Showing papers by "Kettering University published in 1973"
TL;DR: The distinction between human B and T lymphocytes on the basis of their surface architecture can be made by SEM of critical point dried samples, with relative ease in most but not all instances.
Abstract: In this study a variety of human lymphocytes of known B or T cell type, obtained from multiple sources, were prepared for scanning electron microscopy (SEM) by the critical point drying method. Distinction between normal B and T lymphocytes was relatively easy in most instances, on the basis of their surface architecture. Using immunological methods, between 20 and 30% of normal peripheral blood lymphocytes (PBL) were identified as B cells and from 69 to 82% as T cells. SEM results showed that 20% of the PBL had a complex villous surface and approximately 80% of cells were smaller and had a relatively smooth surface. Comparison of the above data and enrichment of B cells from PBL, by centrifugation after T cell rosettes had formed, indicated that the "villous" cells were B lymphocytes and the "relatively smooth" cells were T lymphocytes. T cells obtained from two human thymuses were also of the generally smooth cell type. Further evidence for the distinction of B and T lymphocytes, on the basis of surface morphology, was obtained from the examination of cultured lymphoid cell lines of known B or T cell derivation. Cells from cases of chronic lymphocytic leukemia also provided support for the above interpretations. Five of six untreated cases were clearly of B cell type by immunologic and SEM criteria. One unusual case showed the presence of T and B lymphocytes in almost equal numbers by SEM and a mixture of B and T cells by immunologic markers. An additional case that had received chemotherapy showed numerous atypical cells that were difficult to classify by SEM. Detailed examination of the smoother T cells showed that at least half of them had a moderate number of surface digitations and a small proportion had an intermediate surface morphology with a relatively large number of surface digitations. The latter presented difficulties in classification and may correspond to different stages of differentiation and represent subpopulations of lymphocytes. The distinction between human B and T lymphocytes on the basis of their surface architecture can be made by SEM of critical point dried samples, with relative ease in most but not all instances. The effects of stimulation, cell cycle, differentiation, intercellular contact, and density of cell population, on the surface architecture of lymphoid cells, remain to be determined.
315 citations
170 citations
TL;DR: The oxidation-reduction properties of the g = 1.82 component and its flash-induced kinetic behavior in relation to that of P870 are those expected for the primary electron acceptor in bacterial photosynthesis.
110 citations
TL;DR: Detergent treatment releases from both avian and mammalian oncornaviruses a structure containing the viral RNA and a major arginine-rich protein, as well as reverse transcriptase activity.
Abstract: Detergent treatment releases from both avian and mammalian oncornaviruses a structure containing the viral RNA and a major arginine-rich protein, as well as reverse transcriptase activity.
96 citations
TL;DR: The oxidation-reduction reaction of each of the bound iron-sulfur species, as represented by the changes of the electron paramagnetic resonance spectra, was reversible and apparently involved a two-electron change.
Abstract: Digitonin - fractionated photosystem - I subchloroplasts were titrated potentiometrically between -450 and -610 mV at pH 10. Examination of the titrated subchloroplasts by low-temperature (13 degrees K) electron paramagnetic resonance spectroscopy revealed resonances centered at values of 2.05, 1.94, 1.92, 1.89, and 1.86 on the g-factor scale. The peak heights depended on the potentials at which the chloroplasts were poised. The resonances of at least three iron-sulfur centers can be recognized: one with lines at g = 2.05 and 1.94; one with lines at g = 2.05, 1.92, and 1.89; and one for which only a line at g = 1.86 has been resolved. The midpoint potentials of the iron-sulfur species fall into two distinctly separate regions: the titration profile of the g = 1.94 signal, the first segment of the g = 2.05 plot, and the rise phase of the g = 1.86 signal had a value of -530 +/- 5 mV; the upper segment of the g = 2.05 plot, the decrease phase of the g = 1.86 signal, and the g = 1.89 profile had a midpoint potential estimated to be [unk] -580 mV. The oxidation-reduction reaction of each of the bound iron-sulfur species, as represented by the changes of the electron paramagnetic resonance spectra, was reversible and apparently involved a two-electron change.Titration at pH 9 could only be carried to -560 mV, and essentially only the first half of the titration behavior as found at pH 10 was seen. At any given potential more positive than -560 mV, the part of the iron-sulfur protein that was not reduced electrochemically could be reduced photochemically, but only to the maximum extent reduced electrochemically at -560 mV. Whereas, chloroplasts illuminated at room temperature and then frozen while still being illuminated developed a signal similar to that produced by electrochemical reduction at -610 mV, illumination at 77 degrees K did not bring about photoreduction beyond that accomplished electrochemically at about -560 mV.Dithionite alone in the dark and under anaerobic conditions brought about a partial reduction to the extent of the first electrochemical reduction step. Dithionite plus illumination at room temperature or dithionite plus methyl viologen in the dark produced the maximum signal. Electron paramagnetic resonance spectra due to either light or electrochemically reduced iron-sulfur proteins showed no detectable decay for at least 3 days when samples were stored in the dark at 77 degrees K.
