Rate of tension development in isometric contractions of a human hand muscle.
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Adult↗
Biomedical subjects
R G Miller
Publications and source records attributed to R G Miller.
Usage of the flow cytometer-cell sorter.
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Animals↗
Hoechst 33342 dye uptake as a probe of membrane permeability changes in mammalian cells.
Flow cytometric analysis of the uptake of the DNA-specific and fluorescent probe Hoechst 33342 (HO342) offers a simple and rapid method for measuring membrane transport rates in mammalian cells and identifying cellular subpopulations that differ in their membrane transport rates. In a Chinese hamster ovary wild-type cell line and in three colchicine-resistant lines derived from it, the rate of uptake of HO342 dye decreases as the stepwise resistance to colchicine increases. A colchicine-sensitive revertant cell line shows an increased rate of dye uptake. Drug resistance in these lines has previously been shown to be related to changes in transport rate. In a manner similar to colchicine, the rate of uptake of HO342 dye shows nonsaturation kinetics. The effects of KCN, a metabolic inhibitor, on HO342 dye uptake, both in the presence and in the absence of glucose, is similar to that previously observed for colchicine uptake. When murine spleen cells are stained with HO342 under appropriate conditions, one sees two populations of lymphocytes differing in HO342 fluorescence intensity, a difference not related to DNA content. The two subpopulations show the same relative difference in both colchicine and HO342 uptake. HO342 dye appears, therefore, to enter mammalian cells by the same mechanism as colchicine--i.e., by unmediated diffusion--and can be used as a probe of cytoplasmic membrane permeability. Potential applications of the dye in studies of drug resistance, detection of activated T cells, and recognition of lymphocyte subpopulations are discussed.
Animals↗
Diuresis in the ascitic patient: a randomized controlled trial of three regimens.
To compare the efficacy of three commonly used diuretic regimens in the treatment of ascites, we randomized 90 patients to three treatment groups: Sequential Spironolactone (spironolactone followed by furosemide if necessary), Combination (spironolactone and furosemide in combination), and Furosemide (furosemide given alone). Diuretics were begun at a low dose by mouth and the dosage increased until a 0.4-0.8 kg daily diuresis was achieved. The clinical and laboratory findings were comparable for the three experimental groups on admission to the study. All three regimens achieved a comparable rate of diuresis. To do so was far more difficult with furosemide alone, which required repetitious upward adjustments in dosage and massive KCl supplements. The incidence of encephalopathy, hepatorenal syndrome, and marked electrolyte abnormalities was similar for the three treatment groups except that severe hyperkalemia was more frequent on combination therapy. We conclude that diuresis should be initiated with one of the two spironolactone regimens and not with furosemide as the sole agent.
Ascites↗
Rat C-6 glioma cells maintained in an organ culture system: a study of kinetic parameters.
Rat C-6 glioma cells were grown on a sponge foam matrix in an organ culture system and the cell cycle parameters, including the growth fraction (GF), were assessed after autoradiography. The zones of growth consisted of a compact upper layer (UL) at the gaseous interface, a central necrotic layer and a deeper lower layer (LL) which invaded the matrix. The fraction of continuously labeled mitoses (FCLM) was similar in both the UL and LL cells. The derivatives of the FCLM curves obtained in three experiments gave an average modal TG2 of 5 hr. A mathematical model relating GF, TG2, TC and labeling index as a function of time, LI(t), was devised for cells in a steady state exposed continuously to tritiated thymidine and was applied to data obtained from UL cells. A mean GF of 9% (range: 8-10%) and a mean cell cycle time (TC') of 27 hr (range: 13-47 hr) were obtained. The mean TS was calculated to be 11 hr (range: 8-16 hr) by the method of grain counts per mitotic figure or grain index (GI). Knowledge of TS permitted alternative calculation of the cell cycle time from the equation Ts/TC = LI(0)/GF:this gave a mean cell cycle time (TC") of 29 hr (range: 20-45hr). Except for the GF, the cell kinetics were comparable to those of the same cell line grown in monolayer culture. The GF in the in vitro system described is in the lower range reported in some human malignant gliomas in vivo.
