Controlling duration of contact between T cells and antigen-presenting cells.

A new method which allows precise control of the duration of contact between T cells and antigen-presenting cells (APCs) has been developed. A glass coverslip coated with poly-L-lysine, and then with T cells, was placed at the base of a cylindrical well, and the well was filled with liquid medium. A round coverslip, on which APCs were adhered, was supported on the surface of the medium by surface tension, cell-side down.

Controlled cell deformation produces defined areas of contact between cells and ligand-coated surfaces.

A method which allows precise control of the time of initiation and the area of contact of T cells with immobilized ligands has been developed. Cells are trapped in an asymmetric film that can be quantitatively thinned by reducing the film's capillary pressure. Ligands adsorbed to the base of the apparatus are forced into close contact with the cells as the air-liquid interface is drawn down.

Model of structural and functional adaptation of small conductance vessels to arterial hypotension.

Vascular networks adapt structurally in response to local pressure and flow and functionally in response to the changing needs of tissue. Whereas most research has either focused on adaptation of the macrocirculation, which primarily transports blood, or the microcirculation, which primarily controls flow, the present work addresses adaptation of the small conductance vessels in between, which both conduct blood and resist flow. A simple hemodynamic model is introduced consisting of three parts: 1) bifurcating arterial and venous trees, 2) an empirical description of the microvasculature, and 3) a target shear stress depending on pressure.

Gene structure of the human receptor tyrosine kinase RON and mutation analysis in lung cancer samples.

The human RON gene (MST1R) maps to 3p21.3, a region frequently altered in lung cancer and other malignancies. It encodes a receptor tyrosine kinase (RTK) closely related to MET, whose mutations are associated with neoplasia.

Dependence of T cell activation on area of contact and density of a ligand-coated surface.

An apparatus which allows precise control of the time of initiation and the area of contact of cells with immobilized ligands has been developed. Cells are trapped in an asymmetric film that can be quantitatively thinned, forcing the cells into close contact with ligands adsorbed on the base of the apparatus. Using microbeads to indicate the film height, the amount of thinning can be controlled to within 1 microm, producing known contact areas between cells and the ligand-coated surface.

Psychosocial and neuropsychological function in children with epilepsy.

This paper reviews the psychosocial and neuropsychological effects of epilepsy on children and families across environments in which children function, specifically home and school. Epilepsy is a chronic disorder, affecting one percent of the population, that alters neurocognitive functioning effecting learning, memory and family adaptation. A review of epilepsy and its impact on quality of life, family and school function and psychiatric comorbidity are discussed.

Integrin-mediated RON growth factor receptor phosphorylation requires tyrosine kinase activity of both the receptor and c-Src.

Cooperation between integrins and growth factor receptors plays an important role in the regulation of cell growth, differentiation, and survival. The function of growth factor receptor tyrosine kinases (RTKs) can be regulated by cell adhesion to extracellular matrix (ECM) even in the absence of ligand. We investigated the pathway involved in integrin-mediated RTK activation, using RON, the receptor for macrophage-stimulating protein.

Evaluation of 11C-colchicine for PET imaging of multiple drug resistance.

Unlabelled: Overexpression of P-glycoprotein (P-gp) can confer multiple drug resistance (MDR) phenotype on cancer cells and tumors by reducing intracellular accumulation of various cytotoxic agents. Early diagnosis of MDR in the clinic will serve to improve the efficacy of chemotherapeutic intervention and the quality of life of patients. In this article we describe use of a positron-emitting MDR tracer, 11C-colchicine (CHC), to evaluate MDR by PET imaging.

Two independent signaling pathways mediate the antiapoptotic action of macrophage-stimulating protein on epithelial cells.

In addition to its effects on macrophage function, macrophage-stimulating protein (MSP) is a growth and motility factor for epithelial cells. The growth and survival of epithelial cells generally require two signals, one generated by interaction with extracellular matrix via integrins, the other initiated by a growth factor. Therefore we investigated the effect of MSP on epithelial cell survival.

Interaction of macrophage-stimulating protein with its receptor. Residues critical for beta chain binding and evidence for independent alpha chain binding.

Macrophage-stimulating protein (MSP) and hepatocyte growth factor/scatter factor (HGF/SF) are plasminogen-related growth and motility factors that interact with cell-surface protein tyrosine kinase receptors. Each one is a heterodimeric protein comprising a disulfide-linked alpha chain and a serine protease-like beta chain. Despite structural similarities between MSP and HGF, the primary receptor binding site is located on the alpha chain of HGF/SF but on the beta chain of MSP.

Radiologic assessment of temporal lobe epilepsy.

Neuroimaging plays an important and increasing role in assessing patients with epilepsy. This article focuses on procedures used to evaluate patients who have failed medical treatment for epilepsy but may benefit from resective surgery. Radiologic assessment and use of the intracarotid amobarbital procedure are described.

Macrophage stimulating protein-induced epithelial cell adhesion is mediated by a PI3-K-dependent, but FAK-independent mechanism.

Macrophage stimulating protein (MSP) is a growth and motility factor that mediates its activity via the RON/STK receptor tyrosine kinase. MSP promotes integrin-dependent epithelial cell migration, which suggests that MSP may regulate integrin receptor functions. Integrins are cell surface receptors for extracellular matrix.

