Posterior Lamina Research Articles

Spectral-Domain Optical Coherence Tomography Enhanced Depth Imaging of the Normal and Glaucomatous Nonhuman Primate Optic Nerve Head

To test whether the enhanced depth imaging (EDI) modality improves anterior and posterior lamina cribrosa surface (ALCS and PLCS) visibility compared with conventional spectral-domain optical coherence tomography (SD-OCT). Conventional and EDI SD-OCT scans were obtained 30 minutes after IOP was manometrically lowered to 10 mm Hg in both eyes of 14 nonhuman primates (NHPs) with unilateral experimental glaucoma (EG). Thirteen horizontal and seven vertical radial B-scans of each SD-OCT data set were delineated by one operator masked to image type. Delineated ALCS and PLCS points were projected to 1 of 100 equal-sized subregions of the neural canal opening (NCO) reference plane, and the number of delineated subregions (≥2 points) was counted. Poisson regression was used to analyze the effects of image type, treatment, and quadrant. Two additional delineations were performed for three NHPs to compare reproducibility. EDI increased the number of subregions delineated for both the ALCS (by 28%; P < 0.0001) and PLCS (by 225%; P < 0.0001). EDI improvement in ALCS visibility was significant in the superior quadrant only and was not different in EG versus control eyes, whereas EDI improvement in PLCS visibility was significant in all four quadrants (P < 0.005) and greater in EG eyes (P < 0.001), nasally and temporally. Intradelineator reproducibility was not different between image types. EDI and standard ONH parameter values were similar except for PLCS depth which was deeper in the EDI data sets (P = 0.0002). ALCS and PLCS visibility within control and EG NHP ONHs increased in EDI compared to conventional SD-OCT data sets. Further study of EDI effects on PLCS parameterization is required.

IOP-Induced Lamina Cribrosa Deformation and Scleral Canal Expansion: Independent or Related?

To study the association between the intraocular pressure (IOP)-induced anterior-posterior lamina cribrosa deformation (LCD) and scleral canal expansion (SCE). 3D eye-specific models of the lamina and sclera of the eyes of three normal monkeys were constructed. Morphing techniques were used to produce 768 models with controlled variations in geometry and materials. Finite element analysis was used to predict the LCD and SCE resulting from an increase in IOP. We analyzed the association between LCD and SCE for the population as a whole, and for subsets. For some conditions, such as deep and stiff lamina, the association between LCD and SCE was strong and consistent with the concept of "the sclera pulls the lamina taut" as IOP increases. For other conditions, such as shallow and compliant lamina, there was no association. Further, for other conditions, such as for thin and stiff sclera, the association was opposite to the tautening. Although most of the models had similar response to IOP, some cases had peculiarly large LCD and SCE. The properties of the lamina cribrosa (LC) greatly influenced its response to variations in IOP; for example, deep laminas tended to displace anteriorly, whereas shallow LCs displaced little or posteriorly. The association between LCD and SCE varied greatly depending on the properties of the lamina and sclera, which shows that it is critical to consider the characteristics of the population when interpreting measurements of LCD and SCE. This work is the first systematic analysis of the relationship between LCD and SCE.

New information on the anatomy and systematic position of Dinheirosaurus lourinhanensis (Sauropoda: Diplodocoidea) from the Late Jurassic of Portugal, with a review of European diplodocoids

Although diplodocoid sauropods from Africa and the Americas are well known, their European record remains largely neglected. Here we redescribe Dinheirosaurus lourinhanensis from the Late Jurassic of Portugal. The holotype comprises two posterior cervical vertebrae, the dorsal series and a caudal centrum. Redescription demonstrates its validity on the basis of three autapomorphies: (1) posteriorly restricted ventral keel on posterior cervical vertebrae; (2) three small subcircular fossae posterior to the lateral coel on posterior cervical neural spines; (3) accessory lamina linking the hyposphene with base of the posterior centrodiapophyseal lamina in middle-posterior dorsal vertebrae. Phylogenetic analysis places Dinheirosaurus as the sister taxon to Supersaurus, and this clade forms the sister taxon to other diplodocines. However, this position should be treated with caution as Dinheirosaurus displays several plesiomorphic features absent in other diplodocids (including unbifurcated presacral neural spines, and dorsolaterally projecting diapophyses on dorsal vertebrae) and only four additional steps are required to place Dinheirosaurus outside of Flagellicaudata. We identify Amazonsaurus as the basal-most rebbachisaurid and recover Zapalasaurus outside of the South American Limaysaurinae, suggesting the biogeographic history of rebbachisaurids is more complex than previously proposed. Review of the European diplodocoid record reveals evidence for the earliest known diplodocid, as well as additional diplodocid remains from the Late Jurassic of Spain. A Portuguese specimen, previously referred to Dinheirosaurus, displays strong similarities to Apatosaurus from the contemporaneous Morrison Formation of North America, indicating the presence of a second Late Jurassic Portuguese diplodocid taxon. Along with Dinheirosaurus, these Portuguese remains provide further evidence for a Late Jurassic palaeobiogeographic connection between Europe and North America. No dicraeosaurids are currently known from Europe, but rebbachisaurids are present in the Early Cretaceous, with weak evidence for the earliest known representative from the Late Jurassic of Spain; however, more complete material is required to recognize early members of this clade.