81 citations
TL;DR: The major subpopulation consisted of small lymphoid cells and comprised 80%–90% of all cells, was of high relative density and rich in θ, TL, G IX , Ly-A, Ly-B, and Ly-C, but contained little or no H-2 and could be reproduced by treating whole thymus with anti-TL or anti-θ sera.
75 citations
TL;DR: The Fv-l locus of the mouse, a major determinant of the biology of murine leukemia virus, is very closely linked to Gpd-1 on chromosome 4 (linkage group VIII).
Abstract: The Fv-l locus of the mouse, a major determinant of the biology of murine leukemia virus, is very closely linked to Gpd-1 on chromosome 4 (linkage group VIII).
66 citations
TL;DR: It is proposed that different spectral varieties of chlorophylls exist in the photosynthetic unit of green plants in order to accelerate the transfer of excitation energy to the reaction center, and thus allow the operation of physically larger units with greater light- Harvesting power.
65 citations
TL;DR: A model array set up to represent a photosynthetic unit of 344 chlorophyll molecules of seven different spectral varieties and in definite orientations constitutes a model for the control of energy distribution between the two photosystems, as indicated in recent years through fluorescence studies.
63 citations
Patent•
16 Apr 1973TL;DR: In this paper, a container for liquids having a substantially cylindrical stainless steel hollow body and a protective chime of rigid or semi-rigid resilient plastics material at at least one end of the body is described.
Abstract: A container for liquids having a substantially cylindrical stainless steel hollow body and a protective chime of rigid or semi-rigid resilient plastics material at at least one end of the body, characterised in that the body has a rib adjacent the said one end of the body, the chime extends over the rib and to lock the chime to the body a portion of the chime has been deformed behind the rib by a hot moulding process.
62 citations
TL;DR: The spectra indicate that the 4 bacteriochlorophyll a and 2 bacteriopheophytin a molecules in the reaction center are contained in a single pigment complex.
TL;DR: Flash photolysis studies in a number of labora tor ie~ have shown that 3Chl a in fluid solutions is efficiently quenched by quinones, probably via electron transfer to the quencher, and the triplet state of the chlorophyll is strongly implicated as the electron donor.
Abstract: The existence of triplet state chlorophylls in uitro has been well e~tablished,'-~ but the role of such intermediates in photosynthesis is ~ n c e r t a i n . ~ For example, it is thought that one of the functions of carotenoids in the chloroplast is to protect the system from damage by photooxidation.6 This effect is apparently due to oxidation by singlet oxygen ('A#), which is formed by energy transfer' from the lowest triplet state of chlorophyll a (Chl a) to molecular oxygen. Another possibility-perhaps one within the mainstream of biochemical events-is electron transfer from the triplet state of chlorophyll ( T h l ) to form a wcation radicaLs Oxidized forms of the respective chlorophylls are evidently involved in both green plant9 and bacterial'O photosynthesis, and there is evidence that in uitro photooxidation of Chl a can proceed via the triplet state. Flash photolysis studies in a number of labora tor ie~ ' .~~ ' ' '~ have shown that 3Chl a in fluid solutions is efficiently quenched by quinones, probably via electron transfer to the quencher. In frozen solutions, both quinones15 and aromatic nitrocompounds'6 can photooxidize Chl a, the efficiencies being proportional to the redox potentials of the oxidant. However, involvement of T h l a in these reactions can only be inferred, since the experiments were carried out under steady illumination. Seely\" employed a series of substituted nitrobenzenes as oxidants (Ox) and measured the rates of pyrochlorophylland Chl a-sensitized photoreduction of the nitro-compounds by hydrazobenzene in 7:3 (v/v) ethanol-pyridine at room temperature. He found a good correlation between the quantum yields and the polarographic quarter-wave reduction potentials of the nitro-compounds. Since fluorescence quenching is negligible under the conditions employed, the triplet state of the chlorophyll is strongly implicated as the electron donor. Thus, Seely's results show that the reaction:
TL;DR: Observations regarding some of these AKR sublines have been collected from several laboratories because such differences can be crucial to the usefulness of AKR mice for biomedical research.
Abstract: THE AKR inbred line of mice, developed as a strain with a high incidence of leukaemia, has found wide use in the fields of genetics, immunology, virology, and cancer research While a certain degree of variability is expected among sublines derived from any inbred strain, rather striking differences have been observed among AKR sublines Because such differences can be crucial to the usefulness of AKR mice for biomedical research, observations regarding some of these AKR sublines have been collected from several laboratories
TL;DR: Some experiments with human lymphocytes from blood and tonsils, the two sources of such cells most readily available are reported, which show the importance of knowing the kinetics and distribution of these cells.
