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Multiple roles for Hedgehog signaling in zebrafish pituitary development.

The endocrine-secreting lobe of the pituitary gland, or adenohypophysis, forms from cells at the anterior margin of the neural plate through inductive interactions involving secreted morphogens of the Hedgehog (Hh), fibroblast growth factor (FGF), and bone morphogenetic protein (BMP) families. To better understand when and where Hh signaling influences pituitary development, we have analyzed the effects of blocking Hh signaling both pharmacologically (cyclopamine treatments) and genetically (zebrafish Hh pathway mutants). While current models state that Shh signaling from the oral ectoderm patterns the pituitary after placode induction, our data suggest that Shh plays a direct early role in both pituitary induction and patterning, and that early Hh signals comes from adjacent neural ectoderm. We report that Hh signaling is necessary between 10 and 15 h of development for induction of the zebrafish adenohypophysis, a time when shh is expressed only in neural tissue. We show that the Hh responsive genes ptc1 and nk2.2 are expressed in preplacodal cells at the anterior margin of the neural tube at this time, indicating that these cells are directly receiving Hh signals. Later (15-20 h) cyclopamine treatments disrupt anterior expression of nk2.2 and Prolactin, showing that early functional patterning requires Hh signals. Consistent with a direct role for Hh signaling in pituitary induction and patterning, overexpression of Shh results in expanded adenohypophyseal expression of lim3, expansion of nk2.2 into the posterior adenohypophysis, and an increase in Prolactin- and Somatolactin-secreting cells. We also use the zebrafish Hh pathway mutants to document the range of pituitary defects that occur when different elements of the Hh signaling pathway are mutated. These defects, ranging from a complete loss of the adenohypophysis (smu/smo and yot/gli2 mutants) to more subtle patterning defects (dtr/gli1 mutants), may correlate to human Hh signaling mutant phenotypes seen in Holoprosencephaly and other congenital disorders. Our results reveal multiple and distinct roles for Hh signaling in the formation of the vertebrate pituitary gland, and suggest that Hh signaling from neural ectoderm is necessary for induction and functional patterning of the vertebrate pituitary gland.

Animals↗

The "stright-jacket" syndrome in chicks. II. Mechanism of development.

In a longitudinal study including measurement of the pressure in the amniotic cavity, amniotomy, and planimetric evaluation of the size of the amniotic sac, we investigated the development of the "strait jacket" syndrome in White Leghorn chicken embryos injected intraamniotically (ia) or paraamniotically on the fourth day of incubation with histone or embryotoxic serum, with the following results. Hyperlordosis and eventration developed as an outcome of tonic contraction of the amnion, which was observed only three hours after ia administration. Contraction of the amnion caused elevation of the intraamniotic pressure, which, 12 hours after ia injection, attained a mean value of 22.4 Pa (2.3 mm H2O). This value was not only significantly higher than the mean for control embryos (3.9 Pa), but it was critically close to the mean fluid pressure in the brain vesicles. Loss of the latter overpressure caused the vesicles to collapse, and the walls shriveled and exencephaly developed. Paraamniotic injection was not followed by either contraction of the amnion, or significant increase in intraamniotic pressure. This did not prevent heart malformations and cranioschisis of various extent. The majority of cardiovascular malformations were probably the hemodynamic consequence of overfilling of the intraembryonic vascular bed, which was one of the early signs of the effect question. Cranial-vault defects can be causally associated with the formation of amnionic adhesion and fusion with the epidermal ectoderm. This observation stresses the significance of the embryonic membranes and the fluid pressures within them for the development of certain congenital deformities and concentrates attention on teratological study of substances that induce protracted contraction of smooth muscle.

Abnormalities, Drug-Induced↗

Perioperative care of the child with the Johanson-Blizzard syndrome.

The Johanson-Blizzard Syndrome (JBS) is an autosomal recessive disorder with a characteristic phenotype, including dwarfism, a beaked nose with aplastic alae nasi, a high forehead, mid-line ectodermal scalp defects with sparse hair and absent eyelashes/eyebrows, prominent scalp veins, low set ears, a large anterior fontanelle, micrognathia, thin lips, absent permanent dentition and microcephaly. In addition to the characteristic facial features, associated conditions include congenital heart disease, exocrine/endocrine pancreatic dysfunction, hypothyroidism, hypopituitarism, mental retardation, sensorineural hearing loss and vesico-ureteral reflux. A case is presented and the potential anaesthetic implications of this syndrome are discussed.