Partial cricotracheal resection with tracheal intussusception and cricoarytenoid joint mobilization: Early experience in a new technical variant

Partial cricotracheal resection with tracheal intussusception and cricoarytenoid joint mobilization: Early experience in a new technical variant

Clinical evaluation of indirect decompression treatments for degenerative adult idiopathic scoliosis

Prospective case series. Degenerative idiopathic scoliosis can be a cause of back pain. We sought to explore the feasibility and effectiveness of indirect decompression treatment in posterior correction and fusion for adult idiopathic scoliosis patients with radiculopathy and combined lateral olisthesis and/or foraminal stenosis. Thirty seven degenerative adult idiopathic scoliosis patients with radiculopathy were recruited. Prostration or body traction alleviated the neurological deficit in these patients. Their symptoms were aggravated, when patients stood up. Imaging was used to assess lateral olisthesis and/or foraminal stenosis. All patients underwent posterior pedicle screw fixation, deformity correction, dorsal lamina and posterolateral bone grafting with the indirect decompression treatment. Clinical examinations including visual analog scale (VAS), oswestry disability index (ODI) scores, and images were performed pre- and post-operation and during follow-up visits. Twenty seven patients were followed for the average of 30.8months. No serious complication was observed. The cobb's angle, lateral olisthesis, thoracic kyphosis, thoracolumbar kyphosis, lumbar lordosis, VAS and ODI scores, coronal and sagittal balance were significantly improved among the patients who underwent the indirect decompression treatment. All patients had eliminated neurological deficit at their final follow-ups. The indirect decompression treatment in the posterior correction and fusion can be effective for adult idiopathic scoliosis patients with radiculopathy and combined lateral olisthesis and/or foraminal stenosis. This indicates the premise of strict operation indication.

Hirayama disease: An uncommon cause of distal upper extremity deficit

Hirayama disease is a myelopathy related to flexion movements of the neck that produce ischemic damage in the anterior horn of the cervical cord. The disease affects young people and is characterized by a distal upper extremity deficit that develops gradually. The diagnosis is confirmed by cervical magnetic resonance imaging (MRI) in flexion demonstrating a forward shift of the posterior dural sac and spinal cord compression. On radiology, there should be suggestive signs in neutral position such as cord atrophy, intramedullary bilateral high signal intensity on T2-weighted images, straightening of the cervical spine, and loss of attachment between the posterior dural sac and subjacent lamina. Exploration should be completed by an MR study in neck flexion. We report here on two typical cases of the disease and also include a review of the literature.

Morphometric Characteristics of Central Retinal Artery and Vein Endothelium in the Normal Human Optic Nerve Head

This study documents the morphometric features of arterial and venous endothelia in the different laminar regions of the normal human optic nerve head and speculates on the hemodynamic characteristics of the central retinal artery (CRA) and central retinal vein (CRV). Twenty normal human eyes were used. Microcannulation techniques were used to label the cytoskeleton and nuclei of endothelial cells in the CRA and CRV, after which images were captured using confocal microscopy. Length, width, length-to-width ratio, and area measurements were obtained from endothelium and its nuclei. Nucleus position with respect to cell apex and direction of blood flow was also quantified. Comparisons were made between prelaminar, anterior lamina cribrosa, posterior lamina cribrosa, and retrolaminar regions. Venous and arterial endothelial cell morphology was also compared. There was significant variation in venous endothelial morphology across the different laminar regions; however, no differences were found in arterial endothelial characteristics (all P > 0.1065). Significant differences were found between arterial and venous endothelium in all laminar regions apart from the posterior lamina cribrosa, where only nuclear area (P = 0.0001) and nucleus position (P = 0.0088) were found to be different. Arterial-like appearance of venous endothelium in the posterior lamina cribrosa, where pressure gradient forces are predicted to be greatest and CRV luminal diameter is known to be narrowest, implicates this as a site of altered hemodynamic stress. Heterogeneity of venous endothelium may have relevance for understanding ocular vascular diseases such as central retinal vein occlusion.

