138,139}Sn were determined for the first time, and stringent upper limits were placed on P_{2n} for nearly all cases. ß-delayed two-neutron emission (ß2n) was unambiguously identified in ^{133}Cd and ^{135,136}In, and their P_{2n} were measured. Weak ß2n was also detected from ^{137,138}Sn. Our results highlight the effect of the N=82 and Z=50 shell closures on ß-delayed neutron emission probability and provide stringent benchmarks for newly developed macroscopic-microscopic and self-consistent global models with the inclusion of a statistical treatment of neutron and γ emission. The impact of our measurements on r-process nucleosynthesis was studied in a neutron star merger scenario. Our P_{1n} and P_{2n} have a direct impact on the odd-even staggering of the final abundance, improving the agreement between calculated and observed Solar System abundances. The odd isotope fraction of Ba in r-process-enhanced (r-II) stars is also better reproduced using our new data.

2.
Phys Rev Lett ; 124(25): 252701, 2020 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-32639776

RESUMO

The prediction of stellar (γ,α) reaction rates for heavy nuclei is based on the calculation of (α,γ) cross sections at sub-Coulomb energies. These rates are essential for modeling the nucleosynthesis of so-called p nuclei. The standard calculations in the statistical model show a dramatic sensitivity to the chosen α-nucleus potential. The present study explains the reason for this dramatic sensitivity which results from the tail of the imaginary α-nucleus potential in the underlying optical model calculation of the total reaction cross section. As an alternative to the optical model, a simple barrier transmission model is suggested. It is shown that this simple model in combination with a well-chosen α-nucleus potential is able to predict total α-induced reaction cross sections for a wide range of heavy target nuclei above A≳150 with uncertainties below a factor of 2. The new predictions from the simple model do not require any adjustment of parameters to experimental reaction cross sections whereas in previous statistical model calculations all predictions remained very uncertain because the parameters of the α-nucleus potential had to be adjusted to experimental data. The new model allows us to predict the reaction rate of the astrophysically important ^{176}W(α,γ)^{180}Os reaction with reduced uncertainties, leading to a significantly lower reaction rate at low temperatures. The new approach could also be validated for a broad range of target nuclei from A≈60 up to A≳200.

3.
Phys Rev Lett ; 117(16): 162501, 2016 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-27792367

RESUMO

In an experiment with the BigRIPS separator at the RIKEN Nishina Center, we observed two-proton (2p) emission from ^{67}Kr. At the same time, no evidence for 2p emission of ^{59}Ge and ^{63}Se, two other potential candidates for this exotic radioactivity, could be observed. This observation is in line with Q value predictions which pointed to ^{67}Kr as being the best new candidate among the three for two-proton radioactivity. ^{67}Kr is only the fourth 2p ground-state emitter to be observed with a half-life of the order of a few milliseconds. The decay energy was determined to be 1690(17) keV, the 2p emission branching ratio is 37(14)%, and the half-life of ^{67}Kr is 7.4(30) ms.

4.
J Phys Chem A ; 120(47): 9411-9421, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27934332

RESUMO

The dissociative ionization (multiphoton regime) of the D2+ ion by ultrashort laser pulses has been studied theoretically using ab initio calculations. The combined ionization and dissociation spectrum was explored for fixed molecular axis orientations. In accordance with previous investigations, the dominant features in the obtained joint energy spectrum were multiphoton peaks. In addition to this, in the present work, photoelectron angular distributions were analyzed as well. By performing a partial wave analysis for each multiphoton peak, we have identified the number of absorbed photons. Moreover, we also found that the angular distribution can significantly change inside a multiphoton peak as a function of electron and nuclear kinetic energy.

5.
Phys Rev Lett ; 109(23): 232701, 2012 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-23368189

RESUMO

The (13)C(α,n)(16)O reaction is the neutron source for the main component of the s-process, responsible for the production of most nuclei in the mass range 90

6.
Sci Rep ; 12(1): 3932, 2022 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-35273213

RESUMO

Due to the highly increased interest in the development of state-of-the-art applications of photoemission in ultrafast electron microscopy, development of photocathodes and many more applications, a correct theoretical understanding of the underlying phenomena is needed. Within the framework of the single active electron approximation the most accurate results can be obtained by the direct solution of the time-dependent Schrödinger equation (TDSE). In this work, after a brief presentation of a numerically improved version of a mixed 1D-TDSE method, we investigated the characteristics of electron spectra obtained from the surface of metal nanoparticles irradiated with ultrashort laser pulses. During our investigation different decay lengths of the plasmonic-enhanced incident field in the vicinity of the metal were considered. Using the simulated spectra we managed to identify the behavior of the cutoff energy as a function of decay length in the strong-field, multiphoton and transition regimes.

