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1.
Cell ; 172(5): 897-909.e21, 2018 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-29474918

RESUMO

X-linked Dystonia-Parkinsonism (XDP) is a Mendelian neurodegenerative disease that is endemic to the Philippines and is associated with a founder haplotype. We integrated multiple genome and transcriptome assembly technologies to narrow the causal mutation to the TAF1 locus, which included a SINE-VNTR-Alu (SVA) retrotransposition into intron 32 of the gene. Transcriptome analyses identified decreased expression of the canonical cTAF1 transcript among XDP probands, and de novo assembly across multiple pluripotent stem-cell-derived neuronal lineages discovered aberrant TAF1 transcription that involved alternative splicing and intron retention (IR) in proximity to the SVA that was anti-correlated with overall TAF1 expression. CRISPR/Cas9 excision of the SVA rescued this XDP-specific transcriptional signature and normalized TAF1 expression in probands. These data suggest an SVA-mediated aberrant transcriptional mechanism associated with XDP and may provide a roadmap for layered technologies and integrated assembly-based analyses for other unsolved Mendelian disorders.


Assuntos
Distúrbios Distônicos/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Genoma Humano , Transcriptoma/genética , Processamento Alternativo/genética , Elementos Alu/genética , Sequência de Bases , Sistemas CRISPR-Cas/genética , Estudos de Coortes , Família , Feminino , Loci Gênicos , Haplótipos/genética , Sequenciamento de Nucleotídeos em Larga Escala , Histona Acetiltransferases/genética , Histona Acetiltransferases/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Íntrons/genética , Masculino , Repetições Minissatélites/genética , Modelos Genéticos , Degeneração Neural/genética , Degeneração Neural/patologia , Células-Tronco Neurais/metabolismo , Neurônios/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Elementos Nucleotídeos Curtos e Dispersos , Fatores Associados à Proteína de Ligação a TATA/genética , Fatores Associados à Proteína de Ligação a TATA/metabolismo , Fator de Transcrição TFIID/genética , Fator de Transcrição TFIID/metabolismo
2.
Pediatr Nephrol ; 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38526761

RESUMO

Paediatric acute liver failure (PALF) is often characterised by its rapidity of onset and potential for significant morbidity and even mortality. Patients often develop multiorgan dysfunction/failure, including severe acute kidney injury (AKI). Whilst the management of PALF focuses on complications of hepatic dysfunction, the associated kidney impairment can significantly affect patient outcomes. Severe AKI requiring continuous kidney replacement therapy (CKRT) is a common complication of both PALF and liver transplantation. In both scenarios, the need for CKRT is a poor prognostic indicator. In adults, AKI has been shown to complicate ALF in 25-50% of cases. In PALF, the incidence of AKI is often higher compared to other critically ill paediatric ICU populations, with reports of up to 40% in some observational studies. Furthermore, those presenting with AKI regularly have a more severe grade of PALF at presentation. Observational studies in the paediatric population corroborate this, though data are not as robust-mainly reflecting single-centre cohorts. Perioperative benefits of CKRT include helping to clear water-soluble toxins such as ammonia, balancing electrolytes, preventing fluid overload, and managing raised intracranial pressure. As liver transplantation often takes 6-10 h, it is proposed that these benefits could be extended to the intraoperative period, avoiding any hiatus. Intraoperative CKRT (IoCKRT) has been shown to be practicable, safe and may help sicker recipients tolerate the operation with outcomes analogous with less ill patients not requiring IoCKRT. Here, we provide a comprehensive guide describing the rationale, practicalities, and current evidence base surrounding IoCKRT during transplantation in the paediatric population.

3.
Lancet Oncol ; 23(10): 1308-1320, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36113498

RESUMO

BACKGROUND: Localised prostate cancer is commonly treated with external beam radiotherapy and moderate hypofractionation is non-inferior to longer schedules. Stereotactic body radiotherapy (SBRT) allows shorter treatment courses without impacting acute toxicity. We report 2-year toxicity findings from PACE-B, a randomised trial of conventionally fractionated or moderately hypofractionated radiotherapy versus SBRT. METHODS: PACE is an open-label, multicohort, randomised, controlled, phase 3 trial conducted at 35 hospitals in the UK, Ireland, and Canada. In PACE-B, men aged 18 years and older with a WHO performance status 0-2 and low-risk or intermediate-risk histologically-confirmed prostate adenocarcinoma (Gleason 4 + 3 excluded) were randomly allocated (1:1) by computerised central randomisation with permuted blocks (size four and six), stratified by centre and risk group to control radiotherapy (CRT; 78 Gy in 39 fractions over 7·8 weeks or, following protocol amendment on March 24, 2016, 62 Gy in 20 fractions over 4 weeks) or SBRT (36·25 Gy in five fractions over 1-2 weeks). Androgen deprivation was not permitted. Co-primary outcomes for this toxicity analysis were Radiation Therapy Oncology Group (RTOG) grade 2 or worse gastrointestinal and genitourinary toxicity at 24 months after radiotherapy. Analysis was by treatment received and included all patients with at least one fraction of study treatment assessed for late toxicity. Recruitment is complete. Follow-up for oncological outcomes continues. The trial is registered with ClinicalTrials.gov, NCT01584258. FINDINGS: We enrolled and randomly assigned 874 men between Aug 7, 2012, and Jan 4, 2018 (441 to CRT and 433 to SBRT). In this analysis, 430 patients were analysed in the CRT group and 414 in the SBRT group; a total of 844 (97%) of 874 randomly assigned patients. At 24 months, RTOG grade 2 or worse genitourinary toxicity was seen in eight (2%) of 381 participants assigned to CRT and 13 (3%) of 384 participants assigned to SBRT (absolute difference 1·3% [95% CI -1·3 to 4·0]; p=0·39); RTOG grade 2 or worse gastrointestinal toxicity was seen in 11 (3%) of 382 participants in the CRT group versus six (2%) of 384 participants in the SBRT group (absolute difference -1·3% [95% CI -3·9 to 1·1]; p=0·32). No serious adverse events (defined as RTOG grade 4 or worse) or treatment-related deaths were reported within the analysis timeframe. INTERPRETATION: In the PACE-B trial, 2-year RTOG toxicity rates were similar for five fraction SBRT and conventional schedules of radiotherapy. Prostate SBRT was found to be safe and associated with low rates of side-effects. Biochemical outcomes are awaited. FUNDING: Accuray.


