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2.
Eur J Neurol ; 24(8): 1071-1076, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-28636179

RESUMEN

BACKGROUND AND PURPOSE: Trial discontinuation and non-publication represent major sources of research waste in clinical medicine. No previous studies have investigated non-dissemination bias in clinical trials of neurodegenerative diseases. METHODS: ClinicalTrials.gov was searched for all randomized, interventional, phase II-IV trials that were registered between 1 January 2000 and 31 December 2009 and included adults with Alzheimer's disease, motor neurone disease, multiple sclerosis or Parkinson's disease. Publications from these trials were identified by extensive online searching and contact with authors, and multiple logistic regression analysis was performed to identify characteristics associated with trial discontinuation and non-publication. RESULTS: In all, 362 eligible trials were identified, of which 12% (42/362) were discontinued. 28% (91/320) of completed trials remained unpublished after 5 years. Trial discontinuation was independently associated with number of patients (P = 0.015; more likely in trials with ≤100 patients; odds ratio 2.65, 95% confidence interval 1.21-5.78) and phase of trial (P = 0.009; more likely in phase IV than phase III trials; odds ratio 3.90, 95% confidence interval 1.41-10.83). Trial non-publication was independently associated with blinding status (P = 0.005; more likely in single-blind than double-blind trials; odds ratio 5.63, 95% confidence interval 1.70-18.71), number of centres (P = 0.010; more likely in single-centre than multi-centre trials; odds ratio 2.49, 95% confidence interval 1.25-4.99), phase of trial (P = 0.041; more likely in phase II than phase IV trials; odds ratio 2.88, 95% confidence interval 1.04-7.93) and sponsor category (P = 0.001; more likely in industry-sponsored than university-sponsored trials; odds ratio 5.05, 95% confidence interval 1.87-13.63). CONCLUSIONS: There is evidence of non-dissemination bias in randomized trials of interventions for neurodegenerative diseases. Associations with trial discontinuation and non-publication were similar to findings in other diseases. These biases may distort the therapeutic information available to inform clinical practice.


Asunto(s)
Ensayos Clínicos como Asunto , Difusión de la Información , Enfermedades Neurodegenerativas/tratamiento farmacológico , Edición , Estudios Transversales , Bases de Datos Factuales , Humanos , Proyectos de Investigación
4.
Lung Cancer ; 159: 18-26, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-34303276

RESUMEN

INTRODUCTION: Acquired resistance to TKI is an important unmet need in the management of EGFR mutated lung cancer. Recent clinical trial IMPower150 suggested that combination approach with VEGF inhibitor, check point inhibitor immunotherapy and platinum-based chemotherapy was effective in oncogene driven lung cancer. The current trial examined the efficacy of a modified regimen in an EGFR mutated cohort. METHODS: An open-labelled, single arm, phase II study was conducted in patients with EGFR mutated NSCLC who had progressed on at least one EGFR TKI. For those with T790M mutation, radiological progression on osimertinib was required for enrolment. Patients were treated with combination atezolizumab (1200 mg), bevacizumab (7.5 mg/kg), pemetrexed (500 mg/m2) and carboplatin (AUC 5) given once every 3 weeks until progression. RESULTS: Forty patients were enrolled. Median age was 62 (range 45-76) years. More than one half (23/40, 57.5%) had progressed on osimertinib. PD-L1 expression was < 1% in 52.5%. Median follow-up time was 17.8 months. ORR was 62.5%. Median PFS was 9.4 months (95% CI: 7.6 - 12.1). One year OS was 72.5% (95% CI: 0.56-0.83). Treatment related grade 3 or above adverse events (AE) occurred in 37.5% (15/40). Immune-related AE occurred in 32.5% (13/40) patients. Quality of life measures of function and symptoms did not change significantly throughout the course of treatments. Post-trial rechallenge with EGFR TKI containing regimen resulted in PFS of 5.8 months (95% CI 3.9-10.0 months). CONCLUSION: Combination approach of atezolizumab, bevacizumab, pemetrexed and carboplatin achieved promising efficacy in metastatic EGFR mutated NSCLC after TKI failure. The results were comparable with taxane based regimen of IMPower150 while toxicity profile was improved.


