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PubMed2006

Hypohidrotic ectodermal dysplasia (HED).

Hypohidrotic Ectodermal Dysplasia (HED) is a hereditary congenital disorder of ectodermal origin. It is characterized by lack of sweat glands (hypohidrosis), nail dystrophy(onychodysplasia), alopecia (hypotrichosis), defective palms and soles (palmoplantar hyperkeratosis) and the oral presentations of partial absence of teeth (hypodontia) or complete absence of teeth (anodontia). Hypodontia of primary and permanent dentition is one of the most frequently occurring oral symptoms in HED patients. These features of poor aesthetic affect the social and the psychological well-being of the patient. This case report describes the prosthetic rehabilitation of a HED patient.

Adolescent↗
PubMed2006

Ets2 is necessary in trophoblast for normal embryonic anteroposterior axis development.

Although the trophoblast is necessary for the growth, viability and patterning of the mammalian embryo, understanding of its patterning role is still rudimentary. Expression of the transcription factor Ets2 is restricted to the trophoblast in early postimplantation stages and Ets2 mutants have been previously shown to have defects in trophoblast development. We show here that Ets2 is necessary in the trophoblast for fundamental aspects of anteroposterior (AP) epiblast axis initiation, including mesoderm initiation at the primitive streak, establishment of posterior character in the epiblast and appropriate spatial restriction of the anterior visceral endoderm (AVE). Most homozygous Ets2 mutants also show highly reduced development of the trophoblast with an absence of extraembryonic ectoderm (EXE) markers. Embryos in which the EXE has been physically removed before culture in vitro phenocopy the patterning defects of Ets2 mutants. These defects cannot be rescued by providing Ets2 mutants with wild-type epiblast in tetraploid aggregations. Thus, EXE-derived signals are necessary for normal embryonic patterning. Ets2 is likely to be required in the EXE downstream of epiblast signals, such as Fgf, and, in turn, helps to regulate signals from the EXE that signal back to the epiblast to promote proper primitive streak and AVE development. This study provides new insights about the genetic and cellular basis of the patterning role and development of the early trophoblast.

Animals↗
PubMed2005

Identification of 14-3-3sigma mutation causing cutaneous abnormality in repeated-epilation mutant mouse.

Repeated-epilation (Er) mutation in the mouse is inherited as an autosomal and semidominant mutation. Major defects in heterozygous adults and homozygous fetuses were associated with skin and were caused by abnormal ectodermal differentiation. Heterozygous mice are characterized by repeated hair loss and regrowth, and homozygous fetuses die at birth with severe abnormality in skin, limb, tail, and face. To identify the gene causing Er mutation, we have performed gene-expression profiles of skins and mouse embryonic fibroblasts from WT and mutant Er mice by using Affymetrix (Santa Clara, CA) chip analysis. By analyzing the candidate genes generated from gene-expression profiling, we identified a Sfn mutation in Er mice. A single nucleotide insertion in the Sfn (Stratifin, also called 14-3-3sigma) coding region results in a truncated protein lacking 40 amino acid residues at the C terminus. The mutation is linked with phenotypes of Er-heterozygous and -homozygous mice. Ectopic overexpression of WT 14-3-3sigma in Er/Er keratinocytes rescues defects in keratinocyte differentiation. Our study demonstrates that 14-3-3sigma is a crucial regulator for skin proliferation and differentiation.

14-3-3 Proteins↗
PubMed2001

Xoom is maternally stored and functions as a transmembrane protein for gastrulation movement in Xenopus embryos.

