PubMed Health⌕ Search

Biomedical subjects

J G Hall

Publications and source records attributed to J G Hall.

At least 181 records · Page 10Linked to original sources
PubMed1986

Fetal mortality in sibships of cases with neural tube defects.

Rates of fetal mortality in sibships of probands with neural tube defects (NTDs) may reflect liability to NTDs. Expectations from the multifactorial model predict that fetal loss should be higher in sibships of male probands; in multiplex sibships; and sibships where the proband had no additional malformations. This was analysed for 715 pregnancies from 398 sibships. In general, the results did not support the expectations of the multifactorial model.

Abortion, Spontaneous↗
PubMed1986

Growth curves for height in Noonan syndrome.

Growth retardation is a relatively consistent feature of Noonan syndrome but a standardized growth curve for height has never been calculated. Analysis of retrospective growth data on 112 patients with Noonan syndrome has permitted the establishment of preliminary reference growth standards for height for males and females. The results confirm the clinical impression that short stature among this group of patients occurs uniformly and is independent of chronological age. Various factors which may modify this are considered.

Adolescent↗
PubMed1986

Sulphated polysaccharides, corticosteroids and lymphocyte recirculation.

Intermediate lymph was collected from the efferent duct of a single, superficial lymph node in unanaesthetised sheep for a few days before and after they were given an intravenous (i.v.) injection of a sulphated polysaccharide, fucoidan, at a dose of 10 mg per kg. Within an hour or so of the injection, the recirculation of lymphocytes through the node under study fell by over 80% and remained low for a few hours. This acute reduction in lymphocyte recirculation could be duplicated almost exactly by giving an i.v. dose (250 micrograms per kg) of a synthetic corticosteroid, dexamethasone, instead of fucoidan. Also, during the fall in lymphocyte recirculation that followed the injection of fucoidan, the concentration of cortisol in the blood plasma increased nearly 10-fold. These findings strongly suggest that much of the effect of exogenous sulphated polysaccharides on the recirculation of lymphocytes is neither direct nor specific, but secondary to an increased secretion of corticosteroid hormones.

Animals↗
PubMed1986

Obstetric and gynecologic problems in women with chondrodystrophies.

Despite the growing body of knowledge on the natural history of various chondrodystrophies, little is known of the associated obstetric and gynecologic problems. The authors have surveyed by questionnaire 150 women with chondrodystrophies after a request by the women of Little People of America and Little People of Canada that a survey of their members be carried out. It was found that some obstetric and gynecologic problems are common to all women with short stature. There is an increased incidence of menstrual complications, problems with certain methods of contraception, and evidence of reduced fertility. In addition, delivery should almost always be by cesarean section under general anesthesia. There are, however, some unique complications in specific chondrodystrophies in the present study group. Women with achondroplasia have premature menopause and an increased incidence of leiomyomata; women with osteogenesis imperfecta have late menarche; and women with pseudoachondroplasia and cartilage hair hypoplasia have long menstrual cycles.

Adolescent↗
PubMed1985

A differential effect of naloxone on transmission of impulses in primary afferents to ventral roots and ascending spinal tracts.

Ventral root reflexes and ascending volleys to stimulation of group I muscle afferents, large diameter cutaneous afferents and unmyelinated primary afferents were examined in barbiturate anaesthetized spinal cats. Intravenous naloxone (0.05-0.10 mg/kg) increased reflexes to stimulation of all primary afferent types but of the ascending volleys, only those to stimulation of unmyelinated primary afferents were increased. Thus it appears that opioid peptides have differential effects on transmission of primary afferent impulses to supraspinal areas, an action possibly relevant to analgesia, in contrast to a non-selective suppression of transmission to motoneurones.

Afferent Pathways↗
PubMed1985

Tuberous sclerosis: case report and investigation of family members.

Familial tuberous sclerosis probably occurs more often than is indicated by the literature: many family members show signs of being carriers of the gene for the disease when carefully examined. This article reports on a family with documented tuberous sclerosis in three generations and discusses the examination and investigation of at-risk family members, including the newborn, for signs of the disease. The potential teratogenic effects of anticonvulsants, used to control seizures in tuberous sclerosis, are also discussed.

Adult↗
PubMed1985

Oculocerebrocutaneous syndrome.

