Reversal of suppressed metabolism in prolonged cold preserved cartilage

Chondrocytes in cold preserved cartilage are metabolically suppressed. The goal of this study was to address this metabolic suppression and seek ways to reverse it. Specifically, we examined the roles of rewarming protocols and nitric oxide (NO) in this metabolic suppression. Bovine and canine full-thickness articular cartilage explants were cultured under various temperature conditions, and NO production, proteoglycan (PG) synthesis, and cell viability were measured. Nitric oxide was shown to be negatively correlated with PG synthesis following abrupt rewarming of cold preserved osteochondral allografts. Gradual rewarming of the allograft tissue decreased NO production with higher PG synthesis. Inhibition of nitric oxide synthases (NOS) led to a decrease in NO production and a concomitant increase in PG synthesis. We were able to partially reverse metabolic suppression of cold preserved osteochondral allograft material with gradual rewarming and decrease NO production with NOS inhibition. Chondrocytes in cold preserved allograft material may be metabolically suppressed predisposing the graft to failure in vivo. Minimizing this loss of metabolic function by gradual graft rewarming and decreasing NO production by NOS inhibition at the time of graft implantation may have implications on graft survival in vivo.

Jagged1 peptide appearing in mandibular condylar cartilage development

We investigated the expression pattern of Jagged1 peptide in mandibular condylar cartilage, as a type of secondary cartilage. Mandibular condyle of ddY mice were fixed from embryonic day 15 (E15) through just after birth (equivalent to E19). Serial sections were examined using histological immunohistochemical (IHC) techniques. At E15, the proliferating cells had positive products of Jagged1 in their cytoplasms and cell membrane of almost all coagulating cells. At E17, cytoplasmic and membranuous reactions of Jagged1 factors appeared strongly in the cells just inside the condylar cartilage sheath. At E18, Jagged1 positive products were observed in almost all cells of the layers, and they were mostly distinct in the sheath of the condyle. At just after birth, Jagged1 was observed in a portion of almost all layer cells in their cytoplasm and membrane. These results suggest that Jagged1 plays an essential role for mandibular condylar cartilage morphogenesis and development.

Updated anatomy of the dermocartilaginous ligament of the nose

Pitanguy conducted a series of anatomic studies on the dermocartilaginous ligament of the nose. However, information on its structure is as yet insufficient. In addition, some of the histologic findings described by Pitanguy are controversial. The present study was undertaken to clarify the anatomy of the dermocartilaginous ligament. Sixteen cadaver noses were examined macroscopically and histologically to determine the presence, origin, insertion, composition, and relationship of the dermocartilaginous ligament with surrounding structures. There was no direct connection between the dermocartilaginous ligaments and dorsal nasal skin. This structure originated from the deep layer of the transverse nasalis muscle and terminated at the caudal edge of the septal cartilage and orbicularis oris muscle in some cases. Our histologic findings were incompatible with the use of the term ligament and demonstrated that it was in fact a fascia. Unlike Pitanguy's findings, no muscle fibers or chondrocytes were identified within the dermocartilaginous ligament.

Development and evolution of chordate cartilage

Deuterostomes are a monophyletic group of animals containing vertebrates, lancelets, tunicates, hemichordates, echinoderms, and xenoturbellids. Four out of these six extant groups-vertebrates, lancelets, tunicates, and hemichordates-have pharyngeal gill slits. All groups of deuterostome animals that have pharyngeal gill slits also have a pharyngeal skeleton supporting the pharyngeal openings, except tunicates. We previously found that pharyngeal cartilage in hemichordates and cephalochordates contains a fibrillar collagen protein similar to vertebrate type II collagen, but unlike vertebrate cartilage, the invertebrate deuterostome cartilages are acellular. We found SoxE and fibrillar collagen expression in the pharyngeal endodermal cells adjacent to where the cartilages form. These same endodermal epithelial cells also express Pax1/9, a marker of pharyngeal endoderm in vertebrates, lancelets, tunicates, and hemichordates. In situ experiments with a cephalochordate fibrillar collagen also showed expression in pharyngeal endoderm, as well as the ectoderm and the mesodermal coelomic pouches lining the gill bars. These results indicate that the pharyngeal endodermal cells are responsible for secretion of the cartilage in hemichordates, whereas in lancelets, all the pharyngeal cells surrounding the gill bars, ectodermal, endodermal, and mesodermal may be responsible for cartilage formation. We propose that endoderm secretion was primarily the ancestral mode of making pharyngeal cartilages in deuterostomes. Later the evolutionary origin of neural crest allowed co-option of the gene network for the secretion of pharyngeal cartilage matrix in the new migratory neural crest cell populations found in vertebrates.