Capture of rare cells in suspension with antibody-coated polystyrene beads.

A method for the separation of one cell type present in small number from a predominant mixture of cell types using macroscopic polystyrene beads is demonstrated. An antibody specific to murine leukocytes (CD45) was adsorbed to the surface of the beads. Beads and murine hybridoma B cells were placed in test tubes and periodically inverted at fixed time intervals, causing the beads to settle through the suspension under creeping flow conditions.

Kinases involved in MSP/RON signaling.

Macrophage stimulating protein (MSP) belongs to the plasminogen-related kringle domain family. In addition to stimulation of macrophages, MSP acts on other cell types including epithelial and hematopoietic cells. The MSP receptor is a transmembrane tyrosine kinase called RON in humans and STK in mice.

Characterization of free alpha- and beta-chains of recombinant macrophage-stimulating protein.

Human serum macrophage-stimulating protein (MSP) induces motile activity of murine resident peritoneal macrophages and is a growth and motility factor for epithelial cells. It belongs to the plasminogen-related family of kringle proteins, and is secreted as a single-chain, 78-kDa, biologically inactive pro-MSP. Proteolytic cleavage of pro-MSP at a single site yields active MSP, a disulfide-linked alphabeta-chain heterodimer.

No evidence for radiation-induced clastogenic factors after in vitro or in vivo exposure of human blood.

Experiments were performed with human plasma irradiated in vitro or in vivo in order to evaluate the extent to which clastogenic factors might disturb the adaptive response to DNA-damaging factors currently studied in our laboratory. The studies were carried out with plasma isolated from whole blood given 4 Gy of X-rays in vitro and with plasma from people receiving local radiotherapy at a total dose of about 60 Gy gamma rays. Addition of irradiated plasma to culture medium did not result in a statistically significant increase in structural aberrations in chromosomes of non-irradiated normal blood.

Effectiveness of physicians-in-training counseling for smoking cessation in African Americans.

This study examined the effectiveness of smoking cessation counseling by physicians-in-training (residents) with African-American patients. One hundred fifty-eight family and internal medicine residents at a large urban public general hospital participated in the study; two thirds of the residents underwent a 2-hour smoking cessation training program. Ninety-two of the trained physicians counseled from 1 to 18 patients.

Proteolytic cleavage and activation of pro-macrophage-stimulating protein and upregulation of its receptor in tissue injury.

Macrophage stimulating protein (MSP) exists in blood as inactive pro-MSP. Cleavage yields active MSP, the ligand for a membrane receptor (RON) that is expressed on keratinocytes as well as macrophages. Because both cells have roles in tissue injury, we looked for active MSP and expressed RON in wounds.

Consistent, persistent expression from modified retroviral vectors in murine hematopoietic stem cells.

Retroviral vectors based on the Moloney murine leukemia virus (MoMuLV) have shown inconsistent levels and duration of expression as well as a propensity for the acquisition of de novo methylation in vivo. MoMuLV-based vectors are known to contain sequences that are capable of suppressing or preventing expression from the long terminal repeat. Previously, we constructed a series of modified retroviral vectors and showed that they function significantly better than MoMuLV-based vectors in vitro.

Mode of receptor binding and activation by plasminogen-related growth factors.

Hepatocyte growth factor/scatter factor (HGF/SF) and macrophage stimulating protein (MSP) are plasminogen-related kringle proteins that lost serine protease domain enzymatic activity and became ligands for cell surface tyrosine kinase receptors. They are activated by cleavage to disulfide-linked alphabeta chains. Surprisingly, despite structural similarities, the high affinity receptor binding regions of the two proteins are different: alpha chain for HGF, and beta chain for MSP.

Effects of secondary flow caused by a curved channel on plasma protein adsorption to artificial surfaces.

The effects of secondary flow induced by a curved channel on fibrinogen deposition and replacement on a glass surface were studied. Platelet adhesion to surface-bound fibrinogen was also studied to indicate how secondary flow may affect thrombogenesis on artificial surfaces. A saline pre-wetted channel with straight and curved sections was exposed to flowing plasma at a Reynolds number of 28.

Controlling receptor-ligand contact to examine kinetics of T cell activation.

A method for controlling the contact of cell-surface receptors with immobilized ligands has been developed. Cells are trapped in an asymmetric liquid film that can be quantitatively thinned by reducing the film's capillary pressure. Ligands adsorbed to the liquid-solid interface are forced into increasingly tighter contact with the cells as the air-liquid interface is drawn down.

Infection of human marrow stroma by human immunodeficiency virus-1 (HIV-1) is both required and sufficient for HIV-1-induced hematopoietic suppression in vitro: demonstration by gene modification of primary human stroma.

Patients with human immunodeficiency virus-1 (HIV-1) infection often present with bone marrow (BM) failure that may affect all hematopoietic lineages. It is presently unclear whether this failure reflects a direct viral impairment of the CD34+ hematopoietic progenitor cells or whether the virus affects the BM microenvironment. To study the effects of HIV-1 on the BM microenvironment, we examined the stromal cell monolayers in long-term BM culture (LTBMC), which are the in vitro equivalent of the hematopoietic microenvironment.