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1.
Mol Autism ; 6: 40, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26124950

RESUMEN

BACKGROUND: There is growing research evidence that subclinical autistic traits are elevated in relatives of individuals with autism spectrum disorder (ASD), continuously distributed in the general population and likely to share common etiology with ASD. A number of measures have been developed to assess autistic traits quantitatively in unselected samples. So far, the Quantitative-Checklist for Autism in Toddlers (Q-CHAT) is one of very few measures developed for use with toddlers as young as 18 months, but little is known about its measurement properties and factor structure. METHODS: The present study examined internal consistency, factor structure, test-retest stability, and convergent validity of the Q-CHAT in a sample of toddlers in Singapore whose caregivers completed the Q-CHAT at 18 (n = 368) and 24 months (n = 396). RESULTS: Three factors were derived accounting for 38.1 % of the variance: social/communication traits, non-social/behavioral traits, and a speech/language factor. Internal consistency was suboptimal for the total and speech/language scores, but acceptable for the social/communication and non-social/behavioral factor scores. Scores were generally stable between 18 and 24 months. Convergent validity was found with the Pervasive Developmental Disorders subscale of the Child Behavior Checklist (CBCL) completed by caregivers when their children were 24 months. Q-CHAT total scores in this sample were higher than those reported in other unselected samples from the UK. CONCLUSIONS: The Q-CHAT was found to have a three-factor structure, acceptable internal consistency for its two main factor scores (social/communication and non-social/behavioral), normally distributed scores in an unselected sample, and similar structure and measurement properties as those reported in other published studies. Findings are discussed in relation to existing literature and future directions for the validation of the Q-CHAT.

2.
Cryobiology ; 60(2): 147-58, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19857482

RESUMEN

Coral throughout the world are under threat. To save coral via cryopreservation methods, the Symbiodinium algae that live within many coral cells must also be considered. Coral juvenile must often take up these important cells from their surrounding water and when adult coral bleach, they lose their endosymbiotic algae and will die if they are not regained. The focus of this paper was to understand some of the cryo-physiology of the endosymbiotic algae, Symbiodinium, living within three species of Hawaiian coral, Fungia scutaria, Porites compressa and Pocillopora damicornis in Kaneohe Bay, Hawaii. Although cryopreservation of algae is common, the successful cryopreservation of these important coral endosymbionts is not common, and these species are often maintained in live serial cultures within stock centers worldwide. Freshly-extracted Symbiodinium were exposed to cryobiologically appropriate physiological stresses and their viability assessed with a Pulse Amplitude Fluorometer. Stresses included sensitivity to chilling temperatures, osmotic stress, and toxic effects of various concentrations and types of cryoprotectants (i.e., dimethyl sulfoxide, propylene glycol, glycerol and methanol). To determine the water and cryoprotectant permeabilities of Symbiodinium, uptake of radio-labeled glycerol and heavy water (D(2)O) were measured. The three different Symbiodinium subtypes studied demonstrated remarkable similarities in their morphology, sensitivity to cryoprotectants and permeability characteristics; however, they differed greatly in their sensitivity to hypo- and hyposmotic challenges and sensitivity to chilling, suggesting that standard slow freezing cryopreservation may not work well for all Symbiodinium. An appendix describes our H(2)O:D(2)O water exchange experiments and compares the diffusionally determined permeability with the two parameter model osmotic permeability.


Asunto(s)
Antozoos/microbiología , Criopreservación , Dinoflagelados/fisiología , Animales , Permeabilidad de la Membrana Celular , Conservación de los Recursos Naturales , Criopreservación/métodos , Crioprotectores/farmacocinética , Crioprotectores/toxicidad , Óxido de Deuterio , Dinoflagelados/clasificación , Dinoflagelados/efectos de los fármacos , Glicerol/farmacocinética , Glicerol/toxicidad , Presión Osmótica , Especificidad de la Especie , Simbiosis
3.
J Mater Sci Mater Med ; 19(5): 2113-9, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-17136608

RESUMEN

Sodium alginate is a useful polymer for the encapsulation and immobilization of a variety of cells in tissue engineering because it is biocompatible, biodegradable and easy to process into injectable microbeads. Despite these properties, little is known of the efficacy of calcium cross-linked alginate gel beads as a biodegradable scaffold for osteogenic cell proliferation and differentiation. In this study, we investigated the ability of rabbit derived bone marrow cells (BMCs) to proliferate and differentiate in alginate microbeads and compared them with BMCs cultured in poly-L-lysine (PLL) coated microbeads and on conventional 2D plastic surfaces. Results show that levels of proliferation and differentiation in microbeads and on tissue culture plastics were comparable. Cell proliferation in microbeads however diminished after fortification with a coating layer of PLL. Maximum cell numbers observed were, 3.32 x 10(5) +/- 1.72 x 103; 3.11 x 10(5) +/- 1.52 x 10(3) and 3.28 x 10(5) +/- 1.21 x 10(3 ) for the uncoated, PLL coated and plastic surface groups respectively. Alkaline phosphatase and protein expressions reflected the stage of cell differentiation. We conclude that calcium cross-linked alginate microbeads can act as a scaffold for BMC proliferation and osteogenic differentiation and has potential for use as 3D degradable scaffold.