Phylogenetic relationships of the Lake Tanganyika cichlid tribe Lamprologini: The story from mitochondrial DNA

The Lamprologini are the most species-rich and diverse tribe of Lake Tanganyika cichlids, comprising around 90 described species. We reconstruct the most complete ( approximately 70 species) mtDNA phylogeny to date for this tribe, based on NADH dehydrogenase subunit 2 (ND2 approximately 1047 bp) and the non-coding control region ( approximately 874 bp) and examine the degree to which mtDNA trees are good proxies for species trees. Phylogenetic relationships are assessed using Bayesian inference, maximum likelihood and maximum parsimony to determine the robustness of relationships. The resulting topologies are largely congruent and only the tree produced by an unpartitioned BI analysis is rejected using the non-parametric likelihood-based AU test. The trees are remarkably balanced, with two major clades consistently recovered in all analyses and with reasonable support. A smaller clade of deep-water species is also recovered. Overall support is good, when compared to some groups that have undergone adaptive radiation and rapid lineage formation. The much-expanded phylogeny of the group helps resolve the placement of some previously problematic taxa, such as Neolamprologus moori, highlighting the importance of greater taxonomic sampling. The results include a number of divergent placements of closely related species, and the following genera Neolamprologus, Lamprologus, Julidiochromis, Telmatochromis are not monophyletic, with alternative hypotheses consistent with traditional taxonomy providing a significantly worse fit to the data. We find several examples of divergent mtDNA taxa sequences of presumed closely related species. This could be due to incorrect taxonomy or to the failure of the mtDNA to reflect species relationships and may support the hypothesis that speciation within this group has been facilitated by introgressive hybridisation.

A two-color acid-free cartilage and bone stain for zebrafish larvae

Traditionally, cartilage is stained by alcian blue using acidic conditions to differentiate tissue staining. The acidic conditions are problematic when one wishes to stain the same specimen for mineralized bone with alizarin red, because acid demineralizes bone, which negatively affects bone staining. We have developed an acid-free method to stain cartilage and bone simultaneously in zebrafish larvae. This method has the additional advantage that PCR genotyping of stained specimens is possible.

The relationship between the angle of the trochlear groove and patella cartilage and bone morphology--a cross-sectional study of healthy adults

OBJECTIVES

Although the geometry of the trochlear groove is considered important in the pathogenesis of patellofemoral joint pathology it is unclear how the shape of the trochlear groove relates to patella morphology. This cross-sectional study investigated the relationship between the shape of the trochlear groove and patella cartilage and bone morphology in healthy adults.

METHODS

Two hundred and ninety-seven healthy adults aged between 50 and 79 years with no clinical history of knee pain or pathology were examined using magnetic resonance imaging (MRI). From the magnetic resonance (MR) images, the bony angles formed at the distal and proximal trochlear groove were measured, together with patella cartilage and bone volumes and patella cartilage defects.

