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At least 109 records · Page 6Linked to original sources
PubMed1969

Properties of a cell fraction that repairs damage to the cell division mechanism of Escherichia coli.

A factor in bacterial cell extracts which induces cell division in filaments of Escherichia coli produced by irradiation was found to be associated with a heat-labile particulate fraction which sediments at about 100S. Frozen or lyophilized samples of the cell extracts were stable for considerable periods of time. Fractions purified by centrifugation contained 2% of the total protein of the extract but no measurable ribonucleic acid or deoxyribonucleic acid. The extracts were inactivated by incubation with phospholipase A, lipases, and detergents, but not by incubation with selected nucleases and proteases.

Bacterial Proteins↗
PubMed1983

Morphometric analysis of thyrotropes in developing and cycling female rats: studies of intact pituitaries and cell fractions separated by centrifugal elutriation.

The development and morphology of immunocytochemically stained thyrotropes were studied in sections of intact pituitaries and dissociated cell fractions separated by centrifugal elutriation. In the initial cell suspension from six elutriation experiments, adult female rat thyrotropes were 4.8 +/- 0.5% (+/- SE) of the cell population. Correlative morphometric studies of Araldite- or glycol methacrylate-embedded pituitaries showed that there were no changes in the percentage of thyrotropes with the stage of the estrous cycle and that the percentage of thyrotropes (5.14 +/- 0.4%) was not significantly different from the percentages in the initial cell suspension. TSH cell area fraction (a) measurements (with a 10,000-microns 2 ocular grid) showed that adult rat thyrotropes covered 171 +/- 5 microns 2 of the grid area and averaged 15 microns in diameter. In neonatal rats, thyrotropes were half the a of those in the adult for the first 9 days of life. Thereafter, they expanded, and the a reached adult levels by 20-21 days of development. TSH cell percentages remained 2-3 times adult levels throughout postnatal development (2-22 days). This developmental pattern contrasted with that in the male, which showed adult percentages of thyrotropes by 15 days of age. In the elutriation experiments from adult rats, thyrotropes were 2- to 4-fold more concentrated in the fractions eluted at 37.0 ml/min or greater, which contained the largest cells. Fraction 7 (39.5 ml/min) showed a 2-fold enrichment of thyrotropes to 11.6 +/- 1.4%, and fraction 8 showed a 4-fold enrichment to 19.6 +/- 2.7%. A few small TSH cells were found in the fractions 1-3, eluted at 11.8-19.5 ml/min. Electron microscopic studies showed that some of these small TSH cells were poorly granulated and difficult to distinguish from small gonadotropes, whereas the large thyrotropes resembled those described previously in the adult or developing male rat. These studies, thus, combine techniques of immunocytochemistry, morphometrics, and cell separation by elutriation to describe TSH cells in the female rat pituitary. Our findings agree with those reported by Denef et al., who showed that thyrotropes in the adult male rat are among the largest cells in the pituitary. The few small thyrotropes in the female rat may be equivalent to the prolific cells described by Leuschen et al. in the male rat that enrich monolayers from these fractions after 7 days in culture.

Age Factors↗
PubMed1986

Increasing antigenicity of B16 melanoma cell fraction with microwave hyperthermia.

An injection of a fraction of a fraction (C30 mw) obtained by centrifugation at 30 kg of homogenate of B16 melanoma cells, treated with microwave hyperthermia (2450 MHz, CW, 44 degrees C, for 20 minutes), increases the survival time (p less than 0.01) of C57-BL/6J male mice inoculated 26 days later with 10(7) cells (viability greater than 95%) of B16 melanoma. This delay of 26 days between these two injections corresponds to the moment where the synthesis of immunoglobulins is increased in protected mice. The earliest death (p less than 0.001) of animals injected with untreated tumoral cell fraction (C30), and that received a suspension of viable B16 melanoma cells (10(7)) can be explained by an inhibition of humoral immunity system.

Animals↗
PubMed1984

Localization of factor VIIIC: antigen in guinea-pig tissues and isolated liver cell fractions.

Factor VIIIC:antigen (VIII:CAg) was estimated in guinea-pig tissues by an immunoradiometric assay using a human inhibitor antibody. In homogenized guinea-pig tissues, VIII:CAg was shown to be stable and to be predominantly located in the liver (9 +/- 1.2 units; mean +/- SEM, n = 8). Lesser amounts were detected in spleen (1.3 +/- 0.02 units), lung (0.6 +/- 0.07) and kidney (0.4 +/- 0.06). In isolated liver cell fractions separated by centrifugal elutriation VIII:CAg was mainly detected in the hepatocyte fraction (0.3 +/- 0.07 units/10(8) cells;mean +/- SEM, n = 5) and in lesser amounts in the endothelial (0.02 +/- 0.01 units/10(8) cells) and the Kupffer cell fractions (0.05 +/- 0.02 units/10(8) cells). The liver concentration of VIII:CAg was (0.17 +/- 0.02 units/g) which was 20% of the plasma concentration (0.96 +/- 0.01 units/ml, n = 8) suggesting that VIII:CAg may not be stored in the liver but is rapidly exported following synthesis.

