RESUMO
Violence and drug abuse are highly destructive phenomena found world-wide, especially in Brazil. They seem to rise proportionally to one another and possibly related. Additionally, genetics may also play a role in drug abuse. This study has focused on identifying the use of cocaine within postmortem cases arriving at the Institute of Legal Medicine of Sao Paulo as well as the presence of certain single nucleotide polymorphisms (SNPs) to better understand one's susceptibility to abuse the drug. Both hair and blood samples have been extracted through a simple methanol overnight incubation or a rapid dilute-and-shoot method, respectively. The samples were then analyzed using an UPLC-ESI-MS/MS and genotyped through RT-PCR. Statistical analyses were performed via SPSS software. From 105 postmortem cases, 53% and 51% of the cases shown to be positive for cocaine in hair and blood, respectively. Genetic wise, a significant difference has been observed for SNP rs4263329 from the BCHE gene with higher frequencies of the genotypes A/G and G/G seen in cocaine users (OR=8.91; 95%CI=1.58-50.21; p=0.01). Likewise, also SNP rs6280 from the DRD3 gene presented a significant association, with both genotypes T/C and C/C being more frequent in users (OR=4.96; 95% CI=1.07-23.02; p=0.04). To conclude, a rather high proportion of cocaine has been found, which may suggest a connotation between the use of the drug and risky/violent behaviors. Additionally, significant associations were also found within two SNPs related to cocaine use, however, due to several inherent limitations, these must be confirmed.
Assuntos
Butirilcolinesterase/genética , Transtornos Relacionados ao Uso de Cocaína/genética , Predisposição Genética para Doença , Polimorfismo de Nucleotídeo Único , Receptores de Dopamina D3/genética , Violência , Adulto , Alelos , Brasil , Cocaína/análise , Feminino , Genética Forense , Genótipo , Cabelo/química , Humanos , Masculino , Grupos Raciais/genéticaRESUMO
OBJECTIVE: The main aim of the study was to evaluate the efficacy and safety profile of Nivolumab, an immune-checkpoint-inhibitor antibody, in advanced, previously treated, Non-Small Cell Lung Cancer (NSCLC) patients, in a real world setting. METHODS: We performed a retrospective, multicentre data analysis of patients who were included in the Portuguese Nivolumab Expanded Access Program (EAP). Eligibility criteria included histologically or citologically confirmed NSCLC, stage IIIB and IV, evaluable disease, sufficient organ function and at least one prior line of chemotherapy. The endpoints included Overall Response Rate (ORR), Disease Control Rate (DCR), Progression Free Survival (PFS) and Overall Survival (OS). Safety analysis was performed with the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 4.0, and immune-related Adverse Events (irAEs) were treated according to protocol treatment guidelines. Tumour response was assessed using the Response Evaluation Criteria in Solid Tumours (RECIST) version 1.1. Data was analysed using SPSS, version 21.0 (IBM Statistics). RESULTS: From June 2015 to December 2016, a total of 229 patients with advanced NSCLC were enrolled at 30 Portuguese centres. Clinical data were collected up to the end of July 2018. The baseline median age was 64 years (range 37-83) and the majority of patients were males (70.3%) and former/current smokers (69.4%). Patients with non-squamous histology predominated (88.1%), and 67.6% of the patients had received 2 or more prior lines of chemotherapy. Out of 229 patients, data was available for 219 patients (3 patients did not start treatment, while data was unavailable in 7 patients); of the 219 patients, 15.5% were not evaluated for radiological tumour assessment, 1.4% had complete response (CR), 21% partial response (PR), 31% stable disease (SD) and 31.1% progressive disease (PD). Thus, the ORR was 22.4% and DCR was 53.4% in this population. At the time of survival analysis the median PFS was 4.91 months (95% CI, 3.89-6.11) and median OS was 13.21 months (95% CI, 9.89-16.53). The safety profile was in line with clinical trial data. CONCLUSIONS: Efficacy and safety results observed in this retrospective analysis were consistent with observations reported in clinical trials and from other centres.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Nivolumabe/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos Imunológicos/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma Pulmonar de Células não Pequenas/epidemiologia , Feminino , Humanos , Incidência , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/epidemiologia , Masculino , Pessoa de Meia-Idade , Portugal/epidemiologia , Intervalo Livre de Progressão , Estudos Retrospectivos , Taxa de Sobrevida/tendências , Resultado do TratamentoRESUMO