Asunto(s)
Receptores ErbB , Neoplasias Pulmonares , Anciano , Anticuerpos Monoclonales Humanizados , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Bevacizumab/uso terapéutico , Carboplatino/uso terapéutico , Receptores ErbB/genética , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Persona de Mediana Edad , Mutación , Pemetrexed/uso terapéutico , Inhibidores de Proteínas Quinasas/uso terapéutico , Calidad de Vida
5.
Hong Kong Med J ; 15(4): 255-61, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19652231

RESUMEN

OBJECTIVE: To study the epidemiology of Candida bloodstream infection in the Intensive Care Unit. DESIGN: Retrospective study. SETTING: A 22-bed, mixed medical and surgical Intensive Care Unit of a 1400-bed university teaching hospital in Hong Kong. PATIENTS: All adult patients (>18 years) who had at least one blood culture positive for Candida. RESULTS: During the 9 years of the study period, there were 128 patients with episodes of candidaemia (point prevalence, 9.6 per 1000 Intensive Care Unit admissions), 72 entailed albicans candidaemia and 56 non-albicans candidaemia. Albicans was still the predominant species, but the incidence of tropicalis was increasing. The median lengths of hospital and Intensive Care Unit stays prior to taking of the culture revealing candidaemia were 15 and 6 days, respectively. In all, 61% of patients did not have Candida colonisation within 2 weeks of their candidaemia. The main anti-fungal agents used were fluconazole and amphotericin B, but only 89 (70%) of the patients received appropriate anti-fungal treatment. Intensive Care Unit and hospital mortalities were 70% and 78%, respectively. Patients who did not receive appropriate treatment within 3 days had a worse outcome than those who did. CONCLUSIONS: Our data showed a high point prevalence of candidaemia in the Intensive Care Unit. Albicans was still the predominant species. Candidaemia occurred early during Intensive Care Unit stay, and a significant proportion of patients did not have prior fungal colonisation. Candidaemia in the Intensive Care Unit was associated with high morbidity and mortality. Many patients did not receive appropriately early anti-fungal therapy, and endured higher mortality than in the remainder.


Asunto(s)
Antifúngicos/uso terapéutico , Bacteriemia/tratamiento farmacológico , Bacteriemia/epidemiología , Candidiasis/tratamiento farmacológico , Candidiasis/epidemiología , Infección Hospitalaria/tratamiento farmacológico , Infección Hospitalaria/epidemiología , Unidades de Cuidados Intensivos , Adulto , Anciano , Bacteriemia/microbiología , Candidiasis/microbiología , Distribución de Chi-Cuadrado , Infección Hospitalaria/microbiología , Femenino , Hong Kong/epidemiología , Humanos , Incidencia , Tiempo de Internación/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Retrospectivos , Factores de Riesgo , Estadísticas no Paramétricas
6.
AJNR Am J Neuroradiol ; 40(3): 412-417, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30733252

RESUMEN

BACKGROUND AND PURPOSE: Co-occurrence of local anisotropic gradient orientations (COLLAGE) is a recently developed radiomic (computer extracted) feature that captures entropy (measures the degree of disorder) in pixel-level edge directions and was previously shown to distinguish predominant cerebral radiation necrosis from recurrent tumor on gadolinium-contrast T1WI. In this work, we sought to investigate whether COLLAGE measurements from posttreatment gadolinium-contrast T1WI could distinguish varying extents of cerebral radiation necrosis and recurrent tumor classes in a lesion across primary and metastatic brain tumors. MATERIALS AND METHODS: On a total of 75 gadolinium-contrast T1WI studies obtained from patients with primary and metastatic brain tumors and nasopharyngeal carcinoma, the extent of cerebral radiation necrosis and recurrent tumor in every brain lesion was histopathologically defined by an expert neuropathologist as the following: 1) "pure" cerebral radiation necrosis; 2) "mixed" pathology with coexistence of cerebral radiation necrosis and recurrent tumors; 3) "predominant" (>80%) cerebral radiation necrosis; 4) predominant (>80%) recurrent tumor; and 5) pure tumor. COLLAGE features were extracted from the expert-annotated ROIs on MR imaging. Statistical comparisons of COLLAGE measurements using first-order statistics were performed across pure, mixed, and predominant pathologies of cerebral radiation necrosis and recurrent tumor using the Wilcoxon rank sum test. RESULTS: COLLAGE features exhibited decreased skewness for patients with pure (0.15 ± 0.12) and predominant cerebral radiation necrosis (0.25 ± 0.09) and were statistically significantly different (P < .05) from those in patients with predominant recurrent tumors, which had highly skewed (0.42 ± 0.21) COLLAGE values. COLLAGE values for the mixed pathology studies were found to lie between predominant cerebral radiation necrosis and recurrent tumor categories. CONCLUSIONS: With additional independent multisite validation, COLLAGE measurements might enable noninvasive characterization of the degree of recurrent tumor or cerebral radiation necrosis in gadolinium-contrast T1WI of posttreatment lesions.