Animals↗
PubMed1983

Cell fractionation with affinity ligands conjugated to agarose-polyacrolein microsphere beads.

A new effective insoluble support useful for cell fractionation based on agarose-polyacrolein microsphere beads (APAMB) of diameters 150--250 micrometers has been developed. The synthesized polyacrolein (PA) microspheres, of average diameter 0.2 micrometer, are provided with reactive aldehyde groups through which various ligands containing primary amino groups are bound covalently in a single step at physiological pH. Antibodies coupled to the microspheres are very effective for labelling of cell surface receptors on human red blood cells and mouse lymphoid cells. APAMB were obtained by encapsulating the PA microspheres with agarose. Antibodies and lectins bound to the APAMB serve to construct affinity columns for the separation of red blood cells and murine lymphocyte subpopulations. Anti-human red blood cell antibodies coupled to anti-immunoglobulin APAMB are effective in separating human from turkey red blood cells, whereas either anti-Thy 1.2 anti-immunoglobulin antibodies or soybean agglutinin coupled to APAMB have proved useful for the separation of T and B cells from heterogeneous population of spleen cells. The separation procedure is simple, rapid and effective. The viability of the fractionated cells is unaffected by the procedure and the recovery of the cells is high: between 80% and 100%.

Acrolein↗
PubMed1973

The role of thymocytes and bone marrow cells in defining the response to the dinitrophenyl hapten attached to positively and negatively charged synthetic polypeptide carriers. Cell fractionation over charged columns.

An inverse relationship exists between the net electrical charge of immunogens and the antibodies they elicit (1). Results of an earlier study have demonstrated that the net charge phenomenon has a cellular basis, since the immune response potential of murine spleen cells to 2,4-dinitrophenyl (DNP) on a negatively charged synthetic polypeptide carrier was reduced by cell fractionation over negatively charged glass beads, whereas the response to the same hapten on a positively charged carrier was unaffected (14). To verify that the net charge correlation is expressed at the cellular level, spleen cells were fractionated over positively charged poly-L-lysine-coated glass bead columns, and their immunocompetence to DNP on positively and negatively charged carriers was tested by cell transfers in irradiated recipient mice. In this case, the fractionated cells showed reduced response potential to DNP on the positively charged carrier only. Thus, the cellular basis of the net charge phenomenon has been demonstrated for both positively and negatively charged immunogens (for the same specificity) by cell separation techniques over columns of opposite charge. In order to establish whether the cell population relevant for the charge properties of immunogens was of thymus or marrow origin, thymocytes and bone marrow cells were selectively passed over positively or negatively charged columns and mixed with unfractionated cells of the complementary type. Transfers of the filtered and unfiltered cell mixtures in irradiated recipient mice immunized with DNP on either a positive or a negative synthetic polypeptide carrier indicated that fractionation of thymocytes, but not of marrow cells, correlated with the spleen population. Thus, thymocytes fractionated over negatively charged columns and mixed with unfractionated marrow cells exhibited reduced response to DNP on the negative carrier, but normal responses to DNP on the positive carrier. The opposite result was obtained when thymocytes were passed over positively charged columns. No effect on the anti-DNP response was detected by filtration of bone marrow cells over columns of either charge. These findings indicate that it is possible to distinguish between thymocytes on the basis of their capacity to react with more acidic or more basic surfaces and that a population of thymus-derived cells may recognize immunogens on the basis of their overall electrical charge. No evidence was found by these techniques that marrow-derived cells contribute to the net charge phenomenon.

Animals↗
PubMed1977

[Immunodepressive activity of cell fractions of Escherichia coli O138:K81:H19].

A soluble cell fraction (cytosol), an O-antigen (endotoxin), and an unsoluble cell ingredient were isolated from a 24-hour culture of Escherichia coli O138:K81:H19. Their immunosuppressive action was determined by using the tuberculin test and the survival rate of the allographts. It was found that: 1. Cytosol appears to be a slightly toxic preparation with well expressed immunosuppressive action. 2. The endotoxin is highly toxic, producing the same effect as cytosol. 3. The unsoluble cell ingredient is a comparatively toxic preparation, producing an undependable immunosuppressive effect. Discussed is the mechanism of the immunosuppressive activity of the investigated subcellular fractions. It believed to be due to a certain injurious action on the function of the T-cells.

