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Biomedical subjects

L E Davis

Publications and source records attributed to L E Davis.

At least 217 records · Page 12Linked to original sources
PubMed1979

Adrenoleukodystrophy and adrenomyeloneuropathy associated with partial adrenal insufficiency in three generations of a kindred.

Four cases of adrenoleukodystrophy (ALD) and one case of adrenomyeloneuropathy (AMN) have developed in a kindred over three generations demonstrating that AMN is a clinical variant of ALD. Pituitary-adrenal function studies were performed in 10 family members, including two affected males and four females identified as carriers of ALD/AMN. No pituitary-adrenal abnormality was found in the carriers. However, basal morning plasma adrenocorticotropic hormone (ACTH) levels were markedly elevated in the two males with ALD and AMN, despite the fact that they had no clinical signs of adrenal insufficiency and that morning plasma cortisol levels and their response to maximal exogenous ACTH stimulation appeared to be normal. In addition, the integrated 24-hour response to the administration were also subnormal in these two cases. Thus, people with ALD and AMN may have subclinical partial adrenocrotical insufficiency. No other endocrinologic dysfunction was identified.

Adolescent↗
PubMed1979

Experimental viral infections of the temporal bone. I. Experimental otitis media due to vaccinia virus in hamsters.

Clinical and pathologic studies of patients with smallpox suggest that conductive hearing loss is a frequent complication of smallpox and that it is due to otitis media. A possible experimental model for this hearing loss has been developed by study of the pathogenesis of acute vaccinia virus infections of hamster middle ears. Infant hamsters developed severe necrotic otitis media, and vaccinia viral antigen was demonstrated by fluorescent antibody staining in large confluent areas of epithelial cells lining the middle ear. Juvenile hamsters developed a patchy, less severe infection of the middle ear, most of which present along the tympanic membrane and middle ear ossicles, Adult hamsters did not develop middle ear infection. These findings support the argument that variola (smallpox) virus can cause otitis media in humans and that viral infection of the middle ear may be the cause of hearing loss.

Acute Disease↗
PubMed1979

Production of nerveless Hydra attenuata by hydroxyurea treatments.

Hydroxyurea was used to produce hydra with varying nerve cell densities including a new type of nerveless animal. Hydra attenuata were treated with 10(-2) M hydroxyurea. By 23 days after treatment, 2 populations of animals are in culture. Both have a decrease in nerve cells. The first is a normal-coloured feeding animal (HU-R) and is recovering while the second is a pale non-feeding animal (HU-P). HU-P animals resemble nerveless animals in their lack of behavioural responses but they contain about 2% nerve cells. Upon hand feeding, some HU-P animals will recover but most will produce nerveless buds. Neverless hydra produced by hydroxyurea resemble nerveless animals produced by other techniques, in their behavioural, morphological and developmental properties. Normal animals, as cultured and in regeneration experiments, show a compact tentacle number distribution pattern with a small variance. Nerveless animals show broad tentacle distribution patterns with increased means and variances. It is suggested that a normal tentacle number regulatory mechanism is lacking or diminished in nerveless animals. This defect is correlated with hypostomal circumference and with nerve cells.

Animals↗
PubMed1978

Bell's palsy and secondary syphilis: CSF spirochetes detected by immunofluorescence.

Although Bell's palsy is usually idiopathic, occasional cases may have an identifiable infectious cause. When facial paralysis results from syphilis, it usually develops during the tertiary meningovascular stage. We report a 30-year-old man with secondary syphilis who developed facial paralysis associated with acute syphilitic meningitis. Spirochetes were identified in the cerebrospinal fluid by immunofluorescence using standard reagents from the fluorescent treponemal antibody absorption (FTA-ABS) test. Patients with Bell's palsy should be screened for syphilis with a blood FTA-ABS test, and treatment with corticosteroids should be considered only after an infectious cause has been excluded.

Adult↗
PubMed1977

Chronic progressive poliomyelitis secondary to vaccination of an immunodeficient child.

We investigated an immunodeficient child in whom chronic progressive poliomyelitis developed after she had received live oral poliovirus vaccine. Poliovirus, Type II, was isolated from throat and stool during life and from several sites within the brain at autopsy. The brain isolate was classified as vaccine-like on the basis of temperature sensitivity and antigenic markers. However, in the monkey neurovirulence test, the brain isolate produced moderately severe lesions throughout the spinal cord and brainstem and appeared nonvaccine-like. Thus, the brain isolate demonstrated a dissociation between the antigenic and neurovirulence markers. Our observations suggest that, under unusual circumstances, such as immunodeficiency, attenuated poliovirus can produce a chronic progressive neurologic disease. This case also emphasizes the need to diagnose immunodeficiency as early as possible, so that live-virus vaccines will not be administered.

Agammaglobulinemia↗
PubMed1977

Cellular mechanisms of stimulation of bud production in Hydra by low levels of inorganic lead compounds.

Treatment of Hydra with subtoxic levels of inorganic lead compounds (lead nitrate and lead chloride) for perods ranging from 5 min to one hour causes a temporary increase in bud production as compared to untreated control animals. This effect can be inhibited by the addition of large amounts of calcium chloride to the culture medium. The increased rate of budding is preceded by a dramatic increase in the number of nerve cells per animal, which is first observed within six hours after lead treatment. This appears to be the result of an increased rate of mitosis in the undifferentiated interstitial cells and their subsequent differentiation into nerve cells. The total number of cells per animal also increases after exposure to lead compounds, suggesting that lead may act as a general mitotic stimulator of all dividing cell types in Hydra.

Animals↗
PubMed1977

Antibodies to human caudate nucleus neurons in Huntington's chorea.