RESULTS

After adjustment for potential confounders, there was an 8.70mm(3) (95% confidence interval (CI) 2.15, 15.26) increase in patella cartilage volume (P=0.009), with no increased prevalence of cartilage defects (odds ratio=0.99 (95% CI 0.96, 1.02), P=0.35), for every 1 degrees increase (i.e., as the angle became more flatter) at the distal trochlear groove. Moreover, there was a 53.86mm(3) (95% CI -90.26, -17.46) reduction in patella bone volume for every 1 degrees that the angle at the distal trochlear groove became more flattened (P=0.004). No significant association between the proximal trochlear groove angle and the patella cartilage or bone properties was observed.

CONCLUSION

A more flattened bony angle at the distal trochlear groove was associated with increased patella cartilage volume and reduced patella bone volume, but no increased prevalence of patella cartilage defects in adults with no history of knee pain or clinical disease. These cross-sectional findings suggest that a flattened distal trochlear groove may protect against degenerative patellofemoral conditions, such as osteoarthritis, but this will need to be confirmed in a longitudinal study.

Confocal arthroscopy-based patient-specific constitutive models of cartilaginous tissues - II: prediction of reaction force history of meniscal cartilage specimens

The theoretical framework developed in a companion paper (Part I) is used to derive estimates of mechanical response of two meniscal cartilage specimens. The previously developed framework consisted of a constitutive model capable of incorporating confocal image-derived tissue microstructural data. In the present paper (Part II) fibre and matrix constitutive parameters are first estimated from mechanical testing of a batch of specimens similar to, but independent from those under consideration. Image analysis techniques which allow estimation of tissue microstructural parameters form confocal images are presented. The constitutive model and image-derived structural parameters are then used to predict the reaction force history of the two meniscal specimens subjected to partially confined compression. The predictions are made on the basis of the specimens' individual structural condition as assessed by confocal microscopy and involve no tuning of material parameters. Although the model does not reproduce all features of the experimental curves, as an unfitted estimate of mechanical response the prediction is quite accurate. In light of the obtained results it is judged that more general non-invasive estimation of tissue mechanical properties is possible using the developed framework.

Effects of formalin fixation and collagen cross-linking on T2 and magnetization transfer in bovine nasal cartilage

Endogenous collagen cross-links influence cartilage biomechanical properties and resistance to degradation. Formalin fixation modifies collagen residues and forms new cross-links in a dose-dependent manner. We tested the hypothesis that magnetization transfer (MT) effects and T(2) depend on collagen cross-linking in cartilage. These parameters were measured in bovine nasal cartilage (BNC) prior to fixation, after 9 weeks of immersion in formalin solutions ranging in concentration from 0% to 10%, and after NaBH(3)CN reduction and washing. T(2) decreased by 59.4% +/- 1.1% upon fixation in 10% formalin, and was 32.2% +/- 5.2% shorter than initial values after washing. The apparent MT rate increased 25.9% +/- 3.7% and 52.8% +/- 7.1% over baseline under these conditions. Biochemical assays showed no significant differences in water, proteoglycan, natural cross-link, or collagen content between the 0% and 10% formalin-treated samples, while amino acid analysis demonstrated losses in (hydroxy)lysine and tyrosine, and new peaks consistent with methylene cross-links in fixed samples only. We conclude that formalin fixation of cartilage results in significant decreases in T(2) and increases in MT parameters that persist after removal of unreacted formaldehyde. The collagen cross-links thus created are associated with large changes in MT and T(2), indicating that interpretation of T(2) and MT values in terms of cartilage macromolecular content must be made with caution.

Confocal arthroscopy-based patient-specific constitutive models of cartilaginous tissues—I: development of a microstructural model

Current development of a laser scanning confocal arthroscope within our school will enable 3D microscopic imaging of joint tissues in vivo. Such an instrument could be useful, for example, in assessing the microstructural condition of the living tissues without physical biopsy. It is envisaged also that linked to a suitable microstructural constitutive formulation, such imaging could allow non-invasive patient-specific estimation of tissue mechanical performance. Such a procedure could have applications in surgical planning and simulation, and assessment of engineered tissue replacements, where tissue biopsy is unacceptable. In this first of two papers the development of a suitable constitutive framework for generating such estimates is reported. A microstructure-based constitutive formulation for cartilaginous tissues is presented. The model extends existing fibre composite-type models and accounts for strain-rate sensitivity of the tissue mechanical response through incorporation of a viscoelastic fibre phase. Importantly, the model is constructed so as to allow direct incorporation of structural data from confocal images. A finite element implementation of the formulation suitable for incorporation within commercial codes is also presented.

