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Y N Liu

Publications and source records attributed to Y N Liu.

44 records · Page 3Linked to original sources
PubMed1985

Functional analysis of macrophage hybridomas. III. Inhibition of lymphocyte blastogenesis and tumor proliferation.

Four cloned macrophage hybridoma cells prepared by fusion of splenic adherent cells with a P388D1 macrophage tumor markedly inhibited the growth of lymphocytes and tumor cells. Macrophage clones 5, 8, 63, and 64 are strong inhibitors of B-cell blastogenesis, T-cell blastogenesis, and tumor proliferation, while the P388D1, tumor line and clones 13, 59, and 67 demonstrated little inhibitory activity in all three systems. The inhibitory effect of macrophage hybridomas can be detected within 8 hr, although greater inhibition was noted following longer incubation. The correlations among these three assay systems suggest that similar mechanisms may be involved. The data indicate that the inhibition of cell proliferation was not due to cell lysis. Furthermore, the inhibition of lymphocyte proliferation in Con A-stimulated cultures was not accompanied by inhibition of lymphokine production in the same cultures. Neither prostaglandins nor hydrogen peroxide appear to be primarily responsible for growth inhibition. The inhibitory properties of these macrophage hybridoma lines represent a stable phenotype and provide a homogeneous source of cells for further analysis of the phenomenon.

Animals↗
PubMed1985

Effect of circadian rhythm on bronchomotor tone after deep inspiration in normal and in asthmatic subjects.

Bronchomotor tone after deep inspiration and bronchial responsiveness to methacholine were studied at 4:00 A.M. and 4:00 P.M. in 14 normal and 13 asthmatic subjects. Bronchomotor tone was assessed with respiratory resistance (Rrs) measured by the forced oscillation method. Bronchial responsiveness to methacholine and baseline Rrs were higher at 4:00 A.M. than at 4:00 P.M. in both normal and asthmatic subjects (p less than 0.01). The difference in methacholine threshold between 4:00 P.M. and 4:00 A.M. In asthmatics was similar to that in normal subjects. Immediately after deep inspiration, Rrs decreased more at 4:00 A.M. than at 4:00 P.M. In normal subjects. In contrast, asthmatic subjects showed a significantly greater immediate increase in Rrs after deep inspiration at 4:00 A.M. than at 4:00 P.M. It is suggested that the bronchoconstrictive effect after deep inspiration is a distinguishing characteristic of asthmatics.

Adult↗
PubMed1984

Effect of inspiratory flow rate on bronchomotor tone in normal and asthmatic subjects.

The effect of the inspiratory flow rate during deep inspiration on the regulation of bronchomotor tone was studied in nine normal and 22 asthmatic subjects. Changes in bronchial tone were assessed by respiratory resistance measured by an oscillation method. In normal subjects with bronchoconstriction induced by methacholine a rapid deep inspiration reduced respiratory resistance more than a slow deep inspiration. Asthmatic subjects with spontaneous airway narrowing showed an increase in respiratory resistance after deep inspiration that was greater after rapid than after slow deep inspiration. On the other hand, in asthmatics with methacholine induced bronchoconstriction, bronchodilatation occurred after deep inspiration and this was also greater after rapid than after slow deep inspiration. Lignocaine inhalation attenuated both bronchoconstriction and bronchodilatation induced by both slow and rapid deep inspiration. These results suggest that the effects of deep inspiration are mediated at least in part via receptors in the airways. It is suggested that in asthmatic patients with spontaneous bronchoconstriction irritant receptor activity will be increased in proportion to the speed of inspiration. After methacholine induced bronchoconstriction stretch receptor activity is likely to behave in a similar fashion, leading to an opposite effect.

Adult↗
PubMed1984

Hapten-specific T cell responses to 4-hydroxy-3-nitrophenyl acetyl. XIV. Carrier requirement for suppressor cell induction.

The carrier requirements for the induction of helper and suppressor T (Ts) cells were compared. Although H-2-linked Ir genes control the development of helper T cells and hapten-specific B cells, they do not influence Ts3 generation. That is, GL phi nonresponder C57BL/6 mice can generate NP-specific Ts3 cells after priming with NP-GL phi. The Ts3 cells generated under these conditions are functionally and phenotypically identical to the NP-specific Ts3 cells previously characterized. Furthermore, these Ts3 populations can be specifically depleted with a monoclonal anti-idiotope antibody prepared against monoclonal anti-NP antibodies. By using related polymers, carrier effects on Ts3 induction were noted. NP-D-GL and NP-Ficoll failed to induce Ts3 cells, whereas NP-L-GL induced this suppressor subset. The data demonstrate that Ts3 induction is independent of the carrier requirements involved in helper T cell induction and is not dependent upon B cell priming. The implications of these results with regard to the mechanisms of Ts3 induction are discussed.

Animals↗
PubMed1981

Idiotypy of clonal responses to influenza virus hemagglutinin.

Anti-idiotype antisera were raised in syngeneic (BALB/c mice) and homologous (A/J mice) systems to study the cross-reactive idiotypes among monoclonal antibodies to PR8 and B/Lee virus HA and the expression of these idiotypes during primary and secondary antiviral responses of BALB/c mice. Extensive idiotypic cross-reactivity was demonstrated among monoclonal antibodies specific for distinct antigenic determinants on PR8 hemagglutinin (HA). The study of idiotypy of monoclonal antibodies against the same or overlapping antigenic determinants on B/Lee HA showed that these monoclonal antibodies may bear (a) a true individual idiotype not shared by other monoclonal antibodies, (b) idiotypes shared by few monoclonal antibodies, and (c) true cross-reactive idiotypes shared by all of these monoclonal antibodies. In contrast, no cross-reactive idiotypes were detectable among monoclonal antibodies to B/Lee HA and monoclonal antibodies to PR8 HA. Furthermore, we have shown that the anti-idiotype antibodies we used recognize determinants on monoclonal antibodies closely associated with antigenic binding sites. Finally, studies of the idiotypes expressed during primary and secondary antiviral HA responses of mice immunized with B/Lee virus revealed persistence of some idiotypes during both primary and secondary responses, whereas others were only expressed in the primary or secondary response.

Animals↗