7.
Urologe A ; 59(1): 65-71, 2020 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-31741004

RESUMO

Due to a safety alert issued by the US Food and Drug Administration (FDA) in 2011 for transvaginal mesh implants to treat female prolapse as a result of numerous reports of complications such as infection, chronic pain, dyspareunia, vaginal erosion, shrinkage and erosion into other organs nearly all industrial products have been withdrawn from the market in the meantime. The United Kingdom, Australia, and New Zealand extended warnings and prohibitions even on the implantation of midurethral slings (TVT, TOT). In view of these current international controversies regarding the use of implanted materials for the treatment of stress incontinence and prolapse and the lack of clear guidelines for the use of biomaterials, the opinion of the Working Group on Urological Functional Diagnostics and Female Urology should provide clarity. The Opinion is based on the SCENIHR Report of the "European Commission's Scientific Committee on Emerging and Newly Identified Health Risks", the "Consensus Statement of the European Urology Association and the European Urogynaecological Association on the Use of Implanted Materials for Treating Pelvic Organ Prolapse and Stress Urinary Incontinence" and in compliance with relevant EAU and national guidelines and the opinion of the Association for Urogynaecology and Plastic Pelvic Floor Reconstruction (AGUB eV). In addition, recommendations are given for the future handling of implants of slings and meshes for the treatment of stress incontinence and prolapse from a urologic viewpoint.


Assuntos
Prolapso de Órgão Pélvico/cirurgia , Slings Suburetrais/efeitos adversos , Telas Cirúrgicas/efeitos adversos , Incontinência Urinária por Estresse/cirurgia , Procedimentos Cirúrgicos Urológicos/instrumentação , Feminino , Alemanha , Humanos
8.
J Cell Biol ; 77(1): 246-63, 1978 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-659512

RESUMO

Mutant lines of mouse L cells, TS A1S9, and TS C1, show temperature-sensitive (TS) DNA synthesis and cell division when shifted from 34 degrees to 38.5 degrees C. With TS A1S9 the decline in DNA synthesis begins after 6-8 h at 38.5 degrees C and is most marked at about 24 h. Most cells in S, G2, or M at temperature upshift complete one mitosis and accumulate in the subsequent interphase at G1 or early S as a result of expression of a primary defect, failure of elongation of newly made small DNA fragments. Heat inactivation of TS C1 cells is more rapid; they fail to complete the interphase in progress at temperature upshift and accumulate at late S or G2. Inhibition of both cell types is reversible on return to 34 degrees C. Cell and nuclear growth continues during inhibition of replication. Expression of both TS mutations leads to a marked change in gross organization of chromatin as revealed by electron microscopy. Nuclei of wild-type cells at 34 degrees and 38.5 degrees C and mutant cells at 34 degrees C show a range of aggregation of condensed chromatin from small dispersed bodies to large discrete clumps, with the majority in an intermediate state. In TS cells at 38.5 degrees C, condensed chromatin bodies in the central nuclear region become disaggregated into small clumps dispersed through the nucleus. Morphometric estimation of volume of condensed chromatin indicates that this process is not due to complete decondensation of chromatin fibrils, but rather involves dispersal of large condensed chromatin bodies into finer aggregates and loosening of fibrils within the aggregates. The dispersed condition is reversed in nuclei which resume DNA synthesis when TS cells are downshifted from 38.5 degrees to 34 degrees C. The morphological observations are consistent with the hypothesis that condensed chromatin normally undergoes an ordered cycle of transient, localized disaggregation and reaggregation associated with replication. In temperature-inactivated mutants, normal progressive disaggregation presumably occurs, but subsequent lack of chromatin replication prevents reaggregation.