Abnormalities, Multiple↗

[Congenital hand malformation--local disturbance in the limb bud and longitudinal deficiency: an experimental study on the pathogenesis].

Experimental congenital malformation produced in fetal chickens to investigate any correlation between a local disturbance in the limb buds and longitudinal deficiency, and to elucidate the pathogenesis of radial and ulnar ray deficiencies. Fertilized White Leghorn eggs were incubated at 38.0 degrees C and windowed. The right wing bud of the embryos was locally cauterized using a bipolar microcoagulator under a microscope. Cauterization was carried out from 2.5 days to 5.5 days of development, at 12-hour intervals. Each wing bud was divided into 6 areas: axial (distal and proximal), preaxial (distal and proximal) and postaxial (distal and proximal). After cauterization the eggs were sealed with micropore tape and further incubated until the 21st-23rd day. The chick wings were then removed and investigated macroscopically and roentgenographically. The wing buds had been examined microscopically after cauterization on the 3rd day until ray deficiencies were produced on the 5th day. Radial ray deficiencies were produced by cauterization in the distal preaxial area, and ulnar ray deficiencies by cauterization in the distal postaxial area. These results indicated a peculiarity of the longitudinal axis. However, the critical periods of the radial and the ulnar ray deficiencies were the same; from immediately after the formation of the wing bud to before the formation of the digital plate. The patterns of the combined defects in the digits and of other associated deformities were quite similar to those found in human malformations. Microscopically necrosis in the mesoderm and in the overlying ectoderm of the pre and postaxial areas of the tip of a wing bud caused defects in the cartilaginous primordium in the same ray.

Animals↗

Ocular manifestations in a father and son with EEC syndrome.

BACKGROUND: The ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome is a rare disease which follows an autosomal-dominant pattern of inheritance. Due to the ectodermal dysplasia there is atresia of the lacrimal duct system and aplasia of the meibomian glands with a defective tear film. Therefore, vascularized corneal scars often form during early adult life. PATIENTS: Father aged 41 years, and son aged 23 months. Both patients: stenosis/atresia of lacrimal duct systems (the father had twice undergone dacryocystorhinostomy externally) with epiphora, lip-palate clefting, syndactylies of fingers and toes, lobster deformities of hands. Additional ophthalmological findings in the father: bilaterally extracted juvenile cataracts with implantation of intraocular lenses, bilateral extensive vascularized corneal scars. Additional dermatological findings in the father: malignant melanoma of the calf, now in complete remission following several operations on the melanoma and several cycles of chemotherapy for the metastases. DISCUSSION AND THERAPEUTIC CONCLUSIONS: Father and son show the full clinical picture of the EEC syndrome with clefting, lobster-like deformities of the hands and ectodermal dysplasia with tear duct atresia and aplasia of the meibomian glands with defective tear film. During childhood, the main handicapping features are the clefting and the hand deformities with their respective multiple operative revisions. During early adulthood, however, the ocular problems become the predominantly handicapping aspects of the EEC syndrome; due to the ectodermal dysplasia, vascularized corneal scarring develops. Tearing and secondary inflammation due to lacrimal duct atresia has to be treated by early dacryocystorhinostomy. As secondary infections promote the development of corneal scars, one should not postpone the operation too long. Infections have to be treated promptly by local antibiotics. Because of the aplasia of the meibomian glands, artificial tear substitution should be given on a regular basis to support the defective tear film. Thus, the development of vascularized corneal scars can perhaps be delayed. Once corneal scarring has developed, perforating keratoplasty has a poor prognosis due to the ectodermal dysplasia, the absence of the meibomian glands and the defective tear film. Three factors lead to the formation of vascularized corneal scars: recurrent infections of lid margins and conjunctiva due to obstructed tear ducts; defective tear film with insufficient lipid phase due to the aplasia of the meibomian glands; and primary corneal epithelial defects in the course of the generalized ectodermal dysplasia.