Quantification of intervertebral disc volume properties below spine fusion, using magnetic resonance imaging, in adolescent idiopathic scoliosis surgery

STUDY DESIGN

Prospective clinical study. A quantification of volume and hydration variation of the intervertebral discs, using magnetic resonance imaging (MRI), in the lumbar spine before and after surgery performed in adolescent idiopathic scoliosis (AIS).

OBJECTIVES

To evaluate an objective quantification of volume and hydration of intervertebral discs below spine fusion in scoliosis surgery.

SUMMARY AND BACKGROUND DATA

Repercussion of long spine fusion on the free lower lumbar spine is one of the major concerns of scoliosis surgery. However, the evolution of lumbar intervertebral disc below thoracolumbar fusions remains unknown.

METHODS

MRI performed in the clinical protocol, concerned 28 patients having an idiopathic scoliosis. They underwent posterior instrumentations. MRI was obtained before surgery, after surgery at 3 months and for 15 patients at 1 year. MRI data were posttreated using a custom-made image processing software to semiautomatically derive volume properties of disc, anulus fibrosus, and nucleus pulposus. The nucleus-disc volume ratio was also an indicator of the hydration level.

RESULTS

The reliability of the three-dimensional reconstruction process was initially verified using an intraoperator reproducibility test. Original preoperative data on disc volume properties were then derived. Postoperative volume variations were quantified in discs below spine fusion taking into account the level of the arthrodesis and the disc location. It showed that the postoperative volume criteria increased significantly for nucleus, disc, and nucleus-disc volume ratio and some magnitude modulation could be conditioned by the location of surgical instrumentation. Some stabilization or reduction depending on disc level and arthrodesis size between 3 months and 1 year is observed in the follow-up. It tended to prove that the recovery of balance physiologic positioning and inherent biomechanical loads could induce a restored hydration of disc, which should favor the remodeling of free segments.

CONCLUSIONS

This work was the first report dealing with consequences of scoliosis surgery on subjacent disc in term of volume and hydration properties.

Optimal methods for the preservation of cartilage samples in MRI and correlative biochemical studies

MRI studies of cartilage require the prevention of sample degradation before and during scanning and during shipment for correlative studies. Methods to achieve this include immersion in protease inhibitors (PIs), refrigeration, and freezing. In this study, bovine nasal cartilage (BNC) samples were stored in Dulbecco's phosphate-buffered saline (DPBS), DPBS with standard PIs, or PI solution with GM6001, a potent metalloproteinase inhibitor. For each buffer, three samples were scanned at +4 degrees C and stored at +4 degrees C or at -20 degrees C with thawing prior to imaging. T2 and magnetization transfer (MT) rate, km, were measured weekly over 4 months, after which time water and glycosaminoglycan (GAG) contents were compared with those of matching tissue excised pre-storage. Samples in DPBS exhibited increased T2 (+33.6% after 1 month at +4 degrees C, P = 0.040) and decreased km (-20.6%, P = 0.004), while refrigeration in DPBS with PI and GM6001 yielded good stability (T2: +2.7%, P = 0.874; km: -4.2%, P = 0.654 after 108 days at +4 degrees C). Water content increased while GAG content markedly decreased in all samples. Thus, stability in cartilage MRI parameters can be optimized with appropriate storage conditions, but storage time should nonetheless be minimized.