Xoom has been identified as a novel gene that plays an important role in gastrulation of Xenopus laevis embryo. Although Xoom is actively transcribed during oogenesis, distribution and function of its translation product have not yet been clarified. In the present study, the polyclonal antibody raised against Xoom was generated to investigate a behavior of Xoom protein. Anti-Xoom antibodies revealed that there are two forms of Xoom protein in Xenopus embryos: (i) a 45 kDa soluble cytoplasmic form; and (ii) a 44 kDa membrane-associated form. Two forms of Xoom protein were ubiquitously detected from unfertilized egg to tadpole stage, with a qualitative peak during blastula and gastrula stages. Immunohistochemical examination showed that Xoom protein is maternally stored in the animal subcortical layer and divided into presumptive ectodermal cells during cleavage stages. Enzymatic digestion of membrane protein and immunologic detection of Xoom showed that Xoom exists as a membrane-associated protein. To examine a function of Xoom protein, anti-Xoom antibodies were injected into blastocoele of stage 7 blastula embryo. Anti-Xoom antibodies caused gastrulation defect in a dose- dependent manner. These results suggest that maternally prepared Xoom protein is involved in gastrulation movement on ectodermal cells.

Animals↗
PubMed1990

Trichothiodystrophy: review of sulfur-deficient brittle hair syndromes and association with the ectodermal dysplasias.

Trichothiodystrophy appears to represent a central pathologic feature of a specific hair dysplasia associated with several disorders in organs derived from ectoderm and neuroectoderm. The key finding is brittle hair with low sulfur content, but alternating dark and light bands under polarizing microscopy, trichoschisis, and absent or defective cuticle are additional important clues for the diagnosis of trichothiodystrophy. Our review of the literature revealed extensive associated findings in trichothiodystrophy. Classification of patients with trichothiodystrophy and other dysplasias is difficult because diminution of sulfur-rich protein in hair is not a sufficient marker to allow precise differentiation, although several similar ectodermal dysplasias can be excluded by demonstration of abnormal sulfur content in hair of patients with trichothiodystrophy. Patients with trichothiodystrophy should have a thorough evaluation for other associated manifestations, including investigation of photosensitivity and DNA repair defects. Detection of low-sulfur brittle hair syndrome is also important for genetic counseling because the disease appears to be inherited in an autosomal recessive pattern.

DNA Repair↗
PubMed1993

Histological study of the cranial neural folds of mice genetically liable to exencephaly.

The SELH/Bc (SELH) inbred stock of mice has a high liability to the neural tube closure defect, exencephaly. All SELH embryos close their cranial neural tubes by an abnormal mechanism, lacking elevation and initiation of fusion in the posterior prosencephalon/anterior mesencephalon region. Most embryos complete closure of the cranial neural tube by extension of a more rostral site of fusion, but in 10-20% this process fails, and the embryos are subsequently exencephalic. In this study, transverse histological sections of the cranial neural folds of SELH embryos at the 3-5, 6-8, and 9-11 somite stages were compared to those of two strains with normal neural tube closure, ICR/Bc and LM/Bc. At all stages, consistent morphological differences were observed between SELH and the two normal strains. In 3-5 somite SELH embryos, the divergence of the folds from the neural groove is more angular, the folds are flatter, and their lateral tips appear "hooked" downward. In 6-8 somite SELH embryos, the lateral tips of the folds appear more elongated and in the prosencephalon they are less elevated than in the normal strains. The boundary between neuroepithelium and mesenchyme or surface ectoderm tends to be less clear than normal in SELH lateral tips. In 9-11 somite SELH embryos, divergence of the folds from the neural groove continues to be angular and the lateral folds are splayed horizontally. In addition, the lateral surface ectoderm is abnormally indented and the neuroepithelium/surface ectoderm boundary is more ventral and lateral in SELH than in ICR/Bc and LM/Bc. The hypothesis that the defect in SELH cranial neural folds might involve the cytoskeleton was tested using a fluorescent probe for filamentous actin in 7 somite SELH and ICR/Bc embryos. The actin staining pattern in SELH embryos was like that of normal ICR/Bc embryos, with a strongly staining apical concentration in the neuroepithelium. This suggests that there is no gross cytological abnormality within the neuroepithelium, but does not rule out more subtle defects, such as those involving cytoskeletal function.