Adult↗

Rapp-Hodgkin syndrome with palmoplantar keratoderma, glossy tongue, congenital absence of lingual frenum and of sublingual caruncles: newly recognized findings.

We report on a boy with Rapp-Hodgkin syndrome (RHS) or Rapp-Hodgkin ectodermal dysplasia. He had sparse, wiry, slow growing and uncombable hair, but no pili torti or pili canaliculi characteristic of RHS. He also had sparse eyelashes and eyebrows, and obstructed lacrimal puncta and epiphora. Bilateral bony external auditory canal stenosis led to hearing loss. The mouth was small with repaired bilateral cleft lip and palate. Oral manifestations included hypodontia, microdontia, unerupted mandibular premolars with well formed roots, large dental pulp spaces, enamel hypoplasia, multiple caries, glossy tongue, and congenital absence of lingual frenum and of sublingual caruncles including submandibular and sublingual salivary duct openings. Palmo-plantar keratoderma, unerupted premolars, congenital absence of lingual frenum, sublingual caruncles, glossy tongue, and pili canaliculi seen in the patient are newly recognized findings of this syndrome. Overlapping findings of RHS ectrodactyly-ectodermal dysplasia-clefting syndrome (EEC), and ankyloblepharon-ectodermal defects-cleft lip and palate syndrome (AEC) are discussed.

Carbuncle↗

Short limbed dwarfism, genital hypoplasia, sparse hair, and vertebral anomalies: a variant of Ellis-van Creveld syndrome?

A male newborn with acromesomelic short limbed dwarfism, genital hypoplasia, and vertebral anomalies is reported. As the child had an important number of clinical and radiological symptoms seen in patients with Ellis-van Creveld syndrome, we raise the question of whether he may represent a variant example of this syndrome despite the absence of cardinal symptoms such as postaxial polydactyly and ectodermal changes (nail hypoplasia).

Abnormalities, Multiple↗

Clinical and epidemiological findings in patients with central ray deficiency: split hand foot malformation (SHFM) in Manitoba, Canada.

We conducted a clinical population study to examine the incidence and epidemiology of split hand foot-malformation (SHFM) in Manitoba from 1957 to 2003. The total number of births during this period was 850,742. Forty-three patients with SHFM were identified, resulting in an incidence of 1 in 19,784 births. Most patients were ascertained through referrals to the Section of Genetics and Metabolism at the Children's Hospital, Winnipeg, Manitoba. Overall, 22 (51.2%) of affected individuals were females and 21 (48.8%) were male. The left upper limb (LUL) was the most frequently affected, (in 46.5% of patients). The right hand was involved in 39.5%. In 4 patients (9.3%) all four limbs were affected. SHFM is classified as a failure of formation of parts according to the International Federation of Surgical Societies of the Hand (IFSSH) and has also been categorized as Typical or Atypical. Individuals in the Manitoba cohort were classified into two main categories: Typical (29 cases) and Atypical (3 cases). However, 11 patients were not easily placed into either group and comprised a distinct category termed "difficult to classify." Patients in the three groups were then further subdivided depending on whether or not they had additional congenital anomalies. These complex patients included those with single gene disorders in which SHFM has been reported (e.g., ectodermal dysplasia Ectrodactyly Clefting (EEC), tibial aplasia with SHFM, fibular aplasia with SHFM), as well as those with other recognized or unknown patterns of anomalies. Two had deletions involving 9q and 5p respectively. Unlike some other studies, we did not find an excess of males or right-sided defects and only two of the cases--two sisters--were related.

Cohort Studies↗

Histological changes induced in developing limb buds of C57BL mouse embryos submitted in utero to the combined influence of acetazolamide and cadmium sulphate.