Asunto(s)
Neoplasias Encefálicas/diagnóstico por imagen , Interpretación de Imagen Asistida por Computador/métodos , Recurrencia Local de Neoplasia/diagnóstico por imagen , Traumatismos por Radiación/diagnóstico por imagen , Adulto , Anciano , Neoplasias Encefálicas/patología , Diagnóstico Diferencial , Femenino , Gadolinio , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Necrosis/diagnóstico por imagen , Traumatismos por Radiación/patología
7.
Clin Oncol (R Coll Radiol) ; 31(8): 589-594, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31230834

RESUMEN

Cancer is the most common cause of mortality worldwide. Although recent advances of multiple modality cancer management have significantly improved the cure and control rates, a significant proportion of patients are still refractory to the standard and available treatments. Early initiation of palliative care can reduce cancer suffering, improve health-related quality of life and possibly prolong survival. It also allows patients and their caretakers to perceive the trajectory of their cancer, so that better and advanced care planning can be contemplated and implemented. The traditional beliefs and perceptions of cancer also differ significantly between the East and the West, which may also affect the preferential approach to palliative care. This review provides an overview of palliative care services in Hong Kong, as compared with other parts of the world. In addition, we shall also explore how cancer perceptions affect the decision-making on palliative care.


Asunto(s)
Neoplasias/terapia , Cuidados Paliativos/métodos , Calidad de Vida/psicología , Asia Oriental , Hong Kong , Humanos
9.
Plast Reconstr Surg Glob Open ; 3(7): e473, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26301162

RESUMEN

BACKGROUND: Prosthetic breast reconstruction is generally considered contraindicated after previous breast irradiation. As a result, patients undergoing a salvage mastectomy for recurrent breast cancer or "risk-reducing" mastectomies after previous conservative surgery and radiotherapy (CS + RT) are usually offered autologous breast reconstruction. However, not all such patients are suitable candidates for a major flap reconstruction. The purpose of this study is to review our results of immediate 2-stage prosthetic breast reconstruction after CS + RT. METHODS: A retrospective review was undertaken for 671 consecutive patients with prosthetic-only breast reconstruction performed by a single surgeon over a 12.5-year period. Twenty-two patients who qualified for the criteria were audited. Outcomes examined include complications, loss of tissue expander or implant, revisional surgery, and aesthetic result. RESULTS: Twenty-two patients underwent 33 mastectomies and immediate 2-stage breast reconstructions after previous CS + RT (15 for recurrent cancer and seven "risk-reduction") and 11 contralateral risk-reducing mastectomies. One patient died due to extensive metastatic disease. There was no reconstruction failure. The average breast implant size was 491.7 g (range 220 -685g). Seroma was the most common complication and occurred in 3 of 22 patients (13.6%) after stage 1 and 3 of 21 patients (14.3%) after stage 2 reconstruction. The revisional surgery rate was 28.6%. Aesthetic result was rated as excellent in 9.5%, good in 76.2%, and fair in 14.3%. CONCLUSIONS: For selected patients, immediate 2-stage prosthetic breast reconstruction can be performed successfully after a salvage mastectomy subsequent to a recurrence after CS + RT.

10.
J Thorac Cardiovasc Surg ; 104(2): 395-400, 1992 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-1495302

RESUMEN

Leakage, tumor recurrence, and stricture formation at the anastomosis are serious problems after esophagectomy for cancer of the esophagus or cardia. Because the prevalence of these postoperative complications may be affected by whether an anastomosis is made in the neck or in the chest, a comparison was made between anastomoses made at these two sites. During a period of some 7 years, we studied prospectively 411 patients who underwent resection for cancer of the esophagus or cardia and, after immediate reconstruction, had an anastomosis made in the neck or chest. The anastomotic leak rate for the neck anastomosis group was 4.3% and for the chest anastomosis group, 3.7% (p = not significant). The difference between leak rates of anastomoses fashioned by hand-sewn (5.0%) or stapled (3.0%) techniques was also not significant. The median upper resection margins in the neck and chest anastomosis groups were 4.5 cm and 3.5 cm, respectively. The corresponding rates of anastomotic tumor recurrence were 6.1% and 8.1% (p = not significant). The prevalence of benign stricture formation was significantly higher in the chest anastomosis group (19.2%) than in the neck anastomosis group (9.0%) (p = 0.002). This difference was a reflection of a significantly increased prevalence of stricture formation when an anastomosis was made by the stapler technique than with the hand-sewn method, and whereas most of the anastomoses in the neck were hand sewn (90%) the majority of those in the chest were stapled (80%). There were thus no statistically significant differences between the sites in terms of anastomotic leak and tumor recurrence rates, and the higher stricture rate in the chest anastomosis group was the result of more stapled anastomoses.


