Abnormal Segmentation Research Articles

A neonate with an anomalous bone attached to the cervical spine

Background contextA digit/rib-like ectopic bone is a rare congenital anomaly that is most commonly seen in the thorax or pelvis. There is a single report of an adult possessing a phalanx-like bone in the cervical region; however, whether the abnormal bone was congenital or acquired remains elusive. PurposeTo elucidate that a phalanx-like bone in the cervical region represents a congenital anomaly. Study designCase report. MethodsReport of the imaging findings in a neonate with a palpable bone projection in the posterior neck. ResultsPlain radiographs demonstrated an ectopic bone posterior to the spinous process of the C5 vertebra. Three-dimensional computed tomography demonstrated that the anomalous bone was attached to the left lamina of the C5 vertebra and that there was abnormal segmentation of the left side of the cervical spine. ConclusionsThe anomalous bone in the neck is a congenital malformation that is accompanied by the maldevelopment of the cervical spine.

Mir-125a-5p-Mediated Regulation of Lfng Is Essential for the Avian Segmentation Clock

Somites are embryonic precursors of the axial skeleton and skeletal muscles and establish the segmental vertebrate body plan. Somitogenesis is controlled in part by a segmentation clock that requires oscillatory expression of genes including Lunatic fringe (Lfng). Oscillatory genes must be tightly regulated at both the transcriptional and posttranscriptional levels for proper clock function. Here, we demonstrate that microRNA-mediated regulation of Lfng is essential for proper segmentation during chick somitogenesis. We find that mir-125a-5p targets evolutionarily conserved sequences in the Lfng 3' UTR and that preventing interactions between mir-125a-5p and Lfng transcripts in vivo causes abnormal segmentation and perturbs clock activity. This provides strong evidence that microRNAs function in the posttranscriptional regulation of oscillatory genes in the segmentation clock. Further, this demonstrates that the relatively subtle effects of microRNAs on target genes can have broad effects in developmental situations that have critical requirements for tight posttranscriptional regulation.

Distance metric-based time-efficient fuzzy algorithm for abnormal magnetic resonance brain image segmentation

Image segmentation is one of the significant computational applications of the biomedical field. Automated computational methodologies are highly preferred for medical image segmentation since these techniques are immune to human perception error. Artificial intelligence (AI)-based techniques are often used for this process since they are superior to other automated techniques in terms of accuracy and convergence time period. Fuzzy systems hold a significant position among the AI techniques because of their high accuracy. Even though these systems are exceptionally accurate, the time period required for convergence is exceedingly high. In this work, a novel distance metric-based fuzzy C-means (FCM) algorithm is proposed to tackle the low-convergence-rate problem of the conventional fuzzy systems. This modified approach involves the concept of distance-based dimensionality reduction of the input vector space that substantially reduces the iterative time period of the conventional FCM algorithm. The effectiveness of the modified FCM algorithm is explored in the context of magnetic resonance brain tumor image segmentation. Experimental results show promising results for the proposed approach in terms of convergence time period and segmentation efficiency. Thus, this algorithm proves to be highly feasible for time-oriented real-time applications.

Bilateral cerebellopontine angle lipomas

Cerebellopontine angle (CPA) lipomas are extremely rare lesions and usually unilateral. We describe a case of a 36-year-old man with bilateral aural fullness that was discovered to have bilateral CPA lipomas associated with an abnormal hindbrain segmentation appearance. The patient was evaluated with 3.0T magnetic resonance imaging (MRI) system. MRI demonstrated the presence of bilateral CPA masses partially extending into the internal auditory canals. These lesions were hyperintense on both T1- and T2 weighted images. Facial and vestibulo-cochlear nerves together with tortuous vascular structures and fibro-connective septa were identified on T2-weighted 3D Fast Imaging Employing Steady-state Acquisition (FIESTA) sequences as areas of lower intensity coursing through the masses. Gadolinium administration yielded no enhancement. Conservative management was adopted.