Laryngo-tracheo-oesophageal clefts

A laryngo-tracheo-esophageal cleft (LC) is a congenital malformation characterized by an abnormal, posterior, sagittal communication between the larynx and the pharynx, possibly extending downward between the trachea and the esophagus. The estimated annual incidence of LC is 1/10,000 to 1/20,000 live births, accounting for 0.2% to 1.5% of congenital malformations of the larynx. These incidence rates may however be underestimated due to difficulty in diagnosing minor forms and a high mortality rate in severe forms. A slightly higher incidence has been reported in boys than in girls. No specific geographic distribution has been found. Depending on the severity of the malformation, patients may present with stridor, hoarse cry, swallowing difficulties, aspirations, cough, dyspnea and cyanosis through to early respiratory distress. Five types of laryngo-tracheo-esophageal cleft have been described based on the downward extension of the cleft, which typically correlates with the severity of symptoms: Type 0 laryngo-tracheo-esophageal cleft to Type 4 laryngo-tracheo-esophageal cleft. LC is often associated with other congenital abnormalities/anomalies (16% to 68%), mainly involving the gastro-intestinal tract, which include laryngomalacia, tracheo-bronchial dyskinesia, tracheo-bronchomalacia (mostly in types 3 and 4), and gastro-esophageal reflux disease (GERD). The syndromes most frequently associated with an LC are Opitz/BBB syndrome, Pallister Hall syndrome, VACTERL/VATER association, and CHARGE syndrome. Laryngeal clefts result from failure of fusion of the posterior cricoid lamina and abnormal development of the tracheo-esophageal septum. The causes of the embryological developmental anomalies leading to LC are not known but are thought to be multifactorial. LC appears to be mostly sporadic although some familial cases with suspected autosomal dominant transmission have been reported. The age of diagnosis depends mainly on the severity of the clinical symptoms and therefore on the extent of the LC. Diagnosis is made either based on clinical manifestations or on investigations, such as endoscopy, X-ray, CT scan, performed for other conditions. Differential diagnoses include tracheo-bronchial fistula, gastro-esophageal reflux disease and neurological swallowing disorders, as well as laryngomalacia and laryngeal palsy. Prenatal diagnosis of LC has never been reported, although associated anomalies may be detected on fetal ultrasonography. Once the cleft is diagnosed, it is essential to determine its length to orient the management and treatment approach. Management involves maintenance of satisfactory ventilation, prevention of secondary pulmonary complications as a result of repeated aspirations, and adequate feeding. Endotracheal intubation may be required for respiratory distress in severe cases. Treatment requires endoscopic or external surgery to close the cleft. Surgery should be performed as early as possible to avoid complications related to aspiration and gastric reflux, except in type 0 and type 1 cases in which conservative measures must first be attempted. The prognosis is variable depending on the severity of the LC and associated malformations. Early diagnosis and appropriate treatment and management help to reduce mortality and morbidity.

