Percutaneous vertebroplasty: a new animal model.

Background Context Percutaneous vertebroplasty (PVP) is a minimally invasive surgical procedure and is frequently performed in humans who need surgical treatment of vertebral fractures. PVP involves cement injection into the vertebral body, thereby providing rapid and significant pain relief. Purpose The testing of novel biomaterials depends on suitable animal models. The aim of this study was to develop a reproducible and safe model of PVP in sheep. Study Design This study used ex vivo and in vivo large animal model study (Merino sheep). Methods Ex vivo vertebroplasty was performed through a bilateral modified parapedicular access in 24 ovine lumbar hemivertebrae, divided into four groups (n=6). Cerament (Bone Support, Lund, Sweden) was the control material. In the experimental group, a novel composite was tested—Spine-Ghost—which consisted of an alpha-calcium sulfate matrix enriched with micrometric particles of mesoporous bioactive glass. All vertebrae were assessed by micro-computed tomography (micro-CT) and underwent mechanical testing. For the in vivo study, 16 sheep were randomly allocated into control and experimental groups (n=8), and underwent PVP using the same bone cements. All vertebrae were assessed postmortem by micro-CT, histology, and reverse transcription-polymerase chain reaction (rt-PCR). This work has been supported by the European Commission under the 7th Framework Programme for collaborative projects (600,000–650,000 USD). Results In the ex vivo model, the average defect volume was 1,275.46±219.29 mm3. Adequate defect filling with cement was observed. No mechanical failure was observed under loads which were higher than physiological. In the in vivo study, cardiorespiratory distress was observed in two animals, and one sheep presented mild neurologic deficits in the hind limbs before recovering. Conclusions The model of PVP is considered suitable for preclinical in vivo studies, mimicking clinical application. All sheep recovered and completed a 6-month implantation period. There was no evidence of cement leakage into the vertebral foramen in the postmortem examination.

Isolation and characterization of plastid terminal oxidase gene from carrot and its relation to carotenoid accumulation

Carrot (Daucus carota L.) is a biennial plant that accumulates considerable amounts of carotenoid pigments in the storage root. To better understand the molecular mechanisms for carotenoid accumulation in developing storage roots, plastid terminal oxidase (PTOX) cDNA was isolated and selected for reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Present in photosynthetic species, PTOX is a plastid-located, nucleus encoded plastoquinone (PQ)-O2 oxidoreductase (plastioquinol oxidase). The enzyme is known to play a role as a cofactor for phytoene desaturase, and consequently plays a key role in the carotenoid biosynthesis pathway. A single PTOX gene was identified (DcPTOX) in carrot. DcPTOX encodes a putative protein with 366 amino acids that contains the typical structural features of PTOXs from higher plants. The expression of DcPTOX was analysed during the development of white, yellow, orange, red, and purple carrot roots, along with five genes known to be involved in the carotenoid biosynthesis pathway, PSY2, PDS, ZDS1, LCYB1, and LCYE. Expression analysis revealed the presence of DcPTOX transcripts in all cultivars, and an increase of transcripts during the time course of the experiment, with differential expression among cultivars in early stages of root growth. Our results demonstrated that DcPTOX showed a similar profile to that of other carotenoid biosynthetic genes with high correlation to all of them. The preponderant role of PSY in the biosynthesis of carotenoid pigments was also confirmed.