Asunto(s)
Anastomosis Quirúrgica/métodos , Carcinoma de Células Escamosas/cirugía , Neoplasias Esofágicas/cirugía , Esofagectomía/efectos adversos , Recurrencia Local de Neoplasia/epidemiología , Dehiscencia de la Herida Operatoria/epidemiología , Constricción Patológica/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Cuello , Prevalencia , Engrapadoras Quirúrgicas , Técnicas de Sutura , Tórax
11.
Urol Clin North Am ; 18(2): 327-37, 1991 May.
Artículo en Inglés | MEDLINE | ID: mdl-2017814

RESUMEN

Routine incontinence in the woman is defined as stress urinary incontinence associated with a hypermobile urethra and bladder neck that has not been subjected to an operative procedure. Although urgency and occasional urgency incontinence may accompany the symptoms of stress incontinence, they are not a significant component of the patient's complaints. Regardless of technique, the goal common to all procedures designed to cure stress urinary incontinence is to immobilize and support the hypermobile urethra. The support provided by the operation creates a foundation on which the urethra can be compressed shut during abdominal straining. The operation of choice is determined by its ability to provide this strong foundation over a long period of time. Although numerous reports have been published outlining the results of bladder neck suspension, most authors have not utilized objective long-term follow-up when assessing cure rates. We prefer either the Burch colpourethropexy or the modified Pereyra needle bladder neck suspension because the vaginal wall is firmly supportive without interfering with the delicate mechanisms of the urethra.


Asunto(s)
Incontinencia Urinaria de Esfuerzo/cirugía , Femenino , Humanos , Procedimientos Quirúrgicos Operativos/métodos , Incontinencia Urinaria de Esfuerzo/diagnóstico
12.
J Biomech ; 25(10): 1227-31, 1992 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1400523

RESUMEN

A comprehensive calibration and error analysis of a video dimension analyser (VDA) system was carried out to determine the effects of various parameters relevant to actual test conditions on the characteristics of the system. The parameters considered were: (1) varying distances or angles between the test specimen and the camera; (2) refractive effects of glass tank and physiologic solutions; and (3) dynamic response of the VDA system. The error analysis shows that, at low strain levels, the strain computed by the VDA is sensitive to camera placement and orientation as well as the media through which the object is observed. Very large errors can occur at small nominal strains, depending on the system parameters (e.g. 80% error at 1% nominal strain for one set of parameters). At higher strain levels, the sensitivity of the system is reduced, and the strain computed by the VDA system approaches the nominal strain (10% error at 10% nominal strain).


Asunto(s)
Estrés Mecánico , Grabación en Video/métodos , Calibración , Tejido Conectivo/fisiología , Humanos , Ligamentos/fisiología
13.
J Biomech ; 26(1): 9-17, 1993 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-8423173

RESUMEN

There is at present no information on how the viscoelastic properties of bone-ligament-bone complexes change during maturation. Changes in the static and the cyclic relaxation behaviours of rabbit bone-medial-collateral-ligament-bone complexes at 3, 6, 9 and 12 months of age are described. These ages cover maturation and initial ageing of this complex. The specimens were subject to 30 cycles of uniaxial tension between zero and 0.68 mm extension at 10 mm min-1. Immediately after the cyclic test, the specimens were held at a constant 0.68 mm extension for 1200 s. The results showed that in both the cyclic and the static tests, specimens from 3-month-old animals relaxed significantly more than specimens at 6, 9 or 12 months of age, whereas those 6, 9 and 12 months old were not significantly different from each other. When the results of the cyclic tests were compared to those of the static tests, cyclic relaxation was higher than static relaxation for each of the 6-, 9- and 12-month-old specimens. For specimens 3 months of age, the opposite was observed. An explanation is offered whereby the total relaxation is suggested to be comprised of two parts: a material relaxation and a water flux component. Differing contributions by each of the two components at particular ages can explain the observed results.