Surgical strategy to dural ossification of thoracic spinal stenosis

Objective To explore the surgical strategies of thoracic spinal stenosis with dural ossification. Methods One-hundred and eight patients with thoracic spinal stenosis were treated. Dural ossification was found in 29 cases during operation from January 2004 to June 2008. There were 19 males and 10females, with an average age of 56.4 years （42-74 years）. The course of disease was 13 months （2-48months）. The lesion was located in T1-T4 in 4 cases, T5-T8 in 5 cases, and T9-T12 in 20 cases. All the patients were treated by posterior lamina resection. Both ossificated dural and ossificated yellow ligament were resected in 16 patients. Decompression was performed with partial ossification remaining on dural surface in 13 cases. JOA score was used to evaluate the outcomes 1, 3 and 12 months after operation. Results The average operation time was 140 min, and average bleeding was 300 ml. Dural incisions were repaired with a wound drainage in 11 cases. Seven cases appeared cerebrospinal fluid leakage which healed in 3-5 days.Dural incisions were not repaired without wound drainage in 5 cases. Cerebrospinal fluid leakage occurred in these cases healed in 5-7 days. Thirteen cases treated with floating method did not appear cerebrospinal fluid leakage. All patients did not undergo subarachnoid infection and the aggravation of original nervous system symptoms. According to JOA score, all patients were evaluated as excellent in 22 cases, good in 5 and fair in 2 cases, and excellent and good rate was 93%. Conclusion For thoracic spinal stenosis with dural ossification, resection of both ossificated dural and ossificated yellow ligament and complete decompression with partial ossification remaining on dural surface is safe and reliable. Dural ossification does not influence the prognosis, but increase operative difficulty and risk. Key words: Spinal stenosis; Ossification, heterotopic; Thoracic vertebrae

Reassessment of the vertebral laminae in some South American titanosaurian sauropods

ABSTRACT The neural spines of the sauropod presacral vertebrae contain a series of osseous laminae of unquestionable phylogenetic significance. However, the lack of articulated presacral series has impeded identification of these structures in many taxa. Titanosaur sauropods present a pattern of neural laminae that is somewhat different from other groups, especially to diplodocids. Understanding these differences is important in order to score adequately characters related to vertebral anatomy, in phylogenetic analyses of the Sauropoda. Particularly, many titanosaurs present two spinodiapophyseal laminae in the posterior dorsal vertebrae. Additionally, these taxa show the apparent disappearing of the postzygodiapophyseal lamina in those vertebrae. Other titanosaurs have a single posterior dorsal spinodiapophyseal lamina, but this probably corresponds to one (probably the anterior) of the two spinodiapophyseal laminae of the posterior dorsals of the other titanosaurs.

Glaucomatous cupping of the lamina cribrosa: A review of the evidence for active progressive remodeling as a mechanism

The purpose of this review is to examine the literature in an attempt to elucidate a biomechanical basis for glaucomatous cupping. In particular, this work focuses on the role of biomechanics in driving connective tissue remodeling in the progression of laminar morphology from a normal state to that of an excavated glaucomatous state. While there are multiple contributing factors to the pathogenesis of glaucoma, we focus on laminar extracellular matrix (ECM) remodeling in glaucoma and the feedback mechanisms and signals that may guide progressive laminar cupping. We review the literature on the potential mechanisms of glaucomatous changes in the laminar ECM at the anatomic, structural, cellular and subcellular levels in the context of the biomechanical paradigm of glaucomatous onset and progression. Several conclusions can be drawn from this review. First, extensive remodeling of the lamina cribrosa ECM occurs in primary open angle glaucoma. Second, there is surprisingly little evidence to support acute mechanical damage to the lamina as the principal mechanism of cupping. Third, ONH astrocytes and lamina cribrosa cells can sense their mechanical environment and respond to mechanical stimuli by remodeling the ECM. Fourth, there is evidence suggesting that chronic remodeling of the lamina results in a progressive posterior migration of the laminar insertion into the canal wall, which eventually results in the posterior lamina inserting into the pia mater. Finally, modeling studies suggest that laminar remodeling may be a biomechanical feedback mechanism through which cells modify their environment in an attempt to return to a homeostatic mechanical environment. It is plausible that biomechanics-driven connective tissue remodeling is a mechanism in the progression of laminar morphology from a normal state to that of a cupped, excavated glaucomatous state.

Swelling of the Human Cornea Revealed by High-Speed, Ultrahigh-Resolution Optical Coherence Tomography

