Search PubMed⌕ Search

Biomedical subjects

R G Miller

Publications and source records attributed to R G Miller.

At least 343 records · Page 19Linked to original sources
PubMed1977

Crystalline patterns of myelin lipids visualized by freeze fracture.

Freeze fracture of rat optic nerve reveals smooth, particle-free regions on the lammellar fracture faces of myelin when prepared by standard procedures. When the fixed, glycerin-impregnated tissue is incubated at 6 degrees C for two or more days, crystalline patterns indicative of a phase transition can be seen in the particle-free regions. The crystalline patterns can be destroyed by subsequent incubation at 37 degrees C and are not seen when the initial incubation is at room temperature or 37 degrees C. Butylated hydroxytoluene has no effect on the formation of the crystalline patterns. The time course of the formation of the crystalline patterns suggest that the rate-limiting step in the process is not the phase transition itself. We propose that the lipids associated with the particles in vivo are involved in the formation of the crystalline patterns.

Animals↗
PubMed1977

Early and late volume changes during erythroid differentiation of cultured Friend leukemic cells.

Friend erythroleukemic cells (FLC) can be induced to differentiate in vitro by addition of dimethylsulfoxide (DMSO). We have studied the kinetics of induction by measuring cell volume, volume coefficient of variation and cell doubling time. Two distinct volume changes (early and late) are observed after the addition of the inducing agent. The early change occurs after ten hours and consist of a 10-20% decrease in volume compared to an untreated control population. This shift persists for two days and its magnitude is proportional to both the concentration of DMSO and the number of differentiated cells seen on day 5. FLC lines which induce weakly or not all with DMSO exhibit a reduced or absent early volume shift. Inclusion of a local anaesthetic in the culture prevents the appearance of differentiated cells and also counteracts the early volume shift. The exact time of the early volume change is a function of cell growth rate and appears to be cell cycle related. Synchronized cell populations exposed to DMSO during G2 and S phase undergo one round of mitosis before expression of the volume change whereas cells in G2-M express the change only after a second mitosis. A later, more gradual decrease in volume is observed in those cultures which begin to produce hemoglobin. It occurs after approximately five doubling times and coincides with the first appearance of hemoglobin-containing cells. Volume distribution parameters indicate that only a proportion of the population becomes smaller in size.

Animals↗
PubMed1977

The systemic production of cytotoxic lymphoid cells in corneal allograft reaction. 1. A quantitantitative study utilizing 51chromium release assay.

The purpose of the study was to determine whether the mechanism of corneal allograft rejection is systemic in nature. Utilizing a 51Cr release assay in which labelled donor and recipient corneal cells were used as targets, it was demonstrated that cytotoxic cells specific for antigens located in donor corneal cells were present in spleen and lymph nodes.

Animals↗
PubMed1977

Measurement of cytoplasmic fluorescence depolarization of single cells in a flow system.

We have built a flow system in which we can analyze and sort individual viable cells on the basis of their cytoplasmic microviscosity. The average cytoplasmic microviscosity (or cytoplasmic structuredness) of a cell can be quantitated by exciting fluorescein molecules in the cytoplasm of the cell with a polarized light source and measuring the extent of depolarization of the fluorescent signal. Changes in the state of a cell (e.g., the reception of a signal inducing the cell to differentiate) often appear to be associated with changes in cytoplasmic microviscosity, these changes being detectable within hours of the inducing signal. An example of one such change is presented.

Bone Marrow↗
PubMed1977

Quantitative studies on the precursors of cytotoxic lymphocytes. I. Characterization of a clonal assay and determination of the size of clones derived from single precursors.

A microculture system for estimating the frequency of cytotoxic lymphocyte precursors (CLP) to alloantigens is described. Cytotoxic T lymphocytes (CL) were generated by culturing limiting numbers of RNC (H-2k)-nu/+lymph node (LN) cells with irradiated C3D2F1 (H-2k/d) spleen cells in the presence of RNC-nu/nu spleen cells for 7 days in microtiter trays. At the end of the culture period, individual wells were assayed for cytotoxic effector cells directed against 51CrP815 (H-2d) target cells. The effector cells generated under these conditions are sensitive to killing by rabbit anti-mouse brain serum and guinea pig complement. The process of differentiation from precursors to CL is radiation sensitive (Do approximately 180 rads). The frequency of precursors for H-2d was calculated by fitting the proportion of nonresponding cultures to the zero order term of the Poisson distribution, Po = e-vn, where Po = per cent nonresponders, v = precursor frequency, and N = number of LN cells cultured per well. The frequency of precursors in the RNC-nu/+LN population responding to the H-2d haplotype was found to be 1 in 776. Under conditions where no backstimulation is possible, the frequency of precursors responding to the H-2d haplotype is 1 in 885 for B6-nu/+LN and 1 in 2550 for B6-nu/+ spleen, respectively. In combination with a visual assay for individual CL, it was found that the average clone size per precursor after 7 days in culture is about 1040. Our assay could detect clones with as few as 40 CL/well. Since the average clone size in 26 times the detection limit, we conclude that the assay for CLP is highly sensitive and does not represent a minimum estimate.

