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Biomedical subjects

R G Miller

Publications and source records attributed to R G Miller.

At least 271 records · Page 15Linked to original sources
PubMed1984

Functional status of cells from lymphoid and myeloid tissues in mice with severe combined immunodeficiency disease.

Cells from mice with severe combined immunodeficiency disease (SCID) were tested in assays that measure myeloid and lymphoid function. Results showed that C.B-17 scid and their normal counterparts (C.B-17) have similar levels of spleen colony-forming units. The frequency of in vitro myeloid colony-forming units in C.B-17 scid spleen is elevated, but the absolute number of colony-forming units in C.B-17 scid and C.B-17 spleen is similar. The absolute number of bone marrow colony-forming units in C.B-17 scid and C.B-17 mice is comparable. Cells from C.B-17 scid spleen are consistently negative in all tests of B and T cell function. C.B-17 scid splenocytes fail to proliferate in response to T and B cell mitogens or to allogeneic lymphocytes in a one-way MLR; C.B-17 scid cells do serve as stimulators in MLR. B lymphocyte colony-forming units are absent, as are cytotoxic lymphocyte precursors and cells that can generate T cell colonies with cytotoxic progenitors. The microenvironment of the C.B-17 scid mouse is conducive to lymphocyte differentiation, because functional B and T cells are easily detectable in mice reconstituted with normal bone marrow cells. The results of this study indicate that scid specifically impairs the differentiation of stem cells into mature lymphocytes; myeloid cell differentiation is not affected.

Animals↗
PubMed1983

Differentiation from precursors in athymic nude mouse bone marrow of unusual spontaneously cytolytic cells showing anti-self-H-2 specificity and bearing T cell markers.

We describe an in vitro limiting dilution culture system that supports growth and differentiation of nylon wool nonadherent bone marrow cells from athymic nude mice. Cells were seeded at low cell numbers (5-120 cells per 20-microliter microculture well) in the absence of added filler or feeder cells but in the presence of conditioned medium. Microwells positive for growth appeared to contain a single clone of cells that adhered together to form a tight cluster referred to here as a colony. A fraction of colonies contained cells that expressed an unusual spontaneous cytolytic activity. They lysed syngeneic or semisyngeneic Con A blast or tumor cell targets but seldom lysed H-2-incompatible Con A blast or tumor target cells, even in a lectin-facilitated assay. A large fraction of colonies contained lymphoid cells that expressed the T cell markers Thy-1 and Lyt-1. Colonies expressing spontaneous cytolytic activity and also containing cells with Thy-1+ and/or Lyt-1+ markers could be grown from nylon wool nonadherent nude marrow cells depleted rigorously by cell sorting of cells expressing either of these markers. Expression of Thy-1 and spontaneous cytolytic activity in a particular colony was significantly correlated. Short-term lines established from cytolytic colonies with T cell markers maintained both characteristics. The cytolytic effector cells observed in these cultures may represent an early stage in the development of the T cell repertoire.

Animals↗
PubMed1983

Cells in murine fetal liver and in lymphoid colonies grown from fetal liver can suppress generation of cytotoxic T lymphocytes directed against their self antigens.

Fetal liver (FL) cells or, in much smaller numbers, cells in lymphoid colonies grown from FL of mouse strain A can suppress the development of cytotoxic activity in a B anti-A mixed lymphocyte reaction (MLR) but not a B anti-C MLR. A, B, and C represent three H-2 different mouse strains. Suppressor cells with similar properties have been described in thymus, bone marrow, lymphoid colonies grown from bone marrow, and athymic nude spleen. They have been referred to collectively as "veto cells". From the point of view of the suppressor cells, a response against self is being suppressed. The FL colony suppressor cells differ from those described in that they can sometimes also suppress an A anti-B response. The FL colony suppressor cells are Thy-1- and resistant to 1500 rad irradiation. These cells may play a role in maintenance of self tolerance. That they are found in FL as early as 13 days of gestation implies that potentially self-reactive cells may develop before experiencing the thymus environment.

Animals↗
PubMed1983

Generation of autoreactive cytotoxic T lymphocytes under limiting dilution conditions.

The ability of F1 (H-2k/d) responder cells to generate cytotoxic effector cells against parental and F1 targets was investigated under limiting dilution conditions. One hit limiting dilution curves, consistent with the generated cytolytic cells being the progeny of a single precursor cell, were reproducibly obtained if a culture was scored as "responding" on the basis of its ability to lyse one or more of a panel of Con A blast targets consisting of self F1 and both parents. The calculated frequency of the precursor cell in a nylon wool-nonadherent splenic responder cell population ranged from about 1/500 to 1/1600 in (B10.BR X B10.D2)F1 and (RNC X BALB/c)F1 mice. The patterns of lysis expressed by individual microcultures against the panel of F1 and both parental targets were unusual; besides patterns that were consistent with predictions of classic transplantation rules (i.e., lysis of F1 targets plus one/both parental targets), "anomalous" patterns (i.e., lysis of F1 targets or one/both parental targets exclusively) were also seen. The precursor cells that gave rise to cytolytic cells were devoid of T cell markers, whereas the cytolytic effector cells were Thy-1+, Lyt-2+, as defined by sensitivity to treatment with monoclonal antibody plus complement. The data are discussed in the context of early in vitro development of cytolytic T lymphocytes, with particular emphasis on a possible manifestation of an early T cell repertoire.