Assuntos
Neoplasias da Próstata , Radiocirurgia , Radioterapia de Intensidade Modulada , Androgênios , Humanos , Masculino , Neoplasias da Próstata/patologia , Radiocirurgia/efeitos adversos , Radioterapia de Intensidade Modulada/efeitos adversos , Radioterapia de Intensidade Modulada/métodos , Resultado do Tratamento
4.
Intern Med J ; 52(1): 63-68, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33025684

RESUMO

BACKGROUND: The impact of an acute pulmonary exacerbation of cystic fibrosis (CF) on sleep quality has not been established. Patients have greater burden of symptoms, higher intensity of therapy and are often admitted to hospital outside of their usual sleeping environment. AIMS: To evaluate the prevalence of, and factors associated with, poor sleep quality in adult patients admitted to hospital with an acute exacerbation of CF lung disease. METHODS: This prospective, observational study determined the prevalence of impaired sleep quality and associated factors in adult patients admitted to a single CF unit with an acute pulmonary exacerbation of CF. Sleep quality was defined by the Pittsburgh Sleep Quality Index (PSQI), with >5 indicating poor sleep quality. Data were obtained through patient questionnaires, chart review and examination. RESULTS: Sixty-six percent of patients had impaired sleep quality. Patients with poor sleep had more sleep disruption due to pain (median response 'mild sleep disruption' vs 'no sleep disruption'; P = 0.003) and insomnia (mean Insomnia Severity Index (ISI) 13 vs 5; P < 0.001). In patients with symptoms of restless legs, poor sleepers had worse symptoms (mean International Restless Legs Severity Score (IRLSS) 15 vs 5; P = 0.029). Univariate modelling showed relationships between PSQI and symptoms of depression and anxiety as well as with sleep disruption due to pain, general noise and nursing observations. In a multivariable model, ISI was the only variable that remained significantly associated with PSQI. Mean PSQI score increased 0.58 units for each 1 unit increase in ISI (95% CI 0.42-0.73; P < 0.001). CONCLUSIONS: Poor sleep quality is common among patients admitted with an acute exacerbation of CF and is strongly associated with insomnia symptoms in this cohort.


Assuntos
Fibrose Cística , Adulto , Estudos de Coortes , Fibrose Cística/complicações , Fibrose Cística/epidemiologia , Humanos , Estudos Prospectivos , Sono/fisiologia , Qualidade do Sono
5.
BMC Musculoskelet Disord ; 22(1): 378, 2021 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-33888115

RESUMO

BACKGROUND: While supraspinatus atrophy can be described according to the system of Zanetti or Thomazeau there is still a lack of characterization of isolated subscapularis muscle atrophy. The aim of this study was to describe patterns of muscle atrophy following repair of isolated subscapularis (SSC) tendon. METHODS: Forty-nine control shoulder MRI scans, without rotator cuff pathology, atrophy or fatty infiltration, were prospectively evaluated and subscapularis diameters as well as cross sectional areas (complete and upper half) were assessed in a standardized oblique sagittal plane. Calculation of the ratio between the upper half of the cross sectional area (CSA) and the total CSA was performed. Eleven MRI scans of patients with subscapularis atrophy following isolated subscapularis tendon tears were analysed and cross sectional area ratio (upper half /total) determined. To guarantee reliable measurement of the CSA and its ratio, bony landmarks were also defined. All parameters were statistically compared for inter-rater reliability, reproducibility and capacity to quantify subscapularis atrophy. RESULTS: The mean age in the control group was 49.7 years (± 15.0). The mean cross sectional area (CSA) was 2367.0 mm2 (± 741.4) for the complete subscapularis muscle and 1048.2 mm2 (± 313.3) for the upper half, giving a mean ratio of 0.446 (± 0.046). In the subscapularis repair group the mean age was 56.7 years (± 9.3). With a mean cross sectional area of 1554.7 mm2 (± 419.9) for the complete and of 422.9 mm2 (± 173.6) for the upper half of the subscapularis muscle, giving a mean CSA ratio of 0.269 (± 0.065) which was seen to be significantly lower than that of the control group (p < 0.05). CONCLUSION: Analysis of typical atrophy patterns of the subscapularis muscle demonstrates that the CSA ratio represents a reliable and reproducible assessment tool in quantifying subscapularis atrophy. We propose the classification of subscapularis atrophy as Stage I (mild atrophy) in case of reduction of the cross sectional area ratio < 0.4, Stage II (moderate atrophy) in case of < 0.35 and Stage III (severe atrophy) if < 0.3.


Assuntos
Lesões do Manguito Rotador , Manguito Rotador , Artroscopia , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Atrofia Muscular/diagnóstico por imagem , Atrofia Muscular/patologia , Reprodutibilidade dos Testes , Manguito Rotador/diagnóstico por imagem , Manguito Rotador/patologia , Lesões do Manguito Rotador/diagnóstico por imagem , Lesões do Manguito Rotador/patologia
6.
Int Orthop ; 45(1): 199-208, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33210169

RESUMO

PURPOSE: Management of the subscapularis tendon during anatomic total shoulder arthroplasty (TSA) remains controversial. In our unit, subscapularis tenotomy is the preferred technique; however, the potential for tendon gapping and failure is recognised. The purpose of this study is to describe and provide early clinical results of a novel, laterally based V-shaped tenotomy (VT) technique hypothesised to provide greater initial repair strength and resistance to gapping than a transverse tenotomy (TT), with both clinically and radiologically satisfactory post-operative tendon healing and function. METHODS: A retrospective study of patients who underwent primary TSA with VT over a three year period was performed using shoulder and subscapularis-specific outcome scores, radiographs, and ultrasound. A separate cohort of patients who underwent TSA using a subscapularis sparing approach was also reviewed to provide comparative clinical outcomes of a group with TSA and an un-violated subscapularis. RESULTS: Eighteen patients were reviewed at mean 30.4 months (± 11.7). Constant (78.2 ± 12.3), UCLA (8.4 ± 1.5), pain VAS (2.3 ± 2.8), and strength in internal rotation were no different from the comparison group. Likewise, neither were the clinical outcomes of range-of-motion, belly-press, lift-off, and shirt-tuck tests. One patient (5.5%) was found to have a failed subscapularis repair on ultrasound. CONCLUSION: VT during TSA appears to provide healing rates at least equal to those reported for TT, and not dissimilar from those of lesser tuberosity osteotomy. Clinical outcomes are comparable to reported results in the literature for alternative techniques, and not different from those observed here in a comparison cohort with TSA performed without violating the subscapularis tendon. VT therefore potentially offers a more effective and secure tendon repair than a traditional TT, with at least comparable clinical outcomes.