Asunto(s)
Alginatos/química , Materiales Biocompatibles/química , Células de la Médula Ósea/citología , Fosfatasa Alcalina/metabolismo , Animales , Calcio/química , Diferenciación Celular , Proliferación Celular , Supervivencia Celular , Medio de Cultivo Libre de Suero/química , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Osteogénesis , Plásticos , Polilisina/química , Conejos , Ingeniería de Tejidos/métodos
4.
Clin Orthop Relat Res ; 460: 124-9, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-17438475

RESUMEN

We describe a direct internal kyphectomy through a modified costotransversectomy, an extrapleural approach to the kyphus that does not jeopardize already compromised pulmonary function. A curved longitudinal incision is made 6 to 8 cm lateral to the midline. The posterior 5 cm of the two to three crowded ribs at the apex are resected. The segmental intercostal nerves are preserved as a guide into the spinal canal. Two to three pedicles at the apex are resected. The pleura are elevated with blunt dissection leading to the internal kyphus. Removal of the posterior half of the collapsed vertebrae is performed with a high-speed burr; the posterior walls are removed last to avoid forward migration of the dural sac as the decompression progresses. Cortical strut grafting is then performed as far anteriorly as the exposure permits. We treated five patients with paraparesis of healed disease with this approach. Preoperatively the mean kyphosis was 114 degrees. Neurological improvement was obtained in two patients. At a mean followup of 5 years, solid anterior fusion was achieved in four patients. One patient died 5 months after surgery because of chest infection.


Asunto(s)
Cifosis/cirugía , Fusión Vertebral/métodos , Tuberculosis de la Columna Vertebral/cirugía , Adulto , Descompresión Quirúrgica , Femenino , Humanos , Cifosis/diagnóstico por imagen , Cifosis/etiología , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Resultado del Tratamiento , Tuberculosis de la Columna Vertebral/complicaciones , Tuberculosis de la Columna Vertebral/diagnóstico por imagen
5.
J Med Genet ; 44(4): 285-8, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17220213

RESUMEN

BACKGROUND: Lumbar disc disease (LDD) is one of the leading causes of disability in the working-age population. A functional single-nucleotide polymorphism (SNP), +1184T-->C, in exon 8 of the cartilage intermediate layer protein gene (CILP) was recently identified as a risk factor for LDD in the Japanese population (odds ratio (OR) 1.61, 95% CI 1.31 to 1.98), with implications for impaired transforming growth factorbeta1 signalling. AIM: To validate this finding in two different ethnic cohorts with LDD. METHODS: This SNP and flanking SNPs were analysed in 243 Finnish patients with symptoms of LDD and 259 controls, and in 348 Chinese subjects with MRI-defined LDD and 343 controls. RESULTS AND CONCLUSION: The results showed no evidence of association in the Finnish (OR = 1.35, 95% CI 0.97 to 1.87; p = 0.14) or the Chinese (OR = 1.05, 95% CI 0.77 to 1.43; p = 0.71) samples, suggesting that cartilage intermediate layer protein gene is not a major risk factor for symptoms of LDD in Caucasians or in the general population that included individuals with or without symptoms.


Asunto(s)
Proteínas de la Matriz Extracelular/genética , Desplazamiento del Disco Intervertebral/genética , Vértebras Lumbares , Polimorfismo de Nucleótido Simple , Pirofosfatasas/genética , Ciática/genética , Estudios de Cohortes , Exones/genética , Proteínas de la Matriz Extracelular/fisiología , Femenino , Finlandia/epidemiología , Predisposición Genética a la Enfermedad , Genotipo , Hong Kong/epidemiología , Humanos , Desplazamiento del Disco Intervertebral/complicaciones , Desplazamiento del Disco Intervertebral/epidemiología , Masculino , Pirofosfatasas/fisiología , Ciática/epidemiología , Ciática/etiología , Índice de Severidad de la Enfermedad , Transducción de Señal/fisiología , Factor de Crecimiento Transformador beta1/fisiología
6.
J Hand Surg Eur Vol ; 32(1): 38-44, 2007 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17126969