Animals↗
PubMed1983

Evidence for activated peripheral blood T-cells in rheumatoid arthritis.

We have previously demonstrated defective antigen specific T-suppressor (Ts) cell function in the peripheral blood lymphocytes (PBL) from patients with rheumatoid arthritis (RA). Our study was designed to delineate whether diminished Ts activity is due to impaired interleukin (IL) dependent clonal expansion of Ts cells or to prior in vivo activation. Patients with recent onset of RA, or a disease flare, exhibited enhanced IL generation (IL-1 and /or IL-2). Increased proportions of active E-rosettes, elevated spontaneous production of IgM, and total immunoglobulin in mitogen free cultures were consistent with the concept of prior lymphocyte activation in vivo. Our results do not support defective clonal expansion of Ts cells as the basis of deficient IL generation, but do support the concept of in vivo activation of PBM cells in some patients with RA.

Adult↗
PubMed1983

The extent of self-MHC restriction of cytotoxic T cells in nude mice varies from mouse to mouse.

There are conflicting results as to whether the response of athymic nude mice to TNP-modified self determinants is or is not H-2 restricted. We cultured spleen cells from 29 individual RNC (H-2k) nude mice with TNP-modified self determinants and tested the cultures for their ability to lyse TNP-modified self (RNC-TNP) and TNP-modified allogeneic (BALB/c-TNP) target cells. Each mouse was stimulated by two different protocols: either by the addition of TNP-modified irradiated nu/+ spleen cells or by TNP modification of the nude responder cells without addition of other cells. All mice could lyse RNC-TNP targets and about one-half could also lyse BALB/c-TNP targets, i.e., there was a 50:50 division between restricted and unrestricted responses. The magnitude of the response against RNC-TNP and whether the response was restricted were both independent of the method of stimulation. We conclude that H-2 restriction in these mice is imposed by an as yet unidentified environmental influence that can vary from one nude mouse to the next. The influence appears to act through negative selection because the modified self response is, if anything, higher in mice showing an unrestricted response.

Animals↗
PubMed1983

Growth at limiting dilution of human T cell colonies from T cell-depleted peripheral blood leukocytes.

Using a new culture system, we found that up to one-fourth of nylon-wool nonadherent human peripheral blood lymphocytes (NAd) could give rise to a colony containing T cells. Even after NAd cells were depleted of T cells (rosette-forming and/or OKT3+ cells and/or OKT11+ cells), up to one-ninth of cells could still give rise to a colony containing T cells. Colonies were grown in microwell liquid cultures in a vol of 0.02 ml/culture seeded with from 2 to 40 cells. Each cell concentration was set up with 60 or more replicates, and the results were analyzed using limiting dilution theory. Growth had an absolute requirement both for lymphokine(s) present in the supernatant of PHA-stimulated peripheral blood leukocytes and for PHA. A fit to limiting dilution theory could be obtained only when heavily irradiated (3000 rad) peripheral blood leukocytes or NAd cells were also included, 300 cells/well being optimum. The system supported the development of OKT3+ and OKT11+ cells from OKT3-, OKT11-, OKM1-, and OKla1- precursors. All colonies contained some OKT3+ and OKT11+ cells, usually more than half the colony cells carrying the markers. Some colonies also contained OKTM1+ cells and OKla1+ cells at a frequency such that some colony cells must carry more than one marker.

Adult↗
PubMed1983

What price Kaplan-Meier?

The asymptotic efficiency of the Kaplan-Meier product-limit estimator, relative to the maximum likelihood estimator of a parametric survival function, is examined under a random-censoring model.

Clinical Trials as Topic↗
PubMed1982

Flexible sorting decision and droplet charging control electronic circuitry for flow cytometer-cell sorters.

We describe sorting decision and droplet charging control electronic circuitry for a flow cytometer-cell sorter. The circuitry can handle up to five independent input signals and can sort in up to four directions. A sixth input channel is used to determine the presence or absence of an event requiring analysis. Sorting decisions are stored in a read-only memory semiconductor device. All the input signals for a given event are reexpressed as either 0 or 1 and are used to define an address in this memory which contains the desired sorting outcome for the event. A set of switches enables one to choose between many different procedures for relating input cell pulses to sorting outcomes by switching to different blocks of the memory. The circuitry has been found capable of purity of cell separation to the level permitted by "deadtime" in the preceding analog stages. It is in regular use with the Ontario Cancer Institute flow cytometer-cell sorter.