Assuntos
Ciclo Celular , Cromatina/ultraestrutura , Interfase , Contagem de Células , Divisão Celular , Núcleo Celular/ultraestrutura , DNA/biossíntese , Células L , Mutação , Temperatura
9.
J Cell Biol ; 106(3): 597-607, 1988 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2450096

RESUMO

To identify bacterial genes involved in symbiotic nodule development, ineffective nodules of alfalfa (Medicago sativa) induced by 64 different Fix-mutants of Rhizobium meliloti were characterized by assaying for symbiotic gene expression and by morphological studies. The expression of leghemoglobin and nodulin-25 genes from alfalfa and of the nifHD genes from R. meliloti were monitored by hybridizing the appropriate DNA probes to RNA samples prepared from nodules. The mutants were accordingly divided into three groups. In group I none of the genes were expressed, in group II only the plant genes were expressed and in group III all three genes were transcribed. Light and electron microscopical analysis of nodules revealed that nodule development was halted at different stages in nodules induced by different group I mutants. In most cases nodules were empty lacking infection threads and bacteroids or nodules contained infection threads and a few released bacteroids. In nodules induced by a third mutant class bacteria were released into the host cells, however the formation of the peribacteroid membrane was not normal. On this basis we suggest that peribacteroid membrane formation precedes leghemoglobin and nodulin-25 induction, moreover, after induction of nodulation by the nod genes at least two communication steps between the bacteria and the host plants are necessary for the development of the mature nodule. By complementing each mutant of group I with a genomic R. meliloti library made in pLAFRl, four new fix loci were identified, indicating that several bacterial genes are involved in late nodule development.


Assuntos
Regulação da Expressão Gênica , Genes Bacterianos , Proteínas de Membrana , Fixação de Nitrogênio/genética , Proteínas de Plantas/genética , Rhizobium/genética , Teste de Complementação Genética , Leghemoglobina/genética , Medicago sativa , Microscopia Eletrônica , Mutação , Hibridização de Ácido Nucleico , RNA Bacteriano/análise , Rhizobium/ultraestrutura , Simbiose
11.
Appl Radiat Isot ; 148: 87-90, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30925368

RESUMO

The literature half-life value of 65Ga is based on only one experiment carried out more than 60 years ago and it has a relatively large uncertainty. In the present work this half-life is determined based on the counting of the γ-rays following the ß-decay of 65Ga. Our new recommended half-life is t1/2 = (15.133 ±â€¯0.028) min which is in agreement with the literature value but almost one order of magnitude more precise.

13.
Transplant Proc ; 50(3): 769-771, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29661434

RESUMO

BACKGROUND: Treatment with direct-acting antiviral drugs in interferon-free regimens is currently recommended for viral hepatitis C recurrence after liver transplantation. There are limited data regarding its results in this population, and no optimal treatment scheme has yet been singled out. METHODS: We report our real-world results in liver transplant (LT) recipients. All patients were hepatitis C virus (HCV) monoinfected and completed a 12-week treatment course, followed 12 weeks later by HCV polymerase chain reaction testing with 12 IU/mL sensibility. Liver fibrosis was graded with the use of biopsies taken <12 months before treatment and stratified as early (0-1) or moderate to advanced (2-4) according to the Metavir score. RESULTS: Median postoperative time was 5.2 years. Genotype 3 was found in 66.7% of the sample. The following regimens were prescribed: daclatasvir-sofosbuvir with (n = 11) or without (n = 28) ribavirin. Genotypes 1 and 3 were evenly distributed between the regimens. Sustained virologic response (SVR) was obtained in 24 out of 28 patients (85.7%) who received daclatasvir-sofosbuvir and in all patients (100%) who received daclatasvir-sofosbuvir-ribavirin (global SVR 89.7%). All patients that failed treatment had genotype 3 HCV. Fibrosis was evaluated in 79.5% of the sample: 48.4% had early and 51.6% had moderate to advanced fibrosis, for which ribavirin was more commonly prescribed (P = .001). CONCLUSIONS: The SVR rate in our LT recipients was similar to that previously reported in the literature. The addition of ribavirin to DAA treatment appears to be justified in this population.