Animals↗
PubMed1983

Clouston syndrome: an ultrastructural study.

A previously undescribed French-Canadian family affected with Clouston Syndrome (Hypohidrotic Ectodermal Dysplasia) is described. Ultrastructural study of the hair shows disorganization of the hair fibrils with loss of the cuticular cortex. The SEM findings are consistent with the model, suggesting a biochemical defect in the keratin of the integumentary system.

Child↗
PubMed1992

Hypodontia, impacted permanent teeth, spinal defects, and cardiomegaly in a previously diagnosed case of the Yunis-Varon syndrome.

The Yunis-Varon syndrome is a rare hereditary disorder with ectodermal and skeletal anomalies that include agenesis or hypoplasia of the clavicles, craniofacial disproportion with severe micrognathia, digital anomalies, prenatal and postnatal growth deficiency, and neonatal death. Only 12 cases have been reported in the literature. Although neonatal death is a significant feature of this syndrome, two case reports describe children, both males, who were 30 months and 3 years of age at the time of investigation. The 30-month-old child was reexamined at 11 years of age, and had further clinical and radiologic features that included hypodontia, impacted permanent teeth, spinal defects, cardiomegaly, bilateral hearing loss, and metatarsus adductus. Children who survive the neonatal period and continue to thrive with many of the features of the Yunis-Varon syndrome as well as the new features described in this article may not have a distinct yet related syndrome.

Abnormalities, Multiple↗
PubMed2005

[Underlying causes of recurrent pneumonia].

OBJECTIVE: To determine the relative frequency and describe the predisposing causes of recurrent pneumonia in infants and children aged between 1 month and 14 years. METHODS: We retrospectively reviewed the medical records of a tertiary care pediatric hospital covering a 10-year period, from January 1994 through December 2003. Children with cystic fibrosis were not included in the analysis. Recurrent pneumonia was defined as at least two pneumonia episodes in a 1 year period or at least three episodes over a lifetime. RESULTS: Of 1644 children hospitalized with pneumonia, 106 (6.4 %) met the criteria for recurrent pneumonia. An underlying cause was identified in 92 patients (86.7 %). Of these, the underlying cause was diagnosed prior to pneumonia in 67 (72.8 %), during the first episode in 12 (13 %) and during recurrence in 13 (14.1 %). Underlying causes included asthma in 28 patients (30.4 %), congenital cardiac defects in 27 patients (29.3 %), aspiration syndrome in 25 patients (27.1 %), immune disorder in nine patients (9.7 %), pulmonary anomalies in two patients (2.1 %), and anhidrotic ectodermal dysplasia in one patient (1 %). CONCLUSIONS: Recurrent pneumonia occurred in 6.4 % of all children hospitalized for pneumonia. The underlying cause was identified in 86.7 % of the children. The most common causes were asthma, congenital cardiac defects, and aspiration syndrome.

Age Factors↗
PubMed1979

Lectin teratogenesis: defects produced by concanavalin A in fetal rabbits.

Concanavalin A (con A) is teratogenic to rabbit embryos during gestational days 12--15. Intracoelomic injections of 40 microliter con A solution (4 microgram/microliter) were performed on rabbit embryos during gestational days 10--15. Control embryos received either 40 microliter of saline, sham injection or no treatment. Con A caused increased fetal resorptions on days 10 and 11, but malformation levels did not differ from controls. On days 12--15, con A produced craniofacial, trunk and limb anomalies. The highest percentage of malformation occurred on day 14. The defects were classified into four groups: (1) malformations of limbs including paw and digital dysplasias as well as fusions of the limbs to the head or body wall; (2) "closure" defects such as umbilical hernia, encephalocoele, exencephaly or ectopia cordis; (3) "contracture" defects such as club paws, extended knees, or clenched digits, which exhibited normal osseous and cartilaginous skeletons; and (4) miscellaneous, non-specific anomalies including fused or dysplastic sternebrae or ribs. Histologic analysis of selected 12-day embryos 4 to 18 hours post-injection was performed to ascertain potential sites of teratogenic action. At 12 hours ectodermal necrosis was observed in the limb buds adjacent to the apical ectodermal ridge. By 18 hours, the ectoderm had eroded, exposing the basal lamina to the amniotic fluid. Focal areas of mesenchymal necrosis were observed in association with the ectodermal erosion. The potential roles of amniocentesis and limb bud repair in the genesis of the malformations are discussed.

