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Biomedical subjects

H Levine

Publications and source records attributed to H Levine.

At least 145 records · Page 8Linked to original sources
PubMed1986

A technique to model the nasal airway for aerodynamic study.

This article presents a new technique for creation of a model that can be used to study the aerodynamics of the nasal airway. The model is employed to determine parameters used to calculate nasal resistance and modified to compare various types of nasal obstruction. It quantitatively compares the importance of septal deviation, turbinate size, and nasopharyngeal port size to airflow. A new parameter of nasal resistance is introduced.

Acrylates↗
PubMed1985

Expression of interleukin 2 receptors and binding of interleukin 2 by gamma interferon-induced human leukemic and normal monocytic cells.

Gamma interferon induced surface expression of interleukin 2 (IL-2) receptors on normal human monocytes and the monocytoid cell lines U937 and HL60. These receptors were detected by anti-IL-2 receptor monoclonal antibodies, and U937 IL-2 receptors were indistinguishable from T lymphocyte IL-2 receptors by immunoprecipitation. Also, U937 IL-2 receptors bound biologically active IL-2. These results suggest a role for monocyte IL-2 receptors in T cell/monocyte interaction during an immune response.

Antibodies, Monoclonal↗
PubMed1985

Class II major histocompatibility complex molecules regulate the development of the T4+T8- inducer phenotype of cultured human thymocytes.

We demonstrate that a variety of Ia+ cells has the ability to promote the development of human T4+T8- thymocytes in vitro. Prolonged thymocyte culture in the absence of Ia+ accessory cells results in a predominantly T8+T4- cell population. The generation of T4+ cells in the presence of irradiated Ia+ cells could be suppressed up to 70% by a monoclonal antibody directed against a nonpolymorphic epitope on HLA-DR. Using two-color fluorescence sorting techniques, we were able to identify the activated T4+T8+ thymocyte as the cell that interacts with Ia and gives rise to the T4+T8- cell subset. These results directly and specifically implicate class II major histocompatibility complex molecules in the differentiative pathway of the human thymocyte.

Antibodies, Monoclonal↗
PubMed1985

Coexpression of T4 and T8 on peripheral blood T cells demonstrated by two-color fluorescence flow cytometry.

Using two-color fluorescence flow cytometry, we were able to detect the presence of small numbers of T4+T8+ cells (about 3%) in freshly isolated peripheral T cell populations derived from normal healthy donors. Coexpression of T4 and T8 was predominantly found on large blastlike cells and appeared to be related to activation. Stimulation of peripheral T cells with concanavalin A (Con A) for 5 days resulted in the generation of up to 60% of T4+T8+ cells. Coexpression was accompanied by a twofold increase in the number of T8 antigenic sites per cell. The T4+T8+ cells in lectin-stimulated cultures expressed high levels of the activation antigens T9, T10, and the IL-2 receptor but lacked T6, an antigen found on a majority of stage II thymocytes. Coexpression of T4 and T8 appeared to be a transitory process, because prolonged culture of T cells in the absence of lectin resulted in the loss of the T4+T8+ phenotype. Our data suggest that T cell activation in peripheral blood results in the generation of a T4+T8+ cell population which is distinct from previously described thymic and peripheral blood cells. Because T4 and T8 molecules may interact directly with MHC antigens, coexpression of these molecules may have an important role in immune function.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1985

Functional characterization of LFA-1 antigens in the interaction of human NK clones and target cells.