A female infant was found at birth to have an oculocerebrocutaneous syndrome in which the main clinical features include orbital cyst, cerebral malformations, accessory skin tags, and focal hypoplasia or "punched-out" skin lesions. This case, like the four previously reported, was sporadic.

Brain↗
PubMed1985

Noonan phenotype associated with neurofibromatosis.

We report on four patients with neurofibromatosis and manifestations of Noonan syndrome including short stature, ptosis, "midface hypoplasia," apparently short webbed neck, learning disabilities, and weakness. No family history of neurofibromatosis was present in any case. Average paternal and maternal age at birth was 37 and 28 years, respectively, suggestive of a new mutation. The presence of a distinct phenotype and hypotonia in these patients with neurofibromatosis is suggestive of a new separate disorder.

Adult↗
PubMed1985

Noonan syndrome: the changing phenotype.

Among the multiple congenital anomalies (MCA) syndromes, the Noonan syndrome (NS) is a cardiofacial syndrome in which affected individuals may be short and mildly mentally retarded. Autosomal dominant inheritance of Noonan syndrome with variable expressivity has been documented in many families. Genetic heterogeneity has been postulated in Noonan syndrome because of the wide phenotypic variability, the relatively high incidence, and the occasional recurrence in sibs with apparently normal parents. Clinical variability is usual in autosomal dominant disorders, and mildly affected individuals may be difficult to recognize as gene carriers. Thus, a family with two or more affected children may simulate autosomal recessive inheritance. We have studied serial and family photographs of NS individuals in order to assess the likelihood of gene carriers' being missed in genetic studies. We have confirmed wide clinical variability within families, and more importantly, we have documented marked change of phenotype with age from the newborn period, infancy, childhood, and adolescence to adulthood. Manifestations in adults may be subtle and some without a known heart defect or other medically significant problems may have been considered normal in the past. Our study, while not ruling out causal heterogeneity, suggests that the change of phenotype with age may have been falsely perceived as clinical heterogeneity. A particular and subtle phenotype must be searched for in parents of affected children.

Adult↗
PubMed1985

The shedding of viable cells into the local lymph by tumours growing in the gut of rats.

Suspensions of syngeneic sarcoma cells were injected into the Peyer's patches of rats from which the mesenteric nodes had been removed. By later cannulating the thoracic duct of such rats it was possible to collect peripheral intestinal lymph that had come directly from the tumour bearing area without being filtered through a regional node. The number of viable tumour cells in the lymph coming from the tumours was monitored by culturing the whole lymph cells in a limiting dilution assay. The tumours grew to a diameter of approximately 1 cm in 25 days and during this time tumour cells were present in the lymph at a ratio of approximately 1 tumour cell per 10(5) lymph cells. In euthymic rats this number declined as the immune response developed. In athymic rats the number increased by approximately 10 fold during the experiments. It was concluded that the shedding of viable cells parallels the linear, not the volumetric dimensions of the tumour.

Animals↗
PubMed1985

The adaptation of enzymes to temperature: catalytic characterization of glucosephosphate isomerase homologues isolated from Mytilus edulis and Isognomon alatus, bivalve molluscs inhabiting different thermal environments.

Homologues of glucosephosphate isomerase (GPI, EC 5.3.1.9) were purified to homogeneity and kinetically characterized from Mytilus edulis and Isognomon alatus, two bivalve molluscs experiencing contrasting thermal environments. The enzyme isolated from I. alatus functions at warmer temperatures (25-35 C) than GPI from M. edulis, a species that inhabits colder marine littoral habitats (5-20 C). The former exhibits apparent first-order (with respect to substrate) catalytic rate constants (Vmax/KM) in vitro that become progressively greater than the mussel enzyme as the assay temperature is raised. Apparent zero-order catalytic rate constants (Vmax) are relatively less differentiated. Catalytic efficiency, defined as the rate at which a catalytic event occurs in either reaction direction for reference standard states (substrate concentrations), is greater for the enzyme from the tropical species (I. alatus) at all realistic combinations of temperature and substrate concentration except for the lowest temperatures and highest substrate concentrations, where the GPI from the boreal/temperate M. edulis is more efficient. This pattern of catalytic divergence appears to be due primarily to differentiation in Vmax/KM. These results and other published data are reviewed and shown to be inconsistent with claims that adaptation of enzymes to higher cell temperatures requires a loss in catalytic efficiency.