RESUMEN

This paper reports the results of treatment by proximal relocation of 46 painful end-neuromas or scarred nerves in 33 patients from the pre-defined Zone II of the hand. The relocated nerves included four palmar cutaneous branches of the median nerve, 17 dorsal branches of the ulnar nerves and 25 digital nerves. If no pain at the original site and no pain or only mild pain at the relocation site are considered an adequate treatment of these difficult problems, these relocation procedures achieve complete control of spontaneous baseline pain, complete control of spontaneous spikes of pain, 93% control of direct pressure pain, complete control of movement pain (excluding the extremes of movement of the wrist into extension, supination and, less frequently, pronation) and 96% control of hypersensitivity of the overlying skin.


Asunto(s)
Cicatriz/cirugía , Dedos/inervación , Mano/inervación , Mano/cirugía , Neuropatía Mediana/cirugía , Músculo Esquelético/cirugía , Neuroma/cirugía , Neoplasias del Sistema Nervioso Periférico/cirugía , Neuropatías Cubitales/cirugía , Adolescente , Adulto , Cicatriz/fisiopatología , Potenciales Evocados Somatosensoriales/fisiología , Femenino , Estudios de Seguimiento , Humanos , Masculino , Neuropatía Mediana/fisiopatología , Persona de Mediana Edad , Neuroma/fisiopatología , Nociceptores/fisiopatología , Dimensión del Dolor , Umbral del Dolor/fisiología , Neoplasias del Sistema Nervioso Periférico/fisiopatología , Proyectos Piloto , Estudios Prospectivos , Transmisión Sináptica/fisiología , Neuropatías Cubitales/fisiopatología
7.
Biochem Biophys Res Commun ; 347(1): 185-91, 2006 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-16815293

RESUMEN

This study aims to investigate the survival and osteogenic behavior of murine-derived adipose-tissue stromal cells (ATSCs) encapsulated in alginate microcapsules thereby instigating further studies in this cell delivery strategy for in vivo osteogenesis. Cell viability was quantified using a tetrazolium-based assay and osteogenic differentiation was evaluated by both alkaline-phosphatase (ALP) histochemistry and osteocalcin mRNA analysis. Following microencapsulation, cell numbers increased from 3.9 x 10(3) on day 1 to 7.8 x 10(3) on day 7 and maintained excellent viability in the course of 21-day culture. ALP was 6.9, 5.5, and 3.2 times higher than monolayer cultures on days 7, 14, and 21, respectively. In addition, osteocalcin mRNA was detectable in encapsulated cultures earlier (day 14) than monolayer cultures. We conclude that alginate microcapsules can act as three-dimensional matrix for ATSC proliferation and has potential for use as injectable, biodegradable scaffold in bone tissue engineering.


Asunto(s)
Adipocitos/citología , Adipocitos/trasplante , Alginatos/química , Sustitutos de Huesos/administración & dosificación , Sustitutos de Huesos/química , Osteoblastos/citología , Ingeniería de Tejidos/métodos , Animales , Materiales Biocompatibles/química , Trasplante Óseo/métodos , Técnicas de Cultivo de Célula/métodos , Diferenciación Celular , Trasplante de Células/métodos , Células Cultivadas , Materiales Biocompatibles Revestidos/química , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Inyecciones/métodos , Ratones , Ratones Transgénicos , Células del Estroma/citología , Células del Estroma/trasplante
8.
Spine (Phila Pa 1976) ; 31(14): 1532-8, 2006 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-16778684

RESUMEN

STUDY DESIGN: Establishment of a novel in vivo animal model of cervical spondylosis. OBJECTIVE: To investigate apoptotic, degenerative, and inflammatory changes occurring in the cervical intervertebral discs of rats. SUMMARY OF BACKGROUND DATA: Cervical degeneration occurs as the result of imbalance of both static and dynamic spinal stabilizers. The disc degeneration that occurs is characterized by increased local inflammation and increased apoptosis of intervertebral disc cells. METHODS: By excising the paraspinal musculature and posterior cervical spinal ligaments of rats, both static and dynamic cervical stabilizers were disrupted. The resultant biomechanical imbalance resulted in biochemical and histologic changes, which were characterized by light microscopy, electron microscopy, immunostaining, enzyme-linked immunosorbent assay, polymerase chain reaction, and in situ hybridization. RESULTS: Histologic analysis showed characteristic degenerative changes of the intervertebral discs and vertebral endplates following surgery. Ultrastructural examination revealed apoptotic changes, which were verified by immunostaining. Instability also resulted in significant up-regulation of inflammatory factors, as shown by enzyme-linked immunosorbent assay, polymerase chain reaction, and in situ hybridization. CONCLUSIONS: By creating static and dynamic posterior instability of the cervical spine, this novel model of cervical spondylosis results in rapid intervertebral disc degeneration characterized by increased apoptosis and local inflammation, such as that seen clinically.