Assuntos
Artroplastia do Ombro , Articulação do Ombro , Humanos , Estudos Retrospectivos , Manguito Rotador/cirurgia , Articulação do Ombro/diagnóstico por imagem , Articulação do Ombro/cirurgia , Tenotomia
7.
Lancet Oncol ; 20(11): 1531-1543, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31540791

RESUMO

BACKGROUND: Localised prostate cancer is commonly treated with external-beam radiotherapy. Moderate hypofractionation has been shown to be non-inferior to conventional fractionation. Ultra-hypofractionated stereotactic body radiotherapy would allow shorter treatment courses but could increase acute toxicity compared with conventionally fractionated or moderately hypofractionated radiotherapy. We report the acute toxicity findings from a randomised trial of standard-of-care conventionally fractionated or moderately hypofractionated radiotherapy versus five-fraction stereotactic body radiotherapy for low-risk to intermediate-risk localised prostate cancer. METHODS: PACE is an international, phase 3, open-label, randomised, non-inferiority trial. In PACE-B, eligible men aged 18 years and older, with WHO performance status 0-2, low-risk or intermediate-risk prostate adenocarcinoma (Gleason 4 + 3 excluded), and scheduled to receive radiotherapy were recruited from 37 centres in three countries (UK, Ireland, and Canada). Participants were randomly allocated (1:1) by computerised central randomisation with permuted blocks (size four and six), stratified by centre and risk group, to conventionally fractionated or moderately hypofractionated radiotherapy (78 Gy in 39 fractions over 7·8 weeks or 62 Gy in 20 fractions over 4 weeks, respectively) or stereotactic body radiotherapy (36·25 Gy in five fractions over 1-2 weeks). Neither participants nor investigators were masked to allocation. Androgen deprivation was not permitted. The primary endpoint of PACE-B is freedom from biochemical or clinical failure. The coprimary outcomes for this acute toxicity substudy were worst grade 2 or more severe Radiation Therapy Oncology Group (RTOG) gastrointestinal or genitourinary toxic effects score up to 12 weeks after radiotherapy. Analysis was per protocol. This study is registered with ClinicalTrials.gov, NCT01584258. PACE-B recruitment is complete and follow-up is ongoing. FINDINGS: Between Aug 7, 2012, and Jan 4, 2018, we randomly assigned 874 men to conventionally fractionated or moderately hypofractionated radiotherapy (n=441) or stereotactic body radiotherapy (n=433). 432 (98%) of 441 patients allocated to conventionally fractionated or moderately hypofractionated radiotherapy and 415 (96%) of 433 patients allocated to stereotactic body radiotherapy received at least one fraction of allocated treatment. Worst acute RTOG gastrointestinal toxic effect proportions were as follows: grade 2 or more severe toxic events in 53 (12%) of 432 patients in the conventionally fractionated or moderately hypofractionated radiotherapy group versus 43 (10%) of 415 patients in the stereotactic body radiotherapy group (difference -1·9 percentage points, 95% CI -6·2 to 2·4; p=0·38). Worst acute RTOG genitourinary toxicity proportions were as follows: grade 2 or worse toxicity in 118 (27%) of 432 patients in the conventionally fractionated or moderately hypofractionated radiotherapy group versus 96 (23%) of 415 patients in the stereotactic body radiotherapy group (difference -4·2 percentage points, 95% CI -10·0 to 1·7; p=0·16). No treatment-related deaths occurred. INTERPRETATION: Previous evidence (from the HYPO-RT-PC trial) suggested higher patient-reported toxicity with ultrahypofractionation. By contrast, our results suggest that substantially shortening treatment courses with stereotactic body radiotherapy does not increase either gastrointestinal or genitourinary acute toxicity. FUNDING: Accuray and National Institute of Health Research.


Assuntos
Adenocarcinoma/radioterapia , Neoplasias da Próstata/radioterapia , Hipofracionamento da Dose de Radiação , Radiocirurgia/efeitos adversos , Radioterapia de Intensidade Modulada/efeitos adversos , Adenocarcinoma/patologia , Idoso , Canadá , Humanos , Irlanda , Masculino , Gradação de Tumores , Neoplasias da Próstata/patologia , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Reino Unido
8.
BMC Musculoskelet Disord ; 20(1): 20, 2019 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-30630465

RESUMO

BACKGROUND: Proximal humeral fractures (PHFs) are the third most common fracture in older patients. The purpose of the study was to prospectively evaluate the outcomes of PHF fixation with a locking blade nail (LBN) or locking plate (PHILOS) osteosynthesis in a homogeneous elderly patient population. METHODS: Inclusion criteria were an age > 60 years and the capacity to give informed consent. Patients with isolated tuberosity fractures, previous trauma or surgery, advanced osteoarthritis, fracture dislocation, pathological fractures, open fractures, neurological disorders, full-thickness rotator cuff tears, fracture line at the nail entry point or severely reduced bone quality intra-operatively were excluded. Eighty one patients with PHFs were randomised to treatment using LBN or PHILOS. Outcome measures comprised Constant score, age and gender adjusted Constant score, DASH score, VAS for pain, subjective overall condition of the shoulder (1-6) and active shoulder range-of-motion in flexion and abduction. Plain radiographs were obtained in two planes. All data were collected by an independent observer at 3, 6 and 12 months postoperatively. RESULTS: Thirteen patients were excluded intra-operatively due to rotator cuff tears, fracture morphology or poor bone-quality. Of the remaining 68 patients, 27 in the LBN and 28 in the PHILOS group completed the full follow-up. Mean age at surgery was 75.6 years and the majority of PHFs were three-part fractures (49 patients). Baseline demographics between groups were comparable. All outcome measures improved between assessments (p < 0.001). The LBN group showed improved DASH scores as compared to PHILOS at 12 months (p = 0.042) with fewer incidences of secondary loss of reduction and screw cut-out (p = 0.039). A total of 29 complications (in 23 patients) were recorded, 13 complications (in 12 patients) in the LBN group and 16 complications (in 11 patients) in the PHILOS group (p = 0.941). No significant inter-group difference was observed for any other outcome measures, nor was fracture morphology seen to be associated with clinical outcome or complication rate. CONCLUSIONS: At short-term follow-up, LBN osteosynthesis yielded similar outcomes and complication rates to PHILOS plate fracture fixation in an elderly patient population, though with a significantly lower rate of secondary loss of reduction and screw cut-out. REGISTRATION TRIAL: No. DRKS00015245 at Deutsches Register Klinischer Studien, registered: 22.08.2018, retrospectively registered.


