Cause Of Abnormal Development Research Articles

DEVELOPMENTAL HIP DYSPLASIA AND DISLOCATION

A thorough knowledge of the normal growth and development of the hip, the causes of abnormal development, and the structural and functional changes that result from developmental hip dysplasia and dislocation provide needed information for treating these conditions. Ultrasonography, newborn screening, and radiographic evaluation are important diagnostic tools.

Developmental Consequences of Trace Mineral Deficiencies in Rodents: Acute and Long-Term Effects

Approximately 3% of infants born have at least one serious congenital malformation. In the U.S., an average of 10 infants per thousand die before 1 y of life; about half of these deaths can be attributed to birth defects, low birth weight or prematurity. Although the causes of developmental abnormalities are clearly multifactorial in nature, we suggest that a common factor contributing to the occurrence of developmental abnormalities is suboptimal mineral nutrition during embryonic and fetal development. Using zinc and copper as examples, evidence is presented that nutritional deficiencies can rapidly affect the developing conceptus and result in gross structural abnormalities. Deficits of zinc or copper can result in rapid changes in cellular redox balance, tissue oxidative stress, inappropriate patterns of cell death, alterations in the migration of neural crest cells and changes in the expression of key patterning genes. In addition to well-recognized malformations, mineral deficiencies during perinatal development can result in behavioral, immunological and biochemical abnormalities that persist into adulthood. Although these persistent defects can in part be attributed to subtle morphological abnormalities, in other cases they may be secondary to epigenetic or developmental changes in DNA methylation patterns. Epigenetic defects combined with subtle morphological abnormalities can influence an individual's risk for certain chronic diseases and thus influence his or her risk for morbidity and mortality later in life.

Diploid-dependent regulation of gene expression: a genetic cause of abnormal development in fish haploid embryos.

A diploid-dependent regulatory mechanism of gene expression for spatial patterning of the eye in vertebrates has been determined by analyzing the phenotypes of haploid goldfish embryos. There are two gene loci in charge of eye spatial patterning during embryonic morphogenesis. The expressional probability for each copy of the two genes in a set of chromosomes is 50%. A pair of genes in two sets of homologous or heterologous chromosomes is 100% and essential for normal gene expression. The haploid condition itself would result in the obstruction of gene expression and abnormal development because the diploid-dependent regulatory apparatus will regulate gene expression in a haploid embryo according to the same rule as in the diploid embryo.

Lung growth for beginners

Lung growth occurs as a series of tightly regulated events commencing in the embryo and continuing post-natally. It depends on a number of factors, including developmental, genetic and environment ones. Abnormalities of any of these factors may have a profound influence on lung growth. The causes of developmental abnormalities of the lung such as lung cysts and congenital diaphragmatic hernia are poorly understood, but may result from a combination of genetic and environmental factors. Normal fetal breathing movements and an adequate balance between the production of fetal lung fluid and drainage of this fluid are both essential for normal fetal lung growth. It seems that fetal breathing movements are necessary to maintain sufficient pressure within the airways and perhaps to directly stimulate lung growth via induction of mitogenic activity. The volume of intra-pulmonary fluid is regulated by the resistance of the upper airway and by contractions of the diaphragm. Increased drainage of the amniotic fluid, another essential factor for normal lung growth and development, will result in marked pulmonary hypoplasia as may occur with pre-term rupture of the membranes and with fetal renal disease. Perhaps the most important factor for adverse lung growth is pre-term delivery of the infant from any cause including intra-uterine infection. Both ante- and post-natal factors, including mechanical ventilation and oxygen therapy, will affect normal alveolization. In this review, particular attention is paid to breathing movements and the balance between fluid production and drainage.

A Case of Unique Communication Between Blind-Ending Ectopic Ureter and Ipsilateral Hemi-Hematocolpometra in Uterus Didelphys

Uterus didelphys with double vagina and hemi-vaginal atresia is a rare syndrome of congenital anomalies. A 17-year-old girl had a right blind-ending ectopic ureter, the proximal end of which communicated with the ipsilateral uterine cervix of uterus didelphys. The patient presented with vaginal urinary incontinence after incision of the vaginal wall for right hemi-hematocolpometra. Following various examinations, the ipsilateral kidney was found to be absent. The ectopic ureter and communicating duct were resected, and the fistula was closed. The genesis of malformation of the female genitalia and urinary tract resulting in such a unique communication is discussed. The importance of preoperative meticulous examinations, including cysto-genitography, pelvic magnetic resonance imaging and panendoscopy with the patient under anesthesia, is emphasized.