To evaluate the change in thickness of the anterior, stromal, and posterior corneal laminae in response to hypoxia-induced corneal swelling, by means of ultrahigh-resolution optical coherence tomography (UHR-OCT). A UHR-OCT system, operating in the 1060-nm range, was used to acquire in vivo cross-sectional images of human cornea with a 3.2x10-microm (axial x lateral) resolution in corneal tissue. Corneal edema was induced by inserting a thick, positive-powered, soft contact lens, over which the eye was closed and patched for 3 hours. Tomograms were acquired from eight non-contact-lens wearers. Baseline images were obtained before inducing corneal edema, immediately after removal of the patch and the lens, and then every 15 minutes for approximately 2 hours. All images were postprocessed with a segmentation algorithm to identify the laminae visible in the image. The apical thickness of the laminae (epithelium [EPI], epithelial-Bowman's membrane [Ep-BM] complex, stroma, and endothelial-Descemet's membrane [En-DM] complex) were determined at each time interval. There was an interaction between time after removal of the hypoxic stimulus and deswelling of the layers (RM-ANOVA; P<0.001). The epithelial and stromal thickness reduced significantly with time (P=0.001; P<0.001, respectively), whereas the Ep-BM and En-DM complexes did not (P>0.50). All layers except the En-DM complex exhibited a biphasic pattern of recovery. UHR-OCT showed regional differences in swelling due to hypoxic provocation. On removal of the hypoxic stimulus, the rate of recovery varied between layers, and all layers except the En-DM complex exhibited a biphasic recovery.

Barrosasaurus casamiquelai gen. et sp. nov., a new titanosaur (Dinosauria, Sauropoda) from the Anacleto Formation (Late Cretaceous: early Campanian) of Sierra Barrosa (Neuquén, Argentina)

A new Late Cretaceous titanosaurian sauropod from the Sierra Barrosa locality (Anacleto Formation, Late Cretaceous, early Campanian) of Neuquén Province, Argentina, Barrosasaurus casamiquelai gen. et sp. nov., is described. The holotype of this species consists of three large and incomplete, although well-preserved, dorsal vertebrae (one probably the third, the next the seventh or eighth, and the last the ninth or tenth). The arrangement of neural arch laminae in the dorsal vertebrae of this titanosaur differs from that present in other genera in the following ways: the spinoprezygapophyseal laminae are well developed in the third vertebra, and relictual in the seventh or eighth vertebra; two spinodiapophyseal laminae are present in the seventh or eighth and in the ninth or tenth vertebrae, the anterior spinodiapophyseal lamina being more strongly developed than the posterior spinodiapophyseal lamina in the ninth or tenth vertebra. These characters, among others, allow the recognition of this individual as a new species of Titanosauria, which increases knowledge of the diversity of titanosaurs in the Late Cretaceous of Patagonia.

Segmental muscular atrophy of the distal upper extremity (Hirayama disease): An atypical case with anterior dural detachment

Segmental non-progressive spinal muscular atrophy of the upper extremity, also known as Hirayama disease (HD), is a disorder seen mainly in young male patients of Asian ancestry. On MRI loss-of-attachment between the posterior dural sac and adjacent lamina has been described as the only significantly important predictor of HD. We herein present a patient with HD who showed an atypical anterior detachment of the dura mater from the adjacent vertebral body.

Histomorphometric measurements in human and dog optic nerve and an estimation of optic nerve pressure gradients in human

Intraocular pressure and cerebrospinal fluid (CSF) pressure are important determinants of the trans-laminar pressure gradient which is believed to be important in the pathogenesis of glaucomatous optic nerve degeneration. Computational models and finite element calculations of optic nerve head biomechanics have been previously used to predict pressures and stresses in the human optic nerve. The purpose of this report is to morphometrically compare the optic nerve laminar and pia mater structure between humans and dogs, and to use previously reported tissue pressure measurements in the dog optic nerve to estimate individual-specific human optic nerve pressures and pressure gradients. High resolution light microscopy was used to acquire quantitative histological measurements from sagittal sections taken from the middle of the optic nerve in 34 human cadaveric eyes and 10 dog eyes. Parameters measured included the pre-laminar and lamina cribrosa thickness, distance from posterior boundary of lamina cribrosa to inner limiting membrane (ILM), shortest distance between anterior lamina cribrosa surface and subarachnoid space, shortest distance between ILM and inner surface of pia mater in contact with the subarachnoid space and optic nerve diameter. Pia mater thickness in the proximal 4 mm of post-laminar nerve was also determined. There was no significant difference in lamina cribrosa thickness between dog and human eyes (P = 0.356). The distance between the intraocular and subarachnoid space was greater in dogs (P < 0.001). Pia mater thickness was greatest at the termination of subarachnoid space in both species. In humans, pia mater thickness decreased over the proximal 500 μm to reach a constant value of approximately 60 μm. In dogs this decrease occurred over 1000 μm to reach a constant diameter of approximately 30 μm. Using previous measurements of optic nerve pressures and pressure gradients in dogs we estimate that at an IOP of 15 mmHg and a CSF pressure of 0 mmHg the mean pressure difference across the human pia mater will be 4.8 ± 2.2 mmHg. If we assume that the pressure difference between the intraocular space and post-laminar tissue falls across the entire thickness of the human lamina cribrosa then an estimate of the trans-laminar pressure gradient is 2.0 ± 0.8 mmHg/100 μm. If we assume that this pressure difference only occurs across the dense collagenous plates of the posterior lamina cribrosa then a trans-laminar pressure gradient high estimate of 3.3 ± 1.4 mmHg/100 μm is calculated. Changes in tissue pressure gradients in the optic nerve may be an important factor in the pathogenesis of glaucomatous optic neuropathy.