Histological structure of the nasal cartilages and their perichondrial envelope. I. The septal and lobular cartilage

The cellular elements and extracellular matrix of the nasal septal cartilage and the lateral crus of the lobular cartilage were studied in serial coronal sections of five human cadaver noses. To discern the various tissue components, the sections were stained according to the methods of Mallory-Cason, Azan, Herovici, Verhoeff-van Gieson, and Lawson as well as by immunohistochemistry to demonstrate the presence of collagen type I and II. A characteristic gradual transition of the chondrocytes was observed in both septal and lobular cartilage: from numerous small flat cells oriented parallel to the surface of the cartilage to less numerous larger ovaloid cells oriented perpendicular to the surface. This difference between the peripheral and central zones of the cartilage was particularly marked in lobular cartilage. Both septal and lobular cartilage have a high density of type II collagen but almost none of type I. The peripheral zones of the matrix showed a higher density of collagen than the central zone. This difference was more pronounced in septal than lobular cartilage. The high density of type II collagen in septal cartilage, particularly in the peripheral zones, suggests that one of the primary tasks of the septum is providing stiffness to the external nose. That idea is consistent with findings from our study of the perichondrial envelope.

Histological structure of the nasal cartilages and their perichondrial envelope. II. The perichondrial envelope of the septal and lobular cartilage

The perichondrial envelopes of the septal cartilage and the lateral crus of the lobular cartilage were studied in serial coronal sections of five human noses. To differentiate between the various tissue components, the sections were stained according to Mallory-Cason, Azan, Herovici, Verhoeff-van Gieson, and Lawson. Collagen types I and II were immunohistochemically stained. The results demonstrated that the perichondrium of the septal cartilage and the lateral crus of the lobular cartilage consists of a homogeneous layer of type I collagen fibers and elastic fibers. The elastic fibers have a network-like arrangement and are most numerous in the perichondrium of the lateral crus of the lobular cartilage. Clearly distinguishable zones in the perichondrial envelopes could not be observed. The perichondrium on the outside of the lateral crus of the lobular cartilage and the triangular cartilage is significantly thicker than the inner perichondrium. It is speculated that these morphological characteristics of the perichondrial envelopes are related to functional differences between the cartilages. The mobility of the lateral crus of the lobular cartilage requires a higher content of elastic fibers in its perichondrium than the more rigid septal cartilage. A thicker outer perichondrium of the lateral crus of the lobular cartilage and the triangular cartilage may be related to muscular forces that are exerted on the outer side of the cartilages only.

Should in the treatment of osteochondritis dissecans biodegradable or metallic fixation devices be used? A comparative study in goat knees

Most of the metallic devices have to be removed, treating osteochondritis dissecans lesions. This animal study describes the biological and mechanical behavior of screws and pins, made of commercially available PGA/PLA and PLA96 and metallic screws and pins, used for fragment fixation. A sham operation served as control. A tissue reaction with cavity formation was observed around every PGA/PLA screw, beginning at 12 weeks following insertion, in contrast to once around a PLA96 screw (p < 0.001), once around one of the 16 PGA/PLA pins and never around those, made of PLA96 (no significance). Disintegration of the PGA/PLA devices started 6 weeks following implantation against 34 weeks for the PLA96 implants. The gap between the fragment and the recipient cartilage disappeared only in the sham group. Many fragments of PGA/PLA material were found in the synovia, in contrast with just a few fragments in the PLA96 group, causing a mild cellular reaction. No polymer particles were found in the draining lymph nodes at any interval. In conclusion, the tested biodegradable screws should not be used for fragment fixation in the treatment of osteochondritis dissecans. Either an undesirable tissue reaction can be expected (PGAPLA), or, because of the slow degradation (PLLA), a screw might damage the opposite cartilage during weight bearing. Two biodegradable pins provide a safe rotational stability and should be combined with one metallic screw, providing compression. This screw has to be removed before loading the limb to prevent cartilage wear of the opposite tibia plateau.