Current opinion holds that pores in synthetic nerve guides facilitate nerve regeneration. Solid factual support for this opinion, however, is absent; most of the relevant studies assessed only morphological parameters and results have been contradictory. To evaluate the effect of pores, the rat sciatic nerve was either autografted or grafted with nonporous, macroporous (10-230 mum), and microporous (1-10 microm) biodegradable epsilon-caprolactone grafts. Twelve weeks later, the grafted nerves were resected, and the electrophysiological properties were determined in vitro. Subsequently midgraft-level sections were inspected, and peroneal nerve sections were evaluated morphometrically. Finally, the gastrocnemic and tibial muscle morphometrical properties were quantified. The microporous nerve graft performed much better than the nonporous and macroporous grafts with respect to most parameters: it was bridged by a free floating bundle that contained myelinated nerve fibers, there were more nerve fibers present distal to the graft, the electrophysiological response rate was higher, and the decrease in muscle cross-sectional area was markedly smaller. Hence, the present study demonstrates the beneficial effect of synthetic nerve guide pores on nerve regeneration, although with the caveat that not pores per se, but only small (1-10 microm) pores were effective.
Assuntos
Implantes Absorvíveis , Caproatos , Lactonas , Regeneração Nervosa , Nervo Isquiático/lesões , Animais , Feminino , Teste de Materiais , Porosidade , Ratos , Ratos Wistar , Nervo Isquiático/patologiaRESUMO
UNLABELLED: Primary chemotherapy is increasingly used in patients with large operable breast cancer. Docetaxel and epirubicin are the most active agents in breast cancer treatment. PURPOSE: To evaluate clinical response rate, breast conserving surgery and pathological response rate in patients with large operable breast cancer treated with docetaxel followed by docetaxel and epirubicin as primary chemotherapy. PATIENTS AND METHODS: Patients with operable breast cancer more than 3 cm in the longest diameter with T2N0, T2N1 and T3N0 disease were enrolled. Patients were treated with three cycles of docetaxel 100 mg/m2 followed by three cycles of docetaxel 75 mg/m2 and epirubicin 90 mg/m2 prior to surgery. RESULTS: Sixty-five patients were enrolled between 09/2002 and 12/2005. The median age was 48.9 years and 72.3% were premenopausal. Median tumour size was 4.26 cm, 10.8% were T3 tumours and 38.5% had clinical positive lymph nodes. Of the tumours 58.5% were grade 1/2, 33.9% ER positive and 21.5% c-erb negative. All six cycles were administered to 62 patients; six cycles were delayed and five had dose reductions. Complete clinical response occurred in 41.5% of patients and partial response in 49.2%. Breast conserving surgery was performed in 30% of patients however it was feasible in 57%. Complete pathological response occurred in both primary tumour and nodes in 28%, and in 34% just in the primary tumour. Nine percent of cases had neutropenia and 7.7% febrile neutropenia, and two cases had a hypersensitivity reaction to docetaxel. One associated treatment death occurred. CONCLUSION: Docetaxel followed by epirubicin and docetaxel as primary chemotherapy results in a high clinical and pathological response rate. The majority of adverse events were predictable and manageable.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Adulto , Neoplasias da Mama/cirurgia , Terapia Combinada , Docetaxel , Esquema de Medicação , Epirubicina/administração & dosagem , Feminino , Humanos , Pessoa de Meia-Idade , Taxoides/administração & dosagemRESUMO
TiO2 is able to scavenge reactive oxygen and nitrogen species (ROS and RNS) in the absence of light. The scavenging mechanism has been related to the chemistry of defects (oxygen vacancy reduced oxidation states of Ti) but it is still unknown. This study describes the ROS scavenging activity of different titanium oxide phases and relates their scavenging activities with the Ti4+/Ti3+ molar ratio as well as the band gap value. The Ti5O9 phase, with a mixture of both oxidation states, presented a substantially higher percentage of 2,2-diphenyl-1-picrylhydracyl radicals (DPPHË) eliminated per m2 of specific surface area in comparison to phases with predominant oxidation states Ti4+ or Ti3+ such as TiO2 and Ti2O3, respectively. The obtained results indicate that the DPPHË scavenging mechanism corresponds to a catalytic process on the Ti5O9 surface which is facilitated by the presence of charges that can easily move through the material. The mobility of charges and electrons in the semiconductor surface, related to the presence of oxidation states Ti4+ and Ti3+ and a small band gap, could create an attractive surface for radical species such as DPPHË. This puts forward Ti5O9 as a promising candidate coating for implantable biomedical devices, as an electrode, since it can cushion inflammatory processes which could lead to device encapsulation and, consequently, failure.