Abstract: TWO types of lymphocyte cooperate in initiating the humoral response to antigen: the B cell is the progenitor of antibody-forming cells and the T cell acts in a helper capacity. The activity of a third cell, the macrophage, is also required. Although the functions of B and T cells are antigen-specific, that of the macrophage is not. Most knowledge about the kinetics and distribution of the two types of lymphocytes, their specificity, and their susceptibility to inhibition or stimulation, has been established by experiments with mice. Progress has been facilitated in particular by the development of methods that measure the response of mouse spleen cells to antigen in vitro; we report here some experiments with human lymphocytes from blood and tonsils, the two sources of such cells most readily available.
TL;DR: The findings suggest either that African and American Burkitt's lymphoma are different diseases, or that E.B. virus is unlikely to be the aetiological agent of Burkitt’s lymphoma in both Africa and America.
TL;DR: One of these cell-derived proteins, which is present in a variety of uninfected cell types, closely resembles actin and has the property of undergoing a time-dependent aggregation in the extracts.
Abstract: Several methods have been explored for the detection and characterization of viral proteins from soluble extracts of cells transformed by Rous sarcoma virus (RSV). Viral antigens have been analyzed after gel filtration in several solvents. In addition, immune complexes formed with virus-specific sera have been isolated by agarose gel filtration and by high- or low-speed centrifugation through sucrose solutions. Radioactive proteins from these immune complexes have been analyzed by gel filtration in 6 m guanidine hydrochloride or by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Comparison with proteins from purified virus indicates the presence of two viral core proteins (gs1 and gs2) in the soluble fraction from virus-producing chicken cells. In the same fraction from RSV-transformed hamster cells (which do not produce virus), three gs proteins (gs1, gs2, and gs3) could be identified. The soluble viral gs proteins are strongly bound to at least two larger polypeptides in cell extracts. These polypeptides do not appear to be viral in origin and have the property of undergoing a time-dependent aggregation in the extracts. One of these cell-derived proteins, which is present in a variety of uninfected cell types, closely resembles actin.
TL;DR: In an effort to rescue components of a hypothetical human sarcoma virus genome, a human rhabdomyosarcoma cell line was infected with the GA strain of FeLV or the rat-tropic Kirsten strain of murine sarcomA virus and virus productive cell lines were established.
Abstract: IN an effort to rescue components of a hypothetical human sarcoma virus genome1,2, a human rhabdomyosarcoma (RD) cell line3 was infected with the GA strain of FeLV4 or the rat-tropic Kirsten strain of murine sarcoma virus5 and virus productive cell lines were established. During these studies the RD-114 virus was accidentally discovered6,7 and it became of interest to compare the properties of the four cell lines (parent RD cells, RD-114 cells, RD-FeLV cells and RD-KiMSV cells) and the viruses released from three of the lines (RD-114 virus, RD-FeLV virus, RD-KiMSV virus).
TL;DR: While the direct cytotoxic test is less sensitive than the quantitative absorption methods, it should serve for detection of antigenic specificities unique to brain.
TL;DR: A new type of hemoprotein was isolated from extracts of Azotobacter vinelandii using a heat step, application of the protamine-cellulose phosphate procedure, and precipitation with MgCl2.
TL;DR: If the pre-illuminated subchloroplast particles were allowed to recover at room temperature by standing in the dark for 10 min or by addition of a chemical reductant, subsequent illumination of the sample at 77 °K yielded an EPR spectrum consisting of signals due to both P700+ and reduced iron-sulfur protein.
TL;DR: In this article, the effect of light intensity during growth on the electron-transport components and the photochemical activities of the chloroplasts of the white mustard plants was studied, and it was suggested that most of the P700 in low-light plants is involved in a cyclic electron flow which is coupled to phosphorylation.
TL;DR: It is thought that even if hybridization and autoradiographic efficiencies were 100%, then at most only 6 × 10−6 silver grains would have been produced over the diploid cell's haemoglobin loci.
Abstract: Price, Conover and Hirschhorn1 have reported the in situ hybridization of haemoglobin mRNA to diploid chromosomes. We think such a conclusion to be impossible because the specific activity of their mRNA was 6 × 10−7 disintegrations per mRNA molecule during the two week exposure of their autoradiographs. As a genome has been reported to contain less than five haemoglobin cistrons2, even if hybridization and autoradiographic efficiencies were 100%, then at most only 6 × 10−6 silver grains would have been produced over the diploid cell's haemoglobin loci.
TL;DR: A common antigen (S2), initially thought to be uniquely associated with human sarcomas, has been found to be widely distributed in patients with other tumors as well and Absorption studies with human embryonic tissues suggest that S2 may be a fetal antigen.