Posterior Commissure of the Human Larynx Revisited

The existence of the posterior commissure (PC) of the human larynx has been disputed (Hirano M, Sato K, et al. The posterior glottis. Trans Am Laryngol Assoc. 1986;107:70-75). "The term posterior commissure has no relevance to anatomical structure. The term commissure means a joining together. The bilateral vocal folds never join at their posterior ends. The posterior aspect of the glottis is a wall. The posterior lateral aspect of the posterior glottis is also the lateral wall of the posterior glottis" (Hirano M, Sato K, et al. The posterior glottis. Trans Am Laryngol Assoc. 1986;107:70-75). This study is intended to clarify the development of anatomical and morphological aspects of the PC in conjunction with a clinical classification of the larynx in sagittal view. This study uses human embryo and fetal laryngeal sections from the Carnegie Collection of Human Embryos (the world standard) and whole organ laryngeal sections from the Tucker Laryngeal Fetal Collection. Correlation of histologic and gross anatomical structure is made with the Hirano et al atlas, the Vidić Photographic Atlas of the Human Body, and the O'Rahilly Embryonic Atlas. Embryologic data clearly describe and illustrate the posterior union of the cricoid cartilage with formation of the PC. The anatomical functional aspects of the posterior lateral cricoid lamina as the supporting buttress of the articulating arytenoid cartilages are illustrated.

Cytopathology of Bombyx mori (Lepidoptera: Bombycidae) silk gland caused by multiple nucleopolyhedrovirus

A multiple nucleopolyhedrovirus previously isolated from infected Bombyx mori L. larvae (BmMNPV) in Paraná state, Brazil, was inoculated into B. mori larvae to examine susceptibility and cytopathology in silk gland cells. The anterior, middle and posterior silk glands were removed from the infected silkworm at different times post-inoculation and processed for cytopathology studies by light and transmission electron microscopy. BmMNPV infection was only detected at 72 h post-inoculation in cells of the middle and posterior silk glands. No sign of infection was found in the anterior silk gland. Cytopathological characteristics were similar to those found in other target tissues; initially, they consisted of nuclear hypertrophy and the formation of virogenic stroma (viroplasm), in which the progeny virions are produced. The virions are then enveloped and occluded in protein crystal structures, the polyhedra. After viral replication, cells undergo lysis and release a great number of BmMNPV polyhedra into the hemocoele. Histopathology showed early infection foci in regions surrounding trachea insertions, demonstrating that trachea is an infection-spreading organ in the insect body. Trachea penetrates the middle and posterior silk gland basal lamina, considered a barrier to virus, facilitating the penetration of budded virus. The anterior silk gland does not have tracheal insertions into the basal lamina, which reduces budded virus infection. Tracheal branches provide a conduit for non-occluded virions (budded virus) to pass through the basal lamina barrier and disseminate BmMNPV in the silkworm silk gland.