The agrochemical fungicide triadimefon induces abnormalities in Xenopus laevis embryos

The dysmorphogenic activity of the triazole fungicide triadimefon (FON) has been evaluated using Xenopus laevis development. Embryos, exposed to 500 μM FON during early neurulation phases (stages 13–17, Nieuwkoop and Faber), were allowed to develop until stage 47. Larvae revealed serious craniofacial defects, bent forebrain, and abnormal hindbrain segmentation. CRABP and CYP26 (markers related to retinoic acid homeostasis) gene and protein expression and protein distribution have been evaluated at stage 17 and at the end of the branchial arch morphogenesis (stage 27) by real-time PCR, western blot and whole-mount immunostaining. A significant increase of CYP26 transcript has been observed at both embryonic stages. A co-localization of the two markers has been observed at the cephalic region. Embryos exposed to FON showed abnormal distribution of positive tissues. Due to the strict similarity of these results with those previously described in rodents, a FON-related alteration of mechanism conserved during vertebrate evolution is suggested.

Unusual spine anatomy contributing to wrong level spine surgery: a case report and recommendations for decreasing the risk of preventable 'never events'.

BackgroundWrong site surgery is one of five surgical "Never Events," which include performing surgery on the incorrect side or incorrect site, performing the wrong procedure, performing surgery on the wrong patient, unintended retention of a foreign object in a patient, and intraoperative/immediate postoperative death in an ASA Class I patient. In the spine, wrong site surgery occurs when a procedure is performed on an unintended vertebral level. Despite the efforts of national safety protocols, literature suggests that the risk for wrong level spine surgery remains problematic.Case PresentationA 34-year-old male was referred to us to evaluate his persistent thoracic pain following right-sided microdiscectomy at T7-8 at an outside institution. Postoperative imaging showed the continued presence of a herniated disc at T7-8 and evidence of a microdiscectomy at the level immediately above. The possibility that wrong level surgery had occurred was discussed with the patient and revision surgery was planned. During surgery, the site of the previous laminectomy was clearly visualized; however, we also experienced confusion when verifying the level of the previous surgery. We ultimately used the previous laminectomy site as a landmark for identifying and treating the correct pathologic level. Postoperative consultation with Musculoskeletal Radiology revealed the patient had two abnormalities in his spinal anatomy that made intraoperative counting of levels inaccurate, including a pair of cervical ribs at C7 and the absence of a pair of thoracic ribs.ConclusionThis case highlights the importance of strict adherence to a preoperative method of vertebral labeling that focuses on the landmarks used to label a pathologic disc space, rather than simply relying on the reference to a particular level. That is, by designating the pathological level as the disc space associated with the fourth rib up from the last rib-bearing vertebrae, rather than calling it "T7-8", then the correct level can be found intraoperatively even in the case of abnormal segmentation. We recommend working closely with radiology during preoperative planning to identify unusual anatomy that may have been overlooked. We also recommend that radiology colleagues use the same system of identifying pathological levels when dictating their reports. Together, these strategies can reduce the risk of wrong level surgery and increase patient safety.

17β-estradiol에 노출된 저서성 요각류 Tigriopus japonicus s.l.의 세대간 생활사 및 형태학적 변이 연구

To characterize ecotoxicological responses to a natural estrogen, 17β-estradiol, we evaluated the life-history of the parental (F?) and first generation (F₁) of the harpacticoid copepod, Tigriopus japonicus sensu lato. We evaluated the survival of nauplii and copepodites, the number of days until the emergence of copepodites and adult males, the sex ratio, brooding success, and the first brooding day of adult females. No significant differences in the survival rate were noted in response to treatments with different concentrations of 17β-estradiol. However, 17β-estradiol induced developmental delay and skewed the sex ratio toward males. Copepod development was delayed significantly in the 0.1 and 1 ㎍ l ?1 17β-estradiol treatment groups relative to the control group, with a more pronounced delay in the F1 group. Body length and biomass were significantly smaller in the 17β-estradiol treated groups than in the controls. The male emergence of T. japonicus s.l. was very high in the 10 and 30 ㎍ l ?1 17β-estradiol treatment group. Furthermore, exposure to 17β-estradiol resulted in morphological deformities such as shrinking and swelling of the urosome, twisted setae of the caudal rami, setal loss of swimming legs, abnormal segmentation of antennules, and dwarfism.

