Biomedical subjects

M Travis

Publications and source records attributed to M Travis.

At least 37 records · Page 2Linked to original sources

PubMed1987

Electrophysiological evaluation of a partial agonist of dopamine receptors.

The ergot derivative trans-dihydrolisuride (TDHL) was tested for its effects on firing rates of dopaminergic (DA) neurons located in the substantia nigra pars compacta of chloral hydrate-anesthetized rats. Using extracellular single-barreled microelectrodes, DA neurons were identified by their long duration, positive-negative action potentials and their slow bursting pattern of spontaneous firing, as well as by the location of recording sites through histological recoveries of dye deposits. Like haloperidol and clozapine, which are full DA receptor antagonists, TDHL antagonized the depression in DA neuron firing induced by systemic amphetamine. However, where full antagonists completely reversed the amphetamine effect, TDHL could do so only partially, the maximal effect being around half. Like DA agonists, but unlike DA antagonists, TDHL also depressed the spontaneous firing rates of DA neurons. But whereas the full agonist apomorphine completely inhibited firing of DA neurons, TDHL only depressed firing rates by about half, even at high doses. These data support the contention that TDHL is a partial DA agonist.

Amphetamine↗

PubMed1986

Developmental progression of myosin gene expression in cultured muscle cells.

Myosin heavy chains are encoded by distinct members of a multigene family at different stages of muscle development. Study of the underlying regulatory mechanisms has been hindered because transitions in myosin expression have not been readily attained in tissue culture. Here we show a transition from early (fetal) to late (perinatal/adult) myosins defined by two monoclonal antibodies, F1.652 and N3.36, in the myotubes of mouse C2C12 cells. On day 1 of differentiation, essentially all myosin was early myosin. By day 8, early myosin dropped to 25% of its day 1 value and was replaced by late myosin. The transition occurred without neural contact, connective tissue components, or complex substrates, suggesting that its regulation may be intrinsic to the muscle cell. Our results demonstrate that a developmental progression in myosin gene expression, which occurs rapidly, with high frequency, and under relatively simple conditions, is now amenable to molecular analysis in cultured muscle cells.

Animals↗

PubMed1984

Intrathymic lymphopoiesis: stromal cell-associated proliferation of T cells is independent of lymphocyte genotype.

We analyzed the genetic restriction of direct cell-cell interactions between thymocytes and a) cortical epithelial cells, b) macrophages, and c) medullary dendritic cells in the mouse thymus. Thymectomized (C3H X C57BL/Ka)F1 hybrid mice were doubly grafted with P1 and P2 neonatal thymus grafts, were lethally irradiated, and were reconstituted with a mixture of P1 and P2 bone marrow cells which differed in the Thy-1 locus. The contributions of both parental inocula to the composition of the free and stromal cell-associated T cell compartments were analyzed separately in thymic grafts of each parental strain. The lymphoid composition in both compartments essentially reflected the peripheral T cell-chimerism in the host. The development of lymphostromal complexes was not restricted by the genotype of the partner cells. Statistical analysis of the distributions of P1 and P2 T cells among free thymocytes and within individual lymphostromal complexes, however, suggests that the T cells of an individual complex are the progeny of oligoclonal proliferation. Thus, both epithelial cells and bone marrow-derived stromal cells seem to be involved in different stages of intrathymic lymphopoiesis.

Animals↗

PubMed1983

Habitat segregation among larval mosquitoes (Diptera: Culicidae) in tire yards in Indiana, USA.

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Aedes↗

PubMed1983

Effect of physical training on myocardial enzyme activities in aging rats.

Male Fischer rats of four age groups were subjected to a 3-mo exercise training program that consisted of a gradual increase to 1 h/day of forced swimming. Exercise was initiated at 1, 6, 12, or 17-22 mo of age. After the training period there was an increase in the heart weight relative to body weight in all groups, but heart weight was increased only in the two oldest groups. The specific activities of both actomyosin ATPase and creatine kinase isolated from cardiac muscle decreased with age. In animals that started exercise training at 6 mo of age the activities of both enzymes were higher than that of the age-matched sedentary controls, but the oldest animals (17-22 mo) responded negatively (i.e., a decreased enzymatic activity compared with sedentary individuals of the same age). These results suggest that, after a certain age, the initiation of endurance exercise may not result in the same adaptive response as occurs in younger animals. In the case of actomyosin ATPase this may be a consequence of a different distribution of myosin isozymes.

Adenosine Triphosphatases↗

PubMed1981

Marrow-thymus interactions during radiation leukemogenesis in C57BL/Ka mice.

Transplantation of thymus and bone marrow cells from irradiated C57BL/Ka mice demonstrated the presence of potentially neoplastic cells in the thymus at 30 to 60 days postirradiation. During the same interval, no such cells could be detected in the bone marrow; moreover, the capacity of bone marrow cells to repopulate the thymus was impaired severely. These observations suggest that the primary site of neoplastic transformation in irradiated C57BL/Ka mice is the thymus rather than the bone marrow and that impaired thymic regeneration is a critical step in radiation leukemogenesis in mice.

Animals↗

PubMed1978

Management of a patient with hereditary angioneurotic edema.

Patients with a history of hereditary angioneurotic edema can adequate and safely have nonelective surgical procedures performed with proper preoperative and postoperative management. Deficient amounts of C1 esterase inhibitor can be replaced with fresh frozen plasma; capillary permeability and spreading edema can be prevented with antifibrinolytic agents such as Amicar. Once edema has occurred peripherally and no laryngeal symptoms are present, conservative treatment is advisable. When epiglottic and laryngeal edema occurs, intubation or tracheostomy is preferred for maintenance of airway until the edema subsides. During oral surgical procedures, minimal surgical trauma must be achieved. Edema that involves the airway presents the greatest danger to patients. These attacks are usually associated with dental or some sort of oral or pharyngeal manipulation.

Angioedema↗

PubMed1975

Focal infection and transformation in situ of thymus cell subclasses by a thymotropic murine leukemia virus.

Studies on the maturational lineages of thymic lymphocytes have revealed several subclasses which are distinguishable on the basis of cell size, topographic distribution within the thymus, DNA synthetic and mitotic activity, migratory behavior, and other properties. Strain C57BL/Ka mice were inoculated with radiation leukemia virus at different concentrations, and tissues were removed at defined intervals. Sequential sections were analyzed for virus-specific cytoplasmic antigen expression, for morphological evidence of neoplastic transformation, and for alkaline phosphatase activity. The first detectable sign of MuLV infection was the focal appearance of cytoplasmic viral antigens in cells of the outer thymic cortex, followed by coalescence of such foci and, several weeks later, by the appearance of morphologically transformed and alkaline phosphatase-positive cells, again often focally distributed in the outer thymic cortex. These observations strongly suggest that the large, mitotically active cells of the outer thymic cortex are the principal source of target cells for both productive infection and subsequent lymphoma induction by the virus.

Alkaline Phosphatase↗

PubMed1970