Asunto(s)
Vértebras Cervicales , Modelos Animales de Enfermedad , Disco Intervertebral , Ratas , Osteofitosis Vertebral/etiología , Animales , Apoptosis , Vértebras Cervicales/metabolismo , Vértebras Cervicales/patología , Vértebras Cervicales/fisiopatología , Colagenasas/metabolismo , Citocinas/metabolismo , Ensayo de Inmunoadsorción Enzimática , Femenino , Inmunohistoquímica , Hibridación in Situ , Etiquetado Corte-Fin in Situ , Mediadores de Inflamación/metabolismo , Disco Intervertebral/metabolismo , Disco Intervertebral/patología , Disco Intervertebral/fisiopatología , Masculino , Microscopía Electrónica , Ratas Sprague-Dawley , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Osteofitosis Vertebral/metabolismo , Osteofitosis Vertebral/patología , Osteofitosis Vertebral/fisiopatología , Inhibidores Tisulares de Metaloproteinasas/metabolismo
9.
Cryobiology ; 52(3): 454-8, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16626677

RESUMEN

Coral species throughout the world are facing severe environmental pressures. Because of this, we began cryobiological studies on the sperm of the mushroom coral, Fungia scutaria. We determined that F. scutaria sperm had a mean length of 56 microm and head diameter of 2.5 microm, and a mean spontaneous ice nucleation temperature of -37.2 +/- 1.7 degrees C. When the sperm were exposed to the cryoprotectant glycerol for 5 or 20 min (at 10% v/v), no fertilized larvae were produced. However, when sperm were exposed for 20 min to propylene glycol (10% v/v), fertilizations were produced at the same rate as untreated control eggs and sperm (P > 0.05), but slightly less for dimethyl sulfoxide (10% v/v) (P < 0.05). Regardless, dimethyl sulfoxide caused less osmotic damage to the sperm membrane than did propylene glycol. Therefore, we used the dimethyl sulfoxide (10% v/v) to develop cryopreservation protocols that yielded good post-thaw morphology and motility (>95%) for coral sperm.


Asunto(s)
Antozoos , Criopreservación , Espermatozoides , Animales , Crioprotectores/farmacología , Dimetilsulfóxido/farmacología , Fertilización/efectos de los fármacos , Glicerol/farmacología , Masculino , Propilenglicol/farmacología , Espermatozoides/efectos de los fármacos , Espermatozoides/fisiología
10.
Cryobiology ; 52(1): 33-47, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16337183

RESUMEN

Coral species throughout the world's oceans are facing severe environmental pressures. We are interested in conserving coral larvae by means of cryopreservation, but little is known about their cellular physiology or cryobiology. These experiments examined cryoprotectant toxicity, dry weight, water and cryoprotectant permeability using cold and radiolabeled glycerol, spontaneous ice nucleation temperatures, chilling sensitivity, and settlement of coral larvae. Our two test species of coral larvae, Pocillopora damicornis (lace coral), and Fungia scutaria (mushroom coral) demonstrated a wide tolerance to cryoprotectants. Computer-aided morphometry determined that F. scutaria larvae were smaller than P. damicornis larvae. The average dry weight for P. damicornis was 24.5%, while that for F. scutaria was 17%, yielding osmotically inactive volumes (V(b)) of 0.22 and 0.15, respectively. The larvae from both species demonstrated radiolabeled glycerol uptake over time, suggesting they were permeable to the glycerol. Parameter fitting of the F. scutaria larvae data yielded a water permeability 2 microm/min/atm and a cryoprotectant permeability = 2.3 x 10(-4) cm/min while modeling indicated that glycerol reached 90% of final concentration in the larvae within 25 min. The spontaneous ice nucleation temperature for F. scutaria larvae in filtered seawater was -37.8+/-1.4 degrees C. However, when F. scutaria larvae were chilled from room temperature to -11 degrees C at various rates, they exhibited 100% mortality. When instantly cooled from room temperature to test temperatures, they showed damage below 10 degrees C. These data suggest that they are sensitive to both the rate of chilling and the absolute temperature, and indicate that vitrification may be the only means to successfully cryopreserve these organisms. Without prior cryopreservation, both species of coral settled under laboratory conditions.