RESUMO
Hair testing is a recognized approach when it comes to accessing historical drug use. According to the World Drug Report of United Nations Office on Drugs and Crime (UNODC) 2015, Brazil is the largest cocaine (COC) market in South America. New analytical methodologies to detect crack/cocaine analytes in hair samples are highly desirable. Here, a method consisting of a liquid-phase microextraction (LPME) as a clean-up step, followed by gas chromatography-mass spectrometry (GC-MS) analysis has been proposed. The new validated method consisted of a washing step; an overnight incubation with methanol and a quick derivatization with butylchloroformate. Once derivatized, the samples were then submitted to the LPME procedure. Limits of detection (LoD) and quantitation (LoQ) obtained were of 0.1 and 0.5ng/mg for COC 0.4 and 0.5ng/mg for anhydroecgonine methyl ester (AEME); 0.03 and 0.05 for cocaethylene (CE), respectively and 0.05ng/mg for both LoD and LoQ for benzoylecgonine (BZE). All calibration curves were linear over the scope applied, from LoQ up to 20ng/mg, with a r2>0.99. Precision and accuracy assays showed acceptable %RSD values, according to international guidelines. Twelve postmortem head hair samples stemming from the Institute of Legal Medicine of Sao Paulo (IML-SP) have been analyzed, from which seven have shown to be positive for COC (0.75->20ng/mg) and BZE (0.1->20ng/mg). Apart from COC's main metabolite, four samples were also positive for CE (0.1-3.9ng/mg) and three samples for AEME (0.5-4.9ng/mg). To conclude, the LPME technique together with GC-MS analysis have shown promising results and were able to meet the demand of the laboratory of analyzing postmortem hair samples to look for all four analytes.
Assuntos
Cocaína/análise , Cabelo/química , Entorpecentes/análise , Transtornos Relacionados ao Uso de Cocaína/diagnóstico , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Limite de Detecção , Microextração em Fase Líquida , Detecção do Abuso de Substâncias/métodosRESUMO
OBJECTIVES: Tobacco exposure remains the main etiologic factor for lung cancer (LC). Interactions between environment and individual genetic profile are particularly important for this disease. The aim of this study was to evaluate the contribution of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 polymorphisms for the susceptibility to LC in a Portuguese population considering their demographic and clinical characteristics. MATERIALS AND METHODS: A total of 200 LC and 247 controls subjects from the Centre of Portugal were studied. Clinical and demographic characteristics were collected from clinical files and by individual questionnaires. Polymorphisms of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 were genotyped using PCR-RFLP, PCR multiplex, ARMS and real time. RESULTS: Gender, family history of cancer, smoke cessation and alcohol consumption were independent risk factors (p < 0.05). Associations found between phases I and II genes and LC population reveal a sex dependent distribution. Logistic regression analysis demonstrates that enhanced activation by CYPs, associated by reduced or loss of function of phase II enzymes, can lead to a greater risk. GSTP1 and NAT2 polymorphisms studied have a significant contribution for the histological tumour types and the presence of metastases, at time of diagnosis, respectively, when males with smoking habits were considered. CONCLUSION: Multiple interactions between environment and individual characteristics are clearly associated to this disease. Variants of the detoxification genes may act synergistically contributing to this disease and modifying the risk posed by smoking and sex. The GSTT1*0 and GSTP1 (Ile462Val) might contribute to the malignant phenotype through different mechanisms.