Abnormalities, Drug-Induced↗
PubMed1984

Avian scale development. XI. Initial appearance of the dermal defect in scaleless skin.

The chicken mutant, scaleless, is characterized by the total absence of scutate scales. Previous experiments have shown that the scaleless defect is expressed by the epidermal cells while the dermal cells are able to participate in normal scale morphogenesis. However, in association with 14- to 16-day scaleless dermis, normal epidermis or the simple ectoderm of the chorion failed to develop scutate scale epidermis with its characteristic beta stratum. Thus the question arises: since the scaleless dermis starts out functioning normally, when does it become defective? Heterogenetic, heterotopic associations have been performed between 7.5-day to 11.5-day scaleless dermis and a neutral responding tissue, the midventral apteric epidermis, from 10.5-day normal embryos. The results show that up until 9.5 day of incubation the scaleless dermis is able to give instructions for normal scutate scale formation, if combined with normal epidermis. However, after 9.5 days, the scaleless dermis is not able to induce scale formation in normal apteric epidermis. Thus, the functional defect of the scaleless dermis occurs during the time (9 to 10 days of incubation) when epidermal placodes appear in normal embryos. From the present data, at least two explanations are possible. Either the scaleless epidermis is unable to respond to the placode inducing properties being provided by the scaleless dermis and because an epidermal placode does not form the scaleless dermis becomes defective, or the scaleless epidermis does not provide some earlier cue necessary for the scaleless dermis to acquire its placode inducing capabilities.

Animals↗
PubMed1987

Choanal atresia and athelia: methimazole teratogenicity or a new syndrome?

An infant girl with choanal atresia, athelia, minor anomalies, and mild to moderate mental retardation was born to a woman treated for hyperthyroidism throughout pregnancy with methimazole and propranolol. The patient's defects may be due to methimazole teratogenicity or could represent a previously undescribed syndrome affecting ectodermal structures.

Abnormalities, Drug-Induced↗
PubMed2006

The expanding panorama of split hand foot malformation.

The split hand/foot malformation is a developmental defect of the extremities resulting from errors in the initiation and maintenance of the apical ectodermal ridge. The phenotype is genetically heterogeneous, and it can be identified either as an isolated phenotypic manifestation or as a constituent component of a malformation syndrome. This overview describes the clinical phenotype, related animal models, and the evolving genetic heterogeneity of the malformation.

Abnormalities, Multiple↗
PubMed2006

Ets transcription factors regulate AIRE gene promoter.

Autoimmune regulator (AIRE) directs the expression of self-antigens in thymus. Defects in AIRE gene cause an organ-specific autoimmune disease called autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED). AIRE protein is mainly expressed in thymic medullary epithelial cells, thus implying a strict control over its expression pattern. To date, only limited information is available on mechanisms responsible for the regulation of AIRE gene. Here, we show that Ets transcription factor family members Ets-1, Ets-2, and ESE-1 have positive effect on AIRE transcription. Site-directed mutagenesis and transfection studies revealed that two of the three Ets binding sites in AIRE promoter are functional and this finding has been confirmed by the electrophoretic mobility shift assay. The AIRE promoter activity could be stimulated by phorbol myristate acetate (PMA) and this activation was further enhanced by Ets transcription factors. Our results demonstrate for the first time that AIRE gene is a downstream target for the Ets family of transcription factors.

Base Sequence↗