Asunto(s)
Antozoos/fisiología , Larva/crecimiento & desarrollo , Reproducción/fisiología , Animales , Antozoos/crecimiento & desarrollo , Permeabilidad de la Membrana Celular/efectos de los fármacos , Criopreservación/métodos , Crioprotectores/metabolismo , Crioprotectores/farmacología , Congelación , Glicerol/metabolismo , Glicerol/farmacología , Hielo , Larva/fisiología , Sensibilidad y Especificidad , Especificidad de la Especie , Temperatura
11.
Gait Posture ; 22(3): 189-97, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16214658

RESUMEN

This study evaluated the biomechanical and electromyographic effects of conventional ankle foot orthoses (AFOs) and dynamic ankle foot orthoses (DAFOs) on gait in patients with spastic cerebral palsy (CP). Thirteen patients with dynamic equinus underwent motion analysis with electromyography. Both AFOs and DAFOs provided longer stride length, permitted pre-positioning for initial contact, and successfully controlled the excessive plantarflexion during the swing phase. Median frequency (MF) of EMG signal indicated that extremely high firing was found in the patient's lower limbs compared to controls that resulted in tiredness. The DAFOs allowed a significantly larger total ankle range of motion than the AFOs. However, AFOs significantly reduced the MF while DAFOs did not. The reduced MF seen when wearing AFOs suggested an improvement of walking endurance. The DAFO had the advantage of less restriction on ankle movement, which avoids muscular atrophy and improves orthotic compliance.


Asunto(s)
Articulación del Tobillo , Parálisis Cerebral/fisiopatología , Marcha , Aparatos Ortopédicos , Articulación del Tobillo/fisiopatología , Fenómenos Biomecánicos , Parálisis Cerebral/rehabilitación , Niño , Preescolar , Electromiografía , Femenino , Pie , Articulación de la Cadera/fisiopatología , Humanos , Articulación de la Rodilla/fisiopatología , Masculino , Espasticidad Muscular , Rango del Movimiento Articular , Caminata
12.
J Fish Dis ; 28(7): 399-410, 2005 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16083445

RESUMEN

Delivery of phosphorodiamidate morpholino oligomers (PMO) into fish cells in vitro and tissues in vivo was examined. Uptake was evaluated by fluorescence microscopy and flow cytometry after treating cultured cells or live rainbow trout with 3' fluorescein-tagged PMO. Arginine-rich peptide conjugated to the 5' end of the PMO markedly enhanced cellular uptake in culture by 8- to 20-fold compared with non-peptide-conjugated PMO as determined by flow cytometry. Enhanced uptake of PMO conjugated to peptide was also observed in tissues of fish treated by immersion. The efficacy of PMO as inhibitors of infectious haematopoietic necrosis virus (IHNV) replication was determined in vitro. Peptide-conjugated PMOs targeting sequences within the IHNV genomic RNA (negative polarity) or antigenomic RNA (positive polarity) significantly inhibited replication in a dose-dependent and sequence-specific manner. A PMO complementary to sequence near the 5' end of IHNV genomic RNA was the most effective, diminishing titre by 97%, as measured by plaque assay and Western blot. These data demonstrate that replication of a negative-stranded non-segmented RNA virus can be inhibited by antisense compounds that target positive polarity viral RNA, or by a compound that targets negative polarity viral RNA.


Asunto(s)
Antivirales/farmacología , Virus de la Necrosis Hematopoyética Infecciosa/efectos de los fármacos , Virus de la Necrosis Hematopoyética Infecciosa/genética , Morfolinas/farmacología , Oncorhynchus mykiss/metabolismo , ARN Viral/metabolismo , Animales , Antivirales/farmacocinética , Emparejamiento Base , Secuencia de Bases , Western Blotting , Línea Celular , Relación Dosis-Respuesta a Droga , Citometría de Flujo , Microscopía Fluorescente , Morfolinas/química , Morfolinas/farmacocinética , Morfolinos , Péptidos/metabolismo
13.
J Biomed Mater Res A ; 70(3): 428-35, 2004 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-15293316

RESUMEN

The purpose of this study was to investigate the mineralization leading to osseointegration of strontium-containing hydroxyapatite (Sr-HA) bioactive bone cement injected into cancellous bone in vivo. Sr-HA cement was injected into the ilium of rabbits for 1, 3, and 6 months. The bone mineralization area was found to be largest at 3 months, then at 1 month, and smallest at 6 months (p < 0.01) measured with tetracycline labeling. Osseointegration of Sr-HA cement was achieved at 3 months as observed by scanning electron microscopy. A high calcium and phosphorus area was observed at the interface of bone-Sr-HA cement determined by energy-dispersive X-ray analysis. Transmission electron microscopy gave evidence of the mechanism of bone formation. Dissolution of Sr-HA into debris by the bone remodeling process was thought to increase the concentration of calcium and phosphorus at the interface of bone-Sr-HA cement and stimulate bone formation. Crystalline Sr-HA formed an amorphous layer and dissolved into the surrounding solution, then apatite crystallites were precipitated and formed new bone at 3 months. This young bone then becomes mature bone, which bonds tightly to the Sr-HA cement with collagen fibers inserted perpendicularly after 6 months.