Assuntos
Antivirais/administração & dosagem , Hepatite C/tratamento farmacológico , Imidazóis/administração & dosagem , Transplante de Fígado/efeitos adversos , Complicações Pós-Operatórias/tratamento farmacológico , Ribavirina/administração & dosagem , Sofosbuvir/administração & dosagem , Idoso , Carbamatos , Quimioterapia Combinada , Feminino , Genótipo , Hepacivirus/genética , Hepatite C/virologia , Humanos , Cirrose Hepática/virologia , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/virologia , Pirrolidinas , Recidiva , Resposta Viral Sustentada , Resultado do Tratamento , Valina/análogos & derivados
14.
Mol Cell Biol ; 1(6): 535-43, 1981 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-6765606

RESUMO

Plasmids containing the nontranscribed central and terminal, but not the coding, regions of the extrachromosomal ribosomal deoxyribonucleic acid (rDNA) of Tetrahymena thermophila are capable of autonomous replication in Saccharomyces cerevisiae. These plasmids transform S. cerevisiae at high frequency; transformants are unstable in the absence of selection, and plasmids identical to those used for transformation were isolated from the transformed yeast cells. One plasmid contains a 1.85-kilobase Tetrahymena DNA fragment which includes the origin of bidirectional replication of the extrachromosomal rDNA. The other region of Tetrahymena rDNA allowing autonomous replication of plasmids in S. cerevisiae is a 650-base pair, adenine plus thymine-rich segment from the rDNA terminus. Neither of these Tetrahymena fragments shares obvious sequence homology with the origin of replication of the S. cerevisiae 2-microns circle plasmid or with ars1, an S. cerevisiae chromosomal replicator.


Assuntos
DNA Ribossômico/genética , Plasmídeos , Saccharomyces cerevisiae/genética , Tetrahymena/genética , Animais , Sequência de Bases , Clonagem Molecular , Replicação do DNA , Dados de Sequência Molecular
15.
Urologe A ; 46(6): 662-6, 2007 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-17356837

RESUMO

BACKGROUND: The effectiveness of intravesical electrostimulation (IVES) in the treatment of acute prolonged bladder overdistension (PBO) was investigated. METHODS: Sixteen patients (female 11, male 5, ø 54 years) after PBO (bladder filling volume: 1317+/-320 ml) were evaluated: 11 after surgery and 5 after polytrauma, psychosomatic disorder or LV4 fracture. After exclusion of a neurogenic aetiology and a urodynamic examination, IVES was performed besides IC or suprapubic catheter. RESULTS: Group 1: six patients with a weak detrusor (p(detr. max.)<30 cmH(2)O); group 2: ten patients had detrusor acontractility. After 25 IVES sessions, group 1 showed a significant increase of p(detr. max.) (p=0.01) as well as a decrease in PVR (31% to 3% of bladder capacity, p=0.02). Group 2 had no significant increase of p(detr. max). CONCLUSIONS: Two-thirds of patients with a weak detrusor after PBO will regain balanced voiding after IVES due to detrusor reinforcement. With an acontractile detrusor only bladder sensation improves.


Assuntos
Terapia por Estimulação Elétrica/instrumentação , Retenção Urinária/reabilitação , Urodinâmica/fisiologia , Doença Aguda , Adulto , Idoso , Eletrodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Hipotonia Muscular/etiologia , Hipotonia Muscular/fisiopatologia , Hipotonia Muscular/reabilitação , Retratamento , Bexiga Urinária/fisiopatologia , Retenção Urinária/etiologia , Retenção Urinária/fisiopatologia
16.
Transplant Proc ; 49(7): 1530-1534, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28838434

RESUMO

INTRODUCTION: Post-transplantation portal hypertension has severe complications, such as esophageal varix bleeding, therapy refractory ascites, extreme splenomegaly, and graft dysfunction. The aim of our study was to analyze the effectiveness of the therapeutic strategies and how to visualize the procedure. METHODS: A retrospective study involving liver transplantation patients from the Semmelweis University Department of Transplantation and Surgery was performed between 2005 and 2015. The prevalence, etiology, and leading complications of the condition were determined. The applied interventions' effects on the patients' ascites volume, splenic volume, and the occurrence of variceal bleeding were determined. Mean portal blood flow velocity and congestion index values were calculated using Doppler ultrasonography. RESULTS: The prevalence of post-transplantation portal hypertension requiring intervention was 2.8%. The most common etiology of the disease was portal anastomotic stenosis. The most common complications were esophageal varix bleeding and therapy refractory ascites. The patients' ascites volume decreased significantly (2923.3 ± 1893.2 mL vs. 423.3 ± 634.3 mL; P < .05), their splenic volume decreased markedly. After the interventions, only one case of recurrent variceal bleeding was reported. The calculated Doppler parameters were altered in the opposite direction in cases of pre-hepatic versus intra- or post-hepatic portal hypertension. After the interventions, these parameters shifted towards the physiologic ranges. CONCLUSION: The interventions performed in our clinic were effective in most cases. The patients' ascites volume, splenic volume, and the prevalence of variceal bleeding decreased after the treatment. Doppler ultrasonography has proved to be a valuable imaging modality in the diagnosis and the follow-up of post-transplantation portal hypertension.