Adaptation, Physiological↗
PubMed1985

Chromosomal abnormalities associated with congenital contractures (arthrogryposis).

In a study of 350 patients with multiple congenital contractures (arthrogryposis), 80 (23%) patients had mental retardation or were developmentally delayed. Out of that group of 80 patients, 13 (16%) were found to have abnormal karyotypes. Two of the thirteen had a family history of chromosomal abnormalities without congenital contractures, therefore, 11 patients had chromosomal anomalies which appeared to be associated with the congenital contractures. Five of the eleven (45%) had chromosome mosaicism, three of those had tissue mosaicism. Two had abnormal skin fibroblast cell lines and normal peripheral leukocyte chromosome studies and one had a normal bone marrow karyotype with abnormal peripheral leukocyte chromosome studies. Chromosome studies were done in these patients with congenital contractures because of developmental delay and multisystem involvement, or recognition of clinical features typical of a chromosomal syndrome. We recommend first lymphocyte; and if those are normal, then fibroblast studies be done on all patients with multiple joint contractures and developmental delay, particularly if unusual facial features or multisystem abnormalities are present.

Abnormalities, Multiple↗
PubMed1985

Partial deletion of the short arm of chromosome 3 (3p25----3pter). Further delineation of the clinical phenotype.

Clinical descriptions of individuals with partial deletion of the distal short arm of chromosome three have been reported rarely. A characteristic phenotype has been proposed. We present another patient with this cytogenetic abnormality whose physical and developmental features show similarities with, as well as differences from, previously reported cases. This suggests that the clinical phenotype requires further definition. In addition, gene dosage studies were undertaken on several serum proteins in order to try to map the location of the responsible genes on chromosome three.

Abnormalities, Multiple↗
PubMed1985

Growth analysis in clinical genetics.

The number of genetic and environmental determinants of human growth is very large and their interplay is responsible for the enormously complex phenomenon of prenatal and postnatal growth and simultaneous differentiation in function. Genetic factors participate substantially in determining size at birth, but become more and increasingly important in the realization of inherent potential after the age of two years. Thus, prenatal growth is determined by a greater number of environmental factors than postnatal growth, including parity, pregnancy spacing, maternal age, size, blood pressure, race, health, smoking, alcohol intake, twinning, intrauterine constraint, etc. Galilei's scale effect sets the upper limit of human size, and our surface area determines our metabolic rate and to some extent our life span. Age and rate of pubertal maturation varies with sex, race, and health of the individual, and may be dramatically influenced by numerous environmental and genetic disturbances. One of the most consistent and dramatic effects of autosomal aneuploidy on development is permanent reduction of growth rate, beginning very early in embryonic development. This effect on growth can be interpreted as an abnormality of developmental homeostasis or canalization. Reduced buffering or canalization of growth has been demonstrated in the DS and constitutes most elegant confirmation of the Waddington-Shapiro hypothesis; it ought to be demonstrable also in most if not all of the gonosomal aneuploidies. Thus, an ultrasonographic analysis of embryonic and fetal growth ought to be normal practice in all, not just high--risk pregnancies, and serve as valuable indicator of fetal developmental abnormality if IUGR is found. Because of difference in prognosis and possible difference in obstetric management, ultrasonographers ought to make a distinction in practice between (proportionate) IUGR and (disproportionate) CSOS. Depending on age of onset and severity, reduced prenatal movement can lead to the fetal akinesia sequence including growth retardation of all or part of the fetus. Neurohypotrophy shows that normal innervation is required for normal growth and function of limbs.

Aneuploidy↗
PubMed1985

Genetic aspects of arthrogryposis.

Multiple congenital contractures or arthrogryposis is a birth defect that occurs in approximately one in 3000 births. It can be seen in isolation or in association with other abnormalities. The etiologic and genetic basis of multiple congenital contractures is very heterogeneous. In order to understand the genetic basis and natural history of a specific case, a specific diagnosis must be made. Over 150 conditions are known in which multiple congenital contractures are a predominant sign. In this chapter, the emphasis is on a systematic differential diagnosis and consideration of empiric recurrent risk figures if a specific diagnosis cannot be reached.

Abnormalities, Multiple↗