Assuntos
Pinos Ortopédicos/efeitos adversos , Placas Ósseas/efeitos adversos , Fixação Interna de Fraturas/instrumentação , Complicações Pós-Operatórias/epidemiologia , Fraturas do Ombro/cirurgia , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Fixação Interna de Fraturas/efeitos adversos , Fixação Interna de Fraturas/métodos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/etiologia , Estudos Prospectivos , Amplitude de Movimento Articular , Fraturas do Ombro/diagnóstico por imagem , Articulação do Ombro/diagnóstico por imagem , Articulação do Ombro/fisiologia , Resultado do Tratamento , Suporte de Carga
9.
J Shoulder Elbow Surg ; 28(12): 2356-2363, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31300368

RESUMO

HYPOTHESIS: This study investigated the hypothesis that reverse total shoulder arthroplasty (RSA) in combination with an isolated latissimus dorsi tendon (LDT) transfer in patients with pseudoparalysis of abduction and external rotation (combined loss of active elevation and external rotation [CLEER] syndrome) would demonstrate improved postoperative functional results. METHODS: This study was a retrospective single-surgeon case series of 13 consecutive patients with CLEER who underwent RSA without subscapularis repair and combined with an isolated LDT transfer. We reviewed 10 patients (77%), at a minimum of 2 years, with 3 cases lost to follow-up. Shoulder function was assessed preoperatively and postoperatively using the Constant score and postoperatively using the Oxford Shoulder Score, University of California-Los Angeles score, American Shoulder and Elbow Surgeons score, ADLEIR (activities of daily living [ADLs] requiring active external and internal rotation) score, and ADLIR (ADLs requiring active internal rotation) score. Force in internal rotation (IR) at 0° of abduction, external rotation (ER) at 0° of abduction, and ER at 90° of abduction, as well as IR in the belly-press position, was measured. RESULTS: The mean postoperative follow-up period was 57 months (range, 31-85 months). We observed improvement in the Constant score (from 29.8 ± 6.64 preoperatively to 71.9 ± 10.45 postoperatively, P < .05), as well as abduction force, ER, and forward elevation (P < .05). Postoperatively, the mean American Shoulder and Elbow Surgeons score was 95.1 ± 3.38 and the mean Oxford Shoulder Score was 46.6 ± 1.57. Mean force in IR at 0° of abduction was 5.45 ± 2.42 kg, and mean force in ER at 90° of abduction was 4 ± 1.20 kg. Mean force in ER at 0° of abduction (3.65 ± 1.24 kg) and IR in the belly-press position (4.5 ± 2.84 kg) demonstrated a positive correlation with ADLs. CONCLUSIONS: The results of this study demonstrate that RSA without subscapularis repair, combined with an isolated LDT transfer, provides improved postoperative functional outcomes for patients with CLEER while maintaining sufficiently balanced force in IR and ER to effectively perform ADLs.


Assuntos
Artroplastia do Ombro/métodos , Amplitude de Movimento Articular , Articulação do Ombro/fisiopatologia , Articulação do Ombro/cirurgia , Transferência Tendinosa , Atividades Cotidianas , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Rotação , Manguito Rotador/cirurgia , Músculos Superficiais do Dorso , Síndrome
10.
Clin Orthop Relat Res ; 475(5): 1472-1482, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27896679

RESUMO

BACKGROUND: The Taylor Spatial Frame™ (TSF) is a versatile variant of the traditional Ilizarov circular fixator. Although in widespread use, little comparative data exist to quantify the biomechanical effect of substituting the tried-and-tested Ilizarov construct for the TSF hexapod system. QUESTIONS/PURPOSES: This study was designed to investigate the mechanical properties of the TSF system under physiologic loads, with and without the addition of a simulated bone model, with comparison to the standard Ilizarov frame. METHODS: The mechanical behaviors of three identical four-ring TSF and Ilizarov constructs were tested under levels of axial compression, bending, and rotational torque to simulate loading during normal gait. An acrylic-pipe fracture model subsequently was mounted, using fine wires and 5 mm half pins, and the testing was repeated. Load-deformation curves, and so rigidity, for each construct were calculated, with statistical comparisons performed using paired t-tests. RESULTS: Under axial loading, the TSF was found to be less rigid than the Ilizarov frame (645 ± 57 N/mm versus 1269 ± 256 N/mm; mean difference, 623 N/mm; 95% CI, 438.3-808.5 N/mm; p < 0.001), but more rigid under bending and torsional loads (bending: 42 ± 9 Nm/degree versus 78 ± 13 Nm/degree; mean difference, 37 Nm/degree; 95% CI, 25.0-47.9 Nm/degree; p < 0.001; torsion: 16 ± 2 Nm/degree versus 5 ± 0.35 Nm/degree; mean difference, 11 Nm/degree; 95% CI, 9.5-12.2 Nm/degree; p < 0.001). On mounting the bone models, these relationships broadly remained in the half-pin and fine-wire groups, however the half-pin constructs were universally more rigid than those using fine wires. This effect resulted in the TSF, using half pins, showing no difference in axial rigidity to the fine-wire Ilizarov (107 ± 3 N/mm versus 107 ± 4 N/mm; mean difference, 0.05 N/mm; 95% CI, -6.99 to 7.1 N/mm; p > 0.999), while retaining greater bending and torsional rigidity. Throughout testing, a small amount of laxity was observed in the TSF construct on either side of neutral loading, amounting to 0.72 mm (±0.37 mm) for a change in loading between -10 N and 10 N axial load, and which persisted with the addition of the synthetic fracture model. CONCLUSIONS: This study broadly shows the TSF construct to generate lower axial rigidity, but greater bending and torsional rigidity, when compared with the Ilizarov frame, under physiologic loads. The anecdotally described laxity in the TSF hexapod strut system was shown in vitro, but only at low levels of loading around neutral. It also was shown that the increased stiffness generated by use of half pins produced a TSF construct replicating the axial rigidity of a fine-wire Ilizarov frame, for which much evidence of good clinical and radiologic outcomes exist, while providing greater rigidity and so improved resistance to potentially detrimental bending and rotational shear loads. CLINICAL RELEVANCE: If replicated in the clinical setting, these findings suggest that when using the TSF, care should be taken to minimize the observed laxity around neutral with appropriate preloading of the construct, but that its use may produce constructs better able to resist bending and torsional loading, although with lower axial rigidity. Use of half pins in a TSF construct however may replicate the axial mechanical behavior of an Ilizarov construct, which is thought to be conducive to bone healing.