Abstract: A common antigen (S(2)), initially thought to be uniquely associated with human sarcomas, has been found to be widely distributed in patients with other tumors as well. Absorption studies with human embryonic tissues suggest that S(2) may be a fetal antigen. The presence of antibody to S(2) in patients with tumors and in their relatives implies a propensity in these individuals for cellular dedifferentiation which may be a prerequisite for malignant transformation.
TL;DR: This chapter discusses the phenomenon of biochemical interference, the role of sample quality on the analysis, and the effect of biological variation in the reported values.
Abstract: Publisher Summary This chapter discusses the phenomenon of biochemical interference, the role of sample quality on the analysis, and the effect of biological variation in the reported values. Serum or plasma, prepared with various anticoagulants, are used in clinical chemical analysis. The isoenzymes of 6-phosphogluconate dehydrogenase that are determined by electrophoresis on starch gel, but not on agarose, differ according to the anticoagulant used for collecting blood. Many constituents—such as magnesium, potassium, phosphorus, and enzymes—are present in the formed elements of blood, in concentrations many times higher than in the surrounding plasma. Thus, the lysis of cells can contaminate the plasma or serum to a measurable amount. The red cells can release material that interferes in the analytical procedure by contributing color to the reaction, as occurs in the biuret determination of protein, or direct interference in a chemical reaction, as in uric acid assays, which depend on phosphotungstate reduction.
TL;DR: When Semliki Forest virus (SFV)-infected BHK cells were disrupted 4 h after infection, 75 to 90% of the total virus-specific RNA synthesizing enzyme was found in the large particle fraction, along with 75 to ninety percent of the in vivo-synthesized double-stranded RNAs.
Abstract: When Semliki Forest virus (SFV)-infected BHK cells were disrupted 4 h after infection, 75 to 90% of the total virus-specific RNA synthesizing enzyme was found in the large particle fraction, along with 75 to 90% of the in vivo-synthesized double-stranded RNAs. The RNA products of this enzyme-template complex in an in vitro system were double-stranded RNAs sedimenting predominantly at 18S, and single-stranded RNAs sedimenting at 42S, 26S, and 22S. The various virus-specific SFV RNAs synthesized in vitro were associated with different sized structures, and thus each was separable by differential centrifugation. Kinetic and pulse-chase experiments showed that the double-stranded RNAs were the precursors to the single-stranded RNAs. There were several double-stranded RNAs identified both in the in vitro product and also in extracts from infected cells. The major replicative form had a molecular weight of 4.4 × 106.
TL;DR: It is proposed that selective methylation of nascent proteins, such as myosin, can begin at the level of polyribosomes and be completed in the cytosol of muscle cells cultured in vitro.
TL;DR: E. coli DNA polymerase I has been used to synthesize DNA complementary to rabbit globin mRNA, and in addition to the heteropolymeric DNA, poly ( dT) and poly (dA)·(dT) are also synthesized.
TL;DR: In this paper, the authors demonstrate that plant dictyosomes can be dissociated into component cisternae in media of high ionic strength, neutral pH, low temperature, and varying ion composition.
Abstract: In media of high ionic strength, neutral pH, low temperature, and varying ion composition, plant dictyosomes were disassembled into component cisternae. The effective ions included phosphotungstate and several halides. Constituents of the intercisternal or bonding regions were revealed through electron microscope analysis. These included intercisternal elements and electrontransparent plaques of undetermined composition. The intercisternal plaques were confined to the central platelike regions of cisternae and were distinct from the intercisternal fibers. The findings demonstrate that plant dictyosomes can be dissociated into component cisternae. With monovalent halide salts, the unstacking process was sufficiently mild to reveal constituents of the intercisternal region as well as yield intact single cisternae.
TL;DR: The data are most compatible with the idea of a regulatory function for the dihydrofolate reductase protein in this organism.
Abstract: Dihydrofolate reductase is markedly hyperproduced in strains of Diplococcus pneumoniae which bear any one of a unique group of sense to sense mutations (amer) in the corresponding structural gene. Increased enzyme levels mediated by the amer mutations are apparently the result of increased rates of de novo synthesis. The basis for these effects could be transcriptional, translational or could involve an increase in messenger RNA stability. Data revealing no difference in stability of the related mRNA in a variety of mutants and the wild-type strain appear to eliminate the last possibility. Other data support the idea of an effect on transcription. This includes the extreme sensitivity of amer mutation expression following genetic transformation, to inhibition by actinomycin D and rifampacin, and the presence in one extremely high level mutant (amer-3 with 120 times the wild-type enzyme content) of increased amounts of mRNA. The data are most compatible with the idea of a regulatory function for the dihydrofolate reductase protein in this organism.