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Biomedical subjects

W J Gardner

Publications and source records attributed to W J Gardner.

At least 19 recordsLinked to original sources
PubMed1982

Aicardi's syndrome: a result of overdistention of the neural tube. The absent pineal gland.

The clinical picture of the Aicardi syndrome consists of a mentally retarded female infant with seizures, who lacks a corpus callosum and a pineal gland. There is Dandy-Walker malformation, vertebral anomalies, chorioretinopathy, coloboma, and heterotopia of gray matter. Since overdistention of the neural tube is the cause of each of these anatomic features, the same cause is responsible for the complete syndrome.

Agenesis of Corpus Callosum↗
PubMed1981

Overdistention of the neural tube causes congenital heart disease.

Congenital heart disease consists of cardiac anomalies that originated before or during the truncus arteriosus stage. The central nervous system, serving all organs, is the first to develop. It is the only organ possessing a third circulation. Immediately after the neural tube closes at the fourth week, its lining of immature ependymal cells secretes a proteinaceous neural tube fluid (NTF) at a pressure higher than the amniotic pressure. The resulting distention helps to shape not only the embryonic brain and spinal cord but also the bordering mesodermal cells that later will form vertebrae. The choroid plexus does not begin to secrete true cerebrospinal fluid until two weeks later. Should hypersecretion occur during this critical two week interval, the neural tube will overdistend and allow NTF to infiltrate into mesoderm (Fig. 1). Here, this fluid with its extraneous protein, may damage cells that are destined to form the anlagen of mesodermal organs such as the heart. It may also damage the primitive gut resulting in pulmonary, gastrointestinal and genitourinary anomalies. The most convincing evidence that the neural tube had been overdistended is the combination of anterior and posterior spina bifida that constitutes bilateral hemivertebrae. Vertebral anomalies are present in congenital heart disease though scarcely recognizable on the chest film of the newborn.

Animals↗
PubMed1980

Hypothesis; overdistention of the neural tube may cause anomalies of non-neural organs.

This hypothesis is offered by a neurological surgeon interested in anomalies of the central nervous system. It is based on accumulating evidence indicating that some neural tube defects result not from failure of the tube to close but from its rupture after closure. The central nervous system, serving all organs, is the first to develop and its maldevelopment may cause damage to other emerging structures. The neural tube closes during the fourth week and is immediately distended by a proteinaceous neural tube fluid (NTF) secreted by its lining cells at a pressure four to five times that of the surrounding amniotic fluid. This NTF has been miscalled "cerebrospinal fluid." The choroid plexus does not begin to secrete true cerebrospinal fluid (CSF) until 2 weeks later. If oversecretion of NTF should occur during this 2-week interval, the resulting overexpansion of the neural tube may spread apart the developing somite, eventuating in a combination of anterior and posterior spina bifida that constitutes bilateral hemivertebrae. If the distending neural tube ruptures beneath intact cutaneous ectoderm, the escaping NTF will infiltrate mesoderm. The resulting dislocation of cells and their possible injury by the extraneous protein may damage the as yet unidentifiable anlagen of mesodermal organs. If neural tube overdistention splits the underlying notochord and damages primitive gut, anomalies of entodermal organs may result. The neuroenteric cyst is one such anomaly that the neurosurgeon is called upon to treat. He finds it accompanied by hemivertebrae and hydromyelia. A preliminary report on this hypothesis has been published (Gardner and Breuer, '80).

Central Nervous System↗
PubMed1980

Anomalies of heart, spleen, kidneys, gut, and limbs may result from an overdistended neural tube: a hypothesis.