Assuntos
Arilamina N-Acetiltransferase/genética , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP2D6/genética , Interação Gene-Ambiente , Glutationa Transferase/genética , Neoplasias Pulmonares/genética , Polimorfismo Genético , Adulto , Idoso , Consumo de Bebidas Alcoólicas , Estudos de Casos e Controles , Feminino , Predisposição Genética para Doença , Genótipo , Glutationa S-Transferase pi/genética , Humanos , Modelos Logísticos , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/patologia , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Razão de Chances , Portugal , Fatores de Risco , Fatores Sexuais , Fumar/efeitos adversos , Inquéritos e Questionários , Análise de SobrevidaRESUMO
This study attempts to correlate levels of ADA in tuberculous and neoplastic pleural exudates with the different immunologic cellular expressions that follow these clinical situations. Seventy-three patients with pleural effusion were studied in order to assess ADA activity (pleural and serum); in 25 of them, a study of delayed cellular immunity (pleural and sanguineous) was performed through B, CD3, CD4, and CD8 lymphocytic populations. The activity of ADA was determined, and the study of lymphocytic populations was made through the use of monoclonal antibodies. The data obtained showed the following: levels of ADA were significantly (p less than 0.0005) higher in the pleural fluid and the serum of tuberculous effusions compared to neoplastic effusions; percentages of CD3 and CD4 T-cells were significantly (p less than 0.05 and p less than 0.0005, respectively) greater in tuberculous effusions. The statistical study of the levels of ADA activity and the percentage of CD4 T-cells in pleural exudates produced a significant regression curve (r = 0.612 and p less than 0.0001) which showed a positive correlation between these two parameters. The pathogenic implications of these results suggest the possibility that ADA could be a new marker of cell-mediated immune activity.
Assuntos
Adenosina Desaminase/sangue , Epitopos , Nucleosídeo Desaminases/sangue , Derrame Pleural/enzimologia , Neoplasias Pleurais/enzimologia , Linfócitos T/imunologia , Tuberculose Pleural/enzimologia , Adenosina Desaminase/análise , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Linfócitos B/patologia , Criança , Feminino , Humanos , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Derrame Pleural/patologia , Neoplasias Pleurais/patologia , Linfócitos T/patologia , Linfócitos T Auxiliares-Indutores/patologia , Linfócitos T Reguladores/patologia , Tuberculose Pleural/patologiaRESUMO
Attachment to and proliferation on the substrate are deemed important considerations when Schwann cells (SCs) are to be seeded in synthetic nerve grafts. Attachment is a prerequisite for the SCs to survive and fast proliferation will yield large numbers of SCs in a short time, which appears promising for stimulation of peripheral nerve regeneration. The aim of the present study was to compare the adhesion and proliferation of human Schwann cells (HSCs) on different substrates. The following were selected for their suitability as an internal coating of synthetic nerve grafts; the extracellular matrix proteins fibronectin, laminin and collagen type I and the poly-electrolytes poly(d-lysine) (PDL) and poly(ethylene-imine) (PEI). On all coatings, attachment of HSCs was satisfactory and comparable, indicating that this factor is not a major consideration in choosing a suitable coating. Proliferation was best on fibronectin, laminin and PDL, and worst on collagen type I and PEI. Since nerve regeneration is enhanced by laminin and/or fibronectin, these are preferred as coatings for synthetic nerve grafts seeded with SCs.