Notch inhibition by the ligand Delta-Like 3 defines the mechanism of abnormal vertebral segmentation in spondylocostal dysostosis

Mutations in the DELTA-LIKE 3 (DLL3) gene cause the congenital abnormal vertebral segmentation syndrome, spondylocostal dysostosis (SCD). DLL3 is a divergent member of the DSL family of Notch ligands that does not activate signalling in adjacent cells, but instead inhibits signalling when expressed in the same cell as the Notch receptor. Targeted deletion of Dll3 in the mouse causes a developmental defect in somite segmentation, and consequently vertebral formation is severely disrupted, closely resembling human SCD. In contrast to the canonical Notch signalling pathway, very little is known about the mechanism of cis-inhibition by DSL ligands. Here, we report that Dll3 is not presented on the surface of presomitic mesoderm (PSM) cells in vivo, but instead interacts with Notch1 in the late endocytic compartment. This suggests for the first time a mechanism for Dll3-mediated cis-inhibition of Notch signalling, with Dll3 targeting newly synthesized Notch1 for lysosomal degradation prior to post-translational processing and cell surface presentation of the receptor. An inhibitory role for Dll3 in vivo is further supported by the juxtaposition of Dll3 protein and Notch1 signalling in the PSM. Defining a mechanism for cis-inhibition of Notch signalling by Dll3 not only contributes greatly to our understanding of this ligand's function during the formation of the vertebral column, but also provides a paradigm for understanding how other ligands of Notch cis-inhibit signalling.

Integrated analysis of clinical signs and literature data for the diagnosis and therapy of a previously undescribed 6p21.3 deletion syndrome

A de novo 0.3 Mb deletion on 6p21.3 was detected by array-comparative genomic hybridization in a girl with mental retardation, drug-resistant seizures, facial dysmorphisms, gut malrotation and abnormal pancreas segmentation. Consistent with phenotypic manifestations is haploinsufficiency of SYNGAP1, which was recently demonstrated to cause non-syndromic mental retardation, and of the flanking genes CuTA, a likely modulator of the processing and trafficking of secretory proteins in the human brain, and hPHF1, involved in HOX gene silencing. Mutations of both CuTA and hPHF1 were never reported as causative of human diseases. Similarly, the present syndromic condition was not previously described and it can be regarded as a human model confirming the suggested biological properties of the genes included in the deletion interval. In addition, experimental evidence that SYNGAP1 and CuTA are involved in the secretory pathway in neurons, through glutamate and acetylcholinesterase signalling, prompted us to consider modulation of the glutamate pathway as target of a therapeutic strategy for seizure control.

The Association Analysis of TBX6 Polymorphism With Susceptibility to Congenital Scoliosis in a Chinese Han Population