Developmental Facial Abnormalities and the Temporomandibular Joint

The mandibular condyle, an integral part of the temporomandibular joint, contains an important endochrondral epiphyseal-like growth site. Prenatal or postnatal and local or systemic conditions, which either stimulate or depress the activity of this zone, may cause over- or underdevelopment of the mandible and related structures. The degree of the subsequent deformity will depend not only on the type, intensity, extent, and chronology of the noxious agent, but also on the particular susceptibility and growth activity of the site. In addition, factors influencing apposition and resorption of bone further modify the growth pattern of the temporomandibular joint and face. Although some facial abnormalities reflect primarily alterations in growth of the mandibular condyle, there are others in which changes in the condyle are secondary and only part of a larger involvement of the ear, the face, and sometimes other parts of the body. Much has been learned about the etiology of facial and other abnormalities in the experimental animal. As yet, considerably less is known about the causes of developmental abnormalities in man. It is important to remember, moreover, that what applies to lower animals does not necessarily apply to humans. Within the last decade conditions which were believed to be on a hereditary basis are now known to be the result of changes in the fetal environment. Teratology, an exciting, fascinating, and rapidly developing field of study, has much to offer. Another interesting factor to consider is the effect of our external environment, such as variations in gravity, on the size and shape of our temporomandibular joints, jaws, face, and body. On Earth, gravity is considered normal or 1G. What skeletal and other changes will occur in environments of hypogravity (Moon, 0.18G) or hypergravity (Jupiter 2.65G)? As yet, relatively little is known.

Experimental causation of congenital skeletal defects and its significance in orthopaedic surgery.

Experimental causation of congenital skeletal defects and its significance in orthopaedic surgery.

THE CONDITIONS THAT LEAD TO NORMAL OR ABNORMAL DEVELOPMENT OF CIONA

Eggs of Ciona that develop in covered Syracuse dishes produce as a rule normal tadpoles in the course of 24 hours, but occasionally only abnormal embryos develop, or both normal and abnormal in the same dish. Reciprocal crosses sometimes give very different proportions of normals and abnormals, but the relations are often very inconsistent. The results cannot be ascribed to the eggs alone or to the sperm or to their combinations. Even if an attempt is made to refer the outcome of the reciprocal crosses to the cytoplasm of the egg, that has developed under the influence of the diploid nucleus of the egg, still the differences cannot be satisfactorily accounted for. Polyspermy can account for only a very small percentage of abnormal development, probably not more than half of one per cent. Delay in fertilizing the eggs does not cause abnormal development. Delay in using the sperm suspension does not cause abnormals. When the eggs of one individual are fertilized by the same amount of sperm suspension of six other individuals, the outcome may be normals in each dish or normals and abnormals, or occasionally, all are abnormals. When the sperm of one individual is used to fertilize the eggs of six others, the same kind of results may happen. In order to make the samples of eggs as nearly alike as possible, they were first fertilized in a large volume of water, and, when in the two-cell stage, a few were transferred to several small Syracuse dishes. The same kind of irregularities appeared, which cannot be due to chance selection of different eggs, for the original eggs left in the large amount of water generally gave more than 95 per cent normals. Therefore, several kinds of experiments were made to find out whether differences in the small dishes will account for the occasional, but persistent, appearance of abnormals. (1) Dirt or impurities in the sea water from the tap was excluded. (2) Evaporation of the sea water in the covered Syracuse dishes was not enough to cause abnormal development. (3) Ordinary washing of the dishes, even rinsing them in distilled water did not remove the cause of abnormal development in some of the dishes. (4) But sterilizing the dishes in an autoclave removed the cause of most of the irregularities. It follows that the cause of the exceptional cases of abnormals is due to some contamination that remains in the dishes after washing them in fresh tap water. Since the contamination does not affect the early development of eggs (cleavage), but only later stages, it must be putrefactive in origin; and since it is removed by autoclaving the dishes, it is probably bacterial or some sort of organic contamination. The eggs come to rest on the bottom of the dishes in a few minutes where they remain until the tadpole emerges, hence local differences may affect the development and account for those cases where both normal and abnormal development takes place in the same dish. The discovery of the cause of the occasional abnormal development removes the possibility that it is due to genetic factors, hence is not concerned with the self-sterility of Ciona.