Animals↗
PubMed1977

Requirement for non T-cells in the generation of cytotoxic T lymphocytes (CTL) in vitro. II. Characterization of the active cells in the spleen of nude mice.

Small numbers of LN cells will produce many more cytotoxic lymphocytes on in vitro culture with allogeneic stimulator cells if spleen cells from nu/nu mice are also present throughout the culture period. All cytotoxic cells produced are T cells and arise from precursors in the LN component. The nude spleen component appears to be providing a required non-T cell which has been lost from the LN component through dilution. At least two active subpopulations of cells, differing in sedimentation velocity, adherence properties, radiation sensitivity, and antigen recognition properties can be identified in the nu/nu spleen. The first, the dominant activity in normal nu/nu spleen, is nonadherent, radiation sensitive, and can synergize with either syngeneic or allogeneic LN cells provided both are different from the same alloantigens in the stimulator population. The second, found in nu/nu spleen cells precultured with alloantigen, sediments more rapidly, is adherent, and radiation resistant, and need not be allogeneic to the stimulator cells to synergize with LN cells. The first subpopulation may give rise to the second.

Animals↗
PubMed1977

Quantitative studies on the precursors of cytotoxic lymphocytes. II. Specificity of precursors responsive to alloantigens and to concanavalin A.

A microculture system was used to examine the specificity of cytotoxic T lymphocytes (CL) derived from single precursors. Our data indicate that clones derived from single precursors of CL (CLP) are specific. Thus, RNC mice (H-2k) simultaneously stimulated by both H-2d and H-2b antigens produce clones which are specific for either H-2b or H-2d but not for both. In lymph node (LN), the frequency of CLP giving rise to clones specific for H-2d and H-2b is 1/480 and 1/860, respectively. Clonal specificity is also maintained when Con A is used to activate the precursors. With a nonspecific assay of CL, it was found that 2.5% of the cells in LN are stimulated by Con A to produce clones of CL. Among the CLP stimulated by Con A, 2.1% of the clones are specific for H-2d alloantigens. An unexpected finding was that 18% of the clones produced by Con A stimulation lysed EL4 tumor cells, which carry H-2b; however, only a small proportion of these clones were specific for the H-2b alloantigen. The antigen on EL4 which accounts for the high response has not been characterized.

Animals↗
PubMed1976

Requirement for non-T cells in the generation of cytotoxic T lymphocytes in vitro. I. Use of nude mice as source of non-T cells.

The ability of small numbers of LN cells to produce cytotoxic lymphocytes on in vitro culture with allogeneic stimulator cells is greatly augmented by the addition of spleen cells from athymic nude mice. The possibility that the synergism is a result of improved culture conditions or a "feeder effect" is excluded. All cytotoxic cells found in these cultures are shown to be T cells and to arise from precursors contained in the LN-cell component. The nude spleen cell component appears to be providing a required non-T cell which has been lost from the LN component through dilution. Synergism between the two components can occur whether they are syngeneic or allogeneic provided that both can recognize the same alloantigens in the stimulator population.

Animals↗
PubMed1976

The estimation of the number of binding sites for antibody on antigen molecules with reference to factor VIII and its antibody.

The theoretical basis for determining the number of antibody sites on antigen molecules is examined. The theoretical considerations are applied to factor VIII molecules. Examples based on data available at the Oxford Haemophilia Centre are calculated to illustrate the approach. It is concluded that there are few sites on each factor VIII molecule for human antibody. The three antibodies for which reasonable data were available suggest 1-3 sites for human antibody. The data for rabbit antibody suggest 5-6 sites per factor VIII molecule.

Absorption↗
PubMed1976

Von Hippel-Lindau's disease.