Assuntos
Pinos Ortopédicos , Fixadores Externos , Técnica de Ilizarov/instrumentação , Fenômenos Biomecânicos , Força Compressiva , Desenho de Equipamento , Falha de Equipamento , Teste de Materiais , Rotação , Estresse Mecânico , Torque
11.
Clin Orthop Relat Res ; 474(4): 1041-9, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26642789

RESUMO

BACKGROUND: Fine-wire circular frame (Ilizarov) fixators are hypothesized to generate favorable biomechanical conditions for fracture healing, allowing axial micromotion while limiting interfragmentary shear. Use of half-pins increases fixation options and may improve patient comfort by reducing muscle irritation, but they are thought to induce interfragmentary shear, converting beam-to-cantilever loading. Little evidence exists regarding the magnitude and type of strain in such constructs during weightbearing. QUESTIONS/PURPOSES: This biomechanical study was designed to investigate the levels of interfragmentary strain occurring during physiologic loading of an Ilizarov frame and the effect on this of substituting half-pins for fine-wires. METHODS: The "control" construct was comprised of a four-ring all fine-wire construct with plain wires at 90°-crossing angles in an entirely unstable acrylic pipe synthetic fracture model. Various configurations, substituting half-pins for wires, were tested under levels of axial compression, cantilever bending, and rotational torque simulating loading during gait. In total three frames were tested for each of five constructs, from all fine-wire to all half-pin. RESULTS: Substitution of half-pins for wires was associated with increased overall construct rigidity and reduced planar interfragmentary motion, most markedly between all-wire and all-pin frames (axial: 5.9 mm ± 0.7 vs 4.2 mm ± 0.1, mean difference, 1.7 mm, 95% CI, 0.8-2.6 mm, p < 0.001; torsional: 1.4% ± 0.1 vs 1.1% ± 0.0 rotational shear, mean difference, 0.3%, 95% CI, 0.1%-0.5%, p = 0.011; bending: 7.5° ± 0.1 vs 3.4° ± 0.1, mean difference, -4.1°, 95% CI, -4.4° to -3.8°, p < 0.001). Although greater transverse shear strain was observed during axial loading (0.4% ± 0.2 vs 1.9% ± 0.1, mean difference, 1.4%, 95% CI, 1.0%-1.9%, p < 0.001), this increase is unlikely to be of clinical relevance given the current body of evidence showing bone healing under shear strains of up to 25%. The greatest transverse shear was observed under bending loads in all fine-wire frames, approaching 30% (29% ± 1.9). This was reduced to 8% (±0.2) by incorporation of sagittal plane half-pins and 7% (±0.2) in all half-pin frames (mean difference, -13.2% and -14.0%, 95% CI, -16.6% to 9.7% and -17.5% to -10.6%, both p < 0.001). CONCLUSIONS: Appropriate use of half-pins may reduce levels of shear strain on physiologic loading of circular frames without otherwise altering the fracture site mechanical environment at levels likely to be clinically important. Given the limitations of a biomechanical study using a symmetric and uniform synthetic bone model, further clinical studies are needed to confirm these conclusions in vivo. CLINICAL RELEVANCE: The findings of this study add to the overall understanding of the mechanics of circular frame fixation and, if replicated in the clinical setting, may be applied to the preoperative planning of frame treatment, particularly in unstable fractures or bone transport where control of shear strain is a priority.


Assuntos
Pinos Ortopédicos , Fios Ortopédicos , Fixadores Externos , Consolidação da Fratura , Fraturas Ósseas/cirurgia , Técnica de Ilizarov/instrumentação , Fenômenos Biomecânicos , Substitutos Ósseos , Fraturas Ósseas/fisiopatologia , Modelos Anatômicos , Desenho de Prótese , Estresse Mecânico
12.
Cochrane Database Syst Rev ; 8: CD006583, 2015 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-26329306