Assuntos
Materiais Revestidos Biocompatíveis/química , Teste de Materiais , Células de Schwann/citologia , Células de Schwann/fisiologia , Engenharia Tecidual/métodos , Adesão Celular , Divisão Celular , Células Cultivadas , Colágeno Tipo I/química , Proteínas da Matriz Extracelular/química , Humanos , Polietilenoimina/química , Polilisina/química , Adesivos Teciduais/químicaRESUMO
Biodegradable porous scaffolds for heart tissue engineering were prepared from amorphous elastomeric (co)polymers of 1,3-trimethylene carbonate (TMC) and D,L-lactide (DLLA). Leaching of salt from compression-molded polymer-salt composites allowed the preparation of highly porous structures in a reproducible fashion. By adjusting the salt particle size and the polymer-to-particle weight ratio in the polymer-salt composite preparation the pore size and porosity of the scaffolds could be precisely controlled. The thermal properties of the polymers used for scaffold preparation had a strong effect on the morphology, mechanical properties and dimensional stability of the scaffolds under physiological conditions. Interconnected highly porous structures (porosity, 94%; average pore size, 100 microm) based on a TMC-DLLA copolymer (19:81, mol%) had suitable mechanical properties and displayed adequate cell-material interactions to serve as scaffolds for cardiac cells. This copolymer is noncytotoxic and allows the adhesion and proliferation of cardiomyocytes. During incubation in phosphate-buffered saline at 37 degrees C, these scaffolds were dimensionally stable and the number average molecular weight (Mn) of the polymer decreased gradually from 2.0 x 10(5) to 0.3 x 10(5) in a period up to 4 months. The first signs of mass loss (5%) were detected after 4 months of incubation. The degradation behavior of the porous structures was similar to that of nonporous films with similar composition and can be described by autocatalyzed bulk hydrolysis.
Assuntos
Materiais Biocompatíveis , Miocárdio , Polímeros , Engenharia Tecidual , Materiais Biocompatíveis/síntese química , Células Endoteliais , Microscopia Eletrônica de Varredura , Polímeros/síntese químicaRESUMO
The degradation and the tissue response evoked by poly(1,3-trimethylene carbonate) [poly(TMC)] and copolymers of TMC with either 52 mol % D,L-lactide (DLLA) or 89 mol % epsilon-caprolactone (CL) were evaluated in vivo by subcutaneous implantation of polymer films in rats for periods up to one year. Poly(TMC) specimens were extensively degraded after 3 weeks and, as confirmed by histology, totally resorbed in less than a year. A fast linear decrease in thickness and mass without a change in molecular weight was observed. Initially an acute sterile inflammatory tissue reaction, caused by the implantation procedure, was observed, followed by a mild macrophage-mediated foreign body reaction that lasted during the resorption period of the polymer. It is concluded that in vivo, poly(TMC) is degraded via surface erosion involving cellular-mediated processes. The degradation of the copolymers was slower than that of poly(TMC), taking place via autocatalyzed bulk hydrolysis, preferentially of ester bonds. The TMC-DLLA copolymer degraded 20 times faster than the TMC-CL one. In both cases, the tissue reaction upon implantation resembled a sterile inflammatory reaction followed by a foreign body reaction that led to the polymer encapsulation. Significant mass loss was only observed for the TMC-DLLA copolymer, which underwent 96% mass loss in 1 year. When extensive mass loss started, a mild-to-moderate secondary foreign body reaction, related to clearance of the polymer fragments, was triggered. The results presented in this study demonstrate that poly(TMC) and both TMC copolymers are biodegradable and biocompatible materials, making these polymers attractive for the preparation of short- and long-term degradable devices for soft tissue engineering.