Histological and histomorphometric investigation of the condylar cartilage of juvenile pigs after anterior mandibular displacement

The condylar cartilage of the mandible is considered a secondary growth center and represents a joint cartilage different from other cartilage structures regarding its histological structure, its histochemical and immunohistochemical properties and its growth pattern. This study aimed to histologically and histomorphometrically investigate the condylar cartilage after anterior mandibular displacement similar to functional orthopedic treatment. A total of 12 pigs (sus scrofa domesticus) aged 10 weeks were divided into an experimental group and a control group comprising 6 animals each. The experimental animals were provided bilaterally with synthetic occlusal build-ups in the posterior area which induced anterior displacement of the mandible in terminal occlusion. After 4 weeks, the temporomandibular structures were removed en bloc and the condylar cartilage was analyzed histologically and histomorphometrically. As a result, the experimental animals displayed a significantly increased total cartilage thickness of the posterocranial mandibular condyle which was primarily caused by an increase in thickness of the hypertrophic and chondogenic layers. Similarly, the proliferative layer showed a significant increase, whereas significant differences in thickness were absent in the articular layer. Increased cell proliferation was not observed in the experimental animals as compared to the controls. The changes found in the condylar cartilage area suggest that the zonal structure of the condylar cartilage may be modified by an altered spatial relationship between the mandibular condyle and the glenoid fossa.

Ultra-high-field MRI of the musculoskeletal system at 7.0T

High-field (3T) and ultra-high-field (UHF, 7T and above) systems are increasingly being used to explore potential musculoskeletal applications because they provide a high intrinsic signal-to-noise ratio (SNR), potentially higher resolution (spatial and temporal), and improved contrast. However, imaging at 7T and above presents certain challenges, such as homogeneous radiofrequency (RF) coil design, increased chemical shift artifacts, susceptibility artifacts, RF energy deposition, and changes in relaxation times compared to more typical clinical scanners (1.5 and 3T). Despite these issues, MRI at 7T likely will provide some excellent opportunities for high-resolution morphologic imaging and forays into functional imaging of musculoskeletal systems. In this review we address some of these issues and also demonstrate the feasibility of acquiring high-resolution in vivo images of the musculoskeletal system in healthy human volunteers at 7.0T.

Morphological features of cartilage observed during mandibular distraction in rabbits

Ossification during distraction osteogenesis can be classified as intramembranous or endochondral. It is not known whether cartilage in the distraction gap is transformed into new bone. The aim of this study was to investigate the morphological features of ossification in the transition of cartilage to bone during mandibular distraction osteogenesis in a rabbit model. A cortical osteotomy was performed and custom-made devices were applied. Immediately after surgery, the devices were lengthened by 0.25 mm every 12h for up 10 days, during which time four rabbits were killed at 0, 5 and 10 days and examined using histological staining and immunohistochemical methods. Apoptotic cells were identified by an in-situ detection assay for nuclear DNA fragmentation using a modified TUNEL procedure, with several sections analyzed using software for histomorphometric analysis. The results showed that the amount of cartilage in the distraction gap was significantly decreased. The cartilage had ossified in two ways, termed endochondral ossification and transchondroid bone formation.

Endochondral ossification in vitro is influenced by mechanical bending

Bone development is influenced by the local mechanical environment. Experimental evidence suggests that altered loading can change cell proliferation and differentiation in chondro- and osteogenesis during endochondral ossification. This study investigated the effects of three-point bending of murine fetal metatarsal bone anlagen in vitro on cartilage differentiation, matrix mineralization and bone collar formation. This is of special interest because endochondral ossification is also an important process in bone healing and regeneration. Metatarsal preparations of 15 mouse fetuses stage 17.5 dpc were dissected en bloc and cultured for 7 days. After 3 days in culture to allow adherence they were stimulated 4 days for 20 min twice daily by a controlled bending of approximately 1000-1500 microstrain at 1 Hz. The paraffin-embedded bone sections were analyzed using histological and histomorphometrical techniques. The stimulated group showed an elongated periosteal bone collar while the total bone length was not different from controls. The region of interest (ROI), comprising the two hypertrophic zones and the intermediate calcifying diaphyseal zone, was greater in the stimulated group. The mineralized fraction of the ROI was smaller in the stimulated group, while the absolute amount of mineralized area was not different. These results demonstrate that a new device developed to apply three-point bending to a mouse metatarsal bone culture model caused an elongation of the periosteal bone collar, but did not lead to a modification in cartilage differentiation and matrix mineralization. The results corroborate the influence of biophysical stimulation during endochondral bone development in vitro. Further experiments with an altered loading regime may lead to more pronounced effects on the process of endochondral ossification and may provide further insights into the underlying mechanisms of mechanoregulation which also play a role in bone regeneration.