A case-control association study was conducted to investigate the genetic etiology for congenital scoliosis (CS) in a Chinese Han population. To identify whether TBX6 polymorphisms are associated with susceptibility to CS in a Chinese Han population. CS is a 3-dimensional deformity of the spine, resulting from defection of normal vertebral development. Although there are many types of defects observed in CS, all result from abnormal formation and segmentation of the vertebral precursors, called somites. Developmental studies in animal models have identified many genes regulating somite formation and segmentation. T-box factor, TBX6, is a prerequisite for somite segmentation in vertebrates. In mouse TBX6 knockouts, the phenotypes are similar with that of some human birth defects, such as CS, raises the possibility that TBX6 gene may be a potential susceptibility gene for CS, so we investigated the relations between TBX6 polymorphisms and CS. Two known single-nucleotide polymorphisms (SNPs) of TBX6 gene were genotyped among 254 Chinese Han subjects (127 CS patients and 127 controls with matched sex and age) by GenomeLab SNPstream genotyping system. The 2 markers (the only tagging SNP and a functional SNP) with minor allele frequency above 5% were analyzed by the allelic and genotypic association analysis, the genotype-phenotype (CS patients were divided into type I 31 cases [failure of formation], type II 46 cases [a failure of segmentation], and type III 50 cases [mixed defects]) association analysis, and the haplotype analysis. The single SNP analysis showed allele frequency of rs2289292 (exon 8, the only tagging SNP) and rs3809624 (5' untranslated region) demonstrated significant difference between CS cases and controls (P = 0.017 and P = 0.033). No SNP was found to be correlated with clinical phenotype. Moreover, the 2 makers (rs2289292 and rs3809624) in TBX6 gene were found to be in strong linkage disequilibrium (D' = 1.0; gamma = 0.984; 95% confidence interval, 0.96-1.0; LOD = 57.48) in the controls. Both global haplotype analysis and individual haplotype analysis showed that the haplotype of SNP1/SNP2 showed significant association with the disease (P = 0.017), G-A haplotype was more frequently observed in controls than in cases (odds ratio, 0.71; 95% confidence interval, 0.51-0.99). This is the first report on SNPs of TBX6 gene in CS that suggests genetic variants of TBX6 gene is associated with CS and may play an important role in mediating susceptibility to developing CS in the Chinese Han population.

Visualization of skeletons and intervertebral disks in live fish larvae by fluorescent calcein staining and disk specific GFP expression

Zebrafish and medaka have become popular models for studying skeletal development because of high fecundity, shorter generation period, and transparency of fish embryo. The first step to study skeletal development is visualizing bone and cartilage. Live animal staining with fluorescent calcein have several advantages over the standard skeletal staining protocol by using alizarin red and alcian blue for bone and cartilage. However, there is no detailed study examining skeletal development of live marine fish larvae by calcein staining. Here we applied calcein staining to examine skeletal development in red sea bream larvae. In addition, green fluorescent protein (GFP) reporter zebrafish was employed to trace lineage analysis of intervertebral disk cells in live fish larvae. Calcein staining of red sea bream larvae successfully visualized development of craniofacial skeletons as well as urinary calculus. Histochemical detection of alkaline phosphatase (ALP) activity revealed that abnormal segmentation of notochord induced by RA during vertebral development in zebrafish. Immunohistochemistry clearly revealed that GFP-positive cells in intervertebral space was nucleus polposus like cell in twhh-GFP transgenic zebrafish. It was demonstrated usefulness of calcein and ALP staining and twhh-GFP transgenic zebrafish for studying skeletal development in live fish larvae.

Two novel missense mutations in HAIRY-AND-ENHANCER-OF-SPLIT-7 in a family with spondylocostal dysostosis

Spondylocostal dysostosis (SCD) is an inherited disorder with abnormal vertebral segmentation that results in extensive hemivertebrae, truncal shortening and abnormally aligned ribs. It arises during embryonic development by a disruption of formation of somites (the precursor tissue of the vertebrae, ribs and associated tendons and muscles). Four genes causing a subset of autosomal recessive forms of this disease have been identified: DLL3 (SCDO1: MIM 277300), MESP2 (SCDO2: MIM 608681), LFNG (SCDO3: MIM609813) and HES7 (SCDO4). These genes are all essential components of the Notch signalling pathway, which has multiple roles in development and disease. Previously, only a single SCD-causative missense mutation was described in HES7. In this study, we have identified two new missense mutations in the HES7 gene in a single family, with only individuals carrying both mutant alleles being affected by SCD. In vitro functional analysis revealed that one of the mutant HES7 proteins was unable to repress gene expression by DNA binding or protein heterodimerization.