Asunto(s)
Cementos para Huesos/química , Calcificación Fisiológica/fisiología , Hidroxiapatitas/química , Estroncio/química , Animales , Materiales Biocompatibles/química , Materiales Biocompatibles/metabolismo , Cementos para Huesos/metabolismo , Hidroxiapatitas/metabolismo , Ilion/fisiología , Ilion/ultraestructura , Ensayo de Materiales , Oseointegración/fisiología , Conejos , Estroncio/metabolismo
14.
Spine (Phila Pa 1976) ; 29(11): 1196-201; discussion 1202, 2004 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-15167657

RESUMEN

STUDY DESIGN: Fifty-five human thoracolumbar vertebrae were randomly fatigue loaded and analyzed. OBJECTIVES: The purpose of this study was to explore the relationship between fatigue loading, trabecular microfracture, and energy absorption to fracture in human cadaveric thoracolumbar vertebrae. BACKGROUND: Although trabecular microfractures are found in vivo and have been produced by fatigue loading in vitro, the effect of the level of physiologic fatigue loading on microfracture and energy absorption has not been investigated. METHODS: Fifty-five human thoracolumbar vertebrae (T11-L4) were randomly divided into 5 groups: 1) control (no loading, n = 6); 2) axial compression to yield (n = 7); and 3-5) 20,000 cycles of fatigue loading at 2 Hz (each n = 14). The level of fatigue loading was determined as a proportion of the yield load of Group 2 as follows: 10% (Group 3), 20% (Group 4), and 30% (Group 5). Half of the specimens in groups 3 to 5 were used for radiographic and histomorphometric analysis to determine microfracture density and distribution, whereas the other half were tested to determine the energy absorption to yield failure. RESULTS: No radiographic evidence of gross fracture was found in any of the groups following fatigue loading. A mean 7.5% increase in stiffness was found in specimens subject to cyclic loading at 10% of yield stress (Group 3). Fatigue at 20% (Group 4) and 30% of yield stress (Group 5) caused significantly higher (P < 0.05) increases in mean stiffness of 23.6% and 24.2%, respectively. Microfracture density increased from 0.46/mm in Group 3 to 0.66/mm in Group 4 and 0.94/mm in Group 5 (P < 0.05). The energy absorbed to failure decreased from 21.9 J in Group 3 to 18.1 J and 19.6 J in Groups 4 and 5, respectively (P < 0.05). CONCLUSIONS: Fatigue loading at physiologic levels produced microfractures that are not detectable by radiography. Increased fatigue load results in an increase in microfracture density and decrease energy absorbed to fracture, indicating a reduced resistance to further fatigue loading.


Asunto(s)
Fracturas por Estrés/diagnóstico por imagen , Fracturas por Estrés/patología , Fracturas de la Columna Vertebral/diagnóstico por imagen , Fracturas de la Columna Vertebral/patología , Absorciometría de Fotón , Adulto , Fenómenos Biomecánicos , Fracturas por Estrés/etiología , Humanos , Masculino , Fracturas de la Columna Vertebral/etiología , Soporte de Peso
15.
Biomaterials ; 25(18): 4243-54, 2004 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15046914

RESUMEN

The formation and strengthening mechanisms of bone bonding of crystalline hydroxyapatite (HA) has been investigated using high-resolution transmission electron microscope (HRTEM) and energy-dispersive X-ray (EDX) analysis. A series of results were obtained: (i) a layer of amorphous HA, which has almost the same chemistry as the implanted HA, was formed on the surface of crystalline HA particles prior to dissolution; (ii) at 3 months a bone-like tissue formed a bonding zone between mature bone and the HA implant, composed of nanocrystalline and amorphous apatite; and (iii) at 6 months, mature bone was in direct contact with HA particles, and collagen fibres were perpendicularly inserted into the surface layer of implanted HA crystals. Findings (i) and (ii) indicated the following dissolution-precipitation process. (i) The crystalline HA transforms into amorphous HA; (ii) the amorphous HA dissolves into the surrounding solution, resulting in over-saturation; and (iii) the nanocrystallites are precipitated from the over-saturated solution in the presence of collagen fibres. A preliminary analysis indicated several conclusions: (i) the transition from crystalline to amorphous HA might be the controlling step in the bone bonding of crystalline HA; (ii) biological interdigitation (or incorporation) of collagen fibres with HA and chemical bonding of a apatite layer were both necessary to strengthen and toughen a bone bond, not only for the bonding between bone and HA at 6 months, but also for the bonding zone at 3 months, which would otherwise be very fragile due to the inherited brittleness of polycrystalline ceramics; and (iii) perpendicular interdigitation is an effective way for collagen fibres to impart their unique combination of flexibility and strength to the interface which they are keying.


