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Biomedical subjects

R L Teplitz

Publications and source records attributed to R L Teplitz.

At least 91 records · Page 5Linked to original sources
PubMed1976

Ultrastructural differentiation during Drosophila neurogenesis in vitro.

Drosophila melanogaster field neuroblasts differentiate in vitro, and each gives rise to a cluster of about 18 daughter neurons. Electron microscopic observations of single clusters show that axons from daughter neurons form a neuropile within the cluster of cell bodies. The neuropile increases in size and complexity for several hours, during which time chemical, and probably electrotonic, synapses form between neurites. Clear vesicles with diameters of about 35 nm and dense core vesicles with diameters of about 60 and 160 nm were detected. The development of the neuropile indicates that the prerequisite cell recognition phenomena were manifested during differentiation in vitro, and the complexity of the neuropile suggests it may have attained the capacity to process information.

Animals↗
PubMed1976

Ultrastructural differentiation during embryonic Drosophila myogenesis in vitro.

Cultures of embryonic Drosophila melanogaster cells were examined by electron microscopy and events in myogenesis were recorded. Thick and thin myofilaments, T-tubules and sarcoplasmic reticulum all appeared at about the same time, 10.5 hr. This was about 5 hr after the final division of myoblasts and about the time that muscle cells were elongating, aligning and fusing. Sarcoplasm typical of insect muscle was detected by 18.5 hr, as were myotendonal and tendocuticular junctions. Two populations of myocytes were detected, the cytoplasm of one more electron-dense than the other. The only previous report of myofibrilogenesis in invertebrate embryos had described novel mechanisms. In Drosophila embryonic material, however, the sequence of myofibrilogenesis resembled that in postembryonic insect or vertebrate material.

Animals↗
PubMed1975

Effect of peyote on human chromosomes. Cytogenetic study of the Huichol Indians of Northern Mexico.

Fify-seven Huichol Indians with a lifelong individual history and a 1,600-year cultural tradition of ingestion of peyote, a mescaline-containing cactus possessing hallucinogenic properties, were compared with 50 Huichol Indian controls and ten laboratory controls for effects on lymphocyte chromosomes. The frequency of abnormalities in the experimental and control groups did not differ significantly. Our results indicate that multigenerational ingestion of peyote is not associated with abnormalities in lymphocyte chromosomes.

Adolescent↗
PubMed1975

Somatic rearrangement of chromosome 14 in human lymphocytes.

Ataxia-telangiectasia is a rare genetic disorder associated with immune deficiency, chromosome instability, and a predisposition to lymphoid malignancy. We have detected chromosomally anomalous clones of lymphocytes in eight patients with this disorder. Chromosome banding disclosed that the clones are consistently marked by structural rearrangement of the long arm (q) of chromosome 14. A translocation involving 14q was found in clones obtained from seven of the eight patients whereas a ring 14 chromosome was found in a clone obtained from the other. These findings as well as data obtained by others for patients with ataxia-telangiectasia suggest that structural rearrangement of 14q is the initial chromosomal change in lymphocyte clones of patients with this disorder. Chromosomes of lymphocytes from one of the patients were studied before and after the onset of chronic lymphocytic leukemia. Before leukemia was diagnosed, the patient had a lymphocyte clone with a 14q translocation. This clone appears to have given rise to the leukemic cells. We hypothesize that structural rearrangement of 14q is directly related to abnormal growth of lymphocytes and that it may be a step toward the development of lymphoid malignancies. Increasing evidence, provided by others, for the nonrandom involvement of 14q in African-type Burkitt's lymphoma and other lymphoid neoplasms further strengthens this hypothesis.

Adolescent↗
PubMed1975

Repair of UV damaged DNA in systemic lupus erythematosus.

The NZB/NZW hybrid mouse is an animal model of human systemic lupus erythematosus (SLE). Two breeding schemes were devised using NZB, NZW, B/W, and CBA mice, which permit definitive decisions regarding genetic and/or viral origin of the disease. It is proposed that at least two factors must be involved: (1) a genetic abnormality producing hyper-responsiveness to nucleic acid antigens, and (2) a DNA repair defect which results in liberation of DNA and RNA when cells are lethally injured. Evidence is presented for a DNA repair deficit in human SLE lymphocytes following in vitro irradiation with ultraviolet (UV) light. Lymphocytes from adult New Zealand and control mice were found to lack normal amounts of endonuclease necessary for repairing UV damage.

Adult↗
PubMed1972

Differentiation of neuromuscular junctions in cultures of embryonic Drosophila cells.

Cultures were prepared of embryonic cells from Drosophila melanogaster. Neurons and myocytes differentiated in vitro from their respective stem cells. Electron microscopy showed that neuromuscular junctions formed where axons contacted myocytes. Electrical stimuli were applied to axons and these caused contractions of innervated myocytes. This is the first report of insect or other invertebrate neuromuscular junctions differentiating in vitro. In addition, this is the first system reported in which the neurons, myocytes, and junctions are completely differentiated in vitro from neuroblasts and myoblasts.

Animals↗