Animals↗
PubMed1975

Bicarbonate ion-ATPase in rat liver cell fractions.

The distribution of HCO3MINUS-ATPase activity was studied in cell fractions prepared from homogenates of rat liver. The level of mitochondrial contamination in the microsomal fraction depended on the fractionation procedure and on the method of homogenization. With proper care, microsomes with undetectable mitochondrial contamination could be prepared. These microsomes had no detectable HCO3MINUS-ATPase activity. Approximately 85% of the total HCO3minus-ATPase activity of the post 6000 times g-min supernatant was recovered in the mitochondrial fraction. The properties of this mitochondrial HCO3minus-ATPase were not distinguishable from those of the various microsomal HCO3minus-ATPases previously described by other investigators.

Adenosine Triphosphatases↗
PubMed1990

Simultaneous multielement determination in vegetable foodstuffs and their respective cell fractions by total-reflection X-ray fluorescence (TXRF).

Total-reflection X-ray fluorescence (TXRF) was employed in the multielement determination made on samples of lamb's lettuce and cauliflower as well as in the analysis of their soluble and insoluble cell fractions. All samples were digested with HNO3 and the elements were quantitatively determined with Ga as internal standard. For cell fractionation, the freeze-dried vegetables were mortared in the presence of fine-grain quartz and extracted with a buffer solution; the resulting suspension was then separated by ultracentrifugation into cytosol and pellet components. K, Ca, Mn, Fe, Cu, Zn, Rb and Sr were the elements of which the total content and distribution between cytosol and pellet were determined. As a result of the cellular digestion and extraction procedures employed, greater than or equal to 50% of the total metal contents of Zn, Cu, K and Rb could be reduced to the cytosol phase in both vegetables, however, Sr, Fe, Ca and Mn were mainly bound to the insoluble pellet components which, in the case of cauliflower, contained up to 100% of the total Sr content. As a multielement method, TXRF proved to be an excellent analytical tool in these investigations, since it requires only minute samples with simple preparation and involves a large dynamic measuring scale.

Calcium↗
PubMed1976

Mechanisms of leucocyte migration inhibition by breast tumour cell fractions.

Leucocyte migration inhibition by autologous breast tumour cell fractions was mediated by a soluble factor synthesized and released by mononuclear leucocytes and active against migrating granulocytes. This mechanism is similar to that previously described in respect to cell-mediated sensitivity to microbial antigens. Alternative mechanisms involving directly reactive granulocytes or cytophilic antibodies were rarely operative in the migration tests.

Antibodies, Neoplasm↗
PubMed1981

Intracellular localization of 2',3'-cyclic nucleotide 3'-phosphodiesterase in a neuronal cell line as examined by immunofluorescence and cell fractionation.

The enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase, EC 3.1.4.37) occurs not only in myelin fractions and glial cells, but can also be shown to be present in a CNS cell line of neuronal origin (B104). Direct immunofluorescence microscopy of B104 cells with fluorescein isothiocyanate-conjugated rabbit anti-CNPase antibodies shows a discrete and specific intracytoplasmic location of CNPase. Fractionation of the cells was performed by differential centrifugation of a cell homogenate and continuous sucrose density-gradient centrifugation. As monitored by marker enzyme activities, CNPase seems to be associated with endoplasmic reticulum membranes.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1975

Separation of mouse spleen haematopoietic cell fractions for transplantation purposes in lethally irradiated mice.

Mouse cells were fractioned by adherence chromatography on glass beads. The fractionation of spleen cells yielded 5 different fractions, whose transplantation effect was tested by the method of Till and McCulloch. The results of these transplantation tests showed that the chosen form of adherence chromatography was not sufficiently successful, since none of the resultant fractions contained solely colony-forming units (CFU) and in none of them were CFU present in an exeptionally high concentration.

Animals↗
PubMed1985

Cell-cycle differences of HL-60 leukemia cells fractionated by centrifugal elutriation.

HL-60 leukemia cells were fractionated into G1 and S/G2 populations using a rapid centrifugal elutriation technique, and studied for differences between the cell-cycle phases. The G1 fraction was found to contain smaller cells with a sedimentation velocity of 7 mm/h. The S/G2 fraction consisted of larger cells with a sedimentation velocity of 125 mm/h. The latter fraction was found to have a peak level of the enzyme (2'-5')An-binding protein, as compared to the G1 fraction, indicating a possible role for (2'-5')An-binding protein and its products in the growth regulation of these leukemic cells. In addition, cytofluorometric analysis of fractionated HL-60 cells indicates that elutriation is an effective fractionation method, rapidly yielding large numbers of cells for study, without the use of chemical treatments.