Assuntos
Gerenciamento Clínico , Hipertensão Portal/cirurgia , Transplante de Fígado/efeitos adversos , Veia Porta/cirurgia , Complicações Pós-Operatórias/cirurgia , Adulto , Idoso , Anastomose Cirúrgica/efeitos adversos , Ascite/etiologia , Ascite/cirurgia , Constrição Patológica/etiologia , Constrição Patológica/cirurgia , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/cirurgia , Feminino , Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/cirurgia , Humanos , Hipertensão Portal/etiologia , Masculino , Pessoa de Meia-Idade , Veia Porta/patologia , Complicações Pós-Operatórias/etiologia , Prevalência , Estudos Retrospectivos , Resultado do Tratamento
17.
Transplant Proc ; 38(6): 1872-5, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16908310

RESUMO

University of Wisconsin (UW) solution has been the standard for preservation of liver transplantation grafts since 1989. However, some studies demonstrated that histidine-tryptophan-ketoglutarate (HTK) solution is also effective. The purpose of this study was to compare the efficacy of both solutions in liver transplantation. From January 2003 to August 2004 the livers of deceased donors were randomized into HTK and UW groups. The 102 studied patients included 65 (63.7%) in the UW group and 37 (36.3%) in the HTK group. Sex, race, hemodynamic state, use of adrenergic drugs, and presence of steatosis in the donor were similarly distributed in the two groups (P > .05). The mean age of the donors was 38.1 years (SD +/-14.4) in the UW group and 44.6 years (SD +/-14.2) in the HTK cohort (P = .036). Sex, race, age, etiology of the cirrhosis, retransplant, acute liver failure, portal thrombosis, and Child-Pugh and MELD scores in the recipients were similarly distributed in the two recipient samples (P > .05). Among 89 patients who completed 4 months of follow-up, the HTK group included eight cases (25.8%) of biliary complications versus five cases (8.6%) in the UW group (P = .033; OR = 2.0 95% CI = 1.2-3.5). The incidence of graft dysfunction was 2.8% in the HTK group and 9.4% in the UW group (P = .15). In conclusion, UW and HTK solutions were equally effective for the preservation of the hepatic graft. The routine use of HTK solution can reduce the costs of liver transplantation.


Assuntos
Transplante de Fígado/fisiologia , Fígado , Soluções para Preservação de Órgãos , Preservação de Órgãos/métodos , Adenosina , Adulto , Alopurinol , Feminino , Glutationa , Sobrevivência de Enxerto , Histidina , Humanos , Insulina , Hepatopatias/classificação , Hepatopatias/cirurgia , Transplante de Fígado/mortalidade , Masculino , Pessoa de Meia-Idade , Rafinose , Taxa de Sobrevida , Resultado do Tratamento , Triptofano
18.
Ann Fr Anesth Reanim ; 25(9): 1000-2, 2006 Sep.
Artigo em Francês | MEDLINE | ID: mdl-16891086

RESUMO

If the cardiac injuries are frequent after closed chest traumatism, the cardiac injuries after abdominal closed traumatism are unusual but serious. We report the case of a right auricular rupture associated with a liver injury after a closed abdominal traumatism. The diagnosis was suspected on the TDM and confirmed by echocardiography. An emergency sternotomy was performed due to sudden haemodynamic instability. The initial clinical signs are often misleading. However the diagnosis must be made quickly and the treatment begun without delay.