Evolutionary origin and development of snake fangs

Many advanced snakes use fangs-specialized teeth associated with a venom gland-to introduce venom into prey or attacker. Various front- and rear-fanged groups are recognized, according to whether their fangs are positioned anterior (for example cobras and vipers) or posterior (for example grass snakes) in the upper jaw. A fundamental controversy in snake evolution is whether or not front and rear fangs share the same evolutionary and developmental origin. Resolving this controversy could identify a major evolutionary transition underlying the massive radiation of advanced snakes, and the associated developmental events. Here we examine this issue by visualizing the tooth-forming epithelium in the upper jaw of 96 snake embryos, covering eight species. We use the sonic hedgehog gene as a marker, and three-dimensionally reconstruct the development in 41 of the embryos. We show that front fangs develop from the posterior end of the upper jaw, and are strikingly similar in morphogenesis to rear fangs. This is consistent with their being homologous. In front-fanged snakes, the anterior part of the upper jaw lacks sonic hedgehog expression, and ontogenetic allometry displaces the fang from its posterior developmental origin to its adult front position-consistent with an ancestral posterior position of the front fang. In rear-fanged snakes, the fangs develop from an independent posterior dental lamina and retain their posterior position. In light of our findings, we put forward a new model for the evolution of snake fangs: a posterior subregion of the tooth-forming epithelium became developmentally uncoupled from the remaining dentition, which allowed the posterior teeth to evolve independently and in close association with the venom gland, becoming highly modified in different lineages. This developmental event could have facilitated the massive radiation of advanced snakes in the Cenozoic era, resulting in the spectacular diversity of snakes seen today.

Clinical diagnosis and surgical treatment of congenital contractural arachnodactyly: analysis of 6 cases

To discuss the clinical diagnosis and surgical treatment of congenital contractural arachnodactyly (CCA). The clinical data of 6 CCA patients, 1 male and 5 female, aged 7.5 (5-14) were analyzed. All cases had kyphoscoliosis, 2 in the thoracic segments and 4 in the thoracolumbar segments. The average scoliosis Cobb angle was 88.6 degrees (85 degrees-117 degrees). The average kyphosis Cobb angle was 93.6 degrees (75 degrees-123 degrees). All of the cases underwent internal fixation with pedicle screw and lamina hooks instrumentation, in which 4 cases underwent posterior Smith-Petersen osteotomy. The diagnosis was based on a constellation of clinical findings. The clinical manifestations included marfanoid habitus, flexion contractures of multiple joints (elbow, knee, hip, and finger), kyphoscoliosis, muscular hypoplasia, and abnormal pinnae ("crumpled" outer helices). Molecular genetic testing showed mutation in the fibrillin-2 (FBN2) gene encoding the extracellular matrix microfibril. Four cases were followed up for 6-9 months. After operation the average Cobb angle of the scoliosis and kyphosis were 37.6 degrees (35 degrees-52 degrees) and 38.6 degrees (28 degrees-54 degrees) immediately, with 62.3% and 68.7% curve correction respectively. Three cases got excellent synostosis of posterior lamina, 1 case underwent revision with lamina hook because the distal screw was loose and hurt the nerve root, and the other 2 cases lost follow-up. The patients' body appearance and pulmonary function were obviously improved. The characteristic clinical manifestation include severe and stiff kyphoscoliosis, difficult to correct , and enhanced Cobb angle, and pedicle dysplasia of vertebral pedicle leading to difficulty in installing screws. Smith-Petersen osteotomy is often necessary. CCA should be differentiated with Marfan syndrome (MFS), Stickler syndrome, Homocystinuria, and distal arthrogryposis, especially MFS.

The reverse turnover latissimus dorsi flap for closure of midline lumbar defects

The surgical treatment of wounds located in the median lumbar area is difficult. When occurring after neurosurgical procedures, they may display a high level of complexity because of dural exposure, deep irregular three-dimensional contours, and bacterial contamination of the wound. The difficulty of reconstruction in that region of the body is made greater by the few possible regional flaps available in the vicinity. In order to obtain well-vascularised tissue, with good resistance to bacterial contamination and easy to shape into such defects, the reverse turnover latissimus dorsi flap is a useful surgical option. Between 1998 and 2003, four patients presented with complex lumbar wounds in our department. Three patients were adults (mean age: 63 years) and one patient was 1 year old. In all cases, reconstruction was needed in the lumbar area after surgery on the spine. All wounds presented with bacterial contamination. In three cases, dural exposure was present, while in the fourth case, a small remnant of the posterior vertebral bony lamina was still present after debridement. In all four cases, the reconstruction was successfully achieved by turning over the latissimus dorsi to reach the lumbar midline defect. In one case, the adult paraplegic patient, only the inferior part of the muscle was harvested, to preserve an innervated upper part of the muscle for upper limb function. In the four cases, long term results were excellent (the mean follow up was 3.5 years), with no residual infection.