In the present studies we analyzed the role of LFA-1 antigens in the interaction between NK clones and target cells. The use of various cloned NK cell lines allowed us to analyze homogeneous populations of NK cells which ordinarily comprise only a small fraction of peripheral blood lymphocytes and are extremely heterogeneous with respect to phenotype and specificity. Indirect immunofluorescence with monoclonal antibodies against the alpha (MHM24) and beta (MHM23) chains of the LFA-1 antigen revealed similar patterns of positive reactivity with all NK clones. Both monoclonal antibodies exerted a significant blocking effect on NK cytotoxicity against target cells such as Molt-4 and CEM, whereas the inhibition was very weak against other targets such as K562 and HSB cells. Additive blocking effects were seen when both monoclonal antibodies MHM23 and MHM24 were added to the cytotoxicity assays. When we compared the inhibitory effect of MHM23 and MHM24 on uncultured peripheral blood NK cells and IL 2-activated NK cells, inhibition of cytotoxicity also was found to be primarily dependent on the individual target cells. Thus, the inhibitory activity of anti-LFA-1 antibody was shown to be independent of the phenotypic and functional heterogeneity of the NK clones, activated NK cells, and unstimulated NK cells utilized in these studies. These blocking effects were found to be independent of the LFA-1 antigen expression on the target cell membrane and inhibition occurred only when antibody was bound to the effector cells. Comparison of the effects of anti-LFA-1, anti-T3, and anti-clonotypic antibodies against a Ti-like structure of different NK clones with a mature T cell phenotype demonstrated that each of these antibodies acts on the effector cells in an independent and additive fashion. However, unlike T3 and NKTa antigen, LFA-1 antigen expression is not modulated by cell surface interaction with antibodies specific for this molecule.

Antibodies, Monoclonal↗
PubMed1985

Differential expression of HLA-DR antigens in subsets of human CFU-GM.

Expression of HLA-DR surface antigens by granulocyte/monocyte colony-forming cells (CFU-GM) may be important in the regulation of proliferation of these cells. Using immunological techniques to enrich for progenitor cells, we investigated the expression of HLA-DR in subsets of CFU-GM. "Early" (day 14) CFU-GM express higher levels of HLA-DR than do "late" (day 7) CFU-GM. Among late CFU-GM, cells destined to form monocyte (alpha-naphthyl acetate esterase-positive) colonies express higher levels of HLA-DR than do CFU-GM destined to form granulocyte (chloroacetate esterase-positive) colonies. Because high-level expression of DR antigen was a marker for monocyte differentiation, we examined several lymphokines for their effects on both DR expression and in vitro commitment to monocyte differentiation by myeloid precursor cells. DR antigen density could be increased by more than twofold over 48 hours upon exposure to gamma-interferon (gamma-IFN), whereas colony-stimulating factors had no effect. This was associated with a dose-dependent inhibition of total CFU-GM number, and a relative, but not absolute, increase in the ratio of monocyte colonies to granulocyte colonies. Similarly, in day 7 suspension cultures of purified myeloid precursor cells, gamma-IFN inhibited cell proliferation and increased the ratio of monocytes to granulocytes. Thus, despite the induction of high levels of HLA-DR antigen on precursor cells (a marker of monocyte commitment), the dominant in vitro effect of gamma-IFN was inhibition of granulocyte differentiation.

Antibodies, Monoclonal↗
PubMed1984

Stroke after carotid endarterectomy: risk as predicted by preoperative computerized tomography.

In patients undergoing carotid endarterectomy, the role of preoperative computerized tomographic head scanning in predicting the risk of postoperative neurologic deficit was determined by a retrospective evaluation of a select group of 107 consecutive patients with preoperative scans. Patients with infarction determined preoperatively by computerized tomography were found to be at a significantly higher risk for postoperative neurologic deficit than patients with a normal preoperative computerized tomographic scan. History and physical examination alone detected only 66 percent of the infarctions found with preoperative computerized tomographic scanning in these patients. Because the incidence of infarction revealed computerized tomography in patients with symptoms of a reversible ischemic neurologic deficit was 22 percent, we have proposed a new definition of reversible ischemic neurologic deficit to include the necessary finding of a normal computerized tomographic scan. Patients who presented with transient ischemic attack and the unexpected finding of a subclinical infarction on the preoperative scan were at the same significantly higher risk for postoperative stroke and a permanent neurologic deficit. Computerized tomographic scanning of potential carotid endarterectomy patients is of benefit not only to rule out other sources of neurologic symptoms, but also to predict more accurately the risk of postoperative neurologic deficit.

Adult↗