Assuntos
Átrios do Coração , Ruptura Cardíaca , Ferimentos não Penetrantes/complicações , Traumatismos Abdominais/etiologia , Acidentes de Trânsito , Adulto , Ecocardiografia , Feminino , Ruptura Cardíaca/diagnóstico por imagem , Ruptura Cardíaca/cirurgia , Humanos , Fígado/lesões , Esterno/cirurgia , Ferimentos não Penetrantes/diagnóstico por imagem
19.
Transplant Proc ; 48(7): 2544-2547, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27742344

RESUMO

BACKGROUND: Contrast-enhanced ultrasound combines the advantages of native ultrasound and other contrast-enhanced imaging modalities. In selected cases it can be preferable to computerized tomographic scan among kidney transplant recipients. METHODS: We performed a retrospective study involving patients of Semmelweis University Department of Transplantation and Surgery who underwent contrast-enhanced ultrasound examination from 2011 to 2015. During this period, 251 examinations were performed, including 45 on kidney transplant patients. A Toshiba Aplio XU ultrasound device was used, and 1-1.5 mL contrast agent (Sonovue) was administered intravenously for each patient. The indications of these evaluations can be divided into 3 groups: characterization of circumscribed kidney lesions, control after radiofrequency ablation therapy, and examination of graft perfusion. RESULTS: Fully 93% of the examinations were conclusive. In the 1st group of the 37 cases where tumor-suspect lesions were investigated, 13 examinations suggested the presence of a space-occupying lesion. Of those 13 cases, 2 patients had a negative biopsy, nephrectomy was performed in 11 cases, and histologic evaluation verified a tumor in 8 samples. In the 2nd group, the ablation control examination detected a residual tumor in none of the 6 cases. Finally, in 1 of the 2 grafts where the circulation was investigated, blood flow was satisfactory, and in the other it was low. CONCLUSIONS: The contrast-enhanced ultrasound examination was conclusive in most cases. The applied contrast material is not nephrotoxic, and the method uses nonionizing radiation. These features make contrast-enhanced ultrasound highly suitable for the examination of kidney transplant patients.


Assuntos
Transplante de Rim , Rim/diagnóstico por imagem , Ultrassonografia/métodos , Adulto , Idoso , Meios de Contraste , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Fosfolipídeos , Estudos Retrospectivos , Hexafluoreto de Enxofre
20.
Int J Pediatr Otorhinolaryngol ; 91: 86-89, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27863648

RESUMO

OBJECTIVE: The solution of severe tracheobronchial obstructions in early childhood means a great challenge. Biodegradable stents were intended to be a minimally invasive temporary solution which may decrease the number of interventions and limit the possible complications of stenting procedures. However, our first experiences have brought out a new, - especially in childhood - potentially life-threatening complication of this concept. METHODS: Five SX-ELLA biodegradable polydioxanone stents was applied in three patients because of severe tracheobronchial obstruction: congenital tracheomalacia (7 day-old), acquired tracheomalacia (10 month-old), and congenital trachea-bronchomalacia (10 month-old). RESULTS: The breathing of all children improved right after the procedure. We observed degradation of the stent from the 5th postoperative week which resulted in large intraluminar fragments causing significant airway obstruction: one patient died of severe pneumonia, the other baby required urgent bronchoscopy to remove the obstructing 'foreign body' from the trachea. In the third case repeated stent placements successfully maintained the tracheal lumen. CONCLUSIONS: Polydioxanone stents may offer an alternative to metallic or silastic stents for collapse or external compression of the trachea in children; however, large decaying fragments mean a potential risk especially in the small size pediatric airway. The fragmentation of the stent, which generally starts in the 4-6 postoperative weeks, may create large sharp pieces. These may be anchored to the mucosa and covered by crust leading to obstruction. As repeated interventions are required, we do not consider the application of biodegradable stents unambiguously advantageous.


Assuntos
Implantes Absorvíveis/efeitos adversos , Obstrução das Vias Respiratórias/etiologia , Corpos Estranhos/etiologia , Stents/efeitos adversos , Traqueia , Obstrução das Vias Respiratórias/cirurgia , Broncomalácia/terapia , Broncoscopia , Feminino , Corpos Estranhos/cirurgia , Humanos , Lactente , Recém-Nascido , Masculino , Polidioxanona/efeitos adversos , Traqueomalácia/terapia
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