Carrier Proteins↗
PubMed1979

[Studies of the presence of enzymes in various tissues of swine. 4. Studies of the Ca-, Mg-, and Na-K-ATPase activities in the homogenate and cell fractions of brain of fetuses and piglets].

Studies were conducted into the activities of calcium, magnesium, and sodium-potassium ATPase as well as into crude protein levels in homogenate and cell fractions of brain of two foetuses, aged 111 days, and of two piglets each, aged two days or nine weeks. The average brain-borne crude protein percentages were 6.55 in the foetuses, 7.25 in the two-day piglets, and 9.60 in the nine-week piglets. Calcium, magnesium, and sodium-potassium ATPase activities, related to one gram of fresh brain mass, were found to go up along with growing age. Highest relative percentages of sodium-potassium ATPase were recordable from homogenate and from the mitochondrial and microsomal fractions of the foetuses. Certain quantitative differences were obtained from using calcium, magnesium, sodium, and potassium ions to stimulate ATPase in the fractions of cell nuclei, mitochondria, and microsomes. The optimum temperature for magnesium and sodium-potassium ATPase in homogenate and in the mitochondrial fraction of brain was 45 degrees C.

Adenosine Triphosphatases↗
PubMed1988

Glutamate synthase in Medicago sativa L. Occurrence and properties of FD-dependent enzyme in plant cell fraction during root nodule development.

In the plant cell fraction of Medicago sativa (L. cv Europe) nodules, glutamate synthase is active with reduced Fd, MV, NADH and NADPH as an electron donor. Up to 25 to 30 days after inoculation, the activities of Fd-dependent glutamate synthase (EC 1.4.1.7), the most active form of the enzyme, NADH-dependent (EC 1.4.1.14) and NADPH-dependent (EC 1.4.1.13) glutamate synthases increase about 2-fold followed by a relatively constant level per gram fresh weight of nodules. The activities of glutamate synthases with different electron carriers increase constantly about 30-fold after 46 days of inoculation by total fresh weight of nodules per plant. These nodule glutamate synthase activities with Fd, NADH or NADPH represent 30% relative to those of root glutamate synthases per plant with the respective electron donor. Fd-glutamate synthase in nodule plant fraction is a protein molecule immunochemically distinct from pyridine nucleotide-glutamate synthases. MV-linked enzyme activity is associated with Fd-glutamate synthase. The Fd-glutamate synthase has a subunit molecular mass of 68.2 kDa, and it exhibits a high affinity for spinach Fd as an electron carrier. The increase in Fd-glutamate synthase activity during nodule development is accompanied by a rise in the enzyme protein content. The total activity of different forms of glutamate synthase in vitro ensures a higher level than the rate of ammonia production during N2 fixation in bacteroids of Medicago sativa nodules.

Blotting, Western↗
PubMed1967

Adenosine phosphate hydrolases in cell fractions of Vitreoscilla.

Bound, soluble, and whole-cell fractions of two strains of the gliding bacterium Vitreoscilla were found to contain two enzymes capable of hydrolyzing adenosine phosphates: a Mg(++)-activated adenosine triphosphatase with a temperature optimum of 37 C, and a Mg(++)-activated adenosine diphosphatase with a temperature optimum of 55 C. Both enzymes had an optimal pH response between 8.5 and 9.5. Maximal activation was achieved at an ionic strength of 0.2 for the adenosine triphosphatase and at 0.3 to 0.4 for the adenosine diphosphatase. Preliminary studies indicated a molecular weight of approximately 50,000 for the adenosine diphosphatase and a molecular weight greater than 60,000 for the adenosine triphosphatase. Comparisons are made with previously reported characteristics of these enzymes in other bacteria, and a hypothesis is offered as to the role these enzymes have in the gliding mechanism.

Adenosine Triphosphatases↗
PubMed1978

Hemopoietic stem cell transplantation using mouse bone marrow and spleen cells fractionated by lectins.

Mouse bone marrow and spleen cells were fractionated with the aid of soybean agglutinin and peanut agglutinin. A test for spleen colony-forming units in the isolated fractions showed that the hemopoietic stem cells are agglutinated by both of these lectins. The capacity of the agglutinated fractions to reconstitute lethally irradiated allogeneic mice was investigated. A sequential fractionation of splenocytes from SWR donors by soybean agglutinin and peanut agglutinin, or a single fractionation by soybean agglutinin of splenocytes from BALB/c donors, afforded a cell fraction that successfully reconstituted lethally irradiated (BALB/c X C57BL/6)F1 mice, without complications due to graft-versus-host reaction.

Animals↗