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Biomedical subjects

L Loh

Publications and source records attributed to L Loh.

At least 55 records · Page 3Linked to original sources
PubMed1982

Murine cytomegalovirus-induced immunosuppression.

The mechanism of murine cytomegalovirus-induced immunosuppression was investigated by examining the roles played by lymphocytes and adherent cells derived from spleens of infected SWR/J mice. As few as 100 infected cells per spleen were correlated with complete abrogation of mitogen responses at 4 and 5 days after infection. In a series of cell mixing experiments it was shown that the deficiency in infected spleens was due partly to the adherent cells, which apparently secreted an immunosuppressive factor, and partly to the infected lymphocytes, which upon exposure to this factor could no longer respond to concanavalin A presented to them by normal adherent cells.

Animals↗
PubMed1981

Pain due to lesions of central nervous system removed by sympathetic block.

Eight patients were studied in whom a lesion within the central nervous system caused constant pain and hyperpathia. Blockade of the sympathetic supply to the periphery was carried out in each patient by stellate ganglion block or intravenous infusion of guanethidine 15 mg in 30 ml saline into a limb on the affected side. On almost every occasion the pain and hypersensitivity were reduced, sometimes completely. Thus chronic pain and hyperpathia arising from a lesion in the central nervous system may be abolished by blocking the sympathetic supply to the periphery; this effect may be achieved when not all the peripheral nerves of the affected region have had their sympathetic nerve supply blocked. Such blockade may be worth repeating in the hope of achieving lasting relief of the intractable pain.

Adult↗
PubMed1981

Murine cytomegalovirus infection in the spleen and its relationship to immunosuppression.

An attempt was made to correlate murine cytomegalovirus-induced immuno-suppression with the presence of virus-infected cells in the spleen. For this purpose, SWR/J mice were infected with murine cytomegalovirus, and spleens were removed periodically and assayed for the presence of infectious centers in different cell populations and for their capacity to respond to mitogens. The maximal degree of immunosuppression correlated with the peak in adherent cell infectious centers. This was followed by a rapid rise in the number of cells per spleen (splenomegaly), a more gradual return to normal responsiveness to mitogens, and a rapid disappearance of infectious centers. These results add more support to the hypothesis that murine cytomegalovirus-induced immunosuppression is caused indirectly by infection of adherent spleen cells.

Animals↗
PubMed1980

Regional lung function in bilateral diaphragmatic paralysis.

1. The distribution of regional function in the lungs of six patient with bilateral diaphragmatic paralysis was investigated by continuous inhalation and infusion of the radioactive gases 81mKr and 85mKr during tidal breathing. 2. In the supine and right lateral decubitus postures the vertical distribution of ventilation per unit alveolar volume was less in the dependent zones, the reverse of that found in normal subjects. In the upright posture ventilation was slightly decreased at the lung base. Perfusion per unit alveolar volume was more uniformly distributed than normally in the upright posture, and decreased from superior to inferior in the supine posture. In the lateral decubitus posture, perfusion of the lower lung was greater than that of the upper. Ventilation/perfusion ratios were more uniformly distributed in the patients than in normal subjects, except in the right lateral decubitus posture. 3. Alterations in the distribution of ventilation may be explained in terms of the altered mechanical interaction of chest wall, mediastinal and abdominal contents, with selective use of intercostal and accessory muscles. The effects on the distribution of blood flow are probably related to the low end-expiratory lung volume.

Adult↗
PubMed1980

Immunosuppressive effect of murine cytomegalovirus.

Murine cytomegalovirus suppressed the ability of spleen cells to respond to mitogens in vitro. The degree of suppression was proportional to the multiplicity of infection. This effect could not be explained by cytolysis of lymphocytes, an alteration in the kinetics of the response to mitogen, or a direct competition between virions and mitogen molecules for cell-surface receptors. Nor was it due to simple contact between cell and virus, since ultraviolet-inactivated murine cytomegalovirus failed to suppress the response to mitogens. Reconstitution experiments were performed which involved mixing various combinations of infected and uninfected macrophages and lymphocytes. Under these conditions, it was found that the infected macrophages and lymphocytes. Under these conditions, it was found that the infected macrophages had an impaired capacity to mediate the response ot T lymphocytes to concanavalin A. This suggests that murine cytomegalovirus may cause immunosuppression indirectly by interfering with macrophage function.

Animals↗
PubMed1980

Effects of regional guanethidine infusion in certain painful states.

Guanethidine was infused by the regional intravenous technique into upper and lower limbs of patients with painful hyperpathic states, due to peripheral or central lesions. The relief of pain and hyperpathia occurred within 20 minutes of infusion and lasted between three and 128 hours; in a few patients, the relief has lasted for months. Great reduction in skin conductance and vasodilatation occurred, there being marked variation in the time of onset and duration of these effects. In some cases there was marked pilo-erection. Guanethidine given in this way did not completely block the sympathetic control of digital blood-vessels. There were no effects on sensibility of normally innervated regions.

Chronic Disease↗
PubMed1979

Errors in fuel cell oxygen analysers during NEEP.

A fuel cell oxygen analyser was found to underread during the application of negative end-expiratory pressure. Further investigation revealed that air leaks into the analyser head through the plastic housing and causes the analyser to read low. A remedy is suggested.

Oxygen↗
PubMed1979

Interaction of murine cytomegalovirus with separated populations of spleen cells.

Mouse spleen cultures were infected with murine cytomegalovirus, either before or after separating the cells into various classes, and the growth of virus and production of infectious centers were measured in each cell class. The separation techniques, which were used in various combinations, comprised: adherence to plastic surfaces; adherence to nylon wool columns; gamma irradiation; and treatment with anti-immunoglobulin serum plus complement. The "macrophage population" took up most of the input virus, as shown by autoradiography of spleen cells infected with radioactive virus. These cells formed infectious centers but replicated the virus only transiently. In contrast, the "B-lymphocyte population" contained a minor cell fraction which was permissive for replication. The "T-lymphocyte population" appeared to be nonpermissive for replication and did not produce infectious centers.

Animals↗
PubMed1978

Preservation of the pulmonary vasoconstrictor response to alveolar hypoxia during the administration of halothane to dogs.

The action of halothane on the pulmonary vasoconstrictor response to unilateral alveolar hypoxia was studied in two groups of dogs. In the first group the redistribution of blood flow between the two lungs was studied with a radioactive isotope method, which provided intermittent measurements, whilst in the second group the distribution of blood flow was observed continuously. In both groups there was no significant alteration of the hypoxic vasoconstrictor response with inspired halothane concentrations varying from 0.5 to 1.5%.

Animals↗