Asunto(s)
Envejecimiento/fisiología , Ligamentos Articulares/fisiología , Animales , Fenómenos Biomecánicos , Elasticidad , Femenino , Técnicas In Vitro , Articulación de la Rodilla/crecimiento & desarrollo , Articulación de la Rodilla/fisiología , Ligamentos Articulares/crecimiento & desarrollo , Conejos , Valores de Referencia , Resistencia a la Tracción/fisiología , Viscosidad
14.
Ann Acad Med Singap ; 21(2): 280-3, 1992 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-1519903

RESUMEN

The complex nature of the continence mechanism is reflected in the difficulties experienced in the surgical management of patients with faecal incontinence. Apparent anatomical abnormalities may be identified but the functional outcome following surgery may be unsatisfactory. It is therefore important to improve both the selection of patients as well as the surgical procedures themselves. Selection of patients for appropriate treatment should be based on clinical findings as well as anorectal physiology tests. Most patients referred for assessment fall into one of six categories: incontinence with a normal sphincter; minor incontinence due to local anal conditions; direct sphincter injury; neurogenic ("idiopathic") incontinence; rectal prolapse; generalised neurological condition. Minor anal conditions causing incontinence must be carefully identified for appropriate treatment. A large amount of work has been done over the past ten years on the pathophysiology of major incontinence and new surgical procedures have been developed. A common difficulty is deciding whether anterior sphincter attenuation or neurogenic weakness is the dominant lesion causing incontinence; overlapping sphincter repair is indicated for the former and postanal repair for the latter. Anorectal physiology studies can be helpful in differentiating these conditions and are now used routinely in the assessment of patients.


Asunto(s)
Incontinencia Fecal/cirugía , Electromiografía , Estudios de Evaluación como Asunto , Incontinencia Fecal/clasificación , Incontinencia Fecal/diagnóstico , Humanos
15.
Br J Oral Maxillofac Surg ; 33(3): 152-5, 1995 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-7654659

RESUMEN

A case of oral carcinoma associated with extensive leukoplakia and severe xerostomia is presented. The advantage of using a free jejunal patch graft to restore large intra-oral mucosal defects and concurrently eradicate xerostomia is demonstrated. Further, it is recommended that a tracheostomy be used routinely in such cases to avoid postoperative aspiration of the graft secretions. Following healing the use of osseointegrated implants can complete oral rehabilitation without compromising the graft.


Asunto(s)
Carcinoma Verrugoso/cirugía , Yeyuno/trasplante , Leucoplasia Bucal/cirugía , Mucosa Bucal/cirugía , Neoplasias de la Boca/cirugía , Xerostomía/terapia , Anciano , Implantación Dental Endoósea , Implantes Dentales , Femenino , Humanos , Arcada Edéntula/rehabilitación , Arcada Edéntula/cirugía , Síndrome de Sjögren/terapia , Traqueostomía
17.
AJNR Am J Neuroradiol ; 29(10): 1995-7, 2008 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-18653682

RESUMEN

Radiation-induced peripheral nerve tumor, in particular a benign entity such as a neurofibroma, is rare, with only a few cases being reported so far. We demonstrate a case of radiation-induced neurofibromata along the left cervical nerve roots in a man with a background of localized targeted hypofractionated radiation therapy as adjuvant treatment for left cervical nodal metastasis complicating nasopharyngeal carcinoma. The toxicity of high-dose radiation in a hypofractionated regime is also stressed.


Asunto(s)
Imagen por Resonancia Magnética , Neurofibroma/diagnóstico , Neurofibroma/etiología , Neoplasias del Sistema Nervioso Periférico/diagnóstico , Neoplasias del Sistema Nervioso Periférico/etiología , Radioterapia Conformacional/efectos adversos , Raíces Nerviosas Espinales/patología , Adulto , Fraccionamiento de la Dosis de Radiación , Humanos , Masculino
18.
Drug Nutr Interact ; 1(1): 31-44, 1981.
Artículo en Inglés | MEDLINE | ID: mdl-6926814