A hypothesis is advanced that many congenital anomalies of non-neural organs may be produced by damage to their mesodermal or entodermal anlagen caused by overdistention of the embryonic neural tube. Evidence to support the hypothesis derives from: (1) seldom appreciated but unequivocal embryologic facts about prechoroid plexus neural tube morphogenesis; (2) an understanding of the role of neural tube overdistention in the production of various dysraphic conditions; (3) the frequency of association of non-neural anomalies with dysraphic conditions; and 4) an analysis of the anatomic features of the organ anomalies associated with dysraphism. The practical utility of the hypothesis is that (1) it helps explain a seemingly widely divergent subset of phenomenology and (2) it is testable. At present, treatment of children with congenital anomalies is largely palliative. Prevention of these distressing defects in the future will only be realizable if the mechanisms of their genesis are more clearly understood.

Abnormalities, Multiple↗
PubMed1979

Isolation and characterisation of guanine auxotrophs in Saccharomyces cerevisiae.

Mutants of yeast which are auxotrophic for guanine have been isolated from two prototrophic haploid strains, one of which carried the suppressor of purine excretion, su-pur, and the other carried the alternative allele, su-pur+. The mutants were allocated to three genes, gual, gua2, and gua3, between which no close linkage was demonstrable. Mutants of all three genes were recessive and showed normal Mendelian segregation in crosses. The gene gual was shown by an in vivo enzyme assay procedure to specify guanosine 5'-phosphate (GMP) synthetase, the second enzyme involved in the biosynthesis of GMP from inosine 5'-phosphate (IMP). Mutants of this gene excrete large amounts of purine derivatives, predominantly xanthosine, into guanine-free, but not into guanine-supplemented, medium. The gene gau2 is probably involved in the biosynthesis of riboflavin from guanine nucleotides; the phenotype of these mutants suggests a possible interaction between aromatic amino acid metabolism and riboflavin biosynthesis. No role for gua3 can be assigned on the evidence so far available, but it is not involved in the specification of IMP dehydrogenase, the first enzyme involved in the synthesis of GMP and IMP.

Cell-Free System↗
PubMed1979

Klippel-Feil syndrome, iniencephalus, anencephalus, hindbrain hernia and mirror movements: overdistention of the neural tube.

Bony anomalies encountered in the 'no neck' form of Klippel-Feil syndrome (KFS) are a wide, short, fused, bifid, retroflexed spinal canal; craniolacunia, cranium bifidum, and acrania. The only symptom may be mirror movement (MM). The CNS anomalies are hindbrain hernia, hydrocephalus, hydromyelia, syringomyelia, meningocele, myelocele, encephalocele, and anencephalus. In severe KFS, i.e. iniencephalus (IN) and in anencephalus (AN), the inion is in contact with the back. In both there is hindbrain hernia and the left thorax may contain the stomach tethered to an anterior spina bifida. KFS results from distortion of somites by an overdistended neural tube. A neural tube that fails to close cannot overdistend.

Adolescent↗
PubMed1977

Hydrodynamic factors in Dandy-Walker and Arnold-Chiari malformations.

The Dandy-Walker malformation (DWM) is hydrocephalus that primarily affects the fourth ventricle, whose overdistention involves also the aqueduct and third ventricle. However, just the opposite is true in the Arnold-Chiari malformation (ACM) since the hydrocephalus is limited to the lateral ventricles which squeeze the third ventricle between them and compress the aqueduct and fourth ventricle. The evidence indicates that both result from hydrodynamic stresses in embryonal and early fetal life. This communication is offered in rebuttal to some statements in an otherwise authoritative and comprehensive article.

Arnold-Chiari Malformation↗
PubMed1977

Terminal ventriculostomy for syringomyelia.

The clinical course of 12 patients who underwent terminal ventriculostomy for syringomyelia is presented. Opening the central canal at the tip of the conus medullaris is a relatively benign procedure that improves the symptoms of syringomyelia and syringobulbia. This canal normally terminates at the tip of the conus, but in each of the 12 surgical specimens it continued into the filum terminale for distances up to 8 cm. In most cases the tip of the conus was located more caudally than normal, indicating some degree of tethering in fetal life. This belief is supported by the fact that the newborn, whose conus is tethered to a lipoma at the sacral level, may develop syringomyelia in adult life.

Adult↗
PubMed1977

Syringomyelia.

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Humans↗