Asunto(s)
Cementos para Huesos/química , Sustitutos de Huesos/administración & dosificación , Sustitutos de Huesos/química , Durapatita/administración & dosificación , Durapatita/química , Ilion/efectos de los fármacos , Ilion/patología , Adhesividad , Animales , Remodelación Ósea/efectos de los fármacos , Remodelación Ósea/fisiología , Cristalización , Ilion/cirugía , Ensayo de Materiales , Conejos , Cicatrización de Heridas/efectos de los fármacos , Heridas Penetrantes/tratamiento farmacológico , Heridas Penetrantes/patología
16.
J Biomed Mater Res B Appl Biomater ; 69(1): 79-86, 2004 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-15015214

RESUMEN

A novel injectable bioactive bone-bonding cement (SrHAC) composed of strontium-containing hydroxyapatite (Sr-HA) as the inorganic filler and bisphenol A diglycidylether dimethacrylate (Bis-GMA) as the organic matrix for vertebroplasty was developed previously. In this study, the Sr-HA powders were surface treated with methyl methacrylate (MMA) to improve the interface integration of the two phases. After surface treatment, the compression strength and Young's modulus, which were tested after immersion in distilled water at 37 degrees C for 24 h according to ISO 5833, were increased by 68.65 % (p <.001) and 31.02% (p <.001), respectively. The bending strength and bending stiffness of the bioactive bone cement were significantly improved by 54.44% (p <.001) and 83.90% (p <.001). In addition, the handling property of the cement was also enhanced. In vitro biomechanical testing showed that the stiffness of the fractured spine recovered to 82.5% (p <.01) of the intact condition after cementation with surface-treated SrHAC. The failure load of the spine cemented with original and MMA-treated SrHAC improved by 14.25% (p <.05) and 46.91% (p <.05) in comparison with the fractured spines. Results from this study revealed that the MMA-treated SrHAC has a better mechanical effect for orthopedic applications.


Asunto(s)
Materiales Biocompatibles/química , Cementos para Huesos/química , Hidroxiapatitas/química , Metilmetacrilato/química , Columna Vertebral/cirugía , Estroncio/química , Animales , Materiales Biocompatibles/administración & dosificación , Fenómenos Biomecánicos , Fuerza Compresiva , Fracturas Óseas/cirugía , Hidroxiapatitas/administración & dosificación , Inyecciones , Microscopía Electrónica de Rastreo , Estructura Molecular , Equipo Ortopédico , Radiografía , Análisis Espectral , Columna Vertebral/diagnóstico por imagen , Estroncio/administración & dosificación , Porcinos , Temperatura
17.
J Biomed Mater Res A ; 68(3): 513-21, 2004 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-14762931

RESUMEN

The purpose of this study was to investigate the in vivo bone response to the strontium-containing hydroxyapatite (Sr-HA) bioactive bone cement injected into the cancellous bone. Sr-HA cement was injected into the iliac crest of rabbits for 1, 3, and 6 months. Active bone formation and remodeling were observed after 1 month. Newly formed bone was observed to grow onto the bone cement after 3 months. Thick osteoid layer with osteoblasts formed along the bone and guided over the bone cement surface reflected the stimulating effect of Sr-HA. From scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis, high calcium and phosphorus levels were detected at the interface with a thick layer of 70 microm in width, and fusion of Sr-HA with the bone was observed. Blood vessels were found developing in remodeling sites. The affinity of bone on Sr-HA cement was increased from 73.55 +/- 3.50% after 3 months up to 85.15 +/- 2.74% after 6 months (p < 0.01). In contrast to Sr-HA cement, poly(methyl methacrylate) (PMMA) bone cement was neither osteoconductive nor bioresorbable. Results show that the Sr-HA cement is biocompatible and osteoconductive, which is suitable for use in treating osteoporotic vertebral fractures.