Assuntos
Materiais Biocompatíveis/química , Implantes Experimentais , Polímeros/farmacologia , Animais , Materiais Biocompatíveis/farmacologia , Biodegradação Ambiental , Dioxanos/farmacologia , Reação a Corpo Estranho , Inflamação , Masculino , Teste de Materiais , Poliésteres/farmacologia , Polímeros/química , Ratos , Ratos Wistar , Engenharia Tecidual/métodosRESUMO
The present study aimed to develop a pre-endothelialized chitosan (CH) porous hollowed scaffold for application in spinal cord regenerative therapies. CH conduits with different degrees of acetylation (DA; 4% and 15%) were prepared, characterized (microstructure, porosity and water uptake) and functionalized with a recombinant fragment of human fibronectin (rhFNIII(7-10)). Immobilized rhFNIII(7-10) was characterized in terms of amount ((125)I-radiolabelling), exposure of cell-binding domains (immunofluorescence) and ability to mediate endothelial cell (EC) adhesion and cytoskeletal rearrangement. Functionalized conduits revealed a linear increase in immobilized rhFNIII(7-10) with rhFNIII(7-10) concentration, and, for the same concentration, higher amounts of rhFNIII(7-10) on DA 4% compared with DA 15%. Moreover, rhFNIII(7-10) concentrations as low as 5 and 20µg ml(-1) in the coupling reaction were shown to provide DA 4% and 15% scaffolds, respectively, with levels of exposed cell-binding domains exceeding those observed on the control (DA 4% scaffolds incubated in a 20µg ml(-1) human fibronectin solution). These grafting conditions proved to be effective in mediating EC adhesion/cytoskeletal organization on CH with DA 4% and 15%, without affecting the endothelial angiogenic potential. rhFNIII(7-10) grafting to CH could be a strategy of particular interest in tissue engineering applications requiring the use of endothelialized porous matrices with tunable degradation rates.
Assuntos
Quitosana/farmacologia , Células Endoteliais/fisiologia , Fibronectinas/farmacologia , Proteínas Imobilizadas/farmacologia , Proteínas Recombinantes/farmacologia , Alicerces Teciduais/química , Adsorção , DNA/metabolismo , Células Endoteliais/efeitos dos fármacos , Fibronectinas/química , Fibronectinas/isolamento & purificação , Corantes Fluorescentes/metabolismo , Humanos , Proteínas Imobilizadas/química , Proteínas Imobilizadas/isolamento & purificação , Microscopia Eletrônica de Varredura , Neovascularização Fisiológica/efeitos dos fármacos , Porosidade , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Deciduoid Mesothelioma is a rare variant of epithelioid mesothelioma; it was initially thought that it only occurred in the peritoneum of young women and had nothing to do with asbestos exposure. However, since these early findings it has also been observed in the pleura and the pericardium, with possible association to asbestos. In general the prognosis is poor compared to epithelioid mesothelioma. 45 cases have been reported in the literature up to now, 22 of these were located in the pleural cavity. The authors describe a case of deciduoid pleural mesothelioma in a 40-year-old-woman who presented with right pleuritic chest pain, with no history of asbestos exposure, treated with chemotherapy followed by surgery and who died postoperatively.
Assuntos
Mesotelioma , Neoplasias Pleurais , Adulto , Feminino , Humanos , Mesotelioma/diagnóstico , Mesotelioma/terapia , Neoplasias Pleurais/diagnóstico , Neoplasias Pleurais/terapiaRESUMO
Chitosan was functionalized with imidazole moieties (CHimi) with the aim of improving its buffering capacity and promoting the endosomal escape ability of chitosan-DNA complexes, ultimately increasing their transfection efficiency. 5.6%, 12.9% and 22.1% of the glucosamine residues of chitosan were substituted. Complexes with different molar ratios of primary amines to DNA phosphate anion (N/P) were prepared by a coacervation method. For an N/P>3, CHimi polymers are able to complex electrostatically with DNA and condense it into positively charged nanostructures (average size 260 nm and zeta potential +16 mV at pH 5.5). In the concentration range 2.5-100 microg ml(-1), the modified polymers had no cytotoxic effect on 293T cells. CHimi polymers with the highest degree of substitution were found to enhance beta-gal expression in 293T and HepG2 cells. Bafilomycin A1 inhibited transfection, indicating that the protonation of the imidazole groups in the endolysosome pathway favors the escape of the complexes from the endosomes, increasing the amount of transgene that can reach the cell nucleus.