Microscopic defects in limb buds of C57BL mouse embryos after the combined teratogenic action of acetazolamide plus cadmium sulphate administered on day 9 of gestation were studied in serial sections. Postaxial deficiencies observed in 12-15-day embryos and affecting preferentially the right forelimbs were classified in nine morphological types according to increasing amounts of missing parts. Type X defect consists of a nearly complete amelia in which all four limbs are represented only by the girdle and proximal end of the stylopod. Type XI abnormality appears as an intermediate reduction affecting the area of digit IV. In addition to modifications of the forelimb bud shape detected from the 10-day stage onwards, observations made 24 and 48 hr after treatment confirmed that the postaxial defects result from an absolute lack of postaxial mesoderm occurring without cell necrosis as a consequence of a postaxial shortening of the apical ectodermal ridge (aer). In 10-day embryos, the latter appears shortened and hypertrophied; it is later fragmented into alternate thick and thin portions in 11-day affected limb buds. These ectodermal changes might account for the genesis of all types of defects observed. Untreated 9-day embryos with 12-25 pairs of somites display a number of asymmetries between their right and left forelimb territories: Until the 19-somite stage, the vascular supply to that area is provided exclusively by the umbilical vein, which is larger on the right side; the initial amount of somatopleural limb mesoderm is greater in the right rudiment and the genesis of its aer is slightly protracted as compared to the left one. These asymmetries might contribute to the right side predominance of the forelimb defects induced by acetazolamide and cadmium.

Abnormalities, Drug-Induced↗

Familial ichthyosis, dwarfism, mental retardation, and renal disease.

The nonrandom association of congenital ichthyosis with neurologic impairment, ectodermal dysplasia, dwarfism, hypogonadism, and renal disease has prompted the review of numerous syndromes. The difficulties in characterization of syndromes in the absence of pathognomonic signs is discussed in relation to three siblings presented herein. Despite extensive investigation, underlying metabolic defects remain obscure.

Adult↗

[Pili torti et canaliculi in ectodermal dysplasia].

Uncombable hair is a heterogeneous symptom with a partially genetic background. In order to make an exact diagnosis, it is mandatory to recognize associated abnormalities, do pedigree analyses, and perform scanning electron microscopic studies of the hair. In a case of ectodermal dysplasia, ectrodactyly, cleft lip/palate (EEC) syndrome and in a patient with familial tricho-odonto-onychial ectodermal dysplasia with syndactyly, scanning electron microscopy demonstrated pili torti et canaliculi, helicotrichia and cuticular dystrophy. Congenital pili torti et canaliculi must be differentiated from pili torti and from pili trianguli et canaliculi ("cheveux incoiffables"), inasmuch as they may present in hypotrichosis congenita hereditaria of Marie-Unna or as part of complex ectodermal dysplasia syndromes with clefting of the lip/palate and/or limb defects. It is noteworthy that some of those patients show a dysmorphic facies and an atopic constitution in addition to the aforementioned abnormalities. We discuss the possible relationship of these syndromes to each other, with special respect to the Hay-Wells or ankyloblepharon, ectodermal dysplasia, cleft lip/palate (AEC) and the Rapp-Hodgkin (ectodermal dysplasia, midfacial hypoplasia, cleft lip/palate) syndromes.

Abnormalities, Multiple↗

Handless, footless fetus.

We report a fetus with symmetrical terminal transverse limb deficiency. Two earlier reports described patients with similar defects. These patients resemble the animal models that result from the removal of apical ectodermal ridge.

Abnormalities, Multiple↗

Aplasia cutis congenita. Case report.

The authors report the use of intraoperative tissue expansion in the treatment of a neonate with aplasia cutis congenita, a congenital defect of the scalp and skull. The case for immediate surgical intervention is presented, and intraoperative tissue expansion and cranioplasty are recommended as components of an effective surgical approach.

Adult↗

Are cardio-facio-cutaneous syndrome and Noonan syndrome distinct? A case of CFC offspring of a mother with Noonan syndrome.

Cardio-facio-cutaneous syndrome is characterized by complex congenital heart disease, characteristic facies, ectodermal abnormalities, growth failure, and mental retardation. It has been described as a distinctive entity from Noonan syndrome. This paper presents a child with cardio-facio-cutaneous syndrome born to a mother with Noonan syndrome. This is suggestive of cardio-facio-cutaneous syndrome being a variable expression of Noonan syndrome.

Adult↗