Histomorphology of the mandibular condylar cartilage in greater galagos (Otolemur spp.)

The functional morphology of the primate craniomandibular complex and temporomandibular joint (TMJ) components is frequently discussed in terms of gross skeletal structure. At the histomorphologic level, however, the TMJ has only been studied in Old World anthropoids. The present study is designed to describe the microanatomy of the condylar cartilage of the TMJ in two closely related species of greater galago: the exudativorous Otolemur crassicaudatus and the frugivorous O. garnettii. TMJs with intact joint capsules were harvested from adult, cadaveric specimens of these species (four O. crassicaudatus and five O. garnettii). The samples were decalcified, processed for paraffin sectioning, and sectioned at 10-18 microm in the coronal plane. The samples were then stained with hematoxylin/eosin, Gomori trichrome, and Alcian blue, and examined with a photomicroscope. Generally, condylar cartilage in O. crassicaudatus was thickest both laterally and centrally, while O. garnettii had the relatively thickest cartilage laterally. Both species displayed a superficial articular zone, a middle proliferative zone, and a deeply located hypertrophic zone in the condylar cartilage. O. crassicaudatus typically had the greatest cell density in each of these zones. In addition, O. crassicaudatus had focal concentrations of Alcian blue laterally and centrally, while O. garnettii had the greatest reactivity in the central portion only. These results suggest that O. crassicaudatus may be specialized to resist greater compressive force at the TMJ condylar cartilage in specific regions of the mandibular condyle.

High-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T: Comparison of surface coil and volume coil

PURPOSE

To evaluate high-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T using a surface coil (SC) or volume coil (VC).

MATERIALS AND METHODS

MRI was obtained from nine volunteers in the supine position with a 3-inch SC and in prone position with a transmit-receiver wrist VC at 3 T. Coronal two-dimensional-gradient echo (2D-GRE) images (TR/TE/FA = 500 msec/15 msec/40 degrees , 1 mm slice-thickness, 60 mm field of view [FOV], 192 x 256 matrix) and coronal 3D-GRE images (TR/TE/FA = 33 msec/15 msec/10 degrees , 0.8 mm slice-thickness, 80 mm FOV, 256 x 256 matrix) were used. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the TFCC and surrounding structures were measured. For qualitative measurement, visualization of TFCC and intercarpal ligaments was graded.

RESULTS

SNR of TFCC, cartilage, and bone marrow on 2D-GRE with SC/VC was as follows: 5.3/5.3 (TFCC), 16.5/14.4 (cartilage), and 3.61/3.96 (bone marrow). 3D-GRE showed similar SNR. Cartilage-TFCC/cartilage-bone marrow CNR were 11.1/12.8 (SC-2D-GRE), 8.8/10.5 (VC-2D-GRE), 14.1/15.5 (SC-3D-GRE), and 11.9/15.0 (VC-3D-GRE). Quantitative values were not significantly different between SC and VC. Visualization of TFCC and intercarpal ligament with SC was superior to that with VC. All structures show higher scores with 3D-GRE imaging compared to 2D-GRE imaging.

CONCLUSION

SC may provide superior qualitative and quantitative results and can be an alternative in case of difficulty in prone position at 3T.