A patient with Von Hippel-Lindau's disease was followed from the time of diagnosis to the time of his death 13 year later. He was asymptomatic when the diagnosis was made, although a hemangioblastoma of the medulla was found on angiography. The patient's course and autopsy are described and the features of this disease are reviewed.

Adenocarcinoma↗
PubMed1976

Stem cell characterization of neutropenia: velocity sedimentation and mass culture analysis.

Human bone marrow obtained from patients with neutropenia contains a cell population which is absent or diminished in normal marrow. The abnormal population is composed of cells of volume 200-300 mum3 which sediment at 5-5 to 8-5 mm/h. Normal marrow contains one cell class giving rise to increased numbers of grnaulocyte colonies after mass culture, while marrow obtained from neutropenic patients, or from patients with marrow regeneration, shows two such populations; one of these cell classes corresponds to the abnormally large cells demonstrated on velocity sedimentation analysis. This population of large cells may represent a group of either self-renewing cells related to the committed granulocyte progenitors or the pluripotent stem cell.

Adult↗
PubMed1976

Hereditary sensory neuropathy and tonic pupils.

The clinical features of two siblings with both hereditary sensory neuropathy and bilateral tonic pupils are described. Other neurologic disorders associated with tonic pupils are reviewed. Our patients appear to represent a unique instance of the association of disorders that primarily affect the ciliary and dorsal root ganglia.

Adult↗
PubMed1976

Characterization of cells that suppress the cytotoxic activity of T lymphocytes. I. Quantitative measurement of inhibitor cells.

Target cell lysis by sensitized cytolytic T lymphocytes (CTL) may be conveniently quantitated by 51Cr release. By fitting to the formula, P (% specfic release) = 100 (1-e-Nat) one obtains alpha, the relative frequency of CTL in N lymphoid cells. Using a microassay and murine sarcoma target cells, we observed an unexpected decrease in lysis whenever effectors obtained from a graft-vs-host reaction were tested at high concentrations. This inhibition was not observed with CTL generated by an MLC reaction. Inhibition could not be explained by nonspecific mechanical 'crowding', reutilization of released isotope, suppression of release from dead target cells, or the particular strain combination and target used. By modifying the formula to allow suppression of CTL by a stochastic cell-cell interaction with suppessor cell, we found that P = 100 (1-e-Nate-Ngamma) adequately fitted the data, where Ngamma is proportional to inhibitor content. An 18- to 24-hr incubation at 37 degrees C but not 4 degrees C allowed selective depletion or enrichment of inhibitors; in mixing experiments, both parameters Nalpha t and Ngamma behaved stoichiometrically as independent cellular properties. The inhibitor was resistant to concentrations of anti-T cell (RAMG) serum + complement which killed -TL. A similar inhibitor arose in vivo during an anti-tumour allograft response. The ability to quantitate CTL and inhibitor activities from titration curves provides a technique for studying the identity and mechanism of suppressor cells acting at the effector stage of cell-mediated immunity.

Animals↗
PubMed1976

Reduction of the in vitro cytotoxic lymphocyte response produced by in vivo exposure to semiallogeneic cells: recruitment or active suppression?

Twenty-four hours after intravenous injection of (C57BL/6 X DBA/2)F1 hygrid lymphoid cells into C57BL/6 mice, the in vitro cytotoxic lymphocyte (CL) response of the C57BL/6 spleen and LN cells against DBA/2 alloantigens can be greatly reduced. The reduction is specific for the foreign alloantigens injected; is reduced by irradiating the cells before injection; develops significantly within 10 min of injection, thereafter increasing with a time constant of about 2 hr; varies with the number and origin of cells injected; can be induced byseveral subpopulations of injected cells within one tissue; varies with the host organ tested (e.g., injection of 10(4) semiallogeneic LN cells can reduce hose LN response more than 100-fold and have no effect on host spleen); and (for the LN response) is largely reversed by treatment with anti-H-2 antibody plus complement specific for the injected cells. The reduction appears to be induced by grafted cells entering host lymphoid organs rather than, e.g., host cells being specifically recruited to go elsewhere. When cocultured with normal cells, lymphoid cells from mice injected as above do not reduce the in vitro CL response of the normal cells but do if left in vivo for 7 days before testing. If left 1 day in vivo, followed by 4 days culture in vitro with the same alloantigen, they strongly reduce the normal cell response. The reduction is increased by both the in vivo and in vitro exposure. The grafted cells, once in the host lymphoid tissue, appear to activate a host suppressor mechanism which develops in vitro and reduces the CL response.

Animals↗