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Biomedical subjects

E Pera

Publications and source records attributed to E Pera.

8 recordsLinked to original sources
PubMed2001

Molecular mechanisms of cell-cell signaling by the Spemann-Mangold organizer.

We review how studies on the first Spemann-Mangold organizer marker, the homeobox gene goosecoid, led to the discovery of secreted factors that pattern the vertebrate embryo. Microinjection of goosecoid mRNA formed secondary axes and recruited neighboring cells. These non-cell autonomous effects are mediated in part by the expression of secreted factors such as chordin, cerberus and Frzb-1. Unexpectedly, many of the molecules secreted by the Spemann-Mangold organizer turned out to be antagonists that bind growth factors in the extracellular space and prevent them from binding to their receptors. The case of chordin is reviewed in detail, for this molecule has provided biochemical insights into how patterning by Spemann's organizer can be regulated by diffusion and proteolytic control. The study of the BMP-binding repeats of Chordin, which are present in many extracellular proteins, may provide a new paradigm for how cell-cell signaling is regulated in the extracellular space not only in embryos, but also in adult tissues.

Amino Acid Sequence↗
PubMed1999

Expression of DLX3 in chick embryos.

Higher vertebrates appear to possess six genes encoding a homeodomain of the distal-less type. We report the cloning and expression pattern of the chicken DLX3 gene, a homeobox gene highly related to the DLX5 gene with regard to both the encoded protein structure and the expression pattern. DLX3 RNA was observed during the development of the olfactory and otic placodes, in the distal portion of the first and second visceral arch mesenchyme, in the growing limb buds, and in the tail tip. No expression occurs in the central nervous system.

Amino Acid Sequence↗
PubMed1999

Ectodermal patterning in the avian embryo: epidermis versus neural plate.

Ectodermal patterning of the chick embryo begins in the uterus and continues during gastrulation, when cells with a neural fate become restricted to the neural plate around the primitive streak, and cells fated to become the epidermis to the periphery. The prospective epidermis at early stages is characterized by the expression of the homeobox gene DLX5, which remains an epidermal marker during gastrulation and neurulation. Later, some DLX5-expressing cells become internalized into the ventral forebrain and the neural crest at the hindbrain level. We studied the mechanism of ectodermal patterning by transplantation of Hensen's nodes and prechordal plates. The DLX5 marker indicates that not only a neural plate, but also a surrounding epidermis is induced in such operations. Similar effects can be obtained with neural plate grafts. These experiments demonstrate that the induction of a DLX5-positive epidermis is triggered by the midline, and the effect is transferred via the neural plate to the periphery. By repeated extirpations of the endoderm we suppressed the formation of an endoderm/mesoderm layer under the epiblast. This led to the generation of epidermis, and to the inhibition of neuroepithelium in the naked ectoderm. This suggests a signal necessary for neural, but inhibitory for epidermal development, normally coming from the lower layers. Finally, we demonstrate that BMP4, as well as BMP2, is capable of inducing epidermal fate by distorting the epidermis-neural plate boundary. This, however, does not happen independently within the neural plate or outside the normal DLX5 domain. In the area opaca, the co-transplantation of a BMP4 bead with a node graft leads to the induction of DLX5, thus indicating the cooperation of two factors. We conclude that ectodermal patterning is achieved by signalling both from the midline and from the periphery, within the upper but also from the lower layers.

Animals↗
PubMed1986

Prognostic factors in laryngeal carcinoma. A multifactorial study of 416 cases.

The prognostic significance of 20 clinical and histologic parameters was evaluated in a series of 416 laryngeal carcinomas treated between 1969 and 1981 at the Hospital de Santa Cruz y San Pablo, Barcelona, Spain. Clinical follow-up ranged from 2 to 13 years. The variables considered were: age, smoking habits, previous laryngeal disease, duration of clinical symptoms, motility of vocal cords, interval between diagnosis and treatment, postoperative infection, topographic location of the tumor, previous tracheostomy, ulceration, tumor size, resection margins, histologic grading, patterns of growth, types of invasion, mitotic index, depth of invasion, positive lymph nodes, T categories and N categories. Fourteen parameters were found to be significantly related to survival. After a multifactorial study using Cox's life table regression model, 5 of those 14 parameters were found to influence survival independently. The five variables ordered according to prognostic significance were: (1) positive lymph nodes, (2) T categories, (3) histologic grading, (4) ulceration, and (5) location.

Actuarial Analysis↗
PubMed1985

Rhinitis leprosary.

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Diagnosis, Differential↗