Animals↗
Differentiation of T cells from immature precursors in murine T cell colonies.
We describe a system for growing murine colonies containing subsets of functional T cells derived from immature T cell precursors. In contrast with previously described systems in which colony formation appears to depend upon activation and clonal expansion of mature T cells, we obtain comparable or increased numbers of colonies after depletion of T cells from spleen or bone marrow, or on culturing spleen or bone marrow from athymic nude mice. The proportion of cells expressing the T cell surface markers Thy-1, Lyt-1, and Lyt-2 is highly variable from colony to colony, consistent with the colonies arising from immature T cells, which differentiate in the colonies to give rise to various subsets of mature T cells.
Animals↗
Stimulation of human NK cell activity by cultured cells. II Ingestion of aspirin by blood donors suppresses induced NK activity.
Incubation of mononuclear cells with a melanoma tumour cell. M4, induces a rapid increase in NK cell activity in both normal and tumour patient cells. A marked individual variation among the patient population can be attributed to the prior ingestion of aspirin. Single therapeutic doses of aspirin (two tablets, 660 mg) taken 12 hr prior to donation of the blood sample cause an 80-100% reduction in the NK cell activity induced by M4. Since many patients coming to cancer clinics take aspirin regularly, it is essential that they be questioned about their recent usage of this drug if their cells are to be used in assays for NK activity.
Antibody-Dependent Cell Cytotoxicity↗
Opposite polarity of filipin-induced deformations in the membrane of condensing vacuoles and zymogen granules.
Filipin binding to membrane sterols induces deformations of the membrane that are detected by freeze-fracture either as 20- to 25-nanometer protuberances or as pits on the fracture faces. By using the filipin probe in pancreatic acinar cells, it was found that the polarity of filipin-induced deformations in the membrane limiting the Golgi condensing vacuoles is opposite that in the membrane limiting the mature zymogen granules. This asymmetry could be due to unequal partitioning of cholesterol between the membrane leaflets in these two compartments during the transformation of the condensing vacuole into the zymogen granule.
Cholesterol↗
An immunological suppressor cell inactivating cytotoxic T-lymphocyte precursor cells recognizing it.
The immune system does not normally react against self components. Originally, it was postulated that self-reactive cells were somehow deleted or blocked. More recent thinking is that such cells are suppressed by regulatory networks similar to those limiting the immune response against non-self determinants. Both mechanisms may exist. I describe here a type of suppression more closely related to the first postulate. In the in vitro, one-way, mixed lymphocyte reaction (MLR), cytotoxic T-lymphocyte precursor cells (CLP) from the responder population give rise to cytotoxic T-lymphocytes (CL) capable of lysing target cells from the stimulator population. A subpopulation of cells in the spleen of athymic nude mice can, when added to such cultures, inactivate CLP capable of recognizing either the H-2 antigens or TNP modifications of the nude spleen. Regarding the nude spleen cells, activation of self-reactive cells is being prevented.
Animals↗
Do 'lipidic particles' represent intermembrane attachment sites?
Although freeze-fracture electron microscopy is normally analysed with the presumption that particles represent proteins embedded within the membrane, particles which appeared to represent inverted lipid micelles within membranes have been reported. I have now confirmed the occurrence of particles in protein-free liposomes, but have found that they behave like intermembrane attachment sites rather than structures within a membrane.
Calcium↗
Discrimination between self and nonself.
An hypothesis is presented that relates the ability of the immune system to distinguish between "self" and "nonself", the generation of diverse lymphocyte receptors and the role of the major histocompatibility complex. Experimental evidence supporting this hypothesis includes the recent discovery of a cell in the thymus that appears to inactivate thymus-derived lymphocytes reactive against self histocompatibility antigens.
Animals↗
Cells in bone marrow and in T cell colonies grown from bone marrow can suppress generation of cytotoxic T lymphocytes directed against their self antigens.