Asunto(s)
Cementos para Huesos/química , Cementos para Huesos/farmacología , Remodelación Ósea/efectos de los fármacos , Durapatita , Animales , Biodegradación Ambiental , Cementos para Huesos/normas , Ilion , Ensayo de Materiales , Neovascularización Fisiológica/efectos de los fármacos , Osteoblastos/citología , Osteoblastos/efectos de los fármacos , Polimetil Metacrilato , Conejos , Estroncio
18.
Spine (Phila Pa 1976) ; 29(2): 123-8, 2004 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-14722402

RESUMEN

STUDY DESIGN: Experimental animal study. OBJECTIVES: To investigate whether the increase in spinal flexibility after chymopapain injection is dose dependent and determine the "optimal" dosage of chymopapain to increase spinal flexibility in a rabbit model. SUMMARY OF BACKGROUND DATA: Spinal instability after chymopapain injection may result in severe back pain. However, this undesired mechanical effect in treating disc herniation may provide a safe minimally invasive approach for anterior spinal release in scoliosis correction. METHODS: A total of 138 lumbar intervertebral discs from 46 New Zealand white rabbits were randomly injected with chymopapain at 6.25, 12.5, 25, 50, 75, and 100 picokatals (pKats)/0.05 mL/disc. The rabbits were killed 1 week after the injection, and the lateral bending stiffness of the spinal segments without posterior elements was determined. RESULTS: The lateral bending spinal stiffness showed no significant change after injection of 6.25 and 12.5 pKats/0.05 mL/disc but reduced significantly following chymopapain injection of 25, 50, 75, and 100 pKats (all P < 0.05 by post hoc least significant difference tests). While the lateral bending stiffness was lowest at the 100-pKats dose, there were no significant differences between the four higher dosages. CONCLUSION: The reduction in the lateral bending spinal stiffness after chymopapain injection is dose dependent, and an optimal dosage for spinal release existed; doses greater than the optimal dosage did not result in further significant decrease in lateral bending spinal stiffness.


Asunto(s)
Quimopapaína/farmacología , Quimiólisis del Disco Intervertebral/métodos , Disco Intervertebral/efectos de los fármacos , Disco Intervertebral/fisiología , Columna Vertebral/efectos de los fármacos , Columna Vertebral/fisiología , Animales , Fenómenos Biomecánicos , Quimopapaína/administración & dosificación , Relación Dosis-Respuesta a Droga , Técnicas In Vitro , Inyecciones , Disco Intervertebral/citología , Región Lumbosacra , Procedimientos Quirúrgicos Mínimamente Invasivos/métodos , Modelos Animales , Docilidad/efectos de los fármacos , Conejos , Rango del Movimiento Articular/efectos de los fármacos , Escoliosis/tratamiento farmacológico
19.
Conf Proc IEEE Eng Med Biol Soc ; 2004: 4944-7, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-17271422

RESUMEN

Functional electrical stimulation (FES) has been employed in paraplegic rehabilitation to resume their walking ability. However, there is less quantitative assessment method of FES walking efficiency and rehabilitation progress. This paper presents a new dynamical measurement of upper limb support force during paraplegic walking, which can be used to calculate the 3-D handle reaction vector (HRV). HRV may provide an assessment of FES-assisted efficiency. With a series of tests, the measurement accuracy, nonlinearity, and crosstalk of the designed system are testified. The force measurement error is found below 1.01%, while nonlinearity and crosstalk are less than 2.90%, and 3.19%, respectively. This means that the implemented walker system is reliable for the measurement of HRV during FES-assisted walking. A clinical trial is performed with a paraplegic subject. With the monitoring of FES-assisted walking, the downward component of HRV is found to decrease, implying the decreasing force generated from lower limb. The decrease slope in downward load curve can indirectly indicate the FES efficiency change during walking. The experiment and clinical trial results show that a 3-D dynamical measurement system is successfully accomplished to indirectly assess FES efficiency of lower limbs using quantitated forces applied by the upper limbs of paraplegic patients.

20.
Int Orthop ; 28(1): 36-9, 2004 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-14534831

RESUMEN

From February 2001 to May 2001, 792 latex gloves used in 100 operations from three orthopaedic sub-specialties (paediatrics, hand and spine) were tested for puncture by a water infusion test. Sixty-nine gloves from 45 operations were punctured, giving an overall glove perforation rate of 8.7% (69/792) and an operative perforation rate of 45% (45/100). The hand operations had the lowest operative perforation rate (19.4%) while the spine operations had the highest (63.6%). The glove perforation rate increased in bony procedures (60% versus 22.5%), in procedures with major instrumentation (66% versus 18%) and in more lengthy procedures. The thumbs and the left index finger had more punctures than other parts. In addition, the glove perforation rate for single gloving was 9.6% (53/552) while that for the inner glove of double gloving was 0.8% (1/120). Based on these findings, we would like to recommend double gloving and regular glove changing in these high-risk surgeries.


Asunto(s)
Falla de Equipo , Guantes Quirúrgicos , Procedimientos Ortopédicos/efectos adversos , Humanos
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