RESUMO

BACKGROUND: Laparoscopy is a common procedure in many surgical specialities. Complications arising from laparoscopy are often related to initial entry into the abdomen. Life-threatening complications include injury to viscera e.g. the bowel or bladder, or to vasculature e.g. major abdominal and anterior abdominal wall vessels. Minor complications can also occur, such as postoperative wound infection, subcutaneous emphysema, and extraperitoneal insufflation. There is no clear consensus as to the optimal method of laparoscopic entry into the peritoneal cavity. OBJECTIVES: To evaluate the benefits and risks of different laparoscopic entry techniques in gynaecological and non-gynaecological surgery. SEARCH METHODS: This updated review has drawn on the search strategy developed by the Cochrane Menstrual Disorders and Subfertility Group. In addition, MEDLINE, EMBASE, CENTRAL and PsycINFO were searched through to September 2014. SELECTION CRITERIA: We included randomised controlled trials (RCTs) in which one laparoscopic entry technique was compared with another. DATA COLLECTION AND ANALYSIS: Two authors independently selected studies, assessed risk of bias, and extracted data. We expressed findings as Peto odds ratios (Peto ORs) with 95% confidence intervals (CIs). We assessed statistical heterogeneity using the I² statistic. We assessed the overall quality of evidence for the main comparisons using GRADE methods. MAIN RESULTS: The review included 46 RCTs including three multi-arm trials (7389 participants) and evaluated 13 laparoscopic entry techniques. Overall there was no evidence of advantage using any single technique for preventing major vascular or visceral complications. The evidence was generally of very low quality; the main limitations were imprecision and poor reporting of study methods. Open-entry versus closed-entry There was no evidence of a difference between the groups for vascular (Peto OR 0.14, 95% CI 0.00 to 6.82, three RCTs, n = 795, I(2) = n/a; very low quality evidence) or visceral injury (Peto OR 0.61, 95% CI 0.06 to 6.08, three RCTs, n = 795, I(2) = 0%; very low quality evidence). There was a lower risk of failed entry in the open-entry group (Peto OR 0.16, 95% CI 0.04 to 0.63, n = 665, two RCTs, I(2) = 0%; very low quality evidence). This suggests that for every 1000 patients operated on, 31 patients in the closed-entry group will have failed entry compared to between 1 to 20 patients in the open-entry group. No events were reported in any of the studies for mortality, gas embolism or solid organ injury. Direct trocar versus Veress needle entry There was a lower risk of vascular injury in the direct trocar group (Peto OR 0.13, 95% CI 0.03 to 0.66, five RCTs, n = 1522, I(2) = 0%; low quality evidence) and failed entry (Peto OR 0.21, 95% CI 0.14 to 0.30, seven RCTs, n = 3104; I ²= 0%; moderate quality evidence). This suggests that for every 1000 patients operated on, 8 patients in the Veress needle group will experience vascular injury compared to between 0 to 5 patients in the direct trocar group; and that 64 patients in the Veress needle group will experience failed entry compared to between 10 to 20 patients in the direct trocar group. The vascular injury significance is sensitive to choice of statistical analysis and may be unreliable. There was no evidence of a difference between the groups for visceral (Peto OR 1.02, 95% CI 0.06 to 16.24, four RCTs, n = 1438, I(2) = 49%; very low quality evidence) or solid organ injury (Peto OR 0.16, 95% Cl 0.01 to 2.53, two RCTs, n = 998, I(2) = n/a; very low quality evidence). No events were recorded for mortality or gas embolism. Direct vision entry versus Veress needle entry There was no evidence of a difference between the groups in the rates of visceral injury (Peto OR 0.15, 95% CI 0.01 to 2.34, one RCT, n = 194; very low quality evidence). Other primary outcomes were not reported. Direct vision entry versus open-entry There was no evidence of a difference between the groups in the rates of visceral injury (Peto OR 0.13, 95% CI 0.00 to 6.50, two RCTs, n = 392; low quality evidence), solid organ injury (Peto OR 6.16, 95% CI 0.12 to 316.67, one RCT, n = 60, I(2) = n/a; very low quality evidence), or failed entry (Peto OR 0.40, 95% CI 0.04 to 4.09, one RCT, n = 60; low quality evidence). Vascular injury was reported, however no events occurred. Our other primary outcomes were not reported. Radially expanding (STEP) trocars versus non-expanding trocars There was no evidence of a difference between the groups for vascular injury (Peto OR 0.24, 95% Cl 0.05 to 1.21, two RCTs, n = 331, I(2) = 0%; low quality evidence), visceral injury (Peto OR 0.13, 95% CI 0.00 to 6.37, two RCTs, n = 331, I(2) = n/a; low quality evidence), or solid organ injury (Peto OR 1.05, 95% CI 0.07 to 16.91, one RCT, n = 244; very low quality evidence). Other primary outcomes were not reported. Comparisons of other laparoscopic entry techniquesThere was a higher risk of failed entry in the group in which the abdominal wall was lifted before Veress needle insertion than in the not-lifted group (Peto OR 4.44, 95% CI 2.16 to 9.13, one RCT, n = 150; very low quality evidence). There was no evidence of a difference between the groups in rates of visceral injury or extraperitoneal insufflation. The studies had small numbers and excluded many patients with previous abdominal surgery, and women with a raised body mass index. These patients may have unusually high complication rates. AUTHORS' CONCLUSIONS: Overall, there is insufficient evidence to recommend one laparoscopic entry technique over another.An open-entry technique is associated with a reduction in failed entry when compared to a closed-entry technique, with no evidence of a difference in the incidence of visceral or vascular injury.An advantage of direct trocar entry over Veress needle entry was noted for failed entry and vascular injury. The evidence was generally of very low quality with small numbers of participants in most studies; our findings should be interpreted with caution.


Assuntos
Parede Abdominal , Procedimentos Cirúrgicos em Ginecologia/efeitos adversos , Laparoscopia/efeitos adversos , Vasos Sanguíneos/lesões , Feminino , Procedimentos Cirúrgicos em Ginecologia/métodos , Humanos , Intestinos/lesões , Complicações Intraoperatórias/prevenção & controle , Laparoscopia/métodos , Cavidade Peritoneal , Ensaios Clínicos Controlados Aleatórios como Assunto , Bexiga Urinária/lesões
13.
Proc Natl Acad Sci U S A ; 108(1): 179-84, 2011 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-21173232

RESUMO

The intestinal epithelium is maintained by a population of rapidly cycling (Lgr5(+)) intestinal stem cells (ISCs). It has been postulated, however, that slowly cycling ISCs must also be present in the intestine to protect the genome from accumulating deleterious mutations and to allow for a response to tissue injury. Here, we identify a subpopulation of slowly cycling ISCs marked by mouse telomerase reverse transcriptase (mTert) expression that can give rise to Lgr5(+) cells. mTert-expressing cells distribute in a pattern along the crypt-villus axis similar to long-term label-retaining cells (LRCs) and are resistant to tissue injury. Lineage-tracing studies demonstrate that mTert(+) cells give rise to all differentiated intestinal cell types, persist long term, and contribute to the regenerative response following injury. Consistent with other highly regenerative tissues, our results demonstrate that a slowly cycling stem cell population exists within the intestine.


Assuntos
Mucosa Intestinal/citologia , Células-Tronco Multipotentes/metabolismo , Telomerase/metabolismo , Animais , Linhagem da Célula/fisiologia , Citometria de Fluxo , Proteínas de Fluorescência Verde/metabolismo , Imuno-Histoquímica , Camundongos , Microscopia de Fluorescência , Células-Tronco Multipotentes/citologia , Receptores Acoplados a Proteínas G/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa
14.
Artigo em Inglês | MEDLINE | ID: mdl-38499253

RESUMO

PURPOSE: Dose-escalated radiation therapy is associated with better biochemical control at the expense of toxicity. Stereotactic body radiation therapy (SBRT) with dose escalation to the dominant intraprostatic lesion (DIL) provides a logical approach to improve outcomes in high-risk disease while limiting toxicity. This study evaluated the toxicity and quality of life (QoL) with CyberKnife-based SBRT and simultaneous integrated boost in localized prostate cancer. METHODS AND MATERIALS: Eligible participants included newly diagnosed, biopsy-proven unfavorable intermediate- to high-risk localized prostate cancer (at least 1 of the following: Gleason ≥4+3, magnetic resonance imaging(MRI)-defined T3a N0, prostate-specific antigen ≥20) with up to 2 MRI-identified DILs. Participants received 36.25 Gy in 5 fractions on alternative days with a simultaneous boost to DIL up to 47.5 Gy as allowed by organ-at-risk constraints delivered by CyberKnife. All participants received androgen deprivation therapy. The primary outcome measure was acute grade 2+ genitourinary toxicity. Acute and late genitourinary and gastrointestinal toxicity using Radiation Therapy Oncology Group scoring, biochemical parameters, International Prostate Symptom Score, International Index of Erectile Function 5, and EQ-5D QoL outcomes were assessed. RESULTS: Between 2013 and 2023, 20 participants were enrolled with a median follow-up of 30 months. The median D95 dose to DIL was 47.43 Gy. Cumulative acute grade 2+ genitourinary and gastrointestinal toxicity were 25% and 30%, respectively. One patient developed acute grade 3 genitourinary toxicity (5%). There is no late grade 3 genitourinary or gastrointestinal toxicity to date. International Prostate Symptom Score and urinary QoL scores recovered to baseline by 6 months. Patient-reported outcomes showed no significant change in EQ-5D QoL scores at 12 weeks and 1 year. There are no cases of biochemical relapse reported to date. CONCLUSIONS: CyberKnife SBRT-delivered dose of 36.25 Gy to the prostate with a simultaneous integrated boost up to 47.5 Gy is well tolerated. Acute and late genitourinary and gastrointestinal toxicity rates are comparable to other contemporary SBRT trials and series with focal boost.