Zygotic VegT is required for Xenopus paraxial mesoderm formation and is regulated by Nodal signaling and Eomesodermin

The T-box gene VegT plays a crucial role during mesendoderm specification of the amphibian embryo. While the function of maternal VegT (mVegT) has been extensively investigated, little is known about the function and transcriptional regulation of zygotic VegT (zVegT). In the present study, we used comparative genomics and a knockdown experiment to demonstrate that zVegT is the orthologous gene of zebrafish Spadetail/Tbx16 and chick Tbx6L/Tbx6, and has an essential role in paraxial mesodermal formation. zVegT knockdown embryos show several defects in the patterning of trunk mesoderm, such as abnormal segmentation of somites, a reduction in muscle, and the formation of an abnormal mass of cells at the tail tip. We also identified the cis-regulatory elements of zVegT that are necessary and sufficient for mesoderm-specific expression. These cis-regulatory elements are located in two separate upstream regions of zVegT, corresponding to the first intron of mVegT. The results of in vitro binding and functional assays indicate that Forkhead box H1 (FoxH1) and Eomesodermin (Eomes) are the trans-acting factors required for zVegT expression. Our results highlight the essential role of zVegT in organization of paraxial mesoderm, and reveal that zVegT is regulated by a coherent feedforward loop of Nodal signaling via Eomes.

Anomalous segmentation of Diphyllobothrium nihonkaiense

An anomalous tapeworm with abnormal segmentation was obtained from a 6-year-old boy in Japan. The tapeworm consisted of proglottids with slanted anterior and posterior margins of proglottids and 4–6 sets of reproductive organs arranged between the margins. The morphology of the tapeworm did not correspond to any of the described cestodes. However, molecular identification based on nuclear and mitochondrial genes clearly showed the tapeworm was Diphyllobothrium nihonkaiense.

The Endo-siRNA Pathway Is Essential for Robust Development of the Drosophila Embryo

BackgroundRobustness to natural temperature fluctuations is critical to proper development in embryos and to cellular functions in adult organisms. However, mechanisms and pathways which govern temperature compensation remain largely unknown beyond circadian rhythms. Pathways which ensure robustness against temperature fluctuations may appear to be nonessential under favorable, uniform environmental conditions used in conventional laboratory experiments where there is little variation for which to compensate. The endo-siRNA pathway, which produces small double-stranded RNAs in Drosophila, appears to be nonessential for robust development of the embryo under ambient uniform temperature and to be necessary only for viral defense. Embryos lacking a functional endo-siRNA pathway develop into phenotypically normal adults. However, we hypothesized that small RNAs may regulate the embryo's response to temperature, as a ribonucleoprotein complex has been previously shown to mediate mammalian cell response to heat shock.Principal FindingsHere, we show that the genes DICER-2 and ARGONAUTE2, which code for integral protein components of the endo-siRNA pathway, are essential for robust development and temperature compensation in the Drosophila embryo when exposed to temperature perturbations. The regulatory functions of DICER-2 and ARGONAUTE2 were uncovered by using microfluidics to expose developing Drosophila embryos to a temperature step, in which each half of the embryo develops at a different temperature through developmental cycle 14. Under this temperature perturbation, dicer-2 or argonaute2 embryos displayed abnormal segmentation. The abnormalities in segmentation are presumably due to the inability of the embryo to compensate for temperature-induced differences in rate of development and to coordinate developmental timing in the anterior and posterior halves. A deregulation of the length of nuclear division cycles 10–14 is also observed in dicer-2 embryos at high temperatures.ConclusionsResults presented herein uncover a novel function of the endo-siRNA pathway in temperature compensation and cell cycle regulation, and we hypothesize that the endo-siRNA pathway may regulate the degradation of maternal cell cycle regulators. Endo-siRNAs may have a more general role buffering against environmental perturbations in other organisms.

Spondylocarpotarsal synostosis: A rare case of vertebral segmentation defect

Spondylocarpotarsal synostosis (SS) is a disorder of abnormal vertebral segmentation. Clinically manifest as kyphoscoliosis/scoliosis with characteristic radiographic findings vertebral, carpal and tarsal bone fusion. It is inherited as an autosomal recessive disorder. The present study report a case of SS and describe the clinical and radiological manifestations. In addition to classical signs, neuroimaging revealed cervical spine abnormalities, further supporting the importance of spine imaging in such cases.