RESUMEN

Male Holtzman albino rats weighing 60-75 gm were fed purified synthetic diets containing casein (18%), alphacel (4%), wheat starch (44%), sucrose (26%), Jones Foster salt mix (4%), and vitamin mix (4%) for three weeks. The diet for group I contained no fat, whereas corn oil (10%) substituted for 10% sucrose in the diet for group II. All animals were administered 3-methylcholanthrene [20 mg/kg intraperitoneally (ip) in 0.5% methylcellulose solution] for two successive days prior to sacrifice in order to increase the activity of the mixed function oxidase (MFO) responsible for metabolizing benzo(a)pyrene [B(a)P]. After 21 days on diet, livers were perfused with benzo(a)pyrene in blood-free Krebs Henseleit bicarbonate buffer containing 100 mg glucose plus 200 units of heparin per 100 ml. Aliquots of perfusate were removed at five, ten, 20, 30, 40, and 60 minutes for analysis of B(a)P metabolites. Higher concentrations of B(a)P-9, 10-dihydrodiol; B(a)P-4,5-dihydrodiol; B(a)P-7,8-dihydrodiol; and 3-hydroxy B(a)P were recovered from livers of rats fed the diet containing 10% corn oil than from livers of rats fed the fat-free diet. The concentrations of 9-hydroxy B(a)P except the 9,10-dihydrodiol were recovered from bile along with two unidentified metabolites. Following the perfusion period, homogenized and extracted livers from rats fed the diet containing corn oil retained significantly higher concentration of the three dihydrodiols and two phenols than livers from rats fed the fat-free diet.


Asunto(s)
Benzo(a)pireno/metabolismo , Grasas de la Dieta/farmacología , Hígado/metabolismo , Animales , Biotransformación , Hidroxilación , Cinética , Masculino , Perfusión , Ratas
19.
Pharmacology ; 21(1): 64-7, 1980.
Artículo en Inglés | MEDLINE | ID: mdl-7403257

RESUMEN

Isolated livers from rats fed a diet containing corn oil (10% W/W) perfused with a blood-free, modified Krebs-Henseleit solution cleared hexobarbital at a rate significantly faster than livers from rats fed a similar diet devoid of corn oil. The half-lives of hexobarbital in these experiments were 22.4 +/- 1.8 min for livers from rats fed corn oil and 30.0 +/- 1.2 min for those from rats fed the fat-free diet. This represented a metabolic rate of 54 microgram hexobarbital/g liver/min in fat-fed animals and 36 microgram hexobarbital/g liver/min in those fed a rat-free diet.


Asunto(s)
Grasas de la Dieta/farmacología , Hexobarbital/metabolismo , Hígado/metabolismo , Animales , Semivida , Técnicas In Vitro , Cinética , Hígado/efectos de los fármacos , Hígado/enzimología , Masculino , Oxidorreductasas/metabolismo , Ratas
20.
J Biomech Eng ; 117(4): 455-61, 1995 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-8748528

RESUMEN

The relationship between the pattern of surface strain and the site of failure in maturing rabbit ligaments was studied in vitro. Bone-medial collateral ligament (MCL)-bone complexes of 24 female New Zealand White rabbits at 3, 6, 9 and 12 months of age (n = 6 rabbits, 12 MCLs per group) were tested in tension to failure. A video dimension analysis (VDA) system was used to map the surface strain at failure across the width and along the length of the medial side of each MCL during testing. Results showed that the highest strains were consistently located at the femoral insertion decreasing towards the midsubstance, with the highest strain occurring in the anterior portion of the MCL immediately adjacent to the femoral insertion. Strains of the complex at failure increased with rabbit maturation. The strain distribution however, did not change dramatically, even though the locations of MCL failure changed from exclusively tibial avulsion in the three month old rabbits to predominantly midsubstance failures in the 12 month old rabbits. In the six month old rabbits, there was a particular dissociation with all MCLs failing near the tibial insertion while femoral strains were apparently the highest. These results suggest two possibilities beyond that of some unknown artifacts of optical strain measurement. First, since failure sites rarely correlated with areas of maximum surface strain in this study, it seems possible that higher strains could exist deeper in the tissue, particularly at the bone-ligament interface of the tibial insertion in immature animals and somewhere within the midsubstance of the MCL in the adult. Secondly, it is possible that the ligament material may be heterogeneous.


Asunto(s)
Traumatismos de la Rodilla/fisiopatología , Ligamento Colateral Medial de la Rodilla/lesiones , Rango del Movimiento Articular/fisiología , Soporte de Peso/fisiología , Factores de Edad , Animales , Fenómenos Biomecánicos , Femenino , Fémur/lesiones , Fémur/patología , Fémur/fisiopatología , Traumatismos de la Rodilla/patología , Ligamento Colateral Medial de la Rodilla/patología , Ligamento Colateral Medial de la Rodilla/fisiopatología , Conejos , Valores de Referencia , Tibia/lesiones , Tibia/patología , Tibia/fisiopatología
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