15.
Vaccine ; 41(2): 304-314, 2023 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-36587961

RESUMO

All seasonal influenza vaccines for 2021-2022 in the US were quadrivalent and the market continues to be dominated by intramuscular delivery of non-adjuvanted, virion-derived antigens grown in chicken eggs. Up to four new egg-adapted production influenza vaccine strains must be generated each year. The introduction in 2012 of Flucelvax®, which is grown in mammalian suspension cell culture and uses vaccine production strains without adaptive mutations for efficient growth in eggs, represented a major advance in vaccine production technology. Here we demonstrate that Flucelvax can be reformulated and combined with a liposomal adjuvant containing QS-21 (Verndari Adjuvant System 1.1, VAS1.1) or QS-21 and 3D-PHAD (VAS1.2) for intradermal administration using a painless skin patch, VaxiPatch™. VAS1.2 is similar to AS01B, the adjuvant system used in Shingrix® and Mosquirix™. We show that Flucelvax, when reformulated and concentrated using tangential flow filtration (TFF), maintains hemagglutination and single radial immunodiffusion (SRID) potency. Loading the reformulated Flucelvax material onto VaxiPatch arrays conferred high levels of resistance to heat stress and room temperature stability. TFF enriched vaccine antigens were combined with VAS1.1 or VAS1.2 and dispensed in 10nL drops into the pockets of 36 (total 360 nL) stainless steel microneedles arranged in a microarray 1.2 cm in diameter. Using VaxiPatch delivery of 2 µg of antigen, we demonstrated intramusuclar-comparable IgG and hemagglutination inhibition (HAI) immune responses in Sprague Dawley® rats. With addition of VAS1.2, antigen-specific IgG titers were increased as much as 68-fold (47-fold for VAS1.1) with improvements in seroconversion for three of four strains (all four were improved by VAS1.1). TFF-reformulated antigens combined with VAS1.1 or VAS1.2 and delivered by VaxiPatch showed only minor skin reactogenicity after 1 h and no skin reactogenicity after 24 h. These data indicate that VaxiPatch and the VAS system have the potential to be transformative for vaccine delivery.


Assuntos
Vacinas contra Influenza , Influenza Humana , Ratos , Animais , Humanos , Estações do Ano , Ratos Sprague-Dawley , Influenza Humana/prevenção & controle , Adjuvantes Imunológicos , Vacinação , Testes de Inibição da Hemaglutinação , Vacinas Combinadas , Anticorpos Antivirais , Imunoglobulina G , Injeções Intradérmicas , Mamíferos
16.
Respirol Case Rep ; 11(12): e01235, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38028563

RESUMO

N,N'-dimethyl-4,4'bipyridinium dichloride (Paraquat) is a potent herbicide used widely in agriculture. We report the effects of an ingestion of paraquat by a 28 year old male with cystic fibrosis and the diagnostic and management challenges this posed in both the acute and longer term setting. We describe the effects of direct paraquat toxicity on the lung tissue secondary to aspiration and review the long-term sequelae of paraquat, namely osteonecrosis. Our case is the first to describe osteonecrosis of the knee in the context of paraquat toxicity. Survival following ingestion remains poor with a high associated mortality. However, timely treatment with NAC and immunosuppression may impact on survival. In those patients who do survive the acute phase post ingestion, follow-up over years may be required to detect the long-term effects of paraquat on bone health.

17.
JCI Insight ; 8(21)2023 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-37788104

RESUMO

MTORC1 integrates signaling from the immune microenvironment to regulate T cell activation, differentiation, and function. TSC2 in the tuberous sclerosis complex tightly regulates mTORC1 activation. CD8+ T cells lacking TSC2 have constitutively enhanced mTORC1 activity and generate robust effector T cells; however, sustained mTORC1 activation prevents generation of long-lived memory CD8+ T cells. Here we show that manipulating TSC2 at Ser1365 potently regulated activated but not basal mTORC1 signaling in CD8+ T cells. Unlike nonstimulated TSC2-KO cells, CD8+ T cells expressing a phosphosilencing mutant TSC2-S1365A (TSC2-SA) retained normal basal mTORC1 activity. PKC and T cell receptor (TCR) stimulation induced TSC2 S1365 phosphorylation, and preventing this with the SA mutation markedly increased mTORC1 activation and T cell effector function. Consequently, SA CD8+ T cells displayed greater effector responses while retaining their capacity to become long-lived memory T cells. SA CD8+ T cells also displayed enhanced effector function under hypoxic and acidic conditions. In murine and human solid-tumor models, SA CD8+ T cells used as adoptive cell therapy displayed greater antitumor immunity than WT CD8+ T cells. These findings reveal an upstream mechanism to regulate mTORC1 activity in T cells. The TSC2-SA mutation enhanced both T cell effector function and long-term persistence/memory formation, supporting an approach to engineer better CAR-T cells for treating cancer.