Antibodies reacting with neuronal cytoplasmic antigens present in normal human caudate and subthalamic nuclei were detected in 37 of 80 probands afflicted with Huntington's disease (HD). IgG antibodies were detected by immunofluorescence using frozen sections of unfixed normal human and rat brain. Specificity of IgG binding was confirmed using pepsin F(ab')2 fragments of IgG isolated from positive sera. In vitro complement fixation of IgG antibody was detected in 22 of 31 sera tested. Neuronal cytoplasmic antigens reacting with positive HD sera were diminished after trypsin or RNAase treatment of tissue sections but were not removed by DNAase, neuraminidase, EDTA, or dithiothreitol treatment. Antibody staining of neurons could be removed after absorption with isolated caudate nucleus neurons or by using perchloroacetic acid extracts of caudate nucleus. Prevalence of antibody reacting with neuronal cytoplasm was 3% in 60 normal controls and 6% among a wide variety of patients with diverse neurological disorders. However, one-third of 33 patients with Parkinson's disease showed presence of antineuronal antibody. Among patients with HD, a significant association was noted between duration of clinical disease greater than 7 yr and titers of antibody of 1:2 or greater (P less than 0.001). When 115 family members of HD probands were tested, 30% of unaffected spouses showed presence of antineuronal antibody. 23.2% of first-degree relatives at risk for developing HD was also positive (P less than 0.001). 10.5% of second-degree relatives showed presence of antineuronal antibody. These data may support an environmental or infectious factor somehow involved in the ultimate expression of HD.

Adult↗
PubMed1976

The general occurrence of intramitochondrial crystals in Hydra cells.

Intramitochondrial crystals are found in normal Hydra as well as in animals undergoing various conditions (budding, regenerating, eserine-treated, and sexual). They appear in all regions of the animal, but seem to be more prevalent at or near the extremities: hypostome, tentacles and basal disk. They are found in all of the seven basic cell types: interstitial, cnidocyte, nerve, epithelio-muscular, gland, mucous and digestive cells. The chemical nature of the intramitochondrial crystals is unknown and their significance remains speculative.

Animals↗
PubMed1976

Anatomy and ultrastructure of the excretory system of the lizard, Sceloporus cyanogenys.

The anatomy and ultrastructure of the lizard kidney (Sceloporus cyanogenys) have been studied by light and electron microscopy. The number of glomeruli was counted in serial sections and estimated to be 2,000 (in the two kidneys). Beginning with the glomerulus and Bowman's capsule the nephron segments are sequentially: (a) proximal tubule; (b) intermediate ciliated segment consisting of a proximal and distal part; (c) distal tubule, which can be divided into two segments, followed by (d) connecting tubule and (e) initial collecting duct. The initial collecting ducts from several nephrons open into the collecting duct. Tubular epithelium in this lizard has similarities to that of other reptiles. The lateral borders do not overlap like in mammals, but interdigitate by fingerlike projections. The length of the nephron segments was measured in disected tubules and the diameter was measured on light and electron micrographs. From these measurements estimates of inner tubular surface area were made. Together with data from physiological studies (Stolte et al., '76; Schmidt-Nielsen, '76) the estimated surface area was used to calculate transport rates per unit area across the epithelium. Comparisons of structure and transport rates per unit area across the epithelium. Comparisons of structure and transport rates were made between S. cyanogenys and other reptiles and mammals.

Animals↗
PubMed1976

Experimental viral infections of the inner ear. I. Acute infections of the newborn hamster labyrinth.

Acute viral infections of the inner ear were produced in neonatal hamsters. Viruses were inoculated percutaneously through the temporal cartilage into the endolymphatic and perilymphatic spaces of the labyrinth or were inoculated intracerebrally to reach the perilymphatic spaces via the cochlear aqueduct. Selective vulnerability of inner ear structures was demonstrated using a variety of viruses. Influenza virus infected only the mesenchymal cells of the perilymphatic channels of the cochlea; mumps virus infected principally endolymphatic structures; herpes simplex virus infected primarily the sensory cells of the labyrinth; and rubeola and vaccinia viruses infected both perilymphatic and endolymphatic cells.

Acute Disease↗
PubMed1975

Histological and ultrastructural studies of the basal disk of Hydra. III. The gastrodermis and the mesoglea.

The gastrodermis and mesoglea of the basal disk of Hydra were investigated to conclude a three-part series of papers. The gastrodermis is composed of digestive cells (most predominant cell type), mucous and nerve cells (both immature and fully differentiated). The principal function of the digestive cells appears to be storage of protein, lipid and glycogen reserves which are utilized by neighboring cells. Mucous cells apparently use some of the reserves to synthesize their secretions which lubricate cells and prevent cell damage during egestion of waste through the aboral pore. The function of the gastrodermal nerve cells is uncertain. The mesoglea of the basal disk, contains the same structural components as seen in other regions of the polyp. It is reasonable to assume that it maintains the same function of cell adhesion and migration. As the mesoglea converges on the aboral pore, it loses its structural integrity and cells are sloughed off the column.

Animals↗
PubMed1975

Combined immunodeficiency and vaccine-related poliomyelitis in a child with cartilage-hair hypoplasia.

Patients previously described with cartilage-hair hypoplasia, a distinctive form of short-limbed dwarfism, have been found to have deficient cell-mediated immunity with intact antibody-mediated immunity. The patient with cartilage-hair hypoplasia described in the present report is unusual in that she had both deficient antibody-mediated immunity and deficient cell-mediated immunity. In addition, she developed severe, vaccine-related paralytic poliomyelitis. This complication suggests that live viral vaccines should not be administered to children with short-limbed dwarfism until the form of short-limbed dwarfism is established and immunologic evaluation is performed when indicated.

Bone and Bones↗