Examination of the Newborn With Congenital Scoliosis

Although scoliosis at birth is rare, conditions at birth and in the newborn period predispose newborns to the development of scoliosis in later life. Scoliosis is congenital when associated with abnormal vertebral segmentation regardless of the age of diagnosis. Other conditions may predispose neonates to vertebral damage or the development of sustained uneven forces on the developing spine. Although it is difficult to know which newborns will progress to developing scoliosis, it is important to be aware of risk factors to provide anticipatory education for parents and to arrange appropriate follow-up after discharge. This article reviews the embryology of vertebral formation and risk factors for the development of scoliosis. The discussion includes the incidence, risk factors, genetics, associated problems, physical examination, and nursing implications of the infant with congenital scoliosis.

Expression cloning in Xenopus identifies RNA‐binding proteins as regulators of embryogenesis and Rbmx as necessary for neural and muscle development

We have performed an expression cloning screen in Xenopus laevis with the aim of isolating novel gene activities from the neural plate. Of 8,064 clones screened, we isolated 61 clones that affected either neural plate patterning or tadpole morphology. Of these, 20 clones encoded RNA binding proteins, and the majority of these are heterogeneous nuclear ribonucleoproteins (hnRNPs) or SR-proteins, which are associated with alternative splicing. All of these genes are expressed in the nervous system, and in several cases specific to neural tissue. Injecting mRNA encoding these proteins results in neural plate mispatterning and abnormal muscle segmentation. To initiate characterization of these proteins, we selected Rbmx as a candidate for deeper analysis. Using morpholino mediated knockdown, we show that Rbmx is necessary for normal anterior neural plate patterning, neurogenesis, neural crest development, and muscle segmentation.

Mutations in the MESP2 Gene Cause Spondylothoracic Dysostosis/Jarcho-Levin Syndrome

Spondylothoracic dysostosis (STD), also known as Jarcho-Levin syndrome (JLS), is an autosomal-recessive disorder characterized by abnormal vertebral segmentation and defects affecting spine formation, with complete bilateral fusion of the ribs at the costovertebral junction producing a "crab-like" configuration of the thorax. The shortened spine and trunk can severely affect respiratory function during early childhood. The condition is prevalent in the Puerto Rican population, although it is a panethnic disorder. By sequencing a set of candidate genes involved in mouse segmentation, we identified a recessive E103X nonsense mutation in the mesoderm posterior 2 homolog (MESP2) gene in a patient, of Puerto Rican origin and from the Boston area, who had been diagnosed with STD/JLS. We then analyzed 12 Puerto Rican families with STD probands for the MESP2 E103X mutation. Ten patients were homozygous for the E103X mutation, three patients were compound heterozygous for a second nonsense mutation, E230X, or a missense mutation, L125V, which affects a conserved leucine residue within the bHLH region. Thus, all affected probands harbored the E103X mutation. Our findings suggest a founder-effect mutation in the MESP2 gene as a major cause of the classical Puerto Rican form of STD/JLS.

Expanded clinical spectrum of spondylocarpotarsal synostosis syndrome and possible manifestation in a heterozygous father

We report on a 5-year-old boy with spondylocarpotarsal synostosis (SCT) syndrome who presents with disproportionate short stature, thoracic scoliosis, pes planus, dental enamel hypoplasia, unilateral conductive hearing loss and mild facial dysmorphisms. Radiographs showed abnormal segmentation of the spine with block vertebrae and carpal synostosis. In addition to the typical phenotype of SCT syndrome, he showed pronounced delay of carpal bone age and bilateral epiphyseal dysplasia of the proximal femora. The patient's father has mild short stature and unilateral hip dysplasia. Molecular studies of the filamin B gene (FLNB) revealed a homozygous mutation in the index patient while both parents were heterozygous for the mutation. In this report we expand the phenotype of SCT syndrome in a patient with a causal FLNB mutation.