Assuntos
Materiais Biocompatíveis/química , Quitosana/química , DNA/química , DNA/farmacocinética , Portadores de Fármacos/química , Composição de Medicamentos/métodos , Rim/metabolismo , Transfecção/métodos , Soluções Tampão , Linhagem Celular , DNA/administração & dosagem , Difusão , Humanos , Teste de MateriaisRESUMO
Type grouping signifies clustering of muscle fibres of the same metabolic type, and is a frequent finding in reinnervated muscles. To elucidate the mechanism behind it, the rat sciatic nerve was either autografted or grafted with hollow synthetic nerve grafts. Twelve weeks later the number and fibre area of the type I and type II muscle fibres in the gastrocnemic and anterior tibial muscles were determined after ATP-ase staining. The number and diameter of peroneal nerve fibres distal to the grafts were measured, and the number of Aalpha-nerve fibres was derived. Nearly all nerve and muscle morphometrical parameters changed equally in both experimental groups. However, type grouping occurred frequently only after autografting, whereas the number of nerve fibres and the number of Aalpha-nerve fibres increased in this group. Hence type grouping cannot be explained by increased intramuscular sprouting subsequent to a decrease in the number of innervating nerve fibres, as previously presumed. Regenerating axons branch along their course through the peripheral nerve. We propose that the probability of the occurrence of type grouping is related to the dispersion of sibling branches in the nerve. In the autograft, emerging branches are kept together by Schwann cell basal lamina scaffolds, in contrast to the hollow synthetic nerve grafts where the emerging branches become dispersed. Thus, in muscles reinnervated after autografting, the probability that nerve branches that arrive at a specific muscle territory are sibling branches is greater than after hollow tube grafting. Consequently, the probability that type grouping will occur is greater.
Assuntos
Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/inervação , Regeneração Nervosa/fisiologia , Nervo Fibular/lesões , Adenosina Trifosfatases/metabolismo , Animais , Dioxanos/provisão & distribuição , Feminino , Modelos Animais , Denervação Muscular/métodos , Fibras Musculares Esqueléticas/classificação , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/patologia , Músculo Esquelético/fisiopatologia , Fibras Nervosas Mielinizadas/fisiologia , Fibras Nervosas Mielinizadas/transplante , Nervo Fibular/patologia , Nervo Fibular/cirurgia , Nervo Fibular/ultraestrutura , Próteses e Implantes , Distribuição Aleatória , Ratos , Ratos Wistar , Nervo Isquiático/transplante , Coloração e Rotulagem/métodos , Transplante Autólogo/métodosRESUMO
Copolymers of trimethylene carbonate and epsilon-caprolactone were synthesized and characterized with the aim of assessing their potential in the development of a flexible and slowly degrading artificial nerve guide for the bridging of large nerve defects. The effect of the monomer ratio on the physical properties of the polymers and its influence on the processability of the materials was investigated. Under the applied polymerization conditions (130 degrees C, 3 days using stannous octoate as a catalyst) high molecular weight polymers (Mn above 93 000) were obtained. All copolymers had glass transition temperatures below room temperature. At trimethylene carbonate contents higher than 25 mol% no crystallinity was detected. A decrease in crystallinity resulted in the loss of strength and decrease in toughness, as well as in an increased polymer wettability. Amorphous poly(trimethylene carbonate), however, showed excellent ultimate mechanical properties due to strain-induced crystallization (Tm = 36 degrees C). Low crystallinity copolymers could be processed into dimensionally stable porous structures by means of immersion precipitation and by combination of this technique with the use of porosifying agents. Porous membranes of poly(trimethylene carbonate) could be prepared when blended with small amounts of high molecular weight poly(ethylene oxide). Poly(trimethylene carbonate) and poly(trimethylene carbonate-co-epsilon-caprolactone) copolymers with high epsilon-caprolactone content possess good physical properties and are processable into porous structures. These materials are most suitable for the preparation of porous artificial nerve guides.