Assuntos
Esclerose Tuberosa , Camundongos , Humanos , Animais , Alvo Mecanístico do Complexo 1 de Rapamicina , Linfócitos T CD8-Positivos , Mutação , Diferenciação Celular , Microambiente Tumoral
18.
Milbank Q ; 90(3): 484-515, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22985279

RESUMO

CONTEXT: Many primary care practices are moving toward the patient-centered medical home (PCMH) model and increasingly are offering payment incentives linked to PCMH changes. Despite widespread acceptance of general PCMH concepts, there is still a pressing need to examine carefully and critically what transformation means for primary care practices and their patients and the experience of undergoing such change in a practice. METHODS: We used a qualitative case study approach to explore the underlying dynamics of change at five practices participating in PCMH transformation efforts linked to payment reform. The evaluation consisted of structured site visits, interviews, observations, and artifact reviews followed by a structured review of transcripts and documents for patterns, themes, and insights related to PCMH implementation. FINDINGS: We describe both the detailed components of each practice's transformation efforts and a grounded taxonomy of eight insights stemming from the experiences of these medical homes. We identified specific contextual factors related to wide variations in change tactics. We also observed widely varying approaches to catalyzing change using (or not) external consultants, specific challenges regarding health information technology implementation, team and staff role restructuring, compensation, and change fatigue, and several unexpected potential confounders or alternative explanations for practice success. CONCLUSIONS: Our evaluation affirms the value and necessity of qualitative methods for understanding primary care practice transformation, and it should encourage ongoing and future pilots to include assessments of the PCMH change process beyond clinical markers and claims data. The results raise insights into the heterogeneity of medical home transformation, the central but complex role of payment reform in creating a space for change, the ability of small practices to achieve substantial change in a short time period, and the challenges of sustaining it.


Assuntos
Assistência Centrada no Paciente/normas , Garantia da Qualidade dos Cuidados de Saúde , Reembolso de Incentivo , Humanos , Massachusetts , Informática Médica , Estudos de Casos Organizacionais , Inovação Organizacional , Equipe de Assistência ao Paciente/organização & administração , Assistência Centrada no Paciente/organização & administração , Papel do Médico , Projetos Piloto , Qualidade da Assistência à Saúde , Encaminhamento e Consulta/estatística & dados numéricos , Reembolso de Incentivo/organização & administração , Reembolso de Incentivo/normas
19.
Proc Natl Acad Sci U S A ; 105(30): 10420-5, 2008 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-18650388

RESUMO

Stem cells hold great promise for regenerative medicine, but remain elusive in many tissues in part because universal markers of "stemness" have not been identified. The ribonucleoprotein complex telomerase catalyzes the extension of chromosome ends, and its expression is associated with failure of cells to undergo cellular senescence. Because such resistance to senescence is a common characteristic of many stem cells, we hypothesized that telomerase expression may provide a selective biomarker for stem cells in multiple tissues. In fact, telomerase expression has been demonstrated within hematopoietic stem cells. We therefore generated mouse telomerase reverse transcriptase (mTert)-GFP-transgenic mice and assayed the ability of mTert-driven GFP to mark tissue stem cells in testis, bone marrow (BM), and intestine. mTert-GFP mice were generated by using a two-step embryonic stem cell-based strategy, which enabled primary and secondary screening of stably transfected clones before blastocyst injection, greatly increasing the probability of obtaining mTert reporter mice with physiologically appropriate regulation of GFP expression. Analysis of adult mice showed that GFP is expressed in differentiating male germ cells, is enriched among BM-derived hematopoietic stem cells, and specifically marks long-term BrdU-retaining intestinal crypt cells. In addition, telomerase-expressing GFP(+) BM cells showed long-term, serial, multilineage BM reconstitution, fulfilling the functional definition of hematopoietic stem cells. Together, these data provide direct evidence that mTert-GFP expression marks progenitor cells in blood and small intestine, validating these mice as a useful tool for the prospective identification, isolation, and functional characterization of progenitor/stem cells from multiple tissues.


Assuntos
Células-Tronco Embrionárias/citologia , Técnicas Genéticas , Proteínas de Fluorescência Verde/metabolismo , Células-Tronco/citologia , Telomerase/metabolismo , Animais , Biomarcadores/metabolismo , Medula Óssea/metabolismo , Separação Celular , Mucosa Intestinal/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Fenótipo , Testículo/metabolismo
20.
Strategies Trauma Limb Reconstr ; 16(3): 138-143, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35111252

RESUMO

BACKGROUND: The Ilizarov method and fixator are clinically recognised for the treatment of fractures, limb salvage and deformity correction. There have been extensive studies determining the basic mechanism for fracture healing using this technique. It is generally accepted that circular frames optimise the mechanical environment by reducing shear strain across the fracture while maintaining axial micromotion so as to promote fracture healing. There have been several new hexapod-type frames introduced into the market over the past 20 years with little comparative research into their biomechanical properties and resultant effects on the fracture environment. QUESTIONS/PURPOSES: To investigate the biomechanical behaviours of the TrueLok-Hex (TL-HEX) and Taylor spatial frame (TSF) hexapod-type circular external fixators with comparison to traditional Ilizarov-type (TL-Ilizarov and TSF-Ilizarov) constructs and potential performance in vivo. METHODS: Testing was performed on standardised four-ring TSF and TL-HEX constructs matched by identical frames using Ilizarov threaded rod constructs for each set of components. All frames were tested under physiological levels of axial, bending and torsional loading. Load-deformation properties for each construct under each mode of loading were calculated and analysed statistically using ANOVA. RESULTS: Under axial loading, the Ilizarov construct utilising TL-HEX components demonstrated the greatest rigidity followed by the Ilizarov construct using TSF components. Under bending loads, the difference in rigidity between constructs was similar but less marked. Under torsional loading, both hexapod frames were seen to be significantly more rigid than the Ilizarov constructs. Overall deformation around neutral loading was much higher in the TSF frame due to an observed significant "toe-in" laxity in the strut universal joints. The remaining deformation of both hexapod frames was similar with a higher level of TL-HEX rigidity in axial loading and a higher level of TSF rigidity in bending and torsion. CONCLUSION: In conclusion, both hexapod frame constructs were less rigid under axial loading but more rigid under bending and torsional loads than their comparative Ilizarov constructs. As a result of their Cardan universal joints, the TSF demonstrated greater overall planar strain due to the observed "toe-in" laxity around neutral loading while the TL-HEX, with ball-and-socket universal joints, demonstrated a minimal level of laxity. Beyond the initial deformation due to the preloaded laxity, both hexapod frames responded to loading in a similar manner. There were significant differences in the frames' mechanical behaviour under different loading conditions but further research is required to determine whether these translate in vivo into clinical significance. HOW TO CITE THIS ARTICLE: Fenton C, Henderson D, Samchukov M, et al. Comparative Stiffness Characteristics of Ilizarov- and Hexapod-type External Frame Constructs. Strategies Trauma Limb Reconstr 2021;16(3):138-143.

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