Cranial ontogeny inPhilautus silus (Anura: Ranidae: Rhacophorinae) reveals few similarities with other direct-developing anurans

Direct development has evolved in rhacophorine frogs independently from other anuran lineages, thereby offering an opportunity to assess features associated with this derived life history. Using a developmental series of the direct-developing Philautus silus (Ranidae: Rhacophorinae) from Sri Lanka, we examine features of cranial morphology that are part of a suite of adaptations that facilitate feeding in free-living tadpoles, but have been changed or lost in other direct-developing lineages. Larval-specific upper jaw cartilages, which are absent from many non-rhacophorine direct-developing species (such as Eleutherodactylus coqui), develop in embryos of P. silus. Similarly, lower jaw cartilages initially assume a larval morphology, which is subsequently remodeled into the adult jaw configuration before hatching. However, the cartilaginous jaw suspension and hyobranchial skeleton never assume a typical larval morphology. The palatoquadrate, which suspends the lower jaw, lacks the posterior connections to the braincase found in many metamorphosing species. Unlike in metamorphosing species, bone formation in P. silus begins before hatching. However, the sequence of bone formation resembles that of metamorphosing anurans more than that of other direct developers. In particular, P. silus does not exhibit precocious ossification of the lower jaw, which is characteristic of some frogs and caecilians that lack a free-living tadpole. These data reveal some similarities between Philautus and other direct-developing anurans. However, the departure of Philautus embryos from the generalized tadpole skeletal morphology is less pronounced than that observed in other direct-developing taxa.

An alternative Alcian Blue dye variant for the evaluation of fetal cartilage

BACKGROUND

The most comprehensive evaluation of vertebrate skeletal development involves the use of Alizarin Red S dye to stain ossified bone and various other dyes to stain cartilage. The dye used most widely to stain fetal cartilage in rodents and rabbits is Alcian Blue 8GX. However, the global supply of this specific dye has been exhausted. Several forms of the dye marketed as Alcian Blue 8GX are now available, although they are not synthesized via the original 8GX manufacturing process.

METHODS

One new Alcian Blue 8GX form and two Alcian Blue dye variants were evaluated in rats and rabbits using standard staining procedures. The staining quality of these dyes were evaluated relative to the original form of Alcian Blue 8GX based on cartilage uptake of the dye, clarity of the cartilaginous components, staining intensity of the dye, and overall readability of the specimens under stereomicroscopic evaluation.

RESULTS

Staining with the newer form of Alcian Blue 8GX resulted in poor staining quality. The Alcian Blue-Pyridine variant performed well, although staining intensity was less than optimal. The Alcian Blue-Tetrakis variant provided staining characteristics that were most similar to the original form of Alcian Blue 8GX.

CONCLUSIONS

Alcian Blue-Tetrakis was markedly better in its ability to stain fetal cartilage than the newer form of Alcian Blue 8GX.

Morphological alterations in the growth plate cartilage of ovariectomized mice

The effects of ovariectomy on growth and estrogen receptor (ER) expression level in the epiphyseal growth plate in mice have been estimated by histomorphometry and immunohistochemistry. Twelve female ddY mice, 8-9 weeks of age, were subjected to bilateral ovariectomy and 12 others were sham operated. They were then killed 8 weeks later. Ovariectomy significantly increased the total thickness of the distal femoral and proximal tibial growth plate cartilage. Ovariectomy caused a 1.4-fold increase in the thickness of the proliferative layer in the distal growth plate of the femur and a 1.3-fold increase in the thickness of the proliferative layer in the proximal growth plate of the tibia. ERalpha and ERbeta immunoreactivity was detected in chondrocytes of the growth plate and the expression level of ERs in epiphyseal plates was increased in ovariectomized mice compared with controls. These data suggest that ERalpha and ERbeta are coexpressed in the growth plates of the mice and that the cartilage growth and the level of expression of ERs in these tissues are hormonally regulated.