Cell Separation↗
PubMed1982

Time course of improved neuromuscular function following plasma exchange alone and plasma exchange with prednisone/azathioprine in myasthenia gravis.

Ten patients with myasthenia gravis (MG) were treated with weekly plasma exchange (PE) in combination with prednisone and azathioprine; 4 of the patients were treated with 3-6 PE alone, before instituting prednisone/azathioprine. Four clinico-physiological parameters of neuromuscular function as well as the anti-acetylcholine receptor antibody (anti-AChRAb) titers were measured 1-3 times per week. Evidence of improved neuromuscular function (NMF) was based on: (1) reduced % decrement of the maximum muscle compound potential following 2/s supramaximal nerve stimulation; (2) increased maximum force; (3) increased outstretched arm time, and (4) increased vital capacity. An early improvement in NMF occurred within the first 2 weeks (sometimes as early as 1-2 days), which was quantitatively comparable in patients treated with PE alone and PE plus prednisone/azathioprine. This early improvement reached a plateau, and was subsequently maintained for 3-4 weeks, followed by a later substantial improvement after 8-12 weeks of combined PE plus prednisone/azathioprine.

Adult↗
PubMed1982

Reliability of the thermodilution method in the determination of cardiac output in clinical practice.

The thermodilution (TD) method of determining cardiac output (CO) is widely used in clinical practice, but its reliability in this setting is not well understood and may be poor. This is especially true when dealing with unstable patients and using commercial TD devices. Numerous published reports have shown markedly variable results when comparing simultaneously the TD method and the Fick or dye-dilution methods in catheterization laboratories, intensive care units, or operating rooms. In order to assist clinicians in interpreting the reliability of the TD method in measuring CO, we analyzed all available published data (14 reports). The differing results in these reports were evaluated by standard statistical methods and by an extension of the influence function method of structural analysis developed to differentiate reproducibility and accuracy errors of each technique. Comparing the accuracy of the TD method with that of the Fick or the dye-dilution methods reveals that the 3 methods are of equal merit and can be used as independent references. Our reproducibility data show that when using commercial TD devices there must be a minimal difference of 12 to 15% (average, 13%) between determinations of cardiac output (3 measurements per determination) to suggest clinical significance. Minimal differences of 20 to 26% (average, 22%) are required between determinations when using 1 measurement per determination. There was no difference in the quality of the TD method when comparing rapid injection of iced or room temperature thermal indicator.

Cardiac Output↗
PubMed1982

Development of cytotoxic T lymphocyte precursor cells in T cell colonies grown in vitro.

T cell colonies grown in vitro from normal mouse spleen cells contain cytotoxic T lymphocyte precursor cells (CLP) that develop from immature precursors within the colonies. The colony-forming unit for CLP development (CFU-TCLP) has two components. One is Thy-1-, Lyt-1-, Lyt-2- and is found in spleen, nude spleen, and bone marrow. It can by itself produce a colony, but these colonies do not contain CLP. The other component is Thy-1+, Lyt-1-, Lyt-2- and is found in spleen and lymph node. The Thy-1+ component gives rise to the CLP that develop in the colony. A single cell in this component can give rise to multiple progeny CLP. Each colony develops CLP of several different specificities. The full repertoire developed includes specificities specific for allogeneic H-2, TNP-modified-self H-2 and TNP-modified-allogeneic H-2. Although CLP specific for TNP-modified-allogeneic stimulator cells are definitely present, there is a distinct preference for TNP-modified self. The results lead to the tentative conclusion that the T cell repertoire can develop in the absence of the special environment provided by the thymus.

Animals↗
PubMed1981

Generation of cytotoxic T-lymphocyte precursor cells in T-cell colonies grown in vitro.

The role of the thymus in T-lymphocyte differentiation remains unclear. The demonstration that the thymus can restrict the T-lymphocyte specificity repertoire suggests that T cells acquire specificity within the thymus. However, the demonstrations of immunocompetent helper T cells and cytotoxic T-lymphocyte precursor cells (CLPs) in athymic nude mice suggest that the acquisition of some T-cell reactivity may occur without the thymus. We have been using T-cell colonies grown in vitro as a model system for studying various aspects of T-cell differentiation in both mouse and man. In one study we showed that CLPs can be found in T-cell colonies grown from spleen cells of normal mice, each colony containing CLPs of several different specificities. The colonies containing CLPs are not clonal, appearing to have a colony-forming unit (CFU-T) of two (perhaps three) cells. Here we provide direct evidence that the CLPs are spontaneously produced in the colonies. In addition, the cells of the CFU-T were characterized with antisera directed against the cell-surface marker Thy-1, which is present on all murine T cells, and the cell-surface markers Lyt-1 and Lyt-2, which are differentially distributed on different T-cell subclasses. We found that the CFU-T contains both a Thy-1+ and a Thy-1- cell, neither of which seems to carry either Lyt-1 or Lyt-2 surface markers.

Animals↗