Both normal mouse bone marrow and cells from T cell-containing colonies grown in vitro from normal bone marrow contain cells which can specifically suppress the development of cytotoxic T lymphocytes capable of recognizing alloantigens on the bone marrow or colony cells. Suppression, as assessed by reduction in cytotoxic activity, is produced by adding bone marrow or colony cells to mixed lymphocyte reactions between lymph node responder cells and irradiated histoincompatible spleen stimulator cells. The cytotoxic activity is reduced if the added bone marrow or colony cells are syngeneic or semisyngeneic to the stimulator cells but not if they are allogeneic. Suppression results from a reduction in the number of cytotoxic lymphocyte precursor cells activated in the cultures. The suppressor cells in bone marrow are radiation sensitive and Thy-1 negative; those in colonies grown from bone marrow are radiation resistant and Thy-1 positive.
Animals↗
Quantitative studies on the precursors of cytotoxic lymphocytes. VI. Second signal requirements of specifically activated precursors isolated 12 h after stimulation.
It is shown that, in a mixed lymphocyte reaction, the production of cytotoxic T lymphocytes (CL) from cytotoxic T lymphocyte precursors (CLP) requires two signals which are separated time. Using a flow cytometer-cell sorter and a vital, fluorescent DNA stain, Hoechst 3342, CLP specific for the stimulator cells can be separated from other CLP and from stimulator cells 12 h after initiation of mixed lymphocyte cultures. These CLP are in a state of partial activation and can produce CL in the absence of stimulator cells if a second signal in the form of a concanavalin A-induced spleen cell supernate factor is added. Specific CL are also generated when the partially activated CLP are cultured with both nude spleen cells and stimulator cells. In this case it appears that an interaction between the stimulator cells and the nude spleen cells leads to production of the second signal.
Animals↗
Abetalipoproteinemia. Report of two cases and review of therapy.
The clinical presentation and course of abetalipoproteinemia in two male patients, a child and an adult, are described. Apoprotein B was absent in both cases and each patient had > 50% acanthocytes present on peripheral blood smear. Family studies revealed normal lipid profiles in the parents of both patients, which is consistent with the usual autosomal recessive inheritance of this disorder. In addition to a low-fat diet, both patients have been maintained on high doses of vitamins A and E. In the adult patient, detailed evaluations over a five-year period have failed to show any progression of neurological disease while maintained on high-dose vitamins. The role of supplemental vitamins A and E in the therapy of abetalipoprotenemia is discussed.
Abetalipoproteinemia↗
The cubital tunnel syndrome: treatment with simple decompression.
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Adult↗
Cerebellar dyssynergia in humans--a quantitative analysis.
Patients with cerebellar lesions and limb ataxia performed two types of continuous tracking tasks involving flexion and extension of the index finger. In both tasks, patients were provided cutaneous and proprioceptive cues, but visual feedback was given in the first task (visual tracking) and not in the second (arbitrarily termed proprioceptive tracking). Raw records and Fourier-analyzed power spectra were compared with results in normal controls. Harmonic distortion was determined for each task. In all patients, as well as normal subjects, tracking performance was markedly improved and harmonic distortion substantially reduced during proprioceptive tracking. This surprising finding may result from a much shorter feedback loop for proprioceptive stimuli compared to visual stimuli. The tracking records, power spectra analysis, and determination of harmonic distortion provide both qualitative and quantitative data in patients with dyssynergia.
Cerebellar Ataxia↗
A design for a real-time fluorescence polarization computer.
We have developed hardware components for our flow cytometer cell sorter which can perform real-time calculations of either fluorescence polarization (FP) or anisotropy on a cell-by-cell basis and which can provide gating signals for the sorting of these cells into two populations. Artificial FP measurements, using electronic pulses varied over a 40dB range, were used to evaluate the computer's useful dynamic range. Real FP measurements, using human peripheral blood lymphocytes stimulated with phytohemagglutinin and labeled with fluorescein diacetate in saline, are presented to allow comparison with earlier work.
Computers↗
The neuropathy of abetalipoproteinemia.
The clinical, electrophysiologic, and pathologic features of the peripheral neuropathy in abetalipoproteinemia (Bassen-Kornzweig disease) have been described incompletely. On the basis of findings in threee patients, we believe that large muscle fibers in peripheral nerves are selectively affected and that weakness may be due to chronic partial denervation.
Abetalipoproteinemia↗